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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

 extern "C" {  // necessary for Leopard

   #include <assert.h>

   #include <fcntl.h>

   #include <mach-o/arch.h>

   #include <mach-o/loader.h>

   #include <mach-o/swap.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_(0),

       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_(0),

       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)

       swap_mach_header(&header, NXHostByteOrder());

     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)

       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 == 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)

     swap_mach_header(&header, NXHostByteOrder());

   // 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, NXHostByteOrder());

   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)

       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