Checkpoint.cpp - SHIFTPHONES/android_system_vold - Gitiles

 /*
  * Copyright (C) 2018 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.
  */

 #define LOG_TAG "Checkpoint"
 #include "Checkpoint.h"

 #include <fstream>
 #include <list>
 #include <string>
 #include <vector>

 #include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/parseint.h>
 #include <android-base/unique_fd.h>
 #include <cutils/android_reboot.h>
 #include <fcntl.h>
 #include <fs_mgr.h>
 #include <linux/fs.h>
 #include <mntent.h>
 #include <sys/mount.h>
 #include <sys/stat.h>

 namespace android {
 namespace vold {

 namespace {
 const std::string kMetadataCPFile = "/metadata/vold/checkpoint";

 bool setBowState(std::string const& block_device, std::string const& state) {
     if (block_device.substr(0, 5) != "/dev/") {
         LOG(ERROR) << "Expected block device, got " << block_device;
         return false;
     }

     std::string state_filename = std::string("/sys/") + block_device.substr(5) + "/bow/state";
     if (!android::base::WriteStringToFile(state, state_filename)) {
         PLOG(ERROR) << "Failed to write to file " << state_filename;
         return false;
     }

     return true;
 }

 }  // namespace

 bool cp_startCheckpoint(int retry) {
     if (retry < -1) return false;
     std::string content = std::to_string(retry);
     return android::base::WriteStringToFile(content, kMetadataCPFile);
 }

 bool cp_commitChanges() {
     // Must take action for list of mounted checkpointed things here
     // To do this, we walk the list of mounted file systems.
     // But we also need to get the matching fstab entries to see
     // the original flags
     struct fstab* fstab = fs_mgr_read_fstab_default();
     if (!fstab) return false;

     struct fstab* mounts = fs_mgr_read_fstab("/proc/mounts");
     if (mounts == NULL) {
         fs_mgr_free_fstab(fstab);
         return false;
     }

     // Walk mounted file systems
     for (int i = 0; i < mounts->num_entries; ++i) {
         const fstab_rec* mount_rec = &mounts->recs[i];
         const fstab_rec* fstab_rec = fs_mgr_get_entry_for_mount_point(fstab, mount_rec->mount_point);
         if (!fstab_rec) continue;

         if (fs_mgr_is_checkpoint_fs(fstab_rec)) {
             if (!strcmp(fstab_rec->fs_type, "f2fs")) {
                 mount(mount_rec->blk_device, mount_rec->mount_point, "none",
                       MS_REMOUNT | fstab_rec->flags, "checkpoint=enable");
             }
         } else if (fs_mgr_is_checkpoint_blk(fstab_rec)) {
             setBowState(mount_rec->blk_device, "2");
         }
     }
     fs_mgr_free_fstab(mounts);
     fs_mgr_free_fstab(fstab);
     return android::base::RemoveFileIfExists(kMetadataCPFile);
 }

 void cp_abortChanges() {
     android_reboot(ANDROID_RB_RESTART2, 0, nullptr);
 }

 bool cp_needRollback(const std::string& id) {
     std::string content;
     bool ret;

     ret = android::base::ReadFileToString(kMetadataCPFile, &content);
     if (ret) return content == "0";
     return false;
 }

 bool cp_needsCheckpoint(void) {
     bool ret;
     std::string content;

     ret = android::base::ReadFileToString(kMetadataCPFile, &content);
     if (ret) return content != "0";
     return false;
 }

 bool cp_prepareDriveForCheckpoint(const std::string&) {
     struct fstab* fstab = fs_mgr_read_fstab_default();
     if (!fstab) return false;

     struct fstab* mounts = fs_mgr_read_fstab("/proc/mounts");
     if (mounts == NULL) {
         fs_mgr_free_fstab(fstab);
         return false;
     }

     for (int i = 0; i < mounts->num_entries; ++i) {
         const fstab_rec* mount_rec = &mounts->recs[i];
         const fstab_rec* fstab_rec = fs_mgr_get_entry_for_mount_point(fstab, mount_rec->mount_point);
         if (!fstab_rec) continue;

         if (fs_mgr_is_checkpoint_blk(fstab_rec)) {
             android::base::unique_fd fd(
                 TEMP_FAILURE_RETRY(open(mount_rec->mount_point, O_RDONLY | O_CLOEXEC)));
             if (!fd) {
                 PLOG(ERROR) << "Failed to open mount point" << mount_rec->mount_point;
                 continue;
             }

             struct fstrim_range range = {};
             range.len = ULLONG_MAX;
             if (ioctl(fd, FITRIM, &range)) {
                 PLOG(ERROR) << "Failed to trim " << mount_rec->mount_point;
                 continue;
             }

             setBowState(mount_rec->blk_device, "1");
         }
     }
     fs_mgr_free_fstab(mounts);
     fs_mgr_free_fstab(fstab);
     return true;
 }

 namespace {
 const int kBlockSize = 4096;
 const int kSectorSize = 512;

 typedef uint64_t sector_t;

 struct log_entry {
     sector_t source;
     sector_t dest;
     uint32_t size;
     uint32_t checksum;
 } __attribute__((packed));

 struct log_sector {
     uint32_t magic;
     uint32_t count;
     uint32_t sequence;
     struct log_entry entries[];
 } __attribute__((packed));

