Add classes to: walk mach-o files, look for identifiers, and return a 16 byte unique identifier. Fixes #106.

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@102 4c0a9323-5329-0410-9bdc-e9ce6186880e

6 files changed, 919 insertions, 0 deletions

diff --git a/src/common/mac/file_id.cc b/src/common/mac/file_id.cc
new file mode 100644
index 00000000..f74f861e
--- /dev/null
+++ b/src/common/mac/file_id.cc
@@ -0,0 +1,104 @@
+// 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.
+//
+// file_id.cc: Return a unique identifier for a file
+//
+// See file_id.h for documentation
+//
+// Author: Dan Waylonis
+
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "common/mac/file_id.h"
+#include "common/mac/macho_id.h"
+
+using MacFileUtilities::MachoID;
+
+namespace google_airbag {
+
+FileID::FileID(const char *path) {
+  strlcpy(path_, path, sizeof(path_));
+}
+
+bool FileID::FileIdentifier(unsigned char identifier[16]) {
+  int fd = open(path_, O_RDONLY);
+  if (fd == -1)
+    return false;
+
+  MD5_CTX md5;
+  MD5_Init(&md5);
+
+  // Read 4k x 2 bytes at a time.  This is faster than just 4k bytes, but
+  // doesn't seem to be an unreasonable size for the stack.
+  unsigned char buffer[4096 * 2];
+  size_t buffer_size = sizeof(buffer);
+  while ((buffer_size = read(fd, buffer, buffer_size) > 0)) {
+    MD5_Update(&md5, buffer, buffer_size);
+  }
+
+  close(fd);
+  MD5_Final(identifier, &md5);
+
+  return true;
+}
+
+bool FileID::MachoIdentifier(int cpu_type, unsigned char identifier[16]) {
+  MachoID macho(path_);
+
+  if (macho.UUIDCommand(cpu_type, identifier))
+    return true;
+
+  if (macho.IDCommand(cpu_type, identifier))
+    return true;
+
+  return macho.MD5(cpu_type, identifier);
+}
+
+// static
+void FileID::ConvertIdentifierToString(const unsigned char identifier[16],
+                                       char *buffer, int buffer_length) {
+  int buffer_idx = 0;
+  for (int idx = 0; (buffer_idx < buffer_length) && (idx < 16); ++idx) {
+    int hi = (identifier[idx] >> 4) & 0x0F;
+    int lo = (identifier[idx]) & 0x0F;
+
+    if (idx == 4 || idx == 6 || idx == 8 || idx == 10)
+      buffer[buffer_idx++] = '-';
+
+    buffer[buffer_idx++] = (hi >= 10) ? 'A' + hi - 10 : '0' + hi;
+    buffer[buffer_idx++] = (lo >= 10) ? 'A' + lo - 10 : '0' + lo;
+  }
+
+  // NULL terminate
+  buffer[(buffer_idx < buffer_length) ? buffer_idx : buffer_idx - 1] = 0;
+}
+
+}  // namespace google_airbag
diff --git a/src/common/mac/file_id.h b/src/common/mac/file_id.h
new file mode 100644
index 00000000..663aa369
--- /dev/null
+++ b/src/common/mac/file_id.h
@@ -0,0 +1,78 @@
+// 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.
+//
+// file_id.h: Return a unique identifier for a file
+//
+// Author: Dan Waylonis
+
+#ifndef COMMON_MAC_FILE_ID_H__
+#define COMMON_MAC_FILE_ID_H__
+
+#include <limits.h>
+
+namespace google_airbag {
+
+class FileID {
+ public:
+  FileID(const char *path);
+  ~FileID() {};
+
+  // Load the identifier for the file path specified in the constructor into
+  // |identifier|.  Return false if the identifier could not be created for the
+  // file.
+  // The current implementation will return the MD5 hash of the file's bytes.
+  bool FileIdentifier(unsigned char identifier[16]);
+
+  // Treat the file as a mach-o file that will contain one or more archicture.
+  // Accepted values for |cpu_type| (e.g., CPU_TYPE_X86 or CPU_TYPE_POWERPC)
+  // are listed in /usr/include/mach/machine.h.
+  // If |cpu_type| is 0, then the native cpu type is used.
+  // Returns false if opening the file failed or if the |cpu_type| is not
+  // present in the file.
+  // Return the unique identifier in |identifier|.
+  // The current implementation will look for the (in order of priority):
+  // LC_UUID, LC_ID_DYLIB, or MD5 hash of the given |cpu_type|.
