ELF_VERSION(3ELF) ELF Library Functions ELF_VERSION(3ELF)

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(3ELF) explains, the program, the library, and an object file
have independent notions of the latest ELF version. elf_version()
lets a program query 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 <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

Example 1: A sample display of using the elf_version() function.

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/* library out of date */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 */
}

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Stable |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO

elf(3ELF), elf32_xlatetof(3ELF), elf_begin(3ELF), libelf(3LIB),
attributes(7)

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.

July 11, 2001 ELF_VERSION(3ELF)