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 <assert.h>
30 #include <libelf.h>
31
32 #include "_libelf.h"
33
34 ELFTC_VCSID("$Id$");
35
36 /*
37 * Translate to/from the file representation of ELF objects.
38 *
39 * Translation could potentially involve the following
40 * transformations:
41 *
42 * - an endianness conversion,
43 * - a change of layout, as the file representation of ELF objects
44 * can differ from their in-memory representation.
45 * - a change in representation due to a layout version change.
46 */
47
48 Elf_Data *
_libelf_xlate(Elf_Data * dst,const Elf_Data * src,unsigned int encoding,int elfclass,int direction)49 _libelf_xlate(Elf_Data *dst, const Elf_Data *src, unsigned int encoding,
50 int elfclass, int direction)
51 {
52 int byteswap;
53 size_t cnt, dsz, fsz, msz;
54 uintptr_t sb, se, db, de;
55
56 if (encoding == ELFDATANONE)
57 encoding = LIBELF_PRIVATE(byteorder);
58
59 if ((encoding != ELFDATA2LSB && encoding != ELFDATA2MSB) ||
60 dst == NULL || src == NULL || dst == src) {
61 LIBELF_SET_ERROR(ARGUMENT, 0);
62 return (NULL);
63 }
64
65 assert(elfclass == ELFCLASS32 || elfclass == ELFCLASS64);
66 assert(direction == ELF_TOFILE || direction == ELF_TOMEMORY);
67
68 if (dst->d_version != src->d_version) {
69 LIBELF_SET_ERROR(UNIMPL, 0);
70 return (NULL);
71 }
72
73 if (src->d_buf == NULL || dst->d_buf == NULL) {
74 LIBELF_SET_ERROR(DATA, 0);
75 return (NULL);
76 }
77
78 if ((int) src->d_type < 0 || src->d_type >= ELF_T_NUM) {
79 LIBELF_SET_ERROR(DATA, 0);
80 return (NULL);
81 }
82
83 if ((fsz = (elfclass == ELFCLASS32 ? elf32_fsize : elf64_fsize)
84 (src->d_type, (size_t) 1, src->d_version)) == 0)
85 return (NULL);
86
87 msz = _libelf_msize(src->d_type, elfclass, src->d_version);
88
89 assert(msz > 0);
90
91 if (src->d_size % (direction == ELF_TOMEMORY ? fsz : msz)) {
92 LIBELF_SET_ERROR(DATA, 0);
93 return (NULL);
94 }
95
96 /*
97 * Determine the number of objects that need to be converted, and
98 * the space required for the converted objects in the destination
99 * buffer.
100 */
101 if (direction == ELF_TOMEMORY) {
102 cnt = (size_t) src->d_size / fsz;
103 dsz = cnt * msz;
104 } else {
105 cnt = (size_t) src->d_size / msz;
106 dsz = cnt * fsz;
107 }
108
109 if (dst->d_size < dsz) {
110 LIBELF_SET_ERROR(DATA, 0);
111 return (NULL);
112 }
113
114 sb = (uintptr_t) src->d_buf;
115 se = sb + (size_t) src->d_size;
116 db = (uintptr_t) dst->d_buf;
117 de = db + (size_t) dst->d_size;
118
119 /*
120 * Check for overlapping buffers. Note that db == sb is
121 * allowed.
122 */
123 if (db != sb && de > sb && se > db) {
124 LIBELF_SET_ERROR(DATA, 0);
125 return (NULL);
126 }
127
128 if ((direction == ELF_TOMEMORY ? db : sb) %
129 _libelf_malign(src->d_type, elfclass)) {
130 LIBELF_SET_ERROR(DATA, 0);
131 return (NULL);
132 }
133
134 dst->d_type = src->d_type;
135 dst->d_size = dsz;
136
137 byteswap = encoding != LIBELF_PRIVATE(byteorder);
138
139 if (src->d_size == 0 ||
140 (db == sb && !byteswap && fsz == msz))
141 return (dst); /* nothing more to do */
142
143 if (!(_libelf_get_translator(src->d_type, direction, elfclass))
144 (dst->d_buf, dsz, src->d_buf, cnt, byteswap)) {
145 LIBELF_SET_ERROR(DATA, 0);
146 return (NULL);
147 }
148
149 return (dst);
150 }
151