payload_generator/generate_delta_main.cc - platform/system/update_engine - Git at Google

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

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

 #include <base/logging.h>
 #include <base/strings/string_number_conversions.h>
 #include <base/strings/string_split.h>
 #include <chromeos/flag_helper.h>

 #include "update_engine/delta_performer.h"
 #include "update_engine/payload_generator/delta_diff_generator.h"
 #include "update_engine/payload_generator/delta_diff_utils.h"
 #include "update_engine/payload_generator/payload_generation_config.h"
 #include "update_engine/payload_generator/payload_signer.h"
 #include "update_engine/payload_verifier.h"
 #include "update_engine/prefs.h"
 #include "update_engine/terminator.h"
 #include "update_engine/update_metadata.pb.h"
 #include "update_engine/utils.h"

 // 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 {

 void ParseSignatureSizes(const string& signature_sizes_flag,
                          vector<int>* signature_sizes) {
   signature_sizes->clear();
   vector<string> split_strings;

   base::SplitString(signature_sizes_flag, ':', &split_strings);
   for (const string& str : split_strings) {
     int size = 0;
     bool parsing_successful = base::StringToInt(str, &size);
     LOG_IF(FATAL, !parsing_successful)
         << "Invalid signature size: " << str;

     LOG_IF(FATAL, size != (2048 / 8)) <<
         "Only signature sizes of 256 bytes are supported.";

     signature_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(const vector<int> &sizes,
                                     const string& out_hash_file,
                                     const string& in_file) {
   LOG(INFO) << "Calculating payload hash for signing.";
   LOG_IF(FATAL, in_file.empty())
       << "Must pass --in_file to calculate hash for signing.";
   LOG_IF(FATAL, out_hash_file.empty())
       << "Must pass --out_hash_file to calculate hash for signing.";

   chromeos::Blob hash;
   bool result = PayloadSigner::HashPayloadForSigning(in_file, sizes,
                                                      &hash);
   CHECK(result);

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


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

   chromeos::Blob hash;
   bool result = PayloadSigner::HashMetadataForSigning(in_file, sizes,
                                                       &hash);
   CHECK(result);

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

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

 void SignPayload(const string& in_file,
                  const string& out_file,
                  const string& signature_file) {
   LOG(INFO) << "Signing payload.";
   LOG_IF(FATAL, in_file.empty())
       << "Must pass --in_file to sign payload.";
   LOG_IF(FATAL, out_file.empty())
       << "Must pass --out_file to sign payload.";
   LOG_IF(FATAL, signature_file.empty())
       << "Must pass --signature_file to sign payload.";
   vector<chromeos::Blob> signatures;
   vector<string> signature_files;
   base::SplitString(signature_file, ':', &signature_files);
   for (const string& signature_file : signature_files) {
     chromeos::Blob signature;
     CHECK(utils::ReadFile(signature_file, &signature));
     signatures.push_back(signature);
   }
   uint64_t final_metadata_size;
   CHECK(PayloadSigner::AddSignatureToPayload(
       in_file, signatures, out_file, &final_metadata_size));
   LOG(INFO) << "Done signing payload. Final metadata size = "
             << final_metadata_size;
 }

 void VerifySignedPayload(const string& in_file,
                          const string& public_key,
                          int public_key_version) {
   LOG(INFO) << "Verifying signed payload.";
   LOG_IF(FATAL, in_file.empty())
       << "Must pass --in_file to verify signed payload.";
   LOG_IF(FATAL, public_key.empty())
       << "Must pass --public_key to verify signed payload.";
   CHECK(PayloadVerifier::VerifySignedPayload(in_file, public_key,
                                              public_key_version));
   LOG(INFO) << "Done verifying signed payload.";
 }

 void ApplyDelta(const string& in_file,
                 const string& old_kernel,
                 const string& old_rootfs,
                 const string& prefs_dir) {
   LOG(INFO) << "Applying delta.";
   LOG_IF(FATAL, old_rootfs.empty())
       << "Must pass --old_image to apply delta.";
   Prefs prefs;
   InstallPlan install_plan;
   LOG(INFO) << "Setting up preferences under: " << prefs_dir;
   LOG_IF(ERROR, !prefs.Init(base::FilePath(prefs_dir)))
       << "Failed to initialize preferences.";
   // Get original checksums
   LOG(INFO) << "Calculating original checksums";
   PartitionInfo kern_info, root_info;
   ImageConfig old_image;
   old_image.kernel.path = old_kernel;
   old_image.rootfs.path = old_rootfs;
   CHECK(old_image.LoadImageSize());
   CHECK(diff_utils::InitializePartitionInfo(old_image.kernel, &kern_info));
   CHECK(diff_utils::InitializePartitionInfo(old_image.rootfs, &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, nullptr, &install_plan);
   CHECK_EQ(performer.Open(old_rootfs.c_str(), 0, 0), 0);
   CHECK(performer.OpenKernel(old_kernel.c_str()));
   chromeos::Blob buf(1024 * 1024);
   int fd = open(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.data(), buf.size(), offset, &bytes_read));
     if (bytes_read == 0)
       break;
     CHECK_EQ(performer.Write(buf.data(), bytes_read), bytes_read);
   }
   CHECK_EQ(performer.Close(), 0);
   DeltaPerformer::ResetUpdateProgress(&prefs, false);
   LOG(INFO) << "Done applying delta.";
 }

