install.cpp - android_bootable_recovery - Gitiles

 /*
  * Copyright (C) 2007 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "install.h"

 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
 #include <limits.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <unistd.h>

 #include <chrono>
 #include <limits>
 #include <map>
 #include <string>
 #include <vector>

 #include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/parsedouble.h>
 #include <android-base/parseint.h>
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
 #include <ziparchive/zip_archive.h>

 #include "common.h"
 #include "error_code.h"
 #include "minui/minui.h"
 #include "otautil/SysUtil.h"
 #include "roots.h"
 #include "ui.h"
 #include "verifier.h"

 #define ASSUMED_UPDATE_BINARY_NAME  "META-INF/com/google/android/update-binary"
 static constexpr const char* AB_OTA_PAYLOAD_PROPERTIES = "payload_properties.txt";
 static constexpr const char* AB_OTA_PAYLOAD = "payload.bin";
 #define PUBLIC_KEYS_FILE "/res/keys"
 static constexpr const char* METADATA_PATH = "META-INF/com/android/metadata";
 static constexpr const char* UNCRYPT_STATUS = "/cache/recovery/uncrypt_status";

 // Default allocation of progress bar segments to operations
 static constexpr int VERIFICATION_PROGRESS_TIME = 60;
 static constexpr float VERIFICATION_PROGRESS_FRACTION = 0.25;
 static constexpr float DEFAULT_FILES_PROGRESS_FRACTION = 0.4;
 static constexpr float DEFAULT_IMAGE_PROGRESS_FRACTION = 0.1;

 // This function parses and returns the build.version.incremental
 static int parse_build_number(const std::string& str) {
     size_t pos = str.find('=');
     if (pos != std::string::npos) {
         std::string num_string = android::base::Trim(str.substr(pos+1));
         int build_number;
         if (android::base::ParseInt(num_string.c_str(), &build_number, 0)) {
             return build_number;
         }
     }

     LOG(ERROR) << "Failed to parse build number in " << str;
     return -1;
 }

 bool read_metadata_from_package(ZipArchiveHandle zip, std::string* meta_data) {
     ZipString metadata_path(METADATA_PATH);
     ZipEntry meta_entry;
     if (meta_data == nullptr) {
         LOG(ERROR) << "string* meta_data can't be nullptr";
         return false;
     }
     if (FindEntry(zip, metadata_path, &meta_entry) != 0) {
         LOG(ERROR) << "Failed to find " << METADATA_PATH << " in update package";
         return false;
     }

     meta_data->resize(meta_entry.uncompressed_length, '\0');
     if (ExtractToMemory(zip, &meta_entry, reinterpret_cast<uint8_t*>(&(*meta_data)[0]),
                         meta_entry.uncompressed_length) != 0) {
         LOG(ERROR) << "Failed to read metadata in update package";
         return false;
     }
     return true;
 }

 // Read the build.version.incremental of src/tgt from the metadata and log it to last_install.
 static void read_source_target_build(ZipArchiveHandle zip, std::vector<std::string>& log_buffer) {
     std::string meta_data;
     if (!read_metadata_from_package(zip, &meta_data)) {
         return;
     }
     // Examples of the pre-build and post-build strings in metadata:
     // pre-build-incremental=2943039
     // post-build-incremental=2951741
     std::vector<std::string> lines = android::base::Split(meta_data, "\n");
     for (const std::string& line : lines) {
         std::string str = android::base::Trim(line);
         if (android::base::StartsWith(str, "pre-build-incremental")){
             int source_build = parse_build_number(str);
             if (source_build != -1) {
                 log_buffer.push_back(android::base::StringPrintf("source_build: %d",
                         source_build));
             }
         } else if (android::base::StartsWith(str, "post-build-incremental")) {
             int target_build = parse_build_number(str);
             if (target_build != -1) {
                 log_buffer.push_back(android::base::StringPrintf("target_build: %d",
                         target_build));
             }
         }
     }
 }

 // Extract the update binary from the open zip archive |zip| located at |path|
 // and store into |cmd| the command line that should be called. The |status_fd|
 // is the file descriptor the child process should use to report back the
 // progress of the update.
 static int
 update_binary_command(const char* path, ZipArchiveHandle zip, int retry_count,
                       int status_fd, std::vector<std::string>* cmd);

 #ifdef AB_OTA_UPDATER

 // Parses the metadata of the OTA package in |zip| and checks whether we are
 // allowed to accept this A/B package. Downgrading is not allowed unless
 // explicitly enabled in the package and only for incremental packages.
 static int check_newer_ab_build(ZipArchiveHandle zip) {
   std::string metadata_str;
   if (!read_metadata_from_package(zip, &metadata_str)) {
     return INSTALL_CORRUPT;
   }
   std::map<std::string, std::string> metadata;
   for (const std::string& line : android::base::Split(metadata_str, "\n")) {
     size_t eq = line.find('=');
     if (eq != std::string::npos) {
       metadata[line.substr(0, eq)] = line.substr(eq + 1);
     }
   }

   std::string value = android::base::GetProperty("ro.product.device", "");
   const std::string& pkg_device = metadata["pre-device"];
   if (pkg_device != value || pkg_device.empty()) {
     LOG(ERROR) << "Package is for product " << pkg_device << " but expected " << value;
     return INSTALL_ERROR;
   }

