lib/libelf/elf_rand.c

   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 LIBELF_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             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 }