1.\" Copyright (c) 2006,2008 Joseph Koshy.  All rights reserved.
2.\"
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4.\" modification, are permitted provided that the following conditions
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6.\" 1. Redistributions of source code must retain the above copyright
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12.\" This software is provided by Joseph Koshy ``as is'' and
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24.\" $Id$
25.\"
26.Dd June 17, 2006
27.Os
28.Dt ELF_RAND 3
29.Sh NAME
30.Nm elf_rand
31.Nd provide sequential access to the next archive member
32.Sh LIBRARY
33.Lb libelf
34.Sh SYNOPSIS
35.In libelf.h
36.Ft off_t
37.Fn elf_rand "Elf *archive" "off_t offset"
38.Sh DESCRIPTION
39The
40.Fn elf_rand
41function causes the ELF descriptor
42.Ar archive
43to be adjusted so that the next call to
44.Xr elf_begin 3
45will provide access to the archive member at byte offset
46.Ar offset
47in the archive.
48Argument
49.Ar offset
50is the byte offset from the start of the archive to the beginning of
51the archive header for the desired member.
52.Pp
53Archive member offsets may be retrieved using the
54.Xr elf_getarsym 3
55function.
56.Sh RETURN VALUES
57Function
58.Fn elf_rand
59returns
60.Ar offset
61if successful or zero in case of an error.
62.Sh EXAMPLES
63To process all the members of an archive use:
64.Bd -literal -offset indent
65off_t off;
66Elf *archive, *e;
67\&...
68cmd = ELF_C_READ;
69archive = elf_begin(fd, cmd, NULL);
70while ((e = elf_begin(fd, cmd, archive)) != (Elf *) 0)
71{
72	... process `e' here ...
73	elf_end(e);
74
75	off = ...new value...;
76	if (elf_rand(archive, off) != off) {
77		... process error ...
78	}
79}
80elf_end(archive);
81.Ed
82.Pp
83To rewind an archive, use:
84.Bd -literal -offset indent
85Elf *archive;
86\&...
87if (elf_rand(archive, SARMAG) != SARMAG) {
88	... error ...
89}
90.Ed
91.Sh ERRORS
92Function
93.Fn elf_rand
94may fail with the following errors:
95.Bl -tag -width "[ELF_E_RESOURCE]"
96.It Bq Er ELF_E_ARGUMENT
97Argument
98.Ar archive
99was null.
100.It Bq Er ELF_E_ARGUMENT
101Argument
102.Ar archive
103was not a descriptor for an
104.Xr ar 1
105archive.
106.It Bq Er ELF_E_ARCHIVE
107Argument
108.Ar offset
109did not correspond to the start of an archive member header.
110.El
111.Sh SEE ALSO
112.Xr ar 1 ,
113.Xr elf 3 ,
114.Xr elf_begin 3 ,
115.Xr elf_end 3 ,
116.Xr elf_getarsym 3 ,
117.Xr elf_next 3 ,
118.Xr gelf 3
119