   // We allow the package to not have any serialno, but if it has a non-empty
   // value it should match.
   value = android::base::GetProperty("ro.serialno", "");
   const std::string& pkg_serial_no = metadata["serialno"];
   if (!pkg_serial_no.empty() && pkg_serial_no != value) {
     LOG(ERROR) << "Package is for serial " << pkg_serial_no;
     return INSTALL_ERROR;
   }

   if (metadata["ota-type"] != "AB") {
     LOG(ERROR) << "Package is not A/B";
     return INSTALL_ERROR;
   }

   // Incremental updates should match the current build.
   value = android::base::GetProperty("ro.build.version.incremental", "");
   const std::string& pkg_pre_build = metadata["pre-build-incremental"];
   if (!pkg_pre_build.empty() && pkg_pre_build != value) {
     LOG(ERROR) << "Package is for source build " << pkg_pre_build << " but expected " << value;
     return INSTALL_ERROR;
   }

   value = android::base::GetProperty("ro.build.fingerprint", "");
   const std::string& pkg_pre_build_fingerprint = metadata["pre-build"];
   if (!pkg_pre_build_fingerprint.empty() && pkg_pre_build_fingerprint != value) {
     LOG(ERROR) << "Package is for source build " << pkg_pre_build_fingerprint << " but expected "
                << value;
     return INSTALL_ERROR;
   }

   // Check for downgrade version.
   int64_t build_timestamp =
       android::base::GetIntProperty("ro.build.date.utc", std::numeric_limits<int64_t>::max());
   int64_t pkg_post_timestamp = 0;
   // We allow to full update to the same version we are running, in case there
   // is a problem with the current copy of that version.
   if (metadata["post-timestamp"].empty() ||
       !android::base::ParseInt(metadata["post-timestamp"].c_str(), &pkg_post_timestamp) ||
       pkg_post_timestamp < build_timestamp) {
     if (metadata["ota-downgrade"] != "yes") {
       LOG(ERROR) << "Update package is older than the current build, expected a build "
                     "newer than timestamp "
                  << build_timestamp << " but package has timestamp " << pkg_post_timestamp
                  << " and downgrade not allowed.";
       return INSTALL_ERROR;
     }
     if (pkg_pre_build_fingerprint.empty()) {
       LOG(ERROR) << "Downgrade package must have a pre-build version set, not allowed.";
       return INSTALL_ERROR;
     }
   }

   return 0;
 }

 static int
 update_binary_command(const char* path, ZipArchiveHandle zip, int retry_count,
                       int status_fd, std::vector<std::string>* cmd)
 {
     int ret = check_newer_ab_build(zip);
     if (ret) {
         return ret;
     }

     // For A/B updates we extract the payload properties to a buffer and obtain
     // the RAW payload offset in the zip file.
     ZipString property_name(AB_OTA_PAYLOAD_PROPERTIES);
     ZipEntry properties_entry;
     if (FindEntry(zip, property_name, &properties_entry) != 0) {
         LOG(ERROR) << "Can't find " << AB_OTA_PAYLOAD_PROPERTIES;
         return INSTALL_CORRUPT;
     }
     std::vector<uint8_t> payload_properties(
             properties_entry.uncompressed_length);
     if (ExtractToMemory(zip, &properties_entry, payload_properties.data(),
                         properties_entry.uncompressed_length) != 0) {
         LOG(ERROR) << "Can't extract " << AB_OTA_PAYLOAD_PROPERTIES;
         return INSTALL_CORRUPT;
     }

     ZipString payload_name(AB_OTA_PAYLOAD);
     ZipEntry payload_entry;
     if (FindEntry(zip, payload_name, &payload_entry) != 0) {
         LOG(ERROR) << "Can't find " << AB_OTA_PAYLOAD;
         return INSTALL_CORRUPT;
     }
     long payload_offset = payload_entry.offset;
     *cmd = {
         "/sbin/update_engine_sideload",
         android::base::StringPrintf("--payload=file://%s", path),
         android::base::StringPrintf("--offset=%ld", payload_offset),
         "--headers=" + std::string(payload_properties.begin(),
                                    payload_properties.end()),
         android::base::StringPrintf("--status_fd=%d", status_fd),
     };
     return 0;
 }

 #else  // !AB_OTA_UPDATER

 static int
 update_binary_command(const char* path, ZipArchiveHandle zip, int retry_count,
                       int status_fd, std::vector<std::string>* cmd)
 {
     // On traditional updates we extract the update binary from the package.
     ZipString binary_name(ASSUMED_UPDATE_BINARY_NAME);
     ZipEntry binary_entry;
     if (FindEntry(zip, binary_name, &binary_entry) != 0) {
         return INSTALL_CORRUPT;
     }

     const char* binary = "/tmp/update_binary";
     unlink(binary);
     int fd = creat(binary, 0755);
     if (fd < 0) {
         PLOG(ERROR) << "Can't make " << binary;
         return INSTALL_ERROR;
     }
     int error = ExtractEntryToFile(zip, &binary_entry, fd);
     close(fd);

     if (error != 0) {
         LOG(ERROR) << "Can't copy " << ASSUMED_UPDATE_BINARY_NAME
                    << " : " << ErrorCodeString(error);
         return INSTALL_ERROR;
     }

