.TH ELF_GETIDENT 3 2025-06-30 "Libelf" "Libelf Programmer's Manual"

.SH NAME
elf_getident \- return the ELF identification bytes
.SH SYNOPSIS
.nf
#include <libelf.h>

.B char * elf_getident("Elf *elf", "size_t *nbytes");
.fi
.SH DESCRIPTION
The
.BR elf_getident ()
function returns a pointer to the 16-byte ELF identification array
from the ELF header of the given descriptor
.IR elf .

This identification data begins with the magic number `\fB\\177ELF\fR`
and includes the class, data encoding, ELF version, OS ABI, and ABI
version fields. It corresponds to the first
.B EI_NIDENT
bytes of the ELF header and can be accessed via the
.B e_ident
field of either
.B Elf32_Ehdr
or
.B Elf64_Ehdr .

If
.I elf
is a valid descriptor for an ELF object, the function returns a pointer to
the internal buffer containing the header's identification bytes. The buffer
is owned by the library and must not be modified or freed by the caller.

If
.I nbytes 
is not NULL, the function sets
.*nbytes
to
.B EI_NIDENT
(16), the length in bytes of the returned identifier.

.SH PARAMETERS
.TP
.I elf
Pointer to an
.B Elf
descriptor referring to a valid ELF object.  If the descriptor does not
represent an ELF object file (is NULL or
.BR elf_kind ()
is not
.B ELF_K_ELF
), NULL is returned.

.TP
.I nbytes
Optional pointer to a
.B size_t
variable. If non-NULL, it will be set to the length of the returned buffer
(always EI_NIDENT on success, 0 on failure).

.SH RETURN VALUE
Returns a pointer to the internal 16-byte
.B e_ident
buffer on success and NULL on failure.  Does not set elf_errno.

This buffer is indexed using the
.BR EI_CLASS ,
.BR EI_DATA ,
.BR EI_VERSION ,
.BR EI_OSABI ,
and
.BR EI_ABIVERSION
macros found in elf.h.  Also see
.BR elf (5).

.SH SEE ALSO
.BR libelf (3),
.BR elf (5)

.SH ATTRIBUTES
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.na
.nh
.BR elf_getident ()
T}	Thread safety	MT-Safe
.TE

.SH REPORTING BUGS
Report bugs to <elfutils-devel@sourceware.org> or https://sourceware.org/bugzilla/.