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//
// Copyright (C) 2009 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.
//
#ifndef UPDATE_ENGINE_EXTENT_WRITER_H_
#define UPDATE_ENGINE_EXTENT_WRITER_H_
#include <vector>
#include <base/logging.h>
#include <chromeos/secure_blob.h>
#include "update_engine/file_descriptor.h"
#include "update_engine/update_metadata.pb.h"
#include "update_engine/utils.h"
// ExtentWriter is an abstract class which synchronously writes to a given
// file descriptor at the extents given.
namespace chromeos_update_engine {
class ExtentWriter {
public:
ExtentWriter() : end_called_(false) {}
virtual ~ExtentWriter() {
LOG_IF(ERROR, !end_called_) << "End() not called on ExtentWriter.";
}
// Returns true on success.
virtual bool Init(FileDescriptorPtr fd,
const std::vector<Extent>& extents,
uint32_t block_size) = 0;
// Returns true on success.
virtual bool Write(const void* bytes, size_t count) = 0;
// Should be called when all writing is complete. Returns true on success.
// The fd is not closed. Caller is responsible for closing it.
bool End() {
end_called_ = true;
return EndImpl();
}
virtual bool EndImpl() = 0;
private:
bool end_called_;
};
// DirectExtentWriter is probably the simplest ExtentWriter implementation.
// It writes the data directly into the extents.
class DirectExtentWriter : public ExtentWriter {
public:
DirectExtentWriter()
: fd_(nullptr),
block_size_(0),
extent_bytes_written_(0),
next_extent_index_(0) {}
~DirectExtentWriter() {}
bool Init(FileDescriptorPtr fd,
const std::vector<Extent>& extents,
uint32_t block_size) {
fd_ = fd;
block_size_ = block_size;
extents_ = extents;
return true;
}
bool Write(const void* bytes, size_t count);
bool EndImpl() {
return true;
}
private:
FileDescriptorPtr fd_;
size_t block_size_;
// Bytes written into next_extent_index_ thus far
uint64_t extent_bytes_written_;
std::vector<Extent> extents_;
// The next call to write should correspond to extents_[next_extent_index_]
std::vector<Extent>::size_type next_extent_index_;
};
// Takes an underlying ExtentWriter to which all operations are delegated.
// When End() is called, ZeroPadExtentWriter ensures that the total number
// of bytes written is a multiple of block_size_. If not, it writes zeros
// to pad as needed.
class ZeroPadExtentWriter : public ExtentWriter {
public:
explicit ZeroPadExtentWriter(ExtentWriter* underlying_extent_writer)
: underlying_extent_writer_(underlying_extent_writer),
block_size_(0),
bytes_written_mod_block_size_(0) {}
~ZeroPadExtentWriter() {}
bool Init(FileDescriptorPtr fd,
const std::vector<Extent>& extents,
uint32_t block_size) {
block_size_ = block_size;
return underlying_extent_writer_->Init(fd, extents, block_size);
}
bool Write(const void* bytes, size_t count) {
if (underlying_extent_writer_->Write(bytes, count)) {
bytes_written_mod_block_size_ += count;
bytes_written_mod_block_size_ %= block_size_;
return true;
}
return false;
}
bool EndImpl() {
if (bytes_written_mod_block_size_) {
const size_t write_size = block_size_ - bytes_written_mod_block_size_;
chromeos::Blob zeros(write_size, 0);
TEST_AND_RETURN_FALSE(underlying_extent_writer_->Write(zeros.data(),
write_size));
}
return underlying_extent_writer_->End();
}
private:
ExtentWriter* underlying_extent_writer_; // The underlying ExtentWriter.
size_t block_size_;
size_t bytes_written_mod_block_size_;
};
} // namespace chromeos_update_engine
#endif // UPDATE_ENGINE_EXTENT_WRITER_H_