| // |
| // Copyright (C) 2020 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. |
| // |
| |
| #include <sys/types.h> |
| #include <unistd.h> |
| |
| #include <limits> |
| #include <optional> |
| #include <set> |
| #include <unordered_map> |
| #include <unordered_set> |
| #include <vector> |
| |
| #include <android-base/file.h> |
| #include <android-base/logging.h> |
| #include <libsnapshot/cow_reader.h> |
| #include <zlib.h> |
| |
| #include "cow_decompress.h" |
| |
| namespace android { |
| namespace snapshot { |
| |
| CowReader::CowReader(ReaderFlags reader_flag) |
| : fd_(-1), |
| header_(), |
| fd_size_(0), |
| merge_op_blocks_(std::make_shared<std::vector<uint32_t>>()), |
| reader_flag_(reader_flag) {} |
| |
| static void SHA256(const void*, size_t, uint8_t[]) { |
| #if 0 |
| SHA256_CTX c; |
| SHA256_Init(&c); |
| SHA256_Update(&c, data, length); |
| SHA256_Final(out, &c); |
| #endif |
| } |
| |
| std::unique_ptr<CowReader> CowReader::CloneCowReader() { |
| auto cow = std::make_unique<CowReader>(); |
| cow->owned_fd_.reset(); |
| cow->header_ = header_; |
| cow->footer_ = footer_; |
| cow->fd_size_ = fd_size_; |
| cow->last_label_ = last_label_; |
| cow->ops_ = ops_; |
| cow->merge_op_blocks_ = merge_op_blocks_; |
| cow->merge_op_start_ = merge_op_start_; |
| cow->block_map_ = block_map_; |
| cow->num_total_data_ops_ = num_total_data_ops_; |
| cow->num_ordered_ops_to_merge_ = num_ordered_ops_to_merge_; |
| cow->has_seq_ops_ = has_seq_ops_; |
| cow->data_loc_ = data_loc_; |
| return cow; |
| } |
| |
| bool CowReader::InitForMerge(android::base::unique_fd&& fd) { |
| owned_fd_ = std::move(fd); |
| fd_ = owned_fd_.get(); |
| |
| auto pos = lseek(fd_.get(), 0, SEEK_END); |
| if (pos < 0) { |
| PLOG(ERROR) << "lseek end failed"; |
| return false; |
| } |
| fd_size_ = pos; |
| |
| if (lseek(fd_.get(), 0, SEEK_SET) < 0) { |
| PLOG(ERROR) << "lseek header failed"; |
| return false; |
| } |
| if (!android::base::ReadFully(fd_, &header_, sizeof(header_))) { |
| PLOG(ERROR) << "read header failed"; |
| return false; |
| } |
| |
| return true; |
| } |
| |
| bool CowReader::Parse(android::base::unique_fd&& fd, std::optional<uint64_t> label) { |
| owned_fd_ = std::move(fd); |
| return Parse(android::base::borrowed_fd{owned_fd_}, label); |
| } |
| |
| bool CowReader::Parse(android::base::borrowed_fd fd, std::optional<uint64_t> label) { |
| fd_ = fd; |
| |
| auto pos = lseek(fd_.get(), 0, SEEK_END); |
| if (pos < 0) { |
| PLOG(ERROR) << "lseek end failed"; |
| return false; |
| } |
| fd_size_ = pos; |
| |
| if (lseek(fd_.get(), 0, SEEK_SET) < 0) { |
| PLOG(ERROR) << "lseek header failed"; |
| return false; |
| } |
| if (!android::base::ReadFully(fd_, &header_, sizeof(header_))) { |
| PLOG(ERROR) << "read header failed"; |
| return false; |
| } |
| |
| if (header_.magic != kCowMagicNumber) { |
| LOG(ERROR) << "Header Magic corrupted. Magic: " << header_.magic |
| << "Expected: " << kCowMagicNumber; |
| return false; |
| } |
| if (header_.footer_size != sizeof(CowFooter)) { |
| LOG(ERROR) << "Footer size unknown, read " << header_.footer_size << ", expected " |
| << sizeof(CowFooter); |
| return false; |
| } |
| if (header_.op_size != sizeof(CowOperation)) { |
| LOG(ERROR) << "Operation size unknown, read " << header_.op_size << ", expected " |
| << sizeof(CowOperation); |
| return false; |
| } |
| if (header_.cluster_ops == 1) { |
| LOG(ERROR) << "Clusters must contain at least two operations to function."; |
| return false; |
| } |
