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old malloc implementations
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malloc-2.6.4.c
/* Malloc implementation for multiple threads without lock contention.
Copyright (C) 1996-2001, 2002 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Wolfram Gloger <[email protected]>
and Doug Lea <[email protected]>, 1996.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/* $Id$
This work is mainly derived from malloc-2.6.4 by Doug Lea
<[email protected]>, which is available from:
ftp://g.oswego.edu/pub/misc/malloc.c
Most of the original comments are reproduced in the code below.
* Why use this malloc?
This is not the fastest, most space-conserving, most portable, or
most tunable malloc ever written. However it is among the fastest
while also being among the most space-conserving, portable and tunable.
Consistent balance across these factors results in a good general-purpose
allocator. For a high-level description, see
http://g.oswego.edu/dl/html/malloc.html
On many systems, the standard malloc implementation is by itself not
thread-safe, and therefore wrapped with a single global lock around
all malloc-related functions. In some applications, especially with
multiple available processors, this can lead to contention problems
and bad performance. This malloc version was designed with the goal
to avoid waiting for locks as much as possible. Statistics indicate
that this goal is achieved in many cases.
* Synopsis of public routines
(Much fuller descriptions are contained in the program documentation below.)
ptmalloc_init();
Initialize global configuration. When compiled for multiple threads,
this function must be called once before any other function in the
package. It is not required otherwise. It is called automatically
in the Linux/GNU C libray or when compiling with MALLOC_HOOKS.
malloc(size_t n);
Return a pointer to a newly allocated chunk of at least n bytes, or null
if no space is available.
free(Void_t* p);
Release the chunk of memory pointed to by p, or no effect if p is null.
realloc(Void_t* p, size_t n);
Return a pointer to a chunk of size n that contains the same data
as does chunk p up to the minimum of (n, p's size) bytes, or null
if no space is available. The returned pointer may or may not be
the same as p. If p is null, equivalent to malloc. Unless the
#define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
size argument of zero (re)allocates a minimum-sized chunk.
memalign(size_t alignment, size_t n);
Return a pointer to a newly allocated chunk of n bytes, aligned
in accord with the alignment argument, which must be a power of
two.
valloc(size_t n);
Equivalent to memalign(pagesize, n), where pagesize is the page
size of the system (or as near to this as can be figured out from
all the includes/defines below.)
pvalloc(size_t n);
Equivalent to valloc(minimum-page-that-holds(n)), that is,
round up n to nearest pagesize.
calloc(size_t unit, size_t quantity);
Returns a pointer to quantity * unit bytes, with all locations
set to zero.
cfree(Void_t* p);
Equivalent to free(p).
malloc_trim(size_t pad);
Release all but pad bytes of freed top-most memory back
to the system. Return 1 if successful, else 0.
malloc_usable_size(Void_t* p);
Report the number usable allocated bytes associated with allocated
chunk p. This may or may not report more bytes than were requested,
due to alignment and minimum size constraints.
malloc_stats();
Prints brief summary statistics on stderr.
mallinfo()
Returns (by copy) a struct containing various summary statistics.
mallopt(int parameter_number, int parameter_value)
Changes one of the tunable parameters described below. Returns
1 if successful in changing the parameter, else 0.
* Vital statistics:
Alignment: 8-byte
8 byte alignment is currently hardwired into the design. This
seems to suffice for all current machines and C compilers.
Assumed pointer representation: 4 or 8 bytes
Code for 8-byte pointers is untested by me but has worked
reliably by Wolfram Gloger, who contributed most of the
changes supporting this.
Assumed size_t representation: 4 or 8 bytes
Note that size_t is allowed to be 4 bytes even if pointers are 8.
Minimum overhead per allocated chunk: 4 or 8 bytes
Each malloced chunk has a hidden overhead of 4 bytes holding size
and status information.
Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
needed; 4 (8) for a trailing size field
and 8 (16) bytes for free list pointers. Thus, the minimum
allocatable size is 16/24/32 bytes.
Even a request for zero bytes (i.e., malloc(0)) returns a
pointer to something of the minimum allocatable size.
Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes
8-byte size_t: 2^63 - 16 bytes
It is assumed that (possibly signed) size_t bit values suffice to
represent chunk sizes. `Possibly signed' is due to the fact
that `size_t' may be defined on a system as either a signed or
an unsigned type. To be conservative, values that would appear
as negative numbers are avoided.
Requests for sizes with a negative sign bit will return a
minimum-sized chunk.
Maximum overhead wastage per allocated chunk: normally 15 bytes
Alignment demands, plus the minimum allocatable size restriction
make the normal worst-case wastage 15 bytes (i.e., up to 15
more bytes will be allocated than were requested in malloc), with
two exceptions:
1. Because requests for zero bytes allocate non-zero space,
the worst case wastage for a request of zero bytes is 24 bytes.
2. For requests >= mmap_threshold that are serviced via
mmap(), the worst case wastage is 8 bytes plus the remainder
from a system page (the minimal mmap unit); typically 4096 bytes.
* Limitations
Here are some features that are NOT currently supported
* No automated mechanism for fully checking that all accesses
to malloced memory stay within their bounds.
* No support for compaction.
* Synopsis of compile-time options:
People have reported using previous versions of this malloc on all
versions of Unix, sometimes by tweaking some of the defines
below. It has been tested most extensively on Solaris and
Linux. People have also reported adapting this malloc for use in
stand-alone embedded systems.
The implementation is in straight, hand-tuned ANSI C. Among other
consequences, it uses a lot of macros. Because of this, to be at
all usable, this code should be compiled using an optimizing compiler
(for example gcc -O2) that can simplify expressions and control
paths.
__STD_C (default: derived from C compiler defines)
Nonzero if using ANSI-standard C compiler, a C++ compiler, or
a C compiler sufficiently close to ANSI to get away with it.
MALLOC_DEBUG (default: NOT defined)
Define to enable debugging. Adds fairly extensive assertion-based
checking to help track down memory errors, but noticeably slows down
execution.
MALLOC_HOOKS (default: NOT defined)
Define to enable support run-time replacement of the allocation
functions through user-defined `hooks'.
REALLOC_ZERO_BYTES_FREES (default: defined)
Define this if you think that realloc(p, 0) should be equivalent
to free(p). (The C standard requires this behaviour, therefore
it is the default.) Otherwise, since malloc returns a unique
pointer for malloc(0), so does realloc(p, 0).
HAVE_MEMCPY (default: defined)
Define if you are not otherwise using ANSI STD C, but still
have memcpy and memset in your C library and want to use them.
Otherwise, simple internal versions are supplied.
USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
Define as 1 if you want the C library versions of memset and
memcpy called in realloc and calloc (otherwise macro versions are used).
At least on some platforms, the simple macro versions usually
outperform libc versions.
HAVE_MMAP (default: defined as 1)
Define to non-zero to optionally make malloc() use mmap() to
allocate very large blocks.
HAVE_MREMAP (default: defined as 0 unless Linux libc set)
Define to non-zero to optionally make realloc() use mremap() to
reallocate very large blocks.
USE_ARENAS (default: the same as HAVE_MMAP)
Enable support for multiple arenas, allocated using mmap().
malloc_getpagesize (default: derived from system #includes)
Either a constant or routine call returning the system page size.
HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
Optionally define if you are on a system with a /usr/include/malloc.h
that declares struct mallinfo. It is not at all necessary to
define this even if you do, but will ensure consistency.
INTERNAL_SIZE_T (default: size_t)
Define to a 32-bit type (probably `unsigned int') if you are on a
64-bit machine, yet do not want or need to allow malloc requests of
greater than 2^31 to be handled. This saves space, especially for
very small chunks.
_LIBC (default: NOT defined)
Defined only when compiled as part of the Linux libc/glibc.
Also note that there is some odd internal name-mangling via defines
(for example, internally, `malloc' is named `mALLOc') needed
when compiling in this case. These look funny but don't otherwise
affect anything.
LACKS_UNISTD_H (default: undefined)
Define this if your system does not have a <unistd.h>.
MORECORE (default: sbrk)
The name of the routine to call to obtain more memory from the system.
MORECORE_FAILURE (default: -1)
The value returned upon failure of MORECORE.
MORECORE_CLEARS (default 1)
The degree to which the routine mapped to MORECORE zeroes out
memory: never (0), only for newly allocated space (1) or always
(2). The distinction between (1) and (2) is necessary because on
some systems, if the application first decrements and then
increments the break value, the contents of the reallocated space
are unspecified.
DEFAULT_TRIM_THRESHOLD
DEFAULT_TOP_PAD
DEFAULT_MMAP_THRESHOLD
DEFAULT_MMAP_MAX
Default values of tunable parameters (described in detail below)
controlling interaction with host system routines (sbrk, mmap, etc).
These values may also be changed dynamically via mallopt(). The
preset defaults are those that give best performance for typical
programs/systems.
DEFAULT_CHECK_ACTION
When the standard debugging hooks are in place, and a pointer is
detected as corrupt, do nothing (0), print an error message (1),
or call abort() (2).
*/
/*
* Compile-time options for multiple threads:
USE_PTHREADS, USE_THR, USE_SPROC
Define one of these as 1 to select the thread interface:
POSIX threads, Solaris threads or SGI sproc's, respectively.
If none of these is defined as non-zero, you get a `normal'
malloc implementation which is not thread-safe. Support for
multiple threads requires HAVE_MMAP=1. As an exception, when
compiling for GNU libc, i.e. when _LIBC is defined, then none of
the USE_... symbols have to be defined.
HEAP_MIN_SIZE
HEAP_MAX_SIZE
When thread support is enabled, additional `heap's are created
with mmap calls. These are limited in size; HEAP_MIN_SIZE should
be a multiple of the page size, while HEAP_MAX_SIZE must be a power
of two for alignment reasons. HEAP_MAX_SIZE should be at least
twice as large as the mmap threshold.
THREAD_STATS
When this is defined as non-zero, some statistics on mutex locking
are computed.
*/
/* Preliminaries */
#ifndef __STD_C
#if defined (__STDC__)
#define __STD_C 1
#else
#if __cplusplus
#define __STD_C 1
#else
#define __STD_C 0
#endif /*__cplusplus*/
#endif /*__STDC__*/
#endif /*__STD_C*/
#ifndef Void_t
#if __STD_C
#define Void_t void
#else
#define Void_t char
#endif
#endif /*Void_t*/
#define _GNU_SOURCE
#include <features.h>
#define _LIBC 1
#define NOT_IN_libc 1
#if __STD_C
# include <stddef.h> /* for size_t */
# if defined _LIBC || defined MALLOC_HOOKS
# include <stdlib.h> /* for getenv(), abort() */
# endif
#else
# include <sys/types.h>
# if defined _LIBC || defined MALLOC_HOOKS
extern char* getenv();
# endif
#endif
/* newlib modifications */
#include <libc-symbols.h>
#include <sys/types.h>
extern void __pthread_initialize (void) __attribute__((weak));
extern void *__mmap (void *__addr, size_t __len, int __prot,
int __flags, int __fd, off_t __offset);
extern int __munmap (void *__addr, size_t __len);
extern void *__mremap (void *__addr, size_t __old_len, size_t __new_len,
int __may_move);
extern int __getpagesize (void);
#define __libc_enable_secure 1
/* Macros for handling mutexes and thread-specific data. This is
included early, because some thread-related header files (such as
pthread.h) should be included before any others. */
#include <bits/libc-lock.h>
#include "thread-m.h"
void *(*__malloc_internal_tsd_get) (enum __libc_tsd_key_t) = NULL;
int (*__malloc_internal_tsd_set) (enum __libc_tsd_key_t,
__const void *) = NULL;
weak_alias(__malloc_internal_tsd_get, __libc_internal_tsd_get)
weak_alias(__malloc_internal_tsd_set, __libc_internal_tsd_set)
#ifdef __cplusplus
extern "C" {
#endif
#include <errno.h>
#include <stdio.h> /* needed for malloc_stats */
/*
Compile-time options
*/
/*
Debugging:
Because freed chunks may be overwritten with link fields, this
malloc will often die when freed memory is overwritten by user
programs. This can be very effective (albeit in an annoying way)
in helping track down dangling pointers.
If you compile with -DMALLOC_DEBUG, a number of assertion checks are
enabled that will catch more memory errors. You probably won't be
able to make much sense of the actual assertion errors, but they
should help you locate incorrectly overwritten memory. The
checking is fairly extensive, and will slow down execution
noticeably. Calling malloc_stats or mallinfo with MALLOC_DEBUG set will
attempt to check every non-mmapped allocated and free chunk in the
course of computing the summaries. (By nature, mmapped regions
cannot be checked very much automatically.)
Setting MALLOC_DEBUG may also be helpful if you are trying to modify
this code. The assertions in the check routines spell out in more
detail the assumptions and invariants underlying the algorithms.
*/
#if MALLOC_DEBUG
#include <assert.h>
#else
#define assert(x) ((void)0)
#endif
/*
INTERNAL_SIZE_T is the word-size used for internal bookkeeping
of chunk sizes. On a 64-bit machine, you can reduce malloc
overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'
at the expense of not being able to handle requests greater than
2^31. This limitation is hardly ever a concern; you are encouraged
to set this. However, the default version is the same as size_t.
*/
#ifndef INTERNAL_SIZE_T
#define INTERNAL_SIZE_T size_t
#endif
/*
REALLOC_ZERO_BYTES_FREES should be set if a call to realloc with
zero bytes should be the same as a call to free. The C standard
requires this. Otherwise, since this malloc returns a unique pointer
for malloc(0), so does realloc(p, 0).
*/
#define REALLOC_ZERO_BYTES_FREES
/*
HAVE_MEMCPY should be defined if you are not otherwise using
ANSI STD C, but still have memcpy and memset in your C library
and want to use them in calloc and realloc. Otherwise simple
macro versions are defined here.
USE_MEMCPY should be defined as 1 if you actually want to
have memset and memcpy called. People report that the macro
versions are often enough faster than libc versions on many
systems that it is better to use them.
*/
#define HAVE_MEMCPY 1
#ifndef USE_MEMCPY
#ifdef HAVE_MEMCPY
#define USE_MEMCPY 1
#else
#define USE_MEMCPY 0
#endif
#endif
#if (__STD_C || defined(HAVE_MEMCPY))
#if __STD_C
void* memset(void*, int, size_t);
void* memcpy(void*, const void*, size_t);
void* memmove(void*, const void*, size_t);
#else
Void_t* memset();
Void_t* memcpy();
Void_t* memmove();
#endif
#endif
/* The following macros are only invoked with (2n+1)-multiples of
INTERNAL_SIZE_T units, with a positive integer n. This is exploited
for fast inline execution when n is small. If the regions to be
copied do overlap, the destination lies always _below_ the source. */
#if USE_MEMCPY
#define MALLOC_ZERO(charp, nbytes) \
do { \
INTERNAL_SIZE_T mzsz = (nbytes); \
if(mzsz <= 9*sizeof(mzsz)) { \
INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \
if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; \
if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; \
if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; }}} \
*mz++ = 0; \
*mz++ = 0; \
*mz = 0; \
} else memset((charp), 0, mzsz); \
} while(0)
/* If the regions overlap, dest is always _below_ src. */
#define MALLOC_COPY(dest,src,nbytes,overlap) \
do { \
INTERNAL_SIZE_T mcsz = (nbytes); \
if(mcsz <= 9*sizeof(mcsz)) { \
INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \
INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \
if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; }}} \
*mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
*mcdst = *mcsrc ; \
} else if(overlap) \
memmove(dest, src, mcsz); \
else \
memcpy(dest, src, mcsz); \
} while(0)
#else /* !USE_MEMCPY */
/* Use Duff's device for good zeroing/copying performance. */
#define MALLOC_ZERO(charp, nbytes) \
do { \
INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \
long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
switch (mctmp) { \
case 0: for(;;) { *mzp++ = 0; \
case 7: *mzp++ = 0; \
case 6: *mzp++ = 0; \
case 5: *mzp++ = 0; \
case 4: *mzp++ = 0; \
case 3: *mzp++ = 0; \
case 2: *mzp++ = 0; \
case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \
} \
} while(0)
/* If the regions overlap, dest is always _below_ src. */
#define MALLOC_COPY(dest,src,nbytes,overlap) \
do { \
INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \
INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \
long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
switch (mctmp) { \
case 0: for(;;) { *mcdst++ = *mcsrc++; \
case 7: *mcdst++ = *mcsrc++; \
case 6: *mcdst++ = *mcsrc++; \
case 5: *mcdst++ = *mcsrc++; \
case 4: *mcdst++ = *mcsrc++; \
case 3: *mcdst++ = *mcsrc++; \
case 2: *mcdst++ = *mcsrc++; \
case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \
} \
} while(0)
#endif
#ifndef LACKS_UNISTD_H
# include <unistd.h>
#endif
/*
Define HAVE_MMAP to optionally make malloc() use mmap() to allocate
very large blocks. These will be returned to the operating system
immediately after a free(). HAVE_MMAP is also a prerequisite to
support multiple `arenas' (see USE_ARENAS below).
*/
#ifndef HAVE_MMAP
# ifdef _POSIX_MAPPED_FILES
# define HAVE_MMAP 1
# endif
#endif
/*
Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
large blocks. This is currently only possible on Linux with
kernel versions newer than 1.3.77.
*/
#ifndef HAVE_MREMAP
#define HAVE_MREMAP defined(__linux__)
#endif
/* Define USE_ARENAS to enable support for multiple `arenas'. These
are allocated using mmap(), are necessary for threads and
occasionally useful to overcome address space limitations affecting
sbrk(). */
#ifndef USE_ARENAS
#define USE_ARENAS HAVE_MMAP
#endif
#if HAVE_MMAP
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
#define MAP_ANONYMOUS MAP_ANON
#endif
#if !defined(MAP_FAILED)
#define MAP_FAILED ((char*)-1)
#endif
#ifndef MAP_NORESERVE
# ifdef MAP_AUTORESRV
# define MAP_NORESERVE MAP_AUTORESRV
# else
# define MAP_NORESERVE 0
# endif
#endif
#endif /* HAVE_MMAP */
/*
Access to system page size. To the extent possible, this malloc
manages memory from the system in page-size units.
The following mechanics for getpagesize were adapted from
bsd/gnu getpagesize.h
*/
#ifndef malloc_getpagesize
# ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
# ifndef _SC_PAGE_SIZE
# define _SC_PAGE_SIZE _SC_PAGESIZE
# endif
# endif
# ifdef _SC_PAGE_SIZE
# define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
# else
# if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
extern size_t getpagesize();
# define malloc_getpagesize getpagesize()
# else
# include <sys/param.h>
# ifdef EXEC_PAGESIZE
# define malloc_getpagesize EXEC_PAGESIZE
# else
# ifdef NBPG
# ifndef CLSIZE
# define malloc_getpagesize NBPG
# else
# define malloc_getpagesize (NBPG * CLSIZE)
# endif
# else
# ifdef NBPC
# define malloc_getpagesize NBPC
# else
# ifdef PAGESIZE
# define malloc_getpagesize PAGESIZE
# else
# define malloc_getpagesize (4096) /* just guess */
# endif
# endif
# endif
# endif
# endif
# endif
#endif
/*
This version of malloc supports the standard SVID/XPG mallinfo
routine that returns a struct containing the same kind of
information you can get from malloc_stats. It should work on
any SVID/XPG compliant system that has a /usr/include/malloc.h
defining struct mallinfo. (If you'd like to install such a thing
yourself, cut out the preliminary declarations as described above
and below and save them in a malloc.h file. But there's no
compelling reason to bother to do this.)
The main declaration needed is the mallinfo struct that is returned
(by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
bunch of fields, most of which are not even meaningful in this
version of malloc. Some of these fields are are instead filled by
mallinfo() with other numbers that might possibly be of interest.
HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
/usr/include/malloc.h file that includes a declaration of struct
mallinfo. If so, it is included; else an SVID2/XPG2 compliant
version is declared below. These must be precisely the same for
mallinfo() to work.
*/
/* #define HAVE_USR_INCLUDE_MALLOC_H */
#if HAVE_USR_INCLUDE_MALLOC_H
# include "/usr/include/malloc.h"
#else
# ifdef _LIBC
# include "malloc.h"
# else
# include "ptmalloc.h"
# endif
#endif
#include <bp-checks.h>
#ifndef DEFAULT_TRIM_THRESHOLD
#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
#endif
/*
M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
to keep before releasing via malloc_trim in free().
Automatic trimming is mainly useful in long-lived programs.
Because trimming via sbrk can be slow on some systems, and can
sometimes be wasteful (in cases where programs immediately
afterward allocate more large chunks) the value should be high
enough so that your overall system performance would improve by
releasing.
The trim threshold and the mmap control parameters (see below)
can be traded off with one another. Trimming and mmapping are
two different ways of releasing unused memory back to the
system. Between these two, it is often possible to keep
system-level demands of a long-lived program down to a bare
minimum. For example, in one test suite of sessions measuring
the XF86 X server on Linux, using a trim threshold of 128K and a
mmap threshold of 192K led to near-minimal long term resource
consumption.
If you are using this malloc in a long-lived program, it should
pay to experiment with these values. As a rough guide, you
might set to a value close to the average size of a process
(program) running on your system. Releasing this much memory
would allow such a process to run in memory. Generally, it's
worth it to tune for trimming rather than memory mapping when a
program undergoes phases where several large chunks are
allocated and released in ways that can reuse each other's
storage, perhaps mixed with phases where there are no such
chunks at all. And in well-behaved long-lived programs,
controlling release of large blocks via trimming versus mapping
is usually faster.
However, in most programs, these parameters serve mainly as
protection against the system-level effects of carrying around
massive amounts of unneeded memory. Since frequent calls to
sbrk, mmap, and munmap otherwise degrade performance, the default
parameters are set to relatively high values that serve only as
safeguards.
The default trim value is high enough to cause trimming only in
fairly extreme (by current memory consumption standards) cases.
It must be greater than page size to have any useful effect. To
disable trimming completely, you can set to (unsigned long)(-1);
*/
#ifndef DEFAULT_TOP_PAD
#define DEFAULT_TOP_PAD (0)
#endif
/*
M_TOP_PAD is the amount of extra `padding' space to allocate or
retain whenever sbrk is called. It is used in two ways internally:
* When sbrk is called to extend the top of the arena to satisfy
a new malloc request, this much padding is added to the sbrk
request.
* When malloc_trim is called automatically from free(),
it is used as the `pad' argument.
In both cases, the actual amount of padding is rounded
so that the end of the arena is always a system page boundary.
The main reason for using padding is to avoid calling sbrk so
often. Having even a small pad greatly reduces the likelihood
that nearly every malloc request during program start-up (or
after trimming) will invoke sbrk, which needlessly wastes
time.
Automatic rounding-up to page-size units is normally sufficient
to avoid measurable overhead, so the default is 0. However, in
systems where sbrk is relatively slow, it can pay to increase
this value, at the expense of carrying around more memory than
the program needs.
*/
#ifndef DEFAULT_MMAP_THRESHOLD
#define DEFAULT_MMAP_THRESHOLD (128 * 1024)
#endif
/*
M_MMAP_THRESHOLD is the request size threshold for using mmap()
to service a request. Requests of at least this size that cannot
be allocated using already-existing space will be serviced via mmap.
(If enough normal freed space already exists it is used instead.)
Using mmap segregates relatively large chunks of memory so that
they can be individually obtained and released from the host
system. A request serviced through mmap is never reused by any
other request (at least not directly; the system may just so
happen to remap successive requests to the same locations).
Segregating space in this way has the benefit that mmapped space
can ALWAYS be individually released back to the system, which
helps keep the system level memory demands of a long-lived
program low. Mapped memory can never become `locked' between
other chunks, as can happen with normally allocated chunks, which
menas that even trimming via malloc_trim would not release them.
However, it has the disadvantages that:
1. The space cannot be reclaimed, consolidated, and then
used to service later requests, as happens with normal chunks.
2. It can lead to more wastage because of mmap page alignment
requirements
3. It causes malloc performance to be more dependent on host
system memory management support routines which may vary in
implementation quality and may impose arbitrary
limitations. Generally, servicing a request via normal
malloc steps is faster than going through a system's mmap.
All together, these considerations should lead you to use mmap
only for relatively large requests.
*/
#ifndef DEFAULT_MMAP_MAX
#if HAVE_MMAP
#define DEFAULT_MMAP_MAX (1024)
#else
#define DEFAULT_MMAP_MAX (0)
#endif
#endif
/*
M_MMAP_MAX is the maximum number of requests to simultaneously
service using mmap. This parameter exists because:
1. Some systems have a limited number of internal tables for
use by mmap.
2. In most systems, overreliance on mmap can degrade overall
performance.
3. If a program allocates many large regions, it is probably
better off using normal sbrk-based allocation routines that
can reclaim and reallocate normal heap memory. Using a
small value allows transition into this mode after the
first few allocations.
Setting to 0 disables all use of mmap. If HAVE_MMAP is not set,
the default value is 0, and attempts to set it to non-zero values
in mallopt will fail.
*/
#ifndef DEFAULT_CHECK_ACTION
#define DEFAULT_CHECK_ACTION 1
#endif
/* What to do if the standard debugging hooks are in place and a
corrupt pointer is detected: do nothing (0), print an error message
(1), or call abort() (2). */
#define HEAP_MIN_SIZE (32*1024)
#define HEAP_MAX_SIZE (1024*1024) /* must be a power of two */
/* HEAP_MIN_SIZE and HEAP_MAX_SIZE limit the size of mmap()ed heaps
that are dynamically created for multi-threaded programs. The
maximum size must be a power of two, for fast determination of
which heap belongs to a chunk. It should be much larger than
the mmap threshold, so that requests with a size just below that
threshold can be fulfilled without creating too many heaps.
*/
#ifndef THREAD_STATS
#define THREAD_STATS 0
#endif
/* If THREAD_STATS is non-zero, some statistics on mutex locking are
computed. */
/* Macro to set errno. */
#ifndef __set_errno
# define __set_errno(val) errno = (val)
#endif
/* On some platforms we can compile internal, not exported functions better.
Let the environment provide a macro and define it to be empty if it
is not available. */
#ifndef internal_function
# define internal_function
#endif
/*
Special defines for the Linux/GNU C library.
*/
#ifdef _LIBC
#if __STD_C
Void_t * __default_morecore (ptrdiff_t);
Void_t *(*__morecore)(ptrdiff_t) = __default_morecore;
#else
Void_t * __default_morecore ();
Void_t *(*__morecore)() = __default_morecore;
#endif
#define MORECORE (*__morecore)
#define MORECORE_FAILURE 0
#ifndef MORECORE_CLEARS
#define MORECORE_CLEARS 1
#endif
static size_t __libc_pagesize;
#define access __access
#define mmap __mmap
#define munmap __munmap
#define mremap __mremap
#define mprotect __mprotect
#undef malloc_getpagesize
#define malloc_getpagesize __libc_pagesize
#else /* _LIBC */
#if __STD_C
extern Void_t* sbrk(ptrdiff_t);
#else
extern Void_t* sbrk();
#endif
#ifndef MORECORE
#define MORECORE sbrk
#endif
#ifndef MORECORE_FAILURE
#define MORECORE_FAILURE -1
#endif
#ifndef MORECORE_CLEARS
#define MORECORE_CLEARS 1
#endif
#endif /* _LIBC */
#ifdef _LIBC
#define cALLOc __libc_calloc
#define fREe __libc_free
#define mALLOc __libc_malloc
#define mEMALIGn __libc_memalign
#define rEALLOc __libc_realloc
#define vALLOc __libc_valloc
#define pvALLOc __libc_pvalloc
#define mALLINFo __libc_mallinfo
#define mALLOPt __libc_mallopt
#define mALLOC_STATs __malloc_stats
#define mALLOC_USABLE_SIZe __malloc_usable_size
#define mALLOC_TRIm __malloc_trim
#define mALLOC_GET_STATe __malloc_get_state
#define mALLOC_SET_STATe __malloc_set_state
#else
#define cALLOc calloc
#define fREe free
#define mALLOc malloc
#define mEMALIGn memalign
#define rEALLOc realloc
#define vALLOc valloc
#define pvALLOc pvalloc
#define mALLINFo mallinfo
#define mALLOPt mallopt
#define mALLOC_STATs malloc_stats
#define mALLOC_USABLE_SIZe malloc_usable_size
#define mALLOC_TRIm malloc_trim
#define mALLOC_GET_STATe malloc_get_state
#define mALLOC_SET_STATe malloc_set_state
#endif
/* Public routines */
#if __STD_C
#ifndef _LIBC
void ptmalloc_init(void);
#endif
Void_t* mALLOc(size_t);
void fREe(Void_t*);
Void_t* rEALLOc(Void_t*, size_t);
Void_t* mEMALIGn(size_t, size_t);
Void_t* vALLOc(size_t);
Void_t* pvALLOc(size_t);
Void_t* cALLOc(size_t, size_t);
void cfree(Void_t*);
int mALLOC_TRIm(size_t);
size_t mALLOC_USABLE_SIZe(Void_t*);
void mALLOC_STATs(void);
int mALLOPt(int, int);
struct mallinfo mALLINFo(void);
Void_t* mALLOC_GET_STATe(void);
int mALLOC_SET_STATe(Void_t*);
#else /* !__STD_C */
#ifndef _LIBC
void ptmalloc_init();
#endif
Void_t* mALLOc();
void fREe();
Void_t* rEALLOc();
Void_t* mEMALIGn();
Void_t* vALLOc();
Void_t* pvALLOc();
Void_t* cALLOc();
void cfree();
int mALLOC_TRIm();
size_t mALLOC_USABLE_SIZe();
void mALLOC_STATs();
int mALLOPt();
struct mallinfo mALLINFo();
Void_t* mALLOC_GET_STATe();
int mALLOC_SET_STATe();
#endif /* __STD_C */
#ifdef __cplusplus
} /* end of extern "C" */
#endif
#if !defined(NO_THREADS) && !HAVE_MMAP
"Can't have threads support without mmap"
#endif
#if USE_ARENAS && !HAVE_MMAP
"Can't have multiple arenas without mmap"
#endif
/*
Type declarations
*/
struct malloc_chunk
{
INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */
INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */
struct malloc_chunk* fd; /* double links -- used only if free. */
struct malloc_chunk* bk;
};
typedef struct malloc_chunk* mchunkptr;
/*
malloc_chunk details:
(The following includes lightly edited explanations by Colin Plumb.)
Chunks of memory are maintained using a `boundary tag' method as
described in e.g., Knuth or Standish. (See the paper by Paul
Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
survey of such techniques.) Sizes of free chunks are stored both
in the front of each chunk and at the end. This makes
consolidating fragmented chunks into bigger chunks very fast. The
size fields also hold bits representing whether chunks are free or
in use.
An allocated chunk looks like this:
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of previous chunk, if allocated | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of chunk, in bytes |P|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| User data starts here... .
. .
. (malloc_usable_space() bytes) .
. |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of chunk |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where "chunk" is the front of the chunk for the purpose of most of
the malloc code, but "mem" is the pointer that is returned to the
user. "Nextchunk" is the beginning of the next contiguous chunk.
Chunks always begin on even word boundaries, so the mem portion
(which is returned to the user) is also on an even word boundary, and
thus double-word aligned.
Free chunks are stored in circular doubly-linked lists, and look like this:
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of previous chunk |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
`head:' | Size of chunk, in bytes |P|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Forward pointer to next chunk in list |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Back pointer to previous chunk in list |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unused space (may be 0 bytes long) .
. .
. |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
`foot:' | Size of chunk, in bytes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The P (PREV_INUSE) bit, stored in the unused low-order bit of the
chunk size (which is always a multiple of two words), is an in-use
bit for the *previous* chunk. If that bit is *clear*, then the
word before the current chunk size contains the previous chunk
size, and can be used to find the front of the previous chunk.
(The very first chunk allocated always has this bit set,
preventing access to non-existent (or non-owned) memory.)
Note that the `foot' of the current chunk is actually represented
as the prev_size of the NEXT chunk. (This makes it easier to
deal with alignments etc).
The two exceptions to all this are
1. The special chunk `top', which doesn't bother using the
trailing size field since there is no
next contiguous chunk that would have to index off it. (After
initialization, `top' is forced to always exist. If it would
become less than MINSIZE bytes long, it is replenished via
malloc_extend_top.)
2. Chunks allocated via mmap, which have the second-lowest-order
bit (IS_MMAPPED) set in their size fields. Because they are
never merged or traversed from any other chunk, they have no
foot size or inuse information.
Available chunks are kept in any of several places (all declared below):
* `av': An array of chunks serving as bin headers for consolidated
chunks. Each bin is doubly linked. The bins are approximately
proportionally (log) spaced. There are a lot of these bins
(128). This may look excessive, but works very well in
practice. All procedures maintain the invariant that no
consolidated chunk physically borders another one. Chunks in
bins are kept in size order, with ties going to the
approximately least recently used chunk.
The chunks in each bin are maintained in decreasing sorted order by
size. This is irrelevant for the small bins, which all contain
the same-sized chunks, but facilitates best-fit allocation for
larger chunks. (These lists are just sequential. Keeping them in
order almost never requires enough traversal to warrant using
fancier ordered data structures.) Chunks of the same size are
linked with the most recently freed at the front, and allocations
are taken from the back. This results in LRU or FIFO allocation
order, which tends to give each chunk an equal opportunity to be
consolidated with adjacent freed chunks, resulting in larger free
chunks and less fragmentation.
* `top': The top-most available chunk (i.e., the one bordering the
end of available memory) is treated specially. It is never
included in any bin, is used only if no other chunk is
available, and is released back to the system if it is very
large (see M_TRIM_THRESHOLD).
* `last_remainder': A bin holding only the remainder of the
most recently split (non-top) chunk. This bin is checked
before other non-fitting chunks, so as to provide better
locality for runs of sequentially allocated chunks.
* Implicitly, through the host system's memory mapping tables.
If supported, requests greater than a threshold are usually
serviced via calls to mmap, and then later released via munmap.
*/
/*
Bins
The bins are an array of pairs of pointers serving as the
heads of (initially empty) doubly-linked lists of chunks, laid out
in a way so that each pair can be treated as if it were in a
malloc_chunk. (This way, the fd/bk offsets for linking bin heads
and chunks are the same).
Bins for sizes < 512 bytes contain chunks of all the same size, spaced
8 bytes apart. Larger bins are approximately logarithmically
spaced. (See the table below.)
Bin layout:
64 bins of size 8
32 bins of size 64
16 bins of size 512
8 bins of size 4096
4 bins of size 32768
2 bins of size 262144
1 bin of size what's left
There is actually a little bit of slop in the numbers in bin_index
for the sake of speed. This makes no difference elsewhere.
The special chunks `top' and `last_remainder' get their own bins,
(this is implemented via yet more trickery with the av array),
although `top' is never properly linked to its bin since it is
always handled specially.
*/
#define NAV 128 /* number of bins */
typedef struct malloc_chunk* mbinptr;
/* An arena is a configuration of malloc_chunks together with an array
of bins. With multiple threads, it must be locked via a mutex
before changing its data structures. One or more `heaps' are
associated with each arena, except for the main_arena, which is
associated only with the `main heap', i.e. the conventional free
store obtained with calls to MORECORE() (usually sbrk). The `av'
array is never mentioned directly in the code, but instead used via
bin access macros. */
typedef struct _arena {
mbinptr av[2*NAV + 2];
struct _arena *next;
size_t size;
#if THREAD_STATS
long stat_lock_direct, stat_lock_loop, stat_lock_wait;
#endif
mutex_t mutex;
} arena;
/* A heap is a single contiguous memory region holding (coalesceable)
malloc_chunks. It is allocated with mmap() and always starts at an
address aligned to HEAP_MAX_SIZE. Not used unless compiling with
USE_ARENAS. */
typedef struct _heap_info {
arena *ar_ptr; /* Arena for this heap. */
struct _heap_info *prev; /* Previous heap. */
size_t size; /* Current size in bytes. */
size_t pad; /* Make sure the following data is properly aligned. */
} heap_info;
/*
Static functions (forward declarations)
*/
#if __STD_C
static void chunk_free(arena *ar_ptr, mchunkptr p) internal_function;
static mchunkptr chunk_alloc(arena *ar_ptr, INTERNAL_SIZE_T size)
internal_function;
static mchunkptr chunk_realloc(arena *ar_ptr, mchunkptr oldp,
INTERNAL_SIZE_T oldsize, INTERNAL_SIZE_T nb)
internal_function;
static mchunkptr chunk_align(arena *ar_ptr, INTERNAL_SIZE_T nb,
size_t alignment) internal_function;
static int main_trim(size_t pad) internal_function;
#if USE_ARENAS
static int heap_trim(heap_info *heap, size_t pad) internal_function;
#endif
#if defined _LIBC || defined MALLOC_HOOKS
static Void_t* malloc_check(size_t sz, const Void_t *caller);
static void free_check(Void_t* mem, const Void_t *caller);
static Void_t* realloc_check(Void_t* oldmem, size_t bytes,
const Void_t *caller);
static Void_t* memalign_check(size_t alignment, size_t bytes,
const Void_t *caller);
#ifndef NO_THREADS
static Void_t* malloc_starter(size_t sz, const Void_t *caller);
static void free_starter(Void_t* mem, const Void_t *caller);
static Void_t* malloc_atfork(size_t sz, const Void_t *caller);
static void free_atfork(Void_t* mem, const Void_t *caller);
#endif
#endif
#else
static void chunk_free();
static mchunkptr chunk_alloc();
static mchunkptr chunk_realloc();
static mchunkptr chunk_align();
static int main_trim();
#if USE_ARENAS
static int heap_trim();
#endif
#if defined _LIBC || defined MALLOC_HOOKS
static Void_t* malloc_check();
static void free_check();
static Void_t* realloc_check();
static Void_t* memalign_check();
#ifndef NO_THREADS
static Void_t* malloc_starter();
static void free_starter();
static Void_t* malloc_atfork();
static void free_atfork();
#endif
#endif
#endif
/* sizes, alignments */
#define SIZE_SZ (sizeof(INTERNAL_SIZE_T))
/* Allow the default to be overwritten on the compiler command line. */
#ifndef MALLOC_ALIGNMENT
# define MALLOC_ALIGNMENT (SIZE_SZ + SIZE_SZ)
#endif
#define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
#define MINSIZE (sizeof(struct malloc_chunk))
/* conversion from malloc headers to user pointers, and back */
#define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ))
#define mem2chunk(mem) chunk_at_offset((mem), -2*SIZE_SZ)
/* pad request bytes into a usable size, return non-zero on overflow */
#define request2size(req, nb) \
((nb = (req) + (SIZE_SZ + MALLOC_ALIGN_MASK)),\
((long)nb <= 0 || nb < (INTERNAL_SIZE_T) (req) \
? (__set_errno (ENOMEM), 1) \
: ((nb < (MINSIZE + MALLOC_ALIGN_MASK) \
? (nb = MINSIZE) : (nb &= ~MALLOC_ALIGN_MASK)), 0)))
/* Check if m has acceptable alignment */
#define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0)
/*
Physical chunk operations
*/
/* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
#define PREV_INUSE 0x1UL
/* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
#define IS_MMAPPED 0x2UL
/* Bits to mask off when extracting size */
#define SIZE_BITS (PREV_INUSE|IS_MMAPPED)
/* Ptr to next physical malloc_chunk. */
#define next_chunk(p) chunk_at_offset((p), (p)->size & ~PREV_INUSE)
/* Ptr to previous physical malloc_chunk */
#define prev_chunk(p) chunk_at_offset((p), -(p)->prev_size)
/* Treat space at ptr + offset as a chunk */
#define chunk_at_offset(p, s) BOUNDED_1((mchunkptr)(((char*)(p)) + (s)))
/*
Dealing with use bits
*/
/* extract p's inuse bit */
#define inuse(p) (next_chunk(p)->size & PREV_INUSE)
/* extract inuse bit of previous chunk */
#define prev_inuse(p) ((p)->size & PREV_INUSE)
/* check for mmap()'ed chunk */
#define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)
/* set/clear chunk as in use without otherwise disturbing */
#define set_inuse(p) (next_chunk(p)->size |= PREV_INUSE)
#define clear_inuse(p) (next_chunk(p)->size &= ~PREV_INUSE)
/* check/set/clear inuse bits in known places */
#define inuse_bit_at_offset(p, s) \
(chunk_at_offset((p), (s))->size & PREV_INUSE)
#define set_inuse_bit_at_offset(p, s) \
(chunk_at_offset((p), (s))->size |= PREV_INUSE)
#define clear_inuse_bit_at_offset(p, s) \
(chunk_at_offset((p), (s))->size &= ~(PREV_INUSE))
/*
Dealing with size fields
*/
/* Get size, ignoring use bits */
#define chunksize(p) ((p)->size & ~(SIZE_BITS))
/* Set size at head, without disturbing its use bit */
#define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s)))
/* Set size/use ignoring previous bits in header */
#define set_head(p, s) ((p)->size = (s))
/* Set size at footer (only when chunk is not in use) */
#define set_foot(p, s) (chunk_at_offset(p, s)->prev_size = (s))
/* access macros */
#define bin_at(a, i) BOUNDED_1(_bin_at(a, i))
#define _bin_at(a, i) ((mbinptr)((char*)&(((a)->av)[2*(i)+2]) - 2*SIZE_SZ))
#define init_bin(a, i) ((a)->av[2*(i)+2] = (a)->av[2*(i)+3] = bin_at((a), (i)))
#define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(((arena*)0)->av[0])))
#define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(((arena*)0)->av[0])))
/*
The first 2 bins are never indexed. The corresponding av cells are instead
used for bookkeeping. This is not to save space, but to simplify
indexing, maintain locality, and avoid some initialization tests.