     *cmd = {
         binary,
         EXPAND(RECOVERY_API_VERSION),   // defined in Android.mk
         std::to_string(status_fd),
         path,
     };
     if (retry_count > 0)
         cmd->push_back("retry");
     return 0;
 }
 #endif  // !AB_OTA_UPDATER

 // If the package contains an update binary, extract it and run it.
 static int try_update_binary(const char* path, ZipArchiveHandle zip, bool* wipe_cache,
                              std::vector<std::string>& log_buffer, int retry_count) {
   read_source_target_build(zip, log_buffer);

   int pipefd[2];
   pipe(pipefd);

   std::vector<std::string> args;
   int ret = update_binary_command(path, zip, retry_count, pipefd[1], &args);
   if (ret) {
     close(pipefd[0]);
     close(pipefd[1]);
     return ret;
   }

   // When executing the update binary contained in the package, the
   // arguments passed are:
   //
   //   - the version number for this interface
   //
   //   - an FD to which the program can write in order to update the
   //     progress bar.  The program can write single-line commands:
   //
   //        progress <frac> <secs>
   //            fill up the next <frac> part of of the progress bar
   //            over <secs> seconds.  If <secs> is zero, use
   //            set_progress commands to manually control the
   //            progress of this segment of the bar.
   //
   //        set_progress <frac>
   //            <frac> should be between 0.0 and 1.0; sets the
   //            progress bar within the segment defined by the most
   //            recent progress command.
   //
   //        ui_print <string>
   //            display <string> on the screen.
   //
   //        wipe_cache
   //            a wipe of cache will be performed following a successful
   //            installation.
   //
   //        clear_display
   //            turn off the text display.
   //
   //        enable_reboot
   //            packages can explicitly request that they want the user
   //            to be able to reboot during installation (useful for
   //            debugging packages that don't exit).
   //
   //        retry_update
   //            updater encounters some issue during the update. It requests
   //            a reboot to retry the same package automatically.
   //
   //        log <string>
   //            updater requests logging the string (e.g. cause of the
   //            failure).
   //
   //   - the name of the package zip file.
   //
   //   - an optional argument "retry" if this update is a retry of a failed
   //   update attempt.
   //

   // Convert the vector to a NULL-terminated char* array suitable for execv.
   const char* chr_args[args.size() + 1];
   chr_args[args.size()] = nullptr;
   for (size_t i = 0; i < args.size(); i++) {
     chr_args[i] = args[i].c_str();
   }

   pid_t pid = fork();

   if (pid == -1) {
     close(pipefd[0]);
     close(pipefd[1]);
     PLOG(ERROR) << "Failed to fork update binary";
     return INSTALL_ERROR;
   }

   if (pid == 0) {
     umask(022);
     close(pipefd[0]);
     execv(chr_args[0], const_cast<char**>(chr_args));
     PLOG(ERROR) << "Can't run " << chr_args[0];
     _exit(-1);
   }
   close(pipefd[1]);

   *wipe_cache = false;
   bool retry_update = false;

   char buffer[1024];
   FILE* from_child = fdopen(pipefd[0], "r");
   while (fgets(buffer, sizeof(buffer), from_child) != nullptr) {
     std::string line(buffer);
     size_t space = line.find_first_of(" \n");
     std::string command(line.substr(0, space));
     if (command.empty()) continue;

     // Get rid of the leading and trailing space and/or newline.
     std::string args = space == std::string::npos ? "" : android::base::Trim(line.substr(space));

     if (command == "progress") {
       std::vector<std::string> tokens = android::base::Split(args, " ");
       double fraction;
       int seconds;
       if (tokens.size() == 2 && android::base::ParseDouble(tokens[0].c_str(), &fraction) &&
           android::base::ParseInt(tokens[1], &seconds)) {
         ui->ShowProgress(fraction * (1 - VERIFICATION_PROGRESS_FRACTION), seconds);
       } else {
         LOG(ERROR) << "invalid \"progress\" parameters: " << line;
       }
     } else if (command == "set_progress") {
       std::vector<std::string> tokens = android::base::Split(args, " ");
       double fraction;
       if (tokens.size() == 1 && android::base::ParseDouble(tokens[0].c_str(), &fraction)) {
         ui->SetProgress(fraction);
       } else {
         LOG(ERROR) << "invalid \"set_progress\" parameters: " << line;
       }
     } else if (command == "ui_print") {
       ui->PrintOnScreenOnly("%s\n", args.c_str());
       fflush(stdout);
     } else if (command == "wipe_cache") {
       *wipe_cache = true;
     } else if (command == "clear_display") {
       ui->SetBackground(RecoveryUI::NONE);
     } else if (command == "enable_reboot") {
       // packages can explicitly request that they want the user
       // to be able to reboot during installation (useful for
       // debugging packages that don't exit).
       ui->SetEnableReboot(true);
     } else if (command == "retry_update") {
       retry_update = true;
     } else if (command == "log") {
       if (!args.empty()) {
         // Save the logging request from updater and write to last_install later.
         log_buffer.push_back(args);
       } else {
         LOG(ERROR) << "invalid \"log\" parameters: " << line;
       }
     } else {
       LOG(ERROR) << "unknown command [" << command << "]";
     }
   }
   fclose(from_child);

   int status;
   waitpid(pid, &status, 0);
   if (retry_update) {
     return INSTALL_RETRY;
   }
   if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
     LOG(ERROR) << "Error in " << path << " (Status " << WEXITSTATUS(status) << ")";
     return INSTALL_ERROR;
   }

   return INSTALL_SUCCESS;
 }

 static int
 really_install_package(const char *path, bool* wipe_cache, bool needs_mount,
                        std::vector<std::string>& log_buffer, int retry_count)
 {
     ui->SetBackground(RecoveryUI::INSTALLING_UPDATE);
     ui->Print("Finding update package...\n");
     // Give verification half the progress bar...
     ui->SetProgressType(RecoveryUI::DETERMINATE);
     ui->ShowProgress(VERIFICATION_PROGRESS_FRACTION, VERIFICATION_PROGRESS_TIME);
     LOG(INFO) << "Update location: " << path;

