1  /*-
 2   * Copyright (c) 2006,2008 Joseph Koshy
 3   * 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 THE AUTHOR AND CONTRIBUTORS ``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 THE AUTHOR OR CONTRIBUTORS BE LIABLE
18   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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
22   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24   * SUCH DAMAGE.
25   */
26  
27  #include <sys/cdefs.h>
28  
29  #include <ar.h>
30  #include <libelf.h>
31  
32  #include "_libelf.h"
33  
34  ELFTC_VCSID("$Id$");
35  
36  off_t
37  elf_rand(Elf *ar, off_t offset)
38  {
39  	struct ar_hdr *arh;
40  
41  	if (ar == NULL || ar->e_kind != ELF_K_AR ||
42  	    (offset & 1) || offset < SARMAG ||
43  	    (size_t) offset + sizeof(struct ar_hdr) >= ar->e_rawsize) {
44  		LIBELF_SET_ERROR(ARGUMENT, 0);
45  		return 0;
46  	}
47  
48  	arh = (struct ar_hdr *) (ar->e_rawfile + offset);
49  
50  	/* a too simple sanity check */
51  	if (arh->ar_fmag[0] != '`' || arh->ar_fmag[1] != '\n') {
52  		LIBELF_SET_ERROR(ARCHIVE, 0);
53  		return 0;
54  	}
55  
56  	ar->e_u.e_ar.e_next = offset;
57  
58  	return (offset);
59  }