| if (header_.op_size != sizeof(CowOperation)) { |
| LOG(ERROR) << "Operation size unknown, read " << header_.op_size << ", expected " |
| << sizeof(CowOperation); |
| return false; |
| } |
| if (header_.cluster_ops == 1) { |
| LOG(ERROR) << "Clusters must contain at least two operations to function."; |
| return false; |
| } |
| |
| if ((header_.major_version > kCowVersionMajor) || (header_.minor_version != kCowVersionMinor)) { |
| LOG(ERROR) << "Header version mismatch"; |
| LOG(ERROR) << "Major version: " << header_.major_version |
| << "Expected: " << kCowVersionMajor; |
| LOG(ERROR) << "Minor version: " << header_.minor_version |
| << "Expected: " << kCowVersionMinor; |
| return false; |
| } |
| |
| if (!ParseOps(label)) { |
| return false; |
| } |
| // If we're resuming a write, we're not ready to merge |
| if (label.has_value()) return true; |
| return PrepMergeOps(); |
| } |
| |
| bool CowReader::ParseOps(std::optional<uint64_t> label) { |
| uint64_t pos; |
| auto data_loc = std::make_shared<std::unordered_map<uint64_t, uint64_t>>(); |
| |
| // Skip the scratch space |
| if (header_.major_version >= 2 && (header_.buffer_size > 0)) { |
| LOG(DEBUG) << " Scratch space found of size: " << header_.buffer_size; |
| size_t init_offset = header_.header_size + header_.buffer_size; |
| pos = lseek(fd_.get(), init_offset, SEEK_SET); |
| if (pos != init_offset) { |
| PLOG(ERROR) << "lseek ops failed"; |
| return false; |
| } |
| } else { |
| pos = lseek(fd_.get(), header_.header_size, SEEK_SET); |
| if (pos != header_.header_size) { |
| PLOG(ERROR) << "lseek ops failed"; |
| return false; |
| } |
| // Reading a v1 version of COW which doesn't have buffer_size. |
| header_.buffer_size = 0; |
| } |
| uint64_t data_pos = 0; |
| |
| if (header_.cluster_ops) { |
| data_pos = pos + header_.cluster_ops * sizeof(CowOperation); |
| } else { |
| data_pos = pos + sizeof(CowOperation); |
| } |
| |
| auto ops_buffer = std::make_shared<std::vector<CowOperation>>(); |
| uint64_t current_op_num = 0; |
| uint64_t cluster_ops = header_.cluster_ops ?: 1; |
| bool done = false; |
| |
| // Alternating op clusters and data |
| while (!done) { |
| uint64_t to_add = std::min(cluster_ops, (fd_size_ - pos) / sizeof(CowOperation)); |
| if (to_add == 0) break; |
| ops_buffer->resize(current_op_num + to_add); |
| if (!android::base::ReadFully(fd_, &ops_buffer->data()[current_op_num], |
| to_add * sizeof(CowOperation))) { |
| PLOG(ERROR) << "read op failed"; |
| return false; |
| } |
| // Parse current cluster to find start of next cluster |
| while (current_op_num < ops_buffer->size()) { |
| auto& current_op = ops_buffer->data()[current_op_num]; |
| current_op_num++; |
| if (current_op.type == kCowXorOp) { |
| data_loc->insert({current_op.new_block, data_pos}); |
| } |
| pos += sizeof(CowOperation) + GetNextOpOffset(current_op, header_.cluster_ops); |
| data_pos += current_op.data_length + GetNextDataOffset(current_op, header_.cluster_ops); |
| |
| if (current_op.type == kCowClusterOp) { |
| break; |
| } else if (current_op.type == kCowLabelOp) { |
| last_label_ = {current_op.source}; |
| |
| // If we reach the requested label, stop reading. |
| if (label && label.value() == current_op.source) { |
| done = true; |
| break; |
| } |
| } else if (current_op.type == kCowFooterOp) { |
| footer_.emplace(); |
| CowFooter* footer = &footer_.value(); |
| memcpy(&footer_->op, ¤t_op, sizeof(footer->op)); |
| off_t offs = lseek(fd_.get(), pos, SEEK_SET); |
| if (offs < 0 || pos != static_cast<uint64_t>(offs)) { |
