/*      $NetBSD: elf_rand.c,v 1.5 2024/03/03 17:37:33 christos Exp $    */

/*-
* Copyright (c) 2006,2008 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 THE AUTHOR AND CONTRIBUTORS ``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 THE AUTHOR OR CONTRIBUTORS 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
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include <sys/cdefs.h>

#include <ar.h>
#include <libelf.h>

#include "_libelf.h"

__RCSID("$NetBSD: elf_rand.c,v 1.5 2024/03/03 17:37:33 christos Exp $");

off_t
elf_rand(Elf *ar, off_t offset)
{
       struct ar_hdr *arh;
       off_t offset_of_member;

       if (ar == NULL || ar->e_kind != ELF_K_AR ||
           (offset & 1) || offset < SARMAG ||
           offset >= ar->e_rawsize) {
               LIBELF_SET_ERROR(ARGUMENT, 0);
               return 0;
       }

       offset_of_member = offset + (off_t) sizeof(struct ar_hdr);

       if (offset_of_member <= 0 || /* Numeric overflow. */
           offset_of_member >= ar->e_rawsize) {
               LIBELF_SET_ERROR(ARGUMENT, 0);
               return 0;
       }

       arh = (struct ar_hdr *) (ar->e_rawfile + offset);

       /* a too simple sanity check */
       if (arh->ar_fmag[0] != '`' || arh->ar_fmag[1] != '\n') {
               LIBELF_SET_ERROR(ARCHIVE, 0);
               return 0;
       }

       ar->e_u.e_ar.e_next = offset;

       return (offset);
}