*/
#define binblocks(a) (bin_at(a,0)->size)/* bitvector of nonempty blocks */
#define top(a) (bin_at(a,0)->fd) /* The topmost chunk */
#define last_remainder(a) (bin_at(a,1)) /* remainder from last split */
/*
Because top initially points to its own bin with initial
zero size, thus forcing extension on the first malloc request,
we avoid having any special code in malloc to check whether
it even exists yet. But we still need to in malloc_extend_top.
*/
#define initial_top(a) ((mchunkptr)bin_at(a, 0))
/* field-extraction macros */
#define first(b) ((b)->fd)
#define last(b) ((b)->bk)
/*
Indexing into bins
*/
#define bin_index(sz) \
(((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3):\
((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6):\
((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9):\
((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12):\
((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15):\
((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18):\
126)
/*
bins for chunks < 512 are all spaced 8 bytes apart, and hold
identically sized chunks. This is exploited in malloc.
*/
#define MAX_SMALLBIN 63
#define MAX_SMALLBIN_SIZE 512
#define SMALLBIN_WIDTH 8
#define smallbin_index(sz) (((unsigned long)(sz)) >> 3)
/*
Requests are `small' if both the corresponding and the next bin are small
*/
#define is_small_request(nb) ((nb) < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH)
/*
To help compensate for the large number of bins, a one-level index
structure is used for bin-by-bin searching. `binblocks' is a
one-word bitvector recording whether groups of BINBLOCKWIDTH bins
have any (possibly) non-empty bins, so they can be skipped over
all at once during during traversals. The bits are NOT always
cleared as soon as all bins in a block are empty, but instead only
when all are noticed to be empty during traversal in malloc.
*/
#define BINBLOCKWIDTH 4 /* bins per block */
/* bin<->block macros */
#define idx2binblock(ix) ((unsigned)1 << ((ix) / BINBLOCKWIDTH))
#define mark_binblock(a, ii) (binblocks(a) |= idx2binblock(ii))
#define clear_binblock(a, ii) (binblocks(a) &= ~(idx2binblock(ii)))
/* Static bookkeeping data */
/* Helper macro to initialize bins */
#define IAV(i) _bin_at(&main_arena, i), _bin_at(&main_arena, i)
static arena main_arena = {
{
0, 0,
IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7),
IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15),
IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23),
IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31),
IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39),
IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47),
IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55),
IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63),
IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71),
IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79),
IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87),
IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95),
IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103),
IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111),
IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119),
IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127)
},
&main_arena, /* next */
0, /* size */
#if THREAD_STATS
0, 0, 0, /* stat_lock_direct, stat_lock_loop, stat_lock_wait */
#endif
MUTEX_INITIALIZER /* mutex */
};
#undef IAV
/* Thread specific data */
static tsd_key_t arena_key;
static mutex_t list_lock = MUTEX_INITIALIZER;
#if THREAD_STATS
static int stat_n_heaps;
#define THREAD_STAT(x) x
#else
#define THREAD_STAT(x) do ; while(0)
#endif
/* variables holding tunable values */
static unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD;
static unsigned long top_pad = DEFAULT_TOP_PAD;
static unsigned int n_mmaps_max = DEFAULT_MMAP_MAX;
static unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD;
static int check_action = DEFAULT_CHECK_ACTION;
/* The first value returned from sbrk */
static char* sbrk_base = (char*)(-1);
/* The maximum memory obtained from system via sbrk */
static unsigned long max_sbrked_mem;
/* The maximum via either sbrk or mmap (too difficult to track with threads) */
#ifdef NO_THREADS
static unsigned long max_total_mem;
#endif
/* The total memory obtained from system via sbrk */
#define sbrked_mem (main_arena.size)
/* Tracking mmaps */
static unsigned int n_mmaps;
static unsigned int max_n_mmaps;
static unsigned long mmapped_mem;
static unsigned long max_mmapped_mem;
/* Mapped memory in non-main arenas (reliable only for NO_THREADS). */
static unsigned long arena_mem;
#ifndef _LIBC
#define weak_variable
#else
/* In GNU libc we want the hook variables to be weak definitions to
avoid a problem with Emacs. */
#define weak_variable weak_function
#endif
/* Already initialized? */
int __malloc_initialized = -1;
#ifndef NO_THREADS
/* Magic value for the thread-specific arena pointer when
malloc_atfork() is in use. */
#define ATFORK_ARENA_PTR ((Void_t*)-1)
/* The following two functions are registered via thread_atfork() to
make sure that the mutexes remain in a consistent state in the
fork()ed version of a thread. Also adapt the malloc and free hooks
temporarily, because the `atfork' handler mechanism may use
malloc/free internally (e.g. in LinuxThreads). */
#if defined _LIBC || defined MALLOC_HOOKS
static __malloc_ptr_t (*save_malloc_hook) __MALLOC_P ((size_t __size,
const __malloc_ptr_t));
static void (*save_free_hook) __MALLOC_P ((__malloc_ptr_t __ptr,
const __malloc_ptr_t));
static Void_t* save_arena;
#endif
static void
ptmalloc_lock_all __MALLOC_P((void))
{
arena *ar_ptr;
(void)mutex_lock(&list_lock);
for(ar_ptr = &main_arena;;) {
(void)mutex_lock(&ar_ptr->mutex);
ar_ptr = ar_ptr->next;
if(ar_ptr == &main_arena) break;
}
#if defined _LIBC || defined MALLOC_HOOKS
save_malloc_hook = __malloc_hook;
save_free_hook = __free_hook;
__malloc_hook = malloc_atfork;
__free_hook = free_atfork;
/* Only the current thread may perform malloc/free calls now. */
tsd_getspecific(arena_key, save_arena);
tsd_setspecific(arena_key, ATFORK_ARENA_PTR);
#endif
}
static void
ptmalloc_unlock_all __MALLOC_P((void))
{
arena *ar_ptr;
#if defined _LIBC || defined MALLOC_HOOKS
tsd_setspecific(arena_key, save_arena);
__malloc_hook = save_malloc_hook;
__free_hook = save_free_hook;
#endif
for(ar_ptr = &main_arena;;) {
(void)mutex_unlock(&ar_ptr->mutex);
ar_ptr = ar_ptr->next;
if(ar_ptr == &main_arena) break;
}
(void)mutex_unlock(&list_lock);
}
static void
ptmalloc_init_all __MALLOC_P((void))
{
arena *ar_ptr;
#if defined _LIBC || defined MALLOC_HOOKS
tsd_setspecific(arena_key, save_arena);
__malloc_hook = save_malloc_hook;
__free_hook = save_free_hook;
#endif
for(ar_ptr = &main_arena;;) {
(void)mutex_init(&ar_ptr->mutex);
ar_ptr = ar_ptr->next;
if(ar_ptr == &main_arena) break;
}
(void)mutex_init(&list_lock);
}
#endif /* !defined NO_THREADS */
/* Initialization routine. */
#if defined(_LIBC)
#if 0
static void ptmalloc_init __MALLOC_P ((void)) __attribute__ ((constructor));
#endif
#ifdef _LIBC
#include <string.h>
extern char **environ;
static char *
internal_function
next_env_entry (char ***position)
{
char **current = *position;
char *result = NULL;
while (*current != NULL)
{
if (__builtin_expect ((*current)[0] == 'M', 0)
&& (*current)[1] == 'A'
&& (*current)[2] == 'L'
&& (*current)[3] == 'L'
&& (*current)[4] == 'O'
&& (*current)[5] == 'C'
&& (*current)[6] == '_')
{
result = &(*current)[7];
/* Save current position for next visit. */
*position = ++current;
break;
}
++current;
}
return result;
}
#endif
static void
ptmalloc_init __MALLOC_P((void))
#else
void
ptmalloc_init __MALLOC_P((void))
#endif
{
#if defined _LIBC || defined MALLOC_HOOKS
# if __STD_C
const char* s;
# else
char* s;
# endif
#endif
int secure;
if(__malloc_initialized >= 0) return;
__malloc_initialized = 0;
#ifdef _LIBC
__libc_pagesize = __getpagesize();
#endif
#ifndef NO_THREADS
#if defined _LIBC || defined MALLOC_HOOKS
/* With some threads implementations, creating thread-specific data
or initializing a mutex may call malloc() itself. Provide a
simple starter version (realloc() won't work). */
save_malloc_hook = __malloc_hook;
save_free_hook = __free_hook;
__malloc_hook = malloc_starter;
__free_hook = free_starter;
#endif
#ifdef _LIBC
/* Initialize the pthreads interface. */
if (__pthread_initialize != NULL)
__pthread_initialize();
#endif
#endif /* !defined NO_THREADS */
mutex_init(&main_arena.mutex);
mutex_init(&list_lock);
tsd_key_create(&arena_key, NULL);
tsd_setspecific(arena_key, (Void_t *)&main_arena);
thread_atfork(ptmalloc_lock_all, ptmalloc_unlock_all, ptmalloc_init_all);
#if defined _LIBC || defined MALLOC_HOOKS
#ifndef NO_THREADS
__malloc_hook = save_malloc_hook;
__free_hook = save_free_hook;
#endif
secure = __libc_enable_secure;
#ifdef _LIBC
s = NULL;
if (environ != NULL)
{
char **runp = environ;
char *envline;
while (__builtin_expect ((envline = next_env_entry (&runp)) != NULL, 0))
{
size_t len = strcspn (envline, "=");
if (envline[len] != '=')
/* This is a "MALLOC_" variable at the end of the string
without a '=' character. Ignore it since otherwise we
will access invalid memory below. */
continue;
switch (len)
{
case 6:
if (memcmp (envline, "CHECK_", 6) == 0)
s = &envline[7];
break;
case 8:
if (! secure && memcmp (envline, "TOP_PAD_", 8) == 0)
mALLOPt(M_TOP_PAD, atoi(&envline[9]));
break;
case 9:
if (! secure && memcmp (envline, "MMAP_MAX_", 9) == 0)
mALLOPt(M_MMAP_MAX, atoi(&envline[10]));
break;
case 15:
if (! secure)
{
if (memcmp (envline, "TRIM_THRESHOLD_", 15) == 0)
mALLOPt(M_TRIM_THRESHOLD, atoi(&envline[16]));
else if (memcmp (envline, "MMAP_THRESHOLD_", 15) == 0)
mALLOPt(M_MMAP_THRESHOLD, atoi(&envline[16]));
}
break;
default:
break;
}
}
}
#else
if (! secure)
{
if((s = getenv("MALLOC_TRIM_THRESHOLD_")))
mALLOPt(M_TRIM_THRESHOLD, atoi(s));
if((s = getenv("MALLOC_TOP_PAD_")))
mALLOPt(M_TOP_PAD, atoi(s));
if((s = getenv("MALLOC_MMAP_THRESHOLD_")))
mALLOPt(M_MMAP_THRESHOLD, atoi(s));
if((s = getenv("MALLOC_MMAP_MAX_")))
mALLOPt(M_MMAP_MAX, atoi(s));
}
s = getenv("MALLOC_CHECK_");
#endif
if(s) {
if(s[0]) mALLOPt(M_CHECK_ACTION, (int)(s[0] - '0'));
__malloc_check_init();
}
if(__malloc_initialize_hook != NULL)
(*__malloc_initialize_hook)();
#endif
__malloc_initialized = 1;
}
/* There are platforms (e.g. Hurd) with a link-time hook mechanism. */
#ifdef thread_atfork_static
thread_atfork_static(ptmalloc_lock_all, ptmalloc_unlock_all, \
ptmalloc_init_all)
#endif
#if defined _LIBC || defined MALLOC_HOOKS
/* Hooks for debugging versions. The initial hooks just call the
initialization routine, then do the normal work. */
static Void_t*
#if __STD_C
malloc_hook_ini(size_t sz, const __malloc_ptr_t caller)
#else
malloc_hook_ini(sz, caller)
size_t sz; const __malloc_ptr_t caller;
#endif
{
__malloc_hook = NULL;
ptmalloc_init();
return mALLOc(sz);
}
static Void_t*
#if __STD_C
realloc_hook_ini(Void_t* ptr, size_t sz, const __malloc_ptr_t caller)
#else
realloc_hook_ini(ptr, sz, caller)
Void_t* ptr; size_t sz; const __malloc_ptr_t caller;
#endif
{
__malloc_hook = NULL;
__realloc_hook = NULL;
ptmalloc_init();
return rEALLOc(ptr, sz);
}
static Void_t*
#if __STD_C
memalign_hook_ini(size_t alignment, size_t sz, const __malloc_ptr_t caller)
#else
memalign_hook_ini(alignment, sz, caller)
size_t alignment; size_t sz; const __malloc_ptr_t caller;
#endif
{
__memalign_hook = NULL;
ptmalloc_init();
return mEMALIGn(alignment, sz);
}
void weak_variable (*__malloc_initialize_hook) __MALLOC_P ((void)) = NULL;
void weak_variable (*__free_hook) __MALLOC_P ((__malloc_ptr_t __ptr,
const __malloc_ptr_t)) = NULL;
__malloc_ptr_t weak_variable (*__malloc_hook)
__MALLOC_P ((size_t __size, const __malloc_ptr_t)) = malloc_hook_ini;
__malloc_ptr_t weak_variable (*__realloc_hook)
__MALLOC_P ((__malloc_ptr_t __ptr, size_t __size, const __malloc_ptr_t))
= realloc_hook_ini;
__malloc_ptr_t weak_variable (*__memalign_hook)
__MALLOC_P ((size_t __alignment, size_t __size, const __malloc_ptr_t))
= memalign_hook_ini;
void weak_variable (*__after_morecore_hook) __MALLOC_P ((void)) = NULL;
/* Whether we are using malloc checking. */
static int using_malloc_checking;
/* A flag that is set by malloc_set_state, to signal that malloc checking
must not be enabled on the request from the user (via the MALLOC_CHECK_
environment variable). It is reset by __malloc_check_init to tell
malloc_set_state that the user has requested malloc checking.
The purpose of this flag is to make sure that malloc checking is not
enabled when the heap to be restored was constructed without malloc
checking, and thus does not contain the required magic bytes.
Otherwise the heap would be corrupted by calls to free and realloc. If
it turns out that the heap was created with malloc checking and the
user has requested it malloc_set_state just calls __malloc_check_init
again to enable it. On the other hand, reusing such a heap without
further malloc checking is safe. */
static int disallow_malloc_check;
/* Activate a standard set of debugging hooks. */
void
__malloc_check_init()
{
if (disallow_malloc_check) {
disallow_malloc_check = 0;
return;
}
using_malloc_checking = 1;
__malloc_hook = malloc_check;
__free_hook = free_check;
__realloc_hook = realloc_check;
__memalign_hook = memalign_check;
if(check_action & 1)
fprintf(stderr, "malloc: using debugging hooks\n");
}
#endif
/* Routines dealing with mmap(). */
#if HAVE_MMAP
#ifndef MAP_ANONYMOUS
static int dev_zero_fd = -1; /* Cached file descriptor for /dev/zero. */
#define MMAP(addr, size, prot, flags) ((dev_zero_fd < 0) ? \
(dev_zero_fd = open("/dev/zero", O_RDWR), \
mmap((addr), (size), (prot), (flags), dev_zero_fd, 0)) : \
mmap((addr), (size), (prot), (flags), dev_zero_fd, 0))
#else
#define MMAP(addr, size, prot, flags) \
(mmap((addr), (size), (prot), (flags)|MAP_ANONYMOUS, -1, 0))
#endif
#if defined __GNUC__ && __GNUC__ >= 2
/* This function is only called from one place, inline it. */
__inline__
#endif
static mchunkptr
internal_function
#if __STD_C
mmap_chunk(size_t size)
#else
mmap_chunk(size) size_t size;
#endif
{
size_t page_mask = malloc_getpagesize - 1;
mchunkptr p;
/* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because
* there is no following chunk whose prev_size field could be used.
*/
size = (size + SIZE_SZ + page_mask) & ~page_mask;
p = (mchunkptr)MMAP(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE);
if(p == (mchunkptr) MAP_FAILED) return 0;
n_mmaps++;
if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps;
/* We demand that eight bytes into a page must be 8-byte aligned. */
assert(aligned_OK(chunk2mem(p)));
/* The offset to the start of the mmapped region is stored
* in the prev_size field of the chunk; normally it is zero,
* but that can be changed in memalign().
*/
p->prev_size = 0;
set_head(p, size|IS_MMAPPED);
mmapped_mem += size;
if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
max_mmapped_mem = mmapped_mem;
#ifdef NO_THREADS
if ((unsigned long)(mmapped_mem + arena_mem + sbrked_mem) > max_total_mem)
max_total_mem = mmapped_mem + arena_mem + sbrked_mem;
#endif
return p;
}
static void
internal_function
#if __STD_C
munmap_chunk(mchunkptr p)
#else
munmap_chunk(p) mchunkptr p;
#endif
{
INTERNAL_SIZE_T size = chunksize(p);
int ret;
assert (chunk_is_mmapped(p));
assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
assert((n_mmaps > 0));
assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0);
n_mmaps--;
mmapped_mem -= (size + p->prev_size);
ret = munmap((char *)p - p->prev_size, size + p->prev_size);
/* munmap returns non-zero on failure */
assert(ret == 0);
}
#if HAVE_MREMAP
static mchunkptr
internal_function
#if __STD_C
mremap_chunk(mchunkptr p, size_t new_size)
#else
mremap_chunk(p, new_size) mchunkptr p; size_t new_size;
#endif
{
size_t page_mask = malloc_getpagesize - 1;
INTERNAL_SIZE_T offset = p->prev_size;
INTERNAL_SIZE_T size = chunksize(p);
char *cp;
assert (chunk_is_mmapped(p));
assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
assert((n_mmaps > 0));
assert(((size + offset) & (malloc_getpagesize-1)) == 0);
/* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask;
cp = (char *)mremap((char *)p - offset, size + offset, new_size,
MREMAP_MAYMOVE);
if (cp == MAP_FAILED) return 0;
p = (mchunkptr)(cp + offset);
assert(aligned_OK(chunk2mem(p)));
assert((p->prev_size == offset));
set_head(p, (new_size - offset)|IS_MMAPPED);
mmapped_mem -= size + offset;
mmapped_mem += new_size;
if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
max_mmapped_mem = mmapped_mem;
#ifdef NO_THREADS
if ((unsigned long)(mmapped_mem + arena_mem + sbrked_mem) > max_total_mem)
max_total_mem = mmapped_mem + arena_mem + sbrked_mem;
#endif
return p;
}
#endif /* HAVE_MREMAP */
#endif /* HAVE_MMAP */
/* Managing heaps and arenas (for concurrent threads) */
#if USE_ARENAS
/* Create a new heap. size is automatically rounded up to a multiple
of the page size. */
static heap_info *
internal_function
#if __STD_C
new_heap(size_t size)
#else
new_heap(size) size_t size;
#endif
{
size_t page_mask = malloc_getpagesize - 1;
char *p1, *p2;
unsigned long ul;
heap_info *h;
if(size+top_pad < HEAP_MIN_SIZE)
size = HEAP_MIN_SIZE;
else if(size+top_pad <= HEAP_MAX_SIZE)
size += top_pad;
else if(size > HEAP_MAX_SIZE)
return 0;
else
size = HEAP_MAX_SIZE;
size = (size + page_mask) & ~page_mask;
/* A memory region aligned to a multiple of HEAP_MAX_SIZE is needed.
No swap space needs to be reserved for the following large
mapping (on Linux, this is the case for all non-writable mappings
anyway). */
p1 = (char *)MMAP(0, HEAP_MAX_SIZE<<1, PROT_NONE, MAP_PRIVATE|MAP_NORESERVE);
if(p1 != MAP_FAILED) {
p2 = (char *)(((unsigned long)p1 + (HEAP_MAX_SIZE-1)) & ~(HEAP_MAX_SIZE-1));
ul = p2 - p1;
if (ul)
munmap(p1, ul);
munmap(p2 + HEAP_MAX_SIZE, HEAP_MAX_SIZE - ul);
} else {
/* Try to take the chance that an allocation of only HEAP_MAX_SIZE
is already aligned. */
p2 = (char *)MMAP(0, HEAP_MAX_SIZE, PROT_NONE, MAP_PRIVATE|MAP_NORESERVE);
if(p2 == MAP_FAILED)
return 0;
if((unsigned long)p2 & (HEAP_MAX_SIZE-1)) {
munmap(p2, HEAP_MAX_SIZE);
return 0;
}
}
if(MMAP(p2, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED)
== (char *) MAP_FAILED) {
munmap(p2, HEAP_MAX_SIZE);
return 0;
}
h = (heap_info *)p2;
h->size = size;
THREAD_STAT(stat_n_heaps++);
return h;
}
/* Grow or shrink a heap. size is automatically rounded up to a
multiple of the page size if it is positive. */
static int
#if __STD_C
grow_heap(heap_info *h, long diff)
#else
grow_heap(h, diff) heap_info *h; long diff;
#endif
{
size_t page_mask = malloc_getpagesize - 1;
long new_size;
if(diff >= 0) {
diff = (diff + page_mask) & ~page_mask;
new_size = (long)h->size + diff;
if(new_size > HEAP_MAX_SIZE)
return -1;
if(MMAP((char *)h + h->size, diff, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED) == (char *) MAP_FAILED)
return -2;
} else {
new_size = (long)h->size + diff;
if(new_size < (long)sizeof(*h))
return -1;
/* Try to re-map the extra heap space freshly to save memory, and
make it inaccessible. */
if((char *)MMAP((char *)h + new_size, -diff, PROT_NONE,
MAP_PRIVATE|MAP_FIXED) == (char *) MAP_FAILED)
return -2;
}
h->size = new_size;
return 0;
}
/* Delete a heap. */
#define delete_heap(heap) munmap((char*)(heap), HEAP_MAX_SIZE)
/* arena_get() acquires an arena and locks the corresponding mutex.
First, try the one last locked successfully by this thread. (This
is the common case and handled with a macro for speed.) Then, loop
once over the circularly linked list of arenas. If no arena is
readily available, create a new one. In this latter case, `size'
is just a hint as to how much memory will be required immediately
in the new arena. */
#define arena_get(ptr, size) do { \
Void_t *vptr = NULL; \
ptr = (arena *)tsd_getspecific(arena_key, vptr); \
if(ptr && !mutex_trylock(&ptr->mutex)) { \
THREAD_STAT(++(ptr->stat_lock_direct)); \
} else \
ptr = arena_get2(ptr, (size)); \
} while(0)
static arena *
internal_function
#if __STD_C
arena_get2(arena *a_tsd, size_t size)
#else
arena_get2(a_tsd, size) arena *a_tsd; size_t size;
#endif
{
arena *a;
heap_info *h;
char *ptr;
int i;
unsigned long misalign;
if(!a_tsd)
a = a_tsd = &main_arena;
else {
a = a_tsd->next;
if(!a) {
/* This can only happen while initializing the new arena. */
(void)mutex_lock(&main_arena.mutex);
THREAD_STAT(++(main_arena.stat_lock_wait));
return &main_arena;
}
}
/* Check the global, circularly linked list for available arenas. */
repeat:
do {
if(!mutex_trylock(&a->mutex)) {
THREAD_STAT(++(a->stat_lock_loop));
tsd_setspecific(arena_key, (Void_t *)a);
return a;
}
a = a->next;
} while(a != a_tsd);
/* If not even the list_lock can be obtained, try again. This can
happen during `atfork', or for example on systems where thread
creation makes it temporarily impossible to obtain _any_
locks. */
if(mutex_trylock(&list_lock)) {
a = a_tsd;
goto repeat;
}
(void)mutex_unlock(&list_lock);
/* Nothing immediately available, so generate a new arena. */
h = new_heap(size + (sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT));
if(!h) {
/* Maybe size is too large to fit in a single heap. So, just try
to create a minimally-sized arena and let chunk_alloc() attempt
to deal with the large request via mmap_chunk(). */
h = new_heap(sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT);
if(!h)
return 0;
}
a = h->ar_ptr = (arena *)(h+1);
for(i=0; i<NAV; i++)
init_bin(a, i);
a->next = NULL;
a->size = h->size;
arena_mem += h->size;
#ifdef NO_THREADS
if((unsigned long)(mmapped_mem + arena_mem + sbrked_mem) > max_total_mem)
max_total_mem = mmapped_mem + arena_mem + sbrked_mem;
#endif
tsd_setspecific(arena_key, (Void_t *)a);
mutex_init(&a->mutex);
i = mutex_lock(&a->mutex); /* remember result */
/* Set up the top chunk, with proper alignment. */
ptr = (char *)(a + 1);
misalign = (unsigned long)chunk2mem(ptr) & MALLOC_ALIGN_MASK;
if (misalign > 0)
ptr += MALLOC_ALIGNMENT - misalign;
top(a) = (mchunkptr)ptr;
set_head(top(a), (((char*)h + h->size) - ptr) | PREV_INUSE);
/* Add the new arena to the list. */
(void)mutex_lock(&list_lock);
a->next = main_arena.next;
main_arena.next = a;
(void)mutex_unlock(&list_lock);
if(i) /* locking failed; keep arena for further attempts later */
return 0;
THREAD_STAT(++(a->stat_lock_loop));
return a;
}
/* find the heap and corresponding arena for a given ptr */
#define heap_for_ptr(ptr) \
((heap_info *)((unsigned long)(ptr) & ~(HEAP_MAX_SIZE-1)))
#define arena_for_ptr(ptr) \
(((mchunkptr)(ptr) < top(&main_arena) && (char *)(ptr) >= sbrk_base) ? \
&main_arena : heap_for_ptr(ptr)->ar_ptr)
#else /* !USE_ARENAS */
/* There is only one arena, main_arena. */
#define arena_get(ptr, sz) (ptr = &main_arena)
#define arena_for_ptr(ptr) (&main_arena)
#endif /* USE_ARENAS */
/*
Debugging support
*/
#if MALLOC_DEBUG
/*
These routines make a number of assertions about the states
of data structures that should be true at all times. If any
are not true, it's very likely that a user program has somehow
trashed memory. (It's also possible that there is a coding error
in malloc. In which case, please report it!)
*/
#if __STD_C
static void do_check_chunk(arena *ar_ptr, mchunkptr p)
#else
static void do_check_chunk(ar_ptr, p) arena *ar_ptr; mchunkptr p;
#endif
{
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
/* No checkable chunk is mmapped */
assert(!chunk_is_mmapped(p));
#if USE_ARENAS
if(ar_ptr != &main_arena) {
heap_info *heap = heap_for_ptr(p);
assert(heap->ar_ptr == ar_ptr);
if(p != top(ar_ptr))
assert((char *)p + sz <= (char *)heap + heap->size);
else
assert((char *)p + sz == (char *)heap + heap->size);
return;
}
#endif
/* Check for legal address ... */
assert((char*)p >= sbrk_base);
if (p != top(ar_ptr))
assert((char*)p + sz <= (char*)top(ar_ptr));
else
assert((char*)p + sz <= sbrk_base + sbrked_mem);
}
#if __STD_C
static void do_check_free_chunk(arena *ar_ptr, mchunkptr p)
#else
static void do_check_free_chunk(ar_ptr, p) arena *ar_ptr; mchunkptr p;
#endif
{
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
mchunkptr next = chunk_at_offset(p, sz);
do_check_chunk(ar_ptr, p);
/* Check whether it claims to be free ... */
assert(!inuse(p));
/* Must have OK size and fields */
assert((long)sz >= (long)MINSIZE);
assert((sz & MALLOC_ALIGN_MASK) == 0);
assert(aligned_OK(chunk2mem(p)));
/* ... matching footer field */
assert(next->prev_size == sz);
/* ... and is fully consolidated */
assert(prev_inuse(p));
assert (next == top(ar_ptr) || inuse(next));
/* ... and has minimally sane links */
assert(p->fd->bk == p);
assert(p->bk->fd == p);
}
#if __STD_C
static void do_check_inuse_chunk(arena *ar_ptr, mchunkptr p)
#else
static void do_check_inuse_chunk(ar_ptr, p) arena *ar_ptr; mchunkptr p;
#endif
{
mchunkptr next = next_chunk(p);
do_check_chunk(ar_ptr, p);
/* Check whether it claims to be in use ... */
assert(inuse(p));
/* ... whether its size is OK (it might be a fencepost) ... */
assert(chunksize(p) >= MINSIZE || next->size == (0|PREV_INUSE));
/* ... and is surrounded by OK chunks.
Since more things can be checked with free chunks than inuse ones,
if an inuse chunk borders them and debug is on, it's worth doing them.
*/
if (!prev_inuse(p))
{
mchunkptr prv = prev_chunk(p);
assert(next_chunk(prv) == p);
do_check_free_chunk(ar_ptr, prv);
}
if (next == top(ar_ptr))
{
assert(prev_inuse(next));
assert(chunksize(next) >= MINSIZE);
}
else if (!inuse(next))
do_check_free_chunk(ar_ptr, next);
}
#if __STD_C
static void do_check_malloced_chunk(arena *ar_ptr,
mchunkptr p, INTERNAL_SIZE_T s)
#else
static void do_check_malloced_chunk(ar_ptr, p, s)
arena *ar_ptr; mchunkptr p; INTERNAL_SIZE_T s;
#endif
{
INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
long room = sz - s;
do_check_inuse_chunk(ar_ptr, p);
/* Legal size ... */
assert((long)sz >= (long)MINSIZE);
assert((sz & MALLOC_ALIGN_MASK) == 0);
assert(room >= 0);
assert(room < (long)MINSIZE);
/* ... and alignment */
assert(aligned_OK(chunk2mem(p)));
/* ... and was allocated at front of an available chunk */
assert(prev_inuse(p));
}
#define check_free_chunk(A,P) do_check_free_chunk(A,P)
#define check_inuse_chunk(A,P) do_check_inuse_chunk(A,P)
#define check_chunk(A,P) do_check_chunk(A,P)
#define check_malloced_chunk(A,P,N) do_check_malloced_chunk(A,P,N)
#else
#define check_free_chunk(A,P)
#define check_inuse_chunk(A,P)
#define check_chunk(A,P)
#define check_malloced_chunk(A,P,N)
#endif
/*
Macro-based internal utilities
*/
/*
Linking chunks in bin lists.
Call these only with variables, not arbitrary expressions, as arguments.
*/
/*
Place chunk p of size s in its bin, in size order,
putting it ahead of others of same size.
*/
#define frontlink(A, P, S, IDX, BK, FD) \
{ \
if (S < MAX_SMALLBIN_SIZE) \
{ \
IDX = smallbin_index(S); \
mark_binblock(A, IDX); \
BK = bin_at(A, IDX); \
FD = BK->fd; \
P->bk = BK; \
P->fd = FD; \
FD->bk = BK->fd = P; \
} \
else \
{ \
IDX = bin_index(S); \
BK = bin_at(A, IDX); \
FD = BK->fd; \
if (FD == BK) mark_binblock(A, IDX); \
else \
{ \
while (FD != BK && S < chunksize(FD)) FD = FD->fd; \
BK = FD->bk; \
} \
P->bk = BK; \
P->fd = FD; \
FD->bk = BK->fd = P; \
} \
}
/* take a chunk off a list */
#define unlink(P, BK, FD) \
{ \
BK = P->bk; \
FD = P->fd; \
FD->bk = BK; \
BK->fd = FD; \
} \
/* Place p as the last remainder */
#define link_last_remainder(A, P) \
{ \
last_remainder(A)->fd = last_remainder(A)->bk = P; \
P->fd = P->bk = last_remainder(A); \
}
/* Clear the last_remainder bin */
#define clear_last_remainder(A) \
(last_remainder(A)->fd = last_remainder(A)->bk = last_remainder(A))
/*
Extend the top-most chunk by obtaining memory from system.
Main interface to sbrk (but see also malloc_trim).
*/
#if defined __GNUC__ && __GNUC__ >= 2
/* This function is called only from one place, inline it. */
__inline__
#endif
static void
internal_function
#if __STD_C
malloc_extend_top(arena *ar_ptr, INTERNAL_SIZE_T nb)
#else
malloc_extend_top(ar_ptr, nb) arena *ar_ptr; INTERNAL_SIZE_T nb;
#endif
{
unsigned long pagesz = malloc_getpagesize;
mchunkptr old_top = top(ar_ptr); /* Record state of old top */
INTERNAL_SIZE_T old_top_size = chunksize(old_top);
INTERNAL_SIZE_T top_size; /* new size of top chunk */
#if USE_ARENAS
if(ar_ptr == &main_arena) {
#endif
char* brk; /* return value from sbrk */
INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */
INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */
char* new_brk; /* return of 2nd sbrk call */
char* old_end = (char*)(chunk_at_offset(old_top, old_top_size));
/* Pad request with top_pad plus minimal overhead */
INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE;
/* If not the first time through, round to preserve page boundary */
/* Otherwise, we need to correct to a page size below anyway. */
/* (We also correct below if an intervening foreign sbrk call.) */
if (sbrk_base != (char*)(-1))
sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1);
brk = (char*)(MORECORE (sbrk_size));
/* Fail if sbrk failed or if a foreign sbrk call killed our space */
if (brk == (char*)(MORECORE_FAILURE) ||
(brk < old_end && old_top != initial_top(&main_arena)))
return;
#if defined _LIBC || defined MALLOC_HOOKS
/* Call the `morecore' hook if necessary. */
if (__after_morecore_hook)
(*__after_morecore_hook) ();
#endif
sbrked_mem += sbrk_size;
if (brk == old_end) { /* can just add bytes to current top */
top_size = sbrk_size + old_top_size;
set_head(old_top, top_size | PREV_INUSE);
old_top = 0; /* don't free below */
} else {
if (sbrk_base == (char*)(-1)) /* First time through. Record base */
sbrk_base = brk;
else
/* Someone else called sbrk(). Count those bytes as sbrked_mem. */
sbrked_mem += brk - (char*)old_end;
/* Guarantee alignment of first new chunk made from this space */
front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK;
if (front_misalign > 0) {
correction = (MALLOC_ALIGNMENT) - front_misalign;
brk += correction;
} else
correction = 0;
/* Guarantee the next brk will be at a page boundary */
correction += pagesz - ((unsigned long)(brk + sbrk_size) & (pagesz - 1));
/* Allocate correction */
new_brk = (char*)(MORECORE (correction));
if (new_brk == (char*)(MORECORE_FAILURE)) return;
#if defined _LIBC || defined MALLOC_HOOKS
/* Call the `morecore' hook if necessary. */
if (__after_morecore_hook)
(*__after_morecore_hook) ();
#endif
sbrked_mem += correction;
top(&main_arena) = chunk_at_offset(brk, 0);
top_size = new_brk - brk + correction;
set_head(top(&main_arena), top_size | PREV_INUSE);
if (old_top == initial_top(&main_arena))
old_top = 0; /* don't free below */
}
if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem)
max_sbrked_mem = sbrked_mem;
#ifdef NO_THREADS
if ((unsigned long)(mmapped_mem + arena_mem + sbrked_mem) > max_total_mem)
max_total_mem = mmapped_mem + arena_mem + sbrked_mem;
#endif
#if USE_ARENAS
} else { /* ar_ptr != &main_arena */
heap_info *old_heap, *heap;
size_t old_heap_size;
if(old_top_size < MINSIZE) /* this should never happen */
return;
/* First try to extend the current heap. */
if(MINSIZE + nb <= old_top_size)
return;
old_heap = heap_for_ptr(old_top);
old_heap_size = old_heap->size;
if(grow_heap(old_heap, MINSIZE + nb - old_top_size) == 0) {
ar_ptr->size += old_heap->size - old_heap_size;
arena_mem += old_heap->size - old_heap_size;
#ifdef NO_THREADS
if(mmapped_mem + arena_mem + sbrked_mem > max_total_mem)
max_total_mem = mmapped_mem + arena_mem + sbrked_mem;
#endif
top_size = ((char *)old_heap + old_heap->size) - (char *)old_top;
set_head(old_top, top_size | PREV_INUSE);
return;
}
/* A new heap must be created. */
heap = new_heap(nb + (MINSIZE + sizeof(*heap)));
if(!heap)
return;
heap->ar_ptr = ar_ptr;
heap->prev = old_heap;
ar_ptr->size += heap->size;
arena_mem += heap->size;
#ifdef NO_THREADS
if((unsigned long)(mmapped_mem + arena_mem + sbrked_mem) > max_total_mem)
max_total_mem = mmapped_mem + arena_mem + sbrked_mem;
#endif
/* Set up the new top, so we can safely use chunk_free() below. */
top(ar_ptr) = chunk_at_offset(heap, sizeof(*heap));
top_size = heap->size - sizeof(*heap);
set_head(top(ar_ptr), top_size | PREV_INUSE);
}
#endif /* USE_ARENAS */
/* We always land on a page boundary */
assert(((unsigned long)((char*)top(ar_ptr) + top_size) & (pagesz-1)) == 0);
/* Setup fencepost and free the old top chunk. */
if(old_top) {
/* The fencepost takes at least MINSIZE bytes, because it might
become the top chunk again later. Note that a footer is set
up, too, although the chunk is marked in use. */
old_top_size -= MINSIZE;
set_head(chunk_at_offset(old_top, old_top_size + 2*SIZE_SZ), 0|PREV_INUSE);
if(old_top_size >= MINSIZE) {
set_head(chunk_at_offset(old_top, old_top_size), (2*SIZE_SZ)|PREV_INUSE);
set_foot(chunk_at_offset(old_top, old_top_size), (2*SIZE_SZ));
set_head_size(old_top, old_top_size);
chunk_free(ar_ptr, old_top);
} else {
set_head(old_top, (old_top_size + 2*SIZE_SZ)|PREV_INUSE);
set_foot(old_top, (old_top_size + 2*SIZE_SZ));
}
}
}
/* Main public routines */
/*
Malloc Algorithm:
The requested size is first converted into a usable form, `nb'.