 // MAGIC is BOW in ascii
 const int kMagic = 0x00574f42;

 void crc32(const void* data, size_t n_bytes, uint32_t* crc) {
     static uint32_t table[0x100] = {
         0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535,
         0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD,
         0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D,
         0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC,
         0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4,
         0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C,
         0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC,
         0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
         0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB,
         0xB6662D3D,

         0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5,
         0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
         0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED,
         0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C,
         0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, 0x4DB26158, 0x3AB551CE, 0xA3BC0074,
         0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC,
         0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C,
         0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
         0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B,
         0xC0BA6CAD,

         0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615,
         0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D,
         0x0A00AE27, 0x7D079EB1, 0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D,
         0x806567CB, 0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
         0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4,
         0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, 0xD80D2BDA, 0xAF0A1B4C,
         0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79, 0xCB61B38C,
         0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
         0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B,
         0x5BDEAE1D,

         0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785,
         0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D,
         0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD,
         0xF6B9265B, 0x6FB077E1, 0x18B74777, 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
         0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354,
         0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC,
         0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, 0xBDBDF21C,
         0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
         0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B,
         0x2D02EF8D};

     for (size_t i = 0; i < n_bytes; ++i) {
         *crc ^= ((uint8_t*)data)[i];
         *crc = table[(uint8_t)*crc] ^ *crc >> 8;
     }
 }

 }  // namespace

 bool cp_restoreCheckpoint(const std::string& blockDevice) {
     LOG(ERROR) << "Restoring checkpoint on " << blockDevice;
     std::fstream device(blockDevice, std::ios::binary | std::ios::in | std::ios::out);
     if (!device) {
         PLOG(ERROR) << "Cannot open " << blockDevice;
         return false;
     }
     char buffer[kBlockSize];
     device.read(buffer, kBlockSize);
     log_sector& ls = *(log_sector*)buffer;
     if (ls.magic != kMagic) {
         LOG(ERROR) << "No magic";
         return false;
     }

     LOG(INFO) << "Restoring " << ls.sequence << " log sectors";

     for (int sequence = ls.sequence; sequence >= 0; sequence--) {
         char buffer[kBlockSize];
         device.seekg(0);
         device.read(buffer, kBlockSize);
         log_sector& ls = *(log_sector*)buffer;
         if (ls.magic != kMagic) {
             LOG(ERROR) << "No magic!";
             return false;
         }

         if ((int)ls.sequence != sequence) {
             LOG(ERROR) << "Expecting log sector " << sequence << " but got " << ls.sequence;
             return false;
         }

         LOG(INFO) << "Restoring from log sector " << ls.sequence;

         for (log_entry* le = &ls.entries[ls.count - 1]; le >= ls.entries; --le) {
             LOG(INFO) << "Restoring " << le->size << " bytes from sector " << le->dest << " to "
                       << le->source << " with checksum " << std::hex << le->checksum;
             std::vector<char> buffer(le->size);
             device.seekg(le->dest * kSectorSize);
             device.read(&buffer[0], le->size);

             uint32_t checksum = le->source / (kBlockSize / kSectorSize);
             for (size_t i = 0; i < le->size; i += kBlockSize) {
                 crc32(&buffer[i], kBlockSize, &checksum);
             }

             if (le->checksum && checksum != le->checksum) {
                 LOG(ERROR) << "Checksums don't match " << std::hex << checksum;
                 return false;
             }

             device.seekg(le->source * kSectorSize);
             device.write(&buffer[0], le->size);
         }
     }

     return true;
 }

 bool cp_markBootAttempt() {
     std::string oldContent, newContent;
     int retry = 0;
     if (!android::base::ReadFileToString(kMetadataCPFile, &oldContent)) return false;

     if (!android::base::ParseInt(oldContent, &retry)) return false;
     if (retry > 0) retry--;

     newContent = std::to_string(retry);
     return android::base::WriteStringToFile(newContent, kMetadataCPFile);
 }

