bootloader_message/bootloader_message.cpp - LeafOS-Project/android_bootable_recovery - Gitiles

 /*
  * Copyright (C) 2016 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 <bootloader_message/bootloader_message.h>

 #include <errno.h>
 #include <fcntl.h>
 #include <string.h>

 #include <optional>
 #include <string>
 #include <string_view>
 #include <vector>

 #include <android-base/file.h>
 #include <android-base/hex.h>
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/unique_fd.h>
 #include <fstab/fstab.h>

 #ifndef __ANDROID__
 #include <cutils/memory.h>  // for strlcpy
 #endif

 using android::fs_mgr::Fstab;
 using android::fs_mgr::ReadDefaultFstab;

 static std::optional<std::string> g_misc_device_for_test;

 // Exposed for test purpose.
 void SetMiscBlockDeviceForTest(std::string_view misc_device) {
   g_misc_device_for_test = misc_device;
 }

 std::string get_misc_blk_device(std::string* err) {
   if (g_misc_device_for_test.has_value() && !g_misc_device_for_test->empty()) {
     return *g_misc_device_for_test;
   }
   Fstab fstab;
   if (!ReadDefaultFstab(&fstab)) {
     *err = "failed to read default fstab";
     return "";
   }
   for (const auto& entry : fstab) {
     if (entry.mount_point == "/misc") {
       return entry.blk_device;
     }
   }

   *err = "failed to find /misc partition";
   return "";
 }

 // In recovery mode, recovery can get started and try to access the misc
 // device before the kernel has actually created it.
 static bool wait_for_device(const std::string& blk_device, std::string* err) {
   int tries = 0;
   int ret;
   err->clear();
   do {
     ++tries;
     struct stat buf;
     ret = stat(blk_device.c_str(), &buf);
     if (ret == -1) {
       *err += android::base::StringPrintf("failed to stat %s try %d: %s\n",
                                           blk_device.c_str(), tries, strerror(errno));
       sleep(1);
     }
   } while (ret && tries < 10);

   if (ret) {
     *err += android::base::StringPrintf("failed to stat %s\n", blk_device.c_str());
   }
   return ret == 0;
 }

 static bool read_misc_partition(void* p, size_t size, const std::string& misc_blk_device,
                                 size_t offset, std::string* err) {
   if (!wait_for_device(misc_blk_device, err)) {
     return false;
   }
   android::base::unique_fd fd(open(misc_blk_device.c_str(), O_RDONLY));
   if (fd == -1) {
     *err = android::base::StringPrintf("failed to open %s: %s", misc_blk_device.c_str(),
                                        strerror(errno));
     return false;
   }
   if (lseek(fd, static_cast<off_t>(offset), SEEK_SET) != static_cast<off_t>(offset)) {
     *err = android::base::StringPrintf("failed to lseek %s: %s", misc_blk_device.c_str(),
                                        strerror(errno));
     return false;
   }
   if (!android::base::ReadFully(fd, p, size)) {
     *err = android::base::StringPrintf("failed to read %s: %s", misc_blk_device.c_str(),
                                        strerror(errno));
     return false;
   }
   return true;
 }

 bool write_misc_partition(const void* p, size_t size, const std::string& misc_blk_device,
                           size_t offset, std::string* err) {
   android::base::unique_fd fd(open(misc_blk_device.c_str(), O_WRONLY));
   if (fd == -1) {
     *err = android::base::StringPrintf("failed to open %s: %s", misc_blk_device.c_str(),
                                        strerror(errno));
     return false;
   }
   if (lseek(fd, static_cast<off_t>(offset), SEEK_SET) != static_cast<off_t>(offset)) {
     *err = android::base::StringPrintf("failed to lseek %s: %s", misc_blk_device.c_str(),
                                        strerror(errno));
     return false;
   }
   if (!android::base::WriteFully(fd, p, size)) {
     *err = android::base::StringPrintf("failed to write %s: %s", misc_blk_device.c_str(),
                                        strerror(errno));
     return false;
   }
   if (fsync(fd) == -1) {
     *err = android::base::StringPrintf("failed to fsync %s: %s", misc_blk_device.c_str(),
                                        strerror(errno));
     return false;
   }
   return true;
 }

