.TH GELF_CHECKSUM 3 2025-12-31 "Libelf" "Libelf Programmer's Manual"

.SH NAME
gelf_checksum \- compute the checksum for an ELF object file

.SH SYNOPSIS
.nf
.B #include <gelf.h>

.BI "long int gelf_checksum (Elf *" elf ");"

.SH DESCRIPTION
Compute a checksum for the ELF object file referred to by
.IR elf .
This function acts as a wrapper around
.BR elf32_checksum ()
and
.BR elf64_checksum ().
The binary class of
.I elf
is used to automatically select between
.BR elf32_checksum ()
and
.BR elf64_checksum ().

The checksum is computed from permanent parts of the ELF file and
the result is repeatable.  To be repeatable, strippable sections are
not included in computing the checksum.
.B SHT_NOBITS
sections are also not included when computing the checksum.  The checksum
can be used as a value for
.BR DT_CHECKSUM .

.SH PARAMETERS
.TP
.I elf
The ELF object file for which the checksum is to be computed.

.SH RETURN VALUE
On success, return the computed checksum. On failure, return -1
and set elf_errno.  If
.I elf
is NULL then -1 is returned without setting elf_errno.

The checksum is always calculated as a 4-byte value. If
.I long int
is larger than 4 bytes, then the checksum will be extended by padding
with zeros.

.SH SEE ALSO
.BR elf32_checksum (3),
.BR elf64_checksum (3),
.BR libelf (3),
.BR elf (5)

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

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