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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_WEB_PACKAGE_SHARED_FILE_H_
#define COMPONENTS_WEB_PACKAGE_SHARED_FILE_H_
#include <memory>
#include "base/callback.h"
#include "base/files/file.h"
#include "base/memory/ref_counted.h"
#include "base/task/sequenced_task_runner.h"
#include "mojo/public/cpp/system/data_pipe_producer.h"
namespace web_package {
// A simple wrapper class to share a single `base::File` instance among multiple
// `SharedFile::SharedFileDataSource` instances.
class SharedFile final : public base::RefCountedThreadSafe<SharedFile> {
public:
// The file passed to this method must have been opened for reading.
explicit SharedFile(std::unique_ptr<base::File> file);
SharedFile(const SharedFile&) = delete;
SharedFile& operator=(const SharedFile&) = delete;
// Duplicate the underlying `base::File`. This is only needed for APIs that
// require a `base::File` and cannot use a `SharedFile`.
void DuplicateFile(base::OnceCallback<void(base::File)> callback);
// Allow access to the underlying instance of `base::File`.
base::File* operator->();
class SharedFileDataSource final : public mojo::DataPipeProducer::DataSource {
public:
SharedFileDataSource(scoped_refptr<SharedFile> file,
uint64_t offset,
uint64_t length);
SharedFileDataSource(const SharedFileDataSource&) = delete;
SharedFileDataSource& operator=(const SharedFileDataSource&) = delete;
~SharedFileDataSource() override;
private:
// Implements `mojo::DataPipeProducer::DataSource`. The following methods
// are called on a blockable sequenced task runner.
uint64_t GetLength() const override;
ReadResult Read(uint64_t offset, base::span<char> buffer) override;
scoped_refptr<SharedFile> file_;
MojoResult error_;
const uint64_t offset_;
const uint64_t length_;
};
std::unique_ptr<SharedFileDataSource> CreateDataSource(uint64_t offset,
uint64_t length);
private:
friend class base::RefCountedThreadSafe<SharedFile>;
~SharedFile();
scoped_refptr<base::SequencedTaskRunner> task_runner_;
std::unique_ptr<base::File> file_;
};
} // namespace web_package
#endif // COMPONENTS_WEB_PACKAGE_SHARED_FILE_H_
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