 std::string get_bootloader_message_blk_device(std::string* err) {
   std::string misc_blk_device = get_misc_blk_device(err);
   if (misc_blk_device.empty()) return "";
   if (!wait_for_device(misc_blk_device, err)) return "";
   return misc_blk_device;
 }

 bool read_bootloader_message_from(bootloader_message* boot, const std::string& misc_blk_device,
                                   std::string* err) {
   return read_misc_partition(boot, sizeof(*boot), misc_blk_device,
                              BOOTLOADER_MESSAGE_OFFSET_IN_MISC, err);
 }

 bool read_bootloader_message(bootloader_message* boot, std::string* err) {
   std::string misc_blk_device = get_misc_blk_device(err);
   if (misc_blk_device.empty()) {
     return false;
   }
   return read_bootloader_message_from(boot, misc_blk_device, err);
 }

 bool write_bootloader_message_to(const bootloader_message& boot, const std::string& misc_blk_device,
                                  std::string* err) {
   return write_misc_partition(&boot, sizeof(boot), misc_blk_device,
                               BOOTLOADER_MESSAGE_OFFSET_IN_MISC, err);
 }

 bool write_bootloader_message(const bootloader_message& boot, std::string* err) {
   std::string misc_blk_device = get_misc_blk_device(err);
   if (misc_blk_device.empty()) {
     return false;
   }
   return write_bootloader_message_to(boot, misc_blk_device, err);
 }

 bool clear_bootloader_message(std::string* err) {
   bootloader_message boot = {};
   return write_bootloader_message(boot, err);
 }

 bool write_bootloader_message(const std::vector<std::string>& options, std::string* err) {
   bootloader_message boot = {};
   update_bootloader_message_in_struct(&boot, options);

   return write_bootloader_message(boot, err);
 }

 bool write_bootloader_message_to(const std::vector<std::string>& options,
                                  const std::string& misc_blk_device, std::string* err) {
   bootloader_message boot = {};
   update_bootloader_message_in_struct(&boot, options);

   return write_bootloader_message_to(boot, misc_blk_device, err);
 }

 bool update_bootloader_message(const std::vector<std::string>& options, std::string* err) {
   bootloader_message boot;
   if (!read_bootloader_message(&boot, err)) {
     return false;
   }
   update_bootloader_message_in_struct(&boot, options);

   return write_bootloader_message(boot, err);
 }

 bool update_bootloader_message_in_struct(bootloader_message* boot,
                                          const std::vector<std::string>& options) {
   if (!boot) return false;
   // Replace the command & recovery fields.
   memset(boot->command, 0, sizeof(boot->command));
   memset(boot->recovery, 0, sizeof(boot->recovery));

   strlcpy(boot->command, "boot-recovery", sizeof(boot->command));

   std::string recovery = "recovery\n";
   for (const auto& s : options) {
     recovery += s;
     if (s.back() != '\n') {
       recovery += '\n';
     }
   }
   strlcpy(boot->recovery, recovery.c_str(), sizeof(boot->recovery));
   return true;
 }

 bool write_reboot_bootloader(std::string* err) {
   bootloader_message boot;
   if (!read_bootloader_message(&boot, err)) {
     return false;
   }
   if (boot.command[0] != '\0') {
     *err = "Bootloader command pending.";
     return false;
   }
   strlcpy(boot.command, "bootonce-bootloader", sizeof(boot.command));
   return write_bootloader_message(boot, err);
 }

 bool read_wipe_package(std::string* package_data, size_t size, std::string* err) {
   std::string misc_blk_device = get_misc_blk_device(err);
   if (misc_blk_device.empty()) {
     return false;
   }
   package_data->resize(size);
   return read_misc_partition(&(*package_data)[0], size, misc_blk_device,
                              WIPE_PACKAGE_OFFSET_IN_MISC, err);
 }