     // Map the update package into memory.
     ui->Print("Opening update package...\n");

     if (path && needs_mount) {
         if (path[0] == '@') {
             ensure_path_mounted(path+1);
         } else {
             ensure_path_mounted(path);
         }
     }

     MemMapping map;
     if (sysMapFile(path, &map) != 0) {
         LOG(ERROR) << "failed to map file";
         return INSTALL_CORRUPT;
     }

     // Verify package.
     if (!verify_package(map.addr, map.length)) {
         log_buffer.push_back(android::base::StringPrintf("error: %d", kZipVerificationFailure));
         sysReleaseMap(&map);
         return INSTALL_CORRUPT;
     }

     // Try to open the package.
     ZipArchiveHandle zip;
     int err = OpenArchiveFromMemory(map.addr, map.length, path, &zip);
     if (err != 0) {
         LOG(ERROR) << "Can't open " << path << " : " << ErrorCodeString(err);
         log_buffer.push_back(android::base::StringPrintf("error: %d", kZipOpenFailure));

         sysReleaseMap(&map);
         CloseArchive(zip);
         return INSTALL_CORRUPT;
     }

     // Verify and install the contents of the package.
     ui->Print("Installing update...\n");
     if (retry_count > 0) {
         ui->Print("Retry attempt: %d\n", retry_count);
     }
     ui->SetEnableReboot(false);
     int result = try_update_binary(path, zip, wipe_cache, log_buffer, retry_count);
     ui->SetEnableReboot(true);
     ui->Print("\n");

     sysReleaseMap(&map);
     CloseArchive(zip);
     return result;
 }

 int
 install_package(const char* path, bool* wipe_cache, const char* install_file,
                 bool needs_mount, int retry_count)
 {
     modified_flash = true;
     auto start = std::chrono::system_clock::now();

     int result;
     std::vector<std::string> log_buffer;
     if (setup_install_mounts() != 0) {
         LOG(ERROR) << "failed to set up expected mounts for install; aborting";
         result = INSTALL_ERROR;
     } else {
         result = really_install_package(path, wipe_cache, needs_mount, log_buffer, retry_count);
     }

     // Measure the time spent to apply OTA update in seconds.
     std::chrono::duration<double> duration = std::chrono::system_clock::now() - start;
     int time_total = static_cast<int>(duration.count());

     if (ensure_path_mounted(UNCRYPT_STATUS) != 0) {
         LOG(WARNING) << "Can't mount " << UNCRYPT_STATUS;
     } else {
         std::string uncrypt_status;
         if (!android::base::ReadFileToString(UNCRYPT_STATUS, &uncrypt_status)) {
             PLOG(WARNING) << "failed to read uncrypt status";
         } else if (!android::base::StartsWith(uncrypt_status, "uncrypt_")) {
             PLOG(WARNING) << "corrupted uncrypt_status: " << uncrypt_status;
         } else {
             log_buffer.push_back(android::base::Trim(uncrypt_status));
         }
     }

     // The first two lines need to be the package name and install result.
     std::vector<std::string> log_header = {
         path,
         result == INSTALL_SUCCESS ? "1" : "0",
         "time_total: " + std::to_string(time_total),
         "retry: " + std::to_string(retry_count),
     };
     std::string log_content = android::base::Join(log_header, "\n") + "\n" +
             android::base::Join(log_buffer, "\n");
     if (!android::base::WriteStringToFile(log_content, install_file)) {
         PLOG(ERROR) << "failed to write " << install_file;
     }

     // Write a copy into last_log.
     LOG(INFO) << log_content;

     return result;
 }

 bool verify_package(const unsigned char* package_data, size_t package_size) {
     std::vector<Certificate> loadedKeys;
     if (!load_keys(PUBLIC_KEYS_FILE, loadedKeys)) {
         LOG(ERROR) << "Failed to load keys";
         return false;
     }
     LOG(INFO) << loadedKeys.size() << " key(s) loaded from " << PUBLIC_KEYS_FILE;

     // Verify package.
     ui->Print("Verifying update package...\n");
     auto t0 = std::chrono::system_clock::now();
     int err = verify_file(const_cast<unsigned char*>(package_data), package_size, loadedKeys);
     std::chrono::duration<double> duration = std::chrono::system_clock::now() - t0;
     ui->Print("Update package verification took %.1f s (result %d).\n", duration.count(), err);
     if (err != VERIFY_SUCCESS) {
         LOG(ERROR) << "Signature verification failed";
         LOG(ERROR) << "error: " << kZipVerificationFailure;
         return false;
     }
     return true;
 }
	/*
	* Copyright (C) 2007 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "install.h"

