1.\"	$NetBSD: elf_rand.3,v 1.2 2014/03/09 16:58:04 christos Exp $
2.\"
3.\" Copyright (c) 2006,2008 Joseph Koshy.  All rights reserved.
4.\"
5.\" Redistribution and use in source and binary forms, with or without
6.\" modification, are permitted provided that the following conditions
7.\" are met:
8.\" 1. Redistributions of source code must retain the above copyright
9.\"    notice, this list of conditions and the following disclaimer.
10.\" 2. Redistributions in binary form must reproduce the above copyright
11.\"    notice, this list of conditions and the following disclaimer in the
12.\"    documentation and/or other materials provided with the distribution.
13.\"
14.\" This software is provided by Joseph Koshy ``as is'' and
15.\" any express or implied warranties, including, but not limited to, the
16.\" implied warranties of merchantability and fitness for a particular purpose
17.\" are disclaimed.  in no event shall Joseph Koshy be liable
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19.\" damages (including, but not limited to, procurement of substitute goods
20.\" or services; loss of use, data, or profits; or business interruption)
21.\" however caused and on any theory of liability, whether in contract, strict
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25.\"
26.\" Id: elf_rand.3 189 2008-07-20 10:38:08Z jkoshy
27.\"
28.Dd June 17, 2006
29.Os
30.Dt ELF_RAND 3
31.Sh NAME
32.Nm elf_rand
33.Nd provide sequential access to the next archive member
34.Sh LIBRARY
35.Lb libelf
36.Sh SYNOPSIS
37.In libelf.h
38.Ft off_t
39.Fn elf_rand "Elf *archive" "off_t offset"
40.Sh DESCRIPTION
41The
42.Fn elf_rand
43function causes the ELF descriptor
44.Ar archive
45to be adjusted so that the next call to
46.Xr elf_begin 3
47will provide access to the archive member at byte offset
48.Ar offset
49in the archive.
50Argument
51.Ar offset
52is the byte offset from the start of the archive to the beginning of
53the archive header for the desired member.
54.Pp
55Archive member offsets may be retrieved using the
56.Xr elf_getarsym 3
57function.
58.Sh RETURN VALUES
59Function
60.Fn elf_rand
61returns
62.Ar offset
63if successful or zero in case of an error.
64.Sh EXAMPLES
65To process all the members of an archive use:
66.Bd -literal -offset indent
67off_t off;
68Elf *archive, *e;
69\&...
70cmd = ELF_C_READ;
71archive = elf_begin(fd, cmd, NULL);
72while ((e = elf_begin(fd, cmd, archive)) != (Elf *) 0)
73{
74	... process `e' here ...
75	elf_end(e);
76
77	off = ...new value...;
78	if (elf_rand(archive, off) != off) {
79		... process error ...
80	}
81}
82elf_end(archive);
83.Ed
84.Pp
85To rewind an archive, use:
86.Bd -literal -offset indent
87Elf *archive;
88\&...
89if (elf_rand(archive, SARMAG) != SARMAG) {
90	... error ...
91}
92.Ed
93.Sh ERRORS
94Function
95.Fn elf_rand
96may fail with the following errors:
97.Bl -tag -width "[ELF_E_RESOURCE]"
98.It Bq Er ELF_E_ARGUMENT
99Argument
100.Ar archive
101was null.
102.It Bq Er ELF_E_ARGUMENT
103Argument
104.Ar archive
105was not a descriptor for an
106.Xr ar 1
107archive.
108.It Bq Er ELF_E_ARCHIVE
109Argument
110.Ar offset
111did not correspond to the start of an archive member header.
112.El
113.Sh SEE ALSO
114.Xr ar 1 ,
115.Xr elf 3 ,
116.Xr elf_begin 3 ,
117.Xr elf_end 3 ,
118.Xr elf_getarsym 3 ,
119.Xr elf_next 3 ,
120.Xr gelf 3
121