 bool write_wipe_package(const std::string& package_data, std::string* err) {
   std::string misc_blk_device = get_misc_blk_device(err);
   if (misc_blk_device.empty()) {
     return false;
   }
   static constexpr size_t kMaximumWipePackageSize =
       SYSTEM_SPACE_OFFSET_IN_MISC - WIPE_PACKAGE_OFFSET_IN_MISC;
   if (package_data.size() > kMaximumWipePackageSize) {
     *err = "Wipe package size " + std::to_string(package_data.size()) + " exceeds " +
            std::to_string(kMaximumWipePackageSize) + " bytes";
     return false;
   }
   return write_misc_partition(package_data.data(), package_data.size(), misc_blk_device,
                               WIPE_PACKAGE_OFFSET_IN_MISC, err);
 }

 static bool ValidateSystemSpaceRegion(size_t offset, size_t size, std::string* err) {
   if (size <= SYSTEM_SPACE_SIZE_IN_MISC && offset <= (SYSTEM_SPACE_SIZE_IN_MISC - size)) {
     return true;
   }
   *err = android::base::StringPrintf("Out of bound access (offset %zu size %zu)", offset, size);
   return false;
 }

 static bool ReadMiscPartitionSystemSpace(void* data, size_t size, size_t offset, std::string* err) {
   if (!ValidateSystemSpaceRegion(offset, size, err)) {
     return false;
   }
   auto misc_blk_device = get_misc_blk_device(err);
   if (misc_blk_device.empty()) {
     return false;
   }
   return read_misc_partition(data, size, misc_blk_device, SYSTEM_SPACE_OFFSET_IN_MISC + offset,
                              err);
 }

 static bool WriteMiscPartitionSystemSpace(const void* data, size_t size, size_t offset,
                                           std::string* err) {
   if (!ValidateSystemSpaceRegion(offset, size, err)) {
     return false;
   }
   auto misc_blk_device = get_misc_blk_device(err);
   if (misc_blk_device.empty()) {
     return false;
   }
   return write_misc_partition(data, size, misc_blk_device, SYSTEM_SPACE_OFFSET_IN_MISC + offset,
                               err);
 }

 bool ReadMiscVirtualAbMessage(misc_virtual_ab_message* message, std::string* err) {
   return ReadMiscPartitionSystemSpace(message, sizeof(*message),
                                       offsetof(misc_system_space_layout, virtual_ab_message), err);
 }

 bool WriteMiscVirtualAbMessage(const misc_virtual_ab_message& message, std::string* err) {
   return WriteMiscPartitionSystemSpace(&message, sizeof(message),
                                        offsetof(misc_system_space_layout, virtual_ab_message), err);
 }

 bool ReadMiscMemtagMessage(misc_memtag_message* message, std::string* err) {
   return ReadMiscPartitionSystemSpace(message, sizeof(*message),
                                       offsetof(misc_system_space_layout, memtag_message), err);
 }

 bool WriteMiscMemtagMessage(const misc_memtag_message& message, std::string* err) {
   return WriteMiscPartitionSystemSpace(&message, sizeof(message),
                                        offsetof(misc_system_space_layout, memtag_message), err);
 }

 bool ReadMiscKcmdlineMessage(misc_kcmdline_message* message, std::string* err) {
   return ReadMiscPartitionSystemSpace(message, sizeof(*message),
                                       offsetof(misc_system_space_layout, kcmdline_message), err);
 }

 bool WriteMiscKcmdlineMessage(const misc_kcmdline_message& message, std::string* err) {
   return WriteMiscPartitionSystemSpace(&message, sizeof(message),
                                        offsetof(misc_system_space_layout, kcmdline_message), err);
 }

 bool CheckReservedSystemSpaceEmpty(bool* empty, std::string* err) {
   constexpr size_t kReservedSize = SYSTEM_SPACE_SIZE_IN_MISC - sizeof(misc_system_space_layout);

   uint8_t space[kReservedSize];
   if (!ReadMiscPartitionSystemSpace(&space, kReservedSize, sizeof(misc_system_space_layout), err)) {
     return false;
   }

   *empty = space[0] == 0 && 0 == memcmp(space, space + 1, kReservedSize - 1);

   if (!*empty) {
     *err = android::base::HexString(space, kReservedSize);
   }

   return true;
 }

 extern "C" bool write_reboot_bootloader(void) {
   std::string err;
   return write_reboot_bootloader(&err);
 }

 extern "C" bool write_bootloader_message(const char* options) {
   std::string err;
   return write_bootloader_message({options}, &err);
 }
	/*
	* Copyright (C) 2016 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 <bootloader_message/bootloader_message.h>

