elf_getident(3ELF) ELF Library Functions elf_getident(3ELF)NAME
elf_getident, elf_getshnum, elf_getshstrndx - retrieve ELF header data
SYNOPSIS
cc [ flag ... ] file ... -lelf [ library ... ]
#include <libelf.h>
char * elf_getident(Elf *elf, size_t *dst);
int elf_getshnum(Elf *elf, size_t *dst);
int elf_getshstrndx(Elf *elf, size_t *dst);
DESCRIPTION
As elf(3ELF) explains, ELF provides a framework for various classes of
files, where basic objects may have 32 bits, 64 bits, etc. To accommo‐
date these differences, without forcing the larger sizes on smaller
machines, the initial bytes in an ELF file hold identification informa‐
tion common to all file classes. Every ELF header's e_ident has
EI_NIDENT bytes with the following interpretation:
e_ident Index Value Purpose
EI_MAG0 ELFMAG0 File identification
EI_MAG1 ELFMAG1
EI_MAG2 ELFMAG2
EI_MAG3 ELFMAG3
EI_CLASS ELFCLASSNONE File class
ELFCLASS32
ELFCLASS64
EI_DATA ELFDATANONE Data encoding
ELFDATA2LSB
ELFDATA2MSB
EI_VERSION EV_CURRENT File version
7-15 0 Unused, set to zero
Other kinds of files (see elf_kind(3ELF)) also may have identification
data, though they would not conform to e_ident.
elf_getident() returns a pointer to the file's ``initial bytes.'' If
the library recognizes the file, a conversion from the file image to
the memory image may occur. In any case, the identification bytes are
guaranteed not to have been modified, though the size of the unmodified
area depends on the file type. If dst is non-null, the library stores
the number of identification bytes in the location to which dst points.
If no data are present, elf is null, or an error occurs, the return
value is a null pointer, with 0 stored through dst, if dst is non-null.
The elf_getshnum() function obtains the number of sections recorded in
the ELF file. The number of sections in a file is typically recorded in
the e_shnum field of the ELF header, though a file that requires ELF
Extended Sections records the value 0 in the e_shnum field and records
the number of sections in the sh_size field of section header 0. See
USAGE. dst points to the location where the number of sections will be
stored. If a call to elf_newscn(3ELF) using the same elf descriptor has
been performed, then the value obtained by elf_getshnum() is only valid
after a successful call to elf_update(3ELF). If elf is NULL or an error
occurs, elf_getshnum() returns -1.
The elf_getshstrndx() function obtains the section index of the string
table associated with the section headers in the ELF file. The section
header string table index is typically recorded in the e_shstrndx field
of the ELF header, though a file that requires ELF Extended Sections
records the value SHN_XINDEX in the e_shstrndx field and records the
string table index in the sh_link field of section header 0. See USAGE.
The dst argument points to the location where the section header string
table index is stored. If elf is NULL or an error occurs, elf_get‐
shstrndx() returns -1.
USAGE
ELF Extended Sections are employed to allow an ELF file to contain more
than 0xff00 (SHN_LORESERVE) section. See the Linker and Libraries Guide
for more information.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Stable │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOelf(3ELF), elf32_getehdr(3ELF), elf_begin(3ELF), elf_kind(3ELF),
elf_newscn(3ELF), elf_rawfile(3ELF), elf_update(3ELF), libelf(3LIB),
attributes(5)
Linker and Libraries Guide
SunOS 5.10 20 Jun 2002 elf_getident(3ELF)
