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