generate_delta_main.cc - SHIFTPHONES/android_system_update_engine - Gitiles

 // Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include <sys/types.h>
 #include <sys/stat.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <unistd.h>

 #include <set>
 #include <string>
 #include <vector>

 #include <base/command_line.h>
 #include <base/logging.h>
 #include <base/string_number_conversions.h>
 #include <base/string_split.h>
 #include <gflags/gflags.h>
 #include <glib.h>

 #include "update_engine/delta_diff_generator.h"
 #include "update_engine/delta_performer.h"
 #include "update_engine/payload_signer.h"
 #include "update_engine/prefs.h"
 #include "update_engine/subprocess.h"
 #include "update_engine/terminator.h"
 #include "update_engine/update_metadata.pb.h"
 #include "update_engine/utils.h"

 DEFINE_string(old_dir, "",
               "Directory where the old rootfs is loop mounted read-only");
 DEFINE_string(new_dir, "",
               "Directory where the new rootfs is loop mounted read-only");
 DEFINE_string(old_image, "", "Path to the old rootfs");
 DEFINE_string(new_image, "", "Path to the new rootfs");
 DEFINE_string(old_kernel, "", "Path to the old kernel partition image");
 DEFINE_string(new_kernel, "", "Path to the new kernel partition image");
 DEFINE_string(in_file, "",
               "Path to input delta payload file used to hash/sign payloads "
               "and apply delta over old_image (for debugging)");
 DEFINE_string(out_file, "", "Path to output delta payload file");
 DEFINE_string(out_hash_file, "", "Path to output hash file");
 DEFINE_string(out_metadata_hash_file, "", "Path to output metadata hash file");
 DEFINE_string(private_key, "", "Path to private key in .pem format");
 DEFINE_string(public_key, "", "Path to public key in .pem format");
 DEFINE_int32(public_key_version,
              chromeos_update_engine::kSignatureMessageCurrentVersion,
              "Key-check version # of client");
 DEFINE_string(prefs_dir, "/tmp/update_engine_prefs",
               "Preferences directory, used with apply_delta");
 DEFINE_string(signature_size, "",
               "Raw signature size used for hash calculation. "
               "You may pass in multiple sizes by colon separating them. E.g. "
               "2048:2048:4096 will assume 3 signatures, the first two with "
               "2048 size and the last 4096.");
 DEFINE_string(signature_file, "",
               "Raw signature file to sign payload with. To pass multiple "
               "signatures, use a single argument with a colon between paths, "
               "e.g. /path/to/sig:/path/to/next:/path/to/last_sig . Each "
               "signature will be assigned a client version, starting from "
               "kSignatureOriginalVersion.");
 DEFINE_int32(chunk_size, -1, "Payload chunk size (-1 -- no limit/default)");
 DEFINE_int64(rootfs_partition_size,
              chromeos_update_engine::kRootFSPartitionSize,
              "RootFS partition size for the image once installed");

 DEFINE_string(old_channel, "",
               "The channel for the old image. 'dev-channel', 'npo-channel', "
               "etc. Ignored, except during delta generation.");
 DEFINE_string(old_board, "",
               "The board for the old image. 'x86-mario', 'lumpy', "
               "etc. Ignored, except during delta generation.");
 DEFINE_string(old_version, "",
               "The build version of the old image. 1.2.3, etc.");
 DEFINE_string(old_key, "",
               "The key used to sign the old image. 'premp', 'mp', 'mp-v3',"
               " etc");
 DEFINE_string(old_build_channel, "",
               "The channel for the build of the old image. 'dev-channel', "
               "etc, but will never contain special channels such as "
               "'npo-channel'. Ignored, except during delta generation.");
 DEFINE_string(old_build_version, "",
               "The version of the build containing the old image.");

 DEFINE_string(new_channel, "",
               "The channel for the new image. 'dev-channel', 'npo-channel', "
               "etc. Ignored, except during delta generation.");
 DEFINE_string(new_board, "",
               "The board for the new image. 'x86-mario', 'lumpy', "
               "etc. Ignored, except during delta generation.");
 DEFINE_string(new_version, "",
               "The build version of the new image. 1.2.3, etc.");
 DEFINE_string(new_key, "",
               "The key used to sign the new image. 'premp', 'mp', 'mp-v3',"
               " etc");
 DEFINE_string(new_build_channel, "",
               "The channel for the build of the new image. 'dev-channel', "
               "etc, but will never contain special channels such as "
               "'npo-channel'. Ignored, except during delta generation.");
 DEFINE_string(new_build_version, "",
               "The version of the build containing the new image.");