 }  // namespace vold
 }  // namespace android
	/*
	* Copyright (C) 2018 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.
	*/

	#define LOG_TAG "Checkpoint"
	#include "Checkpoint.h"

	#include <fstream>
	#include <list>
	#include <string>
	#include <vector>

	#include <android-base/file.h>
	#include <android-base/logging.h>
	#include <android-base/parseint.h>
	#include <android-base/unique_fd.h>
	#include <cutils/android_reboot.h>
	#include <fcntl.h>
	#include <fs_mgr.h>
	#include <linux/fs.h>
	#include <mntent.h>
	#include <sys/mount.h>
	#include <sys/stat.h>

	namespace android {
	namespace vold {

	namespace {
	const std::string kMetadataCPFile = "/metadata/vold/checkpoint";

	bool setBowState(std::string const& block_device, std::string const& state) {
	if (block_device.substr(0, 5) != "/dev/") {
	LOG(ERROR) << "Expected block device, got " << block_device;
	return false;
	}

	std::string state_filename = std::string("/sys/") + block_device.substr(5) + "/bow/state";
	if (!android::base::WriteStringToFile(state, state_filename)) {
	PLOG(ERROR) << "Failed to write to file " << state_filename;
	return false;
	}

	return true;
	}

	} // namespace

	bool cp_startCheckpoint(int retry) {
	if (retry < -1) return false;
	std::string content = std::to_string(retry);
	return android::base::WriteStringToFile(content, kMetadataCPFile);
	}

	bool cp_commitChanges() {
	// Must take action for list of mounted checkpointed things here
	// To do this, we walk the list of mounted file systems.
	// But we also need to get the matching fstab entries to see
	// the original flags
	struct fstab* fstab = fs_mgr_read_fstab_default();
	if (!fstab) return false;

	struct fstab* mounts = fs_mgr_read_fstab("/proc/mounts");
	if (mounts == NULL) {
	fs_mgr_free_fstab(fstab);
	return false;
	}

	// Walk mounted file systems
	for (int i = 0; i < mounts->num_entries; ++i) {
	const fstab_rec* mount_rec = &mounts->recs[i];
	const fstab_rec* fstab_rec = fs_mgr_get_entry_for_mount_point(fstab, mount_rec->mount_point);
	if (!fstab_rec) continue;

	if (fs_mgr_is_checkpoint_fs(fstab_rec)) {
	if (!strcmp(fstab_rec->fs_type, "f2fs")) {
	mount(mount_rec->blk_device, mount_rec->mount_point, "none",
	MS_REMOUNT \| fstab_rec->flags, "checkpoint=enable");
	}
	} else if (fs_mgr_is_checkpoint_blk(fstab_rec)) {
	setBowState(mount_rec->blk_device, "2");
	}
	}
	fs_mgr_free_fstab(mounts);
	fs_mgr_free_fstab(fstab);
	return android::base::RemoveFileIfExists(kMetadataCPFile);
	}

	void cp_abortChanges() {
	android_reboot(ANDROID_RB_RESTART2, 0, nullptr);
	}

	bool cp_needRollback(const std::string& id) {
	std::string content;
	bool ret;

	ret = android::base::ReadFileToString(kMetadataCPFile, &content);
	if (ret) return content == "0";
	return false;
	}

	bool cp_needsCheckpoint(void) {
	bool ret;
	std::string content;

	ret = android::base::ReadFileToString(kMetadataCPFile, &content);
	if (ret) return content != "0";
	return false;
	}

	bool cp_prepareDriveForCheckpoint(const std::string&) {
	struct fstab* fstab = fs_mgr_read_fstab_default();
	if (!fstab) return false;

	struct fstab* mounts = fs_mgr_read_fstab("/proc/mounts");
	if (mounts == NULL) {
	fs_mgr_free_fstab(fstab);
	return false;
	}

	for (int i = 0; i < mounts->num_entries; ++i) {
	const fstab_rec* mount_rec = &mounts->recs[i];
	const fstab_rec* fstab_rec = fs_mgr_get_entry_for_mount_point(fstab, mount_rec->mount_point);
	if (!fstab_rec) continue;

	if (fs_mgr_is_checkpoint_blk(fstab_rec)) {
	android::base::unique_fd fd(
	TEMP_FAILURE_RETRY(open(mount_rec->mount_point, O_RDONLY \| O_CLOEXEC)));
	if (!fd) {
	PLOG(ERROR) << "Failed to open mount point" << mount_rec->mount_point;
	continue;
	}

	struct fstrim_range range = {};
	range.len = ULLONG_MAX;
	if (ioctl(fd, FITRIM, &range)) {
	PLOG(ERROR) << "Failed to trim " << mount_rec->mount_point;
	continue;
	}

	setBowState(mount_rec->blk_device, "1");
	}
	}
	fs_mgr_free_fstab(mounts);
	fs_mgr_free_fstab(fstab);
	return true;
	}

	namespace {
	const int kBlockSize = 4096;
	const int kSectorSize = 512;

	typedef uint64_t sector_t;

	struct log_entry {
	sector_t source;
	sector_t dest;
	uint32_t size;
	uint32_t checksum;
	} __attribute__((packed));

	struct log_sector {
	uint32_t magic;
	uint32_t count;
	uint32_t sequence;
	struct log_entry entries[];
	} __attribute__((packed));