| PLOG(ERROR) << "lseek next op failed " << offs; |
| return false; |
| } |
| if (!android::base::ReadFully(fd_, &footer->data, sizeof(footer->data))) { |
| LOG(ERROR) << "Could not read COW footer"; |
| return false; |
| } |
| |
| // Drop the footer from the op stream. |
| current_op_num--; |
| done = true; |
| break; |
| } else if (current_op.type == kCowSequenceOp) { |
| has_seq_ops_ = true; |
| } |
| } |
| |
| // Position for next cluster read |
| off_t offs = lseek(fd_.get(), pos, SEEK_SET); |
| if (offs < 0 || pos != static_cast<uint64_t>(offs)) { |
| PLOG(ERROR) << "lseek next op failed " << offs; |
| return false; |
| } |
| ops_buffer->resize(current_op_num); |
| } |
| |
| LOG(DEBUG) << "COW file read complete. Total ops: " << ops_buffer->size(); |
| // To successfully parse a COW file, we need either: |
| // (1) a label to read up to, and for that label to be found, or |
| // (2) a valid footer. |
| if (label) { |
| if (!last_label_) { |
| LOG(ERROR) << "Did not find label " << label.value() |
| << " while reading COW (no labels found)"; |
| return false; |
| } |
| if (last_label_.value() != label.value()) { |
| LOG(ERROR) << "Did not find label " << label.value() |
| << ", last label=" << last_label_.value(); |
| return false; |
| } |
| } else if (!footer_) { |
| LOG(ERROR) << "No COW footer found"; |
| return false; |
| } |
| |
| uint8_t csum[32]; |
| memset(csum, 0, sizeof(uint8_t) * 32); |
| |
| if (footer_) { |
| if (ops_buffer->size() != footer_->op.num_ops) { |
| LOG(ERROR) << "num ops does not match, expected " << footer_->op.num_ops << ", found " |
| << ops_buffer->size(); |
| return false; |
| } |
| if (ops_buffer->size() * sizeof(CowOperation) != footer_->op.ops_size) { |
| LOG(ERROR) << "ops size does not match "; |
| return false; |
| } |
| SHA256(&footer_->op, sizeof(footer_->op), footer_->data.footer_checksum); |
| if (memcmp(csum, footer_->data.ops_checksum, sizeof(csum)) != 0) { |
| LOG(ERROR) << "ops checksum does not match"; |
| return false; |
| } |
| SHA256(ops_buffer->data(), footer_->op.ops_size, csum); |
| if (memcmp(csum, footer_->data.ops_checksum, sizeof(csum)) != 0) { |
| LOG(ERROR) << "ops checksum does not match"; |
| return false; |
| } |
| } |
| |
| ops_ = ops_buffer; |
| ops_->shrink_to_fit(); |
| data_loc_ = data_loc; |
| |
| return true; |
| } |
| |
| // |
| // This sets up the data needed for MergeOpIter. MergeOpIter presents |
| // data in the order we intend to merge in. |
| // |
| // We merge all order sensitive ops up front, and sort the rest to allow for |
| // batch merging. Order sensitive ops can either be presented in their proper |
| // order in the cow, or be ordered by sequence ops (kCowSequenceOp), in which |
| // case we want to merge those ops first, followed by any ops not specified by |
| // new_block value by the sequence op, in sorted order. |
| // We will re-arrange the vector in such a way that |
| // kernel can batch merge. Ex: |
| // |
| // Existing COW format; All the copy operations |
| // are at the beginning. |
| // ======================================= |
| // Copy-op-1 - cow_op->new_block = 1 |
| // Copy-op-2 - cow_op->new_block = 2 |
| // Copy-op-3 - cow_op->new_block = 3 |
| // Replace-op-4 - cow_op->new_block = 6 |
| // Replace-op-5 - cow_op->new_block = 4 |
| // Replace-op-6 - cow_op->new_block = 8 |
| // Replace-op-7 - cow_op->new_block = 9 |
| // Zero-op-8 - cow_op->new_block = 7 |
| // Zero-op-9 - cow_op->new_block = 5 |
| // ======================================= |
