1 /* $NetBSD: elf_rand.c,v 1.5 2024/03/03 17:37:33 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2006,2008 Joseph Koshy 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 31 #include <ar.h> 32 #include <libelf.h> 33 34 #include "_libelf.h" 35 36 __RCSID("$NetBSD: elf_rand.c,v 1.5 2024/03/03 17:37:33 christos Exp $"); 37 38 off_t 39 elf_rand(Elf *ar, off_t offset) 40 { 41 struct ar_hdr *arh; 42 off_t offset_of_member; 43 44 if (ar == NULL || ar->e_kind != ELF_K_AR || 45 (offset & 1) || offset < SARMAG || 46 offset >= ar->e_rawsize) { 47 LIBELF_SET_ERROR(ARGUMENT, 0); 48 return 0; 49 } 50 51 offset_of_member = offset + (off_t) sizeof(struct ar_hdr); 52 53 if (offset_of_member <= 0 || /* Numeric overflow. */ 54 offset_of_member >= ar->e_rawsize) { 55 LIBELF_SET_ERROR(ARGUMENT, 0); 56 return 0; 57 } 58 59 arh = (struct ar_hdr *) (ar->e_rawfile + offset); 60 61 /* a too simple sanity check */ 62 if (arh->ar_fmag[0] != '`' || arh->ar_fmag[1] != '\n') { 63 LIBELF_SET_ERROR(ARCHIVE, 0); 64 return 0; 65 } 66 67 ar->e_u.e_ar.e_next = offset; 68 69 return (offset); 70 } 71