summaryrefslogtreecommitdiffstats
blob: 1acd86656b6c91592a3938a75a2569e1edca8f01 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
// Copyright (c) 2006, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// macho_walker.cc: Iterate over the load commands in a mach-o file
//
// See macho_walker.h for documentation
//
// Author: Dan Waylonis

#include <assert.h>
#include <fcntl.h>
#include <mach-o/arch.h>
#include <mach-o/fat.h>
#include <mach-o/loader.h>
#include <string.h>
#include <unistd.h>

#include "common/mac/byteswap.h"
#include "common/mac/macho_walker.h"
#include "common/mac/macho_utilities.h"

namespace MacFileUtilities {

MachoWalker::MachoWalker(const char *path, LoadCommandCallback callback,
                         void *context)
    : file_(-1),
      memory_(NULL),
      memory_size_(0),
      callback_(callback),
      callback_context_(context),
      current_header_(NULL),
      current_header_size_(0),
      current_header_offset_(0) {
  file_ = open(path, O_RDONLY);
}

MachoWalker::MachoWalker(void *memory, size_t size,
                         LoadCommandCallback callback, void *context)
    : file_(-1),
      memory_(memory),
      memory_size_(size),
      callback_(callback),
      callback_context_(context),
      current_header_(NULL),
      current_header_size_(0),
      current_header_offset_(0) {
}

MachoWalker::~MachoWalker() {
  if (file_ != -1)
    close(file_);
}

bool MachoWalker::WalkHeader(cpu_type_t cpu_type, cpu_subtype_t cpu_subtype) {
  cpu_type_t valid_cpu_type = cpu_type;
  cpu_subtype_t valid_cpu_subtype = cpu_subtype;
  // if |cpu_type| is 0, use the native cpu type.
  if (cpu_type == 0) {
    const NXArchInfo *arch = NXGetLocalArchInfo();
    assert(arch);
    valid_cpu_type = arch->cputype;
    valid_cpu_subtype = CPU_SUBTYPE_MULTIPLE;
  }
  off_t offset;
  if (FindHeader(valid_cpu_type, valid_cpu_subtype, offset)) {
    if (cpu_type & CPU_ARCH_ABI64)
      return WalkHeader64AtOffset(offset);

    return WalkHeaderAtOffset(offset);
  }

  return false;
}

bool MachoWalker::ReadBytes(void *buffer, size_t size, off_t offset) {
  if (memory_) {
    if (offset < 0)
      return false;
    bool result = true;
    if (offset + size > memory_size_) {
      if (static_cast<size_t>(offset) >= memory_size_)
        return false;
      size = memory_size_ - static_cast<size_t>(offset);
      result = false;
    }
    memcpy(buffer, static_cast<char *>(memory_) + offset, size);
    return result;
  } else {
    return pread(file_, buffer, size, offset) == (ssize_t)size;
  }
}

bool MachoWalker::CurrentHeader(struct mach_header_64 *header, off_t *offset) {
  if (current_header_) {
    memcpy(header, current_header_, sizeof(mach_header_64));
    *offset = current_header_offset_;
    return true;
  }

  return false;
}

bool MachoWalker::FindHeader(cpu_type_t cpu_type,
                             cpu_subtype_t cpu_subtype,
                             off_t &offset) {
  // Read the magic bytes that's common amongst all mach-o files
  uint32_t magic;
  if (!ReadBytes(&magic, sizeof(magic), 0))
    return false;

  offset = sizeof(magic);

  // Figure out what type of file we've got
  bool is_fat = false;
  if (magic == FAT_MAGIC || magic == FAT_CIGAM) {
    is_fat = true;
  }
  else if (magic != MH_MAGIC && magic != MH_CIGAM && magic != MH_MAGIC_64 &&
           magic != MH_CIGAM_64) {
    return false;
  }

  if (!is_fat) {
    // If we don't have a fat header, check if the cpu type matches the single
    // header
    struct mach_header header;
    if (!ReadBytes(&header, sizeof(header), 0))
      return false;

    if (magic == MH_CIGAM || magic == MH_CIGAM_64)
      breakpad_swap_mach_header(&header);

    if (cpu_type != header.cputype ||
        (cpu_subtype != CPU_SUBTYPE_MULTIPLE &&
         cpu_subtype != header.cpusubtype)) {
      return false;
    }

    offset = 0;
    return true;
  } else {
    // Read the fat header and find an appropriate architecture
    offset = 0;
    struct fat_header fat;
    if (!ReadBytes(&fat, sizeof(fat), offset))
      return false;

    if (NXHostByteOrder() != NX_BigEndian)
      breakpad_swap_fat_header(&fat);

    offset += sizeof(fat);

    // Search each architecture for the desired one
    struct fat_arch arch;
    for (uint32_t i = 0; i < fat.nfat_arch; ++i) {
      if (!ReadBytes(&arch, sizeof(arch), offset))
        return false;

      if (NXHostByteOrder() != NX_BigEndian)
        breakpad_swap_fat_arch(&arch, 1);

      if (arch.cputype == cpu_type &&
          (cpu_subtype == CPU_SUBTYPE_MULTIPLE ||
           arch.cpusubtype == cpu_subtype)) {
        offset = arch.offset;
        return true;
      }

      offset += sizeof(arch);
    }
  }

  return false;
}

bool MachoWalker::WalkHeaderAtOffset(off_t offset) {
  struct mach_header header;
  if (!ReadBytes(&header, sizeof(header), offset))
    return false;

  bool swap = (header.magic == MH_CIGAM);
  if (swap)
    breakpad_swap_mach_header(&header);

  // Copy the data into the mach_header_64 structure.  Since the 32-bit and
  // 64-bit only differ in the last field (reserved), this is safe to do.
  struct mach_header_64 header64;
  memcpy((void *)&header64, (const void *)&header, sizeof(header));
  header64.reserved = 0;

  current_header_ = &header64;
  current_header_size_ = sizeof(header); // 32-bit, not 64-bit
  current_header_offset_ = offset;
  offset += current_header_size_;
  bool result = WalkHeaderCore(offset, header.ncmds, swap);
  current_header_ = NULL;
  current_header_size_ = 0;
  current_header_offset_ = 0;
  return result;
}

bool MachoWalker::WalkHeader64AtOffset(off_t offset) {
  struct mach_header_64 header;
  if (!ReadBytes(&header, sizeof(header), offset))
    return false;

  bool swap = (header.magic == MH_CIGAM_64);
  if (swap)
    breakpad_swap_mach_header_64(&header);

  current_header_ = &header;
  current_header_size_ = sizeof(header);
  current_header_offset_ = offset;
  offset += current_header_size_;
  bool result = WalkHeaderCore(offset, header.ncmds, swap);
  current_header_ = NULL;
  current_header_size_ = 0;
  current_header_offset_ = 0;
  return result;
}

bool MachoWalker::WalkHeaderCore(off_t offset, uint32_t number_of_commands,
                                 bool swap) {
  for (uint32_t i = 0; i < number_of_commands; ++i) {
    struct load_command cmd;
    if (!ReadBytes(&cmd, sizeof(cmd), offset))
      return false;

    if (swap)
      breakpad_swap_load_command(&cmd);

    // Call the user callback
    if (callback_ && !callback_(this, &cmd, offset, swap, callback_context_))
      break;

    offset += cmd.cmdsize;
  }

  return true;
}

}  // namespace MacFileUtilities