| // |
| // First find the operation which isn't a copy-op |
| // and then sort all the operations in descending order |
| // with the key being cow_op->new_block (source block) |
| // |
| // The data-structure will look like: |
| // |
| // ======================================= |
| // Copy-op-1 - cow_op->new_block = 1 |
| // Copy-op-2 - cow_op->new_block = 2 |
| // Copy-op-3 - cow_op->new_block = 3 |
| // Replace-op-7 - cow_op->new_block = 9 |
| // Replace-op-6 - cow_op->new_block = 8 |
| // Zero-op-8 - cow_op->new_block = 7 |
| // Replace-op-4 - cow_op->new_block = 6 |
| // Zero-op-9 - cow_op->new_block = 5 |
| // Replace-op-5 - cow_op->new_block = 4 |
| // ======================================= |
| // |
| // Daemon will read the above data-structure in reverse-order |
| // when reading metadata. Thus, kernel will get the metadata |
| // in the following order: |
| // |
| // ======================================== |
| // Replace-op-5 - cow_op->new_block = 4 |
| // Zero-op-9 - cow_op->new_block = 5 |
| // Replace-op-4 - cow_op->new_block = 6 |
| // Zero-op-8 - cow_op->new_block = 7 |
| // Replace-op-6 - cow_op->new_block = 8 |
| // Replace-op-7 - cow_op->new_block = 9 |
| // Copy-op-3 - cow_op->new_block = 3 |
| // Copy-op-2 - cow_op->new_block = 2 |
| // Copy-op-1 - cow_op->new_block = 1 |
| // =========================================== |
| // |
| // When merging begins, kernel will start from the last |
| // metadata which was read: In the above format, Copy-op-1 |
| // will be the first merge operation. |
| // |
| // Now, batching of the merge operations happens only when |
| // 1: origin block numbers in the base device are contiguous |
| // (cow_op->new_block) and, |
| // 2: cow block numbers which are assigned by daemon in ReadMetadata() |
| // are contiguous. These are monotonically increasing numbers. |
| // |
| // When both (1) and (2) are true, kernel will batch merge the operations. |
| // In the above case, we have to ensure that the copy operations |
| // are merged first before replace operations are done. Hence, |
| // we will not change the order of copy operations. Since, |
| // cow_op->new_block numbers are contiguous, we will ensure that the |
| // cow block numbers assigned in ReadMetadata() for these respective copy |
| // operations are not contiguous forcing kernel to issue merge for each |
| // copy operations without batch merging. |
| // |
| // For all the other operations viz. Replace and Zero op, the cow block |
| // numbers assigned by daemon will be contiguous allowing kernel to batch |
| // merge. |
| // |
| // The final format after assiging COW block numbers by the daemon will |
| // look something like: |
| // |
| // ========================================================= |
| // Replace-op-5 - cow_op->new_block = 4 cow-block-num = 2 |
| // Zero-op-9 - cow_op->new_block = 5 cow-block-num = 3 |
| // Replace-op-4 - cow_op->new_block = 6 cow-block-num = 4 |
| // Zero-op-8 - cow_op->new_block = 7 cow-block-num = 5 |
| // Replace-op-6 - cow_op->new_block = 8 cow-block-num = 6 |
| // Replace-op-7 - cow_op->new_block = 9 cow-block-num = 7 |
| // Copy-op-3 - cow_op->new_block = 3 cow-block-num = 9 |
| // Copy-op-2 - cow_op->new_block = 2 cow-block-num = 11 |
| // Copy-op-1 - cow_op->new_block = 1 cow-block-num = 13 |
| // ========================================================== |
| // |
| // Merge sequence will look like: |
| // |
| // Merge-1 - Batch-merge { Copy-op-1, Copy-op-2, Copy-op-3 } |