	#include <errno.h>
	#include <fcntl.h>
	#include <string.h>

	#include <optional>
	#include <string>
	#include <string_view>
	#include <vector>

	#include <android-base/file.h>
	#include <android-base/hex.h>
	#include <android-base/properties.h>
	#include <android-base/stringprintf.h>
	#include <android-base/unique_fd.h>
	#include <fstab/fstab.h>

	#ifndef __ANDROID__
	#include <cutils/memory.h> // for strlcpy
	#endif

	using android::fs_mgr::Fstab;
	using android::fs_mgr::ReadDefaultFstab;

	static std::optional<std::string> g_misc_device_for_test;

	// Exposed for test purpose.
	void SetMiscBlockDeviceForTest(std::string_view misc_device) {
	g_misc_device_for_test = misc_device;
	}

	std::string get_misc_blk_device(std::string* err) {
	if (g_misc_device_for_test.has_value() && !g_misc_device_for_test->empty()) {
	return *g_misc_device_for_test;
	}
	Fstab fstab;
	if (!ReadDefaultFstab(&fstab)) {
	*err = "failed to read default fstab";
	return "";
	}
	for (const auto& entry : fstab) {
	if (entry.mount_point == "/misc") {
	return entry.blk_device;
	}
	}

	*err = "failed to find /misc partition";
	return "";
	}

	// In recovery mode, recovery can get started and try to access the misc
	// device before the kernel has actually created it.
	static bool wait_for_device(const std::string& blk_device, std::string* err) {
	int tries = 0;
	int ret;
	err->clear();
	do {
	++tries;
	struct stat buf;
	ret = stat(blk_device.c_str(), &buf);
	if (ret == -1) {
	*err += android::base::StringPrintf("failed to stat %s try %d: %s\n",
	blk_device.c_str(), tries, strerror(errno));
	sleep(1);
	}
	} while (ret && tries < 10);

	if (ret) {
	*err += android::base::StringPrintf("failed to stat %s\n", blk_device.c_str());
	}
	return ret == 0;
	}

	static bool read_misc_partition(void* p, size_t size, const std::string& misc_blk_device,
	size_t offset, std::string* err) {
	if (!wait_for_device(misc_blk_device, err)) {
	return false;
	}
	android::base::unique_fd fd(open(misc_blk_device.c_str(), O_RDONLY));
	if (fd == -1) {
	*err = android::base::StringPrintf("failed to open %s: %s", misc_blk_device.c_str(),
	strerror(errno));
	return false;
	}
	if (lseek(fd, static_cast<off_t>(offset), SEEK_SET) != static_cast<off_t>(offset)) {
	*err = android::base::StringPrintf("failed to lseek %s: %s", misc_blk_device.c_str(),
	strerror(errno));
	return false;
	}
	if (!android::base::ReadFully(fd, p, size)) {
	*err = android::base::StringPrintf("failed to read %s: %s", misc_blk_device.c_str(),
	strerror(errno));
	return false;
	}
	return true;
	}

	bool write_misc_partition(const void* p, size_t size, const std::string& misc_blk_device,
	size_t offset, std::string* err) {
	android::base::unique_fd fd(open(misc_blk_device.c_str(), O_WRONLY));
	if (fd == -1) {
	*err = android::base::StringPrintf("failed to open %s: %s", misc_blk_device.c_str(),
	strerror(errno));
	return false;
	}
	if (lseek(fd, static_cast<off_t>(offset), SEEK_SET) != static_cast<off_t>(offset)) {
	*err = android::base::StringPrintf("failed to lseek %s: %s", misc_blk_device.c_str(),
	strerror(errno));
	return false;
	}
	if (!android::base::WriteFully(fd, p, size)) {
	*err = android::base::StringPrintf("failed to write %s: %s", misc_blk_device.c_str(),
	strerror(errno));
	return false;
	}
	if (fsync(fd) == -1) {
	*err = android::base::StringPrintf("failed to fsync %s: %s", misc_blk_device.c_str(),
	strerror(errno));
	return false;
	}
	return true;
	}