+  bool MachoIdentifier(int cpu_type, unsigned char identifier[16]);
+
+  // Convert the |identifier| data to a NULL terminated string.  The string will
+  // be formatted as a UUID (e.g., 22F065BB-FC9C-49F7-80FE-26A7CEBD7BCE).
+  // The |buffer| should be at least 37 bytes long to receive all of the data
+  // and termination.  Shorter buffers will contain truncated data.
+  static void ConvertIdentifierToString(const unsigned char identifier[16],
+                                        char *buffer, int buffer_length);
+
+ private:
+  // Storage for the path specified
+  char path_[PATH_MAX];
+};
+
+}  // namespace google_airbag
+
+#endif  // COMMON_MAC_FILE_ID_H__
+
diff --git a/src/common/mac/macho_id.cc b/src/common/mac/macho_id.cc
new file mode 100644
index 00000000..f152d275
--- /dev/null
+++ b/src/common/mac/macho_id.cc
@@ -0,0 +1,312 @@
+// 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_id.cc: Functions to gather identifying information from a macho file
+//
+// See macho_id.h for documentation
+//
+// Author: Dan Waylonis
+
+#include <fcntl.h>
+#include <mach-o/loader.h>
+#include <mach-o/swap.h>
+#include <openssl/md5.h>
+#include <openssl/sha.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "common/mac/macho_id.h"
+#include "common/mac/macho_walker.h"
+
+namespace MacFileUtilities {
+
+MachoID::MachoID(const char *path) {
+  strlcpy(path_, path, sizeof(path_));
+  file_ = open(path, O_RDONLY);
+}
+
+MachoID::~MachoID() {
+  if (file_ != -1)
+    close(file_);
+}
+
+// The CRC info is from http://en.wikipedia.org/wiki/Adler-32
+// With optimizations from http://www.zlib.net/
+
+// The largest prime smaller than 65536
+#define MOD_ADLER 65521
+// MAX_BLOCK is the largest n such that 255n(n+1)/2 + (n+1)(MAX_BLOCK-1) <= 2^32-1
+#define MAX_BLOCK 5552
+
+void MachoID::UpdateCRC(unsigned char *bytes, size_t size) {
+// Unrolled loops for summing
+#define DO1(buf,i)  {sum1 += (buf)[i]; sum2 += sum1;}
+#define DO2(buf,i)  DO1(buf,i); DO1(buf,i+1);
+#define DO4(buf,i)  DO2(buf,i); DO2(buf,i+2);
+#define DO8(buf,i)  DO4(buf,i); DO4(buf,i+4);
+#define DO16(buf)   DO8(buf,0); DO8(buf,8);
+  // Split up the crc
+  uint32_t sum1 = crc_ & 0xFFFF;
+  uint32_t sum2 = (crc_ >> 16) & 0xFFFF;
+
+  // Do large blocks
+  while (size >= MAX_BLOCK) {
+    size -= MAX_BLOCK;
+    int block_count = MAX_BLOCK / 16;
+    do {
+      DO16(bytes);
+      bytes += 16;
+    } while (--block_count);
+    sum1 %= MOD_ADLER;
+    sum2 %= MOD_ADLER;
+  }
+
+  // Do remaining bytes
+  if (size) {
+    while (size >= 16) {
+      size -= 16;
+      DO16(bytes);
+      bytes += 16;
+    }
+    while (size--) {
+      sum1 += *bytes++;
+      sum2 += sum1;
+    }
+    sum1 %= MOD_ADLER;
+    sum2 %= MOD_ADLER;
+    crc_ = (sum2 << 16) | sum1;
+  }
+}
+
+void MachoID::UpdateMD5(unsigned char *bytes, size_t size) {
+  MD5_Update(&md5_context_, bytes, size);
+}
+
+void MachoID::UpdateSHA1(unsigned char *bytes, size_t size) {
+  SHA_Update(&sha1_context_, bytes, size);
+}
+
+void MachoID::Update(unsigned char *bytes, size_t size) {
+  if (update_function_)
+    (this->*update_function_)(bytes, size);
+}
+
+bool MachoID::UUIDCommand(int cpu_type, unsigned char bytes[16]) {
+  struct uuid_command uuid_cmd;
+  MachoWalker walker(path_, UUIDWalkerCB, &uuid_cmd);
+
+  uuid_cmd.cmd = 0;
+  if (!walker.WalkHeader(cpu_type))
+    return false;
+
+  // If we found the command, we'll have initialized the uuid_command
+  // structure
+  if (uuid_cmd.cmd == LC_UUID) {
