.TH GELF_UPDATE_PHDR 3 2025-12-27 "Libelf" "Libelf Programmer's Manual"

.SH NAME
gelf_update_phdr \- copy a class\-independent program header table entry into an ELF descriptor

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

.BI "int gelf_update_phdr (Elf *" elf ", int " ndx ", GElf_Phdr *" src ");"

.SH DESCRIPTION
.BR gelf_update_phdr ()
copies the class\-independent program header table entry from the structure
pointed to by
.I src
into the program header table of
.I elf
at index
.I ndx .
The program header table entry is translated as necessary to match the class
(\fBELFCLASS32\fP or \fBELFCLASS64\fP) of the underlying object file.

If
.I elf
has class
.B ELFCLASS32
then
.BR p_offset ,
.BR p_vaddr ,
.BR p_paddr ,
.BR p_filesz ,
.BR p_memsz ,
and
.B p_align
must fit within unsigned 32-bit values.

.SH PARAMETERS
.TP
.I elf
Pointer to an ELF descriptor of kind
.BR ELF_K_ELF .

.TP
.I ndx
Index of the program header table entry to be updated.  The number of program
header table entries associated with
.I elf
can be obtained with
.BR elf_getphdrnum ().

.TP
.I src
Pointer to a
.B GElf_Phdr
structure that holds the caller's desired program header table entry contents.
.I src
must not be NULL.

.SH RETURN VALUE
On success, this function returns a non-zero value and updates the program
header table entry at index
.IR ndx .
The program header table will be flagged with
.BR ELF_F_DIRTY .
On failure, it returns 0 and sets elf_errno.  If
.I elf
is NULL then 0 is returned without setting elf_errno.

.SH SEE ALSO
.BR elf_flagphdr (3),
.BR elf_getphdrnum (3),
.BR gelf_getphdr (3),
.BR gelf_newphdr (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_phdr ()
T}	Thread safety	MT-Safe
.TE

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