.TH GELF_UPDATE_SYM 3 2025-09-07 "Libelf" "Libelf Programmer's Manual"

.SH NAME
gelf_update_sym \- update a class\-independent symbol table entry

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

.BI "int gelf_update_sym (Elf_Data *" data ", int " ndx ", GElf_Sym *" src ");"

.SH DESCRIPTION
Copy a class\-independent symbol table entry from
.I src
into the
.B SHT_SYMTAB
or
.B SHT_DYNSYM
section associated with
.I data
at entry index
.IR ndx .

The number of symbols in the symbol table can be calculated by dividing the
size of the corresponding section (\fBsh_size\fP or \fBd_size\fP)
by the size of a symbol table entry.  The size of a symbol table entry can be
obtained from
.B sh_entsize
or
.BR gelf_fsize (3).

If the corresponding ELF file contains more than 64K sections then
.BR gelf_update_symshndx
should be used to update a symbol's section index in an extended section
index table.  See
.BR gelf_update_symshndx (3)
for more information.


.SH PARAMETERS
.TP
.I data
.B Elf_Data for a symbol table section with type
.B SHT_SYMTAB
or
.BR SHT_DYNSYM .

.TP
.I ndx
Zero\-based index of the symbol table entry to be updated within
.IR data .

.TP
.I src
Pointer to the caller\-provided symbol table entry.  For
.B ELFCLASS32
binaries,
.B st_value
and
.B st_size
should be able to fit within unsigned 32-bit values.
.I src
must not be NULL.

.SH RETURN VALUE
On success, this function returns a non-zero value and updates
the symbol table entry at index
.I ndx
in
.IR data .
The symbol table section associated with
.I data
will be flagged with
.BR ELF_F_DIRTY .
On failure, zero is returned and elf_errno is set.  If
.I data
is NULL, then zero is returned and elf_errno is not set.

.SH SEE ALSO
.BR gelf_getsym (3),
.BR gelf_update_symshndx (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_update_sym ()
T}	Thread safety	MT-Safe
.TE

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