This currently means to add 4 bytes overhead plus possibly more to
obtain 8-byte alignment and/or to obtain a size of at least
MINSIZE (currently 16, 24, or 32 bytes), the smallest allocatable
size. (All fits are considered `exact' if they are within MINSIZE
bytes.)
From there, the first successful of the following steps is taken:
1. The bin corresponding to the request size is scanned, and if
a chunk of exactly the right size is found, it is taken.
2. The most recently remaindered chunk is used if it is big
enough. This is a form of (roving) first fit, used only in
the absence of exact fits. Runs of consecutive requests use
the remainder of the chunk used for the previous such request
whenever possible. This limited use of a first-fit style
allocation strategy tends to give contiguous chunks
coextensive lifetimes, which improves locality and can reduce
fragmentation in the long run.
3. Other bins are scanned in increasing size order, using a
chunk big enough to fulfill the request, and splitting off
any remainder. This search is strictly by best-fit; i.e.,
the smallest (with ties going to approximately the least
recently used) chunk that fits is selected.
4. If large enough, the chunk bordering the end of memory
(`top') is split off. (This use of `top' is in accord with
the best-fit search rule. In effect, `top' is treated as
larger (and thus less well fitting) than any other available
chunk since it can be extended to be as large as necessary
(up to system limitations).
5. If the request size meets the mmap threshold and the
system supports mmap, and there are few enough currently
allocated mmapped regions, and a call to mmap succeeds,
the request is allocated via direct memory mapping.
6. Otherwise, the top of memory is extended by
obtaining more space from the system (normally using sbrk,
but definable to anything else via the MORECORE macro).
Memory is gathered from the system (in system page-sized
units) in a way that allows chunks obtained across different
sbrk calls to be consolidated, but does not require
contiguous memory. Thus, it should be safe to intersperse
mallocs with other sbrk calls.
All allocations are made from the `lowest' part of any found
chunk. (The implementation invariant is that prev_inuse is
always true of any allocated chunk; i.e., that each allocated
chunk borders either a previously allocated and still in-use chunk,
or the base of its memory arena.)
*/
#if __STD_C
Void_t* mALLOc(size_t bytes)
#else
Void_t* mALLOc(bytes) size_t bytes;
#endif
{
arena *ar_ptr;
INTERNAL_SIZE_T nb; /* padded request size */
mchunkptr victim;
#if defined _LIBC || defined MALLOC_HOOKS
__malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, __const __malloc_ptr_t)) =
__malloc_hook;
if (hook != NULL) {
Void_t* result;
#if defined __GNUC__ && __GNUC__ >= 2
result = (*hook)(bytes, RETURN_ADDRESS (0));
#else
result = (*hook)(bytes, NULL);
#endif
return result;
}
#endif
if(request2size(bytes, nb))
return 0;
arena_get(ar_ptr, nb);
if(!ar_ptr)
return 0;
victim = chunk_alloc(ar_ptr, nb);
if(!victim) {
/* Maybe the failure is due to running out of mmapped areas. */
if(ar_ptr != &main_arena) {
(void)mutex_unlock(&ar_ptr->mutex);
(void)mutex_lock(&main_arena.mutex);
victim = chunk_alloc(&main_arena, nb);
(void)mutex_unlock(&main_arena.mutex);
} else {
#if USE_ARENAS
/* ... or sbrk() has failed and there is still a chance to mmap() */
ar_ptr = arena_get2(ar_ptr->next ? ar_ptr : 0, nb);
(void)mutex_unlock(&main_arena.mutex);
if(ar_ptr) {
victim = chunk_alloc(ar_ptr, nb);
(void)mutex_unlock(&ar_ptr->mutex);
}
#endif
}
if(!victim) return 0;
} else
(void)mutex_unlock(&ar_ptr->mutex);
return BOUNDED_N(chunk2mem(victim), bytes);
}
static mchunkptr
internal_function
#if __STD_C
chunk_alloc(arena *ar_ptr, INTERNAL_SIZE_T nb)
#else
chunk_alloc(ar_ptr, nb) arena *ar_ptr; INTERNAL_SIZE_T nb;
#endif
{
mchunkptr victim; /* inspected/selected chunk */
INTERNAL_SIZE_T victim_size; /* its size */
int idx; /* index for bin traversal */
mbinptr bin; /* associated bin */
mchunkptr remainder; /* remainder from a split */
long remainder_size; /* its size */
int remainder_index; /* its bin index */
unsigned long block; /* block traverser bit */
int startidx; /* first bin of a traversed block */
mchunkptr fwd; /* misc temp for linking */
mchunkptr bck; /* misc temp for linking */
mbinptr q; /* misc temp */
/* Check for exact match in a bin */
if (is_small_request(nb)) /* Faster version for small requests */
{
idx = smallbin_index(nb);
/* No traversal or size check necessary for small bins. */
q = _bin_at(ar_ptr, idx);
victim = last(q);
/* Also scan the next one, since it would have a remainder < MINSIZE */
if (victim == q)
{
q = next_bin(q);
victim = last(q);
}
if (victim != q)
{
victim_size = chunksize(victim);
unlink(victim, bck, fwd);
set_inuse_bit_at_offset(victim, victim_size);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */
}
else
{
idx = bin_index(nb);
bin = bin_at(ar_ptr, idx);
for (victim = last(bin); victim != bin; victim = victim->bk)
{
victim_size = chunksize(victim);
remainder_size = victim_size - nb;
if (remainder_size >= (long)MINSIZE) /* too big */
{
--idx; /* adjust to rescan below after checking last remainder */
break;
}
else if (remainder_size >= 0) /* exact fit */
{
unlink(victim, bck, fwd);
set_inuse_bit_at_offset(victim, victim_size);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
}
++idx;
}
/* Try to use the last split-off remainder */
if ( (victim = last_remainder(ar_ptr)->fd) != last_remainder(ar_ptr))
{
victim_size = chunksize(victim);
remainder_size = victim_size - nb;
if (remainder_size >= (long)MINSIZE) /* re-split */
{
remainder = chunk_at_offset(victim, nb);
set_head(victim, nb | PREV_INUSE);
link_last_remainder(ar_ptr, remainder);
set_head(remainder, remainder_size | PREV_INUSE);
set_foot(remainder, remainder_size);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
clear_last_remainder(ar_ptr);
if (remainder_size >= 0) /* exhaust */
{
set_inuse_bit_at_offset(victim, victim_size);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
/* Else place in bin */
frontlink(ar_ptr, victim, victim_size, remainder_index, bck, fwd);
}
/*
If there are any possibly nonempty big-enough blocks,
search for best fitting chunk by scanning bins in blockwidth units.
*/
if ( (block = idx2binblock(idx)) <= binblocks(ar_ptr))
{
/* Get to the first marked block */
if ( (block & binblocks(ar_ptr)) == 0)
{
/* force to an even block boundary */
idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH;
block <<= 1;
while ((block & binblocks(ar_ptr)) == 0)
{
idx += BINBLOCKWIDTH;
block <<= 1;
}
}
/* For each possibly nonempty block ... */
for (;;)
{
startidx = idx; /* (track incomplete blocks) */
q = bin = _bin_at(ar_ptr, idx);
/* For each bin in this block ... */
do
{
/* Find and use first big enough chunk ... */
for (victim = last(bin); victim != bin; victim = victim->bk)
{
victim_size = chunksize(victim);
remainder_size = victim_size - nb;
if (remainder_size >= (long)MINSIZE) /* split */
{
remainder = chunk_at_offset(victim, nb);
set_head(victim, nb | PREV_INUSE);
unlink(victim, bck, fwd);
link_last_remainder(ar_ptr, remainder);
set_head(remainder, remainder_size | PREV_INUSE);
set_foot(remainder, remainder_size);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
else if (remainder_size >= 0) /* take */
{
set_inuse_bit_at_offset(victim, victim_size);
unlink(victim, bck, fwd);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
}
bin = next_bin(bin);
} while ((++idx & (BINBLOCKWIDTH - 1)) != 0);
/* Clear out the block bit. */
do /* Possibly backtrack to try to clear a partial block */
{
if ((startidx & (BINBLOCKWIDTH - 1)) == 0)
{
binblocks(ar_ptr) &= ~block;
break;
}
--startidx;
q = prev_bin(q);
} while (first(q) == q);
/* Get to the next possibly nonempty block */
if ( (block <<= 1) <= binblocks(ar_ptr) && (block != 0) )
{
while ((block & binblocks(ar_ptr)) == 0)
{
idx += BINBLOCKWIDTH;
block <<= 1;
}
}
else
break;
}
}
/* Try to use top chunk */
/* Require that there be a remainder, ensuring top always exists */
if ( (remainder_size = chunksize(top(ar_ptr)) - nb) < (long)MINSIZE)
{
#if HAVE_MMAP
/* If the request is big and there are not yet too many regions,
and we would otherwise need to extend, try to use mmap instead. */
if ((unsigned long)nb >= (unsigned long)mmap_threshold &&
n_mmaps < n_mmaps_max &&
(victim = mmap_chunk(nb)) != 0)
return victim;
#endif
/* Try to extend */
malloc_extend_top(ar_ptr, nb);
if ((remainder_size = chunksize(top(ar_ptr)) - nb) < (long)MINSIZE)
{
#if HAVE_MMAP
/* A last attempt: when we are out of address space in a
non-main arena, try mmap anyway, as long as it is allowed at
all. */
if (ar_ptr != &main_arena &&
n_mmaps_max > 0 &&
(victim = mmap_chunk(nb)) != 0)
return victim;
#endif
return 0; /* propagate failure */
}
}
victim = top(ar_ptr);
set_head(victim, nb | PREV_INUSE);
top(ar_ptr) = chunk_at_offset(victim, nb);
set_head(top(ar_ptr), remainder_size | PREV_INUSE);
check_malloced_chunk(ar_ptr, victim, nb);
return victim;
}
/*
free() algorithm :
cases:
1. free(0) has no effect.
2. If the chunk was allocated via mmap, it is released via munmap().
3. If a returned chunk borders the current high end of memory,
it is consolidated into the top, and if the total unused
topmost memory exceeds the trim threshold, malloc_trim is
called.
4. Other chunks are consolidated as they arrive, and
placed in corresponding bins. (This includes the case of
consolidating with the current `last_remainder').
*/
#if __STD_C
void fREe(Void_t* mem)
#else
void fREe(mem) Void_t* mem;
#endif
{
arena *ar_ptr;
mchunkptr p; /* chunk corresponding to mem */
#if defined _LIBC || defined MALLOC_HOOKS
void (*hook) __MALLOC_PMT ((__malloc_ptr_t, __const __malloc_ptr_t)) =
__free_hook;
if (hook != NULL) {
#if defined __GNUC__ && __GNUC__ >= 2
(*hook)(mem, RETURN_ADDRESS (0));
#else
(*hook)(mem, NULL);
#endif
return;
}
#endif
if (mem == 0) /* free(0) has no effect */
return;
p = mem2chunk(mem);
#if HAVE_MMAP
if (chunk_is_mmapped(p)) /* release mmapped memory. */
{
munmap_chunk(p);
return;
}
#endif
ar_ptr = arena_for_ptr(p);
#if THREAD_STATS
if(!mutex_trylock(&ar_ptr->mutex))
++(ar_ptr->stat_lock_direct);
else {
(void)mutex_lock(&ar_ptr->mutex);
++(ar_ptr->stat_lock_wait);
}
#else
(void)mutex_lock(&ar_ptr->mutex);
#endif
chunk_free(ar_ptr, p);
(void)mutex_unlock(&ar_ptr->mutex);
}
static void
internal_function
#if __STD_C
chunk_free(arena *ar_ptr, mchunkptr p)
#else
chunk_free(ar_ptr, p) arena *ar_ptr; mchunkptr p;
#endif
{
INTERNAL_SIZE_T hd = p->size; /* its head field */
INTERNAL_SIZE_T sz; /* its size */
int idx; /* its bin index */
mchunkptr next; /* next contiguous chunk */
INTERNAL_SIZE_T nextsz; /* its size */
INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */
mchunkptr bck; /* misc temp for linking */
mchunkptr fwd; /* misc temp for linking */
int islr; /* track whether merging with last_remainder */
check_inuse_chunk(ar_ptr, p);
sz = hd & ~PREV_INUSE;
next = chunk_at_offset(p, sz);
nextsz = chunksize(next);
if (next == top(ar_ptr)) /* merge with top */
{
sz += nextsz;
if (!(hd & PREV_INUSE)) /* consolidate backward */
{
prevsz = p->prev_size;
p = chunk_at_offset(p, -(long)prevsz);
sz += prevsz;
unlink(p, bck, fwd);
}
set_head(p, sz | PREV_INUSE);
top(ar_ptr) = p;
#if USE_ARENAS
if(ar_ptr == &main_arena) {
#endif
if ((unsigned long)(sz) >= (unsigned long)trim_threshold)
main_trim(top_pad);
#if USE_ARENAS
} else {
heap_info *heap = heap_for_ptr(p);
assert(heap->ar_ptr == ar_ptr);
/* Try to get rid of completely empty heaps, if possible. */
if((unsigned long)(sz) >= (unsigned long)trim_threshold ||
p == chunk_at_offset(heap, sizeof(*heap)))
heap_trim(heap, top_pad);
}
#endif
return;
}
islr = 0;
if (!(hd & PREV_INUSE)) /* consolidate backward */
{
prevsz = p->prev_size;
p = chunk_at_offset(p, -(long)prevsz);
sz += prevsz;
if (p->fd == last_remainder(ar_ptr)) /* keep as last_remainder */
islr = 1;
else
unlink(p, bck, fwd);
}
if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */
{
sz += nextsz;
if (!islr && next->fd == last_remainder(ar_ptr))
/* re-insert last_remainder */
{
islr = 1;
link_last_remainder(ar_ptr, p);
}
else
unlink(next, bck, fwd);
next = chunk_at_offset(p, sz);
}
else
set_head(next, nextsz); /* clear inuse bit */
set_head(p, sz | PREV_INUSE);
next->prev_size = sz;
if (!islr)
frontlink(ar_ptr, p, sz, idx, bck, fwd);
#if USE_ARENAS
/* Check whether the heap containing top can go away now. */
if(next->size < MINSIZE &&
(unsigned long)sz > trim_threshold &&
ar_ptr != &main_arena) { /* fencepost */
heap_info *heap = heap_for_ptr(top(ar_ptr));
if(top(ar_ptr) == chunk_at_offset(heap, sizeof(*heap)) &&
heap->prev == heap_for_ptr(p))
heap_trim(heap, top_pad);
}
#endif
}
/*
Realloc algorithm:
Chunks that were obtained via mmap cannot be extended or shrunk
unless HAVE_MREMAP is defined, in which case mremap is used.
Otherwise, if their reallocation is for additional space, they are
copied. If for less, they are just left alone.
Otherwise, if the reallocation is for additional space, and the
chunk can be extended, it is, else a malloc-copy-free sequence is
taken. There are several different ways that a chunk could be
extended. All are tried:
* Extending forward into following adjacent free chunk.
* Shifting backwards, joining preceding adjacent space
* Both shifting backwards and extending forward.
* Extending into newly sbrked space
Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a
size argument of zero (re)allocates a minimum-sized chunk.
If the reallocation is for less space, and the new request is for
a `small' (<512 bytes) size, then the newly unused space is lopped
off and freed.
The old unix realloc convention of allowing the last-free'd chunk
to be used as an argument to realloc is no longer supported.
I don't know of any programs still relying on this feature,
and allowing it would also allow too many other incorrect
usages of realloc to be sensible.
*/
#if __STD_C
Void_t* rEALLOc(Void_t* oldmem, size_t bytes)
#else
Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes;
#endif
{
arena *ar_ptr;
INTERNAL_SIZE_T nb; /* padded request size */
mchunkptr oldp; /* chunk corresponding to oldmem */
INTERNAL_SIZE_T oldsize; /* its size */
mchunkptr newp; /* chunk to return */
#if defined _LIBC || defined MALLOC_HOOKS
__malloc_ptr_t (*hook) __MALLOC_PMT ((__malloc_ptr_t, size_t,
__const __malloc_ptr_t)) =
__realloc_hook;
if (hook != NULL) {
Void_t* result;
#if defined __GNUC__ && __GNUC__ >= 2
result = (*hook)(oldmem, bytes, RETURN_ADDRESS (0));
#else
result = (*hook)(oldmem, bytes, NULL);
#endif
return result;
}
#endif
#ifdef REALLOC_ZERO_BYTES_FREES
if (bytes == 0 && oldmem != NULL) { fREe(oldmem); return 0; }
#endif
/* realloc of null is supposed to be same as malloc */
if (oldmem == 0) return mALLOc(bytes);
oldp = mem2chunk(oldmem);
oldsize = chunksize(oldp);
if(request2size(bytes, nb))
return 0;
#if HAVE_MMAP
if (chunk_is_mmapped(oldp))
{
Void_t* newmem;
#if HAVE_MREMAP
newp = mremap_chunk(oldp, nb);
if(newp)
return BOUNDED_N(chunk2mem(newp), bytes);
#endif
/* Note the extra SIZE_SZ overhead. */
if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */
/* Must alloc, copy, free. */
newmem = mALLOc(bytes);
if (newmem == 0) return 0; /* propagate failure */
MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ, 0);
munmap_chunk(oldp);
return newmem;
}
#endif
ar_ptr = arena_for_ptr(oldp);
#if THREAD_STATS
if(!mutex_trylock(&ar_ptr->mutex))
++(ar_ptr->stat_lock_direct);
else {
(void)mutex_lock(&ar_ptr->mutex);
++(ar_ptr->stat_lock_wait);
}
#else
(void)mutex_lock(&ar_ptr->mutex);
#endif
#ifndef NO_THREADS
/* As in malloc(), remember this arena for the next allocation. */
tsd_setspecific(arena_key, (Void_t *)ar_ptr);
#endif
newp = chunk_realloc(ar_ptr, oldp, oldsize, nb);
(void)mutex_unlock(&ar_ptr->mutex);
return newp ? BOUNDED_N(chunk2mem(newp), bytes) : NULL;
}
static mchunkptr
internal_function
#if __STD_C
chunk_realloc(arena* ar_ptr, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
INTERNAL_SIZE_T nb)
#else
chunk_realloc(ar_ptr, oldp, oldsize, nb)
arena* ar_ptr; mchunkptr oldp; INTERNAL_SIZE_T oldsize, nb;
#endif
{
mchunkptr newp = oldp; /* chunk to return */
INTERNAL_SIZE_T newsize = oldsize; /* its size */
mchunkptr next; /* next contiguous chunk after oldp */
INTERNAL_SIZE_T nextsize; /* its size */
mchunkptr prev; /* previous contiguous chunk before oldp */
INTERNAL_SIZE_T prevsize; /* its size */
mchunkptr remainder; /* holds split off extra space from newp */
INTERNAL_SIZE_T remainder_size; /* its size */
mchunkptr bck; /* misc temp for linking */
mchunkptr fwd; /* misc temp for linking */
check_inuse_chunk(ar_ptr, oldp);
if ((long)(oldsize) < (long)(nb))
{
Void_t* oldmem = BOUNDED_N(chunk2mem(oldp), oldsize);
/* Try expanding forward */
next = chunk_at_offset(oldp, oldsize);
if (next == top(ar_ptr) || !inuse(next))
{
nextsize = chunksize(next);
/* Forward into top only if a remainder */
if (next == top(ar_ptr))
{
if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE))
{
newsize += nextsize;
top(ar_ptr) = chunk_at_offset(oldp, nb);
set_head(top(ar_ptr), (newsize - nb) | PREV_INUSE);
set_head_size(oldp, nb);
return oldp;
}
}
/* Forward into next chunk */
else if (((long)(nextsize + newsize) >= (long)(nb)))
{
unlink(next, bck, fwd);
newsize += nextsize;
goto split;
}
}
else
{
next = 0;
nextsize = 0;
}
oldsize -= SIZE_SZ;
/* Try shifting backwards. */
if (!prev_inuse(oldp))
{
prev = prev_chunk(oldp);
prevsize = chunksize(prev);
/* try forward + backward first to save a later consolidation */
if (next != 0)
{
/* into top */
if (next == top(ar_ptr))
{
if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE))
{
unlink(prev, bck, fwd);
newp = prev;
newsize += prevsize + nextsize;
MALLOC_COPY(BOUNDED_N(chunk2mem(newp), oldsize), oldmem, oldsize,
1);
top(ar_ptr) = chunk_at_offset(newp, nb);
set_head(top(ar_ptr), (newsize - nb) | PREV_INUSE);
set_head_size(newp, nb);
return newp;
}
}
/* into next chunk */
else if (((long)(nextsize + prevsize + newsize) >= (long)(nb)))
{
unlink(next, bck, fwd);
unlink(prev, bck, fwd);
newp = prev;
newsize += nextsize + prevsize;
MALLOC_COPY(BOUNDED_N(chunk2mem(newp), oldsize), oldmem, oldsize, 1);
goto split;
}
}
/* backward only */
if (prev != 0 && (long)(prevsize + newsize) >= (long)nb)
{
unlink(prev, bck, fwd);
newp = prev;
newsize += prevsize;
MALLOC_COPY(BOUNDED_N(chunk2mem(newp), oldsize), oldmem, oldsize, 1);
goto split;
}
}
/* Must allocate */
newp = chunk_alloc (ar_ptr, nb);
if (newp == 0) {
/* Maybe the failure is due to running out of mmapped areas. */
if (ar_ptr != &main_arena) {
(void)mutex_lock(&main_arena.mutex);
newp = chunk_alloc(&main_arena, nb);
(void)mutex_unlock(&main_arena.mutex);
} else {
#if USE_ARENAS
/* ... or sbrk() has failed and there is still a chance to mmap() */
arena* ar_ptr2 = arena_get2(ar_ptr->next ? ar_ptr : 0, nb);
if(ar_ptr2) {
newp = chunk_alloc(ar_ptr2, nb);
(void)mutex_unlock(&ar_ptr2->mutex);
}
#endif
}
if (newp == 0) /* propagate failure */
return 0;
}
/* Avoid copy if newp is next chunk after oldp. */
/* (This can only happen when new chunk is sbrk'ed.) */
if ( newp == next_chunk(oldp))
{
newsize += chunksize(newp);
newp = oldp;
goto split;
}
/* Otherwise copy, free, and exit */
MALLOC_COPY(BOUNDED_N(chunk2mem(newp), oldsize), oldmem, oldsize, 0);
chunk_free(ar_ptr, oldp);
return newp;
}
split: /* split off extra room in old or expanded chunk */
if (newsize - nb >= MINSIZE) /* split off remainder */
{
remainder = chunk_at_offset(newp, nb);
remainder_size = newsize - nb;
set_head_size(newp, nb);
set_head(remainder, remainder_size | PREV_INUSE);
set_inuse_bit_at_offset(remainder, remainder_size);
chunk_free(ar_ptr, remainder);
}
else
{
set_head_size(newp, newsize);
set_inuse_bit_at_offset(newp, newsize);
}
check_inuse_chunk(ar_ptr, newp);
return newp;
}
/*
memalign algorithm:
memalign requests more than enough space from malloc, finds a spot
within that chunk that meets the alignment request, and then
possibly frees the leading and trailing space.
The alignment argument must be a power of two. This property is not
checked by memalign, so misuse may result in random runtime errors.
8-byte alignment is guaranteed by normal malloc calls, so don't
bother calling memalign with an argument of 8 or less.
Overreliance on memalign is a sure way to fragment space.
*/
#if __STD_C
Void_t* mEMALIGn(size_t alignment, size_t bytes)
#else
Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes;
#endif
{
arena *ar_ptr;
INTERNAL_SIZE_T nb; /* padded request size */
mchunkptr p;
#if defined _LIBC || defined MALLOC_HOOKS
__malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, size_t,
__const __malloc_ptr_t)) =
__memalign_hook;
if (hook != NULL) {
Void_t* result;
#if defined __GNUC__ && __GNUC__ >= 2
result = (*hook)(alignment, bytes, RETURN_ADDRESS (0));
#else
result = (*hook)(alignment, bytes, NULL);
#endif
return result;
}
#endif
/* If need less alignment than we give anyway, just relay to malloc */
if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes);
/* Otherwise, ensure that it is at least a minimum chunk size */
if (alignment < MINSIZE) alignment = MINSIZE;
if(request2size(bytes, nb))
return 0;
arena_get(ar_ptr, nb + alignment + MINSIZE);
if(!ar_ptr)
return 0;
p = chunk_align(ar_ptr, nb, alignment);
(void)mutex_unlock(&ar_ptr->mutex);
if(!p) {
/* Maybe the failure is due to running out of mmapped areas. */
if(ar_ptr != &main_arena) {
(void)mutex_lock(&main_arena.mutex);
p = chunk_align(&main_arena, nb, alignment);
(void)mutex_unlock(&main_arena.mutex);
} else {
#if USE_ARENAS
/* ... or sbrk() has failed and there is still a chance to mmap() */
ar_ptr = arena_get2(ar_ptr->next ? ar_ptr : 0, nb);
if(ar_ptr) {
p = chunk_align(ar_ptr, nb, alignment);
(void)mutex_unlock(&ar_ptr->mutex);
}
#endif
}
if(!p) return 0;
}
return BOUNDED_N(chunk2mem(p), bytes);
}
static mchunkptr
internal_function
#if __STD_C
chunk_align(arena* ar_ptr, INTERNAL_SIZE_T nb, size_t alignment)
#else
chunk_align(ar_ptr, nb, alignment)
arena* ar_ptr; INTERNAL_SIZE_T nb; size_t alignment;
#endif
{
unsigned long m; /* memory returned by malloc call */
mchunkptr p; /* corresponding chunk */
char* brk; /* alignment point within p */
mchunkptr newp; /* chunk to return */
INTERNAL_SIZE_T newsize; /* its size */
INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */
mchunkptr remainder; /* spare room at end to split off */
long remainder_size; /* its size */
/* Call chunk_alloc with worst case padding to hit alignment. */
p = chunk_alloc(ar_ptr, nb + alignment + MINSIZE);
if (p == 0)
return 0; /* propagate failure */
m = (unsigned long)chunk2mem(p);
if ((m % alignment) == 0) /* aligned */
{
#if HAVE_MMAP
if(chunk_is_mmapped(p)) {
return p; /* nothing more to do */
}
#endif
}
else /* misaligned */
{
/*
Find an aligned spot inside chunk.
Since we need to give back leading space in a chunk of at
least MINSIZE, if the first calculation places us at
a spot with less than MINSIZE leader, we can move to the
next aligned spot -- we've allocated enough total room so that
this is always possible.
*/
brk = (char*)mem2chunk(((m + alignment - 1)) & -(long)alignment);
if ((long)(brk - (char*)(p)) < (long)MINSIZE) brk += alignment;
newp = chunk_at_offset(brk, 0);
leadsize = brk - (char*)(p);
newsize = chunksize(p) - leadsize;
#if HAVE_MMAP
if(chunk_is_mmapped(p))
{
newp->prev_size = p->prev_size + leadsize;
set_head(newp, newsize|IS_MMAPPED);
return newp;
}
#endif
/* give back leader, use the rest */
set_head(newp, newsize | PREV_INUSE);
set_inuse_bit_at_offset(newp, newsize);
set_head_size(p, leadsize);
chunk_free(ar_ptr, p);
p = newp;
assert (newsize>=nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0);
}
/* Also give back spare room at the end */
remainder_size = chunksize(p) - nb;
if (remainder_size >= (long)MINSIZE)
{
remainder = chunk_at_offset(p, nb);
set_head(remainder, remainder_size | PREV_INUSE);
set_head_size(p, nb);
chunk_free(ar_ptr, remainder);
}
check_inuse_chunk(ar_ptr, p);
return p;
}
/*
valloc just invokes memalign with alignment argument equal
to the page size of the system (or as near to this as can
be figured out from all the includes/defines above.)
*/
#if __STD_C
Void_t* vALLOc(size_t bytes)
#else
Void_t* vALLOc(bytes) size_t bytes;
#endif
{
if(__malloc_initialized < 0)
ptmalloc_init ();
return mEMALIGn (malloc_getpagesize, bytes);
}
/*
pvalloc just invokes valloc for the nearest pagesize
that will accommodate request
*/
#if __STD_C
Void_t* pvALLOc(size_t bytes)
#else
Void_t* pvALLOc(bytes) size_t bytes;
#endif
{
size_t pagesize;
if(__malloc_initialized < 0)
ptmalloc_init ();
pagesize = malloc_getpagesize;
return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1));
}
/*
calloc calls chunk_alloc, then zeroes out the allocated chunk.
*/
#if __STD_C
Void_t* cALLOc(size_t n, size_t elem_size)
#else
Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size;
#endif
{
arena *ar_ptr;
mchunkptr p, oldtop;
INTERNAL_SIZE_T sz, csz, oldtopsize;
Void_t* mem;
#if defined _LIBC || defined MALLOC_HOOKS
__malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, __const __malloc_ptr_t)) =
__malloc_hook;
if (hook != NULL) {
sz = n * elem_size;
#if defined __GNUC__ && __GNUC__ >= 2
mem = (*hook)(sz, RETURN_ADDRESS (0));
#else
mem = (*hook)(sz, NULL);
#endif
if(mem == 0)
return 0;
#ifdef HAVE_MEMSET
return memset(mem, 0, sz);
#else
while(sz > 0) ((char*)mem)[--sz] = 0; /* rather inefficient */
return mem;
#endif
}
#endif
if(request2size(n * elem_size, sz))
return 0;
arena_get(ar_ptr, sz);
if(!ar_ptr)
return 0;
/* Check if expand_top called, in which case there may be
no need to clear. */
#if MORECORE_CLEARS
oldtop = top(ar_ptr);
oldtopsize = chunksize(top(ar_ptr));
#if MORECORE_CLEARS < 2
/* Only newly allocated memory is guaranteed to be cleared. */
if (ar_ptr == &main_arena &&
oldtopsize < sbrk_base + max_sbrked_mem - (char *)oldtop)
oldtopsize = (sbrk_base + max_sbrked_mem - (char *)oldtop);
#endif
#endif
p = chunk_alloc (ar_ptr, sz);
/* Only clearing follows, so we can unlock early. */
(void)mutex_unlock(&ar_ptr->mutex);
if (p == 0) {
/* Maybe the failure is due to running out of mmapped areas. */
if(ar_ptr != &main_arena) {
(void)mutex_lock(&main_arena.mutex);
p = chunk_alloc(&main_arena, sz);
(void)mutex_unlock(&main_arena.mutex);
} else {
#if USE_ARENAS
/* ... or sbrk() has failed and there is still a chance to mmap() */
(void)mutex_lock(&main_arena.mutex);
ar_ptr = arena_get2(ar_ptr->next ? ar_ptr : 0, sz);
(void)mutex_unlock(&main_arena.mutex);
if(ar_ptr) {
p = chunk_alloc(ar_ptr, sz);
(void)mutex_unlock(&ar_ptr->mutex);
}
#endif
}
if (p == 0) return 0;
}
mem = BOUNDED_N(chunk2mem(p), n * elem_size);
/* Two optional cases in which clearing not necessary */
#if HAVE_MMAP
if (chunk_is_mmapped(p)) return mem;
#endif
csz = chunksize(p);
#if MORECORE_CLEARS
if (p == oldtop && csz > oldtopsize) {
/* clear only the bytes from non-freshly-sbrked memory */
csz = oldtopsize;
}
#endif
csz -= SIZE_SZ;
MALLOC_ZERO(BOUNDED_N(chunk2mem(p), csz), csz);
return mem;
}
/*
cfree just calls free. It is needed/defined on some systems
that pair it with calloc, presumably for odd historical reasons.
*/
#if !defined(_LIBC)
#if __STD_C
void cfree(Void_t *mem)
#else
void cfree(mem) Void_t *mem;
#endif
{
fREe(mem);
}
#endif
/*
Malloc_trim gives memory back to the system (via negative
arguments to sbrk) if there is unused memory at the `high' end of
the malloc pool. You can call this after freeing large blocks of
memory to potentially reduce the system-level memory requirements
of a program. However, it cannot guarantee to reduce memory. Under
some allocation patterns, some large free blocks of memory will be
locked between two used chunks, so they cannot be given back to
the system.
The `pad' argument to malloc_trim represents the amount of free
trailing space to leave untrimmed. If this argument is zero,
only the minimum amount of memory to maintain internal data
structures will be left (one page or less). Non-zero arguments
can be supplied to maintain enough trailing space to service
future expected allocations without having to re-obtain memory
from the system.
Malloc_trim returns 1 if it actually released any memory, else 0.
*/
#if __STD_C
int mALLOC_TRIm(size_t pad)
#else
int mALLOC_TRIm(pad) size_t pad;
#endif
{
int res;
(void)mutex_lock(&main_arena.mutex);
res = main_trim(pad);
(void)mutex_unlock(&main_arena.mutex);
return res;
}
/* Trim the main arena. */
static int
internal_function
#if __STD_C
main_trim(size_t pad)
#else
main_trim(pad) size_t pad;
#endif
{
mchunkptr top_chunk; /* The current top chunk */
long top_size; /* Amount of top-most memory */
long extra; /* Amount to release */
char* current_brk; /* address returned by pre-check sbrk call */
char* new_brk; /* address returned by negative sbrk call */
unsigned long pagesz = malloc_getpagesize;
top_chunk = top(&main_arena);
top_size = chunksize(top_chunk);
extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz;
if (extra < (long)pagesz) /* Not enough memory to release */
return 0;
/* Test to make sure no one else called sbrk */
current_brk = (char*)(MORECORE (0));
if (current_brk != (char*)(top_chunk) + top_size)
return 0; /* Apparently we don't own memory; must fail */
new_brk = (char*)(MORECORE (-extra));
#if defined _LIBC || defined MALLOC_HOOKS
/* Call the `morecore' hook if necessary. */
if (__after_morecore_hook)
(*__after_morecore_hook) ();
#endif
if (new_brk == (char*)(MORECORE_FAILURE)) { /* sbrk failed? */
/* Try to figure out what we have */
current_brk = (char*)(MORECORE (0));
top_size = current_brk - (char*)top_chunk;
if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */
{
sbrked_mem = current_brk - sbrk_base;
set_head(top_chunk, top_size | PREV_INUSE);
}
check_chunk(&main_arena, top_chunk);
return 0;
}
sbrked_mem -= extra;
/* Success. Adjust top accordingly. */
set_head(top_chunk, (top_size - extra) | PREV_INUSE);
check_chunk(&main_arena, top_chunk);
return 1;
}
#if USE_ARENAS
static int
internal_function
#if __STD_C
heap_trim(heap_info *heap, size_t pad)
#else
heap_trim(heap, pad) heap_info *heap; size_t pad;
#endif
{
unsigned long pagesz = malloc_getpagesize;
arena *ar_ptr = heap->ar_ptr;
mchunkptr top_chunk = top(ar_ptr), p, bck, fwd;
heap_info *prev_heap;
long new_size, top_size, extra;
/* Can this heap go away completely ? */
while(top_chunk == chunk_at_offset(heap, sizeof(*heap))) {
prev_heap = heap->prev;
p = chunk_at_offset(prev_heap, prev_heap->size - (MINSIZE-2*SIZE_SZ));
assert(p->size == (0|PREV_INUSE)); /* must be fencepost */
p = prev_chunk(p);
new_size = chunksize(p) + (MINSIZE-2*SIZE_SZ);
assert(new_size>0 && new_size<(long)(2*MINSIZE));
if(!prev_inuse(p))
new_size += p->prev_size;
assert(new_size>0 && new_size<HEAP_MAX_SIZE);
if(new_size + (HEAP_MAX_SIZE - prev_heap->size) < pad + MINSIZE + pagesz)
break;
ar_ptr->size -= heap->size;
arena_mem -= heap->size;
delete_heap(heap);
heap = prev_heap;
if(!prev_inuse(p)) { /* consolidate backward */
p = prev_chunk(p);
unlink(p, bck, fwd);
}
assert(((unsigned long)((char*)p + new_size) & (pagesz-1)) == 0);
assert( ((char*)p + new_size) == ((char*)heap + heap->size) );
top(ar_ptr) = top_chunk = p;
set_head(top_chunk, new_size | PREV_INUSE);
check_chunk(ar_ptr, top_chunk);
}
top_size = chunksize(top_chunk);
extra = ((top_size - pad - MINSIZE + (pagesz-1))/pagesz - 1) * pagesz;
if(extra < (long)pagesz)
return 0;
/* Try to shrink. */
if(grow_heap(heap, -extra) != 0)
return 0;
ar_ptr->size -= extra;
arena_mem -= extra;
/* Success. Adjust top accordingly. */
set_head(top_chunk, (top_size - extra) | PREV_INUSE);
check_chunk(ar_ptr, top_chunk);
return 1;
}
#endif /* USE_ARENAS */
/*
malloc_usable_size:
This routine tells you how many bytes you can actually use in an
allocated chunk, which may be more than you requested (although
often not). You can use this many bytes without worrying about
overwriting other allocated objects. Not a particularly great
programming practice, but still sometimes useful.
*/
#if __STD_C
size_t mALLOC_USABLE_SIZe(Void_t* mem)
#else
size_t mALLOC_USABLE_SIZe(mem) Void_t* mem;
#endif
{
mchunkptr p;
if (mem == 0)
return 0;
else
{
p = mem2chunk(mem);
if(!chunk_is_mmapped(p))
{
if (!inuse(p)) return 0;
check_inuse_chunk(arena_for_ptr(mem), p);
return chunksize(p) - SIZE_SZ;
}
return chunksize(p) - 2*SIZE_SZ;
}
}
/* Utility to update mallinfo for malloc_stats() and mallinfo() */
static void
#if __STD_C
malloc_update_mallinfo(arena *ar_ptr, struct mallinfo *mi)
#else
malloc_update_mallinfo(ar_ptr, mi) arena *ar_ptr; struct mallinfo *mi;
#endif
{
int i, navail;
mbinptr b;
mchunkptr p;
#if MALLOC_DEBUG
mchunkptr q;
#endif
INTERNAL_SIZE_T avail;
(void)mutex_lock(&ar_ptr->mutex);
avail = chunksize(top(ar_ptr));
navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0;
for (i = 1; i < NAV; ++i)
{
b = bin_at(ar_ptr, i);
for (p = last(b); p != b; p = p->bk)
{
#if MALLOC_DEBUG
check_free_chunk(ar_ptr, p);
for (q = next_chunk(p);
q != top(ar_ptr) && inuse(q) && (long)chunksize(q) > 0;
q = next_chunk(q))
check_inuse_chunk(ar_ptr, q);
#endif
avail += chunksize(p);
navail++;
}
}
mi->arena = ar_ptr->size;
mi->ordblks = navail;
mi->smblks = mi->usmblks = mi->fsmblks = 0; /* clear unused fields */
mi->uordblks = ar_ptr->size - avail;
mi->fordblks = avail;
mi->hblks = n_mmaps;
mi->hblkhd = mmapped_mem;
mi->keepcost = chunksize(top(ar_ptr));
(void)mutex_unlock(&ar_ptr->mutex);
}
#if USE_ARENAS && MALLOC_DEBUG > 1
/* Print the complete contents of a single heap to stderr. */
static void
#if __STD_C
dump_heap(heap_info *heap)
#else
dump_heap(heap) heap_info *heap;
#endif
{
char *ptr;
mchunkptr p;
fprintf(stderr, "Heap %p, size %10lx:\n", heap, (long)heap->size);
ptr = (heap->ar_ptr != (arena*)(heap+1)) ?
