| // Copyright (C) 2019 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 <stdint.h> |
| |
| #include <functional> |
| #include <memory> |
| #include <optional> |
| #include <unordered_map> |
| |
| #include <android-base/unique_fd.h> |
| #include <libsnapshot/cow_format.h> |
| |
| namespace android { |
| namespace snapshot { |
| |
| class ICowOpIter; |
| |
| // A ByteSink object handles requests for a buffer of a specific size. It |
| // always owns the underlying buffer. It's designed to minimize potential |
| // copying as we parse or decompress the COW. |
| class IByteSink { |
| public: |
| virtual ~IByteSink() {} |
| |
| // Called when the reader has data. The size of the request is given. The |
| // sink must return a valid pointer (or null on failure), and return the |
| // maximum number of bytes that can be written to the returned buffer. |
| // |
| // The returned buffer is owned by IByteSink, but must remain valid until |
| // the read operation has completed (or the entire buffer has been |
| // covered by calls to ReturnData). |
| // |
| // After calling GetBuffer(), all previous buffers returned are no longer |
| // valid. |
| // |
| // GetBuffer() is intended to be sequential. A returned size of N indicates |
| // that the output stream will advance by N bytes, and the ReturnData call |
| // indicates that those bytes have been fulfilled. Therefore, it is |
| // possible to have ReturnBuffer do nothing, if the implementation doesn't |
| // care about incremental writes. |
| virtual void* GetBuffer(size_t requested, size_t* actual) = 0; |
| |
| // Called when a section returned by |GetBuffer| has been filled with data. |
| virtual bool ReturnData(void* buffer, size_t length) = 0; |
| }; |
| |
| // Interface for reading from a snapuserd COW. |
| class ICowReader { |
| public: |
| virtual ~ICowReader() {} |
| |
| // Return the file header. |
| virtual bool GetHeader(CowHeader* header) = 0; |
| |
| // Return the file footer. |
| virtual bool GetFooter(CowFooter* footer) = 0; |
| virtual bool VerifyMergeOps() = 0; |
| |
| // Return the last valid label |
| virtual bool GetLastLabel(uint64_t* label) = 0; |
| |
| // Return an iterator for retrieving CowOperation entries. |
| virtual std::unique_ptr<ICowOpIter> GetOpIter(bool merge_progress) = 0; |
| |
| // Return an iterator for retrieving CowOperation entries in reverse merge order |
| virtual std::unique_ptr<ICowOpIter> GetRevMergeOpIter(bool ignore_progress) = 0; |
| |
| // Return an iterator for retrieving CowOperation entries in merge order |
| virtual std::unique_ptr<ICowOpIter> GetMergeOpIter(bool ignore_progress) = 0; |
| |
| // Get decoded bytes from the data section, handling any decompression. |
| // All retrieved data is passed to the sink. |
| virtual bool ReadData(const CowOperation& op, IByteSink* sink) = 0; |
| }; |
| |
| // Iterate over a sequence of COW operations. |
| class ICowOpIter { |
| public: |
| virtual ~ICowOpIter() {} |
| |
| // True if there are no more items to read forward, false otherwise. |
| virtual bool Done() = 0; |
| |
| // Read the current operation. |
| virtual const CowOperation& Get() = 0; |
| |
| // Advance to the next item. |
| virtual void Next() = 0; |
| |
| // Advance to the previous item. |
| virtual void Prev() = 0; |
| |
| // True if there are no more items to read backwards, false otherwise |
| virtual bool RDone() = 0; |
| }; |
| |
| class CowReader final : public ICowReader { |
| public: |
| enum class ReaderFlags { |
| DEFAULT = 0, |
| USERSPACE_MERGE = 1, |
| }; |
| |
| CowReader(ReaderFlags reader_flag = ReaderFlags::DEFAULT, bool is_merge = false); |
| ~CowReader() { owned_fd_ = {}; } |
| |
| // Parse the COW, optionally, up to the given label. If no label is |
| // specified, the COW must have an intact footer. |
| bool Parse(android::base::unique_fd&& fd, std::optional<uint64_t> label = {}); |
| bool Parse(android::base::borrowed_fd fd, std::optional<uint64_t> label = {}); |
| |
| bool InitForMerge(android::base::unique_fd&& fd); |
| bool VerifyMergeOps() override; |
| |
| bool GetHeader(CowHeader* header) override; |
| bool GetFooter(CowFooter* footer) override; |
| |
| bool GetLastLabel(uint64_t* label) override; |
| |
| // Create a CowOpIter object which contains footer_.num_ops |
| // CowOperation objects. Get() returns a unique CowOperation object |
| // whose lifetime depends on the CowOpIter object; the return |
| // value of these will never be null. |
| std::unique_ptr<ICowOpIter> GetOpIter(bool merge_progress = false) override; |
| std::unique_ptr<ICowOpIter> GetRevMergeOpIter(bool ignore_progress = false) override; |
| std::unique_ptr<ICowOpIter> GetMergeOpIter(bool ignore_progress = false) override; |
| |
| bool ReadData(const CowOperation& op, IByteSink* sink) override; |
| |
| bool GetRawBytes(uint64_t offset, void* buffer, size_t len, size_t* read); |
| |
| // Returns the total number of data ops that should be merged. This is the |
| // count of the merge sequence before removing already-merged operations. |
| // It may be different than the actual data op count, for example, if there |
| // are duplicate ops in the stream. |
| uint64_t get_num_total_data_ops() { return num_total_data_ops_; } |
| |
| uint64_t get_num_ordered_ops_to_merge() { return num_ordered_ops_to_merge_; } |
| |
| void CloseCowFd() { owned_fd_ = {}; } |
| |
| // Creates a clone of the current CowReader without the file handlers |
| std::unique_ptr<CowReader> CloneCowReader(); |
| |
| void UpdateMergeOpsCompleted(int num_merge_ops) { header_.num_merge_ops += num_merge_ops; } |
| |
| private: |
| bool ParseOps(std::optional<uint64_t> label); |
| bool PrepMergeOps(); |
| uint64_t FindNumCopyops(); |
| |
| android::base::unique_fd owned_fd_; |
| android::base::borrowed_fd fd_; |
| CowHeader header_; |
| std::optional<CowFooter> footer_; |
| uint64_t fd_size_; |
| std::optional<uint64_t> last_label_; |
| std::shared_ptr<std::vector<CowOperation>> ops_; |
| uint64_t merge_op_start_{}; |
| std::shared_ptr<std::vector<int>> block_pos_index_; |
| uint64_t num_total_data_ops_{}; |
| uint64_t num_ordered_ops_to_merge_{}; |
| bool has_seq_ops_{}; |
| std::shared_ptr<std::unordered_map<uint64_t, uint64_t>> data_loc_; |
| ReaderFlags reader_flag_; |
| bool is_merge_{}; |
| }; |
| |
| } // namespace snapshot |
| } // namespace android |