+    memcpy(bytes, uuid_cmd.uuid, sizeof(uuid_cmd.uuid));
+    return true;
+  }
+
+  return false;
+}
+
+bool MachoID::IDCommand(int cpu_type, unsigned char identifier[16]) {
+  struct dylib_command dylib_cmd;
+  MachoWalker walker(path_, IDWalkerCB, &dylib_cmd);
+
+  dylib_cmd.cmd = 0;
+  if (!walker.WalkHeader(cpu_type))
+    return false;
+
+  // If we found the command, we'll have initialized the dylib_command
+  // structure
+  if (dylib_cmd.cmd == LC_ID_DYLIB) {
+    // Take the timestamp, version, and compatability version bytes to form
+    // the first 12 bytes, pad the rest with zeros
+    identifier[0] = (dylib_cmd.dylib.timestamp >> 24) & 0xFF;
+    identifier[1] = (dylib_cmd.dylib.timestamp >> 16) & 0xFF;
+    identifier[2] = (dylib_cmd.dylib.timestamp >> 8) & 0xFF;
+    identifier[3] = dylib_cmd.dylib.timestamp & 0xFF;
+    identifier[4] = (dylib_cmd.dylib.current_version >> 24) & 0xFF;
+    identifier[5] = (dylib_cmd.dylib.current_version >> 16) & 0xFF;
+    identifier[6] = (dylib_cmd.dylib.current_version >> 8) & 0xFF;
+    identifier[7] = dylib_cmd.dylib.current_version & 0xFF;
+    identifier[8] = (dylib_cmd.dylib.compatibility_version >> 24) & 0xFF;
+    identifier[9] = (dylib_cmd.dylib.compatibility_version >> 16) & 0xFF;
+    identifier[10] = (dylib_cmd.dylib.compatibility_version >> 8) & 0xFF;
+    identifier[11] = dylib_cmd.dylib.compatibility_version & 0xFF;
+    identifier[12] = identifier[13] = identifier[14] = identifier[15] = 0;
+
+    return true;
+  }
+
+  return false;
+}
+
+uint32_t MachoID::Adler32(int cpu_type) {
+  MachoWalker walker(path_, WalkerCB, this);
+  update_function_ = &MachoID::UpdateCRC;
+  crc_ = 0;
+
+  if (!walker.WalkHeader(cpu_type))
+    return 0;
+
+  return crc_;
+}
+
+bool MachoID::MD5(int cpu_type, unsigned char identifier[16]) {
+  MachoWalker walker(path_, WalkerCB, this);
+  update_function_ = &MachoID::UpdateMD5;
+
+  if (MD5_Init(&md5_context_)) {
+    if (!walker.WalkHeader(cpu_type))
+      return false;
+
+    MD5_Final(identifier, &md5_context_);
+    return true;
+  }
+
+  return false;
+}
+
+bool MachoID::SHA1(int cpu_type, unsigned char identifier[16]) {
+  MachoWalker walker(path_, WalkerCB, this);
+  update_function_ = &MachoID::UpdateSHA1;
+
+  if (SHA_Init(&sha1_context_)) {
+    if (!walker.WalkHeader(cpu_type))
+      return false;
+
+    SHA_Final(identifier, &sha1_context_);
+    return true;
+  }
+
+  return false;
+}
+
+// static
+bool MachoID::WalkerCB(MachoWalker *walker, load_command *cmd, off_t offset,
+                       bool swap, void *context) {
+  MachoID *macho_id = (MachoID *)context;
+  off_t seg_offset = 0;
+  size_t seg_size = 0;
+
+  if (cmd->cmd == LC_SEGMENT) {
+    struct segment_command seg;
+
+    if (!walker->ReadBytes(&seg, sizeof(seg), offset))
+      return false;
+
+    if (swap)
+      swap_segment_command(&seg, NXHostByteOrder());
+
+    seg_offset = seg.fileoff;
+    seg_size = seg.filesize;
+  } else if (cmd->cmd == LC_SEGMENT_64) {
+    struct segment_command_64 seg64;
+
+    if (!walker->ReadBytes(&seg64, sizeof(seg64), offset))
+      return false;
+
+    if (swap)
+      swap_segment_command_64(&seg64, NXHostByteOrder());
+
+    seg_offset = seg64.fileoff;
+    seg_size = seg64.filesize;
+  }
+
+  // If this was a non-zero segment, read the bytes, update the hash
+  if (seg_size) {
+    // Read 4k x 2 bytes at a time.  This is faster than just 4k bytes, but
+    // doesn't seem to be an unreasonable size for the stack.
