CMake macro to detect glibc version by filename.

glibc.cmake

# - Check glibc version
# CHECK_GLIBC_VERSION()
# 
# Once done this will define
#
#   GLIBC_VERSION - glibc version
#
MACRO (CHECK_GLIBC_VERSION)
    EXECUTE_PROCESS (
        COMMAND ${CMAKE_C_COMPILER} -print-file-name=libc.so.6
	OUTPUT_VARIABLE GLIBC
	OUTPUT_STRIP_TRAILING_WHITESPACE)

    GET_FILENAME_COMPONENT (GLIBC ${GLIBC} REALPATH)
    GET_FILENAME_COMPONENT (GLIBC_VERSION ${GLIBC} NAME)
    STRING (REPLACE "libc-" "" GLIBC_VERSION ${GLIBC_VERSION})
    STRING (REPLACE ".so" "" GLIBC_VERSION ${GLIBC_VERSION})
    IF (NOT GLIBC_VERSION MATCHES "^[0-9.]+$")
        MESSAGE (FATAL_ERROR "Unknown glibc version: ${GLIBC_VERSION}")
    ENDIF (NOT GLIBC_VERSION MATCHES "^[0-9.]+$")
ENDMACRO (CHECK_GLIBC_VERSION)

Check glibc version if it is composed of 0, ..., 9 and .

This will fail if the base file is libc.so.6 ... which it often is.

This will fail if the base file is libc.so.6 ... which it often is.

What do you mean?

What do you mean?

I mean, that the filename doesn't include the glibc version - and this module assumes that it does and tries to parse the name to get the version.

Any suggestions ?

Well, one thing which often works - not sure whether it always works - is run libc.so.6. Yes, it's typically executable - and prints version information.

It seems STRING (REPLACE "libc-" "" GLIBC_VERSION ${GLIBC_VERSION}) causes the problem.
I resolved this by removing the dash character like STRING (REPLACE "libc" "" GLIBC_VERSION ${GLIBC_VERSION}).
I'm not sure whether this is acceptable for all versions of GLIBC.

It seems STRING (REPLACE "libc-" "" GLIBC_VERSION ${GLIBC_VERSION}) causes the problem. I resolved this by removing the dash character like STRING (REPLACE "libc" "" GLIBC_VERSION ${GLIBC_VERSION}). I'm not sure whether this is acceptable for all versions of GLIBC.

Which distribution is your OS ? Ubuntu or Redhat ?

Can you show me ?

realpath `gcc -print-file-name=libc.so.6`

Well, one thing which often works - not sure whether it always works - is run libc.so.6. Yes, it's typically executable - and prints version information.

It does not work for cross compiler, such as aarch64

Maybe you can implement CMake macro like

objdump -T `gcc -print-file-name=libc.so.6` \
  | grep -o 'GLIBC_[0-9]\+\(\.[0-9]\+\)*' \
  | sort -ruV \
  | head -1

Well, one thing which often works - not sure whether it always works - is run libc.so.6. Yes, it's typically executable - and prints version information.

It does not work for cross compiler, such as aarch64

Maybe you can implement CMake macro like

objdump -T `gcc -print-file-name=libc.so.6` \
  | grep -o 'GLIBC_[0-9]\+\(\.[0-9]\+\)*' \
  | sort -ruV \
  | head -1

realpath `gcc -print-file-name=libc.so.6`
/usr/lib/x86_64-linux-gnu/libc.so.6

Or adding one more line would be fine, like this.

MACRO (CHECK_GLIBC_VERSION)
    EXECUTE_PROCESS (
        COMMAND ${CMAKE_C_COMPILER} -print-file-name=libc.so.6
	OUTPUT_VARIABLE GLIBC
	OUTPUT_STRIP_TRAILING_WHITESPACE)

    GET_FILENAME_COMPONENT (GLIBC ${GLIBC} REALPATH)
    GET_FILENAME_COMPONENT (GLIBC_VERSION ${GLIBC} NAME)
    STRING (REPLACE "libc-" "" GLIBC_VERSION ${GLIBC_VERSION})
    STRING (REPLACE "libc" "" GLIBC_VERSION ${GLIBC_VERSION})  # added
    STRING (REPLACE ".so" "" GLIBC_VERSION ${GLIBC_VERSION})
    IF (NOT GLIBC_VERSION MATCHES "^[0-9.]+$")
        MESSAGE (FATAL_ERROR "Unknown glibc version: ${GLIBC_VERSION}")
    ENDIF (NOT GLIBC_VERSION MATCHES "^[0-9.]+$")
ENDMACRO (CHECK_GLIBC_VERSION)

Even added this line, it seems that only the major version of glibc can be extracted

MACRO (CHECK_GLIBC_VERSION)
	message("Checking GLIBC Version.")
	EXECUTE_PROCESS (
		COMMAND ${CMAKE_C_COMPILER} -print-file-name=libc.so.6
		OUTPUT_VARIABLE GLIBC
		OUTPUT_STRIP_TRAILING_WHITESPACE)

	GET_FILENAME_COMPONENT (GLIBC ${GLIBC} REALPATH)
	EXECUTE_PROCESS (
		COMMAND ${GLIBC}
		OUTPUT_VARIABLE GLIBC_OUTPUT
		ERROR_QUIET
		OUTPUT_STRIP_TRAILING_WHITESPACE)
	STRING (REGEX MATCH "release version ([0-9]+\\.[0-9]+)" GLIBC_VERSION ${GLIBC_OUTPUT})
	STRING (REPLACE "release version " "" GLIBC_VERSION ${GLIBC_VERSION})
	IF (NOT GLIBC_VERSION MATCHES "^[0-9.]+$")
		MESSAGE (FATAL_ERROR "Unknown glibc version: ${GLIBC_VERSION}")
	ENDIF (NOT GLIBC_VERSION MATCHES "^[0-9.]+$")
ENDMACRO (CHECK_GLIBC_VERSION)