 // This file contains a simple program that takes an old path, a new path,
 // and an output file as arguments and the path to an output file and
 // generates a delta that can be sent to Chrome OS clients.

 using std::set;
 using std::string;
 using std::vector;

 namespace chromeos_update_engine {

 namespace {

 bool IsDir(const char* path) {
   struct stat stbuf;
   TEST_AND_RETURN_FALSE_ERRNO(lstat(path, &stbuf) == 0);
   return S_ISDIR(stbuf.st_mode);
 }

 void ParseSignatureSizes(vector<int>* sizes) {
   LOG_IF(FATAL, FLAGS_signature_size.empty())
       << "Must pass --signature_size to calculate hash for signing.";
   vector<string> strsizes;
   base::SplitString(FLAGS_signature_size, ':', &strsizes);
   for (vector<string>::iterator it = strsizes.begin(), e = strsizes.end();
        it != e; ++it) {
     int size = 0;
     bool parsing_successful = base::StringToInt(*it, &size);
     LOG_IF(FATAL, !parsing_successful)
         << "Invalid signature size: " << *it;
     sizes->push_back(size);
   }
 }


 bool ParseImageInfo(const string& channel,
                     const string& board,
                     const string& version,
                     const string& key,
                     const string& build_channel,
                     const string& build_version,
                     ImageInfo* image_info) {

   // All of these arguments should be present or missing.
   bool empty = channel.empty();

   CHECK_EQ(channel.empty(), empty);
   CHECK_EQ(board.empty(), empty);
   CHECK_EQ(version.empty(), empty);
   CHECK_EQ(key.empty(), empty);

   if (empty)
     return false;

   image_info->set_channel(channel);
   image_info->set_board(board);
   image_info->set_version(version);
   image_info->set_key(key);

   image_info->set_build_channel(
       build_channel.empty() ? channel : build_channel);

   image_info->set_build_version(
       build_version.empty() ? version : build_version);

   return true;
 }


 void CalculatePayloadHashForSigning() {
   LOG(INFO) << "Calculating payload hash for signing.";
   LOG_IF(FATAL, FLAGS_in_file.empty())
       << "Must pass --in_file to calculate hash for signing.";
   LOG_IF(FATAL, FLAGS_out_hash_file.empty())
       << "Must pass --out_hash_file to calculate hash for signing.";
   vector<int> sizes;
   ParseSignatureSizes(&sizes);

   vector<char> hash;
   bool result = PayloadSigner::HashPayloadForSigning(FLAGS_in_file, sizes,
                                                      &hash);
   CHECK(result);

   result = utils::WriteFile(FLAGS_out_hash_file.c_str(), hash.data(),
                             hash.size());
   CHECK(result);
   LOG(INFO) << "Done calculating payload hash for signing.";
 }


 void CalculateMetadataHashForSigning() {
   LOG(INFO) << "Calculating metadata hash for signing.";
   LOG_IF(FATAL, FLAGS_in_file.empty())
       << "Must pass --in_file to calculate metadata hash for signing.";
   LOG_IF(FATAL, FLAGS_out_metadata_hash_file.empty())
       << "Must pass --out_metadata_hash_file to calculate metadata hash.";
   vector<int> sizes;
   ParseSignatureSizes(&sizes);

   vector<char> hash;
   bool result = PayloadSigner::HashMetadataForSigning(FLAGS_in_file, &hash);
   CHECK(result);

   result = utils::WriteFile(FLAGS_out_metadata_hash_file.c_str(), hash.data(),
                             hash.size());
   CHECK(result);

   LOG(INFO) << "Done calculating metadata hash for signing.";
 }

 void SignPayload() {
   LOG(INFO) << "Signing payload.";
   LOG_IF(FATAL, FLAGS_in_file.empty())
       << "Must pass --in_file to sign payload.";
   LOG_IF(FATAL, FLAGS_out_file.empty())
       << "Must pass --out_file to sign payload.";
   LOG_IF(FATAL, FLAGS_signature_file.empty())
       << "Must pass --signature_file to sign payload.";
   vector<vector<char> > signatures;
   vector<string> signature_files;
   base::SplitString(FLAGS_signature_file, ':', &signature_files);
   for (vector<string>::iterator it = signature_files.begin(),
            e = signature_files.end(); it != e; ++it) {
     vector<char> signature;
     CHECK(utils::ReadFile(*it, &signature));
     signatures.push_back(signature);
   }
   uint64_t final_metadata_size;
   CHECK(PayloadSigner::AddSignatureToPayload(
       FLAGS_in_file, signatures, FLAGS_out_file, &final_metadata_size));
   LOG(INFO) << "Done signing payload. Final metadata size = "
             << final_metadata_size;
 }

