NAME
elf_version — coordinate ELF library and application versions
SYNOPSIS
cc
[flag... ]
file...
-lelf
[library]...
#include
<libelf.h>
unsigned elf_version(unsigned ver);
DESCRIPTION
As
elf(3E)
explains, the program, the library, and an object
file have independent notions of the ``latest'' ELF version.
elf_version
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
EV_CURRENT.
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,
elf_version
will not accept a working version unknown to the library.
Passing
ver
equal to
EV_NONE
causes
elf_version
to return the
library's internal version, without altering the working
version. If
ver
is a version known to the library,
elf_version
returns the previous (or initial) working version
number. Otherwise, the working version remains unchanged and
elf_version
returns
EV_NONE.
EXAMPLES
The following excerpt from an application program protects
itself from using an older library.
if (elf_version(EV_CURRENT) == EV_NONE)
{
/* library out of date */
/* recover from error */
}
NOTICES
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.