(char*)(heap + 1) : (char*)(heap + 1) + sizeof(arena);
p = (mchunkptr)(((unsigned long)ptr + MALLOC_ALIGN_MASK) &
~MALLOC_ALIGN_MASK);
for(;;) {
fprintf(stderr, "chunk %p size %10lx", p, (long)p->size);
if(p == top(heap->ar_ptr)) {
fprintf(stderr, " (top)\n");
break;
} else if(p->size == (0|PREV_INUSE)) {
fprintf(stderr, " (fence)\n");
break;
}
fprintf(stderr, "\n");
p = next_chunk(p);
}
}
#endif
/*
malloc_stats:
For all arenas separately and in total, prints on stderr the
amount of space obtained from the system, and the current number
of bytes allocated via malloc (or realloc, etc) but not yet
freed. (Note that this is the number of bytes allocated, not the
number requested. It will be larger than the number requested
because of alignment and bookkeeping overhead.) When not compiled
for multiple threads, the maximum amount of allocated memory
(which may be more than current if malloc_trim and/or munmap got
called) is also reported. When using mmap(), prints the maximum
number of simultaneous mmap regions used, too.
*/
void mALLOC_STATs()
{
int i;
arena *ar_ptr;
struct mallinfo mi;
unsigned int in_use_b = mmapped_mem, system_b = in_use_b;
#if THREAD_STATS
long stat_lock_direct = 0, stat_lock_loop = 0, stat_lock_wait = 0;
#endif
for(i=0, ar_ptr = &main_arena;; i++) {
malloc_update_mallinfo(ar_ptr, &mi);
fprintf(stderr, "Arena %d:\n", i);
fprintf(stderr, "system bytes = %10u\n", (unsigned int)mi.arena);
fprintf(stderr, "in use bytes = %10u\n", (unsigned int)mi.uordblks);
system_b += mi.arena;
in_use_b += mi.uordblks;
#if THREAD_STATS
stat_lock_direct += ar_ptr->stat_lock_direct;
stat_lock_loop += ar_ptr->stat_lock_loop;
stat_lock_wait += ar_ptr->stat_lock_wait;
#endif
#if USE_ARENAS && MALLOC_DEBUG > 1
if(ar_ptr != &main_arena) {
heap_info *heap;
(void)mutex_lock(&ar_ptr->mutex);
heap = heap_for_ptr(top(ar_ptr));
while(heap) { dump_heap(heap); heap = heap->prev; }
(void)mutex_unlock(&ar_ptr->mutex);
}
#endif
ar_ptr = ar_ptr->next;
if(ar_ptr == &main_arena) break;
}
#if HAVE_MMAP
fprintf(stderr, "Total (incl. mmap):\n");
#else
fprintf(stderr, "Total:\n");
#endif
fprintf(stderr, "system bytes = %10u\n", system_b);
fprintf(stderr, "in use bytes = %10u\n", in_use_b);
#ifdef NO_THREADS
fprintf(stderr, "max system bytes = %10u\n", (unsigned int)max_total_mem);
#endif
#if HAVE_MMAP
fprintf(stderr, "max mmap regions = %10u\n", (unsigned int)max_n_mmaps);
fprintf(stderr, "max mmap bytes = %10lu\n", max_mmapped_mem);
#endif
#if THREAD_STATS
fprintf(stderr, "heaps created = %10d\n", stat_n_heaps);
fprintf(stderr, "locked directly = %10ld\n", stat_lock_direct);
fprintf(stderr, "locked in loop = %10ld\n", stat_lock_loop);
fprintf(stderr, "locked waiting = %10ld\n", stat_lock_wait);
fprintf(stderr, "locked total = %10ld\n",
stat_lock_direct + stat_lock_loop + stat_lock_wait);
#endif
}
/*
mallinfo returns a copy of updated current mallinfo.
The information reported is for the arena last used by the thread.
*/
struct mallinfo mALLINFo()
{
struct mallinfo mi;
Void_t *vptr = NULL;
#ifndef NO_THREADS
tsd_getspecific(arena_key, vptr);
if(vptr == ATFORK_ARENA_PTR)
vptr = (Void_t*)&main_arena;
#endif
malloc_update_mallinfo((vptr ? (arena*)vptr : &main_arena), &mi);
return mi;
}
/*
mallopt:
mallopt is the general SVID/XPG interface to tunable parameters.
The format is to provide a (parameter-number, parameter-value) pair.
mallopt then sets the corresponding parameter to the argument
value if it can (i.e., so long as the value is meaningful),
and returns 1 if successful else 0.
See descriptions of tunable parameters above.
*/
#if __STD_C
int mALLOPt(int param_number, int value)
#else
int mALLOPt(param_number, value) int param_number; int value;
#endif
{
switch(param_number)
{
case M_TRIM_THRESHOLD:
trim_threshold = value; return 1;
case M_TOP_PAD:
top_pad = value; return 1;
case M_MMAP_THRESHOLD:
#if USE_ARENAS
/* Forbid setting the threshold too high. */
if((unsigned long)value > HEAP_MAX_SIZE/2) return 0;
#endif
mmap_threshold = value; return 1;
case M_MMAP_MAX:
#if HAVE_MMAP
n_mmaps_max = value; return 1;
#else
if (value != 0) return 0; else n_mmaps_max = value; return 1;
#endif
case M_CHECK_ACTION:
check_action = value; return 1;
default:
return 0;
}
}
/* Get/set state: malloc_get_state() records the current state of all
malloc variables (_except_ for the actual heap contents and `hook'
function pointers) in a system dependent, opaque data structure.
This data structure is dynamically allocated and can be free()d
after use. malloc_set_state() restores the state of all malloc
variables to the previously obtained state. This is especially
useful when using this malloc as part of a shared library, and when
the heap contents are saved/restored via some other method. The
primary example for this is GNU Emacs with its `dumping' procedure.
`Hook' function pointers are never saved or restored by these
functions, with two exceptions: If malloc checking was in use when
malloc_get_state() was called, then malloc_set_state() calls
__malloc_check_init() if possible; if malloc checking was not in
use in the recorded state but the user requested malloc checking,
then the hooks are reset to 0. */
#define MALLOC_STATE_MAGIC 0x444c4541l
#define MALLOC_STATE_VERSION (0*0x100l + 1l) /* major*0x100 + minor */
struct malloc_state {
long magic;
long version;
mbinptr av[NAV * 2 + 2];
char* sbrk_base;
int sbrked_mem_bytes;
unsigned long trim_threshold;
unsigned long top_pad;
unsigned int n_mmaps_max;
unsigned long mmap_threshold;
int check_action;
unsigned long max_sbrked_mem;
unsigned long max_total_mem;
unsigned int n_mmaps;
unsigned int max_n_mmaps;
unsigned long mmapped_mem;
unsigned long max_mmapped_mem;
int using_malloc_checking;
};
Void_t*
mALLOC_GET_STATe()
{
struct malloc_state* ms;
int i;
mbinptr b;
ms = (struct malloc_state*)mALLOc(sizeof(*ms));
if (!ms)
return 0;
(void)mutex_lock(&main_arena.mutex);
ms->magic = MALLOC_STATE_MAGIC;
ms->version = MALLOC_STATE_VERSION;
ms->av[0] = main_arena.av[0];
ms->av[1] = main_arena.av[1];
for(i=0; i<NAV; i++) {
b = bin_at(&main_arena, i);
if(first(b) == b)
ms->av[2*i+2] = ms->av[2*i+3] = 0; /* empty bin (or initial top) */
else {
ms->av[2*i+2] = first(b);
ms->av[2*i+3] = last(b);
}
}
ms->sbrk_base = sbrk_base;
ms->sbrked_mem_bytes = sbrked_mem;
ms->trim_threshold = trim_threshold;
ms->top_pad = top_pad;
ms->n_mmaps_max = n_mmaps_max;
ms->mmap_threshold = mmap_threshold;
ms->check_action = check_action;
ms->max_sbrked_mem = max_sbrked_mem;
#ifdef NO_THREADS
ms->max_total_mem = max_total_mem;
#else
ms->max_total_mem = 0;
#endif
ms->n_mmaps = n_mmaps;
ms->max_n_mmaps = max_n_mmaps;
ms->mmapped_mem = mmapped_mem;
ms->max_mmapped_mem = max_mmapped_mem;
#if defined _LIBC || defined MALLOC_HOOKS
ms->using_malloc_checking = using_malloc_checking;
#else
ms->using_malloc_checking = 0;
#endif
(void)mutex_unlock(&main_arena.mutex);
return (Void_t*)ms;
}
int
#if __STD_C
mALLOC_SET_STATe(Void_t* msptr)
#else
mALLOC_SET_STATe(msptr) Void_t* msptr;
#endif
{
struct malloc_state* ms = (struct malloc_state*)msptr;
int i;
mbinptr b;
#if defined _LIBC || defined MALLOC_HOOKS
disallow_malloc_check = 1;
#endif
ptmalloc_init();
if(ms->magic != MALLOC_STATE_MAGIC) return -1;
/* Must fail if the major version is too high. */
if((ms->version & ~0xffl) > (MALLOC_STATE_VERSION & ~0xffl)) return -2;
(void)mutex_lock(&main_arena.mutex);
main_arena.av[0] = ms->av[0];
main_arena.av[1] = ms->av[1];
for(i=0; i<NAV; i++) {
b = bin_at(&main_arena, i);
if(ms->av[2*i+2] == 0)
first(b) = last(b) = b;
else {
first(b) = ms->av[2*i+2];
last(b) = ms->av[2*i+3];
if(i > 0) {
/* Make sure the links to the `av'-bins in the heap are correct. */
first(b)->bk = b;
last(b)->fd = b;
}
}
}
sbrk_base = ms->sbrk_base;
sbrked_mem = ms->sbrked_mem_bytes;
trim_threshold = ms->trim_threshold;
top_pad = ms->top_pad;
n_mmaps_max = ms->n_mmaps_max;
mmap_threshold = ms->mmap_threshold;
check_action = ms->check_action;
max_sbrked_mem = ms->max_sbrked_mem;
#ifdef NO_THREADS
max_total_mem = ms->max_total_mem;
#endif
n_mmaps = ms->n_mmaps;
max_n_mmaps = ms->max_n_mmaps;
mmapped_mem = ms->mmapped_mem;
max_mmapped_mem = ms->max_mmapped_mem;
/* add version-dependent code here */
if (ms->version >= 1) {
#if defined _LIBC || defined MALLOC_HOOKS
/* Check whether it is safe to enable malloc checking, or whether
it is necessary to disable it. */
if (ms->using_malloc_checking && !using_malloc_checking &&
!disallow_malloc_check)
__malloc_check_init ();
else if (!ms->using_malloc_checking && using_malloc_checking) {
__malloc_hook = 0;
__free_hook = 0;
__realloc_hook = 0;
__memalign_hook = 0;
using_malloc_checking = 0;
}
#endif
}
(void)mutex_unlock(&main_arena.mutex);
return 0;
}
#if defined _LIBC || defined MALLOC_HOOKS
/* A simple, standard set of debugging hooks. Overhead is `only' one
byte per chunk; still this will catch most cases of double frees or
overruns. The goal here is to avoid obscure crashes due to invalid
usage, unlike in the MALLOC_DEBUG code. */
#define MAGICBYTE(p) ( ( ((size_t)p >> 3) ^ ((size_t)p >> 11)) & 0xFF )
/* Instrument a chunk with overrun detector byte(s) and convert it
into a user pointer with requested size sz. */
static Void_t*
internal_function
#if __STD_C
chunk2mem_check(mchunkptr p, size_t sz)
#else
chunk2mem_check(p, sz) mchunkptr p; size_t sz;
#endif
{
unsigned char* m_ptr = (unsigned char*)BOUNDED_N(chunk2mem(p), sz);
size_t i;
for(i = chunksize(p) - (chunk_is_mmapped(p) ? 2*SIZE_SZ+1 : SIZE_SZ+1);
i > sz;
i -= 0xFF) {
if(i-sz < 0x100) {
m_ptr[i] = (unsigned char)(i-sz);
break;
}
m_ptr[i] = 0xFF;
}
m_ptr[sz] = MAGICBYTE(p);
return (Void_t*)m_ptr;
}
/* Convert a pointer to be free()d or realloc()ed to a valid chunk
pointer. If the provided pointer is not valid, return NULL. */
static mchunkptr
internal_function
#if __STD_C
mem2chunk_check(Void_t* mem)
#else
mem2chunk_check(mem) Void_t* mem;
#endif
{
mchunkptr p;
INTERNAL_SIZE_T sz, c;
unsigned char magic;
p = mem2chunk(mem);
if(!aligned_OK(p)) return NULL;
if( (char*)p>=sbrk_base && (char*)p<(sbrk_base+sbrked_mem) ) {
/* Must be a chunk in conventional heap memory. */
if(chunk_is_mmapped(p) ||
( (sz = chunksize(p)), ((char*)p + sz)>=(sbrk_base+sbrked_mem) ) ||
sz<MINSIZE || sz&MALLOC_ALIGN_MASK || !inuse(p) ||
( !prev_inuse(p) && (p->prev_size&MALLOC_ALIGN_MASK ||
(long)prev_chunk(p)<(long)sbrk_base ||
next_chunk(prev_chunk(p))!=p) ))
return NULL;
magic = MAGICBYTE(p);
for(sz += SIZE_SZ-1; (c = ((unsigned char*)p)[sz]) != magic; sz -= c) {
if(c<=0 || sz<(c+2*SIZE_SZ)) return NULL;
}
((unsigned char*)p)[sz] ^= 0xFF;
} else {
unsigned long offset, page_mask = malloc_getpagesize-1;
/* mmap()ed chunks have MALLOC_ALIGNMENT or higher power-of-two
alignment relative to the beginning of a page. Check this
first. */
offset = (unsigned long)mem & page_mask;
if((offset!=MALLOC_ALIGNMENT && offset!=0 && offset!=0x10 &&
offset!=0x20 && offset!=0x40 && offset!=0x80 && offset!=0x100 &&
offset!=0x200 && offset!=0x400 && offset!=0x800 && offset!=0x1000 &&
offset<0x2000) ||
!chunk_is_mmapped(p) || (p->size & PREV_INUSE) ||
( (((unsigned long)p - p->prev_size) & page_mask) != 0 ) ||
( (sz = chunksize(p)), ((p->prev_size + sz) & page_mask) != 0 ) )
return NULL;
magic = MAGICBYTE(p);
for(sz -= 1; (c = ((unsigned char*)p)[sz]) != magic; sz -= c) {
if(c<=0 || sz<(c+2*SIZE_SZ)) return NULL;
}
((unsigned char*)p)[sz] ^= 0xFF;
}
return p;
}
/* Check for corruption of the top chunk, and try to recover if
necessary. */
static int
internal_function
#if __STD_C
top_check(void)
#else
top_check()
#endif
{
mchunkptr t = top(&main_arena);
char* brk, * new_brk;
INTERNAL_SIZE_T front_misalign, sbrk_size;
unsigned long pagesz = malloc_getpagesize;
if((char*)t + chunksize(t) == sbrk_base + sbrked_mem ||
t == initial_top(&main_arena)) return 0;
if(check_action & 1)
fprintf(stderr, "malloc: top chunk is corrupt\n");
if(check_action & 2)
abort();
/* Try to set up a new top chunk. */
brk = MORECORE(0);
front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK;
if (front_misalign > 0)
front_misalign = MALLOC_ALIGNMENT - front_misalign;
sbrk_size = front_misalign + top_pad + MINSIZE;
sbrk_size += pagesz - ((unsigned long)(brk + sbrk_size) & (pagesz - 1));
new_brk = (char*)(MORECORE (sbrk_size));
if (new_brk == (char*)(MORECORE_FAILURE)) return -1;
sbrked_mem = (new_brk - sbrk_base) + sbrk_size;
top(&main_arena) = (mchunkptr)(brk + front_misalign);
set_head(top(&main_arena), (sbrk_size - front_misalign) | PREV_INUSE);
return 0;
}
static Void_t*
#if __STD_C
malloc_check(size_t sz, const Void_t *caller)
#else
malloc_check(sz, caller) size_t sz; const Void_t *caller;
#endif
{
mchunkptr victim;
INTERNAL_SIZE_T nb;
if(request2size(sz+1, nb))
return 0;
(void)mutex_lock(&main_arena.mutex);
victim = (top_check() >= 0) ? chunk_alloc(&main_arena, nb) : NULL;
(void)mutex_unlock(&main_arena.mutex);
if(!victim) return NULL;
return chunk2mem_check(victim, sz);
}
static void
#if __STD_C
free_check(Void_t* mem, const Void_t *caller)
#else
free_check(mem, caller) Void_t* mem; const Void_t *caller;
#endif
{
mchunkptr p;
if(!mem) return;
(void)mutex_lock(&main_arena.mutex);
p = mem2chunk_check(mem);
if(!p) {
(void)mutex_unlock(&main_arena.mutex);
if(check_action & 1)
fprintf(stderr, "free(): invalid pointer %p!\n", mem);
if(check_action & 2)
abort();
return;
}
#if HAVE_MMAP
if (chunk_is_mmapped(p)) {
(void)mutex_unlock(&main_arena.mutex);
munmap_chunk(p);
return;
}
#endif
#if 0 /* Erase freed memory. */
memset(mem, 0, chunksize(p) - (SIZE_SZ+1));
#endif
chunk_free(&main_arena, p);
(void)mutex_unlock(&main_arena.mutex);
}
static Void_t*
#if __STD_C
realloc_check(Void_t* oldmem, size_t bytes, const Void_t *caller)
#else
realloc_check(oldmem, bytes, caller)
Void_t* oldmem; size_t bytes; const Void_t *caller;
#endif
{
mchunkptr oldp, newp;
INTERNAL_SIZE_T nb, oldsize;
if (oldmem == 0) return malloc_check(bytes, NULL);
(void)mutex_lock(&main_arena.mutex);
oldp = mem2chunk_check(oldmem);
if(!oldp) {
(void)mutex_unlock(&main_arena.mutex);
if(check_action & 1)
fprintf(stderr, "realloc(): invalid pointer %p!\n", oldmem);
if(check_action & 2)
abort();
return malloc_check(bytes, NULL);
}
oldsize = chunksize(oldp);
if(request2size(bytes+1, nb)) {
(void)mutex_unlock(&main_arena.mutex);
return 0;
}
#if HAVE_MMAP
if (chunk_is_mmapped(oldp)) {
#if HAVE_MREMAP
newp = mremap_chunk(oldp, nb);
if(!newp) {
#endif
/* Note the extra SIZE_SZ overhead. */
if(oldsize - SIZE_SZ >= nb) newp = oldp; /* do nothing */
else {
/* Must alloc, copy, free. */
newp = (top_check() >= 0) ? chunk_alloc(&main_arena, nb) : NULL;
if (newp) {
MALLOC_COPY(BOUNDED_N(chunk2mem(newp), nb),
oldmem, oldsize - 2*SIZE_SZ, 0);
munmap_chunk(oldp);
}
}
#if HAVE_MREMAP
}
#endif
} else {
#endif /* HAVE_MMAP */
newp = (top_check() >= 0) ?
chunk_realloc(&main_arena, oldp, oldsize, nb) : NULL;
#if 0 /* Erase freed memory. */
nb = chunksize(newp);
if(oldp<newp || oldp>=chunk_at_offset(newp, nb)) {
memset((char*)oldmem + 2*sizeof(mbinptr), 0,
oldsize - (2*sizeof(mbinptr)+2*SIZE_SZ+1));
} else if(nb > oldsize+SIZE_SZ) {
memset((char*)BOUNDED_N(chunk2mem(newp), bytes) + oldsize,
0, nb - (oldsize+SIZE_SZ));
}
#endif
#if HAVE_MMAP
}
#endif
(void)mutex_unlock(&main_arena.mutex);
if(!newp) return NULL;
return chunk2mem_check(newp, bytes);
}
static Void_t*
#if __STD_C
memalign_check(size_t alignment, size_t bytes, const Void_t *caller)
#else
memalign_check(alignment, bytes, caller)
size_t alignment; size_t bytes; const Void_t *caller;
#endif
{
INTERNAL_SIZE_T nb;
mchunkptr p;
if (alignment <= MALLOC_ALIGNMENT) return malloc_check(bytes, NULL);
if (alignment < MINSIZE) alignment = MINSIZE;
if(request2size(bytes+1, nb))
return 0;
(void)mutex_lock(&main_arena.mutex);
p = (top_check() >= 0) ? chunk_align(&main_arena, nb, alignment) : NULL;
(void)mutex_unlock(&main_arena.mutex);
if(!p) return NULL;
return chunk2mem_check(p, bytes);
}
#ifndef NO_THREADS
/* The following hooks are used when the global initialization in
ptmalloc_init() hasn't completed yet. */
static Void_t*
#if __STD_C
malloc_starter(size_t sz, const Void_t *caller)
#else
malloc_starter(sz, caller) size_t sz; const Void_t *caller;
#endif
{
INTERNAL_SIZE_T nb;
mchunkptr victim;
if(request2size(sz, nb))
return 0;
victim = chunk_alloc(&main_arena, nb);
return victim ? BOUNDED_N(chunk2mem(victim), sz) : 0;
}
static void
#if __STD_C
free_starter(Void_t* mem, const Void_t *caller)
#else
free_starter(mem, caller) Void_t* mem; const Void_t *caller;
#endif
{
mchunkptr p;
if(!mem) return;
p = mem2chunk(mem);
#if HAVE_MMAP
if (chunk_is_mmapped(p)) {
munmap_chunk(p);
return;
}
#endif
chunk_free(&main_arena, p);
}
/* The following hooks are used while the `atfork' handling mechanism
is active. */
static Void_t*
#if __STD_C
malloc_atfork (size_t sz, const Void_t *caller)
#else
malloc_atfork(sz, caller) size_t sz; const Void_t *caller;
#endif
{
Void_t *vptr = NULL;
INTERNAL_SIZE_T nb;
mchunkptr victim;
tsd_getspecific(arena_key, vptr);
if(vptr == ATFORK_ARENA_PTR) {
/* We are the only thread that may allocate at all. */
if(save_malloc_hook != malloc_check) {
if(request2size(sz, nb))
return 0;
victim = chunk_alloc(&main_arena, nb);
return victim ? BOUNDED_N(chunk2mem(victim), sz) : 0;
} else {
if(top_check()<0 || request2size(sz+1, nb))
return 0;
victim = chunk_alloc(&main_arena, nb);
return victim ? chunk2mem_check(victim, sz) : 0;
}
} else {
/* Suspend the thread until the `atfork' handlers have completed.
By that time, the hooks will have been reset as well, so that
mALLOc() can be used again. */
(void)mutex_lock(&list_lock);
(void)mutex_unlock(&list_lock);
return mALLOc(sz);
}
}
static void
#if __STD_C
free_atfork(Void_t* mem, const Void_t *caller)
#else
free_atfork(mem, caller) Void_t* mem; const Void_t *caller;
#endif
{
Void_t *vptr = NULL;
arena *ar_ptr;
mchunkptr p; /* chunk corresponding to mem */
if (mem == 0) /* free(0) has no effect */
return;
p = mem2chunk(mem); /* do not bother to replicate free_check here */
#if HAVE_MMAP
if (chunk_is_mmapped(p)) /* release mmapped memory. */
{
munmap_chunk(p);
return;
}
#endif
ar_ptr = arena_for_ptr(p);
tsd_getspecific(arena_key, vptr);
if(vptr != ATFORK_ARENA_PTR)
(void)mutex_lock(&ar_ptr->mutex);
chunk_free(ar_ptr, p);
if(vptr != ATFORK_ARENA_PTR)
(void)mutex_unlock(&ar_ptr->mutex);
}
#endif /* !defined NO_THREADS */
#endif /* defined _LIBC || defined MALLOC_HOOKS */
#ifdef _LIBC
/* default method of getting more storage */
__malloc_ptr_t
__default_morecore (int inc)
{
__malloc_ptr_t result = (__malloc_ptr_t)sbrk (inc);
if (result == (__malloc_ptr_t)-1)
return NULL;
return result;
}
/* We need a wrapper function for one of the additions of POSIX. */
int
__posix_memalign (void **memptr, size_t alignment, size_t size)
{
void *mem;
/* Test whether the ALIGNMENT argument is valid. It must be a power
of two multiple of sizeof (void *). */
if (alignment % sizeof (void *) != 0 || (alignment & (alignment - 1)) != 0)
return EINVAL;
mem = __libc_memalign (alignment, size);
if (mem != NULL)
{
*memptr = mem;
return 0;
}
return ENOMEM;
}
weak_alias (__posix_memalign, posix_memalign)
weak_alias (__libc_calloc, __calloc) weak_alias (__libc_calloc, calloc)
weak_alias (__libc_free, __cfree) weak_alias (__libc_free, cfree)
weak_alias (__libc_free, __free) weak_alias (__libc_free, free)
weak_alias (__libc_malloc, __malloc) weak_alias (__libc_malloc, malloc)
weak_alias (__libc_memalign, __memalign) weak_alias (__libc_memalign, memalign)
weak_alias (__libc_realloc, __realloc) weak_alias (__libc_realloc, realloc)
weak_alias (__libc_valloc, __valloc) weak_alias (__libc_valloc, valloc)
weak_alias (__libc_pvalloc, __pvalloc) weak_alias (__libc_pvalloc, pvalloc)
weak_alias (__libc_mallinfo, __mallinfo) weak_alias (__libc_mallinfo, mallinfo)
weak_alias (__libc_mallopt, __mallopt) weak_alias (__libc_mallopt, mallopt)
weak_alias (__malloc_stats, malloc_stats)
weak_alias (__malloc_usable_size, malloc_usable_size)
weak_alias (__malloc_trim, malloc_trim)
weak_alias (__malloc_get_state, malloc_get_state)
weak_alias (__malloc_set_state, malloc_set_state)
#endif
/*
History:
V2.6.4-pt3 Thu Feb 20 1997 Wolfram Gloger ([email protected])
* Added malloc_get/set_state() (mainly for use in GNU emacs),
using interface from Marcus Daniels
* All parameters are now adjustable via environment variables
V2.6.4-pt2 Sat Dec 14 1996 Wolfram Gloger ([email protected])
* Added debugging hooks
* Fixed possible deadlock in realloc() when out of memory
* Don't pollute namespace in glibc: use __getpagesize, __mmap, etc.
V2.6.4-pt Wed Dec 4 1996 Wolfram Gloger ([email protected])
* Very minor updates from the released 2.6.4 version.
* Trimmed include file down to exported data structures.
* Changes from H.J. Lu for glibc-2.0.
V2.6.3i-pt Sep 16 1996 Wolfram Gloger ([email protected])
* Many changes for multiple threads
* Introduced arenas and heaps
V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee)
* Added pvalloc, as recommended by H.J. Liu
* Added 64bit pointer support mainly from Wolfram Gloger
* Added anonymously donated WIN32 sbrk emulation
* Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen
* malloc_extend_top: fix mask error that caused wastage after
foreign sbrks
* Add linux mremap support code from HJ Liu
V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee)
* Integrated most documentation with the code.
* Add support for mmap, with help from
Wolfram Gloger ([email protected]).
* Use last_remainder in more cases.
* Pack bins using idea from [email protected]
* Use ordered bins instead of best-fit threshold
* Eliminate block-local decls to simplify tracing and debugging.
* Support another case of realloc via move into top
* Fix error occurring when initial sbrk_base not word-aligned.
* Rely on page size for units instead of SBRK_UNIT to
avoid surprises about sbrk alignment conventions.
* Add mallinfo, mallopt. Thanks to Raymond Nijssen
([email protected]) for the suggestion.
* Add `pad' argument to malloc_trim and top_pad mallopt parameter.
* More precautions for cases where other routines call sbrk,
courtesy of Wolfram Gloger ([email protected]).
* Added macros etc., allowing use in linux libc from
H.J. Lu ([email protected])
* Inverted this history list
V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee)
* Re-tuned and fixed to behave more nicely with V2.6.0 changes.
* Removed all preallocation code since under current scheme
the work required to undo bad preallocations exceeds
the work saved in good cases for most test programs.
* No longer use return list or unconsolidated bins since
no scheme using them consistently outperforms those that don't
given above changes.
* Use best fit for very large chunks to prevent some worst-cases.
* Added some support for debugging
V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee)
* Removed footers when chunks are in use. Thanks to
Paul Wilson ([email protected]) for the suggestion.
V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee)
* Added malloc_trim, with help from Wolfram Gloger
([email protected]).
V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g)
V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g)
* realloc: try to expand in both directions
* malloc: swap order of clean-bin strategy;
* realloc: only conditionally expand backwards
* Try not to scavenge used bins
* Use bin counts as a guide to preallocation
* Occasionally bin return list chunks in first scan
* Add a few optimizations from [email protected]
V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g)
* faster bin computation & slightly different binning
* merged all consolidations to one part of malloc proper
(eliminating old malloc_find_space & malloc_clean_bin)
* Scan 2 returns chunks (not just 1)
* Propagate failure in realloc if malloc returns 0
* Add stuff to allow compilation on non-ANSI compilers
from [email protected]
V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu)
* removed potential for odd address access in prev_chunk
* removed dependency on getpagesize.h
* misc cosmetics and a bit more internal documentation
* anticosmetics: mangled names in macros to evade debugger strangeness
* tested on sparc, hp-700, dec-mips, rs6000
with gcc & native cc (hp, dec only) allowing
Detlefs & Zorn comparison study (in SIGPLAN Notices.)
Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu)
* Based loosely on libg++-1.2X malloc. (It retains some of the overall
structure of old version, but most details differ.)
*/
Raw
malloc-2.7.0.c
/* Malloc implementation for multiple threads without lock contention.
Copyright (C) 1996-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Wolfram Gloger <[email protected]>
and Doug Lea <[email protected]>, 2001.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, see <http://www.gnu.org/licenses/>. */
/*
This is a version (aka ptmalloc2) of malloc/free/realloc written by
Doug Lea and adapted to multiple threads/arenas by Wolfram Gloger.
There have been substantial changes made after the integration into
glibc in all parts of the code. Do not look for much commonality
with the ptmalloc2 version.
* Version ptmalloc2-20011215
based on:
VERSION 2.7.0 Sun Mar 11 14:14:06 2001 Doug Lea (dl at gee)
* Quickstart
In order to compile this implementation, a Makefile is provided with
the ptmalloc2 distribution, which has pre-defined targets for some
popular systems (e.g. "make posix" for Posix threads). All that is
typically required with regard to compiler flags is the selection of
the thread package via defining one out of USE_PTHREADS, USE_THR or
USE_SPROC. Check the thread-m.h file for what effects this has.
Many/most systems will additionally require USE_TSD_DATA_HACK to be
defined, so this is the default for "make posix".
* Why use this malloc?
This is not the fastest, most space-conserving, most portable, or
most tunable malloc ever written. However it is among the fastest
while also being among the most space-conserving, portable and tunable.
Consistent balance across these factors results in a good general-purpose
allocator for malloc-intensive programs.
The main properties of the algorithms are:
* For large (>= 512 bytes) requests, it is a pure best-fit allocator,
with ties normally decided via FIFO (i.e. least recently used).
* For small (<= 64 bytes by default) requests, it is a caching
allocator, that maintains pools of quickly recycled chunks.
* In between, and for combinations of large and small requests, it does
the best it can trying to meet both goals at once.
* For very large requests (>= 128KB by default), it relies on system
memory mapping facilities, if supported.
For a longer but slightly out of date high-level description, see
http://gee.cs.oswego.edu/dl/html/malloc.html
You may already by default be using a C library containing a malloc
that is based on some version of this malloc (for example in
linux). You might still want to use the one in this file in order to
customize settings or to avoid overheads associated with library
versions.
* Contents, described in more detail in "description of public routines" below.
Standard (ANSI/SVID/...) functions:
malloc(size_t n);
calloc(size_t n_elements, size_t element_size);
free(void* p);
realloc(void* p, size_t n);
memalign(size_t alignment, size_t n);
valloc(size_t n);
mallinfo()
mallopt(int parameter_number, int parameter_value)
Additional functions:
independent_calloc(size_t n_elements, size_t size, void* chunks[]);
independent_comalloc(size_t n_elements, size_t sizes[], void* chunks[]);
pvalloc(size_t n);
malloc_trim(size_t pad);
malloc_usable_size(void* p);
malloc_stats();
* Vital statistics:
Supported pointer representation: 4 or 8 bytes
Supported size_t representation: 4 or 8 bytes
Note that size_t is allowed to be 4 bytes even if pointers are 8.
You can adjust this by defining INTERNAL_SIZE_T
Alignment: 2 * sizeof(size_t) (default)
(i.e., 8 byte alignment with 4byte size_t). This suffices for
nearly all current machines and C compilers. However, you can
define MALLOC_ALIGNMENT to be wider than this if necessary.
Minimum overhead per allocated chunk: 4 or 8 bytes
Each malloced chunk has a hidden word of overhead holding size
and status information.
Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
needed; 4 (8) for a trailing size field and 8 (16) bytes for
free list pointers. Thus, the minimum allocatable size is
16/24/32 bytes.
Even a request for zero bytes (i.e., malloc(0)) returns a
pointer to something of the minimum allocatable size.
The maximum overhead wastage (i.e., number of extra bytes
allocated than were requested in malloc) is less than or equal
to the minimum size, except for requests >= mmap_threshold that
are serviced via mmap(), where the worst case wastage is 2 *
sizeof(size_t) bytes plus the remainder from a system page (the
minimal mmap unit); typically 4096 or 8192 bytes.
Maximum allocated size: 4-byte size_t: 2^32 minus about two pages
8-byte size_t: 2^64 minus about two pages
It is assumed that (possibly signed) size_t values suffice to
represent chunk sizes. `Possibly signed' is due to the fact
that `size_t' may be defined on a system as either a signed or
an unsigned type. The ISO C standard says that it must be
unsigned, but a few systems are known not to adhere to this.
Additionally, even when size_t is unsigned, sbrk (which is by
default used to obtain memory from system) accepts signed
arguments, and may not be able to handle size_t-wide arguments
with negative sign bit. Generally, values that would
appear as negative after accounting for overhead and alignment
are supported only via mmap(), which does not have this
limitation.
Requests for sizes outside the allowed range will perform an optional
failure action and then return null. (Requests may also
also fail because a system is out of memory.)
Thread-safety: thread-safe
Compliance: I believe it is compliant with the 1997 Single Unix Specification
Also SVID/XPG, ANSI C, and probably others as well.
* Synopsis of compile-time options:
People have reported using previous versions of this malloc on all
versions of Unix, sometimes by tweaking some of the defines
below. It has been tested most extensively on Solaris and Linux.
People also report using it in stand-alone embedded systems.
The implementation is in straight, hand-tuned ANSI C. It is not
at all modular. (Sorry!) It uses a lot of macros. To be at all
usable, this code should be compiled using an optimizing compiler
(for example gcc -O3) that can simplify expressions and control
paths. (FAQ: some macros import variables as arguments rather than
declare locals because people reported that some debuggers
otherwise get confused.)
OPTION DEFAULT VALUE
Compilation Environment options:
HAVE_MREMAP 0
Changing default word sizes:
INTERNAL_SIZE_T size_t
Configuration and functionality options:
USE_PUBLIC_MALLOC_WRAPPERS NOT defined
USE_MALLOC_LOCK NOT defined
MALLOC_DEBUG NOT defined
REALLOC_ZERO_BYTES_FREES 1
TRIM_FASTBINS 0
Options for customizing MORECORE:
MORECORE sbrk
MORECORE_FAILURE -1
MORECORE_CONTIGUOUS 1
MORECORE_CANNOT_TRIM NOT defined
MORECORE_CLEARS 1
MMAP_AS_MORECORE_SIZE (1024 * 1024)
Tuning options that are also dynamically changeable via mallopt:
DEFAULT_MXFAST 64 (for 32bit), 128 (for 64bit)
DEFAULT_TRIM_THRESHOLD 128 * 1024
DEFAULT_TOP_PAD 0
DEFAULT_MMAP_THRESHOLD 128 * 1024
DEFAULT_MMAP_MAX 65536
There are several other #defined constants and macros that you
probably don't want to touch unless you are extending or adapting malloc. */
/*
void* is the pointer type that malloc should say it returns
*/
#ifndef void
#define void void
#endif /*void*/
#include <stddef.h> /* for size_t */
#include <stdlib.h> /* for getenv(), abort() */
#include <unistd.h> /* for __libc_enable_secure */
#include <atomic.h>
#include <_itoa.h>
#include <bits/wordsize.h>
#include <sys/sysinfo.h>
#include <ldsodefs.h>
#include <unistd.h>
#include <stdio.h> /* needed for malloc_stats */
#include <errno.h>
#include <assert.h>
#include <shlib-compat.h>
/* For uintptr_t. */
#include <stdint.h>
/* For va_arg, va_start, va_end. */
#include <stdarg.h>
/* For MIN, MAX, powerof2. */
#include <sys/param.h>
/* For ALIGN_UP et. al. */
#include <libc-pointer-arith.h>
/* For DIAG_PUSH/POP_NEEDS_COMMENT et al. */
#include <libc-diag.h>
#include <malloc/malloc-internal.h>
/* For SINGLE_THREAD_P. */
#include <sysdep-cancel.h>
/*
Debugging:
Because freed chunks may be overwritten with bookkeeping fields, this
malloc will often die when freed memory is overwritten by user
programs. This can be very effective (albeit in an annoying way)
in helping track down dangling pointers.
If you compile with -DMALLOC_DEBUG, a number of assertion checks are
enabled that will catch more memory errors. You probably won't be
able to make much sense of the actual assertion errors, but they
should help you locate incorrectly overwritten memory. The checking
is fairly extensive, and will slow down execution
noticeably. Calling malloc_stats or mallinfo with MALLOC_DEBUG set
will attempt to check every non-mmapped allocated and free chunk in
the course of computing the summmaries. (By nature, mmapped regions
cannot be checked very much automatically.)
Setting MALLOC_DEBUG may also be helpful if you are trying to modify
this code. The assertions in the check routines spell out in more
detail the assumptions and invariants underlying the algorithms.
Setting MALLOC_DEBUG does NOT provide an automated mechanism for
checking that all accesses to malloced memory stay within their
bounds. However, there are several add-ons and adaptations of this
or other mallocs available that do this.
*/
#ifndef MALLOC_DEBUG
#define MALLOC_DEBUG 0
#endif
#ifndef NDEBUG
# define __assert_fail(assertion, file, line, function) \
__malloc_assert(assertion, file, line, function)
extern const char *__progname;
static void
__malloc_assert (const char *assertion, const char *file, unsigned int line,
const char *function)
{
(void) __fxprintf (NULL, "%s%s%s:%u: %s%sAssertion `%s' failed.\n",
__progname, __progname[0] ? ": " : "",
file, line,
function ? function : "", function ? ": " : "",
assertion);
fflush (stderr);
abort ();
}
#endif
#if USE_TCACHE
/* We want 64 entries. This is an arbitrary limit, which tunables can reduce. */
# define TCACHE_MAX_BINS 64
# define MAX_TCACHE_SIZE tidx2usize (TCACHE_MAX_BINS-1)
/* Only used to pre-fill the tunables. */
# define tidx2usize(idx) (((size_t) idx) * MALLOC_ALIGNMENT + MINSIZE - SIZE_SZ)
/* When "x" is from chunksize(). */
# define csize2tidx(x) (((x) - MINSIZE + MALLOC_ALIGNMENT - 1) / MALLOC_ALIGNMENT)
/* When "x" is a user-provided size. */
# define usize2tidx(x) csize2tidx (request2size (x))
/* With rounding and alignment, the bins are...
idx 0 bytes 0..24 (64-bit) or 0..12 (32-bit)
idx 1 bytes 25..40 or 13..20
idx 2 bytes 41..56 or 21..28
etc. */
/* This is another arbitrary limit, which tunables can change. Each
tcache bin will hold at most this number of chunks. */
# define TCACHE_FILL_COUNT 7
#endif
/*
REALLOC_ZERO_BYTES_FREES should be set if a call to
realloc with zero bytes should be the same as a call to free.