	#include <ctype.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <inttypes.h>
	#include <limits.h>
	#include <string.h>
	#include <sys/stat.h>
	#include <sys/wait.h>
	#include <unistd.h>

	#include <chrono>
	#include <limits>
	#include <map>
	#include <string>
	#include <vector>

	#include <android-base/file.h>
	#include <android-base/logging.h>
	#include <android-base/parsedouble.h>
	#include <android-base/parseint.h>
	#include <android-base/properties.h>
	#include <android-base/stringprintf.h>
	#include <android-base/strings.h>
	#include <ziparchive/zip_archive.h>

	#include "common.h"
	#include "error_code.h"
	#include "minui/minui.h"
	#include "otautil/SysUtil.h"
	#include "roots.h"
	#include "ui.h"
	#include "verifier.h"

	#define ASSUMED_UPDATE_BINARY_NAME "META-INF/com/google/android/update-binary"
	static constexpr const char* AB_OTA_PAYLOAD_PROPERTIES = "payload_properties.txt";
	static constexpr const char* AB_OTA_PAYLOAD = "payload.bin";
	#define PUBLIC_KEYS_FILE "/res/keys"
	static constexpr const char* METADATA_PATH = "META-INF/com/android/metadata";
	static constexpr const char* UNCRYPT_STATUS = "/cache/recovery/uncrypt_status";

	// Default allocation of progress bar segments to operations
	static constexpr int VERIFICATION_PROGRESS_TIME = 60;
	static constexpr float VERIFICATION_PROGRESS_FRACTION = 0.25;
	static constexpr float DEFAULT_FILES_PROGRESS_FRACTION = 0.4;
	static constexpr float DEFAULT_IMAGE_PROGRESS_FRACTION = 0.1;

	// This function parses and returns the build.version.incremental
	static int parse_build_number(const std::string& str) {
	size_t pos = str.find('=');
	if (pos != std::string::npos) {
	std::string num_string = android::base::Trim(str.substr(pos+1));
	int build_number;
	if (android::base::ParseInt(num_string.c_str(), &build_number, 0)) {
	return build_number;
	}
	}

	LOG(ERROR) << "Failed to parse build number in " << str;
	return -1;
	}

	bool read_metadata_from_package(ZipArchiveHandle zip, std::string* meta_data) {
	ZipString metadata_path(METADATA_PATH);
	ZipEntry meta_entry;
	if (meta_data == nullptr) {
	LOG(ERROR) << "string* meta_data can't be nullptr";
	return false;
	}
	if (FindEntry(zip, metadata_path, &meta_entry) != 0) {
	LOG(ERROR) << "Failed to find " << METADATA_PATH << " in update package";
	return false;
	}

	meta_data->resize(meta_entry.uncompressed_length, '\0');
	if (ExtractToMemory(zip, &meta_entry, reinterpret_cast<uint8_t>(&(meta_data)[0]),
	meta_entry.uncompressed_length) != 0) {
	LOG(ERROR) << "Failed to read metadata in update package";
	return false;
	}
	return true;
	}

	// Read the build.version.incremental of src/tgt from the metadata and log it to last_install.
	static void read_source_target_build(ZipArchiveHandle zip, std::vector<std::string>& log_buffer) {
	std::string meta_data;
	if (!read_metadata_from_package(zip, &meta_data)) {
	return;
	}
	// Examples of the pre-build and post-build strings in metadata:
	// pre-build-incremental=2943039
	// post-build-incremental=2951741
	std::vector<std::string> lines = android::base::Split(meta_data, "\n");
	for (const std::string& line : lines) {
	std::string str = android::base::Trim(line);
	if (android::base::StartsWith(str, "pre-build-incremental")){
	int source_build = parse_build_number(str);
	if (source_build != -1) {
	log_buffer.push_back(android::base::StringPrintf("source_build: %d",
	source_build));
	}
	} else if (android::base::StartsWith(str, "post-build-incremental")) {
	int target_build = parse_build_number(str);
	if (target_build != -1) {
	log_buffer.push_back(android::base::StringPrintf("target_build: %d",
	target_build));
	}
	}
	}
	}

	// Extract the update binary from the open zip archive \|zip\| located at \|path\|
	// and store into \|cmd\| the command line that should be called. The \|status_fd\|
	// is the file descriptor the child process should use to report back the
	// progress of the update.
	static int
	update_binary_command(const char* path, ZipArchiveHandle zip, int retry_count,
	int status_fd, std::vector<std::string>* cmd);

	#ifdef AB_OTA_UPDATER

	// Parses the metadata of the OTA package in \|zip\| and checks whether we are
	// allowed to accept this A/B package. Downgrading is not allowed unless
	// explicitly enabled in the package and only for incremental packages.
	static int check_newer_ab_build(ZipArchiveHandle zip) {
	std::string metadata_str;
	if (!read_metadata_from_package(zip, &metadata_str)) {
	return INSTALL_CORRUPT;
	}
	std::map<std::string, std::string> metadata;
	for (const std::string& line : android::base::Split(metadata_str, "\n")) {
	size_t eq = line.find('=');
	if (eq != std::string::npos) {
	metadata[line.substr(0, eq)] = line.substr(eq + 1);
	}
	}

	std::string value = android::base::GetProperty("ro.product.device", "");
	const std::string& pkg_device = metadata["pre-device"];
	if (pkg_device != value \|\| pkg_device.empty()) {
	LOG(ERROR) << "Package is for product " << pkg_device << " but expected " << value;
	return INSTALL_ERROR;
	}