 int Main(int argc, char** argv) {
   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, 200 * 1024 * 1024,
                "Payload chunk size (-1 for whole files)");
   DEFINE_uint64(rootfs_partition_size,
                chromeos_update_engine::kRootFSPartitionSize,
                "RootFS partition size for the image once installed");
   DEFINE_int32(minor_version, -1,
                "The minor version of the payload being generated "
                "(-1 means autodetect).");

   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.");

   chromeos::FlagHelper::Init(argc, argv,
       "Generates a payload to provide to ChromeOS' update_engine.\n\n"
       "This tool can create full payloads and also delta payloads if the src\n"
       "image is provided. It also provides debugging options to apply, sign\n"
       "and verify payloads.");
   Terminator::Init();

   logging::LoggingSettings log_settings;
   log_settings.log_file     = "delta_generator.log";
   log_settings.logging_dest = logging::LOG_TO_SYSTEM_DEBUG_LOG;
   log_settings.lock_log     = logging::LOCK_LOG_FILE;
   log_settings.delete_old   = logging::APPEND_TO_OLD_LOG_FILE;

   logging::InitLogging(log_settings);

   vector<int> signature_sizes;
   ParseSignatureSizes(FLAGS_signature_size, &signature_sizes);

   if (!FLAGS_out_hash_file.empty() || !FLAGS_out_metadata_hash_file.empty()) {
     if (!FLAGS_out_hash_file.empty()) {
       CalculatePayloadHashForSigning(signature_sizes, FLAGS_out_hash_file,
                                      FLAGS_in_file);
     }
     if (!FLAGS_out_metadata_hash_file.empty()) {
       CalculateMetadataHashForSigning(signature_sizes,
                                       FLAGS_out_metadata_hash_file,
                                       FLAGS_in_file);
     }
     return 0;
   }
   if (!FLAGS_signature_file.empty()) {
     SignPayload(FLAGS_in_file, FLAGS_out_file, FLAGS_signature_file);
     return 0;
   }
   if (!FLAGS_public_key.empty()) {
     VerifySignedPayload(FLAGS_in_file, FLAGS_public_key,
                         FLAGS_public_key_version);
     return 0;
   }
   if (!FLAGS_in_file.empty()) {
     ApplyDelta(FLAGS_in_file, FLAGS_old_kernel, FLAGS_old_image,
                FLAGS_prefs_dir);
     return 0;
   }

   // A payload generation was requested. Convert the flags to a
   // PayloadGenerationConfig.
   PayloadGenerationConfig payload_config;
   payload_config.source.rootfs.path = FLAGS_old_image;
   payload_config.source.kernel.path = FLAGS_old_kernel;

   payload_config.target.rootfs.path = FLAGS_new_image;
   payload_config.target.kernel.path = FLAGS_new_kernel;

   // Use the default soft_chunk_size defined in the config.
   payload_config.hard_chunk_size = FLAGS_chunk_size;
   payload_config.block_size = kBlockSize;

   // The kernel and rootfs size is never passed to the delta_generator, so we
   // need to detect those from the provided files.
   if (!FLAGS_old_image.empty()) {
     CHECK(payload_config.source.LoadImageSize());
   }
   if (!FLAGS_new_image.empty()) {
     CHECK(payload_config.target.LoadImageSize());
   }

   payload_config.is_delta = !FLAGS_old_image.empty();

   CHECK(!FLAGS_out_file.empty());

   // Ignore failures. These are optional arguments.
   ParseImageInfo(FLAGS_new_channel,
                  FLAGS_new_board,
                  FLAGS_new_version,
                  FLAGS_new_key,
                  FLAGS_new_build_channel,
                  FLAGS_new_build_version,
                  &payload_config.target.image_info);