This is required by the C standard. Otherwise, since this malloc
returns a unique pointer for malloc(0), so does realloc(p, 0).
*/
#ifndef REALLOC_ZERO_BYTES_FREES
#define REALLOC_ZERO_BYTES_FREES 1
#endif
/*
TRIM_FASTBINS controls whether free() of a very small chunk can
immediately lead to trimming. Setting to true (1) can reduce memory
footprint, but will almost always slow down programs that use a lot
of small chunks.
Define this only if you are willing to give up some speed to more
aggressively reduce system-level memory footprint when releasing
memory in programs that use many small chunks. You can get
essentially the same effect by setting MXFAST to 0, but this can
lead to even greater slowdowns in programs using many small chunks.
TRIM_FASTBINS is an in-between compile-time option, that disables
only those chunks bordering topmost memory from being placed in
fastbins.
*/
#ifndef TRIM_FASTBINS
#define TRIM_FASTBINS 0
#endif
/* Definition for getting more memory from the OS. */
#define MORECORE (*__morecore)
#define MORECORE_FAILURE 0
void * __default_morecore (ptrdiff_t);
void *(*__morecore)(ptrdiff_t) = __default_morecore;
#include <string.h>
/*
MORECORE-related declarations. By default, rely on sbrk
*/
/*
MORECORE is the name of the routine to call to obtain more memory
from the system. See below for general guidance on writing
alternative MORECORE functions, as well as a version for WIN32 and a
sample version for pre-OSX macos.
*/
#ifndef MORECORE
#define MORECORE sbrk
#endif
/*
MORECORE_FAILURE is the value returned upon failure of MORECORE
as well as mmap. Since it cannot be an otherwise valid memory address,
and must reflect values of standard sys calls, you probably ought not
try to redefine it.
*/
#ifndef MORECORE_FAILURE
#define MORECORE_FAILURE (-1)
#endif
/*
If MORECORE_CONTIGUOUS is true, take advantage of fact that
consecutive calls to MORECORE with positive arguments always return
contiguous increasing addresses. This is true of unix sbrk. Even
if not defined, when regions happen to be contiguous, malloc will
permit allocations spanning regions obtained from different
calls. But defining this when applicable enables some stronger
consistency checks and space efficiencies.
*/
#ifndef MORECORE_CONTIGUOUS
#define MORECORE_CONTIGUOUS 1
#endif
/*
Define MORECORE_CANNOT_TRIM if your version of MORECORE
cannot release space back to the system when given negative
arguments. This is generally necessary only if you are using
a hand-crafted MORECORE function that cannot handle negative arguments.
*/
/* #define MORECORE_CANNOT_TRIM */
/* MORECORE_CLEARS (default 1)
The degree to which the routine mapped to MORECORE zeroes out
memory: never (0), only for newly allocated space (1) or always
(2). The distinction between (1) and (2) is necessary because on
some systems, if the application first decrements and then
increments the break value, the contents of the reallocated space
are unspecified.
*/
#ifndef MORECORE_CLEARS
# define MORECORE_CLEARS 1
#endif
/*
MMAP_AS_MORECORE_SIZE is the minimum mmap size argument to use if
sbrk fails, and mmap is used as a backup. The value must be a
multiple of page size. This backup strategy generally applies only
when systems have "holes" in address space, so sbrk cannot perform
contiguous expansion, but there is still space available on system.
On systems for which this is known to be useful (i.e. most linux
kernels), this occurs only when programs allocate huge amounts of
memory. Between this, and the fact that mmap regions tend to be
limited, the size should be large, to avoid too many mmap calls and
thus avoid running out of kernel resources. */
#ifndef MMAP_AS_MORECORE_SIZE
#define MMAP_AS_MORECORE_SIZE (1024 * 1024)
#endif
/*
Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
large blocks.
*/
#ifndef HAVE_MREMAP
#define HAVE_MREMAP 0
#endif
/* We may need to support __malloc_initialize_hook for backwards
compatibility. */
#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_24)
# define HAVE_MALLOC_INIT_HOOK 1
#else
# define HAVE_MALLOC_INIT_HOOK 0
#endif
/*
This version of malloc supports the standard SVID/XPG mallinfo
routine that returns a struct containing usage properties and
statistics. It should work on any SVID/XPG compliant system that has
a /usr/include/malloc.h defining struct mallinfo. (If you'd like to
install such a thing yourself, cut out the preliminary declarations
as described above and below and save them in a malloc.h file. But
there's no compelling reason to bother to do this.)
The main declaration needed is the mallinfo struct that is returned
(by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
bunch of fields that are not even meaningful in this version of
malloc. These fields are are instead filled by mallinfo() with
other numbers that might be of interest.
*/
/* ---------- description of public routines ------------ */
/*
malloc(size_t n)
Returns a pointer to a newly allocated chunk of at least n bytes, or null
if no space is available. Additionally, on failure, errno is
set to ENOMEM on ANSI C systems.
If n is zero, malloc returns a minumum-sized chunk. (The minimum
size is 16 bytes on most 32bit systems, and 24 or 32 bytes on 64bit
systems.) On most systems, size_t is an unsigned type, so calls
with negative arguments are interpreted as requests for huge amounts
of space, which will often fail. The maximum supported value of n
differs across systems, but is in all cases less than the maximum
representable value of a size_t.
*/
void* __libc_malloc(size_t);
libc_hidden_proto (__libc_malloc)
/*
free(void* p)
Releases the chunk of memory pointed to by p, that had been previously
allocated using malloc or a related routine such as realloc.
It has no effect if p is null. It can have arbitrary (i.e., bad!)
effects if p has already been freed.
Unless disabled (using mallopt), freeing very large spaces will
when possible, automatically trigger operations that give
back unused memory to the system, thus reducing program footprint.
*/
void __libc_free(void*);
libc_hidden_proto (__libc_free)
/*
calloc(size_t n_elements, size_t element_size);
Returns a pointer to n_elements * element_size bytes, with all locations
set to zero.
*/
void* __libc_calloc(size_t, size_t);
/*
realloc(void* p, size_t n)
Returns a pointer to a chunk of size n that contains the same data
as does chunk p up to the minimum of (n, p's size) bytes, or null
if no space is available.
The returned pointer may or may not be the same as p. The algorithm
prefers extending p when possible, otherwise it employs the
equivalent of a malloc-copy-free sequence.
If p is null, realloc is equivalent to malloc.
If space is not available, realloc returns null, errno is set (if on
ANSI) and p is NOT freed.
if n is for fewer bytes than already held by p, the newly unused
space is lopped off and freed if possible. Unless the #define
REALLOC_ZERO_BYTES_FREES is set, realloc with a size argument of
zero (re)allocates a minimum-sized chunk.
Large chunks that were internally obtained via mmap will always be
grown using malloc-copy-free sequences unless the system supports
MREMAP (currently only linux).
The old unix realloc convention of allowing the last-free'd chunk
to be used as an argument to realloc is not supported.
*/
void* __libc_realloc(void*, size_t);
libc_hidden_proto (__libc_realloc)
/*
memalign(size_t alignment, size_t n);
Returns a pointer to a newly allocated chunk of n bytes, aligned
in accord with the alignment argument.
The alignment argument should be a power of two. If the argument is
not a power of two, the nearest greater power is used.
8-byte alignment is guaranteed by normal malloc calls, so don't
bother calling memalign with an argument of 8 or less.
Overreliance on memalign is a sure way to fragment space.
*/
void* __libc_memalign(size_t, size_t);
libc_hidden_proto (__libc_memalign)
/*
valloc(size_t n);
Equivalent to memalign(pagesize, n), where pagesize is the page
size of the system. If the pagesize is unknown, 4096 is used.
*/
void* __libc_valloc(size_t);
/*
mallopt(int parameter_number, int parameter_value)
Sets tunable parameters The format is to provide a
(parameter-number, parameter-value) pair. mallopt then sets the
corresponding parameter to the argument value if it can (i.e., so
long as the value is meaningful), and returns 1 if successful else
0. SVID/XPG/ANSI defines four standard param numbers for mallopt,
normally defined in malloc.h. Only one of these (M_MXFAST) is used
in this malloc. The others (M_NLBLKS, M_GRAIN, M_KEEP) don't apply,
so setting them has no effect. But this malloc also supports four
other options in mallopt. See below for details. Briefly, supported
parameters are as follows (listed defaults are for "typical"
configurations).
Symbol param # default allowed param values
M_MXFAST 1 64 0-80 (0 disables fastbins)
M_TRIM_THRESHOLD -1 128*1024 any (-1U disables trimming)
M_TOP_PAD -2 0 any
M_MMAP_THRESHOLD -3 128*1024 any (or 0 if no MMAP support)
M_MMAP_MAX -4 65536 any (0 disables use of mmap)
*/
int __libc_mallopt(int, int);
libc_hidden_proto (__libc_mallopt)
/*
mallinfo()
Returns (by copy) a struct containing various summary statistics:
arena: current total non-mmapped bytes allocated from system
ordblks: the number of free chunks
smblks: the number of fastbin blocks (i.e., small chunks that
have been freed but not use resused or consolidated)
hblks: current number of mmapped regions
hblkhd: total bytes held in mmapped regions
usmblks: always 0
fsmblks: total bytes held in fastbin blocks
uordblks: current total allocated space (normal or mmapped)
fordblks: total free space
keepcost: the maximum number of bytes that could ideally be released
back to system via malloc_trim. ("ideally" means that
it ignores page restrictions etc.)
Because these fields are ints, but internal bookkeeping may
be kept as longs, the reported values may wrap around zero and
thus be inaccurate.
*/
struct mallinfo __libc_mallinfo(void);
/*
pvalloc(size_t n);
Equivalent to valloc(minimum-page-that-holds(n)), that is,
round up n to nearest pagesize.
*/
void* __libc_pvalloc(size_t);
/*
malloc_trim(size_t pad);
If possible, gives memory back to the system (via negative
arguments to sbrk) if there is unused memory at the `high' end of
the malloc pool. You can call this after freeing large blocks of
memory to potentially reduce the system-level memory requirements
of a program. However, it cannot guarantee to reduce memory. Under
some allocation patterns, some large free blocks of memory will be
locked between two used chunks, so they cannot be given back to
the system.
The `pad' argument to malloc_trim represents the amount of free
trailing space to leave untrimmed. If this argument is zero,
only the minimum amount of memory to maintain internal data
structures will be left (one page or less). Non-zero arguments
can be supplied to maintain enough trailing space to service
future expected allocations without having to re-obtain memory
from the system.
Malloc_trim returns 1 if it actually released any memory, else 0.
On systems that do not support "negative sbrks", it will always
return 0.
*/
int __malloc_trim(size_t);
/*
malloc_usable_size(void* p);
Returns the number of bytes you can actually use in
an allocated chunk, which may be more than you requested (although
often not) due to alignment and minimum size constraints.
You can use this many bytes without worrying about
overwriting other allocated objects. This is not a particularly great
programming practice. malloc_usable_size can be more useful in
debugging and assertions, for example:
p = malloc(n);
assert(malloc_usable_size(p) >= 256);
*/
size_t __malloc_usable_size(void*);
/*
malloc_stats();
Prints on stderr the amount of space obtained from the system (both
via sbrk and mmap), the maximum amount (which may be more than
current if malloc_trim and/or munmap got called), and the current
number of bytes allocated via malloc (or realloc, etc) but not yet
freed. Note that this is the number of bytes allocated, not the
number requested. It will be larger than the number requested
because of alignment and bookkeeping overhead. Because it includes
alignment wastage as being in use, this figure may be greater than
zero even when no user-level chunks are allocated.
The reported current and maximum system memory can be inaccurate if
a program makes other calls to system memory allocation functions
(normally sbrk) outside of malloc.
malloc_stats prints only the most commonly interesting statistics.
More information can be obtained by calling mallinfo.
*/
void __malloc_stats(void);
/*
posix_memalign(void **memptr, size_t alignment, size_t size);
POSIX wrapper like memalign(), checking for validity of size.
*/
int __posix_memalign(void **, size_t, size_t);
/* mallopt tuning options */
/*
M_MXFAST is the maximum request size used for "fastbins", special bins
that hold returned chunks without consolidating their spaces. This
enables future requests for chunks of the same size to be handled
very quickly, but can increase fragmentation, and thus increase the
overall memory footprint of a program.
This malloc manages fastbins very conservatively yet still
efficiently, so fragmentation is rarely a problem for values less
than or equal to the default. The maximum supported value of MXFAST
is 80. You wouldn't want it any higher than this anyway. Fastbins
are designed especially for use with many small structs, objects or
strings -- the default handles structs/objects/arrays with sizes up
to 8 4byte fields, or small strings representing words, tokens,
etc. Using fastbins for larger objects normally worsens
fragmentation without improving speed.
M_MXFAST is set in REQUEST size units. It is internally used in
chunksize units, which adds padding and alignment. You can reduce
M_MXFAST to 0 to disable all use of fastbins. This causes the malloc
algorithm to be a closer approximation of fifo-best-fit in all cases,
not just for larger requests, but will generally cause it to be
slower.
*/
/* M_MXFAST is a standard SVID/XPG tuning option, usually listed in malloc.h */
#ifndef M_MXFAST
#define M_MXFAST 1
#endif
#ifndef DEFAULT_MXFAST
#define DEFAULT_MXFAST (64 * SIZE_SZ / 4)
#endif
/*
M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
to keep before releasing via malloc_trim in free().
Automatic trimming is mainly useful in long-lived programs.
Because trimming via sbrk can be slow on some systems, and can
sometimes be wasteful (in cases where programs immediately
afterward allocate more large chunks) the value should be high
enough so that your overall system performance would improve by
releasing this much memory.
The trim threshold and the mmap control parameters (see below)
can be traded off with one another. Trimming and mmapping are
two different ways of releasing unused memory back to the
system. Between these two, it is often possible to keep
system-level demands of a long-lived program down to a bare
minimum. For example, in one test suite of sessions measuring
the XF86 X server on Linux, using a trim threshold of 128K and a
mmap threshold of 192K led to near-minimal long term resource
consumption.
If you are using this malloc in a long-lived program, it should
pay to experiment with these values. As a rough guide, you
might set to a value close to the average size of a process
(program) running on your system. Releasing this much memory
would allow such a process to run in memory. Generally, it's
worth it to tune for trimming rather tham memory mapping when a
program undergoes phases where several large chunks are
allocated and released in ways that can reuse each other's
storage, perhaps mixed with phases where there are no such
chunks at all. And in well-behaved long-lived programs,
controlling release of large blocks via trimming versus mapping
is usually faster.
However, in most programs, these parameters serve mainly as
protection against the system-level effects of carrying around
massive amounts of unneeded memory. Since frequent calls to
sbrk, mmap, and munmap otherwise degrade performance, the default
parameters are set to relatively high values that serve only as
safeguards.
The trim value It must be greater than page size to have any useful
effect. To disable trimming completely, you can set to
(unsigned long)(-1)
Trim settings interact with fastbin (MXFAST) settings: Unless
TRIM_FASTBINS is defined, automatic trimming never takes place upon
freeing a chunk with size less than or equal to MXFAST. Trimming is
instead delayed until subsequent freeing of larger chunks. However,
you can still force an attempted trim by calling malloc_trim.
Also, trimming is not generally possible in cases where
the main arena is obtained via mmap.
Note that the trick some people use of mallocing a huge space and
then freeing it at program startup, in an attempt to reserve system
memory, doesn't have the intended effect under automatic trimming,
since that memory will immediately be returned to the system.
*/
#define M_TRIM_THRESHOLD -1
#ifndef DEFAULT_TRIM_THRESHOLD
#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
#endif
/*
M_TOP_PAD is the amount of extra `padding' space to allocate or
retain whenever sbrk is called. It is used in two ways internally:
* When sbrk is called to extend the top of the arena to satisfy
a new malloc request, this much padding is added to the sbrk
request.
* When malloc_trim is called automatically from free(),
it is used as the `pad' argument.
In both cases, the actual amount of padding is rounded
so that the end of the arena is always a system page boundary.
The main reason for using padding is to avoid calling sbrk so
often. Having even a small pad greatly reduces the likelihood
that nearly every malloc request during program start-up (or
after trimming) will invoke sbrk, which needlessly wastes
time.
Automatic rounding-up to page-size units is normally sufficient
to avoid measurable overhead, so the default is 0. However, in
systems where sbrk is relatively slow, it can pay to increase
this value, at the expense of carrying around more memory than
the program needs.
*/
#define M_TOP_PAD -2
#ifndef DEFAULT_TOP_PAD
#define DEFAULT_TOP_PAD (0)
#endif
/*
MMAP_THRESHOLD_MAX and _MIN are the bounds on the dynamically
adjusted MMAP_THRESHOLD.
*/
#ifndef DEFAULT_MMAP_THRESHOLD_MIN
#define DEFAULT_MMAP_THRESHOLD_MIN (128 * 1024)
#endif
#ifndef DEFAULT_MMAP_THRESHOLD_MAX
/* For 32-bit platforms we cannot increase the maximum mmap
threshold much because it is also the minimum value for the
maximum heap size and its alignment. Going above 512k (i.e., 1M
for new heaps) wastes too much address space. */
# if __WORDSIZE == 32
# define DEFAULT_MMAP_THRESHOLD_MAX (512 * 1024)
# else
# define DEFAULT_MMAP_THRESHOLD_MAX (4 * 1024 * 1024 * sizeof(long))
# endif
#endif
/*
M_MMAP_THRESHOLD is the request size threshold for using mmap()
to service a request. Requests of at least this size that cannot
be allocated using already-existing space will be serviced via mmap.
(If enough normal freed space already exists it is used instead.)
Using mmap segregates relatively large chunks of memory so that
they can be individually obtained and released from the host
system. A request serviced through mmap is never reused by any
other request (at least not directly; the system may just so
happen to remap successive requests to the same locations).
Segregating space in this way has the benefits that:
1. Mmapped space can ALWAYS be individually released back
to the system, which helps keep the system level memory
demands of a long-lived program low.
2. Mapped memory can never become `locked' between
other chunks, as can happen with normally allocated chunks, which
means that even trimming via malloc_trim would not release them.
3. On some systems with "holes" in address spaces, mmap can obtain
memory that sbrk cannot.
However, it has the disadvantages that:
1. The space cannot be reclaimed, consolidated, and then
used to service later requests, as happens with normal chunks.
2. It can lead to more wastage because of mmap page alignment
requirements
3. It causes malloc performance to be more dependent on host
system memory management support routines which may vary in
implementation quality and may impose arbitrary
limitations. Generally, servicing a request via normal
malloc steps is faster than going through a system's mmap.
The advantages of mmap nearly always outweigh disadvantages for
"large" chunks, but the value of "large" varies across systems. The
default is an empirically derived value that works well in most
systems.
Update in 2006:
The above was written in 2001. Since then the world has changed a lot.
Memory got bigger. Applications got bigger. The virtual address space
layout in 32 bit linux changed.
In the new situation, brk() and mmap space is shared and there are no
artificial limits on brk size imposed by the kernel. What is more,
applications have started using transient allocations larger than the
128Kb as was imagined in 2001.
The price for mmap is also high now; each time glibc mmaps from the
kernel, the kernel is forced to zero out the memory it gives to the
application. Zeroing memory is expensive and eats a lot of cache and
memory bandwidth. This has nothing to do with the efficiency of the
virtual memory system, by doing mmap the kernel just has no choice but
to zero.
In 2001, the kernel had a maximum size for brk() which was about 800
megabytes on 32 bit x86, at that point brk() would hit the first
mmaped shared libaries and couldn't expand anymore. With current 2.6
kernels, the VA space layout is different and brk() and mmap
both can span the entire heap at will.
Rather than using a static threshold for the brk/mmap tradeoff,
we are now using a simple dynamic one. The goal is still to avoid
fragmentation. The old goals we kept are
1) try to get the long lived large allocations to use mmap()
2) really large allocations should always use mmap()
and we're adding now:
3) transient allocations should use brk() to avoid forcing the kernel
having to zero memory over and over again
The implementation works with a sliding threshold, which is by default
limited to go between 128Kb and 32Mb (64Mb for 64 bitmachines) and starts
out at 128Kb as per the 2001 default.
This allows us to satisfy requirement 1) under the assumption that long
lived allocations are made early in the process' lifespan, before it has
started doing dynamic allocations of the same size (which will
increase the threshold).
The upperbound on the threshold satisfies requirement 2)
The threshold goes up in value when the application frees memory that was
allocated with the mmap allocator. The idea is that once the application
starts freeing memory of a certain size, it's highly probable that this is
a size the application uses for transient allocations. This estimator
is there to satisfy the new third requirement.
*/
#define M_MMAP_THRESHOLD -3
#ifndef DEFAULT_MMAP_THRESHOLD
#define DEFAULT_MMAP_THRESHOLD DEFAULT_MMAP_THRESHOLD_MIN
#endif
/*
M_MMAP_MAX is the maximum number of requests to simultaneously
service using mmap. This parameter exists because
some systems have a limited number of internal tables for
use by mmap, and using more than a few of them may degrade
performance.
The default is set to a value that serves only as a safeguard.
Setting to 0 disables use of mmap for servicing large requests.
*/
#define M_MMAP_MAX -4
#ifndef DEFAULT_MMAP_MAX
#define DEFAULT_MMAP_MAX (65536)
#endif
#include <malloc.h>
#ifndef RETURN_ADDRESS
#define RETURN_ADDRESS(X_) (NULL)
#endif
/* Forward declarations. */
struct malloc_chunk;
typedef struct malloc_chunk* mchunkptr;
/* Internal routines. */
static void* _int_malloc(mstate, size_t);
static void _int_free(mstate, mchunkptr, int);
static void* _int_realloc(mstate, mchunkptr, INTERNAL_SIZE_T,
INTERNAL_SIZE_T);
static void* _int_memalign(mstate, size_t, size_t);
static void* _mid_memalign(size_t, size_t, void *);
static void malloc_printerr(const char *str) __attribute__ ((noreturn));
static void* mem2mem_check(void *p, size_t sz);
static void top_check(void);
static void munmap_chunk(mchunkptr p);
#if HAVE_MREMAP
static mchunkptr mremap_chunk(mchunkptr p, size_t new_size);
#endif
static void* malloc_check(size_t sz, const void *caller);
static void free_check(void* mem, const void *caller);
static void* realloc_check(void* oldmem, size_t bytes,
const void *caller);
static void* memalign_check(size_t alignment, size_t bytes,
const void *caller);
/* ------------------ MMAP support ------------------ */
#include <fcntl.h>
#include <sys/mman.h>
#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
# define MAP_ANONYMOUS MAP_ANON
#endif
#ifndef MAP_NORESERVE
# define MAP_NORESERVE 0
#endif
#define MMAP(addr, size, prot, flags) \
__mmap((addr), (size), (prot), (flags)|MAP_ANONYMOUS|MAP_PRIVATE, -1, 0)
/*
----------------------- Chunk representations -----------------------
*/
/*
This struct declaration is misleading (but accurate and necessary).
It declares a "view" into memory allowing access to necessary
fields at known offsets from a given base. See explanation below.
*/
struct malloc_chunk {
INTERNAL_SIZE_T mchunk_prev_size; /* Size of previous chunk (if free). */
INTERNAL_SIZE_T mchunk_size; /* Size in bytes, including overhead. */
struct malloc_chunk* fd; /* double links -- used only if free. */
struct malloc_chunk* bk;
/* Only used for large blocks: pointer to next larger size. */
struct malloc_chunk* fd_nextsize; /* double links -- used only if free. */
struct malloc_chunk* bk_nextsize;
};
/*
malloc_chunk details:
(The following includes lightly edited explanations by Colin Plumb.)
Chunks of memory are maintained using a `boundary tag' method as
described in e.g., Knuth or Standish. (See the paper by Paul
Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
survey of such techniques.) Sizes of free chunks are stored both
in the front of each chunk and at the end. This makes
consolidating fragmented chunks into bigger chunks very fast. The
size fields also hold bits representing whether chunks are free or
in use.
An allocated chunk looks like this:
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of previous chunk, if unallocated (P clear) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of chunk, in bytes |A|M|P|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| User data starts here... .
. .
. (malloc_usable_size() bytes) .
. |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (size of chunk, but used for application data) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of next chunk, in bytes |A|0|1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where "chunk" is the front of the chunk for the purpose of most of
the malloc code, but "mem" is the pointer that is returned to the
user. "Nextchunk" is the beginning of the next contiguous chunk.
Chunks always begin on even word boundaries, so the mem portion
(which is returned to the user) is also on an even word boundary, and
thus at least double-word aligned.
Free chunks are stored in circular doubly-linked lists, and look like this:
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of previous chunk, if unallocated (P clear) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
`head:' | Size of chunk, in bytes |A|0|P|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Forward pointer to next chunk in list |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Back pointer to previous chunk in list |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unused space (may be 0 bytes long) .
. .
. |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
`foot:' | Size of chunk, in bytes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Size of next chunk, in bytes |A|0|0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The P (PREV_INUSE) bit, stored in the unused low-order bit of the
chunk size (which is always a multiple of two words), is an in-use
bit for the *previous* chunk. If that bit is *clear*, then the
word before the current chunk size contains the previous chunk
size, and can be used to find the front of the previous chunk.
The very first chunk allocated always has this bit set,
preventing access to non-existent (or non-owned) memory. If
prev_inuse is set for any given chunk, then you CANNOT determine
the size of the previous chunk, and might even get a memory
addressing fault when trying to do so.
The A (NON_MAIN_ARENA) bit is cleared for chunks on the initial,
main arena, described by the main_arena variable. When additional
threads are spawned, each thread receives its own arena (up to a
configurable limit, after which arenas are reused for multiple
threads), and the chunks in these arenas have the A bit set. To
find the arena for a chunk on such a non-main arena, heap_for_ptr
performs a bit mask operation and indirection through the ar_ptr
member of the per-heap header heap_info (see arena.c).
Note that the `foot' of the current chunk is actually represented
as the prev_size of the NEXT chunk. This makes it easier to
deal with alignments etc but can be very confusing when trying
to extend or adapt this code.
The three exceptions to all this are:
1. The special chunk `top' doesn't bother using the
trailing size field since there is no next contiguous chunk
that would have to index off it. After initialization, `top'
is forced to always exist. If it would become less than
MINSIZE bytes long, it is replenished.
2. Chunks allocated via mmap, which have the second-lowest-order
bit M (IS_MMAPPED) set in their size fields. Because they are
allocated one-by-one, each must contain its own trailing size
field. If the M bit is set, the other bits are ignored
(because mmapped chunks are neither in an arena, nor adjacent
to a freed chunk). The M bit is also used for chunks which
originally came from a dumped heap via malloc_set_state in
hooks.c.
3. Chunks in fastbins are treated as allocated chunks from the
point of view of the chunk allocator. They are consolidated
with their neighbors only in bulk, in malloc_consolidate.
*/
/*
---------- Size and alignment checks and conversions ----------
*/
/* conversion from malloc headers to user pointers, and back */
#define chunk2mem(p) ((void*)((char*)(p) + 2*SIZE_SZ))
#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))
/* The smallest possible chunk */
#define MIN_CHUNK_SIZE (offsetof(struct malloc_chunk, fd_nextsize))
/* The smallest size we can malloc is an aligned minimal chunk */
#define MINSIZE \
(unsigned long)(((MIN_CHUNK_SIZE+MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK))
/* Check if m has acceptable alignment */
#define aligned_OK(m) (((unsigned long)(m) & MALLOC_ALIGN_MASK) == 0)
#define misaligned_chunk(p) \
((uintptr_t)(MALLOC_ALIGNMENT == 2 * SIZE_SZ ? (p) : chunk2mem (p)) \
& MALLOC_ALIGN_MASK)
/*
Check if a request is so large that it would wrap around zero when
padded and aligned. To simplify some other code, the bound is made
low enough so that adding MINSIZE will also not wrap around zero.
*/
#define REQUEST_OUT_OF_RANGE(req) \
((unsigned long) (req) >= \
(unsigned long) (INTERNAL_SIZE_T) (-2 * MINSIZE))
/* pad request bytes into a usable size -- internal version */
#define request2size(req) \
(((req) + SIZE_SZ + MALLOC_ALIGN_MASK < MINSIZE) ? \
MINSIZE : \
((req) + SIZE_SZ + MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK)
/* Same, except also perform an argument and result check. First, we check
that the padding done by request2size didn't result in an integer
overflow. Then we check (using REQUEST_OUT_OF_RANGE) that the resulting
size isn't so large that a later alignment would lead to another integer
overflow. */
#define checked_request2size(req, sz) \
({ \
(sz) = request2size (req); \
if (((sz) < (req)) \
|| REQUEST_OUT_OF_RANGE (sz)) \
{ \
__set_errno (ENOMEM); \
return 0; \
} \
})
/*
--------------- Physical chunk operations ---------------
*/
/* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
#define PREV_INUSE 0x1
/* extract inuse bit of previous chunk */
#define prev_inuse(p) ((p)->mchunk_size & PREV_INUSE)
/* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
#define IS_MMAPPED 0x2
/* check for mmap()'ed chunk */
#define chunk_is_mmapped(p) ((p)->mchunk_size & IS_MMAPPED)
/* size field is or'ed with NON_MAIN_ARENA if the chunk was obtained
from a non-main arena. This is only set immediately before handing
the chunk to the user, if necessary. */
#define NON_MAIN_ARENA 0x4
/* Check for chunk from main arena. */
#define chunk_main_arena(p) (((p)->mchunk_size & NON_MAIN_ARENA) == 0)
/* Mark a chunk as not being on the main arena. */
#define set_non_main_arena(p) ((p)->mchunk_size |= NON_MAIN_ARENA)
/*
Bits to mask off when extracting size
Note: IS_MMAPPED is intentionally not masked off from size field in
macros for which mmapped chunks should never be seen. This should
cause helpful core dumps to occur if it is tried by accident by
people extending or adapting this malloc.
*/
#define SIZE_BITS (PREV_INUSE | IS_MMAPPED | NON_MAIN_ARENA)
/* Get size, ignoring use bits */
#define chunksize(p) (chunksize_nomask (p) & ~(SIZE_BITS))
/* Like chunksize, but do not mask SIZE_BITS. */
#define chunksize_nomask(p) ((p)->mchunk_size)
/* Ptr to next physical malloc_chunk. */
#define next_chunk(p) ((mchunkptr) (((char *) (p)) + chunksize (p)))
/* Size of the chunk below P. Only valid if !prev_inuse (P). */
#define prev_size(p) ((p)->mchunk_prev_size)
/* Set the size of the chunk below P. Only valid if !prev_inuse (P). */
#define set_prev_size(p, sz) ((p)->mchunk_prev_size = (sz))
/* Ptr to previous physical malloc_chunk. Only valid if !prev_inuse (P). */
#define prev_chunk(p) ((mchunkptr) (((char *) (p)) - prev_size (p)))
/* Treat space at ptr + offset as a chunk */
#define chunk_at_offset(p, s) ((mchunkptr) (((char *) (p)) + (s)))
/* extract p's inuse bit */
#define inuse(p) \
((((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size) & PREV_INUSE)
/* set/clear chunk as being inuse without otherwise disturbing */
#define set_inuse(p) \
((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size |= PREV_INUSE
#define clear_inuse(p) \
((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size &= ~(PREV_INUSE)
/* check/set/clear inuse bits in known places */
#define inuse_bit_at_offset(p, s) \
(((mchunkptr) (((char *) (p)) + (s)))->mchunk_size & PREV_INUSE)
#define set_inuse_bit_at_offset(p, s) \
(((mchunkptr) (((char *) (p)) + (s)))->mchunk_size |= PREV_INUSE)
#define clear_inuse_bit_at_offset(p, s) \
(((mchunkptr) (((char *) (p)) + (s)))->mchunk_size &= ~(PREV_INUSE))
/* Set size at head, without disturbing its use bit */
#define set_head_size(p, s) ((p)->mchunk_size = (((p)->mchunk_size & SIZE_BITS) | (s)))
/* Set size/use field */
#define set_head(p, s) ((p)->mchunk_size = (s))
/* Set size at footer (only when chunk is not in use) */
#define set_foot(p, s) (((mchunkptr) ((char *) (p) + (s)))->mchunk_prev_size = (s))
#pragma GCC poison mchunk_size
#pragma GCC poison mchunk_prev_size
/*
-------------------- Internal data structures --------------------
All internal state is held in an instance of malloc_state defined
below. There are no other static variables, except in two optional
cases:
* If USE_MALLOC_LOCK is defined, the mALLOC_MUTEx declared above.
* If mmap doesn't support MAP_ANONYMOUS, a dummy file descriptor
for mmap.
Beware of lots of tricks that minimize the total bookkeeping space
requirements. The result is a little over 1K bytes (for 4byte
pointers and size_t.)
*/
/*
Bins
An array of bin headers for free chunks. Each bin is doubly
linked. The bins are approximately proportionally (log) spaced.
There are a lot of these bins (128). This may look excessive, but
works very well in practice. Most bins hold sizes that are
unusual as malloc request sizes, but are more usual for fragments
and consolidated sets of chunks, which is what these bins hold, so
they can be found quickly. All procedures maintain the invariant
that no consolidated chunk physically borders another one, so each
chunk in a list is known to be preceeded and followed by either
inuse chunks or the ends of memory.
Chunks in bins are kept in size order, with ties going to the
approximately least recently used chunk. Ordering isn't needed
for the small bins, which all contain the same-sized chunks, but
facilitates best-fit allocation for larger chunks. These lists
are just sequential. Keeping them in order almost never requires
enough traversal to warrant using fancier ordered data
structures.
Chunks of the same size are linked with the most
recently freed at the front, and allocations are taken from the
back. This results in LRU (FIFO) allocation order, which tends
to give each chunk an equal opportunity to be consolidated with
adjacent freed chunks, resulting in larger free chunks and less
fragmentation.
To simplify use in double-linked lists, each bin header acts
as a malloc_chunk. This avoids special-casing for headers.
But to conserve space and improve locality, we allocate
only the fd/bk pointers of bins, and then use repositioning tricks
to treat these as the fields of a malloc_chunk*.
*/
typedef struct malloc_chunk *mbinptr;
/* addressing -- note that bin_at(0) does not exist */
#define bin_at(m, i) \
(mbinptr) (((char *) &((m)->bins[((i) - 1) * 2])) \
- offsetof (struct malloc_chunk, fd))
/* analog of ++bin */
#define next_bin(b) ((mbinptr) ((char *) (b) + (sizeof (mchunkptr) << 1)))
/* Reminders about list directionality within bins */
#define first(b) ((b)->fd)
#define last(b) ((b)->bk)
/*
Indexing
Bins for sizes < 512 bytes contain chunks of all the same size, spaced
8 bytes apart. Larger bins are approximately logarithmically spaced:
64 bins of size 8
32 bins of size 64
16 bins of size 512
8 bins of size 4096
4 bins of size 32768
2 bins of size 262144
1 bin of size what's left
There is actually a little bit of slop in the numbers in bin_index
for the sake of speed. This makes no difference elsewhere.
The bins top out around 1MB because we expect to service large
requests via mmap.
Bin 0 does not exist. Bin 1 is the unordered list; if that would be
a valid chunk size the small bins are bumped up one.
*/
#define NBINS 128
#define NSMALLBINS 64
#define SMALLBIN_WIDTH MALLOC_ALIGNMENT
#define SMALLBIN_CORRECTION (MALLOC_ALIGNMENT > 2 * SIZE_SZ)
#define MIN_LARGE_SIZE ((NSMALLBINS - SMALLBIN_CORRECTION) * SMALLBIN_WIDTH)
#define in_smallbin_range(sz) \
((unsigned long) (sz) < (unsigned long) MIN_LARGE_SIZE)
#define smallbin_index(sz) \
((SMALLBIN_WIDTH == 16 ? (((unsigned) (sz)) >> 4) : (((unsigned) (sz)) >> 3))\
+ SMALLBIN_CORRECTION)
#define largebin_index_32(sz) \
(((((unsigned long) (sz)) >> 6) <= 38) ? 56 + (((unsigned long) (sz)) >> 6) :\
((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
126)
#define largebin_index_32_big(sz) \
(((((unsigned long) (sz)) >> 6) <= 45) ? 49 + (((unsigned long) (sz)) >> 6) :\
((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
126)
// XXX It remains to be seen whether it is good to keep the widths of
// XXX the buckets the same or whether it should be scaled by a factor
// XXX of two as well.
#define largebin_index_64(sz) \
(((((unsigned long) (sz)) >> 6) <= 48) ? 48 + (((unsigned long) (sz)) >> 6) :\
((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
126)
#define largebin_index(sz) \
(SIZE_SZ == 8 ? largebin_index_64 (sz) \
: MALLOC_ALIGNMENT == 16 ? largebin_index_32_big (sz) \
: largebin_index_32 (sz))
#define bin_index(sz) \
((in_smallbin_range (sz)) ? smallbin_index (sz) : largebin_index (sz))
/* Take a chunk off a bin list. */
static void
unlink_chunk (mstate av, mchunkptr p)
{
if (chunksize (p) != prev_size (next_chunk (p)))
malloc_printerr ("corrupted size vs. prev_size");
mchunkptr fd = p->fd;
mchunkptr bk = p->bk;
if (__builtin_expect (fd->bk != p || bk->fd != p, 0))
malloc_printerr ("corrupted double-linked list");
fd->bk = bk;
bk->fd = fd;
if (!in_smallbin_range (chunksize_nomask (p)) && p->fd_nextsize != NULL)
{
if (p->fd_nextsize->bk_nextsize != p
|| p->bk_nextsize->fd_nextsize != p)
malloc_printerr ("corrupted double-linked list (not small)");
if (fd->fd_nextsize == NULL)
{
if (p->fd_nextsize == p)
fd->fd_nextsize = fd->bk_nextsize = fd;
else
{
fd->fd_nextsize = p->fd_nextsize;
fd->bk_nextsize = p->bk_nextsize;
p->fd_nextsize->bk_nextsize = fd;
p->bk_nextsize->fd_nextsize = fd;
}
}
else
{
p->fd_nextsize->bk_nextsize = p->bk_nextsize;
p->bk_nextsize->fd_nextsize = p->fd_nextsize;
}
}
}
/*
Unsorted chunks
All remainders from chunk splits, as well as all returned chunks,
are first placed in the "unsorted" bin. They are then placed
in regular bins after malloc gives them ONE chance to be used before
binning. So, basically, the unsorted_chunks list acts as a queue,
with chunks being placed on it in free (and malloc_consolidate),
and taken off (to be either used or placed in bins) in malloc.
The NON_MAIN_ARENA flag is never set for unsorted chunks, so it
does not have to be taken into account in size comparisons.