	// We allow the package to not have any serialno, but if it has a non-empty
	// value it should match.
	value = android::base::GetProperty("ro.serialno", "");
	const std::string& pkg_serial_no = metadata["serialno"];
	if (!pkg_serial_no.empty() && pkg_serial_no != value) {
	LOG(ERROR) << "Package is for serial " << pkg_serial_no;
	return INSTALL_ERROR;
	}

	if (metadata["ota-type"] != "AB") {
	LOG(ERROR) << "Package is not A/B";
	return INSTALL_ERROR;
	}

	// Incremental updates should match the current build.
	value = android::base::GetProperty("ro.build.version.incremental", "");
	const std::string& pkg_pre_build = metadata["pre-build-incremental"];
	if (!pkg_pre_build.empty() && pkg_pre_build != value) {
	LOG(ERROR) << "Package is for source build " << pkg_pre_build << " but expected " << value;
	return INSTALL_ERROR;
	}

	value = android::base::GetProperty("ro.build.fingerprint", "");
	const std::string& pkg_pre_build_fingerprint = metadata["pre-build"];
	if (!pkg_pre_build_fingerprint.empty() && pkg_pre_build_fingerprint != value) {
	LOG(ERROR) << "Package is for source build " << pkg_pre_build_fingerprint << " but expected "
	<< value;
	return INSTALL_ERROR;
	}

	// Check for downgrade version.
	int64_t build_timestamp =
	android::base::GetIntProperty("ro.build.date.utc", std::numeric_limits<int64_t>::max());
	int64_t pkg_post_timestamp = 0;
	// We allow to full update to the same version we are running, in case there
	// is a problem with the current copy of that version.
	if (metadata["post-timestamp"].empty() \|\|
	!android::base::ParseInt(metadata["post-timestamp"].c_str(), &pkg_post_timestamp) \|\|
	pkg_post_timestamp < build_timestamp) {
	if (metadata["ota-downgrade"] != "yes") {
	LOG(ERROR) << "Update package is older than the current build, expected a build "
	"newer than timestamp "
	<< build_timestamp << " but package has timestamp " << pkg_post_timestamp
	<< " and downgrade not allowed.";
	return INSTALL_ERROR;
	}
	if (pkg_pre_build_fingerprint.empty()) {
	LOG(ERROR) << "Downgrade package must have a pre-build version set, not allowed.";
	return INSTALL_ERROR;
	}
	}

	return 0;
	}

	static int
	update_binary_command(const char* path, ZipArchiveHandle zip, int retry_count,
	int status_fd, std::vector<std::string>* cmd)
	{
	int ret = check_newer_ab_build(zip);
	if (ret) {
	return ret;
	}

	// For A/B updates we extract the payload properties to a buffer and obtain
	// the RAW payload offset in the zip file.
	ZipString property_name(AB_OTA_PAYLOAD_PROPERTIES);
	ZipEntry properties_entry;
	if (FindEntry(zip, property_name, &properties_entry) != 0) {
	LOG(ERROR) << "Can't find " << AB_OTA_PAYLOAD_PROPERTIES;
	return INSTALL_CORRUPT;
	}
	std::vector<uint8_t> payload_properties(
	properties_entry.uncompressed_length);
	if (ExtractToMemory(zip, &properties_entry, payload_properties.data(),
	properties_entry.uncompressed_length) != 0) {
	LOG(ERROR) << "Can't extract " << AB_OTA_PAYLOAD_PROPERTIES;
	return INSTALL_CORRUPT;
	}

	ZipString payload_name(AB_OTA_PAYLOAD);
	ZipEntry payload_entry;
	if (FindEntry(zip, payload_name, &payload_entry) != 0) {
	LOG(ERROR) << "Can't find " << AB_OTA_PAYLOAD;
	return INSTALL_CORRUPT;
	}
	long payload_offset = payload_entry.offset;
	*cmd = {
	"/sbin/update_engine_sideload",
	android::base::StringPrintf("--payload=file://%s", path),
	android::base::StringPrintf("--offset=%ld", payload_offset),
	"--headers=" + std::string(payload_properties.begin(),
	payload_properties.end()),
	android::base::StringPrintf("--status_fd=%d", status_fd),
	};
	return 0;
	}

	#else // !AB_OTA_UPDATER

	static int
	update_binary_command(const char* path, ZipArchiveHandle zip, int retry_count,
	int status_fd, std::vector<std::string>* cmd)
	{
	// On traditional updates we extract the update binary from the package.
	ZipString binary_name(ASSUMED_UPDATE_BINARY_NAME);
	ZipEntry binary_entry;
	if (FindEntry(zip, binary_name, &binary_entry) != 0) {
	return INSTALL_CORRUPT;
	}

	const char* binary = "/tmp/update_binary";
	unlink(binary);
	int fd = creat(binary, 0755);
	if (fd < 0) {
	PLOG(ERROR) << "Can't make " << binary;
	return INSTALL_ERROR;
	}
	int error = ExtractEntryToFile(zip, &binary_entry, fd);
	close(fd);

	if (error != 0) {
	LOG(ERROR) << "Can't copy " << ASSUMED_UPDATE_BINARY_NAME
	<< " : " << ErrorCodeString(error);
	return INSTALL_ERROR;
	}