   // Ignore failures. These are optional arguments.
   ParseImageInfo(FLAGS_old_channel,
                  FLAGS_old_board,
                  FLAGS_old_version,
                  FLAGS_old_key,
                  FLAGS_old_build_channel,
                  FLAGS_old_build_version,
                  &payload_config.source.image_info);

   payload_config.rootfs_partition_size = FLAGS_rootfs_partition_size;

   // Load the rootfs size from verity's kernel command line if rootfs
   // verification is enabled.
   payload_config.source.LoadVerityRootfsSize();
   payload_config.target.LoadVerityRootfsSize();

   if (payload_config.is_delta) {
     // Avoid opening the filesystem interface for full payloads.
     CHECK(payload_config.target.rootfs.OpenFilesystem());
     CHECK(payload_config.target.kernel.OpenFilesystem());
     CHECK(payload_config.source.rootfs.OpenFilesystem());
     CHECK(payload_config.source.kernel.OpenFilesystem());
   }

   if (FLAGS_minor_version == -1) {
     // Autodetect minor_version by looking at the update_engine.conf in the old
     // image.
     if (payload_config.is_delta) {
       CHECK(payload_config.source.rootfs.fs_interface);
       chromeos::KeyValueStore store;
       uint32_t minor_version;
       if (payload_config.source.rootfs.fs_interface->LoadSettings(&store) &&
           utils::GetMinorVersion(store, &minor_version)) {
         payload_config.minor_version = minor_version;
       } else {
         payload_config.minor_version = kInPlaceMinorPayloadVersion;
       }
     } else {
       payload_config.minor_version = DeltaPerformer::kFullPayloadMinorVersion;
     }
     LOG(INFO) << "Auto-detected minor_version=" << payload_config.minor_version;
   } else {
     payload_config.minor_version = FLAGS_minor_version;
     LOG(INFO) << "Using provided minor_version=" << FLAGS_minor_version;
   }

   if (payload_config.is_delta) {
     LOG(INFO) << "Generating delta update";
   } else {
     LOG(INFO) << "Generating full update";
   }

   // From this point, all the options have been parsed.
   if (!payload_config.Validate()) {
     LOG(ERROR) << "Invalid options passed. See errors above.";
     return 1;
   }

   uint64_t metadata_size;
   if (!GenerateUpdatePayloadFile(payload_config,
                                  FLAGS_out_file,
                                  FLAGS_private_key,
                                  &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 <errno.h>
	#include <fcntl.h>
	#include <sys/stat.h>
	#include <sys/types.h>
	#include <unistd.h>

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

	#include <base/logging.h>
	#include <base/strings/string_number_conversions.h>
	#include <base/strings/string_split.h>
	#include <chromeos/flag_helper.h>

	#include "update_engine/delta_performer.h"
	#include "update_engine/payload_generator/delta_diff_generator.h"
	#include "update_engine/payload_generator/delta_diff_utils.h"
	#include "update_engine/payload_generator/payload_generation_config.h"
	#include "update_engine/payload_generator/payload_signer.h"
	#include "update_engine/payload_verifier.h"
	#include "update_engine/prefs.h"
	#include "update_engine/terminator.h"
	#include "update_engine/update_metadata.pb.h"
	#include "update_engine/utils.h"

	// 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 {

	void ParseSignatureSizes(const string& signature_sizes_flag,
	vector<int>* signature_sizes) {
	signature_sizes->clear();
	vector<string> split_strings;

	base::SplitString(signature_sizes_flag, ':', &split_strings);
	for (const string& str : split_strings) {
	int size = 0;
	bool parsing_successful = base::StringToInt(str, &size);
	LOG_IF(FATAL, !parsing_successful)
	<< "Invalid signature size: " << str;

	LOG_IF(FATAL, size != (2048 / 8)) <<
	"Only signature sizes of 256 bytes are supported.";

	signature_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(const vector<int> &sizes,
	const string& out_hash_file,
	const string& in_file) {
	LOG(INFO) << "Calculating payload hash for signing.";
	LOG_IF(FATAL, in_file.empty())
	<< "Must pass --in_file to calculate hash for signing.";
	LOG_IF(FATAL, out_hash_file.empty())
	<< "Must pass --out_hash_file to calculate hash for signing.";

	chromeos::Blob hash;
	bool result = PayloadSigner::HashPayloadForSigning(in_file, sizes,
	&hash);
	CHECK(result);

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


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

	chromeos::Blob hash;
	bool result = PayloadSigner::HashMetadataForSigning(in_file, sizes,
	&hash);
	CHECK(result);