| // Merge-2 - Batch-merge {Replace-op-7, Replace-op-6, Zero-op-8, |
| // Replace-op-4, Zero-op-9, Replace-op-5 } |
| //============================================================== |
| bool CowReader::PrepMergeOps() { |
| auto merge_op_blocks = std::make_shared<std::vector<uint32_t>>(); |
| std::vector<int> other_ops; |
| auto seq_ops_set = std::unordered_set<uint32_t>(); |
| auto block_map = std::make_shared<std::unordered_map<uint32_t, int>>(); |
| size_t num_seqs = 0; |
| size_t read; |
| |
| for (size_t i = 0; i < ops_->size(); i++) { |
| auto& current_op = ops_->data()[i]; |
| |
| if (current_op.type == kCowSequenceOp) { |
| size_t seq_len = current_op.data_length / sizeof(uint32_t); |
| |
| merge_op_blocks->resize(merge_op_blocks->size() + seq_len); |
| if (!GetRawBytes(current_op.source, &merge_op_blocks->data()[num_seqs], |
| current_op.data_length, &read)) { |
| PLOG(ERROR) << "Failed to read sequence op!"; |
| return false; |
| } |
| for (size_t j = num_seqs; j < num_seqs + seq_len; j++) { |
| seq_ops_set.insert(merge_op_blocks->data()[j]); |
| } |
| num_seqs += seq_len; |
| } |
| |
| if (IsMetadataOp(current_op)) { |
| continue; |
| } |
| |
| if (!has_seq_ops_ && IsOrderedOp(current_op)) { |
| merge_op_blocks->emplace_back(current_op.new_block); |
| } else if (seq_ops_set.count(current_op.new_block) == 0) { |
| other_ops.push_back(current_op.new_block); |
| } |
| block_map->insert({current_op.new_block, i}); |
| } |
| for (auto block : *merge_op_blocks) { |
| if (block_map->count(block) == 0) { |
| LOG(ERROR) << "Invalid Sequence Ops. Could not find Cow Op for new block " << block; |
| return false; |
| } |
| } |
| |
| if (merge_op_blocks->size() > header_.num_merge_ops) { |
| num_ordered_ops_to_merge_ = merge_op_blocks->size() - header_.num_merge_ops; |
| } else { |
| num_ordered_ops_to_merge_ = 0; |
| } |
| |
| // Sort the vector in increasing order if merging in user-space as |
| // we can batch merge them when iterating from forward. |
| // |
| // dm-snapshot-merge requires decreasing order as we iterate the blocks |
| // in reverse order. |
| if (reader_flag_ == ReaderFlags::USERSPACE_MERGE) { |
| std::sort(other_ops.begin(), other_ops.end()); |
| } else { |
| std::sort(other_ops.begin(), other_ops.end(), std::greater<int>()); |
| } |
| |
| merge_op_blocks->insert(merge_op_blocks->end(), other_ops.begin(), other_ops.end()); |
| |
| num_total_data_ops_ = merge_op_blocks->size(); |
| if (header_.num_merge_ops > 0) { |
| merge_op_start_ = header_.num_merge_ops; |
| } |
| |
| block_map_ = block_map; |
| merge_op_blocks_ = merge_op_blocks; |
| return true; |
| } |
| |
| bool CowReader::VerifyMergeOps() { |
| auto itr = GetMergeOpIter(true); |
| std::unordered_map<uint64_t, CowOperation> overwritten_blocks; |
| while (!itr->Done()) { |
| CowOperation op = itr->Get(); |
| uint64_t block; |
| bool offset; |
| if (op.type == kCowCopyOp) { |
| block = op.source; |
| offset = false; |
| } else if (op.type == kCowXorOp) { |
| block = op.source / BLOCK_SZ; |
| offset = (op.source % BLOCK_SZ) != 0; |
| } else { |
| itr->Next(); |
| continue; |
| } |
| |
| CowOperation* overwrite = nullptr; |
| if (overwritten_blocks.count(block)) { |
| overwrite = &overwritten_blocks[block]; |
| LOG(ERROR) << "Invalid Sequence! Block needed for op:\n" |
| << op << "\noverwritten by previously merged op:\n" |
| << *overwrite; |
| } |
| if (offset && overwritten_blocks.count(block + 1)) { |
| overwrite = &overwritten_blocks[block + 1]; |
| LOG(ERROR) << "Invalid Sequence! Block needed for op:\n" |
