| // 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 chromeos_update_engine { |
| class FileDescriptor; |
| } // namespace chromeos_update_engine |
| |
| namespace android { |
| namespace snapshot { |
| |
| class ICowOpIter; |
| |
| // Interface for reading from a snapuserd COW. |
| class ICowReader { |
| public: |
| using FileDescriptor = chromeos_update_engine::FileDescriptor; |
| |
| virtual ~ICowReader() {} |
| |
| // Return the file header. |
| virtual CowHeader& GetHeader() = 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. |
| // |
| // If ignore_bytes is non-zero, it specifies the initial number of bytes |
| // to skip writing to |buffer|. |
| // |
| // Returns the number of bytes written to |buffer|, or -1 on failure. |
| // errno is NOT set. |
| // |
| // Partial reads are not possible unless |buffer_size| is less than the |
| // operation block size. |
| // |
| // The operation pointer must derive from ICowOpIter::Get(). |
| virtual ssize_t ReadData(const CowOperation* op, void* buffer, size_t buffer_size, |
| size_t ignore_bytes = 0) = 0; |
| |
| // Get the absolute source offset, in bytes, of a CowOperation. Returns |
| // false if the operation does not read from source partitions. |
| virtual bool GetSourceOffset(const CowOperation* op, uint64_t* source_offset) = 0; |
| }; |
| |
| static constexpr uint64_t GetBlockFromOffset(const CowHeader& header, uint64_t offset) { |
| return offset / header.block_size; |
| } |
| |
| static constexpr uint64_t GetBlockRelativeOffset(const CowHeader& header, uint64_t offset) { |
| return offset % header.block_size; |
| } |
| |
| // Iterate over a sequence of COW operations. The iterator is bidirectional. |
| class ICowOpIter { |
| public: |
| virtual ~ICowOpIter() {} |
| |
| // Returns true if the iterator is at the end of the operation list. |
| // If true, Get() and Next() must not be called. |
| virtual bool AtEnd() = 0; |
| |
| // Read the current operation. |
| virtual const CowOperation* Get() = 0; |
| |
| // Advance to the next item. |
| virtual void Next() = 0; |
| |
| // Returns true if the iterator is at the beginning of the operation list. |
| // If true, Prev() must not be called; Get() however will be valid if |
| // AtEnd() is not true. |
| virtual bool AtBegin() = 0; |
| |
| // Advance to the previous item. |
| virtual void Prev() = 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 GetFooter(CowFooter* footer) override; |
| bool GetLastLabel(uint64_t* label) override; |
| bool GetSourceOffset(const CowOperation* op, uint64_t* source_offset) 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; |
| |
| ssize_t ReadData(const CowOperation* op, void* buffer, size_t buffer_size, |
| size_t ignore_bytes = 0) override; |
| |
| CowHeader& GetHeader() override { return header_; } |
| |
| bool GetRawBytes(const CowOperation* op, void* buffer, size_t len, size_t* read); |
| 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(); |
| uint8_t GetCompressionType(const CowOperation* op); |
| |
| 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 |