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

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

	void SignPayload(const string& in_file,
	const string& out_file,
	const string& signature_file) {
	LOG(INFO) << "Signing payload.";
	LOG_IF(FATAL, in_file.empty())
	<< "Must pass --in_file to sign payload.";
	LOG_IF(FATAL, out_file.empty())
	<< "Must pass --out_file to sign payload.";
	LOG_IF(FATAL, signature_file.empty())
	<< "Must pass --signature_file to sign payload.";
	vector<chromeos::Blob> signatures;
	vector<string> signature_files;
	base::SplitString(signature_file, ':', &signature_files);
	for (const string& signature_file : signature_files) {
	chromeos::Blob signature;
	CHECK(utils::ReadFile(signature_file, &signature));
	signatures.push_back(signature);
	}
	uint64_t final_metadata_size;
	CHECK(PayloadSigner::AddSignatureToPayload(
	in_file, signatures, out_file, &final_metadata_size));
	LOG(INFO) << "Done signing payload. Final metadata size = "
	<< final_metadata_size;
	}

	void VerifySignedPayload(const string& in_file,
	const string& public_key,
	int public_key_version) {
	LOG(INFO) << "Verifying signed payload.";
	LOG_IF(FATAL, in_file.empty())
	<< "Must pass --in_file to verify signed payload.";
	LOG_IF(FATAL, public_key.empty())
	<< "Must pass --public_key to verify signed payload.";
	CHECK(PayloadVerifier::VerifySignedPayload(in_file, public_key,
	public_key_version));
	LOG(INFO) << "Done verifying signed payload.";
	}

	void ApplyDelta(const string& in_file,
	const string& old_kernel,
	const string& old_rootfs,
	const string& prefs_dir) {
	LOG(INFO) << "Applying delta.";
	LOG_IF(FATAL, old_rootfs.empty())
	<< "Must pass --old_image to apply delta.";
	Prefs prefs;
	InstallPlan install_plan;
	LOG(INFO) << "Setting up preferences under: " << prefs_dir;
	LOG_IF(ERROR, !prefs.Init(base::FilePath(prefs_dir)))
	<< "Failed to initialize preferences.";
	// Get original checksums
	LOG(INFO) << "Calculating original checksums";
	PartitionInfo kern_info, root_info;
	ImageConfig old_image;
	old_image.kernel.path = old_kernel;
	old_image.rootfs.path = old_rootfs;
	CHECK(old_image.LoadImageSize());
	CHECK(diff_utils::InitializePartitionInfo(old_image.kernel, &kern_info));
	CHECK(diff_utils::InitializePartitionInfo(old_image.rootfs, &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, nullptr, &install_plan);
	CHECK_EQ(performer.Open(old_rootfs.c_str(), 0, 0), 0);
	CHECK(performer.OpenKernel(old_kernel.c_str()));
	chromeos::Blob buf(1024 * 1024);
	int fd = open(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.data(), buf.size(), offset, &bytes_read));
	if (bytes_read == 0)
	break;
	CHECK_EQ(performer.Write(buf.data(), bytes_read), bytes_read);
	}
	CHECK_EQ(performer.Close(), 0);
	DeltaPerformer::ResetUpdateProgress(&prefs, false);
	LOG(INFO) << "Done applying delta.";
	}

	int Main(int argc, char** argv) {
	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, 200 * 1024 * 1024,
	"Payload chunk size (-1 for whole files)");
	DEFINE_uint64(rootfs_partition_size,
	chromeos_update_engine::kRootFSPartitionSize,
	"RootFS partition size for the image once installed");
	DEFINE_int32(minor_version, -1,
	"The minor version of the payload being generated "
	"(-1 means autodetect).");

	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.");

	chromeos::FlagHelper::Init(argc, argv,
	"Generates a payload to provide to ChromeOS' update_engine.\n\n"
	"This tool can create full payloads and also delta payloads if the src\n"
	"image is provided. It also provides debugging options to apply, sign\n"
	"and verify payloads.");
	Terminator::Init();

	logging::LoggingSettings log_settings;
	log_settings.log_file = "delta_generator.log";
	log_settings.logging_dest = logging::LOG_TO_SYSTEM_DEBUG_LOG;
	log_settings.lock_log = logging::LOCK_LOG_FILE;
	log_settings.delete_old = logging::APPEND_TO_OLD_LOG_FILE;

	logging::InitLogging(log_settings);

	vector<int> signature_sizes;
	ParseSignatureSizes(FLAGS_signature_size, &signature_sizes);

