1 /* $NetBSD: elf_next.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 #if HAVE_NBTOOL_CONFIG_H
30 # include "nbtool_config.h"
31 #endif
32
33 #include <sys/cdefs.h>
34
35 #include <ar.h>
36 #include <assert.h>
37 #include <libelf.h>
38
39 #include "_libelf.h"
40
41 __RCSID("$NetBSD: elf_next.c,v 1.5 2024/03/03 17:37:33 christos Exp $");
42
43 Elf_Cmd
elf_next(Elf * e)44 elf_next(Elf *e)
45 {
46 off_t next;
47 Elf *parent;
48
49 if (e == NULL)
50 return (ELF_C_NULL);
51
52 if ((parent = e->e_parent) == NULL) {
53 LIBELF_SET_ERROR(ARGUMENT, 0);
54 return (ELF_C_NULL);
55 }
56
57 assert(parent->e_kind == ELF_K_AR);
58 assert(parent->e_cmd == ELF_C_READ);
59 assert(e->e_rawfile > parent->e_rawfile);
60
61 next = e->e_rawfile - parent->e_rawfile + (off_t) e->e_rawsize;
62 next = (next + 1) & ~1; /* round up to an even boundary */
63
64 /*
65 * Setup the 'e_next' field of the archive descriptor for the
66 * next call to 'elf_begin()'.
67 */
68 parent->e_u.e_ar.e_next = (next >= (off_t) parent->e_rawsize) ?
69 (off_t) 0 : next;
70
71 /*
72 * Return an error if the 'e_next' field falls outside the current
73 * file.
74 *
75 * This check is performed after updating the parent descriptor's
76 * 'e_next' field so that the next call to elf_begin(3) will terminate
77 * traversal of a too-small archive even if client code forgets to
78 * check the return value from elf_next(3).
79 */
80 if (next > (off_t) parent->e_rawsize) {
81 LIBELF_SET_ERROR(ARGUMENT, 0);
82 return (ELF_C_NULL);
83 }
84
85 return (ELF_C_READ);
86 }
87