 void VerifySignedPayload() {
   LOG(INFO) << "Verifying signed payload.";
   LOG_IF(FATAL, FLAGS_in_file.empty())
       << "Must pass --in_file to verify signed payload.";
   LOG_IF(FATAL, FLAGS_public_key.empty())
       << "Must pass --public_key to verify signed payload.";
   CHECK(PayloadSigner::VerifySignedPayload(FLAGS_in_file, FLAGS_public_key,
                                            FLAGS_public_key_version));
   LOG(INFO) << "Done verifying signed payload.";
 }

 void ApplyDelta() {
   LOG(INFO) << "Applying delta.";
   LOG_IF(FATAL, FLAGS_old_image.empty())
       << "Must pass --old_image to apply delta.";
   Prefs prefs;
   InstallPlan install_plan;
   LOG(INFO) << "Setting up preferences under: " << FLAGS_prefs_dir;
   LOG_IF(ERROR, !prefs.Init(FilePath(FLAGS_prefs_dir)))
       << "Failed to initialize preferences.";
   // Get original checksums
   LOG(INFO) << "Calculating original checksums";
   PartitionInfo kern_info, root_info;
   CHECK(DeltaDiffGenerator::InitializePartitionInfo(true,  // is_kernel
                                                     FLAGS_old_kernel,
                                                     &kern_info));
   CHECK(DeltaDiffGenerator::InitializePartitionInfo(false,  // is_kernel
                                                     FLAGS_old_image,
                                                     &root_info));
   install_plan.kernel_hash.assign(kern_info.hash().begin(),
                                   kern_info.hash().end());
   install_plan.rootfs_hash.assign(root_info.hash().begin(),
                                   root_info.hash().end());
   DeltaPerformer performer(&prefs, NULL, &install_plan);
   CHECK_EQ(performer.Open(FLAGS_old_image.c_str(), 0, 0), 0);
   CHECK(performer.OpenKernel(FLAGS_old_kernel.c_str()));
   vector<char> buf(1024 * 1024);
   int fd = open(FLAGS_in_file.c_str(), O_RDONLY, 0);
   CHECK_GE(fd, 0);
   ScopedFdCloser fd_closer(&fd);
   for (off_t offset = 0;; offset += buf.size()) {
     ssize_t bytes_read;
     CHECK(utils::PReadAll(fd, &buf[0], buf.size(), offset, &bytes_read));
     if (bytes_read == 0)
       break;
     CHECK_EQ(performer.Write(&buf[0], bytes_read), bytes_read);
   }
   CHECK_EQ(performer.Close(), 0);
   DeltaPerformer::ResetUpdateProgress(&prefs, false);
   LOG(INFO) << "Done applying delta.";
 }

 int Main(int argc, char** argv) {
   g_thread_init(NULL);
   google::ParseCommandLineFlags(&argc, &argv, true);
   CommandLine::Init(argc, argv);
   Terminator::Init();
   Subprocess::Init();
   logging::InitLogging("delta_generator.log",
                        logging::LOG_ONLY_TO_SYSTEM_DEBUG_LOG,
                        logging::DONT_LOCK_LOG_FILE,
                        logging::APPEND_TO_OLD_LOG_FILE,
                        logging::DISABLE_DCHECK_FOR_NON_OFFICIAL_RELEASE_BUILDS);
   if (!FLAGS_signature_size.empty()) {
     bool work_done = false;
     if (!FLAGS_out_hash_file.empty()) {
       CalculatePayloadHashForSigning();
       work_done = true;
     }
     if (!FLAGS_out_metadata_hash_file.empty()) {
       CalculateMetadataHashForSigning();
       work_done = true;
     }
     if (!work_done) {
       LOG(FATAL) << "Neither payload hash file nor metadata hash file supplied";
     }
     return 0;
   }
   if (!FLAGS_signature_file.empty()) {
     SignPayload();
     return 0;
   }
   if (!FLAGS_public_key.empty()) {
     VerifySignedPayload();
     return 0;
   }
   if (!FLAGS_in_file.empty()) {
     ApplyDelta();
     return 0;
   }
   CHECK(!FLAGS_new_image.empty());
   CHECK(!FLAGS_out_file.empty());
   CHECK(!FLAGS_new_kernel.empty());

   bool is_delta = !FLAGS_old_image.empty();