	*cmd = {
	binary,
	EXPAND(RECOVERY_API_VERSION), // defined in Android.mk
	std::to_string(status_fd),
	path,
	};
	if (retry_count > 0)
	cmd->push_back("retry");
	return 0;
	}
	#endif // !AB_OTA_UPDATER

	// If the package contains an update binary, extract it and run it.
	static int try_update_binary(const char* path, ZipArchiveHandle zip, bool* wipe_cache,
	std::vector<std::string>& log_buffer, int retry_count) {
	read_source_target_build(zip, log_buffer);

	int pipefd[2];
	pipe(pipefd);

	std::vector<std::string> args;
	int ret = update_binary_command(path, zip, retry_count, pipefd[1], &args);
	if (ret) {
	close(pipefd[0]);
	close(pipefd[1]);
	return ret;
	}

	// When executing the update binary contained in the package, the
	// arguments passed are:
	//
	// - the version number for this interface
	//
	// - an FD to which the program can write in order to update the
	// progress bar. The program can write single-line commands:
	//
	// progress <frac> <secs>
	// fill up the next <frac> part of of the progress bar
	// over <secs> seconds. If <secs> is zero, use
	// set_progress commands to manually control the
	// progress of this segment of the bar.
	//
	// set_progress <frac>
	// <frac> should be between 0.0 and 1.0; sets the
	// progress bar within the segment defined by the most
	// recent progress command.
	//
	// ui_print <string>
	// display <string> on the screen.
	//
	// wipe_cache
	// a wipe of cache will be performed following a successful
	// installation.
	//
	// clear_display
	// turn off the text display.
	//
	// enable_reboot
	// packages can explicitly request that they want the user
	// to be able to reboot during installation (useful for
	// debugging packages that don't exit).
	//
	// retry_update
	// updater encounters some issue during the update. It requests
	// a reboot to retry the same package automatically.
	//
	// log <string>
	// updater requests logging the string (e.g. cause of the
	// failure).
	//
	// - the name of the package zip file.
	//
	// - an optional argument "retry" if this update is a retry of a failed
	// update attempt.
	//

	// Convert the vector to a NULL-terminated char* array suitable for execv.
	const char* chr_args[args.size() + 1];
	chr_args[args.size()] = nullptr;
	for (size_t i = 0; i < args.size(); i++) {
	chr_args[i] = args[i].c_str();
	}

	pid_t pid = fork();

	if (pid == -1) {
	close(pipefd[0]);
	close(pipefd[1]);
	PLOG(ERROR) << "Failed to fork update binary";
	return INSTALL_ERROR;
	}

	if (pid == 0) {
	umask(022);
	close(pipefd[0]);
	execv(chr_args[0], const_cast<char**>(chr_args));
	PLOG(ERROR) << "Can't run " << chr_args[0];
	_exit(-1);
	}
	close(pipefd[1]);

	*wipe_cache = false;
	bool retry_update = false;

	char buffer[1024];
	FILE* from_child = fdopen(pipefd[0], "r");
	while (fgets(buffer, sizeof(buffer), from_child) != nullptr) {
	std::string line(buffer);
	size_t space = line.find_first_of(" \n");
	std::string command(line.substr(0, space));
	if (command.empty()) continue;

	// Get rid of the leading and trailing space and/or newline.
	std::string args = space == std::string::npos ? "" : android::base::Trim(line.substr(space));

	if (command == "progress") {
	std::vector<std::string> tokens = android::base::Split(args, " ");
	double fraction;
	int seconds;
	if (tokens.size() == 2 && android::base::ParseDouble(tokens[0].c_str(), &fraction) &&
	android::base::ParseInt(tokens[1], &seconds)) {
	ui->ShowProgress(fraction * (1 - VERIFICATION_PROGRESS_FRACTION), seconds);
	} else {
	LOG(ERROR) << "invalid \"progress\" parameters: " << line;
	}
	} else if (command == "set_progress") {
	std::vector<std::string> tokens = android::base::Split(args, " ");
	double fraction;
	if (tokens.size() == 1 && android::base::ParseDouble(tokens[0].c_str(), &fraction)) {
	ui->SetProgress(fraction);
	} else {
	LOG(ERROR) << "invalid \"set_progress\" parameters: " << line;
	}
	} else if (command == "ui_print") {
	ui->PrintOnScreenOnly("%s\n", args.c_str());
	fflush(stdout);
	} else if (command == "wipe_cache") {
	*wipe_cache = true;
	} else if (command == "clear_display") {
	ui->SetBackground(RecoveryUI::NONE);
	} else if (command == "enable_reboot") {
	// packages can explicitly request that they want the user
	// to be able to reboot during installation (useful for
	// debugging packages that don't exit).
	ui->SetEnableReboot(true);
	} else if (command == "retry_update") {
	retry_update = true;
	} else if (command == "log") {
	if (!args.empty()) {
	// Save the logging request from updater and write to last_install later.
	log_buffer.push_back(args);
	} else {
	LOG(ERROR) << "invalid \"log\" parameters: " << line;
	}
	} else {
	LOG(ERROR) << "unknown command [" << command << "]";
	}
	}
	fclose(from_child);

	int status;
	waitpid(pid, &status, 0);
	if (retry_update) {
	return INSTALL_RETRY;
	}
	if (!WIFEXITED(status) \|\| WEXITSTATUS(status) != 0) {
	LOG(ERROR) << "Error in " << path << " (Status " << WEXITSTATUS(status) << ")";
	return INSTALL_ERROR;
	}

	return INSTALL_SUCCESS;
	}

	static int
	really_install_package(const char path, bool wipe_cache, bool needs_mount,
	std::vector<std::string>& log_buffer, int retry_count)
	{
	ui->SetBackground(RecoveryUI::INSTALLING_UPDATE);
	ui->Print("Finding update package...\n");
	// Give verification half the progress bar...
	ui->SetProgressType(RecoveryUI::DETERMINATE);
	ui->ShowProgress(VERIFICATION_PROGRESS_FRACTION, VERIFICATION_PROGRESS_TIME);
	LOG(INFO) << "Update location: " << path;

