Merge "create_snapshot: Create snapshot patch comparing two partition images" into main

fs_mgr/libsnapshot/Android.bp

@@ -446,6 +446,38 @@ cc_binary {
     ],
 }
 
+cc_binary {
+    name: "create_snapshot",
+    host_supported: true,
+    device_supported: false,
+
+    srcs: ["libsnapshot_cow/create_cow.cpp"],
+
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+
+    static_libs: [
+        "liblog",
+        "libbase",
+        "libext4_utils",
+        "libsnapshot_cow",
+        "libcrypto",
+        "libbrotli",
+        "libz",
+        "liblz4",
+        "libzstd",
+        "libgflags",
+    ],
+    shared_libs: [
+    ],
+
+    header_libs: [
+        "libstorage_literals_headers",
+    ],
+}
+
 python_library_host {
     name: "snapshot_proto_python",
     srcs: [

fs_mgr/libsnapshot/libsnapshot_cow/create_cow.cpp

@@ -0,0 +1,359 @@
+#include <linux/types.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/resource.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <condition_variable>
+#include <cstring>
+#include <future>
+#include <iostream>
+#include <limits>
+#include <mutex>
+#include <string>
+#include <thread>
+#include <unordered_map>
+#include <vector>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/stringprintf.h>
+#include <android-base/unique_fd.h>
+#include <ext4_utils/ext4_utils.h>
+#include <storage_literals/storage_literals.h>
+
+#include <android-base/chrono_utils.h>
+#include <android-base/scopeguard.h>
+#include <android-base/strings.h>
+
+#include <gflags/gflags.h>
+#include <libsnapshot/cow_writer.h>
+
+#include <openssl/sha.h>
+
+DEFINE_string(source, "", "Source partition image");
+DEFINE_string(target, "", "Target partition image");
+DEFINE_string(compression, "lz4",
+              "Compression algorithm. Default is set to lz4. Available options: lz4, zstd, gz");
+
+namespace android {
+namespace snapshot {
+
+using namespace android::storage_literals;
+using namespace android;
+using android::base::unique_fd;
+
+using android::snapshot::CreateCowWriter;
+using android::snapshot::ICowWriter;
+
+class CreateSnapshot {
+  public:
+    CreateSnapshot(const std::string& src_file, const std::string& target_file,
+                   const std::string& patch_file, const std::string& compression);
+    bool CreateSnapshotPatch();
+
+  private:
+    /* source.img */
+    std::string src_file_;
+    /* target.img */
+    std::string target_file_;
+    /* snapshot-patch generated */
+    std::string patch_file_;
+
+    /*
+     * Active file which is being parsed by this instance.
+     * It will either be source.img or target.img.
+     */
+    std::string parsing_file_;
+    bool create_snapshot_patch_ = false;
+
+    const int kNumThreads = 6;
+    const size_t kBlockSizeToRead = 1_MiB;
+
+    std::unordered_map<std::string, int> source_block_hash_;
+    std::mutex source_block_hash_lock_;
+
+    std::unique_ptr<ICowWriter> writer_;
+    std::mutex write_lock_;
+
+    std::unique_ptr<uint8_t[]> zblock_;
+
+    std::string compression_ = "lz4";
+    unique_fd fd_;
+
+    const int BLOCK_SZ = 4_KiB;
+    void SHA256(const void* data, size_t length, uint8_t out[32]);
+    bool IsBlockAligned(uint64_t read_size) { return ((read_size & (BLOCK_SZ - 1)) == 0); }
+    bool ReadBlocks(off_t offset, const int skip_blocks, const uint64_t dev_sz);
+    std::string ToHexString(const uint8_t* buf, size_t len);
+
+    bool CreateSnapshotFile();
+    bool FindSourceBlockHash();
+    bool PrepareParse(std::string& parsing_file, const bool createSnapshot);
+    bool ParsePartition();
+    bool WriteSnapshot(const void* buffer, uint64_t block, std::string& block_hash);
+};
+
+void CreateSnapshotLogger(android::base::LogId, android::base::LogSeverity severity, const char*,
+                          const char*, unsigned int, const char* message) {
+    if (severity == android::base::ERROR) {
+        fprintf(stderr, "%s\n", message);
+    } else {
+        fprintf(stdout, "%s\n", message);
+    }
+}
+
+CreateSnapshot::CreateSnapshot(const std::string& src_file, const std::string& target_file,
