134 lines
4.3 KiB
C++
134 lines
4.3 KiB
C++
//
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// Copyright (C) 2009 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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#ifndef UPDATE_ENGINE_PAYLOAD_CONSUMER_EXTENT_WRITER_H_
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#define UPDATE_ENGINE_PAYLOAD_CONSUMER_EXTENT_WRITER_H_
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#include <vector>
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#include <base/logging.h>
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#include <brillo/secure_blob.h>
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#include "update_engine/common/utils.h"
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#include "update_engine/payload_consumer/file_descriptor.h"
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#include "update_engine/update_metadata.pb.h"
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// ExtentWriter is an abstract class which synchronously writes to a given
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// file descriptor at the extents given.
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namespace chromeos_update_engine {
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class ExtentWriter {
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public:
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ExtentWriter() = default;
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virtual ~ExtentWriter() {
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LOG_IF(ERROR, !end_called_) << "End() not called on ExtentWriter.";
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}
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// Returns true on success.
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virtual bool Init(FileDescriptorPtr fd,
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const std::vector<Extent>& extents,
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uint32_t block_size) = 0;
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// Returns true on success.
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virtual bool Write(const void* bytes, size_t count) = 0;
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// Should be called when all writing is complete. Returns true on success.
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// The fd is not closed. Caller is responsible for closing it.
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bool End() {
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end_called_ = true;
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return EndImpl();
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}
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virtual bool EndImpl() = 0;
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private:
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bool end_called_{false};
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};
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// DirectExtentWriter is probably the simplest ExtentWriter implementation.
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// It writes the data directly into the extents.
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class DirectExtentWriter : public ExtentWriter {
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public:
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DirectExtentWriter() = default;
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~DirectExtentWriter() override = default;
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bool Init(FileDescriptorPtr fd,
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const std::vector<Extent>& extents,
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uint32_t block_size) override {
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fd_ = fd;
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block_size_ = block_size;
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extents_ = extents;
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return true;
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}
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bool Write(const void* bytes, size_t count) override;
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bool EndImpl() override { return true; }
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private:
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FileDescriptorPtr fd_{nullptr};
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size_t block_size_{0};
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// Bytes written into next_extent_index_ thus far
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uint64_t extent_bytes_written_{0};
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std::vector<Extent> extents_;
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// The next call to write should correspond to extents_[next_extent_index_]
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std::vector<Extent>::size_type next_extent_index_{0};
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};
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// Takes an underlying ExtentWriter to which all operations are delegated.
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// When End() is called, ZeroPadExtentWriter ensures that the total number
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// of bytes written is a multiple of block_size_. If not, it writes zeros
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// to pad as needed.
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class ZeroPadExtentWriter : public ExtentWriter {
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public:
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explicit ZeroPadExtentWriter(
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std::unique_ptr<ExtentWriter> underlying_extent_writer)
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: underlying_extent_writer_(std::move(underlying_extent_writer)) {}
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~ZeroPadExtentWriter() override = default;
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bool Init(FileDescriptorPtr fd,
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const std::vector<Extent>& extents,
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uint32_t block_size) override {
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block_size_ = block_size;
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return underlying_extent_writer_->Init(fd, extents, block_size);
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}
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bool Write(const void* bytes, size_t count) override {
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if (underlying_extent_writer_->Write(bytes, count)) {
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bytes_written_mod_block_size_ += count;
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bytes_written_mod_block_size_ %= block_size_;
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return true;
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}
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return false;
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}
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bool EndImpl() override {
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if (bytes_written_mod_block_size_) {
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const size_t write_size = block_size_ - bytes_written_mod_block_size_;
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brillo::Blob zeros(write_size, 0);
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TEST_AND_RETURN_FALSE(underlying_extent_writer_->Write(zeros.data(),
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write_size));
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}
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return underlying_extent_writer_->End();
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}
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private:
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std::unique_ptr<ExtentWriter> underlying_extent_writer_;
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size_t block_size_{0};
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size_t bytes_written_mod_block_size_{0};
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};
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} // namespace chromeos_update_engine
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#endif // UPDATE_ENGINE_PAYLOAD_CONSUMER_EXTENT_WRITER_H_
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