| << op << "\noverwritten by previously merged op:\n" |
| << *overwrite; |
| } |
| if (overwrite != nullptr) return false; |
| overwritten_blocks[op.new_block] = op; |
| itr->Next(); |
| } |
| return true; |
| } |
| |
| bool CowReader::GetHeader(CowHeader* header) { |
| *header = header_; |
| return true; |
| } |
| |
| bool CowReader::GetFooter(CowFooter* footer) { |
| if (!footer_) return false; |
| *footer = footer_.value(); |
| return true; |
| } |
| |
| bool CowReader::GetLastLabel(uint64_t* label) { |
| if (!last_label_) return false; |
| *label = last_label_.value(); |
| return true; |
| } |
| |
| class CowOpIter final : public ICowOpIter { |
| public: |
| CowOpIter(std::shared_ptr<std::vector<CowOperation>>& ops); |
| |
| bool Done() override; |
| const CowOperation& Get() override; |
| void Next() override; |
| |
| private: |
| std::shared_ptr<std::vector<CowOperation>> ops_; |
| std::vector<CowOperation>::iterator op_iter_; |
| }; |
| |
| CowOpIter::CowOpIter(std::shared_ptr<std::vector<CowOperation>>& ops) { |
| ops_ = ops; |
| op_iter_ = ops_->begin(); |
| } |
| |
| bool CowOpIter::Done() { |
| return op_iter_ == ops_->end(); |
| } |
| |
| void CowOpIter::Next() { |
| CHECK(!Done()); |
| op_iter_++; |
| } |
| |
| const CowOperation& CowOpIter::Get() { |
| CHECK(!Done()); |
| return (*op_iter_); |
| } |
| |
| class CowRevMergeOpIter final : public ICowOpIter { |
| public: |
| explicit CowRevMergeOpIter(std::shared_ptr<std::vector<CowOperation>> ops, |
| std::shared_ptr<std::vector<uint32_t>> merge_op_blocks, |
| std::shared_ptr<std::unordered_map<uint32_t, int>> map, |
| uint64_t start); |
| |
| bool Done() override; |
| const CowOperation& Get() override; |
| void Next() override; |
| |
| private: |
| std::shared_ptr<std::vector<CowOperation>> ops_; |
| std::shared_ptr<std::vector<uint32_t>> merge_op_blocks_; |
| std::shared_ptr<std::unordered_map<uint32_t, int>> map_; |
| std::vector<uint32_t>::reverse_iterator block_riter_; |
| uint64_t start_; |
| }; |
| |
| class CowMergeOpIter final : public ICowOpIter { |
| public: |
| explicit CowMergeOpIter(std::shared_ptr<std::vector<CowOperation>> ops, |
| std::shared_ptr<std::vector<uint32_t>> merge_op_blocks, |
| std::shared_ptr<std::unordered_map<uint32_t, int>> map, uint64_t start); |
| |
| bool Done() override; |
| const CowOperation& Get() override; |
| void Next() override; |
| |
| private: |
| std::shared_ptr<std::vector<CowOperation>> ops_; |
| std::shared_ptr<std::vector<uint32_t>> merge_op_blocks_; |
| std::shared_ptr<std::unordered_map<uint32_t, int>> map_; |
| std::vector<uint32_t>::iterator block_iter_; |
| uint64_t start_; |
| }; |
| |
| CowMergeOpIter::CowMergeOpIter(std::shared_ptr<std::vector<CowOperation>> ops, |
| std::shared_ptr<std::vector<uint32_t>> merge_op_blocks, |
| std::shared_ptr<std::unordered_map<uint32_t, int>> map, |
| uint64_t start) { |
| ops_ = ops; |
| merge_op_blocks_ = merge_op_blocks; |
| map_ = map; |
| start_ = start; |
| |
| block_iter_ = merge_op_blocks->begin() + start; |
| } |
| |
| bool CowMergeOpIter::Done() { |
| return block_iter_ == merge_op_blocks_->end(); |
| } |
| |
| void CowMergeOpIter::Next() { |
| CHECK(!Done()); |
| block_iter_++; |
| } |
| |
| const CowOperation& CowMergeOpIter::Get() { |
| CHECK(!Done()); |
| return ops_->data()[map_->at(*block_iter_)]; |
| } |
| |
| CowRevMergeOpIter::CowRevMergeOpIter(std::shared_ptr<std::vector<CowOperation>> ops, |
| std::shared_ptr<std::vector<uint32_t>> merge_op_blocks, |