+                               const std::string& patch_file, const std::string& compression)
+    : src_file_(src_file), target_file_(target_file), patch_file_(patch_file) {
+    if (!compression.empty()) {
+        compression_ = compression;
+    }
+}
+
+bool CreateSnapshot::PrepareParse(std::string& parsing_file, const bool createSnapshot) {
+    parsing_file_ = parsing_file;
+    create_snapshot_patch_ = createSnapshot;
+
+    if (createSnapshot) {
+        fd_.reset(open(patch_file_.c_str(), O_RDWR | O_CREAT | O_TRUNC, 0666));
+        if (fd_ < 0) {
+            PLOG(ERROR) << "Failed to open the snapshot-patch file: " << patch_file_;
+            return false;
+        }
+
+        zblock_ = std::make_unique<uint8_t[]>(BLOCK_SZ);
+        std::memset(zblock_.get(), 0, BLOCK_SZ);
+
+        CowOptions options;
+        options.compression = compression_;
+        options.num_compress_threads = 2;
+        options.batch_write = true;
+        options.cluster_ops = 600;
+        writer_ = CreateCowWriter(2, options, std::move(fd_));
+    }
+    return true;
+}
+
+/*
+ * Create per-block sha256 hash of source partition
+ */
+bool CreateSnapshot::FindSourceBlockHash() {
+    if (!PrepareParse(src_file_, false)) {
+        return false;
+    }
+    return ParsePartition();
+}
+
+/*
+ * Create snapshot file by comparing sha256 per block
+ * of target.img with the constructed per-block sha256 hash
+ * of source partition.
+ */
+bool CreateSnapshot::CreateSnapshotFile() {
+    if (!PrepareParse(target_file_, true)) {
+        return false;
+    }
+    return ParsePartition();
+}
+
+/*
+ * Creates snapshot patch file by comparing source.img and target.img
+ */
+bool CreateSnapshot::CreateSnapshotPatch() {
+    if (!FindSourceBlockHash()) {
+        return false;
+    }
+    return CreateSnapshotFile();
+}
+
+void CreateSnapshot::SHA256(const void* data, size_t length, uint8_t out[32]) {
+    SHA256_CTX c;
+    SHA256_Init(&c);
+    SHA256_Update(&c, data, length);
+    SHA256_Final(out, &c);
+}
+
+std::string CreateSnapshot::ToHexString(const uint8_t* buf, size_t len) {
+    char lookup[] = "0123456789abcdef";
+    std::string out(len * 2 + 1, '\0');
+    char* outp = out.data();
+    for (; len > 0; len--, buf++) {
+        *outp++ = (char)lookup[*buf >> 4];
+        *outp++ = (char)lookup[*buf & 0xf];
+    }
+    return out;
+}
+
+bool CreateSnapshot::WriteSnapshot(const void* buffer, uint64_t block, std::string& block_hash) {
+    if (std::memcmp(zblock_.get(), buffer, BLOCK_SZ) == 0) {
+        std::lock_guard<std::mutex> lock(write_lock_);
+        return writer_->AddZeroBlocks(block, 1);
+    }
+
+    auto iter = source_block_hash_.find(block_hash);
+    if (iter != source_block_hash_.end()) {
+        std::lock_guard<std::mutex> lock(write_lock_);
+        return writer_->AddCopy(block, iter->second, 1);
+    }
+    std::lock_guard<std::mutex> lock(write_lock_);
+    return writer_->AddRawBlocks(block, buffer, BLOCK_SZ);
+}
+
+bool CreateSnapshot::ReadBlocks(off_t offset, const int skip_blocks, const uint64_t dev_sz) {
+    unique_fd fd(TEMP_FAILURE_RETRY(open(parsing_file_.c_str(), O_RDONLY)));
+    if (fd < 0) {
+        LOG(ERROR) << "open failed: " << parsing_file_;
+        return false;
+    }
+
+    loff_t file_offset = offset;
+    const uint64_t read_sz = kBlockSizeToRead;
+    std::unique_ptr<uint8_t[]> buffer = std::make_unique<uint8_t[]>(read_sz);
+
+    while (true) {
+        size_t to_read = std::min((dev_sz - file_offset), read_sz);
+
+        if (!android::base::ReadFullyAtOffset(fd.get(), buffer.get(), to_read, file_offset)) {
+            LOG(ERROR) << "Failed to read block from block device: " << parsing_file_
+                       << " at offset: " << file_offset << " read-size: " << to_read
+                       << " block-size: " << dev_sz;
+            return false;
+        }
+
+        if (!IsBlockAligned(to_read)) {
+            LOG(ERROR) << "unable to parse the un-aligned request: " << to_read;
+            return false;
+        }
+