   ImageInfo old_image_info;
   ImageInfo new_image_info;

   // TODO(dgarrett) Check the result is True when these args are required.
   ParseImageInfo(FLAGS_new_channel,
                  FLAGS_new_board,
                  FLAGS_new_version,
                  FLAGS_new_key,
                  FLAGS_new_build_channel,
                  FLAGS_new_build_version,
                  &new_image_info);

   CHECK(is_delta || !ParseImageInfo(FLAGS_old_channel,
                                     FLAGS_old_board,
                                     FLAGS_old_version,
                                     FLAGS_old_key,
                                     FLAGS_old_build_channel,
                                     FLAGS_old_build_version,
                                     &old_image_info));


   if (is_delta) {
     LOG(INFO) << "Generating delta update";
     CHECK(!FLAGS_old_dir.empty());
     CHECK(!FLAGS_new_dir.empty());
     if ((!IsDir(FLAGS_old_dir.c_str())) || (!IsDir(FLAGS_new_dir.c_str()))) {
       LOG(FATAL) << "old_dir or new_dir not directory";
     }
   } else {
     LOG(INFO) << "Generating full update";
   }

   uint64_t metadata_size;
   if (!DeltaDiffGenerator::GenerateDeltaUpdateFile(
       FLAGS_old_dir,
       FLAGS_old_image,
       FLAGS_new_dir,
       FLAGS_new_image,
       FLAGS_old_kernel,
       FLAGS_new_kernel,
       FLAGS_out_file,
       FLAGS_private_key,
       FLAGS_chunk_size,
       FLAGS_rootfs_partition_size,
       is_delta ? &old_image_info : NULL,
       &new_image_info,
       &metadata_size)) {
     return 1;
   }
   return 0;
 }

 }  // namespace {}

 }  // namespace chromeos_update_engine

 int main(int argc, char** argv) {
   return chromeos_update_engine::Main(argc, argv);
 }
	// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include <sys/types.h>
	#include <sys/stat.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <unistd.h>

	#include <set>
	#include <string>
	#include <vector>

	#include <base/command_line.h>
	#include <base/logging.h>
	#include <base/string_number_conversions.h>
	#include <base/string_split.h>
	#include <gflags/gflags.h>
	#include <glib.h>

	#include "update_engine/delta_diff_generator.h"
	#include "update_engine/delta_performer.h"
	#include "update_engine/payload_signer.h"
	#include "update_engine/prefs.h"
	#include "update_engine/subprocess.h"
	#include "update_engine/terminator.h"
	#include "update_engine/update_metadata.pb.h"
	#include "update_engine/utils.h"

	DEFINE_string(old_dir, "",
	"Directory where the old rootfs is loop mounted read-only");
	DEFINE_string(new_dir, "",
	"Directory where the new rootfs is loop mounted read-only");
	DEFINE_string(old_image, "", "Path to the old rootfs");
	DEFINE_string(new_image, "", "Path to the new rootfs");
	DEFINE_string(old_kernel, "", "Path to the old kernel partition image");
	DEFINE_string(new_kernel, "", "Path to the new kernel partition image");
	DEFINE_string(in_file, "",
	"Path to input delta payload file used to hash/sign payloads "
	"and apply delta over old_image (for debugging)");
	DEFINE_string(out_file, "", "Path to output delta payload file");
	DEFINE_string(out_hash_file, "", "Path to output hash file");
	DEFINE_string(out_metadata_hash_file, "", "Path to output metadata hash file");
	DEFINE_string(private_key, "", "Path to private key in .pem format");
	DEFINE_string(public_key, "", "Path to public key in .pem format");
	DEFINE_int32(public_key_version,
	chromeos_update_engine::kSignatureMessageCurrentVersion,
	"Key-check version # of client");
	DEFINE_string(prefs_dir, "/tmp/update_engine_prefs",
	"Preferences directory, used with apply_delta");
	DEFINE_string(signature_size, "",
	"Raw signature size used for hash calculation. "
	"You may pass in multiple sizes by colon separating them. E.g. "
	"2048:2048:4096 will assume 3 signatures, the first two with "
	"2048 size and the last 4096.");
	DEFINE_string(signature_file, "",
	"Raw signature file to sign payload with. To pass multiple "
	"signatures, use a single argument with a colon between paths, "
	"e.g. /path/to/sig:/path/to/next:/path/to/last_sig . Each "
	"signature will be assigned a client version, starting from "
	"kSignatureOriginalVersion.");
	DEFINE_int32(chunk_size, -1, "Payload chunk size (-1 -- no limit/default)");
	DEFINE_int64(rootfs_partition_size,
	chromeos_update_engine::kRootFSPartitionSize,
	"RootFS partition size for the image once installed");

