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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_FILE_WRITER_H_
#define UPDATE_ENGINE_FILE_WRITER_H_
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <base/logging.h>
#include "update_engine/error_code.h"
#include "update_engine/utils.h"
// FileWriter is a class that is used to (synchronously, for now) write to
// a file. This file is a thin wrapper around open/write/close system calls,
// but provides and interface that can be customized by subclasses that wish
// to filter the data.
namespace chromeos_update_engine {
class FileWriter {
public:
FileWriter() {}
virtual ~FileWriter() {}
// Wrapper around write. Returns true if all requested bytes
// were written, or false on any error, regardless of progress.
virtual bool Write(const void* bytes, size_t count) = 0;
// Same as the Write method above but returns a detailed |error| code
// in addition if the returned value is false. By default this method
// returns kActionExitDownloadWriteError as the error code, but subclasses
// can override if they wish to return more specific error codes.
virtual bool Write(const void* bytes,
size_t count,
ErrorCode* error) {
*error = ErrorCode::kDownloadWriteError;
return Write(bytes, count);
}
// Wrapper around close. Returns 0 on success or -errno on error.
virtual int Close() = 0;
private:
DISALLOW_COPY_AND_ASSIGN(FileWriter);
};
// Direct file writer is probably the simplest FileWriter implementation.
// It calls the system calls directly.
class DirectFileWriter : public FileWriter {
public:
DirectFileWriter() = default;
// FileWriter overrides.
bool Write(const void* bytes, size_t count) override;
int Close() override;
// Wrapper around open. Returns 0 on success or -errno on error.
int Open(const char* path, int flags, mode_t mode);
int fd() const { return fd_; }
private:
int fd_{-1};
DISALLOW_COPY_AND_ASSIGN(DirectFileWriter);
};
class ScopedFileWriterCloser {
public:
explicit ScopedFileWriterCloser(FileWriter* writer) : writer_(writer) {}
~ScopedFileWriterCloser() {
int err = writer_->Close();
if (err)
LOG(ERROR) << "FileWriter::Close failed: "
<< utils::ErrnoNumberAsString(-err);
}
private:
FileWriter* writer_;
DISALLOW_COPY_AND_ASSIGN(ScopedFileWriterCloser);
};
} // namespace chromeos_update_engine
#endif // UPDATE_ENGINE_FILE_WRITER_H_