*/
/* The otherwise unindexable 1-bin is used to hold unsorted chunks. */
#define unsorted_chunks(M) (bin_at (M, 1))
/*
Top
The top-most available chunk (i.e., the one bordering the end of
available memory) is treated specially. It is never included in
any bin, is used only if no other chunk is available, and is
released back to the system if it is very large (see
M_TRIM_THRESHOLD). Because top initially
points to its own bin with initial zero size, thus forcing
extension on the first malloc request, we avoid having any special
code in malloc to check whether it even exists yet. But we still
need to do so when getting memory from system, so we make
initial_top treat the bin as a legal but unusable chunk during the
interval between initialization and the first call to
sysmalloc. (This is somewhat delicate, since it relies on
the 2 preceding words to be zero during this interval as well.)
*/
/* Conveniently, the unsorted bin can be used as dummy top on first call */
#define initial_top(M) (unsorted_chunks (M))
/*
Binmap
To help compensate for the large number of bins, a one-level index
structure is used for bin-by-bin searching. `binmap' is a
bitvector recording whether bins are definitely empty so they can
be skipped over during during traversals. The bits are NOT always
cleared as soon as bins are empty, but instead only
when they are noticed to be empty during traversal in malloc.
*/
/* Conservatively use 32 bits per map word, even if on 64bit system */
#define BINMAPSHIFT 5
#define BITSPERMAP (1U << BINMAPSHIFT)
#define BINMAPSIZE (NBINS / BITSPERMAP)
#define idx2block(i) ((i) >> BINMAPSHIFT)
#define idx2bit(i) ((1U << ((i) & ((1U << BINMAPSHIFT) - 1))))
#define mark_bin(m, i) ((m)->binmap[idx2block (i)] |= idx2bit (i))
#define unmark_bin(m, i) ((m)->binmap[idx2block (i)] &= ~(idx2bit (i)))
#define get_binmap(m, i) ((m)->binmap[idx2block (i)] & idx2bit (i))
/*
Fastbins
An array of lists holding recently freed small chunks. Fastbins
are not doubly linked. It is faster to single-link them, and
since chunks are never removed from the middles of these lists,
double linking is not necessary. Also, unlike regular bins, they
are not even processed in FIFO order (they use faster LIFO) since
ordering doesn't much matter in the transient contexts in which
fastbins are normally used.
Chunks in fastbins keep their inuse bit set, so they cannot
be consolidated with other free chunks. malloc_consolidate
releases all chunks in fastbins and consolidates them with
other free chunks.
*/
typedef struct malloc_chunk *mfastbinptr;
#define fastbin(ar_ptr, idx) ((ar_ptr)->fastbinsY[idx])
/* offset 2 to use otherwise unindexable first 2 bins */
#define fastbin_index(sz) \
((((unsigned int) (sz)) >> (SIZE_SZ == 8 ? 4 : 3)) - 2)
/* The maximum fastbin request size we support */
#define MAX_FAST_SIZE (80 * SIZE_SZ / 4)
#define NFASTBINS (fastbin_index (request2size (MAX_FAST_SIZE)) + 1)
/*
FASTBIN_CONSOLIDATION_THRESHOLD is the size of a chunk in free()
that triggers automatic consolidation of possibly-surrounding
fastbin chunks. This is a heuristic, so the exact value should not
matter too much. It is defined at half the default trim threshold as a
compromise heuristic to only attempt consolidation if it is likely
to lead to trimming. However, it is not dynamically tunable, since
consolidation reduces fragmentation surrounding large chunks even
if trimming is not used.
*/
#define FASTBIN_CONSOLIDATION_THRESHOLD (65536UL)
/*
NONCONTIGUOUS_BIT indicates that MORECORE does not return contiguous
regions. Otherwise, contiguity is exploited in merging together,
when possible, results from consecutive MORECORE calls.
The initial value comes from MORECORE_CONTIGUOUS, but is
changed dynamically if mmap is ever used as an sbrk substitute.
*/
#define NONCONTIGUOUS_BIT (2U)
#define contiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) == 0)
#define noncontiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) != 0)
#define set_noncontiguous(M) ((M)->flags |= NONCONTIGUOUS_BIT)
#define set_contiguous(M) ((M)->flags &= ~NONCONTIGUOUS_BIT)
/* Maximum size of memory handled in fastbins. */
static INTERNAL_SIZE_T global_max_fast;
/*
Set value of max_fast.
Use impossibly small value if 0.
Precondition: there are no existing fastbin chunks in the main arena.
Since do_check_malloc_state () checks this, we call malloc_consolidate ()
before changing max_fast. Note other arenas will leak their fast bin
entries if max_fast is reduced.
*/
#define set_max_fast(s) \
global_max_fast = (((s) == 0) \
? SMALLBIN_WIDTH : ((s + SIZE_SZ) & ~MALLOC_ALIGN_MASK))
static inline INTERNAL_SIZE_T
get_max_fast (void)
{
/* Tell the GCC optimizers that global_max_fast is never larger
than MAX_FAST_SIZE. This avoids out-of-bounds array accesses in
_int_malloc after constant propagation of the size parameter.
(The code never executes because malloc preserves the
global_max_fast invariant, but the optimizers may not recognize
this.) */
if (global_max_fast > MAX_FAST_SIZE)
__builtin_unreachable ();
return global_max_fast;
}
/*
----------- Internal state representation and initialization -----------
*/
/*
have_fastchunks indicates that there are probably some fastbin chunks.
It is set true on entering a chunk into any fastbin, and cleared early in
malloc_consolidate. The value is approximate since it may be set when there
are no fastbin chunks, or it may be clear even if there are fastbin chunks
available. Given it's sole purpose is to reduce number of redundant calls to
malloc_consolidate, it does not affect correctness. As a result we can safely
use relaxed atomic accesses.
*/
struct malloc_state
{
/* Serialize access. */
__libc_lock_define (, mutex);
/* Flags (formerly in max_fast). */
int flags;
/* Set if the fastbin chunks contain recently inserted free blocks. */
/* Note this is a bool but not all targets support atomics on booleans. */
int have_fastchunks;
/* Fastbins */
mfastbinptr fastbinsY[NFASTBINS];
/* Base of the topmost chunk -- not otherwise kept in a bin */
mchunkptr top;
/* The remainder from the most recent split of a small request */
mchunkptr last_remainder;
/* Normal bins packed as described above */
mchunkptr bins[NBINS * 2 - 2];
/* Bitmap of bins */
unsigned int binmap[BINMAPSIZE];
/* Linked list */
struct malloc_state *next;
/* Linked list for free arenas. Access to this field is serialized
by free_list_lock in arena.c. */
struct malloc_state *next_free;
/* Number of threads attached to this arena. 0 if the arena is on
the free list. Access to this field is serialized by
free_list_lock in arena.c. */
INTERNAL_SIZE_T attached_threads;
/* Memory allocated from the system in this arena. */
INTERNAL_SIZE_T system_mem;
INTERNAL_SIZE_T max_system_mem;
};
struct malloc_par
{
/* Tunable parameters */
unsigned long trim_threshold;
INTERNAL_SIZE_T top_pad;
INTERNAL_SIZE_T mmap_threshold;
INTERNAL_SIZE_T arena_test;
INTERNAL_SIZE_T arena_max;
/* Memory map support */
int n_mmaps;
int n_mmaps_max;
int max_n_mmaps;
/* the mmap_threshold is dynamic, until the user sets
it manually, at which point we need to disable any
dynamic behavior. */
int no_dyn_threshold;
/* Statistics */
INTERNAL_SIZE_T mmapped_mem;
INTERNAL_SIZE_T max_mmapped_mem;
/* First address handed out by MORECORE/sbrk. */
char *sbrk_base;
#if USE_TCACHE
/* Maximum number of buckets to use. */
size_t tcache_bins;
size_t tcache_max_bytes;
/* Maximum number of chunks in each bucket. */
size_t tcache_count;
/* Maximum number of chunks to remove from the unsorted list, which
aren't used to prefill the cache. */
size_t tcache_unsorted_limit;
#endif
};
/* There are several instances of this struct ("arenas") in this
malloc. If you are adapting this malloc in a way that does NOT use
a static or mmapped malloc_state, you MUST explicitly zero-fill it
before using. This malloc relies on the property that malloc_state
is initialized to all zeroes (as is true of C statics). */
static struct malloc_state main_arena =
{
.mutex = _LIBC_LOCK_INITIALIZER,
.next = &main_arena,
.attached_threads = 1
};
/* These variables are used for undumping support. Chunked are marked
as using mmap, but we leave them alone if they fall into this
range. NB: The chunk size for these chunks only includes the
initial size field (of SIZE_SZ bytes), there is no trailing size
field (unlike with regular mmapped chunks). */
static mchunkptr dumped_main_arena_start; /* Inclusive. */
static mchunkptr dumped_main_arena_end; /* Exclusive. */
/* True if the pointer falls into the dumped arena. Use this after
chunk_is_mmapped indicates a chunk is mmapped. */
#define DUMPED_MAIN_ARENA_CHUNK(p) \
((p) >= dumped_main_arena_start && (p) < dumped_main_arena_end)
/* There is only one instance of the malloc parameters. */
static struct malloc_par mp_ =
{
.top_pad = DEFAULT_TOP_PAD,
.n_mmaps_max = DEFAULT_MMAP_MAX,
.mmap_threshold = DEFAULT_MMAP_THRESHOLD,
.trim_threshold = DEFAULT_TRIM_THRESHOLD,
#define NARENAS_FROM_NCORES(n) ((n) * (sizeof (long) == 4 ? 2 : 8))
.arena_test = NARENAS_FROM_NCORES (1)
#if USE_TCACHE
,
.tcache_count = TCACHE_FILL_COUNT,
.tcache_bins = TCACHE_MAX_BINS,
.tcache_max_bytes = tidx2usize (TCACHE_MAX_BINS-1),
.tcache_unsorted_limit = 0 /* No limit. */
#endif
};
/*
Initialize a malloc_state struct.
This is called from ptmalloc_init () or from _int_new_arena ()
when creating a new arena.
*/
static void
malloc_init_state (mstate av)
{
int i;
mbinptr bin;
/* Establish circular links for normal bins */
for (i = 1; i < NBINS; ++i)
{
bin = bin_at (av, i);
bin->fd = bin->bk = bin;
}
#if MORECORE_CONTIGUOUS
if (av != &main_arena)
#endif
set_noncontiguous (av);
if (av == &main_arena)
set_max_fast (DEFAULT_MXFAST);
atomic_store_relaxed (&av->have_fastchunks, false);
av->top = initial_top (av);
}
/*
Other internal utilities operating on mstates
*/
static void *sysmalloc (INTERNAL_SIZE_T, mstate);
static int systrim (size_t, mstate);
static void malloc_consolidate (mstate);
/* -------------- Early definitions for debugging hooks ---------------- */
/* Define and initialize the hook variables. These weak definitions must
appear before any use of the variables in a function (arena.c uses one). */
#ifndef weak_variable
/* In GNU libc we want the hook variables to be weak definitions to
avoid a problem with Emacs. */
# define weak_variable weak_function
#endif
/* Forward declarations. */
static void *malloc_hook_ini (size_t sz,
const void *caller) __THROW;
static void *realloc_hook_ini (void *ptr, size_t sz,
const void *caller) __THROW;
static void *memalign_hook_ini (size_t alignment, size_t sz,
const void *caller) __THROW;
#if HAVE_MALLOC_INIT_HOOK
void weak_variable (*__malloc_initialize_hook) (void) = NULL;
compat_symbol (libc, __malloc_initialize_hook,
__malloc_initialize_hook, GLIBC_2_0);
#endif
void weak_variable (*__free_hook) (void *__ptr,
const void *) = NULL;
void *weak_variable (*__malloc_hook)
(size_t __size, const void *) = malloc_hook_ini;
void *weak_variable (*__realloc_hook)
(void *__ptr, size_t __size, const void *)
= realloc_hook_ini;
void *weak_variable (*__memalign_hook)
(size_t __alignment, size_t __size, const void *)
= memalign_hook_ini;
void weak_variable (*__after_morecore_hook) (void) = NULL;
/* This function is called from the arena shutdown hook, to free the
thread cache (if it exists). */
static void tcache_thread_shutdown (void);
/* ------------------ Testing support ----------------------------------*/
static int perturb_byte;
static void
alloc_perturb (char *p, size_t n)
{
if (__glibc_unlikely (perturb_byte))
memset (p, perturb_byte ^ 0xff, n);
}
static void
free_perturb (char *p, size_t n)
{
if (__glibc_unlikely (perturb_byte))
memset (p, perturb_byte, n);
}
#include <stap-probe.h>
/* ------------------- Support for multiple arenas -------------------- */
#include "arena.c"
/*
Debugging support
These routines make a number of assertions about the states
of data structures that should be true at all times. If any
are not true, it's very likely that a user program has somehow
trashed memory. (It's also possible that there is a coding error
in malloc. In which case, please report it!)
*/
#if !MALLOC_DEBUG
# define check_chunk(A, P)
# define check_free_chunk(A, P)
# define check_inuse_chunk(A, P)
# define check_remalloced_chunk(A, P, N)
# define check_malloced_chunk(A, P, N)
# define check_malloc_state(A)
#else
# define check_chunk(A, P) do_check_chunk (A, P)
# define check_free_chunk(A, P) do_check_free_chunk (A, P)
# define check_inuse_chunk(A, P) do_check_inuse_chunk (A, P)
# define check_remalloced_chunk(A, P, N) do_check_remalloced_chunk (A, P, N)
# define check_malloced_chunk(A, P, N) do_check_malloced_chunk (A, P, N)
# define check_malloc_state(A) do_check_malloc_state (A)
/*
Properties of all chunks
*/
static void
do_check_chunk (mstate av, mchunkptr p)
{
unsigned long sz = chunksize (p);
/* min and max possible addresses assuming contiguous allocation */
char *max_address = (char *) (av->top) + chunksize (av->top);
char *min_address = max_address - av->system_mem;
if (!chunk_is_mmapped (p))
{
/* Has legal address ... */
if (p != av->top)
{
if (contiguous (av))
{
assert (((char *) p) >= min_address);
assert (((char *) p + sz) <= ((char *) (av->top)));
}
}
else
{
/* top size is always at least MINSIZE */
assert ((unsigned long) (sz) >= MINSIZE);
/* top predecessor always marked inuse */
assert (prev_inuse (p));
}
}
else if (!DUMPED_MAIN_ARENA_CHUNK (p))
{
/* address is outside main heap */
if (contiguous (av) && av->top != initial_top (av))
{
assert (((char *) p) < min_address || ((char *) p) >= max_address);
}
/* chunk is page-aligned */
assert (((prev_size (p) + sz) & (GLRO (dl_pagesize) - 1)) == 0);
/* mem is aligned */
assert (aligned_OK (chunk2mem (p)));
}
}
/*
Properties of free chunks
*/
static void
do_check_free_chunk (mstate av, mchunkptr p)
{
INTERNAL_SIZE_T sz = chunksize_nomask (p) & ~(PREV_INUSE | NON_MAIN_ARENA);
mchunkptr next = chunk_at_offset (p, sz);
do_check_chunk (av, p);
/* Chunk must claim to be free ... */
assert (!inuse (p));
assert (!chunk_is_mmapped (p));
/* Unless a special marker, must have OK fields */
if ((unsigned long) (sz) >= MINSIZE)
{
assert ((sz & MALLOC_ALIGN_MASK) == 0);
assert (aligned_OK (chunk2mem (p)));
/* ... matching footer field */
assert (prev_size (next_chunk (p)) == sz);
/* ... and is fully consolidated */
assert (prev_inuse (p));
assert (next == av->top || inuse (next));
/* ... and has minimally sane links */
assert (p->fd->bk == p);
assert (p->bk->fd == p);
}
else /* markers are always of size SIZE_SZ */
assert (sz == SIZE_SZ);
}
/*
Properties of inuse chunks
*/
static void
do_check_inuse_chunk (mstate av, mchunkptr p)
{
mchunkptr next;
do_check_chunk (av, p);
if (chunk_is_mmapped (p))
return; /* mmapped chunks have no next/prev */
/* Check whether it claims to be in use ... */
assert (inuse (p));
next = next_chunk (p);
/* ... and is surrounded by OK chunks.
Since more things can be checked with free chunks than inuse ones,
if an inuse chunk borders them and debug is on, it's worth doing them.
*/
if (!prev_inuse (p))
{
/* Note that we cannot even look at prev unless it is not inuse */
mchunkptr prv = prev_chunk (p);
assert (next_chunk (prv) == p);
do_check_free_chunk (av, prv);
}
if (next == av->top)
{
assert (prev_inuse (next));
assert (chunksize (next) >= MINSIZE);
}
else if (!inuse (next))
do_check_free_chunk (av, next);
}
/*
Properties of chunks recycled from fastbins
*/
static void
do_check_remalloced_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T s)
{
INTERNAL_SIZE_T sz = chunksize_nomask (p) & ~(PREV_INUSE | NON_MAIN_ARENA);
if (!chunk_is_mmapped (p))
{
assert (av == arena_for_chunk (p));
if (chunk_main_arena (p))
assert (av == &main_arena);
else
assert (av != &main_arena);
}
do_check_inuse_chunk (av, p);
/* Legal size ... */
assert ((sz & MALLOC_ALIGN_MASK) == 0);
assert ((unsigned long) (sz) >= MINSIZE);
/* ... and alignment */
assert (aligned_OK (chunk2mem (p)));
/* chunk is less than MINSIZE more than request */
assert ((long) (sz) - (long) (s) >= 0);
assert ((long) (sz) - (long) (s + MINSIZE) < 0);
}
/*
Properties of nonrecycled chunks at the point they are malloced
*/
static void
do_check_malloced_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T s)
{
/* same as recycled case ... */
do_check_remalloced_chunk (av, p, s);
/*
... plus, must obey implementation invariant that prev_inuse is
always true of any allocated chunk; i.e., that each allocated
chunk borders either a previously allocated and still in-use
chunk, or the base of its memory arena. This is ensured
by making all allocations from the `lowest' part of any found
chunk. This does not necessarily hold however for chunks
recycled via fastbins.
*/
assert (prev_inuse (p));
}
/*
Properties of malloc_state.
This may be useful for debugging malloc, as well as detecting user
programmer errors that somehow write into malloc_state.
If you are extending or experimenting with this malloc, you can
probably figure out how to hack this routine to print out or
display chunk addresses, sizes, bins, and other instrumentation.
*/
static void
do_check_malloc_state (mstate av)
{
int i;
mchunkptr p;
mchunkptr q;
mbinptr b;
unsigned int idx;
INTERNAL_SIZE_T size;
unsigned long total = 0;
int max_fast_bin;
/* internal size_t must be no wider than pointer type */
assert (sizeof (INTERNAL_SIZE_T) <= sizeof (char *));
/* alignment is a power of 2 */
assert ((MALLOC_ALIGNMENT & (MALLOC_ALIGNMENT - 1)) == 0);
/* Check the arena is initialized. */
assert (av->top != 0);
/* No memory has been allocated yet, so doing more tests is not possible. */
if (av->top == initial_top (av))
return;
/* pagesize is a power of 2 */
assert (powerof2(GLRO (dl_pagesize)));
/* A contiguous main_arena is consistent with sbrk_base. */
if (av == &main_arena && contiguous (av))
assert ((char *) mp_.sbrk_base + av->system_mem ==
(char *) av->top + chunksize (av->top));
/* properties of fastbins */
/* max_fast is in allowed range */
assert ((get_max_fast () & ~1) <= request2size (MAX_FAST_SIZE));
max_fast_bin = fastbin_index (get_max_fast ());
for (i = 0; i < NFASTBINS; ++i)
{
p = fastbin (av, i);
/* The following test can only be performed for the main arena.
While mallopt calls malloc_consolidate to get rid of all fast
bins (especially those larger than the new maximum) this does
only happen for the main arena. Trying to do this for any
other arena would mean those arenas have to be locked and
malloc_consolidate be called for them. This is excessive. And
even if this is acceptable to somebody it still cannot solve
the problem completely since if the arena is locked a
concurrent malloc call might create a new arena which then
could use the newly invalid fast bins. */
/* all bins past max_fast are empty */
if (av == &main_arena && i > max_fast_bin)
assert (p == 0);
while (p != 0)
{
/* each chunk claims to be inuse */
do_check_inuse_chunk (av, p);
total += chunksize (p);
/* chunk belongs in this bin */
assert (fastbin_index (chunksize (p)) == i);
p = p->fd;
}
}
/* check normal bins */
for (i = 1; i < NBINS; ++i)
{
b = bin_at (av, i);
/* binmap is accurate (except for bin 1 == unsorted_chunks) */
if (i >= 2)
{
unsigned int binbit = get_binmap (av, i);
int empty = last (b) == b;
if (!binbit)
assert (empty);
else if (!empty)
assert (binbit);
}
for (p = last (b); p != b; p = p->bk)
{
/* each chunk claims to be free */
do_check_free_chunk (av, p);
size = chunksize (p);
total += size;
if (i >= 2)
{
/* chunk belongs in bin */
idx = bin_index (size);
assert (idx == i);
/* lists are sorted */
assert (p->bk == b ||
(unsigned long) chunksize (p->bk) >= (unsigned long) chunksize (p));
if (!in_smallbin_range (size))
{
if (p->fd_nextsize != NULL)
{
if (p->fd_nextsize == p)
assert (p->bk_nextsize == p);
else
{
if (p->fd_nextsize == first (b))
assert (chunksize (p) < chunksize (p->fd_nextsize));
else
assert (chunksize (p) > chunksize (p->fd_nextsize));
if (p == first (b))
assert (chunksize (p) > chunksize (p->bk_nextsize));
else
assert (chunksize (p) < chunksize (p->bk_nextsize));
}
}
else
assert (p->bk_nextsize == NULL);
}
}
else if (!in_smallbin_range (size))
assert (p->fd_nextsize == NULL && p->bk_nextsize == NULL);
/* chunk is followed by a legal chain of inuse chunks */
for (q = next_chunk (p);
(q != av->top && inuse (q) &&
(unsigned long) (chunksize (q)) >= MINSIZE);
q = next_chunk (q))
do_check_inuse_chunk (av, q);
}
}
/* top chunk is OK */
check_chunk (av, av->top);
}
#endif
/* ----------------- Support for debugging hooks -------------------- */
#include "hooks.c"
/* ----------- Routines dealing with system allocation -------------- */
/*
sysmalloc handles malloc cases requiring more memory from the system.
On entry, it is assumed that av->top does not have enough
space to service request for nb bytes, thus requiring that av->top
be extended or replaced.
*/
static void *
sysmalloc (INTERNAL_SIZE_T nb, mstate av)
{
mchunkptr old_top; /* incoming value of av->top */
INTERNAL_SIZE_T old_size; /* its size */
char *old_end; /* its end address */
long size; /* arg to first MORECORE or mmap call */
char *brk; /* return value from MORECORE */
long correction; /* arg to 2nd MORECORE call */
char *snd_brk; /* 2nd return val */
INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of new space */
INTERNAL_SIZE_T end_misalign; /* partial page left at end of new space */
char *aligned_brk; /* aligned offset into brk */
mchunkptr p; /* the allocated/returned chunk */
mchunkptr remainder; /* remainder from allocation */
unsigned long remainder_size; /* its size */
size_t pagesize = GLRO (dl_pagesize);
bool tried_mmap = false;
/*
If have mmap, and the request size meets the mmap threshold, and
the system supports mmap, and there are few enough currently
allocated mmapped regions, try to directly map this request
rather than expanding top.
*/
if (av == NULL
|| ((unsigned long) (nb) >= (unsigned long) (mp_.mmap_threshold)
&& (mp_.n_mmaps < mp_.n_mmaps_max)))
{
char *mm; /* return value from mmap call*/
try_mmap:
/*
Round up size to nearest page. For mmapped chunks, the overhead
is one SIZE_SZ unit larger than for normal chunks, because there
is no following chunk whose prev_size field could be used.
See the front_misalign handling below, for glibc there is no
need for further alignments unless we have have high alignment.
*/
if (MALLOC_ALIGNMENT == 2 * SIZE_SZ)
size = ALIGN_UP (nb + SIZE_SZ, pagesize);
else
size = ALIGN_UP (nb + SIZE_SZ + MALLOC_ALIGN_MASK, pagesize);
tried_mmap = true;
/* Don't try if size wraps around 0 */
if ((unsigned long) (size) > (unsigned long) (nb))
{
mm = (char *) (MMAP (0, size, PROT_READ | PROT_WRITE, 0));
if (mm != MAP_FAILED)
{
/*
The offset to the start of the mmapped region is stored
in the prev_size field of the chunk. This allows us to adjust
returned start address to meet alignment requirements here
and in memalign(), and still be able to compute proper
address argument for later munmap in free() and realloc().
*/
if (MALLOC_ALIGNMENT == 2 * SIZE_SZ)
{
/* For glibc, chunk2mem increases the address by 2*SIZE_SZ and
MALLOC_ALIGN_MASK is 2*SIZE_SZ-1. Each mmap'ed area is page
aligned and therefore definitely MALLOC_ALIGN_MASK-aligned. */
assert (((INTERNAL_SIZE_T) chunk2mem (mm) & MALLOC_ALIGN_MASK) == 0);
front_misalign = 0;
}
else
front_misalign = (INTERNAL_SIZE_T) chunk2mem (mm) & MALLOC_ALIGN_MASK;
if (front_misalign > 0)
{
correction = MALLOC_ALIGNMENT - front_misalign;
p = (mchunkptr) (mm + correction);
set_prev_size (p, correction);
set_head (p, (size - correction) | IS_MMAPPED);
}
else
{
p = (mchunkptr) mm;
set_prev_size (p, 0);
set_head (p, size | IS_MMAPPED);
}
/* update statistics */
int new = atomic_exchange_and_add (&mp_.n_mmaps, 1) + 1;
atomic_max (&mp_.max_n_mmaps, new);
unsigned long sum;
sum = atomic_exchange_and_add (&mp_.mmapped_mem, size) + size;
atomic_max (&mp_.max_mmapped_mem, sum);
check_chunk (av, p);
return chunk2mem (p);
}
}
}
/* There are no usable arenas and mmap also failed. */
if (av == NULL)
return 0;
/* Record incoming configuration of top */
old_top = av->top;
old_size = chunksize (old_top);
old_end = (char *) (chunk_at_offset (old_top, old_size));
brk = snd_brk = (char *) (MORECORE_FAILURE);
/*
If not the first time through, we require old_size to be
at least MINSIZE and to have prev_inuse set.
*/
assert ((old_top == initial_top (av) && old_size == 0) ||
((unsigned long) (old_size) >= MINSIZE &&
prev_inuse (old_top) &&
((unsigned long) old_end & (pagesize - 1)) == 0));
/* Precondition: not enough current space to satisfy nb request */
assert ((unsigned long) (old_size) < (unsigned long) (nb + MINSIZE));
if (av != &main_arena)
{
heap_info *old_heap, *heap;
size_t old_heap_size;
/* First try to extend the current heap. */
old_heap = heap_for_ptr (old_top);
old_heap_size = old_heap->size;
if ((long) (MINSIZE + nb - old_size) > 0
&& grow_heap (old_heap, MINSIZE + nb - old_size) == 0)
{
av->system_mem += old_heap->size - old_heap_size;
set_head (old_top, (((char *) old_heap + old_heap->size) - (char *) old_top)
| PREV_INUSE);
}
else if ((heap = new_heap (nb + (MINSIZE + sizeof (*heap)), mp_.top_pad)))
{
/* Use a newly allocated heap. */
heap->ar_ptr = av;
heap->prev = old_heap;
av->system_mem += heap->size;
/* Set up the new top. */
top (av) = chunk_at_offset (heap, sizeof (*heap));
set_head (top (av), (heap->size - sizeof (*heap)) | PREV_INUSE);
/* Setup fencepost and free the old top chunk with a multiple of
MALLOC_ALIGNMENT in size. */
/* The fencepost takes at least MINSIZE bytes, because it might
become the top chunk again later. Note that a footer is set
up, too, although the chunk is marked in use. */
old_size = (old_size - MINSIZE) & ~MALLOC_ALIGN_MASK;
set_head (chunk_at_offset (old_top, old_size + 2 * SIZE_SZ), 0 | PREV_INUSE);
if (old_size >= MINSIZE)
{
set_head (chunk_at_offset (old_top, old_size), (2 * SIZE_SZ) | PREV_INUSE);
set_foot (chunk_at_offset (old_top, old_size), (2 * SIZE_SZ));
set_head (old_top, old_size | PREV_INUSE | NON_MAIN_ARENA);
_int_free (av, old_top, 1);
}
else
{
set_head (old_top, (old_size + 2 * SIZE_SZ) | PREV_INUSE);
set_foot (old_top, (old_size + 2 * SIZE_SZ));
}
}
else if (!tried_mmap)
/* We can at least try to use to mmap memory. */
goto try_mmap;
}
else /* av == main_arena */
{ /* Request enough space for nb + pad + overhead */
size = nb + mp_.top_pad + MINSIZE;
/*
If contiguous, we can subtract out existing space that we hope to
combine with new space. We add it back later only if
we don't actually get contiguous space.
*/
if (contiguous (av))
size -= old_size;
/*
Round to a multiple of page size.
If MORECORE is not contiguous, this ensures that we only call it
with whole-page arguments. And if MORECORE is contiguous and
this is not first time through, this preserves page-alignment of
previous calls. Otherwise, we correct to page-align below.
*/
size = ALIGN_UP (size, pagesize);
/*
Don't try to call MORECORE if argument is so big as to appear
negative. Note that since mmap takes size_t arg, it may succeed
below even if we cannot call MORECORE.
*/
if (size > 0)
{
brk = (char *) (MORECORE (size));
LIBC_PROBE (memory_sbrk_more, 2, brk, size);
}
if (brk != (char *) (MORECORE_FAILURE))
{
/* Call the `morecore' hook if necessary. */
void (*hook) (void) = atomic_forced_read (__after_morecore_hook);
if (__builtin_expect (hook != NULL, 0))
(*hook)();
}
else
{
/*
If have mmap, try using it as a backup when MORECORE fails or
cannot be used. This is worth doing on systems that have "holes" in
address space, so sbrk cannot extend to give contiguous space, but
space is available elsewhere. Note that we ignore mmap max count
and threshold limits, since the space will not be used as a
segregated mmap region.
*/
/* Cannot merge with old top, so add its size back in */
if (contiguous (av))
size = ALIGN_UP (size + old_size, pagesize);
/* If we are relying on mmap as backup, then use larger units */
if ((unsigned long) (size) < (unsigned long) (MMAP_AS_MORECORE_SIZE))
size = MMAP_AS_MORECORE_SIZE;
/* Don't try if size wraps around 0 */
if ((unsigned long) (size) > (unsigned long) (nb))
{
char *mbrk = (char *) (MMAP (0, size, PROT_READ | PROT_WRITE, 0));
if (mbrk != MAP_FAILED)
{
/* We do not need, and cannot use, another sbrk call to find end */
brk = mbrk;
snd_brk = brk + size;
/*
Record that we no longer have a contiguous sbrk region.
After the first time mmap is used as backup, we do not
ever rely on contiguous space since this could incorrectly
bridge regions.
*/
set_noncontiguous (av);
}
}
}
if (brk != (char *) (MORECORE_FAILURE))
{
if (mp_.sbrk_base == 0)
mp_.sbrk_base = brk;
av->system_mem += size;
/*
If MORECORE extends previous space, we can likewise extend top size.
*/
if (brk == old_end && snd_brk == (char *) (MORECORE_FAILURE))
set_head (old_top, (size + old_size) | PREV_INUSE);
else if (contiguous (av) && old_size && brk < old_end)
/* Oops! Someone else killed our space.. Can't touch anything. */
malloc_printerr ("break adjusted to free malloc space");
/*
Otherwise, make adjustments:
* If the first time through or noncontiguous, we need to call sbrk
just to find out where the end of memory lies.
* We need to ensure that all returned chunks from malloc will meet
MALLOC_ALIGNMENT
* If there was an intervening foreign sbrk, we need to adjust sbrk
request size to account for fact that we will not be able to
combine new space with existing space in old_top.
* Almost all systems internally allocate whole pages at a time, in
which case we might as well use the whole last page of request.
So we allocate enough more memory to hit a page boundary now,
which in turn causes future contiguous calls to page-align.
*/
else
{
front_misalign = 0;
end_misalign = 0;
correction = 0;
aligned_brk = brk;
/* handle contiguous cases */
if (contiguous (av))
{
/* Count foreign sbrk as system_mem. */
if (old_size)
av->system_mem += brk - old_end;
/* Guarantee alignment of first new chunk made from this space */
front_misalign = (INTERNAL_SIZE_T) chunk2mem (brk) & MALLOC_ALIGN_MASK;
if (front_misalign > 0)
{
/*
Skip over some bytes to arrive at an aligned position.
We don't need to specially mark these wasted front bytes.
They will never be accessed anyway because
prev_inuse of av->top (and any chunk created from its start)
is always true after initialization.
*/
correction = MALLOC_ALIGNMENT - front_misalign;
aligned_brk += correction;
}
/*
If this isn't adjacent to existing space, then we will not
be able to merge with old_top space, so must add to 2nd request.
*/
correction += old_size;
/* Extend the end address to hit a page boundary */
end_misalign = (INTERNAL_SIZE_T) (brk + size + correction);
correction += (ALIGN_UP (end_misalign, pagesize)) - end_misalign;
assert (correction >= 0);
snd_brk = (char *) (MORECORE (correction));
/*
If can't allocate correction, try to at least find out current
brk. It might be enough to proceed without failing.
Note that if second sbrk did NOT fail, we assume that space
is contiguous with first sbrk. This is a safe assumption unless
program is multithreaded but doesn't use locks and a foreign sbrk
occurred between our first and second calls.
*/
if (snd_brk == (char *) (MORECORE_FAILURE))
{
correction = 0;
snd_brk = (char *) (MORECORE (0));
}
else
{
/* Call the `morecore' hook if necessary. */
void (*hook) (void) = atomic_forced_read (__after_morecore_hook);
if (__builtin_expect (hook != NULL, 0))
(*hook)();
}
}
/* handle non-contiguous cases */
else
{
if (MALLOC_ALIGNMENT == 2 * SIZE_SZ)
/* MORECORE/mmap must correctly align */
assert (((unsigned long) chunk2mem (brk) & MALLOC_ALIGN_MASK) == 0);
else
{
front_misalign = (INTERNAL_SIZE_T) chunk2mem (brk) & MALLOC_ALIGN_MASK;
if (front_misalign > 0)
{
/*
Skip over some bytes to arrive at an aligned position.
We don't need to specially mark these wasted front bytes.
They will never be accessed anyway because
prev_inuse of av->top (and any chunk created from its start)
is always true after initialization.
*/
aligned_brk += MALLOC_ALIGNMENT - front_misalign;
}
}
/* Find out current end of memory */
if (snd_brk == (char *) (MORECORE_FAILURE))
{
snd_brk = (char *) (MORECORE (0));
}
}
/* Adjust top based on results of second sbrk */
if (snd_brk != (char *) (MORECORE_FAILURE))
{
av->top = (mchunkptr) aligned_brk;
set_head (av->top, (snd_brk - aligned_brk + correction) | PREV_INUSE);
av->system_mem += correction;
/*
If not the first time through, we either have a
gap due to foreign sbrk or a non-contiguous region. Insert a
double fencepost at old_top to prevent consolidation with space
we don't own. These fenceposts are artificial chunks that are
marked as inuse and are in any case too small to use. We need
two to make sizes and alignments work out.
*/
if (old_size != 0)
{
/*
Shrink old_top to insert fenceposts, keeping size a
multiple of MALLOC_ALIGNMENT. We know there is at least
enough space in old_top to do this.
*/
old_size = (old_size - 4 * SIZE_SZ) & ~MALLOC_ALIGN_MASK;
set_head (old_top, old_size | PREV_INUSE);
/*
Note that the following assignments completely overwrite
old_top when old_size was previously MINSIZE. This is
intentional. We need the fencepost, even if old_top otherwise gets
lost.
*/
set_head (chunk_at_offset (old_top, old_size),
(2 * SIZE_SZ) | PREV_INUSE);
set_head (chunk_at_offset (old_top, old_size + 2 * SIZE_SZ),
(2 * SIZE_SZ) | PREV_INUSE);
/* If possible, release the rest. */
if (old_size >= MINSIZE)
{
_int_free (av, old_top, 1);
}
}
}
}
}
} /* if (av != &main_arena) */
if ((unsigned long) av->system_mem > (unsigned long) (av->max_system_mem))
av->max_system_mem = av->system_mem;
check_malloc_state (av);
/* finally, do the allocation */
p = av->top;
size = chunksize (p);
/* check that one of the above allocation paths succeeded */
if ((unsigned long) (size) >= (unsigned long) (nb + MINSIZE))
{
remainder_size = size - nb;
remainder = chunk_at_offset (p, nb);
av->top = remainder;
set_head (p, nb | PREV_INUSE | (av != &main_arena ? NON_MAIN_ARENA : 0));
set_head (remainder, remainder_size | PREV_INUSE);
check_malloced_chunk (av, p, nb);
return chunk2mem (p);
}
/* catch all failure paths */
__set_errno (ENOMEM);
return 0;
}
/*
systrim is an inverse of sorts to sysmalloc. It gives memory back
to the system (via negative arguments to sbrk) if there is unused
memory at the `high' end of the malloc pool. It is called
automatically by free() when top space exceeds the trim
threshold. It is also called by the public malloc_trim routine. It
returns 1 if it actually released any memory, else 0.
*/
static int
systrim (size_t pad, mstate av)
{
long top_size; /* Amount of top-most memory */
long extra; /* Amount to release */
long released; /* Amount actually released */
char *current_brk; /* address returned by pre-check sbrk call */
char *new_brk; /* address returned by post-check sbrk call */
size_t pagesize;
long top_area;
pagesize = GLRO (dl_pagesize);
top_size = chunksize (av->top);
top_area = top_size - MINSIZE - 1;
if (top_area <= pad)
return 0;
/* Release in pagesize units and round down to the nearest page. */
extra = ALIGN_DOWN(top_area - pad, pagesize);
if (extra == 0)
return 0;
/*
Only proceed if end of memory is where we last set it.
This avoids problems if there were foreign sbrk calls.
*/
current_brk = (char *) (MORECORE (0));
if (current_brk == (char *) (av->top) + top_size)
{
/*
Attempt to release memory. We ignore MORECORE return value,
and instead call again to find out where new end of memory is.
This avoids problems if first call releases less than we asked,
of if failure somehow altered brk value. (We could still
encounter problems if it altered brk in some very bad way,
but the only thing we can do is adjust anyway, which will cause
some downstream failure.)