	DEFINE_string(old_channel, "",
	"The channel for the old image. 'dev-channel', 'npo-channel', "
	"etc. Ignored, except during delta generation.");
	DEFINE_string(old_board, "",
	"The board for the old image. 'x86-mario', 'lumpy', "
	"etc. Ignored, except during delta generation.");
	DEFINE_string(old_version, "",
	"The build version of the old image. 1.2.3, etc.");
	DEFINE_string(old_key, "",
	"The key used to sign the old image. 'premp', 'mp', 'mp-v3',"
	" etc");
	DEFINE_string(old_build_channel, "",
	"The channel for the build of the old image. 'dev-channel', "
	"etc, but will never contain special channels such as "
	"'npo-channel'. Ignored, except during delta generation.");
	DEFINE_string(old_build_version, "",
	"The version of the build containing the old image.");

	DEFINE_string(new_channel, "",
	"The channel for the new image. 'dev-channel', 'npo-channel', "
	"etc. Ignored, except during delta generation.");
	DEFINE_string(new_board, "",
	"The board for the new image. 'x86-mario', 'lumpy', "
	"etc. Ignored, except during delta generation.");
	DEFINE_string(new_version, "",
	"The build version of the new image. 1.2.3, etc.");
	DEFINE_string(new_key, "",
	"The key used to sign the new image. 'premp', 'mp', 'mp-v3',"
	" etc");
	DEFINE_string(new_build_channel, "",
	"The channel for the build of the new image. 'dev-channel', "
	"etc, but will never contain special channels such as "
	"'npo-channel'. Ignored, except during delta generation.");
	DEFINE_string(new_build_version, "",
	"The version of the build containing the new image.");

	// This file contains a simple program that takes an old path, a new path,
	// and an output file as arguments and the path to an output file and
	// generates a delta that can be sent to Chrome OS clients.

	using std::set;
	using std::string;
	using std::vector;

	namespace chromeos_update_engine {

	namespace {

	bool IsDir(const char* path) {
	struct stat stbuf;
	TEST_AND_RETURN_FALSE_ERRNO(lstat(path, &stbuf) == 0);
	return S_ISDIR(stbuf.st_mode);
	}

	void ParseSignatureSizes(vector<int>* sizes) {
	LOG_IF(FATAL, FLAGS_signature_size.empty())
	<< "Must pass --signature_size to calculate hash for signing.";
	vector<string> strsizes;
	base::SplitString(FLAGS_signature_size, ':', &strsizes);
	for (vector<string>::iterator it = strsizes.begin(), e = strsizes.end();
	it != e; ++it) {
	int size = 0;
	bool parsing_successful = base::StringToInt(*it, &size);
	LOG_IF(FATAL, !parsing_successful)
	<< "Invalid signature size: " << *it;
	sizes->push_back(size);
	}
	}


	bool ParseImageInfo(const string& channel,
	const string& board,
	const string& version,
	const string& key,
	const string& build_channel,
	const string& build_version,
	ImageInfo* image_info) {

	// All of these arguments should be present or missing.
	bool empty = channel.empty();

