1/*-
2 * Copyright (c) 2006 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 <assert.h>
28
29#include "libelf.h"
30#include "_libelf.h"
31
32/*
33 * Translate to/from the file representation of ELF objects.
34 *
35 * Translation could potentially involve the following
36 * transformations:
37 *
38 * - an endianness conversion,
39 * - a change of layout, as the file representation of ELF objects
40 *   can differ from their in-memory representation.
41 * - a change in representation due to a layout version change.
42 */
43
44Elf_Data *
45_libelf_xlate(Elf_Data *dst, const Elf_Data *src, unsigned int encoding,
46    int elfclass, int direction)
47{
48        size_t cnt, dsz, fsz, msz;
49        uintptr_t sb, se, db, de;
50
51        if (encoding == ELFDATANONE)
52                encoding = LIBELF_PRIVATE(byteorder);
53
54        if ((encoding != ELFDATA2LSB && encoding != ELFDATA2MSB) ||
55            dst == NULL || src == NULL || dst == src)	{
56                LIBELF_SET_ERROR(ARGUMENT, 0);
57                return (NULL);
58        }
59
60        assert(elfclass == ELFCLASS32 || elfclass == ELFCLASS64);
61        assert(direction == ELF_TOFILE || direction == ELF_TOMEMORY);
62
63        if (dst->d_version != src->d_version) {
64                LIBELF_SET_ERROR(UNIMPL, 0);
65                return (NULL);
66        }
67
68        if  (src->d_buf == NULL || dst->d_buf == NULL ||
69            src->d_size == 0) {
70                LIBELF_SET_ERROR(DATA, 0);
71                return (NULL);
72        }
73
74        if ((int) src->d_type < 0 || src->d_type >= ELF_T_NUM) {
75                LIBELF_SET_ERROR(DATA, 0);
76                return (NULL);
77        }
78
79        if ((fsz = (elfclass == ELFCLASS32 ? elf32_fsize : elf64_fsize)(src->d_type,
80                 (size_t) 1, src->d_version)) == 0)
81                return (NULL);
82
83        msz = _libelf_msize(src->d_type, elfclass, src->d_version);
84
85        assert(msz > 0);
86
87        if (src->d_size % (direction == ELF_TOMEMORY ? fsz : msz)) {
88                LIBELF_SET_ERROR(DATA, 0);
89                return (NULL);
90        }
91
92        /*
93         * Determine the number of objects that need to be converted, and
94         * the space required for the converted objects in the destination
95         * buffer.
96         */
97        if (direction == ELF_TOMEMORY) {
98                cnt = src->d_size / fsz;
99                dsz = cnt * msz;
100        } else {
101                cnt = src->d_size / msz;
102                dsz = cnt * fsz;
103        }
104
105        if (dst->d_size  <  dsz) {
106                LIBELF_SET_ERROR(DATA, 0);
107                return (NULL);
108        }
109
110        sb = (uintptr_t) src->d_buf;
111        se = sb + src->d_size;
112        db = (uintptr_t) dst->d_buf;
113        de = db + dst->d_size;
114
115        /*
116         * Check for overlapping buffers.  Note that db == sb is
117         * allowed.
118         */
119        if (db != sb && de > sb && se > db) {
120                LIBELF_SET_ERROR(DATA, 0);
121                return (NULL);
122        }
123
124        if ((direction == ELF_TOMEMORY ? db : sb) %
125            _libelf_malign(src->d_type, elfclass)) {
126                LIBELF_SET_ERROR(DATA, 0);
127                return (NULL);
128        }
129
130        dst->d_type = src->d_type;
131        dst->d_size = dsz;
132
133        if (db == sb && encoding == LIBELF_PRIVATE(byteorder) &&
134            fsz == msz)
135                return (dst);	/* nothing more to do */
136
137        (_libelf_get_translator(src->d_type, direction, elfclass))(dst->d_buf,
138            src->d_buf, cnt, encoding != LIBELF_PRIVATE(byteorder));
139
140        return (dst);
141}
142