*/
MORECORE (-extra);
/* Call the `morecore' hook if necessary. */
void (*hook) (void) = atomic_forced_read (__after_morecore_hook);
if (__builtin_expect (hook != NULL, 0))
(*hook)();
new_brk = (char *) (MORECORE (0));
LIBC_PROBE (memory_sbrk_less, 2, new_brk, extra);
if (new_brk != (char *) MORECORE_FAILURE)
{
released = (long) (current_brk - new_brk);
if (released != 0)
{
/* Success. Adjust top. */
av->system_mem -= released;
set_head (av->top, (top_size - released) | PREV_INUSE);
check_malloc_state (av);
return 1;
}
}
}
return 0;
}
static void
munmap_chunk (mchunkptr p)
{
size_t pagesize = GLRO (dl_pagesize);
INTERNAL_SIZE_T size = chunksize (p);
assert (chunk_is_mmapped (p));
/* Do nothing if the chunk is a faked mmapped chunk in the dumped
main arena. We never free this memory. */
if (DUMPED_MAIN_ARENA_CHUNK (p))
return;
uintptr_t mem = (uintptr_t) chunk2mem (p);
uintptr_t block = (uintptr_t) p - prev_size (p);
size_t total_size = prev_size (p) + size;
/* Unfortunately we have to do the compilers job by hand here. Normally
we would test BLOCK and TOTAL-SIZE separately for compliance with the
page size. But gcc does not recognize the optimization possibility
(in the moment at least) so we combine the two values into one before
the bit test. */
if (__glibc_unlikely ((block | total_size) & (pagesize - 1)) != 0
|| __glibc_unlikely (!powerof2 (mem & (pagesize - 1))))
malloc_printerr ("munmap_chunk(): invalid pointer");
atomic_decrement (&mp_.n_mmaps);
atomic_add (&mp_.mmapped_mem, -total_size);
/* If munmap failed the process virtual memory address space is in a
bad shape. Just leave the block hanging around, the process will
terminate shortly anyway since not much can be done. */
__munmap ((char *) block, total_size);
}
#if HAVE_MREMAP
static mchunkptr
mremap_chunk (mchunkptr p, size_t new_size)
{
size_t pagesize = GLRO (dl_pagesize);
INTERNAL_SIZE_T offset = prev_size (p);
INTERNAL_SIZE_T size = chunksize (p);
char *cp;
assert (chunk_is_mmapped (p));
uintptr_t block = (uintptr_t) p - offset;
uintptr_t mem = (uintptr_t) chunk2mem(p);
size_t total_size = offset + size;
if (__glibc_unlikely ((block | total_size) & (pagesize - 1)) != 0
|| __glibc_unlikely (!powerof2 (mem & (pagesize - 1))))
malloc_printerr("mremap_chunk(): invalid pointer");
/* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
new_size = ALIGN_UP (new_size + offset + SIZE_SZ, pagesize);
/* No need to remap if the number of pages does not change. */
if (total_size == new_size)
return p;
cp = (char *) __mremap ((char *) block, total_size, new_size,
MREMAP_MAYMOVE);
if (cp == MAP_FAILED)
return 0;
p = (mchunkptr) (cp + offset);
assert (aligned_OK (chunk2mem (p)));
assert (prev_size (p) == offset);
set_head (p, (new_size - offset) | IS_MMAPPED);
INTERNAL_SIZE_T new;
new = atomic_exchange_and_add (&mp_.mmapped_mem, new_size - size - offset)
+ new_size - size - offset;
atomic_max (&mp_.max_mmapped_mem, new);
return p;
}
#endif /* HAVE_MREMAP */
/*------------------------ Public wrappers. --------------------------------*/
#if USE_TCACHE
/* We overlay this structure on the user-data portion of a chunk when
the chunk is stored in the per-thread cache. */
typedef struct tcache_entry
{
struct tcache_entry *next;
/* This field exists to detect double frees. */
struct tcache_perthread_struct *key;
} tcache_entry;
/* There is one of these for each thread, which contains the
per-thread cache (hence "tcache_perthread_struct"). Keeping
overall size low is mildly important. Note that COUNTS and ENTRIES
are redundant (we could have just counted the linked list each
time), this is for performance reasons. */
typedef struct tcache_perthread_struct
{
char counts[TCACHE_MAX_BINS];
tcache_entry *entries[TCACHE_MAX_BINS];
} tcache_perthread_struct;
static __thread bool tcache_shutting_down = false;
static __thread tcache_perthread_struct *tcache = NULL;
/* Caller must ensure that we know tc_idx is valid and there's room
for more chunks. */
static __always_inline void
tcache_put (mchunkptr chunk, size_t tc_idx)
{
tcache_entry *e = (tcache_entry *) chunk2mem (chunk);
assert (tc_idx < TCACHE_MAX_BINS);
/* Mark this chunk as "in the tcache" so the test in _int_free will
detect a double free. */
e->key = tcache;
e->next = tcache->entries[tc_idx];
tcache->entries[tc_idx] = e;
++(tcache->counts[tc_idx]);
}
/* Caller must ensure that we know tc_idx is valid and there's
available chunks to remove. */
static __always_inline void *
tcache_get (size_t tc_idx)
{
tcache_entry *e = tcache->entries[tc_idx];
assert (tc_idx < TCACHE_MAX_BINS);
assert (tcache->counts[tc_idx] > 0);
tcache->entries[tc_idx] = e->next;
--(tcache->counts[tc_idx]);
e->key = NULL;
return (void *) e;
}
static void
tcache_thread_shutdown (void)
{
int i;
tcache_perthread_struct *tcache_tmp = tcache;
if (!tcache)
return;
/* Disable the tcache and prevent it from being reinitialized. */
tcache = NULL;
tcache_shutting_down = true;
/* Free all of the entries and the tcache itself back to the arena
heap for coalescing. */
for (i = 0; i < TCACHE_MAX_BINS; ++i)
{
while (tcache_tmp->entries[i])
{
tcache_entry *e = tcache_tmp->entries[i];
tcache_tmp->entries[i] = e->next;
__libc_free (e);
}
}
__libc_free (tcache_tmp);
}
static void
tcache_init(void)
{
mstate ar_ptr;
void *victim = 0;
const size_t bytes = sizeof (tcache_perthread_struct);
if (tcache_shutting_down)
return;
arena_get (ar_ptr, bytes);
victim = _int_malloc (ar_ptr, bytes);
if (!victim && ar_ptr != NULL)
{
ar_ptr = arena_get_retry (ar_ptr, bytes);
victim = _int_malloc (ar_ptr, bytes);
}
if (ar_ptr != NULL)
__libc_lock_unlock (ar_ptr->mutex);
/* In a low memory situation, we may not be able to allocate memory
- in which case, we just keep trying later. However, we
typically do this very early, so either there is sufficient
memory, or there isn't enough memory to do non-trivial
allocations anyway. */
if (victim)
{
tcache = (tcache_perthread_struct *) victim;
memset (tcache, 0, sizeof (tcache_perthread_struct));
}
}
# define MAYBE_INIT_TCACHE() \
if (__glibc_unlikely (tcache == NULL)) \
tcache_init();
#else /* !USE_TCACHE */
# define MAYBE_INIT_TCACHE()
static void
tcache_thread_shutdown (void)
{
/* Nothing to do if there is no thread cache. */
}
#endif /* !USE_TCACHE */
void *
__libc_malloc (size_t bytes)
{
mstate ar_ptr;
void *victim;
void *(*hook) (size_t, const void *)
= atomic_forced_read (__malloc_hook);
if (__builtin_expect (hook != NULL, 0))
return (*hook)(bytes, RETURN_ADDRESS (0));
#if USE_TCACHE
/* int_free also calls request2size, be careful to not pad twice. */
size_t tbytes;
checked_request2size (bytes, tbytes);
size_t tc_idx = csize2tidx (tbytes);
MAYBE_INIT_TCACHE ();
DIAG_PUSH_NEEDS_COMMENT;
if (tc_idx < mp_.tcache_bins
/*&& tc_idx < TCACHE_MAX_BINS*/ /* to appease gcc */
&& tcache
&& tcache->entries[tc_idx] != NULL)
{
return tcache_get (tc_idx);
}
DIAG_POP_NEEDS_COMMENT;
#endif
if (SINGLE_THREAD_P)
{
victim = _int_malloc (&main_arena, bytes);
assert (!victim || chunk_is_mmapped (mem2chunk (victim)) ||
&main_arena == arena_for_chunk (mem2chunk (victim)));
return victim;
}
arena_get (ar_ptr, bytes);
victim = _int_malloc (ar_ptr, bytes);
/* Retry with another arena only if we were able to find a usable arena
before. */
if (!victim && ar_ptr != NULL)
{
LIBC_PROBE (memory_malloc_retry, 1, bytes);
ar_ptr = arena_get_retry (ar_ptr, bytes);
victim = _int_malloc (ar_ptr, bytes);
}
if (ar_ptr != NULL)
__libc_lock_unlock (ar_ptr->mutex);
assert (!victim || chunk_is_mmapped (mem2chunk (victim)) ||
ar_ptr == arena_for_chunk (mem2chunk (victim)));
return victim;
}
libc_hidden_def (__libc_malloc)
void
__libc_free (void *mem)
{
mstate ar_ptr;
mchunkptr p; /* chunk corresponding to mem */
void (*hook) (void *, const void *)
= atomic_forced_read (__free_hook);
if (__builtin_expect (hook != NULL, 0))
{
(*hook)(mem, RETURN_ADDRESS (0));
return;
}
if (mem == 0) /* free(0) has no effect */
return;
p = mem2chunk (mem);
if (chunk_is_mmapped (p)) /* release mmapped memory. */
{
/* See if the dynamic brk/mmap threshold needs adjusting.
Dumped fake mmapped chunks do not affect the threshold. */
if (!mp_.no_dyn_threshold
&& chunksize_nomask (p) > mp_.mmap_threshold
&& chunksize_nomask (p) <= DEFAULT_MMAP_THRESHOLD_MAX
&& !DUMPED_MAIN_ARENA_CHUNK (p))
{
mp_.mmap_threshold = chunksize (p);
mp_.trim_threshold = 2 * mp_.mmap_threshold;
LIBC_PROBE (memory_mallopt_free_dyn_thresholds, 2,
mp_.mmap_threshold, mp_.trim_threshold);
}
munmap_chunk (p);
return;
}
MAYBE_INIT_TCACHE ();
ar_ptr = arena_for_chunk (p);
_int_free (ar_ptr, p, 0);
}
libc_hidden_def (__libc_free)
void *
__libc_realloc (void *oldmem, size_t bytes)
{
mstate ar_ptr;
INTERNAL_SIZE_T nb; /* padded request size */
void *newp; /* chunk to return */
void *(*hook) (void *, size_t, const void *) =
atomic_forced_read (__realloc_hook);
if (__builtin_expect (hook != NULL, 0))
return (*hook)(oldmem, bytes, RETURN_ADDRESS (0));
#if REALLOC_ZERO_BYTES_FREES
if (bytes == 0 && oldmem != NULL)
{
__libc_free (oldmem); return 0;
}
#endif
/* realloc of null is supposed to be same as malloc */
if (oldmem == 0)
return __libc_malloc (bytes);
/* chunk corresponding to oldmem */
const mchunkptr oldp = mem2chunk (oldmem);
/* its size */
const INTERNAL_SIZE_T oldsize = chunksize (oldp);
if (chunk_is_mmapped (oldp))
ar_ptr = NULL;
else
{
MAYBE_INIT_TCACHE ();
ar_ptr = arena_for_chunk (oldp);
}
/* Little security check which won't hurt performance: the allocator
never wrapps around at the end of the address space. Therefore
we can exclude some size values which might appear here by
accident or by "design" from some intruder. We need to bypass
this check for dumped fake mmap chunks from the old main arena
because the new malloc may provide additional alignment. */
if ((__builtin_expect ((uintptr_t) oldp > (uintptr_t) -oldsize, 0)
|| __builtin_expect (misaligned_chunk (oldp), 0))
&& !DUMPED_MAIN_ARENA_CHUNK (oldp))
malloc_printerr ("realloc(): invalid pointer");
checked_request2size (bytes, nb);
if (chunk_is_mmapped (oldp))
{
/* If this is a faked mmapped chunk from the dumped main arena,
always make a copy (and do not free the old chunk). */
if (DUMPED_MAIN_ARENA_CHUNK (oldp))
{
/* Must alloc, copy, free. */
void *newmem = __libc_malloc (bytes);
if (newmem == 0)
return NULL;
/* Copy as many bytes as are available from the old chunk
and fit into the new size. NB: The overhead for faked
mmapped chunks is only SIZE_SZ, not 2 * SIZE_SZ as for
regular mmapped chunks. */
if (bytes > oldsize - SIZE_SZ)
bytes = oldsize - SIZE_SZ;
memcpy (newmem, oldmem, bytes);
return newmem;
}
void *newmem;
#if HAVE_MREMAP
newp = mremap_chunk (oldp, nb);
if (newp)
return chunk2mem (newp);
#endif
/* Note the extra SIZE_SZ overhead. */
if (oldsize - SIZE_SZ >= nb)
return oldmem; /* do nothing */
/* Must alloc, copy, free. */
newmem = __libc_malloc (bytes);
if (newmem == 0)
return 0; /* propagate failure */
memcpy (newmem, oldmem, oldsize - 2 * SIZE_SZ);
munmap_chunk (oldp);
return newmem;
}
if (SINGLE_THREAD_P)
{
newp = _int_realloc (ar_ptr, oldp, oldsize, nb);
assert (!newp || chunk_is_mmapped (mem2chunk (newp)) ||
ar_ptr == arena_for_chunk (mem2chunk (newp)));
return newp;
}
__libc_lock_lock (ar_ptr->mutex);
newp = _int_realloc (ar_ptr, oldp, oldsize, nb);
__libc_lock_unlock (ar_ptr->mutex);
assert (!newp || chunk_is_mmapped (mem2chunk (newp)) ||
ar_ptr == arena_for_chunk (mem2chunk (newp)));
if (newp == NULL)
{
/* Try harder to allocate memory in other arenas. */
LIBC_PROBE (memory_realloc_retry, 2, bytes, oldmem);
newp = __libc_malloc (bytes);
if (newp != NULL)
{
memcpy (newp, oldmem, oldsize - SIZE_SZ);
_int_free (ar_ptr, oldp, 0);
}
}
return newp;
}
libc_hidden_def (__libc_realloc)
void *
__libc_memalign (size_t alignment, size_t bytes)
{
void *address = RETURN_ADDRESS (0);
return _mid_memalign (alignment, bytes, address);
}
static void *
_mid_memalign (size_t alignment, size_t bytes, void *address)
{
mstate ar_ptr;
void *p;
void *(*hook) (size_t, size_t, const void *) =
atomic_forced_read (__memalign_hook);
if (__builtin_expect (hook != NULL, 0))
return (*hook)(alignment, bytes, address);
/* If we need less alignment than we give anyway, just relay to malloc. */
if (alignment <= MALLOC_ALIGNMENT)
return __libc_malloc (bytes);
/* Otherwise, ensure that it is at least a minimum chunk size */
if (alignment < MINSIZE)
alignment = MINSIZE;
/* If the alignment is greater than SIZE_MAX / 2 + 1 it cannot be a
power of 2 and will cause overflow in the check below. */
if (alignment > SIZE_MAX / 2 + 1)
{
__set_errno (EINVAL);
return 0;
}
/* Check for overflow. */
if (bytes > SIZE_MAX - alignment - MINSIZE)
{
__set_errno (ENOMEM);
return 0;
}
/* Make sure alignment is power of 2. */
if (!powerof2 (alignment))
{
size_t a = MALLOC_ALIGNMENT * 2;
while (a < alignment)
a <<= 1;
alignment = a;
}
if (SINGLE_THREAD_P)
{
p = _int_memalign (&main_arena, alignment, bytes);
assert (!p || chunk_is_mmapped (mem2chunk (p)) ||
&main_arena == arena_for_chunk (mem2chunk (p)));
return p;
}
arena_get (ar_ptr, bytes + alignment + MINSIZE);
p = _int_memalign (ar_ptr, alignment, bytes);
if (!p && ar_ptr != NULL)
{
LIBC_PROBE (memory_memalign_retry, 2, bytes, alignment);
ar_ptr = arena_get_retry (ar_ptr, bytes);
p = _int_memalign (ar_ptr, alignment, bytes);
}
if (ar_ptr != NULL)
__libc_lock_unlock (ar_ptr->mutex);
assert (!p || chunk_is_mmapped (mem2chunk (p)) ||
ar_ptr == arena_for_chunk (mem2chunk (p)));
return p;
}
/* For ISO C11. */
weak_alias (__libc_memalign, aligned_alloc)
libc_hidden_def (__libc_memalign)
void *
__libc_valloc (size_t bytes)
{
if (__malloc_initialized < 0)
ptmalloc_init ();
void *address = RETURN_ADDRESS (0);
size_t pagesize = GLRO (dl_pagesize);
return _mid_memalign (pagesize, bytes, address);
}
void *
__libc_pvalloc (size_t bytes)
{
if (__malloc_initialized < 0)
ptmalloc_init ();
void *address = RETURN_ADDRESS (0);
size_t pagesize = GLRO (dl_pagesize);
size_t rounded_bytes = ALIGN_UP (bytes, pagesize);
/* Check for overflow. */
if (bytes > SIZE_MAX - 2 * pagesize - MINSIZE)
{
__set_errno (ENOMEM);
return 0;
}
return _mid_memalign (pagesize, rounded_bytes, address);
}
void *
__libc_calloc (size_t n, size_t elem_size)
{
mstate av;
mchunkptr oldtop, p;
INTERNAL_SIZE_T bytes, sz, csz, oldtopsize;
void *mem;
unsigned long clearsize;
unsigned long nclears;
INTERNAL_SIZE_T *d;
/* size_t is unsigned so the behavior on overflow is defined. */
bytes = n * elem_size;
#define HALF_INTERNAL_SIZE_T \
(((INTERNAL_SIZE_T) 1) << (8 * sizeof (INTERNAL_SIZE_T) / 2))
if (__builtin_expect ((n | elem_size) >= HALF_INTERNAL_SIZE_T, 0))
{
if (elem_size != 0 && bytes / elem_size != n)
{
__set_errno (ENOMEM);
return 0;
}
}
void *(*hook) (size_t, const void *) =
atomic_forced_read (__malloc_hook);
if (__builtin_expect (hook != NULL, 0))
{
sz = bytes;
mem = (*hook)(sz, RETURN_ADDRESS (0));
if (mem == 0)
return 0;
return memset (mem, 0, sz);
}
sz = bytes;
MAYBE_INIT_TCACHE ();
if (SINGLE_THREAD_P)
av = &main_arena;
else
arena_get (av, sz);
if (av)
{
/* Check if we hand out the top chunk, in which case there may be no
need to clear. */
#if MORECORE_CLEARS
oldtop = top (av);
oldtopsize = chunksize (top (av));
# if MORECORE_CLEARS < 2
/* Only newly allocated memory is guaranteed to be cleared. */
if (av == &main_arena &&
oldtopsize < mp_.sbrk_base + av->max_system_mem - (char *) oldtop)
oldtopsize = (mp_.sbrk_base + av->max_system_mem - (char *) oldtop);
# endif
if (av != &main_arena)
{
heap_info *heap = heap_for_ptr (oldtop);
if (oldtopsize < (char *) heap + heap->mprotect_size - (char *) oldtop)
oldtopsize = (char *) heap + heap->mprotect_size - (char *) oldtop;
}
#endif
}
else
{
/* No usable arenas. */
oldtop = 0;
oldtopsize = 0;
}
mem = _int_malloc (av, sz);
assert (!mem || chunk_is_mmapped (mem2chunk (mem)) ||
av == arena_for_chunk (mem2chunk (mem)));
if (!SINGLE_THREAD_P)
{
if (mem == 0 && av != NULL)
{
LIBC_PROBE (memory_calloc_retry, 1, sz);
av = arena_get_retry (av, sz);
mem = _int_malloc (av, sz);
}
if (av != NULL)
__libc_lock_unlock (av->mutex);
}
/* Allocation failed even after a retry. */
if (mem == 0)
return 0;
p = mem2chunk (mem);
/* Two optional cases in which clearing not necessary */
if (chunk_is_mmapped (p))
{
if (__builtin_expect (perturb_byte, 0))
return memset (mem, 0, sz);
return mem;
}
csz = chunksize (p);
#if MORECORE_CLEARS
if (perturb_byte == 0 && (p == oldtop && csz > oldtopsize))
{
/* clear only the bytes from non-freshly-sbrked memory */
csz = oldtopsize;
}
#endif
/* Unroll clear of <= 36 bytes (72 if 8byte sizes). We know that
contents have an odd number of INTERNAL_SIZE_T-sized words;
minimally 3. */
d = (INTERNAL_SIZE_T *) mem;
clearsize = csz - SIZE_SZ;
nclears = clearsize / sizeof (INTERNAL_SIZE_T);
assert (nclears >= 3);
if (nclears > 9)
return memset (d, 0, clearsize);
else
{
*(d + 0) = 0;
*(d + 1) = 0;
*(d + 2) = 0;
if (nclears > 4)
{
*(d + 3) = 0;
*(d + 4) = 0;
if (nclears > 6)
{
*(d + 5) = 0;
*(d + 6) = 0;
if (nclears > 8)
{
*(d + 7) = 0;
*(d + 8) = 0;
}
}
}
}
return mem;
}
/*
------------------------------ malloc ------------------------------
*/
static void *
_int_malloc (mstate av, size_t bytes)
{
INTERNAL_SIZE_T nb; /* normalized request size */
unsigned int idx; /* associated bin index */
mbinptr bin; /* associated bin */
mchunkptr victim; /* inspected/selected chunk */
INTERNAL_SIZE_T size; /* its size */
int victim_index; /* its bin index */
mchunkptr remainder; /* remainder from a split */
unsigned long remainder_size; /* its size */
unsigned int block; /* bit map traverser */
unsigned int bit; /* bit map traverser */
unsigned int map; /* current word of binmap */
mchunkptr fwd; /* misc temp for linking */
mchunkptr bck; /* misc temp for linking */
#if USE_TCACHE
size_t tcache_unsorted_count; /* count of unsorted chunks processed */
#endif
/*
Convert request size to internal form by adding SIZE_SZ bytes
overhead plus possibly more to obtain necessary alignment and/or
to obtain a size of at least MINSIZE, the smallest allocatable
size. Also, checked_request2size traps (returning 0) request sizes
that are so large that they wrap around zero when padded and
aligned.
*/
checked_request2size (bytes, nb);
/* There are no usable arenas. Fall back to sysmalloc to get a chunk from
mmap. */
if (__glibc_unlikely (av == NULL))
{
void *p = sysmalloc (nb, av);
if (p != NULL)
alloc_perturb (p, bytes);
return p;
}
/*
If the size qualifies as a fastbin, first check corresponding bin.
This code is safe to execute even if av is not yet initialized, so we
can try it without checking, which saves some time on this fast path.
*/
#define REMOVE_FB(fb, victim, pp) \
do \
{ \
victim = pp; \
if (victim == NULL) \
break; \
} \
while ((pp = catomic_compare_and_exchange_val_acq (fb, victim->fd, victim)) \
!= victim); \
if ((unsigned long) (nb) <= (unsigned long) (get_max_fast ()))
{
idx = fastbin_index (nb);
mfastbinptr *fb = &fastbin (av, idx);
mchunkptr pp;
victim = *fb;
if (victim != NULL)
{
if (SINGLE_THREAD_P)
*fb = victim->fd;
else
REMOVE_FB (fb, pp, victim);
if (__glibc_likely (victim != NULL))
{
size_t victim_idx = fastbin_index (chunksize (victim));
if (__builtin_expect (victim_idx != idx, 0))
malloc_printerr ("malloc(): memory corruption (fast)");
check_remalloced_chunk (av, victim, nb);
#if USE_TCACHE
/* While we're here, if we see other chunks of the same size,
stash them in the tcache. */
size_t tc_idx = csize2tidx (nb);
if (tcache && tc_idx < mp_.tcache_bins)
{
mchunkptr tc_victim;
/* While bin not empty and tcache not full, copy chunks. */
while (tcache->counts[tc_idx] < mp_.tcache_count
&& (tc_victim = *fb) != NULL)
{
if (SINGLE_THREAD_P)
*fb = tc_victim->fd;
else
{
REMOVE_FB (fb, pp, tc_victim);
if (__glibc_unlikely (tc_victim == NULL))
break;
}
tcache_put (tc_victim, tc_idx);
}
}
#endif
void *p = chunk2mem (victim);
alloc_perturb (p, bytes);
return p;
}
}
}
/*
If a small request, check regular bin. Since these "smallbins"
hold one size each, no searching within bins is necessary.
(For a large request, we need to wait until unsorted chunks are
processed to find best fit. But for small ones, fits are exact
anyway, so we can check now, which is faster.)
*/
if (in_smallbin_range (nb))
{
idx = smallbin_index (nb);
bin = bin_at (av, idx);
if ((victim = last (bin)) != bin)
{
bck = victim->bk;
if (__glibc_unlikely (bck->fd != victim))
malloc_printerr ("malloc(): smallbin double linked list corrupted");
set_inuse_bit_at_offset (victim, nb);
bin->bk = bck;
bck->fd = bin;
if (av != &main_arena)
set_non_main_arena (victim);
check_malloced_chunk (av, victim, nb);
#if USE_TCACHE
/* While we're here, if we see other chunks of the same size,
stash them in the tcache. */
size_t tc_idx = csize2tidx (nb);
if (tcache && tc_idx < mp_.tcache_bins)
{
mchunkptr tc_victim;
/* While bin not empty and tcache not full, copy chunks over. */
while (tcache->counts[tc_idx] < mp_.tcache_count
&& (tc_victim = last (bin)) != bin)
{
if (tc_victim != 0)
{
bck = tc_victim->bk;
set_inuse_bit_at_offset (tc_victim, nb);
if (av != &main_arena)
set_non_main_arena (tc_victim);
bin->bk = bck;
bck->fd = bin;
tcache_put (tc_victim, tc_idx);
}
}
}
#endif
void *p = chunk2mem (victim);
alloc_perturb (p, bytes);
return p;
}
}
/*
If this is a large request, consolidate fastbins before continuing.
While it might look excessive to kill all fastbins before
even seeing if there is space available, this avoids
fragmentation problems normally associated with fastbins.
Also, in practice, programs tend to have runs of either small or
large requests, but less often mixtures, so consolidation is not
invoked all that often in most programs. And the programs that
it is called frequently in otherwise tend to fragment.
*/
else
{
idx = largebin_index (nb);
if (atomic_load_relaxed (&av->have_fastchunks))
malloc_consolidate (av);
}
/*
Process recently freed or remaindered chunks, taking one only if
it is exact fit, or, if this a small request, the chunk is remainder from
the most recent non-exact fit. Place other traversed chunks in
bins. Note that this step is the only place in any routine where
chunks are placed in bins.
The outer loop here is needed because we might not realize until
near the end of malloc that we should have consolidated, so must
do so and retry. This happens at most once, and only when we would
otherwise need to expand memory to service a "small" request.
*/
#if USE_TCACHE
INTERNAL_SIZE_T tcache_nb = 0;
size_t tc_idx = csize2tidx (nb);
if (tcache && tc_idx < mp_.tcache_bins)
tcache_nb = nb;
int return_cached = 0;
tcache_unsorted_count = 0;
#endif
for (;; )
{
int iters = 0;
while ((victim = unsorted_chunks (av)->bk) != unsorted_chunks (av))
{
bck = victim->bk;
size = chunksize (victim);
mchunkptr next = chunk_at_offset (victim, size);
if (__glibc_unlikely (size <= 2 * SIZE_SZ)
|| __glibc_unlikely (size > av->system_mem))
malloc_printerr ("malloc(): invalid size (unsorted)");
if (__glibc_unlikely (chunksize_nomask (next) < 2 * SIZE_SZ)
|| __glibc_unlikely (chunksize_nomask (next) > av->system_mem))
malloc_printerr ("malloc(): invalid next size (unsorted)");
if (__glibc_unlikely ((prev_size (next) & ~(SIZE_BITS)) != size))
malloc_printerr ("malloc(): mismatching next->prev_size (unsorted)");
if (__glibc_unlikely (bck->fd != victim)
|| __glibc_unlikely (victim->fd != unsorted_chunks (av)))
malloc_printerr ("malloc(): unsorted double linked list corrupted");
if (__glibc_unlikely (prev_inuse (next)))
malloc_printerr ("malloc(): invalid next->prev_inuse (unsorted)");
/*
If a small request, try to use last remainder if it is the
only chunk in unsorted bin. This helps promote locality for
runs of consecutive small requests. This is the only
exception to best-fit, and applies only when there is
no exact fit for a small chunk.
*/
if (in_smallbin_range (nb) &&
bck == unsorted_chunks (av) &&
victim == av->last_remainder &&
(unsigned long) (size) > (unsigned long) (nb + MINSIZE))
{
/* split and reattach remainder */
remainder_size = size - nb;
remainder = chunk_at_offset (victim, nb);
unsorted_chunks (av)->bk = unsorted_chunks (av)->fd = remainder;
av->last_remainder = remainder;
remainder->bk = remainder->fd = unsorted_chunks (av);
if (!in_smallbin_range (remainder_size))
{
remainder->fd_nextsize = NULL;
remainder->bk_nextsize = NULL;
}
set_head (victim, nb | PREV_INUSE |
(av != &main_arena ? NON_MAIN_ARENA : 0));
set_head (remainder, remainder_size | PREV_INUSE);
set_foot (remainder, remainder_size);
check_malloced_chunk (av, victim, nb);
void *p = chunk2mem (victim);
alloc_perturb (p, bytes);
return p;
}
/* remove from unsorted list */
if (__glibc_unlikely (bck->fd != victim))
malloc_printerr ("malloc(): corrupted unsorted chunks 3");
unsorted_chunks (av)->bk = bck;
bck->fd = unsorted_chunks (av);
/* Take now instead of binning if exact fit */
if (size == nb)
{
set_inuse_bit_at_offset (victim, size);
if (av != &main_arena)
set_non_main_arena (victim);
#if USE_TCACHE
/* Fill cache first, return to user only if cache fills.
We may return one of these chunks later. */
if (tcache_nb
&& tcache->counts[tc_idx] < mp_.tcache_count)
{
tcache_put (victim, tc_idx);
return_cached = 1;
continue;
}
else
{
#endif
check_malloced_chunk (av, victim, nb);
void *p = chunk2mem (victim);
alloc_perturb (p, bytes);
return p;
#if USE_TCACHE
}
#endif
}
/* place chunk in bin */
if (in_smallbin_range (size))
{
victim_index = smallbin_index (size);
bck = bin_at (av, victim_index);
fwd = bck->fd;
}
else
{
victim_index = largebin_index (size);
bck = bin_at (av, victim_index);
fwd = bck->fd;
/* maintain large bins in sorted order */
if (fwd != bck)
{
/* Or with inuse bit to speed comparisons */
size |= PREV_INUSE;
/* if smaller than smallest, bypass loop below */
assert (chunk_main_arena (bck->bk));
if ((unsigned long) (size)
< (unsigned long) chunksize_nomask (bck->bk))
{
fwd = bck;
bck = bck->bk;
victim->fd_nextsize = fwd->fd;
victim->bk_nextsize = fwd->fd->bk_nextsize;
fwd->fd->bk_nextsize = victim->bk_nextsize->fd_nextsize = victim;
}
else
{
assert (chunk_main_arena (fwd));
while ((unsigned long) size < chunksize_nomask (fwd))
{
fwd = fwd->fd_nextsize;
assert (chunk_main_arena (fwd));
}
if ((unsigned long) size
== (unsigned long) chunksize_nomask (fwd))
/* Always insert in the second position. */
fwd = fwd->fd;
else
{
victim->fd_nextsize = fwd;
victim->bk_nextsize = fwd->bk_nextsize;
if (__glibc_unlikely (fwd->bk_nextsize->fd_nextsize != fwd))
malloc_printerr ("malloc(): largebin double linked list corrupted (nextsize)");
fwd->bk_nextsize = victim;
victim->bk_nextsize->fd_nextsize = victim;
}
bck = fwd->bk;
if (bck->fd != fwd)
malloc_printerr ("malloc(): largebin double linked list corrupted (bk)");
}
}
else
victim->fd_nextsize = victim->bk_nextsize = victim;
}
mark_bin (av, victim_index);
victim->bk = bck;
victim->fd = fwd;
fwd->bk = victim;
bck->fd = victim;
#if USE_TCACHE
/* If we've processed as many chunks as we're allowed while
filling the cache, return one of the cached ones. */
++tcache_unsorted_count;
if (return_cached
&& mp_.tcache_unsorted_limit > 0
&& tcache_unsorted_count > mp_.tcache_unsorted_limit)
{
return tcache_get (tc_idx);
}
#endif
#define MAX_ITERS 10000
if (++iters >= MAX_ITERS)
break;
}
#if USE_TCACHE
/* If all the small chunks we found ended up cached, return one now. */
if (return_cached)
{
return tcache_get (tc_idx);
}
#endif
/*
If a large request, scan through the chunks of current bin in
sorted order to find smallest that fits. Use the skip list for this.
*/
if (!in_smallbin_range (nb))
{
bin = bin_at (av, idx);
/* skip scan if empty or largest chunk is too small */
if ((victim = first (bin)) != bin
&& (unsigned long) chunksize_nomask (victim)
>= (unsigned long) (nb))
{
victim = victim->bk_nextsize;
while (((unsigned long) (size = chunksize (victim)) <
(unsigned long) (nb)))
victim = victim->bk_nextsize;
/* Avoid removing the first entry for a size so that the skip
list does not have to be rerouted. */
if (victim != last (bin)
&& chunksize_nomask (victim)
== chunksize_nomask (victim->fd))
victim = victim->fd;
remainder_size = size - nb;
unlink_chunk (av, victim);
/* Exhaust */
if (remainder_size < MINSIZE)
{
set_inuse_bit_at_offset (victim, size);
if (av != &main_arena)
set_non_main_arena (victim);
}
/* Split */
else
{
remainder = chunk_at_offset (victim, nb);
/* We cannot assume the unsorted list is empty and therefore
have to perform a complete insert here. */
bck = unsorted_chunks (av);
fwd = bck->fd;
if (__glibc_unlikely (fwd->bk != bck))
malloc_printerr ("malloc(): corrupted unsorted chunks");
remainder->bk = bck;
remainder->fd = fwd;
bck->fd = remainder;
fwd->bk = remainder;
if (!in_smallbin_range (remainder_size))
{
remainder->fd_nextsize = NULL;
remainder->bk_nextsize = NULL;
}
set_head (victim, nb | PREV_INUSE |
(av != &main_arena ? NON_MAIN_ARENA : 0));
set_head (remainder, remainder_size | PREV_INUSE);
set_foot (remainder, remainder_size);
}
check_malloced_chunk (av, victim, nb);
void *p = chunk2mem (victim);
alloc_perturb (p, bytes);
return p;
}
}
/*
Search for a chunk by scanning bins, starting with next largest
bin. This search is strictly by best-fit; i.e., the smallest
(with ties going to approximately the least recently used) chunk
that fits is selected.
The bitmap avoids needing to check that most blocks are nonempty.
The particular case of skipping all bins during warm-up phases
when no chunks have been returned yet is faster than it might look.
*/
++idx;
bin = bin_at (av, idx);
block = idx2block (idx);
map = av->binmap[block];
bit = idx2bit (idx);
for (;; )
{
/* Skip rest of block if there are no more set bits in this block. */
if (bit > map || bit == 0)
{
do
{
if (++block >= BINMAPSIZE) /* out of bins */
goto use_top;
}
while ((map = av->binmap[block]) == 0);
bin = bin_at (av, (block << BINMAPSHIFT));
bit = 1;
}
/* Advance to bin with set bit. There must be one. */
while ((bit & map) == 0)
{
bin = next_bin (bin);
bit <<= 1;
assert (bit != 0);
}
/* Inspect the bin. It is likely to be non-empty */
victim = last (bin);
/* If a false alarm (empty bin), clear the bit. */
if (victim == bin)
{
av->binmap[block] = map &= ~bit; /* Write through */
bin = next_bin (bin);
bit <<= 1;
}
else
{
size = chunksize (victim);
/* We know the first chunk in this bin is big enough to use. */
assert ((unsigned long) (size) >= (unsigned long) (nb));
remainder_size = size - nb;
/* unlink */
unlink_chunk (av, victim);
/* Exhaust */
if (remainder_size < MINSIZE)
{
set_inuse_bit_at_offset (victim, size);
if (av != &main_arena)
set_non_main_arena (victim);
}
/* Split */
else
{
remainder = chunk_at_offset (victim, nb);
/* We cannot assume the unsorted list is empty and therefore
have to perform a complete insert here. */
bck = unsorted_chunks (av);
fwd = bck->fd;
if (__glibc_unlikely (fwd->bk != bck))
malloc_printerr ("malloc(): corrupted unsorted chunks 2");
remainder->bk = bck;
remainder->fd = fwd;
bck->fd = remainder;
fwd->bk = remainder;
/* advertise as last remainder */
if (in_smallbin_range (nb))
av->last_remainder = remainder;
if (!in_smallbin_range (remainder_size))
{
remainder->fd_nextsize = NULL;
remainder->bk_nextsize = NULL;
}
set_head (victim, nb | PREV_INUSE |
(av != &main_arena ? NON_MAIN_ARENA : 0));
set_head (remainder, remainder_size | PREV_INUSE);
set_foot (remainder, remainder_size);
}
check_malloced_chunk (av, victim, nb);
void *p = chunk2mem (victim);
alloc_perturb (p, bytes);
return p;
}
}
use_top:
/*
If large enough, split off the chunk bordering the end of memory
(held in av->top). Note that this is in accord with the best-fit
search rule. In effect, av->top is treated as larger (and thus
less well fitting) than any other available chunk since it can
be extended to be as large as necessary (up to system
limitations).
We require that av->top always exists (i.e., has size >=
MINSIZE) after initialization, so if it would otherwise be
exhausted by current request, it is replenished. (The main
reason for ensuring it exists is that we may need MINSIZE space
to put in fenceposts in sysmalloc.)
*/
victim = av->top;
size = chunksize (victim);
if (__glibc_unlikely (size > av->system_mem))
malloc_printerr ("malloc(): corrupted top size");
if ((unsigned long) (size) >= (unsigned long) (nb + MINSIZE))
{
remainder_size = size - nb;
remainder = chunk_at_offset (victim, nb);
av->top = remainder;
set_head (victim, nb | PREV_INUSE |
(av != &main_arena ? NON_MAIN_ARENA : 0));
set_head (remainder, remainder_size | PREV_INUSE);
check_malloced_chunk (av, victim, nb);
void *p = chunk2mem (victim);
alloc_perturb (p, bytes);
return p;
}
/* When we are using atomic ops to free fast chunks we can get
here for all block sizes. */
else if (atomic_load_relaxed (&av->have_fastchunks))
{
malloc_consolidate (av);
/* restore original bin index */
if (in_smallbin_range (nb))
idx = smallbin_index (nb);
else
idx = largebin_index (nb);
}
/*
Otherwise, relay to handle system-dependent cases
*/
else
{
void *p = sysmalloc (nb, av);
if (p != NULL)
alloc_perturb (p, bytes);
return p;
}
}
}
/*
------------------------------ free ------------------------------
*/
static void
_int_free (mstate av, mchunkptr p, int have_lock)
{
INTERNAL_SIZE_T size; /* its size */
mfastbinptr *fb; /* associated fastbin */
mchunkptr nextchunk; /* next contiguous chunk */
INTERNAL_SIZE_T nextsize; /* its size */
int nextinuse; /* true if nextchunk is used */
INTERNAL_SIZE_T prevsize; /* size of previous contiguous chunk */
mchunkptr bck; /* misc temp for linking */
mchunkptr fwd; /* misc temp for linking */
size = chunksize (p);
/* Little security check which won't hurt performance: the
allocator never wrapps around at the end of the address space.
