diff options
Diffstat (limited to 'src/common/mac/macho_walker.cc')
| -rw-r--r-- | src/common/mac/macho_walker.cc | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/src/common/mac/macho_walker.cc b/src/common/mac/macho_walker.cc new file mode 100644 index 00000000..96dca406 --- /dev/null +++ b/src/common/mac/macho_walker.cc @@ -0,0 +1,207 @@ +// 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/loader.h> +#include <mach-o/swap.h> +#include <unistd.h> + +#include "common/mac/macho_walker.h" + +namespace MacFileUtilities { + +MachoWalker::MachoWalker(const char *path, LoadCommandCallback callback, + void *context) + : callback_(callback), + callback_context_(context) { + file_ = open(path, O_RDONLY); +} + +MachoWalker::~MachoWalker() { + if (file_ != -1) + close(file_); +} + +int MachoWalker::ValidateCPUType(int cpu_type) { + // If the user didn't specify, try to use the local architecture. If that + // fails, use the base type for the executable. + if (cpu_type == 0) { + const NXArchInfo *arch = NXGetLocalArchInfo(); + if (arch) + cpu_type = arch->cputype; + else +#if __ppc__ + cpu_type = CPU_TYPE_POWERPC; +#elif __i386__ + cpu_type = CPU_TYPE_X86; +#else +#error Unknown architecture -- are you on a PDP-11? +#endif + } + + return cpu_type; +} + +bool MachoWalker::WalkHeader(int cpu_type) { + int valid_cpu_type = ValidateCPUType(cpu_type); + off_t offset; + if (FindHeader(valid_cpu_type, 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) { + return pread(file_, buffer, size, offset) == (ssize_t)size; +} + +bool MachoWalker::FindHeader(int cpu_type, off_t &offset) { + int valid_cpu_type = ValidateCPUType(cpu_type); + // 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; + 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 + cpu_type_t header_cpu_type; + if (!ReadBytes(&header_cpu_type, sizeof(header_cpu_type), offset)) + return false; + + if (NXHostByteOrder() != NX_BigEndian) + header_cpu_type = NXSwapLong(header_cpu_type); + + if (valid_cpu_type != header_cpu_type) + 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) + swap_fat_header(&fat, NXHostByteOrder()); + + 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) + swap_fat_arch(&arch, 1, NXHostByteOrder()); + + if (arch.cputype == valid_cpu_type) { + 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) + swap_mach_header(&header, NXHostByteOrder()); + + return WalkHeaderCore(offset + sizeof(header), header.ncmds, swap); +} + +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) + swap_mach_header_64(&header, NXHostByteOrder()); + + return WalkHeaderCore(offset + sizeof(header), header.ncmds, swap); +} + +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) + swap_load_command(&cmd, NXHostByteOrder()); + + // Call the user callback + if (callback_ && !callback_(this, &cmd, offset, swap, callback_context_)) + break; + + offset += cmd.cmdsize; + } + + return true; +} + +} // namespace MacFileUtilities |