	// MAGIC is BOW in ascii
	const int kMagic = 0x00574f42;

	void crc32(const void* data, size_t n_bytes, uint32_t* crc) {
	static uint32_t table[0x100] = {
	0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535,
	0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD,
	0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D,
	0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC,
	0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4,
	0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C,
	0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC,
	0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
	0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB,
	0xB6662D3D,

	0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5,
	0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
	0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED,
	0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C,
	0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, 0x4DB26158, 0x3AB551CE, 0xA3BC0074,
	0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC,
	0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C,
	0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
	0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B,
	0xC0BA6CAD,

	0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615,
	0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D,
	0x0A00AE27, 0x7D079EB1, 0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D,
	0x806567CB, 0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
	0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4,
	0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, 0xD80D2BDA, 0xAF0A1B4C,
	0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79, 0xCB61B38C,
	0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
	0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B,
	0x5BDEAE1D,

	0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785,
	0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D,
	0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD,
	0xF6B9265B, 0x6FB077E1, 0x18B74777, 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
	0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354,
	0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC,
	0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, 0xBDBDF21C,
	0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
	0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B,
	0x2D02EF8D};

	for (size_t i = 0; i < n_bytes; ++i) {
	crc ^= ((uint8_t)data)[i];
	crc = table[(uint8_t)crc] ^ *crc >> 8;
	}
	}

	} // namespace

	bool cp_restoreCheckpoint(const std::string& blockDevice) {
	LOG(ERROR) << "Restoring checkpoint on " << blockDevice;
	std::fstream device(blockDevice, std::ios::binary \| std::ios::in \| std::ios::out);
	if (!device) {
	PLOG(ERROR) << "Cannot open " << blockDevice;
	return false;
	}
	char buffer[kBlockSize];
	device.read(buffer, kBlockSize);
	log_sector& ls = (log_sector)buffer;
	if (ls.magic != kMagic) {
	LOG(ERROR) << "No magic";
	return false;
	}

	LOG(INFO) << "Restoring " << ls.sequence << " log sectors";

	for (int sequence = ls.sequence; sequence >= 0; sequence--) {
	char buffer[kBlockSize];
	device.seekg(0);
	device.read(buffer, kBlockSize);
	log_sector& ls = (log_sector)buffer;
	if (ls.magic != kMagic) {
	LOG(ERROR) << "No magic!";
	return false;
	}

	if ((int)ls.sequence != sequence) {
	LOG(ERROR) << "Expecting log sector " << sequence << " but got " << ls.sequence;
	return false;
	}

	LOG(INFO) << "Restoring from log sector " << ls.sequence;

	for (log_entry* le = &ls.entries[ls.count - 1]; le >= ls.entries; --le) {
	LOG(INFO) << "Restoring " << le->size << " bytes from sector " << le->dest << " to "
	<< le->source << " with checksum " << std::hex << le->checksum;
	std::vector<char> buffer(le->size);
	device.seekg(le->dest * kSectorSize);
	device.read(&buffer[0], le->size);

	uint32_t checksum = le->source / (kBlockSize / kSectorSize);
	for (size_t i = 0; i < le->size; i += kBlockSize) {
	crc32(&buffer[i], kBlockSize, &checksum);
	}

	if (le->checksum && checksum != le->checksum) {
	LOG(ERROR) << "Checksums don't match " << std::hex << checksum;
	return false;
	}

	device.seekg(le->source * kSectorSize);
	device.write(&buffer[0], le->size);
	}
	}

	return true;
	}

	bool cp_markBootAttempt() {
	std::string oldContent, newContent;
	int retry = 0;
	if (!android::base::ReadFileToString(kMetadataCPFile, &oldContent)) return false;

	if (!android::base::ParseInt(oldContent, &retry)) return false;
	if (retry > 0) retry--;

	newContent = std::to_string(retry);
	return android::base::WriteStringToFile(newContent, kMetadataCPFile);
	}

	} // namespace vold
	} // namespace android