	CHECK_EQ(channel.empty(), empty);
	CHECK_EQ(board.empty(), empty);
	CHECK_EQ(version.empty(), empty);
	CHECK_EQ(key.empty(), empty);

	if (empty)
	return false;

	image_info->set_channel(channel);
	image_info->set_board(board);
	image_info->set_version(version);
	image_info->set_key(key);

	image_info->set_build_channel(
	build_channel.empty() ? channel : build_channel);

	image_info->set_build_version(
	build_version.empty() ? version : build_version);

	return true;
	}


	void CalculatePayloadHashForSigning() {
	LOG(INFO) << "Calculating payload hash for signing.";
	LOG_IF(FATAL, FLAGS_in_file.empty())
	<< "Must pass --in_file to calculate hash for signing.";
	LOG_IF(FATAL, FLAGS_out_hash_file.empty())
	<< "Must pass --out_hash_file to calculate hash for signing.";
	vector<int> sizes;
	ParseSignatureSizes(&sizes);

	vector<char> hash;
	bool result = PayloadSigner::HashPayloadForSigning(FLAGS_in_file, sizes,
	&hash);
	CHECK(result);

	result = utils::WriteFile(FLAGS_out_hash_file.c_str(), hash.data(),
	hash.size());
	CHECK(result);
	LOG(INFO) << "Done calculating payload hash for signing.";
	}


	void CalculateMetadataHashForSigning() {
	LOG(INFO) << "Calculating metadata hash for signing.";
	LOG_IF(FATAL, FLAGS_in_file.empty())
	<< "Must pass --in_file to calculate metadata hash for signing.";
	LOG_IF(FATAL, FLAGS_out_metadata_hash_file.empty())
	<< "Must pass --out_metadata_hash_file to calculate metadata hash.";
	vector<int> sizes;
	ParseSignatureSizes(&sizes);

	vector<char> hash;
	bool result = PayloadSigner::HashMetadataForSigning(FLAGS_in_file, &hash);
	CHECK(result);

	result = utils::WriteFile(FLAGS_out_metadata_hash_file.c_str(), hash.data(),
	hash.size());
	CHECK(result);

	LOG(INFO) << "Done calculating metadata hash for signing.";
	}

	void SignPayload() {
	LOG(INFO) << "Signing payload.";
	LOG_IF(FATAL, FLAGS_in_file.empty())
	<< "Must pass --in_file to sign payload.";
	LOG_IF(FATAL, FLAGS_out_file.empty())
	<< "Must pass --out_file to sign payload.";
	LOG_IF(FATAL, FLAGS_signature_file.empty())
	<< "Must pass --signature_file to sign payload.";
	vector<vector<char> > signatures;
	vector<string> signature_files;
	base::SplitString(FLAGS_signature_file, ':', &signature_files);
	for (vector<string>::iterator it = signature_files.begin(),
	e = signature_files.end(); it != e; ++it) {
	vector<char> signature;
	CHECK(utils::ReadFile(*it, &signature));
	signatures.push_back(signature);
	}
	uint64_t final_metadata_size;
	CHECK(PayloadSigner::AddSignatureToPayload(
	FLAGS_in_file, signatures, FLAGS_out_file, &final_metadata_size));
	LOG(INFO) << "Done signing payload. Final metadata size = "
	<< final_metadata_size;
	}

	void VerifySignedPayload() {
	LOG(INFO) << "Verifying signed payload.";
	LOG_IF(FATAL, FLAGS_in_file.empty())
	<< "Must pass --in_file to verify signed payload.";
	LOG_IF(FATAL, FLAGS_public_key.empty())
	<< "Must pass --public_key to verify signed payload.";
	CHECK(PayloadSigner::VerifySignedPayload(FLAGS_in_file, FLAGS_public_key,
	FLAGS_public_key_version));
	LOG(INFO) << "Done verifying signed payload.";
	}

	void ApplyDelta() {
	LOG(INFO) << "Applying delta.";
	LOG_IF(FATAL, FLAGS_old_image.empty())
	<< "Must pass --old_image to apply delta.";
	Prefs prefs;
	InstallPlan install_plan;
	LOG(INFO) << "Setting up preferences under: " << FLAGS_prefs_dir;
	LOG_IF(ERROR, !prefs.Init(FilePath(FLAGS_prefs_dir)))
	<< "Failed to initialize preferences.";
	// Get original checksums
	LOG(INFO) << "Calculating original checksums";
	PartitionInfo kern_info, root_info;
	CHECK(DeltaDiffGenerator::InitializePartitionInfo(true, // is_kernel
	FLAGS_old_kernel,
	&kern_info));
	CHECK(DeltaDiffGenerator::InitializePartitionInfo(false, // is_kernel
	FLAGS_old_image,
	&root_info));
	install_plan.kernel_hash.assign(kern_info.hash().begin(),
	kern_info.hash().end());
	install_plan.rootfs_hash.assign(root_info.hash().begin(),
	root_info.hash().end());
	DeltaPerformer performer(&prefs, NULL, &install_plan);
	CHECK_EQ(performer.Open(FLAGS_old_image.c_str(), 0, 0), 0);
	CHECK(performer.OpenKernel(FLAGS_old_kernel.c_str()));
	vector<char> buf(1024 * 1024);
	int fd = open(FLAGS_in_file.c_str(), O_RDONLY, 0);
	CHECK_GE(fd, 0);
	ScopedFdCloser fd_closer(&fd);
	for (off_t offset = 0;; offset += buf.size()) {
	ssize_t bytes_read;
	CHECK(utils::PReadAll(fd, &buf[0], buf.size(), offset, &bytes_read));
	if (bytes_read == 0)
	break;
	CHECK_EQ(performer.Write(&buf[0], bytes_read), bytes_read);
	}
	CHECK_EQ(performer.Close(), 0);
	DeltaPerformer::ResetUpdateProgress(&prefs, false);
	LOG(INFO) << "Done applying delta.";
	}