	// Map the update package into memory.
	ui->Print("Opening update package...\n");

	if (path && needs_mount) {
	if (path[0] == '@') {
	ensure_path_mounted(path+1);
	} else {
	ensure_path_mounted(path);
	}
	}

	MemMapping map;
	if (sysMapFile(path, &map) != 0) {
	LOG(ERROR) << "failed to map file";
	return INSTALL_CORRUPT;
	}

	// Verify package.
	if (!verify_package(map.addr, map.length)) {
	log_buffer.push_back(android::base::StringPrintf("error: %d", kZipVerificationFailure));
	sysReleaseMap(&map);
	return INSTALL_CORRUPT;
	}

	// Try to open the package.
	ZipArchiveHandle zip;
	int err = OpenArchiveFromMemory(map.addr, map.length, path, &zip);
	if (err != 0) {
	LOG(ERROR) << "Can't open " << path << " : " << ErrorCodeString(err);
	log_buffer.push_back(android::base::StringPrintf("error: %d", kZipOpenFailure));

	sysReleaseMap(&map);
	CloseArchive(zip);
	return INSTALL_CORRUPT;
	}

	// Verify and install the contents of the package.
	ui->Print("Installing update...\n");
	if (retry_count > 0) {
	ui->Print("Retry attempt: %d\n", retry_count);
	}
	ui->SetEnableReboot(false);
	int result = try_update_binary(path, zip, wipe_cache, log_buffer, retry_count);
	ui->SetEnableReboot(true);
	ui->Print("\n");

	sysReleaseMap(&map);
	CloseArchive(zip);
	return result;
	}

	int
	install_package(const char* path, bool* wipe_cache, const char* install_file,
	bool needs_mount, int retry_count)
	{
	modified_flash = true;
	auto start = std::chrono::system_clock::now();

	int result;
	std::vector<std::string> log_buffer;
	if (setup_install_mounts() != 0) {
	LOG(ERROR) << "failed to set up expected mounts for install; aborting";
	result = INSTALL_ERROR;
	} else {
	result = really_install_package(path, wipe_cache, needs_mount, log_buffer, retry_count);
	}

	// Measure the time spent to apply OTA update in seconds.
	std::chrono::duration<double> duration = std::chrono::system_clock::now() - start;
	int time_total = static_cast<int>(duration.count());

	if (ensure_path_mounted(UNCRYPT_STATUS) != 0) {
	LOG(WARNING) << "Can't mount " << UNCRYPT_STATUS;
	} else {
	std::string uncrypt_status;
	if (!android::base::ReadFileToString(UNCRYPT_STATUS, &uncrypt_status)) {
	PLOG(WARNING) << "failed to read uncrypt status";
	} else if (!android::base::StartsWith(uncrypt_status, "uncrypt_")) {
	PLOG(WARNING) << "corrupted uncrypt_status: " << uncrypt_status;
	} else {
	log_buffer.push_back(android::base::Trim(uncrypt_status));
	}
	}

	// The first two lines need to be the package name and install result.
	std::vector<std::string> log_header = {
	path,
	result == INSTALL_SUCCESS ? "1" : "0",
	"time_total: " + std::to_string(time_total),
	"retry: " + std::to_string(retry_count),
	};
	std::string log_content = android::base::Join(log_header, "\n") + "\n" +
	android::base::Join(log_buffer, "\n");
	if (!android::base::WriteStringToFile(log_content, install_file)) {
	PLOG(ERROR) << "failed to write " << install_file;
	}

	// Write a copy into last_log.
	LOG(INFO) << log_content;

	return result;
	}

	bool verify_package(const unsigned char* package_data, size_t package_size) {
	std::vector<Certificate> loadedKeys;
	if (!load_keys(PUBLIC_KEYS_FILE, loadedKeys)) {
	LOG(ERROR) << "Failed to load keys";
	return false;
	}
	LOG(INFO) << loadedKeys.size() << " key(s) loaded from " << PUBLIC_KEYS_FILE;

	// Verify package.
	ui->Print("Verifying update package...\n");
	auto t0 = std::chrono::system_clock::now();
	int err = verify_file(const_cast<unsigned char*>(package_data), package_size, loadedKeys);
	std::chrono::duration<double> duration = std::chrono::system_clock::now() - t0;
	ui->Print("Update package verification took %.1f s (result %d).\n", duration.count(), err);
	if (err != VERIFY_SUCCESS) {
	LOG(ERROR) << "Signature verification failed";
	LOG(ERROR) << "error: " << kZipVerificationFailure;
	return false;
	}
	return true;
	}