.\" Copyright (c) 2006 Joseph Koshy.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" This software is provided by Joseph Koshy ``as is'' and
.\" any express or implied warranties, including, but not limited to, the
.\" implied warranties of merchantability and fitness for a particular purpose
.\" are disclaimed.  in no event shall Joseph Koshy be liable
.\" for any direct, indirect, incidental, special, exemplary, or consequential
.\" damages (including, but not limited to, procurement of substitute goods
.\" or services; loss of use, data, or profits; or business interruption)
.\" however caused and on any theory of liability, whether in contract, strict
.\" liability, or tort (including negligence or otherwise) arising in any way
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.\"
.\" $FreeBSD: release/10.0.0/lib/libelf/elf_rand.3 206622 2010-04-14 19:08:06Z uqs $
.\"
.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