	if (!FLAGS_out_hash_file.empty() \|\| !FLAGS_out_metadata_hash_file.empty()) {
	if (!FLAGS_out_hash_file.empty()) {
	CalculatePayloadHashForSigning(signature_sizes, FLAGS_out_hash_file,
	FLAGS_in_file);
	}
	if (!FLAGS_out_metadata_hash_file.empty()) {
	CalculateMetadataHashForSigning(signature_sizes,
	FLAGS_out_metadata_hash_file,
	FLAGS_in_file);
	}
	return 0;
	}
	if (!FLAGS_signature_file.empty()) {
	SignPayload(FLAGS_in_file, FLAGS_out_file, FLAGS_signature_file);
	return 0;
	}
	if (!FLAGS_public_key.empty()) {
	VerifySignedPayload(FLAGS_in_file, FLAGS_public_key,
	FLAGS_public_key_version);
	return 0;
	}
	if (!FLAGS_in_file.empty()) {
	ApplyDelta(FLAGS_in_file, FLAGS_old_kernel, FLAGS_old_image,
	FLAGS_prefs_dir);
	return 0;
	}

	// A payload generation was requested. Convert the flags to a
	// PayloadGenerationConfig.
	PayloadGenerationConfig payload_config;
	payload_config.source.rootfs.path = FLAGS_old_image;
	payload_config.source.kernel.path = FLAGS_old_kernel;

	payload_config.target.rootfs.path = FLAGS_new_image;
	payload_config.target.kernel.path = FLAGS_new_kernel;

	// Use the default soft_chunk_size defined in the config.
	payload_config.hard_chunk_size = FLAGS_chunk_size;
	payload_config.block_size = kBlockSize;

	// The kernel and rootfs size is never passed to the delta_generator, so we
	// need to detect those from the provided files.
	if (!FLAGS_old_image.empty()) {
	CHECK(payload_config.source.LoadImageSize());
	}
	if (!FLAGS_new_image.empty()) {
	CHECK(payload_config.target.LoadImageSize());
	}

	payload_config.is_delta = !FLAGS_old_image.empty();

	CHECK(!FLAGS_out_file.empty());

	// Ignore failures. These are optional arguments.
	ParseImageInfo(FLAGS_new_channel,
	FLAGS_new_board,
	FLAGS_new_version,
	FLAGS_new_key,
	FLAGS_new_build_channel,
	FLAGS_new_build_version,
	&payload_config.target.image_info);

	// Ignore failures. These are optional arguments.
	ParseImageInfo(FLAGS_old_channel,
	FLAGS_old_board,
	FLAGS_old_version,
	FLAGS_old_key,
	FLAGS_old_build_channel,
	FLAGS_old_build_version,
	&payload_config.source.image_info);

	payload_config.rootfs_partition_size = FLAGS_rootfs_partition_size;

	// Load the rootfs size from verity's kernel command line if rootfs
	// verification is enabled.
	payload_config.source.LoadVerityRootfsSize();
	payload_config.target.LoadVerityRootfsSize();

	if (payload_config.is_delta) {
	// Avoid opening the filesystem interface for full payloads.
	CHECK(payload_config.target.rootfs.OpenFilesystem());
	CHECK(payload_config.target.kernel.OpenFilesystem());
	CHECK(payload_config.source.rootfs.OpenFilesystem());
	CHECK(payload_config.source.kernel.OpenFilesystem());
	}

	if (FLAGS_minor_version == -1) {
	// Autodetect minor_version by looking at the update_engine.conf in the old
	// image.
	if (payload_config.is_delta) {
	CHECK(payload_config.source.rootfs.fs_interface);
	chromeos::KeyValueStore store;
	uint32_t minor_version;
	if (payload_config.source.rootfs.fs_interface->LoadSettings(&store) &&
	utils::GetMinorVersion(store, &minor_version)) {
	payload_config.minor_version = minor_version;
	} else {
	payload_config.minor_version = kInPlaceMinorPayloadVersion;
	}
	} else {
	payload_config.minor_version = DeltaPerformer::kFullPayloadMinorVersion;
	}
	LOG(INFO) << "Auto-detected minor_version=" << payload_config.minor_version;
	} else {
	payload_config.minor_version = FLAGS_minor_version;
	LOG(INFO) << "Using provided minor_version=" << FLAGS_minor_version;
	}

	if (payload_config.is_delta) {
	LOG(INFO) << "Generating delta update";
	} else {
	LOG(INFO) << "Generating full update";
	}

	// From this point, all the options have been parsed.
	if (!payload_config.Validate()) {
	LOG(ERROR) << "Invalid options passed. See errors above.";
	return 1;
	}

	uint64_t metadata_size;
	if (!GenerateUpdatePayloadFile(payload_config,
	FLAGS_out_file,
	FLAGS_private_key,
	&metadata_size)) {
	return 1;
	}

	return 0;
	}

	} // namespace

	} // namespace chromeos_update_engine

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