+        size_t num_blocks = to_read / BLOCK_SZ;
+        uint64_t buffer_offset = 0;
+        off_t foffset = file_offset;
+
+        while (num_blocks) {
+            const void* bufptr = (char*)buffer.get() + buffer_offset;
+            uint64_t blkindex = foffset / BLOCK_SZ;
+
+            uint8_t checksum[32];
+            SHA256(bufptr, BLOCK_SZ, checksum);
+            std::string hash = ToHexString(checksum, sizeof(checksum));
+
+            if (create_snapshot_patch_ && !WriteSnapshot(bufptr, blkindex, hash)) {
+                LOG(ERROR) << "WriteSnapshot failed for block: " << blkindex;
+                return false;
+            } else {
+                std::lock_guard<std::mutex> lock(source_block_hash_lock_);
+                {
+                    if (source_block_hash_.count(hash) == 0) {
+                        source_block_hash_[hash] = blkindex;
+                    }
+                }
+            }
+            buffer_offset += BLOCK_SZ;
+            foffset += BLOCK_SZ;
+            num_blocks -= 1;
+        }
+
+        file_offset += (skip_blocks * kBlockSizeToRead);
+        if (file_offset >= dev_sz) {
+            break;
+        }
+    }
+
+    return true;
+}
+
+bool CreateSnapshot::ParsePartition() {
+    unique_fd fd(TEMP_FAILURE_RETRY(open(parsing_file_.c_str(), O_RDONLY)));
+    if (fd < 0) {
+        LOG(ERROR) << "open failed: " << parsing_file_;
+        return false;
+    }
+
+    uint64_t dev_sz = lseek(fd.get(), 0, SEEK_END);
+    if (!dev_sz) {
+        LOG(ERROR) << "Could not determine block device size: " << parsing_file_;
+        return false;
+    }
+
+    if (!IsBlockAligned(dev_sz)) {
+        LOG(ERROR) << "dev_sz: " << dev_sz << " is not block aligned";
+        return false;
+    }
+
+    int num_threads = kNumThreads;
+
+    std::vector<std::future<bool>> threads;
+    off_t start_offset = 0;
+    const int skip_blocks = num_threads;
+
+    while (num_threads) {
+        threads.emplace_back(std::async(std::launch::async, &CreateSnapshot::ReadBlocks, this,
+                                        start_offset, skip_blocks, dev_sz));
+        start_offset += kBlockSizeToRead;
+        num_threads -= 1;
+        if (start_offset >= dev_sz) {
+            break;
+        }
+    }
+
+    bool ret = true;
+    for (auto& t : threads) {
+        ret = t.get() && ret;
+    }
+
+    if (ret && create_snapshot_patch_ && !writer_->Finalize()) {
+        LOG(ERROR) << "Finzalize failed";
+        return false;
+    }
+
+    return ret;
+}
+
+}  // namespace snapshot
+}  // namespace android
+
+constexpr char kUsage[] = R"(
+NAME
+    create_snapshot - Create snapshot patches by comparing two partition images
+
+SYNOPSIS
+    create_snapshot --source=<source.img> --target=<target.img> --compression="<compression-algorithm"
+
+    source.img -> Source partition image
+    target.img -> Target partition image
+    compressoin -> compression algorithm. Default set to lz4. Supported types are gz, lz4, zstd.
+
+EXAMPLES
+
+   $ create_snapshot $SOURCE_BUILD/system.img $TARGET_BUILD/system.img
+   $ create_snapshot $SOURCE_BUILD/product.img $TARGET_BUILD/product.img --compression="zstd"
+
+)";
+
+int main(int argc, char* argv[]) {
+    android::base::InitLogging(argv, &android::snapshot::CreateSnapshotLogger);
+    ::gflags::SetUsageMessage(kUsage);
+    ::gflags::ParseCommandLineFlags(&argc, &argv, true);
+
+    if (FLAGS_source.empty() || FLAGS_target.empty()) {
+        LOG(INFO) << kUsage;
+        return 0;
+    }
+
+    std::string fname = android::base::Basename(FLAGS_target.c_str());
+    auto parts = android::base::Split(fname, ".");
+    std::string snapshotfile = parts[0] + ".patch";
+    android::snapshot::CreateSnapshot snapshot(FLAGS_source, FLAGS_target, snapshotfile,
+                                               FLAGS_compression);
+
+    if (!snapshot.CreateSnapshotPatch()) {
+        LOG(ERROR) << "Snapshot creation failed";
+        return -1;
+    }
+
+    LOG(INFO) << "Snapshot patch: " << snapshotfile << " created successfully";
+    return 0;
+}