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/* library out of date */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(5) 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(5)

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)