drop into the debugger on exception IFF being debugged

amibeingdebugged.c

//
//  amibeingdebugged.c
//  HSILibs
//
// based on:  https://developer.apple.com/library/mac/qa/qa1361/_index.html
//

#include <assert.h>
#include <stdbool.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/sysctl.h>
#include <signal.h>

#include "amibeingdebugged.h"

// Returns true if the current process is being debugged (either
// running under the debugger or has a debugger attached post facto).
bool AmIBeingDebugged( void )
{
    int                 junk;
    int                 mib[4];
    struct kinfo_proc   info;
    size_t              size;
    
    // Initialize the flags so that, if sysctl fails for some bizarre
    // reason, we get a predictable result.
    
    info.kp_proc.p_flag = 0;
    
    // Initialize mib, which tells sysctl the info we want, in this case
    // we're looking for information about a specific process ID.
    
    mib[0] = CTL_KERN;
    mib[1] = KERN_PROC;
    mib[2] = KERN_PROC_PID;
    mib[3] = getpid();
    
    // Call sysctl.
    
    size = sizeof(info);
    junk = sysctl(mib, sizeof(mib) / sizeof(*mib), &info, &size, NULL, 0);
    assert(junk == 0);
    
    // We're being debugged if the P_TRACED flag is set.
    
    return ( (info.kp_proc.p_flag & P_TRACED) != 0 );
}



#if DEBUG
void dRaiseSIGINT( void )
{
    if ( AmIBeingDebugged() )
        raise( SIGINT );
}
#endif

amibeingdebugged.h

//
//  amibeingdebugged.h
//  HSILibs
//
//  Copyright (c) 2013 Haiku Software, Inc. All rights reserved.
//

#ifndef HSI_amibeingdebugged_h
#define HSI_amibeingdebugged_h


extern bool AmIBeingDebugged( void );

#if defined(DEBUG) && (DEBUG == 1)
    extern void dRaiseSIGINT( void );
#else
    #define dRaiseSIGINT( void )    
#endif


#if defined(DEBUG) && (DEBUG == 1)
    #define dASSERT_RAISE( cond, objCformatStr, var_args1... )     do { if (!(cond)) { NSLog( objCformatStr, ## var_args1 ); dRaiseSIGINT(); } } while (0)
#else
    #define dASSERT_RAISE( cond, objCformatStr, var_args1... )
#endif

#endif