| std::shared_ptr<std::unordered_map<uint32_t, int>> map, |
| uint64_t start) { |
| ops_ = ops; |
| merge_op_blocks_ = merge_op_blocks; |
| map_ = map; |
| start_ = start; |
| |
| block_riter_ = merge_op_blocks->rbegin(); |
| } |
| |
| bool CowRevMergeOpIter::Done() { |
| return block_riter_ == merge_op_blocks_->rend() - start_; |
| } |
| |
| void CowRevMergeOpIter::Next() { |
| CHECK(!Done()); |
| block_riter_++; |
| } |
| |
| const CowOperation& CowRevMergeOpIter::Get() { |
| CHECK(!Done()); |
| return ops_->data()[map_->at(*block_riter_)]; |
| } |
| |
| std::unique_ptr<ICowOpIter> CowReader::GetOpIter() { |
| return std::make_unique<CowOpIter>(ops_); |
| } |
| |
| std::unique_ptr<ICowOpIter> CowReader::GetRevMergeOpIter(bool ignore_progress) { |
| return std::make_unique<CowRevMergeOpIter>(ops_, merge_op_blocks_, block_map_, |
| ignore_progress ? 0 : merge_op_start_); |
| } |
| |
| std::unique_ptr<ICowOpIter> CowReader::GetMergeOpIter(bool ignore_progress) { |
| return std::make_unique<CowMergeOpIter>(ops_, merge_op_blocks_, block_map_, |
| ignore_progress ? 0 : merge_op_start_); |
| } |
| |
| bool CowReader::GetRawBytes(uint64_t offset, void* buffer, size_t len, size_t* read) { |
| // Validate the offset, taking care to acknowledge possible overflow of offset+len. |
| if (offset < header_.header_size || offset >= fd_size_ - sizeof(CowFooter) || len >= fd_size_ || |
| offset + len > fd_size_ - sizeof(CowFooter)) { |
| LOG(ERROR) << "invalid data offset: " << offset << ", " << len << " bytes"; |
| return false; |
| } |
| if (lseek(fd_.get(), offset, SEEK_SET) < 0) { |
| PLOG(ERROR) << "lseek to read raw bytes failed"; |
| return false; |
| } |
| ssize_t rv = TEMP_FAILURE_RETRY(::read(fd_.get(), buffer, len)); |
| if (rv < 0) { |
| PLOG(ERROR) << "read failed"; |
| return false; |
| } |
| *read = rv; |
| return true; |
| } |
| |
| class CowDataStream final : public IByteStream { |
| public: |
| CowDataStream(CowReader* reader, uint64_t offset, size_t data_length) |
| : reader_(reader), offset_(offset), data_length_(data_length) { |
| remaining_ = data_length_; |
| } |
| |
| bool Read(void* buffer, size_t length, size_t* read) override { |
| size_t to_read = std::min(length, remaining_); |
| if (!to_read) { |
| *read = 0; |
| return true; |
| } |
| if (!reader_->GetRawBytes(offset_, buffer, to_read, read)) { |
| return false; |
| } |
| offset_ += *read; |
| remaining_ -= *read; |
| return true; |
| } |
| |
| size_t Size() const override { return data_length_; } |
| |
| private: |
| CowReader* reader_; |
| uint64_t offset_; |
| size_t data_length_; |
| size_t remaining_; |
| }; |
| |
| bool CowReader::ReadData(const CowOperation& op, IByteSink* sink) { |
| std::unique_ptr<IDecompressor> decompressor; |
| switch (op.compression) { |
| case kCowCompressNone: |
| decompressor = IDecompressor::Uncompressed(); |
| break; |
| case kCowCompressGz: |
| decompressor = IDecompressor::Gz(); |
| break; |
| case kCowCompressBrotli: |
| decompressor = IDecompressor::Brotli(); |
| break; |
| default: |
| LOG(ERROR) << "Unknown compression type: " << op.compression; |
| return false; |
| } |
| |
| uint64_t offset; |
| if (op.type == kCowXorOp) { |
| offset = data_loc_->at(op.new_block); |
| } else { |
| offset = op.source; |
| } |
| CowDataStream stream(this, offset, op.data_length); |
| decompressor->set_stream(&stream); |
| decompressor->set_sink(sink); |
| return decompressor->Decompress(header_.block_size); |
| } |
| |
| } // namespace snapshot |
| } // namespace android |
