elf_version(3E)           UNIX System V(ELF Library)            elf_version(3E)


NAME
      elfversion - coordinate ELF library and application versions

SYNOPSIS
      cc [flag ...] file ...  -lelf [library ...]

      #include <libelf.h>
      unsigned elfversion(unsigned ver);

DESCRIPTION
      As elf(3E) explains, the program, the library, and an object file have
      independent notions of the ``latest'' ELF version.  elfversion lets a
      program determine the ELF library's internal version.  It further lets
      the program specify what memory types it uses by giving its own working
      version, ver, to the library.  Every program that uses the ELF library
      must coordinate versions as described below.

      The header file <libelf.h> supplies the version to the program with the
      macro EVCURRENT.  If the library's internal version (the highest version
      known to the library) is lower than that known by the program itself, the
      library may lack semantic knowledge assumed by the program.  Accordingly,
      elfversion will not accept a working version unknown to the library.

      Passing ver equal to EVNONE causes elfversion to return the library's
      internal version, without altering the working version.  If ver is a
      version known to the library, elfversion returns the previous (or
      initial) working version number.  Otherwise, the working version remains
      unchanged and elfversion returns EVNONE.

EXAMPLE
      The following excerpt from an application program protects itself from
      using an older library.

           if (elfversion(EVCURRENT) == EVNONE)
           {
                   /* library out of date */
                   /* recover from error */
           }

NOTES
      The working version should be the same for all operations on a particular
      elf descriptor.  Changing the version between operations on a descriptor
      will probably not give the expected results.

SEE ALSO
      elf(3E), elfbegin(3E), elfxlate(3E)








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