+    unsigned char buffer[4096 * 2];
+    size_t buffer_size;
+    off_t file_offset = seg_offset;
+    while (seg_size > 0) {
+      if (seg_size > sizeof(buffer)) {
+        buffer_size = sizeof(buffer);
+        seg_size -= buffer_size;
+      } else {
+        buffer_size = seg_size;
+        seg_size = 0;
+      }
+
+      if (!walker->ReadBytes(buffer, buffer_size, file_offset))
+        return false;
+
+      macho_id->Update(buffer, buffer_size);
+      file_offset += buffer_size;
+    }
+  }
+
+  // Continue processing
+  return true;
+}
+
+// static
+bool MachoID::UUIDWalkerCB(MachoWalker *walker, load_command *cmd, off_t offset,
+                           bool swap, void *context) {
+  if (cmd->cmd == LC_UUID) {
+    struct uuid_command *uuid_cmd = (struct uuid_command *)context;
+
+    if (!walker->ReadBytes(uuid_cmd, sizeof(struct uuid_command), offset))
+      return false;
+
+    if (swap)
+      swap_uuid_command(uuid_cmd, NXHostByteOrder());
+
+    return false;
+  }
+
+  // Continue processing
+  return true;
+}
+
+// static
+bool MachoID::IDWalkerCB(MachoWalker *walker, load_command *cmd, off_t offset,
+                         bool swap, void *context) {
+  if (cmd->cmd == LC_ID_DYLIB) {
+    struct dylib_command *dylib_cmd = (struct dylib_command *)context;
+
+    if (!walker->ReadBytes(dylib_cmd, sizeof(struct dylib_command), offset))
+      return false;
+
+    if (swap)
+      swap_dylib_command(dylib_cmd, NXHostByteOrder());
+
+    return false;
+  }
+
+  // Continue processing
+  return true;
+}
+
+}  // namespace MacFileUtilities
diff --git a/src/common/mac/macho_id.h b/src/common/mac/macho_id.h
new file mode 100644
index 00000000..c5261255
--- /dev/null
+++ b/src/common/mac/macho_id.h
@@ -0,0 +1,124 @@
+// 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_id.h: Functions to gather identifying information from a macho file
+//
+// Author: Dan Waylonis
+
+#ifndef COMMON_MAC_MACHO_ID_H__
+#define COMMON_MAC_MACHO_ID_H__
+
+#include <limits.h>
+#include <mach-o/loader.h>
+#include <openssl/md5.h>
+#include <openssl/sha.h>
+
+namespace MacFileUtilities {
+
+class MachoWalker;
+
+class MachoID {
+ public:
+  MachoID(const char *path);
+  ~MachoID();
+
+  // For the given |cpu_type|, return a UUID from the LC_UUID command.
+  // Return false if there isn't a LC_UUID command.
+  bool UUIDCommand(int cpu_type, unsigned char identifier[16]);
+
+  // For the given |cpu_type|, return a UUID from the LC_ID_DYLIB command.
+  // Return false if there isn't a LC_ID_DYLIB command.
+  bool IDCommand(int cpu_type, unsigned char identifier[16]);
+
+  // For the given |cpu_type|, return the Adler32 CRC for the mach-o data
+  // segment(s).
+  // Return 0 on error (e.g., if the file is not a mach-o file)
+  uint32_t Adler32(int cpu_type);
+
+  // For the given |cpu_type|, return the MD5 for the mach-o data segment(s).
+  // Return true on success, false otherwise
+  bool MD5(int cpu_type, unsigned char identifier[16]);
+
+  // For the given |cpu_type|, return the SHA1 for the mach-o data segment(s).
+  // Return true on success, false otherwise
+  bool SHA1(int cpu_type, unsigned char identifier[16]);
+
+ private:
+  // Signature of class member function to be called with data read from file
+  typedef void (MachoID::*UpdateFunction)(unsigned char *bytes, size_t size);
+
+  // Update the CRC value by examining |size| |bytes| and applying the algorithm
+  // to each byte.