	std::string get_bootloader_message_blk_device(std::string* err) {
	std::string misc_blk_device = get_misc_blk_device(err);
	if (misc_blk_device.empty()) return "";
	if (!wait_for_device(misc_blk_device, err)) return "";
	return misc_blk_device;
	}

	bool read_bootloader_message_from(bootloader_message* boot, const std::string& misc_blk_device,
	std::string* err) {
	return read_misc_partition(boot, sizeof(*boot), misc_blk_device,
	BOOTLOADER_MESSAGE_OFFSET_IN_MISC, err);
	}

	bool read_bootloader_message(bootloader_message* boot, std::string* err) {
	std::string misc_blk_device = get_misc_blk_device(err);
	if (misc_blk_device.empty()) {
	return false;
	}
	return read_bootloader_message_from(boot, misc_blk_device, err);
	}

	bool write_bootloader_message_to(const bootloader_message& boot, const std::string& misc_blk_device,
	std::string* err) {
	return write_misc_partition(&boot, sizeof(boot), misc_blk_device,
	BOOTLOADER_MESSAGE_OFFSET_IN_MISC, err);
	}

	bool write_bootloader_message(const bootloader_message& boot, std::string* err) {
	std::string misc_blk_device = get_misc_blk_device(err);
	if (misc_blk_device.empty()) {
	return false;
	}
	return write_bootloader_message_to(boot, misc_blk_device, err);
	}

	bool clear_bootloader_message(std::string* err) {
	bootloader_message boot = {};
	return write_bootloader_message(boot, err);
	}

	bool write_bootloader_message(const std::vector<std::string>& options, std::string* err) {
	bootloader_message boot = {};
	update_bootloader_message_in_struct(&boot, options);

	return write_bootloader_message(boot, err);
	}

	bool write_bootloader_message_to(const std::vector<std::string>& options,
	const std::string& misc_blk_device, std::string* err) {
	bootloader_message boot = {};
	update_bootloader_message_in_struct(&boot, options);

	return write_bootloader_message_to(boot, misc_blk_device, err);
	}

	bool update_bootloader_message(const std::vector<std::string>& options, std::string* err) {
	bootloader_message boot;
	if (!read_bootloader_message(&boot, err)) {
	return false;
	}
	update_bootloader_message_in_struct(&boot, options);

	return write_bootloader_message(boot, err);
	}

	bool update_bootloader_message_in_struct(bootloader_message* boot,
	const std::vector<std::string>& options) {
	if (!boot) return false;
	// Replace the command & recovery fields.
	memset(boot->command, 0, sizeof(boot->command));
	memset(boot->recovery, 0, sizeof(boot->recovery));

	strlcpy(boot->command, "boot-recovery", sizeof(boot->command));

	std::string recovery = "recovery\n";
	for (const auto& s : options) {
	recovery += s;
	if (s.back() != '\n') {
	recovery += '\n';
	}
	}
	strlcpy(boot->recovery, recovery.c_str(), sizeof(boot->recovery));
	return true;
	}

	bool write_reboot_bootloader(std::string* err) {
	bootloader_message boot;
	if (!read_bootloader_message(&boot, err)) {
	return false;
	}
	if (boot.command[0] != '\0') {
	*err = "Bootloader command pending.";
	return false;
	}
	strlcpy(boot.command, "bootonce-bootloader", sizeof(boot.command));
	return write_bootloader_message(boot, err);
	}

	bool read_wipe_package(std::string* package_data, size_t size, std::string* err) {
	std::string misc_blk_device = get_misc_blk_device(err);
	if (misc_blk_device.empty()) {
	return false;
	}
	package_data->resize(size);
	return read_misc_partition(&(*package_data)[0], size, misc_blk_device,
	WIPE_PACKAGE_OFFSET_IN_MISC, err);
	}

