Merge "libsnapshot: Add Parser base class" into main

fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h

@@ -185,7 +185,6 @@ class CowReader final : public ICowReader {
     std::shared_ptr<std::unordered_map<uint64_t, uint64_t>> data_loc_;
     ReaderFlags reader_flag_;
     bool is_merge_{};
-    uint8_t compression_type_ = kCowCompressNone;
 };
 
 // Though this function takes in a CowHeaderV3, the struct could be populated as a v1/v2 CowHeader.

fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp

@@ -28,7 +28,6 @@
 #include <zlib.h>
 
 #include "cow_decompress.h"
-#include "libsnapshot/cow_format.h"
 #include "parser_v2.h"
 
 namespace android {
@@ -85,7 +84,6 @@ std::unique_ptr<CowReader> CowReader::CloneCowReader() {
     cow->data_loc_ = data_loc_;
     cow->block_pos_index_ = block_pos_index_;
     cow->is_merge_ = is_merge_;
-    cow->compression_type_ = compression_type_;
     return cow;
 }
 
@@ -104,11 +102,14 @@ bool CowReader::InitForMerge(android::base::unique_fd&& fd) {
         PLOG(ERROR) << "lseek header failed";
         return false;
     }
-    if (!android::base::ReadFully(fd_, &header_, sizeof(header_))) {
+
+    CHECK_GE(header_.prefix.header_size, sizeof(CowHeader));
+    CHECK_LE(header_.prefix.header_size, sizeof(header_));
+
+    if (!android::base::ReadFully(fd_, &header_, header_.prefix.header_size)) {
         PLOG(ERROR) << "read header failed";
         return false;
     }
-
     return true;
 }
 
@@ -124,52 +125,35 @@ bool CowReader::Parse(android::base::borrowed_fd fd, std::optional<uint64_t> lab
         return false;
     }
 
-    CowParserV2 parser;
-    if (!parser.Parse(fd, header_, label)) {
+    std::unique_ptr<CowParserBase> parser;
+    switch (header_.prefix.major_version) {
+        case 1:
+        case 2:
+            parser = std::make_unique<CowParserV2>();
+            break;
+        case 3:
+            break;
+        default:
+            LOG(ERROR) << "Unknown version: " << header_.prefix.major_version;
+            return false;
+    }
+
+    if (!parser->Parse(fd, header_, label)) {
         return false;
     }
 
-    footer_ = parser.footer();
-    fd_size_ = parser.fd_size();
-    last_label_ = parser.last_label();
-    data_loc_ = parser.data_loc();
-    ops_ = std::make_shared<std::vector<CowOperation>>(parser.ops()->size());
-
-    // Translate the operation buffer from on disk to in memory
-    for (size_t i = 0; i < parser.ops()->size(); i++) {
-        const auto& v2_op = parser.ops()->at(i);
-
-        auto& new_op = ops_->at(i);
-        new_op.type = v2_op.type;
-        new_op.data_length = v2_op.data_length;
-
-        if (v2_op.new_block > std::numeric_limits<uint32_t>::max()) {
-            LOG(ERROR) << "Out-of-range new block in COW op: " << v2_op;
-            return false;
-        }
-        new_op.new_block = v2_op.new_block;
-
-        uint64_t source_info = v2_op.source;
-        if (new_op.type != kCowLabelOp) {
-            source_info &= kCowOpSourceInfoDataMask;
-            if (source_info != v2_op.source) {
-                LOG(ERROR) << "Out-of-range source value in COW op: " << v2_op;
-                return false;
-            }
-        }
-        if (v2_op.compression != kCowCompressNone) {
-            if (compression_type_ == kCowCompressNone) {
-                compression_type_ = v2_op.compression;
-            } else if (compression_type_ != v2_op.compression) {
-                LOG(ERROR) << "COW has mixed compression types which is not supported;"
-                           << " previously saw " << compression_type_ << ", got "
-                           << v2_op.compression << ", op: " << v2_op;
-                return false;
-            }
-        }
-        new_op.source_info = source_info;
+    TranslatedCowOps ops_info;
+    if (!parser->Translate(&ops_info)) {
+        return false;
     }
 
+    header_ = ops_info.header;
+    ops_ = std::move(ops_info.ops);
+    footer_ = parser->footer();
+    fd_size_ = parser->fd_size();
+    last_label_ = parser->last_label();
+    data_loc_ = parser->data_loc();
+
     // If we're resuming a write, we're not ready to merge
     if (label.has_value()) return true;
     return PrepMergeOps();
@@ -664,7 +648,7 @@ class CowDataStream final : public IByteStream {
 };
 
 uint8_t CowReader::GetCompressionType() {
-    return compression_type_;
+    return header_.compression_algorithm;
 }
 
 ssize_t CowReader::ReadData(const CowOperation* op, void* buffer, size_t buffer_size,

fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp

@@ -74,13 +74,13 @@ static void ShowBad(CowReader& reader, const CowOperation* op) {
     }
 }
 
