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 <ar.h> 28 #include <assert.h> 29 #include <libelf.h> 30 31 #include "_libelf.h" 32 33 ELFTC_VCSID("$Id: elf_next.c 3710 2019-03-12 09:42:35Z jkoshy $"); 34 35 Elf_Cmd 36 elf_next(Elf *e) 37 { 38 off_t next; 39 Elf *parent; 40 41 if (e == NULL) 42 return (ELF_C_NULL); 43 44 if ((parent = e->e_parent) == NULL) { 45 LIBELF_SET_ERROR(ARGUMENT, 0); 46 return (ELF_C_NULL); 47 } 48 49 assert(parent->e_kind == ELF_K_AR); 50 assert(parent->e_cmd == ELF_C_READ); 51 assert(e->e_rawfile > parent->e_rawfile); 52 53 next = e->e_rawfile - parent->e_rawfile + (off_t) e->e_rawsize; 54 next = (next + 1) & ~1; /* round up to an even boundary */ 55 56 /* 57 * Setup the 'e_next' field of the archive descriptor for the 58 * next call to 'elf_begin()'. 59 */ 60 parent->e_u.e_ar.e_next = (next >= (off_t) parent->e_rawsize) ? 61 (off_t) 0 : next; 62 63 /* 64 * Return an error if the 'e_next' field falls outside the current 65 * file. 66 * 67 * This check is performed after updating the parent descriptor's 68 * 'e_next' field so that the next call to elf_begin(3) will terminate 69 * traversal of a too-small archive even if client code forgets to 70 * check the return value from elf_next(3). 71 */ 72 if (next > (off_t) parent->e_rawsize) { 73 LIBELF_SET_ERROR(ARGUMENT, 0); 74 return (ELF_C_NULL); 75 } 76 77 return (ELF_C_READ); 78 } 79