+  void UpdateCRC(unsigned char *bytes, size_t size);
+
+  // Update the MD5 value by examining |size| |bytes| and applying the algorithm
+  // to each byte.
+  void UpdateMD5(unsigned char *bytes, size_t size);
+
+  // Update the SHA1 value by examining |size| |bytes| and applying the
+  // algorithm to each byte.
+  void UpdateSHA1(unsigned char *bytes, size_t size);
+
+  // Bottleneck for update routines
+  void Update(unsigned char *bytes, size_t size);
+
+  // The callback from the MachoWalker for CRC, MD5, and SHA1
+  static bool WalkerCB(MachoWalker *walker, load_command *cmd, off_t offset,
+                       bool swap, void *context);
+
+  // The callback from the MachoWalker for LC_UUID
+  static bool UUIDWalkerCB(MachoWalker *walker, load_command *cmd, off_t offset,
+                           bool swap, void *context);
+
+  // The callback from the MachoWalker for LC_ID_DYLIB
+  static bool IDWalkerCB(MachoWalker *walker, load_command *cmd, off_t offset,
+                         bool swap, void *context);
+
+  // File path
+  char path_[PATH_MAX];
+
+  // File descriptor
+  int file_;
+
+  // The current crc value
+  uint32_t crc_;
+
+  // The MD5 context
+  MD5_CTX md5_context_;
+
+  // The SHA1 context
+  SHA_CTX sha1_context_;
+
+  // The current update to call from the Update callback
+  UpdateFunction update_function_;
+};
+
+}  // namespace MacFileUtilities
+
+#endif  // COMMON_MAC_MACHO_ID_H__
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
diff --git a/src/common/mac/macho_walker.h b/src/common/mac/macho_walker.h
new file mode 100644
index 00000000..0d55dd79
--- /dev/null
+++ b/src/common/mac/macho_walker.h
@@ -0,0 +1,94 @@
+// 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.h: Iterate over the load commands in a mach-o file
+//
+// Author: Dan Waylonis
+
+#ifndef COMMON_MAC_MACHO_WALKER_H__
+#define COMMON_MAC_MACHO_WALKER_H__
+
+#include <mach-o/loader.h>
+#include <sys/types.h>
+
+namespace MacFileUtilities {
+
+class MachoWalker {
+ public:
+  // A callback function executed when a new load command is read.  If no
+  // further processing of load commands is desired, return false.  Otherwise,
+  // return true.
+  // |cmd| is the current command, and |offset| is the location relative to the
+  // beginning of the file (not header) where the command was read.  If |swap|
+  // is set, then any command data (other than the returned load_command) should
+  // be swapped when read
+  typedef bool (*LoadCommandCallback)(MachoWalker *walker, load_command *cmd,
+                                      off_t offset, bool swap, void *context);
+
+  MachoWalker(const char *path, LoadCommandCallback callback, void *context);
+  MachoWalker(int file_descriptor, LoadCommandCallback callback, void *context);
+  ~MachoWalker();
+
+  // Begin walking the header for |cpu_type|.  If |cpu_type| is 0, then the
+  // native cpu type is used.  Otherwise, accepted values are listed in
+  // /usr/include/mach/machine.h (e.g., CPU_TYPE_X86 or CPU_TYPE_POWERPC).
+  // Returns false if opening the file failed or if the |cpu_type| is not
+  // present in the file.
+  bool WalkHeader(int cpu_type);
+
+  // Locate (if any) the header offset for |cpu_type| and return in |offset|.
+  // Return true if found, false otherwise.
+  bool FindHeader(int cpu_type, off_t &offset);
+
+  // Read |size| bytes from the opened file at |offset| into |buffer|
+  bool ReadBytes(void *buffer, size_t size, off_t offset);
+
+ private:
+  // Validate the |cpu_type|
+  int ValidateCPUType(int cpu_type);
+
+  // Process an individual header starting at |offset| from the start of the
+  // file.  Return true if successful, false otherwise.
+  bool WalkHeaderAtOffset(off_t offset);
+  bool WalkHeader64AtOffset(off_t offset);
+
+  // Bottleneck for walking the load commands
+  bool WalkHeaderCore(off_t offset, uint32_t number_of_commands, bool swap);
+
+  // File descriptor to the opened file
+  int file_;
+
+  // User specified callback & context
+  LoadCommandCallback callback_;
+  void *callback_context_;
+};
+
+}  // namespace MacFileUtilities
+
+#endif  // COMMON_MAC_MACHO_WALKER_H__