	int Main(int argc, char** argv) {
	g_thread_init(NULL);
	google::ParseCommandLineFlags(&argc, &argv, true);
	CommandLine::Init(argc, argv);
	Terminator::Init();
	Subprocess::Init();
	logging::InitLogging("delta_generator.log",
	logging::LOG_ONLY_TO_SYSTEM_DEBUG_LOG,
	logging::DONT_LOCK_LOG_FILE,
	logging::APPEND_TO_OLD_LOG_FILE,
	logging::DISABLE_DCHECK_FOR_NON_OFFICIAL_RELEASE_BUILDS);
	if (!FLAGS_signature_size.empty()) {
	bool work_done = false;
	if (!FLAGS_out_hash_file.empty()) {
	CalculatePayloadHashForSigning();
	work_done = true;
	}
	if (!FLAGS_out_metadata_hash_file.empty()) {
	CalculateMetadataHashForSigning();
	work_done = true;
	}
	if (!work_done) {
	LOG(FATAL) << "Neither payload hash file nor metadata hash file supplied";
	}
	return 0;
	}
	if (!FLAGS_signature_file.empty()) {
	SignPayload();
	return 0;
	}
	if (!FLAGS_public_key.empty()) {
	VerifySignedPayload();
	return 0;
	}
	if (!FLAGS_in_file.empty()) {
	ApplyDelta();
	return 0;
	}
	CHECK(!FLAGS_new_image.empty());
	CHECK(!FLAGS_out_file.empty());
	CHECK(!FLAGS_new_kernel.empty());

	bool is_delta = !FLAGS_old_image.empty();

	ImageInfo old_image_info;
	ImageInfo new_image_info;

	// TODO(dgarrett) Check the result is True when these args are required.
	ParseImageInfo(FLAGS_new_channel,
	FLAGS_new_board,
	FLAGS_new_version,
	FLAGS_new_key,
	FLAGS_new_build_channel,
	FLAGS_new_build_version,
	&new_image_info);

	CHECK(is_delta \|\| !ParseImageInfo(FLAGS_old_channel,
	FLAGS_old_board,
	FLAGS_old_version,
	FLAGS_old_key,
	FLAGS_old_build_channel,
	FLAGS_old_build_version,
	&old_image_info));


	if (is_delta) {
	LOG(INFO) << "Generating delta update";
	CHECK(!FLAGS_old_dir.empty());
	CHECK(!FLAGS_new_dir.empty());
	if ((!IsDir(FLAGS_old_dir.c_str())) \|\| (!IsDir(FLAGS_new_dir.c_str()))) {
	LOG(FATAL) << "old_dir or new_dir not directory";
	}
	} else {
	LOG(INFO) << "Generating full update";
	}

	uint64_t metadata_size;
	if (!DeltaDiffGenerator::GenerateDeltaUpdateFile(
	FLAGS_old_dir,
	FLAGS_old_image,
	FLAGS_new_dir,
	FLAGS_new_image,
	FLAGS_old_kernel,
	FLAGS_new_kernel,
	FLAGS_out_file,
	FLAGS_private_key,
	FLAGS_chunk_size,
	FLAGS_rootfs_partition_size,
	is_delta ? &old_image_info : NULL,
	&new_image_info,
	&metadata_size)) {
	return 1;
	}
	return 0;
	}

	} // namespace {}

	} // namespace chromeos_update_engine

	int main(int argc, char** argv) {
	return chromeos_update_engine::Main(argc, argv);
	}