-static bool ShowRawOpStreamV2(borrowed_fd fd, const CowHeader& header) {
+static bool ShowRawOpStreamV2(borrowed_fd fd, const CowHeaderV3& header) {
     CowParserV2 parser;
     if (!parser.Parse(fd, header)) {
         LOG(ERROR) << "v2 parser failed";
         return false;
     }
-    for (const auto& op : *parser.ops()) {
+    for (const auto& op : *parser.get_v2ops()) {
         std::cout << op << "\n";
         if (auto iter = parser.data_loc()->find(op.new_block); iter != parser.data_loc()->end()) {
             std::cout << "    data loc: " << iter->second << "\n";

fs_mgr/libsnapshot/libsnapshot_cow/parser_base.h

@@ -0,0 +1,53 @@
+//
+// Copyright (C) 2023 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.
+//
+
+#pragma once
+
+#include <optional>
+#include <unordered_map>
+
+#include <android-base/unique_fd.h>
+#include <libsnapshot/cow_format.h>
+
+namespace android {
+namespace snapshot {
+
+struct TranslatedCowOps {
+    CowHeaderV3 header;
+    std::shared_ptr<std::vector<CowOperationV3>> ops;
+};
+
+class CowParserBase {
+  public:
+    virtual ~CowParserBase() = default;
+
+    virtual bool Parse(android::base::borrowed_fd fd, const CowHeaderV3& header,
+                       std::optional<uint64_t> label = {}) = 0;
+    virtual bool Translate(TranslatedCowOps* out) = 0;
+    virtual std::optional<CowFooter> footer() const { return std::nullopt; }
+    virtual std::shared_ptr<std::unordered_map<uint64_t, uint64_t>> data_loc() const = 0;
+
+    uint64_t fd_size() const { return fd_size_; }
+    const std::optional<uint64_t>& last_label() const { return last_label_; }
+
+  protected:
+    CowHeaderV3 header_ = {};
+    uint64_t fd_size_;
+    std::optional<uint64_t> last_label_;
+};
+
+}  // namespace snapshot
+}  // namespace android

fs_mgr/libsnapshot/libsnapshot_cow/parser_v2.cpp

@@ -18,12 +18,14 @@
 #include <android-base/file.h>
 #include <android-base/logging.h>
 
+#include <libsnapshot/cow_format.h>
+
 namespace android {
 namespace snapshot {
 
 using android::base::borrowed_fd;
 
-bool CowParserV2::Parse(borrowed_fd fd, const CowHeader& header, std::optional<uint64_t> label) {
+bool CowParserV2::Parse(borrowed_fd fd, const CowHeaderV3& header, std::optional<uint64_t> label) {
     auto pos = lseek(fd.get(), 0, SEEK_END);
     if (pos < 0) {
         PLOG(ERROR) << "lseek end failed";
@@ -47,8 +49,7 @@ bool CowParserV2::Parse(borrowed_fd fd, const CowHeader& header, std::optional<u
         return false;
     }
 
-    if ((header_.prefix.major_version > kCowVersionMajor) ||
-        (header_.prefix.minor_version != kCowVersionMinor)) {
+    if (header_.prefix.major_version > 2 || header_.prefix.minor_version != 0) {
         LOG(ERROR) << "Header version mismatch, "
                    << "major version: " << header_.prefix.major_version
                    << ", expected: " << kCowVersionMajor
@@ -190,11 +191,57 @@ bool CowParserV2::ParseOps(borrowed_fd fd, std::optional<uint64_t> label) {
         }
     }
 
-    ops_ = ops_buffer;
-    ops_->shrink_to_fit();
+    v2_ops_ = ops_buffer;
+    v2_ops_->shrink_to_fit();
     data_loc_ = data_loc;
     return true;
 }
 