	bool write_wipe_package(const std::string& package_data, std::string* err) {
	std::string misc_blk_device = get_misc_blk_device(err);
	if (misc_blk_device.empty()) {
	return false;
	}
	static constexpr size_t kMaximumWipePackageSize =
	SYSTEM_SPACE_OFFSET_IN_MISC - WIPE_PACKAGE_OFFSET_IN_MISC;
	if (package_data.size() > kMaximumWipePackageSize) {
	*err = "Wipe package size " + std::to_string(package_data.size()) + " exceeds " +
	std::to_string(kMaximumWipePackageSize) + " bytes";
	return false;
	}
	return write_misc_partition(package_data.data(), package_data.size(), misc_blk_device,
	WIPE_PACKAGE_OFFSET_IN_MISC, err);
	}

	static bool ValidateSystemSpaceRegion(size_t offset, size_t size, std::string* err) {
	if (size <= SYSTEM_SPACE_SIZE_IN_MISC && offset <= (SYSTEM_SPACE_SIZE_IN_MISC - size)) {
	return true;
	}
	*err = android::base::StringPrintf("Out of bound access (offset %zu size %zu)", offset, size);
	return false;
	}

	static bool ReadMiscPartitionSystemSpace(void* data, size_t size, size_t offset, std::string* err) {
	if (!ValidateSystemSpaceRegion(offset, size, err)) {
	return false;
	}
	auto misc_blk_device = get_misc_blk_device(err);
	if (misc_blk_device.empty()) {
	return false;
	}
	return read_misc_partition(data, size, misc_blk_device, SYSTEM_SPACE_OFFSET_IN_MISC + offset,
	err);
	}

	static bool WriteMiscPartitionSystemSpace(const void* data, size_t size, size_t offset,
	std::string* err) {
	if (!ValidateSystemSpaceRegion(offset, size, err)) {
	return false;
	}
	auto misc_blk_device = get_misc_blk_device(err);
	if (misc_blk_device.empty()) {
	return false;
	}
	return write_misc_partition(data, size, misc_blk_device, SYSTEM_SPACE_OFFSET_IN_MISC + offset,
	err);
	}

	bool ReadMiscVirtualAbMessage(misc_virtual_ab_message* message, std::string* err) {
	return ReadMiscPartitionSystemSpace(message, sizeof(*message),
	offsetof(misc_system_space_layout, virtual_ab_message), err);
	}

	bool WriteMiscVirtualAbMessage(const misc_virtual_ab_message& message, std::string* err) {
	return WriteMiscPartitionSystemSpace(&message, sizeof(message),
	offsetof(misc_system_space_layout, virtual_ab_message), err);
	}

	bool ReadMiscMemtagMessage(misc_memtag_message* message, std::string* err) {
	return ReadMiscPartitionSystemSpace(message, sizeof(*message),
	offsetof(misc_system_space_layout, memtag_message), err);
	}

	bool WriteMiscMemtagMessage(const misc_memtag_message& message, std::string* err) {
	return WriteMiscPartitionSystemSpace(&message, sizeof(message),
	offsetof(misc_system_space_layout, memtag_message), err);
	}

	bool ReadMiscKcmdlineMessage(misc_kcmdline_message* message, std::string* err) {
	return ReadMiscPartitionSystemSpace(message, sizeof(*message),
	offsetof(misc_system_space_layout, kcmdline_message), err);
	}

	bool WriteMiscKcmdlineMessage(const misc_kcmdline_message& message, std::string* err) {
	return WriteMiscPartitionSystemSpace(&message, sizeof(message),
	offsetof(misc_system_space_layout, kcmdline_message), err);
	}

	bool CheckReservedSystemSpaceEmpty(bool* empty, std::string* err) {
	constexpr size_t kReservedSize = SYSTEM_SPACE_SIZE_IN_MISC - sizeof(misc_system_space_layout);

	uint8_t space[kReservedSize];
	if (!ReadMiscPartitionSystemSpace(&space, kReservedSize, sizeof(misc_system_space_layout), err)) {
	return false;
	}

	*empty = space[0] == 0 && 0 == memcmp(space, space + 1, kReservedSize - 1);

	if (!*empty) {
	*err = android::base::HexString(space, kReservedSize);
	}

	return true;
	}

	extern "C" bool write_reboot_bootloader(void) {
	std::string err;
	return write_reboot_bootloader(&err);
	}

	extern "C" bool write_bootloader_message(const char* options) {
	std::string err;
	return write_bootloader_message({options}, &err);
	}