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// 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);
header.cpusubtype &= ~CPU_SUBTYPE_MASK;
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);
arch.cpusubtype &= ~CPU_SUBTYPE_MASK;
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