+bool CowParserV2::Translate(TranslatedCowOps* out) {
+    out->ops = std::make_shared<std::vector<CowOperationV3>>(v2_ops_->size());
+
+    // Translate the operation buffer from on disk to in memory
+    for (size_t i = 0; i < out->ops->size(); i++) {
+        const auto& v2_op = v2_ops_->at(i);
+
+        auto& new_op = out->ops->at(i);
+        new_op.type = v2_op.type;
+        new_op.data_length = v2_op.data_length;
+
+        if (v2_op.new_block > std::numeric_limits<uint32_t>::max()) {
+            LOG(ERROR) << "Out-of-range new block in COW op: " << v2_op;
+            return false;
+        }
+        new_op.new_block = v2_op.new_block;
+
+        uint64_t source_info = v2_op.source;
+        if (new_op.type != kCowLabelOp) {
+            source_info &= kCowOpSourceInfoDataMask;
+            if (source_info != v2_op.source) {
+                LOG(ERROR) << "Out-of-range source value in COW op: " << v2_op;
+                return false;
+            }
+        }
+        if (v2_op.compression != kCowCompressNone) {
+            if (header_.compression_algorithm == kCowCompressNone) {
+                header_.compression_algorithm = v2_op.compression;
+            } else if (header_.compression_algorithm != v2_op.compression) {
+                LOG(ERROR) << "COW has mixed compression types which is not supported;"
+                           << " previously saw " << header_.compression_algorithm << ", got "
+                           << v2_op.compression << ", op: " << v2_op;
+                return false;
+            }
+        }
+        new_op.source_info = source_info;
+    }
+
+    out->header = header_;
+    return true;
+}
+
+std::shared_ptr<std::unordered_map<uint64_t, uint64_t>> CowParserV2::data_loc() const {
+    return data_loc_;
+}
+
 }  // namespace snapshot
 }  // namespace android

fs_mgr/libsnapshot/libsnapshot_cow/parser_v2.h

@@ -17,36 +17,31 @@
 
 #include <memory>
 #include <optional>
-#include <unordered_map>
 #include <vector>
 
 #include <android-base/unique_fd.h>
 #include <libsnapshot/cow_format.h>
+#include "parser_base.h"
 
 namespace android {
 namespace snapshot {
 
-class CowParserV2 {
+class CowParserV2 final : public CowParserBase {
   public:
-    bool Parse(android::base::borrowed_fd fd, const CowHeader& header,
-               std::optional<uint64_t> label = {});
+    bool Parse(android::base::borrowed_fd fd, const CowHeaderV3& header,
+               std::optional<uint64_t> label = {}) override;
+    bool Translate(TranslatedCowOps* out) override;
+    std::optional<CowFooter> footer() const override { return footer_; }
 
     const CowHeader& header() const { return header_; }
-    const std::optional<CowFooter>& footer() const { return footer_; }
-    std::shared_ptr<std::vector<CowOperationV2>> ops() { return ops_; }
-    std::shared_ptr<std::unordered_map<uint64_t, uint64_t>> data_loc() const { return data_loc_; }
-    uint64_t fd_size() const { return fd_size_; }
-    const std::optional<uint64_t>& last_label() const { return last_label_; }
+    std::shared_ptr<std::vector<CowOperationV2>> get_v2ops() { return v2_ops_; }
+    std::shared_ptr<std::unordered_map<uint64_t, uint64_t>> data_loc() const override;
 
   private:
-    bool ParseOps(android::base::borrowed_fd fd, std::optional<uint64_t> label);
-
-    CowHeader header_ = {};
-    std::optional<CowFooter> footer_;
-    std::shared_ptr<std::vector<CowOperationV2>> ops_;
     std::shared_ptr<std::unordered_map<uint64_t, uint64_t>> data_loc_;
-    uint64_t fd_size_;
-    std::optional<uint64_t> last_label_;
+    bool ParseOps(android::base::borrowed_fd fd, std::optional<uint64_t> label);
+    std::shared_ptr<std::vector<CowOperationV2>> v2_ops_;
+    std::optional<CowFooter> footer_;
 };
 
 }  // namespace snapshot

fs_mgr/libsnapshot/libsnapshot_cow/writer_v2.cpp

@@ -273,10 +273,11 @@ bool CowWriterV2::OpenForAppend(uint64_t label) {
     if (!ReadCowHeader(fd_, &header_v3)) {
         return false;
     }
+
     header_ = header_v3;
 
     CowParserV2 parser;
-    if (!parser.Parse(fd_, header_, {label})) {
+    if (!parser.Parse(fd_, header_v3, {label})) {
         return false;
     }
     if (header_.prefix.major_version > 2) {
@@ -292,7 +293,7 @@ bool CowWriterV2::OpenForAppend(uint64_t label) {
     footer_.op.num_ops = 0;
     InitPos();
 
-    for (const auto& op : *parser.ops()) {
+    for (const auto& op : *parser.get_v2ops()) {
         AddOperation(op);
     }
 

fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp

@@ -112,7 +112,7 @@ bool SnapshotHandler::CommitMerge(int num_merge_ops) {
             return false;
         }
 
-        if (!android::base::WriteFully(cow_fd_, &header, sizeof(CowHeader))) {
+        if (!android::base::WriteFully(cow_fd_, &header, header.prefix.header_size)) {
             SNAP_PLOG(ERROR) << "Write to header failed";
             return false;
         }