xref: /freebsd/contrib/elftoolchain/libelf/elf_rand.3 (revision ae500c1ff8974130f7f2692772cf288b90349e0d)

.\" Copyright (c) 2006,2008 Joseph Koshy.  All rights reserved.
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.\" $Id: elf_rand.3 3639 2018-10-14 14:07:02Z jkoshy $
.\"
.Dd June 17, 2006
.Dt ELF_RAND 3
.Os
.Sh NAME
.Nm elf_rand
.Nd provide sequential access to the next archive member
.Sh LIBRARY
.Lb libelf
.Sh SYNOPSIS
.In libelf.h
.Ft off_t
.Fn elf_rand "Elf *archive" "off_t offset"
.Sh DESCRIPTION
The
.Fn elf_rand
function causes the ELF descriptor
.Ar archive
to be adjusted so that the next call to
.Xr elf_begin 3
will provide access to the archive member at byte offset
.Ar offset
in the archive.
Argument
.Ar offset
is the byte offset from the start of the archive to the beginning of
the archive header for the desired member.
.Pp
Archive member offsets may be retrieved using the
.Xr elf_getarsym 3
function.
.Sh RETURN VALUES
Function
.Fn elf_rand
returns
.Ar offset
if successful or zero in case of an error.
.Sh EXAMPLES
To process all the members of an archive use:
.Bd -literal -offset indent
off_t off;
Elf *archive, *e;
\&...
cmd = ELF_C_READ;
archive = elf_begin(fd, cmd, NULL);
while ((e = elf_begin(fd, cmd, archive)) != (Elf *) 0)
{
	... process `e' here ...
	elf_end(e);

	off = ...new value...;
	if (elf_rand(archive, off) != off) {
		... process error ...
	}
}
elf_end(archive);
.Ed
.Pp
To rewind an archive, use:
.Bd -literal -offset indent
Elf *archive;
\&...
if (elf_rand(archive, SARMAG) != SARMAG) {
	... error ...
}
.Ed
.Sh ERRORS
Function
.Fn elf_rand
may fail with the following errors:
.Bl -tag -width "[ELF_E_RESOURCE]"
.It Bq Er ELF_E_ARGUMENT
Argument
.Ar archive
was null.
.It Bq Er ELF_E_ARGUMENT
Argument
.Ar archive
was not a descriptor for an
.Xr ar 1
archive.
.It Bq Er ELF_E_ARCHIVE
Argument
.Ar offset
did not correspond to the start of an archive member header.
.El
.Sh SEE ALSO
.Xr ar 1 ,
.Xr elf 3 ,
.Xr elf_begin 3 ,
.Xr elf_end 3 ,
.Xr elf_getarsym 3 ,
.Xr elf_next 3 ,
.Xr gelf 3