Therefore we can exclude some size values which might appear
here by accident or by "design" from some intruder. */
if (__builtin_expect ((uintptr_t) p > (uintptr_t) -size, 0)
|| __builtin_expect (misaligned_chunk (p), 0))
malloc_printerr ("free(): invalid pointer");
/* We know that each chunk is at least MINSIZE bytes in size or a
multiple of MALLOC_ALIGNMENT. */
if (__glibc_unlikely (size < MINSIZE || !aligned_OK (size)))
malloc_printerr ("free(): invalid size");
check_inuse_chunk(av, p);
#if USE_TCACHE
{
size_t tc_idx = csize2tidx (size);
if (tcache != NULL && tc_idx < mp_.tcache_bins)
{
/* Check to see if it's already in the tcache. */
tcache_entry *e = (tcache_entry *) chunk2mem (p);
/* This test succeeds on double free. However, we don't 100%
trust it (it also matches random payload data at a 1 in
2^<size_t> chance), so verify it's not an unlikely
coincidence before aborting. */
if (__glibc_unlikely (e->key == tcache))
{
tcache_entry *tmp;
LIBC_PROBE (memory_tcache_double_free, 2, e, tc_idx);
for (tmp = tcache->entries[tc_idx];
tmp;
tmp = tmp->next)
if (tmp == e)
malloc_printerr ("free(): double free detected in tcache 2");
/* If we get here, it was a coincidence. We've wasted a
few cycles, but don't abort. */
}
if (tcache->counts[tc_idx] < mp_.tcache_count)
{
tcache_put (p, tc_idx);
return;
}
}
}
#endif
/*
If eligible, place chunk on a fastbin so it can be found
and used quickly in malloc.
*/
if ((unsigned long)(size) <= (unsigned long)(get_max_fast ())
#if TRIM_FASTBINS
/*
If TRIM_FASTBINS set, don't place chunks
bordering top into fastbins
*/
&& (chunk_at_offset(p, size) != av->top)
#endif
) {
if (__builtin_expect (chunksize_nomask (chunk_at_offset (p, size))
<= 2 * SIZE_SZ, 0)
|| __builtin_expect (chunksize (chunk_at_offset (p, size))
>= av->system_mem, 0))
{
bool fail = true;
/* We might not have a lock at this point and concurrent modifications
of system_mem might result in a false positive. Redo the test after
getting the lock. */
if (!have_lock)
{
__libc_lock_lock (av->mutex);
fail = (chunksize_nomask (chunk_at_offset (p, size)) <= 2 * SIZE_SZ
|| chunksize (chunk_at_offset (p, size)) >= av->system_mem);
__libc_lock_unlock (av->mutex);
}
if (fail)
malloc_printerr ("free(): invalid next size (fast)");
}
free_perturb (chunk2mem(p), size - 2 * SIZE_SZ);
atomic_store_relaxed (&av->have_fastchunks, true);
unsigned int idx = fastbin_index(size);
fb = &fastbin (av, idx);
/* Atomically link P to its fastbin: P->FD = *FB; *FB = P; */
mchunkptr old = *fb, old2;
if (SINGLE_THREAD_P)
{
/* Check that the top of the bin is not the record we are going to
add (i.e., double free). */
if (__builtin_expect (old == p, 0))
malloc_printerr ("double free or corruption (fasttop)");
p->fd = old;
*fb = p;
}
else
do
{
/* Check that the top of the bin is not the record we are going to
add (i.e., double free). */
if (__builtin_expect (old == p, 0))
malloc_printerr ("double free or corruption (fasttop)");
p->fd = old2 = old;
}
while ((old = catomic_compare_and_exchange_val_rel (fb, p, old2))
!= old2);
/* Check that size of fastbin chunk at the top is the same as
size of the chunk that we are adding. We can dereference OLD
only if we have the lock, otherwise it might have already been
allocated again. */
if (have_lock && old != NULL
&& __builtin_expect (fastbin_index (chunksize (old)) != idx, 0))
malloc_printerr ("invalid fastbin entry (free)");
}
/*
Consolidate other non-mmapped chunks as they arrive.
*/
else if (!chunk_is_mmapped(p)) {
/* If we're single-threaded, don't lock the arena. */
if (SINGLE_THREAD_P)
have_lock = true;
if (!have_lock)
__libc_lock_lock (av->mutex);
nextchunk = chunk_at_offset(p, size);
/* Lightweight tests: check whether the block is already the
top block. */
if (__glibc_unlikely (p == av->top))
malloc_printerr ("double free or corruption (top)");
/* Or whether the next chunk is beyond the boundaries of the arena. */
if (__builtin_expect (contiguous (av)
&& (char *) nextchunk
>= ((char *) av->top + chunksize(av->top)), 0))
malloc_printerr ("double free or corruption (out)");
/* Or whether the block is actually not marked used. */
if (__glibc_unlikely (!prev_inuse(nextchunk)))
malloc_printerr ("double free or corruption (!prev)");
nextsize = chunksize(nextchunk);
if (__builtin_expect (chunksize_nomask (nextchunk) <= 2 * SIZE_SZ, 0)
|| __builtin_expect (nextsize >= av->system_mem, 0))
malloc_printerr ("free(): invalid next size (normal)");
free_perturb (chunk2mem(p), size - 2 * SIZE_SZ);
/* consolidate backward */
if (!prev_inuse(p)) {
prevsize = prev_size (p);
size += prevsize;
p = chunk_at_offset(p, -((long) prevsize));
if (__glibc_unlikely (chunksize(p) != prevsize))
malloc_printerr ("corrupted size vs. prev_size while consolidating");
unlink_chunk (av, p);
}
if (nextchunk != av->top) {
/* get and clear inuse bit */
nextinuse = inuse_bit_at_offset(nextchunk, nextsize);
/* consolidate forward */
if (!nextinuse) {
unlink_chunk (av, nextchunk);
size += nextsize;
} else
clear_inuse_bit_at_offset(nextchunk, 0);
/*
Place the chunk in unsorted chunk list. Chunks are
not placed into regular bins until after they have
been given one chance to be used in malloc.
*/
bck = unsorted_chunks(av);
fwd = bck->fd;
if (__glibc_unlikely (fwd->bk != bck))
malloc_printerr ("free(): corrupted unsorted chunks");
p->fd = fwd;
p->bk = bck;
if (!in_smallbin_range(size))
{
p->fd_nextsize = NULL;
p->bk_nextsize = NULL;
}
bck->fd = p;
fwd->bk = p;
set_head(p, size | PREV_INUSE);
set_foot(p, size);
check_free_chunk(av, p);
}
/*
If the chunk borders the current high end of memory,
consolidate into top
*/
else {
size += nextsize;
set_head(p, size | PREV_INUSE);
av->top = p;
check_chunk(av, p);
}
/*
If freeing a large space, consolidate possibly-surrounding
chunks. Then, if the total unused topmost memory exceeds trim
threshold, ask malloc_trim to reduce top.
Unless max_fast is 0, we don't know if there are fastbins
bordering top, so we cannot tell for sure whether threshold
has been reached unless fastbins are consolidated. But we
don't want to consolidate on each free. As a compromise,
consolidation is performed if FASTBIN_CONSOLIDATION_THRESHOLD
is reached.
*/
if ((unsigned long)(size) >= FASTBIN_CONSOLIDATION_THRESHOLD) {
if (atomic_load_relaxed (&av->have_fastchunks))
malloc_consolidate(av);
if (av == &main_arena) {
#ifndef MORECORE_CANNOT_TRIM
if ((unsigned long)(chunksize(av->top)) >=
(unsigned long)(mp_.trim_threshold))
systrim(mp_.top_pad, av);
#endif
} else {
/* Always try heap_trim(), even if the top chunk is not
large, because the corresponding heap might go away. */
heap_info *heap = heap_for_ptr(top(av));
assert(heap->ar_ptr == av);
heap_trim(heap, mp_.top_pad);
}
}
if (!have_lock)
__libc_lock_unlock (av->mutex);
}
/*
If the chunk was allocated via mmap, release via munmap().
*/
else {
munmap_chunk (p);
}
}
/*
------------------------- malloc_consolidate -------------------------
malloc_consolidate is a specialized version of free() that tears
down chunks held in fastbins. Free itself cannot be used for this
purpose since, among other things, it might place chunks back onto
fastbins. So, instead, we need to use a minor variant of the same
code.
*/
static void malloc_consolidate(mstate av)
{
mfastbinptr* fb; /* current fastbin being consolidated */
mfastbinptr* maxfb; /* last fastbin (for loop control) */
mchunkptr p; /* current chunk being consolidated */
mchunkptr nextp; /* next chunk to consolidate */
mchunkptr unsorted_bin; /* bin header */
mchunkptr first_unsorted; /* chunk to link to */
/* These have same use as in free() */
mchunkptr nextchunk;
INTERNAL_SIZE_T size;
INTERNAL_SIZE_T nextsize;
INTERNAL_SIZE_T prevsize;
int nextinuse;
atomic_store_relaxed (&av->have_fastchunks, false);
unsorted_bin = unsorted_chunks(av);
/*
Remove each chunk from fast bin and consolidate it, placing it
then in unsorted bin. Among other reasons for doing this,
placing in unsorted bin avoids needing to calculate actual bins
until malloc is sure that chunks aren't immediately going to be
reused anyway.
*/
maxfb = &fastbin (av, NFASTBINS - 1);
fb = &fastbin (av, 0);
do {
p = atomic_exchange_acq (fb, NULL);
if (p != 0) {
do {
{
unsigned int idx = fastbin_index (chunksize (p));
if ((&fastbin (av, idx)) != fb)
malloc_printerr ("malloc_consolidate(): invalid chunk size");
}
check_inuse_chunk(av, p);
nextp = p->fd;
/* Slightly streamlined version of consolidation code in free() */
size = chunksize (p);
nextchunk = chunk_at_offset(p, size);
nextsize = chunksize(nextchunk);
if (!prev_inuse(p)) {
prevsize = prev_size (p);
size += prevsize;
p = chunk_at_offset(p, -((long) prevsize));
if (__glibc_unlikely (chunksize(p) != prevsize))
malloc_printerr ("corrupted size vs. prev_size in fastbins");
unlink_chunk (av, p);
}
if (nextchunk != av->top) {
nextinuse = inuse_bit_at_offset(nextchunk, nextsize);
if (!nextinuse) {
size += nextsize;
unlink_chunk (av, nextchunk);
} else
clear_inuse_bit_at_offset(nextchunk, 0);
first_unsorted = unsorted_bin->fd;
unsorted_bin->fd = p;
first_unsorted->bk = p;
if (!in_smallbin_range (size)) {
p->fd_nextsize = NULL;
p->bk_nextsize = NULL;
}
set_head(p, size | PREV_INUSE);
p->bk = unsorted_bin;
p->fd = first_unsorted;
set_foot(p, size);
}
else {
size += nextsize;
set_head(p, size | PREV_INUSE);
av->top = p;
}
} while ( (p = nextp) != 0);
}
} while (fb++ != maxfb);
}
/*
------------------------------ realloc ------------------------------
*/
void*
_int_realloc(mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
INTERNAL_SIZE_T nb)
{
mchunkptr newp; /* chunk to return */
INTERNAL_SIZE_T newsize; /* its size */
void* newmem; /* corresponding user mem */
mchunkptr next; /* next contiguous chunk after oldp */
mchunkptr remainder; /* extra space at end of newp */
unsigned long remainder_size; /* its size */
/* oldmem size */
if (__builtin_expect (chunksize_nomask (oldp) <= 2 * SIZE_SZ, 0)
|| __builtin_expect (oldsize >= av->system_mem, 0))
malloc_printerr ("realloc(): invalid old size");
check_inuse_chunk (av, oldp);
/* All callers already filter out mmap'ed chunks. */
assert (!chunk_is_mmapped (oldp));
next = chunk_at_offset (oldp, oldsize);
INTERNAL_SIZE_T nextsize = chunksize (next);
if (__builtin_expect (chunksize_nomask (next) <= 2 * SIZE_SZ, 0)
|| __builtin_expect (nextsize >= av->system_mem, 0))
malloc_printerr ("realloc(): invalid next size");
if ((unsigned long) (oldsize) >= (unsigned long) (nb))
{
/* already big enough; split below */
newp = oldp;
newsize = oldsize;
}
else
{
/* Try to expand forward into top */
if (next == av->top &&
(unsigned long) (newsize = oldsize + nextsize) >=
(unsigned long) (nb + MINSIZE))
{
set_head_size (oldp, nb | (av != &main_arena ? NON_MAIN_ARENA : 0));
av->top = chunk_at_offset (oldp, nb);
set_head (av->top, (newsize - nb) | PREV_INUSE);
check_inuse_chunk (av, oldp);
return chunk2mem (oldp);
}
/* Try to expand forward into next chunk; split off remainder below */
else if (next != av->top &&
!inuse (next) &&
(unsigned long) (newsize = oldsize + nextsize) >=
(unsigned long) (nb))
{
newp = oldp;
unlink_chunk (av, next);
}
/* allocate, copy, free */
else
{
newmem = _int_malloc (av, nb - MALLOC_ALIGN_MASK);
if (newmem == 0)
return 0; /* propagate failure */
newp = mem2chunk (newmem);
newsize = chunksize (newp);
/*
Avoid copy if newp is next chunk after oldp.
*/
if (newp == next)
{
newsize += oldsize;
newp = oldp;
}
else
{
memcpy (newmem, chunk2mem (oldp), oldsize - SIZE_SZ);
_int_free (av, oldp, 1);
check_inuse_chunk (av, newp);
return chunk2mem (newp);
}
}
}
/* If possible, free extra space in old or extended chunk */
assert ((unsigned long) (newsize) >= (unsigned long) (nb));
remainder_size = newsize - nb;
if (remainder_size < MINSIZE) /* not enough extra to split off */
{
set_head_size (newp, newsize | (av != &main_arena ? NON_MAIN_ARENA : 0));
set_inuse_bit_at_offset (newp, newsize);
}
else /* split remainder */
{
remainder = chunk_at_offset (newp, nb);
set_head_size (newp, nb | (av != &main_arena ? NON_MAIN_ARENA : 0));
set_head (remainder, remainder_size | PREV_INUSE |
(av != &main_arena ? NON_MAIN_ARENA : 0));
/* Mark remainder as inuse so free() won't complain */
set_inuse_bit_at_offset (remainder, remainder_size);
_int_free (av, remainder, 1);
}
check_inuse_chunk (av, newp);
return chunk2mem (newp);
}
/*
------------------------------ memalign ------------------------------
*/
static void *
_int_memalign (mstate av, size_t alignment, size_t bytes)
{
INTERNAL_SIZE_T nb; /* padded request size */
char *m; /* memory returned by malloc call */
mchunkptr p; /* corresponding chunk */
char *brk; /* alignment point within p */
mchunkptr newp; /* chunk to return */
INTERNAL_SIZE_T newsize; /* its size */
INTERNAL_SIZE_T leadsize; /* leading space before alignment point */
mchunkptr remainder; /* spare room at end to split off */
unsigned long remainder_size; /* its size */
INTERNAL_SIZE_T size;
checked_request2size (bytes, nb);
/*
Strategy: find a spot within that chunk that meets the alignment
request, and then possibly free the leading and trailing space.
*/
/* Check for overflow. */
if (nb > SIZE_MAX - alignment - MINSIZE)
{
__set_errno (ENOMEM);
return 0;
}
/* Call malloc with worst case padding to hit alignment. */
m = (char *) (_int_malloc (av, nb + alignment + MINSIZE));
if (m == 0)
return 0; /* propagate failure */
p = mem2chunk (m);
if ((((unsigned long) (m)) % alignment) != 0) /* misaligned */
{ /*
Find an aligned spot inside chunk. Since we need to give back
leading space in a chunk of at least MINSIZE, if the first
calculation places us at a spot with less than MINSIZE leader,
we can move to the next aligned spot -- we've allocated enough
total room so that this is always possible.
*/
brk = (char *) mem2chunk (((unsigned long) (m + alignment - 1)) &
- ((signed long) alignment));
if ((unsigned long) (brk - (char *) (p)) < MINSIZE)
brk += alignment;
newp = (mchunkptr) brk;
leadsize = brk - (char *) (p);
newsize = chunksize (p) - leadsize;
/* For mmapped chunks, just adjust offset */
if (chunk_is_mmapped (p))
{
set_prev_size (newp, prev_size (p) + leadsize);
set_head (newp, newsize | IS_MMAPPED);
return chunk2mem (newp);
}
/* Otherwise, give back leader, use the rest */
set_head (newp, newsize | PREV_INUSE |
(av != &main_arena ? NON_MAIN_ARENA : 0));
set_inuse_bit_at_offset (newp, newsize);
set_head_size (p, leadsize | (av != &main_arena ? NON_MAIN_ARENA : 0));
_int_free (av, p, 1);
p = newp;
assert (newsize >= nb &&
(((unsigned long) (chunk2mem (p))) % alignment) == 0);
}
/* Also give back spare room at the end */
if (!chunk_is_mmapped (p))
{
size = chunksize (p);
if ((unsigned long) (size) > (unsigned long) (nb + MINSIZE))
{
remainder_size = size - nb;
remainder = chunk_at_offset (p, nb);
set_head (remainder, remainder_size | PREV_INUSE |
(av != &main_arena ? NON_MAIN_ARENA : 0));
set_head_size (p, nb);
_int_free (av, remainder, 1);
}
}
check_inuse_chunk (av, p);
return chunk2mem (p);
}
/*
------------------------------ malloc_trim ------------------------------
*/
static int
mtrim (mstate av, size_t pad)
{
/* Ensure all blocks are consolidated. */
malloc_consolidate (av);
const size_t ps = GLRO (dl_pagesize);
int psindex = bin_index (ps);
const size_t psm1 = ps - 1;
int result = 0;
for (int i = 1; i < NBINS; ++i)
if (i == 1 || i >= psindex)
{
mbinptr bin = bin_at (av, i);
for (mchunkptr p = last (bin); p != bin; p = p->bk)
{
INTERNAL_SIZE_T size = chunksize (p);
if (size > psm1 + sizeof (struct malloc_chunk))
{
/* See whether the chunk contains at least one unused page. */
char *paligned_mem = (char *) (((uintptr_t) p
+ sizeof (struct malloc_chunk)
+ psm1) & ~psm1);
assert ((char *) chunk2mem (p) + 4 * SIZE_SZ <= paligned_mem);
assert ((char *) p + size > paligned_mem);
/* This is the size we could potentially free. */
size -= paligned_mem - (char *) p;
if (size > psm1)
{
#if MALLOC_DEBUG
/* When debugging we simulate destroying the memory
content. */
memset (paligned_mem, 0x89, size & ~psm1);
#endif
__madvise (paligned_mem, size & ~psm1, MADV_DONTNEED);
result = 1;
}
}
}
}
#ifndef MORECORE_CANNOT_TRIM
return result | (av == &main_arena ? systrim (pad, av) : 0);
#else
return result;
#endif
}
int
__malloc_trim (size_t s)
{
int result = 0;
if (__malloc_initialized < 0)
ptmalloc_init ();
mstate ar_ptr = &main_arena;
do
{
__libc_lock_lock (ar_ptr->mutex);
result |= mtrim (ar_ptr, s);
__libc_lock_unlock (ar_ptr->mutex);
ar_ptr = ar_ptr->next;
}
while (ar_ptr != &main_arena);
return result;
}
/*
------------------------- malloc_usable_size -------------------------
*/
static size_t
musable (void *mem)
{
mchunkptr p;
if (mem != 0)
{
p = mem2chunk (mem);
if (__builtin_expect (using_malloc_checking == 1, 0))
return malloc_check_get_size (p);
if (chunk_is_mmapped (p))
{
if (DUMPED_MAIN_ARENA_CHUNK (p))
return chunksize (p) - SIZE_SZ;
else
return chunksize (p) - 2 * SIZE_SZ;
}
else if (inuse (p))
return chunksize (p) - SIZE_SZ;
}
return 0;
}
size_t
__malloc_usable_size (void *m)
{
size_t result;
result = musable (m);
return result;
}
/*
------------------------------ mallinfo ------------------------------
Accumulate malloc statistics for arena AV into M.
*/
static void
int_mallinfo (mstate av, struct mallinfo *m)
{
size_t i;
mbinptr b;
mchunkptr p;
INTERNAL_SIZE_T avail;
INTERNAL_SIZE_T fastavail;
int nblocks;
int nfastblocks;
check_malloc_state (av);
/* Account for top */
avail = chunksize (av->top);
nblocks = 1; /* top always exists */
/* traverse fastbins */
nfastblocks = 0;
fastavail = 0;
for (i = 0; i < NFASTBINS; ++i)
{
for (p = fastbin (av, i); p != 0; p = p->fd)
{
++nfastblocks;
fastavail += chunksize (p);
}
}
avail += fastavail;
/* traverse regular bins */
for (i = 1; i < NBINS; ++i)
{
b = bin_at (av, i);
for (p = last (b); p != b; p = p->bk)
{
++nblocks;
avail += chunksize (p);
}
}
m->smblks += nfastblocks;
m->ordblks += nblocks;
m->fordblks += avail;
m->uordblks += av->system_mem - avail;
m->arena += av->system_mem;
m->fsmblks += fastavail;
if (av == &main_arena)
{
m->hblks = mp_.n_mmaps;
m->hblkhd = mp_.mmapped_mem;
m->usmblks = 0;
m->keepcost = chunksize (av->top);
}
}
struct mallinfo
__libc_mallinfo (void)
{
struct mallinfo m;
mstate ar_ptr;
if (__malloc_initialized < 0)
ptmalloc_init ();
memset (&m, 0, sizeof (m));
ar_ptr = &main_arena;
do
{
__libc_lock_lock (ar_ptr->mutex);
int_mallinfo (ar_ptr, &m);
__libc_lock_unlock (ar_ptr->mutex);
ar_ptr = ar_ptr->next;
}
while (ar_ptr != &main_arena);
return m;
}
/*
------------------------------ malloc_stats ------------------------------
*/
void
__malloc_stats (void)
{
int i;
mstate ar_ptr;
unsigned int in_use_b = mp_.mmapped_mem, system_b = in_use_b;
if (__malloc_initialized < 0)
ptmalloc_init ();
_IO_flockfile (stderr);
int old_flags2 = stderr->_flags2;
stderr->_flags2 |= _IO_FLAGS2_NOTCANCEL;
for (i = 0, ar_ptr = &main_arena;; i++)
{
struct mallinfo mi;
memset (&mi, 0, sizeof (mi));
__libc_lock_lock (ar_ptr->mutex);
int_mallinfo (ar_ptr, &mi);
fprintf (stderr, "Arena %d:\n", i);
fprintf (stderr, "system bytes = %10u\n", (unsigned int) mi.arena);
fprintf (stderr, "in use bytes = %10u\n", (unsigned int) mi.uordblks);
#if MALLOC_DEBUG > 1
if (i > 0)
dump_heap (heap_for_ptr (top (ar_ptr)));
#endif
system_b += mi.arena;
in_use_b += mi.uordblks;
__libc_lock_unlock (ar_ptr->mutex);
ar_ptr = ar_ptr->next;
if (ar_ptr == &main_arena)
break;
}
fprintf (stderr, "Total (incl. mmap):\n");
fprintf (stderr, "system bytes = %10u\n", system_b);
fprintf (stderr, "in use bytes = %10u\n", in_use_b);
fprintf (stderr, "max mmap regions = %10u\n", (unsigned int) mp_.max_n_mmaps);
fprintf (stderr, "max mmap bytes = %10lu\n",
(unsigned long) mp_.max_mmapped_mem);
stderr->_flags2 = old_flags2;
_IO_funlockfile (stderr);
}
/*
------------------------------ mallopt ------------------------------
*/
static __always_inline int
do_set_trim_threshold (size_t value)
{
LIBC_PROBE (memory_mallopt_trim_threshold, 3, value, mp_.trim_threshold,
mp_.no_dyn_threshold);
mp_.trim_threshold = value;
mp_.no_dyn_threshold = 1;
return 1;
}
static __always_inline int
do_set_top_pad (size_t value)
{
LIBC_PROBE (memory_mallopt_top_pad, 3, value, mp_.top_pad,
mp_.no_dyn_threshold);
mp_.top_pad = value;
mp_.no_dyn_threshold = 1;
return 1;
}
static __always_inline int
do_set_mmap_threshold (size_t value)
{
/* Forbid setting the threshold too high. */
if (value <= HEAP_MAX_SIZE / 2)
{
LIBC_PROBE (memory_mallopt_mmap_threshold, 3, value, mp_.mmap_threshold,
mp_.no_dyn_threshold);
mp_.mmap_threshold = value;
mp_.no_dyn_threshold = 1;
return 1;
}
return 0;
}
static __always_inline int
do_set_mmaps_max (int32_t value)
{
LIBC_PROBE (memory_mallopt_mmap_max, 3, value, mp_.n_mmaps_max,
mp_.no_dyn_threshold);
mp_.n_mmaps_max = value;
mp_.no_dyn_threshold = 1;
return 1;
}
static __always_inline int
do_set_mallopt_check (int32_t value)
{
return 1;
}
static __always_inline int
do_set_perturb_byte (int32_t value)
{
LIBC_PROBE (memory_mallopt_perturb, 2, value, perturb_byte);
perturb_byte = value;
return 1;
}
static __always_inline int
do_set_arena_test (size_t value)
{
LIBC_PROBE (memory_mallopt_arena_test, 2, value, mp_.arena_test);
mp_.arena_test = value;
return 1;
}
static __always_inline int
do_set_arena_max (size_t value)
{
LIBC_PROBE (memory_mallopt_arena_max, 2, value, mp_.arena_max);
mp_.arena_max = value;
return 1;
}
#if USE_TCACHE
static __always_inline int
do_set_tcache_max (size_t value)
{
if (value >= 0 && value <= MAX_TCACHE_SIZE)
{
LIBC_PROBE (memory_tunable_tcache_max_bytes, 2, value, mp_.tcache_max_bytes);
mp_.tcache_max_bytes = value;
mp_.tcache_bins = csize2tidx (request2size(value)) + 1;
}
return 1;
}
static __always_inline int
do_set_tcache_count (size_t value)
{
LIBC_PROBE (memory_tunable_tcache_count, 2, value, mp_.tcache_count);
mp_.tcache_count = value;
return 1;
}
static __always_inline int
do_set_tcache_unsorted_limit (size_t value)
{
LIBC_PROBE (memory_tunable_tcache_unsorted_limit, 2, value, mp_.tcache_unsorted_limit);
mp_.tcache_unsorted_limit = value;
return 1;
}
#endif
int
__libc_mallopt (int param_number, int value)
{
mstate av = &main_arena;
int res = 1;
if (__malloc_initialized < 0)
ptmalloc_init ();
__libc_lock_lock (av->mutex);
LIBC_PROBE (memory_mallopt, 2, param_number, value);
/* We must consolidate main arena before changing max_fast
(see definition of set_max_fast). */
malloc_consolidate (av);
switch (param_number)
{
case M_MXFAST:
if (value >= 0 && value <= MAX_FAST_SIZE)
{
LIBC_PROBE (memory_mallopt_mxfast, 2, value, get_max_fast ());
set_max_fast (value);
}
else
res = 0;
break;
case M_TRIM_THRESHOLD:
do_set_trim_threshold (value);
break;
case M_TOP_PAD:
do_set_top_pad (value);
break;
case M_MMAP_THRESHOLD:
res = do_set_mmap_threshold (value);
break;
case M_MMAP_MAX:
do_set_mmaps_max (value);
break;
case M_CHECK_ACTION:
do_set_mallopt_check (value);
break;
case M_PERTURB:
do_set_perturb_byte (value);
break;
case M_ARENA_TEST:
if (value > 0)
do_set_arena_test (value);
break;
case M_ARENA_MAX:
if (value > 0)
do_set_arena_max (value);
break;
}
__libc_lock_unlock (av->mutex);
return res;
}
libc_hidden_def (__libc_mallopt)
/*
-------------------- Alternative MORECORE functions --------------------
*/
/*
General Requirements for MORECORE.
The MORECORE function must have the following properties:
If MORECORE_CONTIGUOUS is false:
* MORECORE must allocate in multiples of pagesize. It will
only be called with arguments that are multiples of pagesize.
* MORECORE(0) must return an address that is at least
MALLOC_ALIGNMENT aligned. (Page-aligning always suffices.)
else (i.e. If MORECORE_CONTIGUOUS is true):
* Consecutive calls to MORECORE with positive arguments
return increasing addresses, indicating that space has been
contiguously extended.
* MORECORE need not allocate in multiples of pagesize.
Calls to MORECORE need not have args of multiples of pagesize.
* MORECORE need not page-align.
In either case:
* MORECORE may allocate more memory than requested. (Or even less,
but this will generally result in a malloc failure.)
* MORECORE must not allocate memory when given argument zero, but
instead return one past the end address of memory from previous
nonzero call. This malloc does NOT call MORECORE(0)
until at least one call with positive arguments is made, so
the initial value returned is not important.
* Even though consecutive calls to MORECORE need not return contiguous
addresses, it must be OK for malloc'ed chunks to span multiple
regions in those cases where they do happen to be contiguous.
* MORECORE need not handle negative arguments -- it may instead
just return MORECORE_FAILURE when given negative arguments.
Negative arguments are always multiples of pagesize. MORECORE
must not misinterpret negative args as large positive unsigned
args. You can suppress all such calls from even occurring by defining
MORECORE_CANNOT_TRIM,
There is some variation across systems about the type of the
argument to sbrk/MORECORE. If size_t is unsigned, then it cannot
actually be size_t, because sbrk supports negative args, so it is
normally the signed type of the same width as size_t (sometimes
declared as "intptr_t", and sometimes "ptrdiff_t"). It doesn't much
matter though. Internally, we use "long" as arguments, which should
work across all reasonable possibilities.
Additionally, if MORECORE ever returns failure for a positive
request, then mmap is used as a noncontiguous system allocator. This
is a useful backup strategy for systems with holes in address spaces
-- in this case sbrk cannot contiguously expand the heap, but mmap
may be able to map noncontiguous space.
If you'd like mmap to ALWAYS be used, you can define MORECORE to be
a function that always returns MORECORE_FAILURE.
If you are using this malloc with something other than sbrk (or its
emulation) to supply memory regions, you probably want to set
MORECORE_CONTIGUOUS as false. As an example, here is a custom
allocator kindly contributed for pre-OSX macOS. It uses virtually
but not necessarily physically contiguous non-paged memory (locked
in, present and won't get swapped out). You can use it by
uncommenting this section, adding some #includes, and setting up the
appropriate defines above:
*#define MORECORE osMoreCore
*#define MORECORE_CONTIGUOUS 0
There is also a shutdown routine that should somehow be called for
cleanup upon program exit.
*#define MAX_POOL_ENTRIES 100
*#define MINIMUM_MORECORE_SIZE (64 * 1024)
static int next_os_pool;
void *our_os_pools[MAX_POOL_ENTRIES];
void *osMoreCore(int size)
{
void *ptr = 0;
static void *sbrk_top = 0;
if (size > 0)
{
if (size < MINIMUM_MORECORE_SIZE)
size = MINIMUM_MORECORE_SIZE;
if (CurrentExecutionLevel() == kTaskLevel)
ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0);
if (ptr == 0)
{
return (void *) MORECORE_FAILURE;
}
// save ptrs so they can be freed during cleanup
our_os_pools[next_os_pool] = ptr;
next_os_pool++;
ptr = (void *) ((((unsigned long) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK);
sbrk_top = (char *) ptr + size;
return ptr;
}
else if (size < 0)
{
// we don't currently support shrink behavior
return (void *) MORECORE_FAILURE;
}
else
{
return sbrk_top;
}
}
// cleanup any allocated memory pools
// called as last thing before shutting down driver
void osCleanupMem(void)
{
void **ptr;
for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++)
if (*ptr)
{
PoolDeallocate(*ptr);
* ptr = 0;
}
}
*/
/* Helper code. */
extern char **__libc_argv attribute_hidden;
static void
malloc_printerr (const char *str)
{
__libc_message (do_abort, "%s\n", str);
__builtin_unreachable ();
}
/* We need a wrapper function for one of the additions of POSIX. */
int
__posix_memalign (void **memptr, size_t alignment, size_t size)
{
void *mem;
/* Test whether the SIZE argument is valid. It must be a power of
two multiple of sizeof (void *). */
if (alignment % sizeof (void *) != 0
|| !powerof2 (alignment / sizeof (void *))
|| alignment == 0)
return EINVAL;
void *address = RETURN_ADDRESS (0);
mem = _mid_memalign (alignment, size, address);
if (mem != NULL)
{
*memptr = mem;
return 0;
}
return ENOMEM;
}
weak_alias (__posix_memalign, posix_memalign)
int
__malloc_info (int options, FILE *fp)
{
/* For now, at least. */
if (options != 0)
return EINVAL;
int n = 0;
size_t total_nblocks = 0;
size_t total_nfastblocks = 0;
size_t total_avail = 0;
size_t total_fastavail = 0;
size_t total_system = 0;
size_t total_max_system = 0;
size_t total_aspace = 0;
size_t total_aspace_mprotect = 0;
if (__malloc_initialized < 0)
ptmalloc_init ();
fputs ("<malloc version=\"1\">\n", fp);
/* Iterate over all arenas currently in use. */
mstate ar_ptr = &main_arena;
do
{
fprintf (fp, "<heap nr=\"%d\">\n<sizes>\n", n++);
size_t nblocks = 0;
size_t nfastblocks = 0;
size_t avail = 0;
size_t fastavail = 0;
struct
{
size_t from;
size_t to;
size_t total;
size_t count;
} sizes[NFASTBINS + NBINS - 1];
#define nsizes (sizeof (sizes) / sizeof (sizes[0]))
__libc_lock_lock (ar_ptr->mutex);
for (size_t i = 0; i < NFASTBINS; ++i)
{
mchunkptr p = fastbin (ar_ptr, i);
if (p != NULL)
{
size_t nthissize = 0;
size_t thissize = chunksize (p);
while (p != NULL)
{
++nthissize;
p = p->fd;
}
fastavail += nthissize * thissize;
nfastblocks += nthissize;
sizes[i].from = thissize - (MALLOC_ALIGNMENT - 1);
sizes[i].to = thissize;
sizes[i].count = nthissize;
}
else
sizes[i].from = sizes[i].to = sizes[i].count = 0;
sizes[i].total = sizes[i].count * sizes[i].to;
}
mbinptr bin;
struct malloc_chunk *r;
for (size_t i = 1; i < NBINS; ++i)
{
bin = bin_at (ar_ptr, i);
r = bin->fd;
sizes[NFASTBINS - 1 + i].from = ~((size_t) 0);
sizes[NFASTBINS - 1 + i].to = sizes[NFASTBINS - 1 + i].total
= sizes[NFASTBINS - 1 + i].count = 0;
if (r != NULL)
while (r != bin)
{
size_t r_size = chunksize_nomask (r);
++sizes[NFASTBINS - 1 + i].count;
sizes[NFASTBINS - 1 + i].total += r_size;
sizes[NFASTBINS - 1 + i].from
= MIN (sizes[NFASTBINS - 1 + i].from, r_size);
sizes[NFASTBINS - 1 + i].to = MAX (sizes[NFASTBINS - 1 + i].to,
r_size);
r = r->fd;
}
if (sizes[NFASTBINS - 1 + i].count == 0)
sizes[NFASTBINS - 1 + i].from = 0;
nblocks += sizes[NFASTBINS - 1 + i].count;
avail += sizes[NFASTBINS - 1 + i].total;
}
size_t heap_size = 0;
size_t heap_mprotect_size = 0;
size_t heap_count = 0;
if (ar_ptr != &main_arena)
{
/* Iterate over the arena heaps from back to front. */
heap_info *heap = heap_for_ptr (top (ar_ptr));
do
{
heap_size += heap->size;
heap_mprotect_size += heap->mprotect_size;
heap = heap->prev;
++heap_count;
}
while (heap != NULL);
}
__libc_lock_unlock (ar_ptr->mutex);
total_nfastblocks += nfastblocks;
total_fastavail += fastavail;
total_nblocks += nblocks;
total_avail += avail;
for (size_t i = 0; i < nsizes; ++i)
if (sizes[i].count != 0 && i != NFASTBINS)
fprintf (fp, " \
<size from=\"%zu\" to=\"%zu\" total=\"%zu\" count=\"%zu\"/>\n",
sizes[i].from, sizes[i].to, sizes[i].total, sizes[i].count);
if (sizes[NFASTBINS].count != 0)
fprintf (fp, "\
<unsorted from=\"%zu\" to=\"%zu\" total=\"%zu\" count=\"%zu\"/>\n",
sizes[NFASTBINS].from, sizes[NFASTBINS].to,
sizes[NFASTBINS].total, sizes[NFASTBINS].count);
total_system += ar_ptr->system_mem;
total_max_system += ar_ptr->max_system_mem;
fprintf (fp,
"</sizes>\n<total type=\"fast\" count=\"%zu\" size=\"%zu\"/>\n"
"<total type=\"rest\" count=\"%zu\" size=\"%zu\"/>\n"
"<system type=\"current\" size=\"%zu\"/>\n"
"<system type=\"max\" size=\"%zu\"/>\n",
nfastblocks, fastavail, nblocks, avail,
ar_ptr->system_mem, ar_ptr->max_system_mem);
if (ar_ptr != &main_arena)
{
fprintf (fp,
"<aspace type=\"total\" size=\"%zu\"/>\n"
"<aspace type=\"mprotect\" size=\"%zu\"/>\n"
"<aspace type=\"subheaps\" size=\"%zu\"/>\n",
heap_size, heap_mprotect_size, heap_count);
total_aspace += heap_size;
total_aspace_mprotect += heap_mprotect_size;
}
else
{
fprintf (fp,
"<aspace type=\"total\" size=\"%zu\"/>\n"
"<aspace type=\"mprotect\" size=\"%zu\"/>\n",
ar_ptr->system_mem, ar_ptr->system_mem);
total_aspace += ar_ptr->system_mem;
total_aspace_mprotect += ar_ptr->system_mem;
}
fputs ("</heap>\n", fp);
ar_ptr = ar_ptr->next;
}
while (ar_ptr != &main_arena);
fprintf (fp,
"<total type=\"fast\" count=\"%zu\" size=\"%zu\"/>\n"
"<total type=\"rest\" count=\"%zu\" size=\"%zu\"/>\n"
"<total type=\"mmap\" count=\"%d\" size=\"%zu\"/>\n"
"<system type=\"current\" size=\"%zu\"/>\n"
"<system type=\"max\" size=\"%zu\"/>\n"
"<aspace type=\"total\" size=\"%zu\"/>\n"
"<aspace type=\"mprotect\" size=\"%zu\"/>\n"
"</malloc>\n",
total_nfastblocks, total_fastavail, total_nblocks, total_avail,
mp_.n_mmaps, mp_.mmapped_mem,
total_system, total_max_system,
total_aspace, total_aspace_mprotect);
return 0;
}
weak_alias (__malloc_info, malloc_info)
strong_alias (__libc_calloc, __calloc) weak_alias (__libc_calloc, calloc)
strong_alias (__libc_free, __free) strong_alias (__libc_free, free)
strong_alias (__libc_malloc, __malloc) strong_alias (__libc_malloc, malloc)
strong_alias (__libc_memalign, __memalign)
weak_alias (__libc_memalign, memalign)
strong_alias (__libc_realloc, __realloc) strong_alias (__libc_realloc, realloc)
strong_alias (__libc_valloc, __valloc) weak_alias (__libc_valloc, valloc)
strong_alias (__libc_pvalloc, __pvalloc) weak_alias (__libc_pvalloc, pvalloc)
strong_alias (__libc_mallinfo, __mallinfo)
weak_alias (__libc_mallinfo, mallinfo)
strong_alias (__libc_mallopt, __mallopt) weak_alias (__libc_mallopt, mallopt)
weak_alias (__malloc_stats, malloc_stats)
weak_alias (__malloc_usable_size, malloc_usable_size)
weak_alias (__malloc_trim, malloc_trim)
#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_26)
compat_symbol (libc, __libc_free, cfree, GLIBC_2_0);
#endif
/* ------------------------------------------------------------
History:
[see ftp://g.oswego.edu/pub/misc/malloc.c for the history of dlmalloc]
*/
/*
* Local variables:
* c-basic-offset: 2
* End:
*/
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