xref: /external/chromium_org/chrome/browser/chromeos/file_system_provider/fileapi/file_stream_reader.h

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_FILE_STREAM_READER_H_
#define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_FILE_STREAM_READER_H_

#include "base/basictypes.h"
#include "base/files/file_path.h"
#include "base/memory/weak_ptr.h"
#include "webkit/browser/blob/file_stream_reader.h"
#include "webkit/browser/fileapi/file_system_url.h"

namespace fileapi {
class AsyncFileUtil;
}  // namespace fileapi

namespace chromeos {
namespace file_system_provider {

class ProvidedFileSystemInterface;

// Implements a streamed file reader. It is lazily initialized by the first call
// to Read().
class FileStreamReader : public webkit_blob::FileStreamReader {
 public:
  typedef base::Callback<
      void(base::WeakPtr<ProvidedFileSystemInterface> file_system,
           const base::FilePath& file_path,
           int file_handle,
           base::File::Error result)> InitializeCompletedCallback;

  FileStreamReader(fileapi::FileSystemContext* context,
                   const fileapi::FileSystemURL& url,
                   int64 initial_offset,
                   const base::Time& expected_modification_time);

  virtual ~FileStreamReader();

  // webkit_blob::FileStreamReader overrides.
  virtual int Read(net::IOBuffer* buf,
                   int buf_len,
                   const net::CompletionCallback& callback) OVERRIDE;
  virtual int64 GetLength(
      const net::Int64CompletionCallback& callback) OVERRIDE;

 private:
  // Initializes the reader by opening the file. When completed with success,
  // runs the |pending_closure|. Otherwise, calls the |error_callback|.
  void Initialize(const base::Closure& pending_closure,
                  const net::Int64CompletionCallback& error_callback);

  // Called when initializing is completed with either a success or an error.
  void OnInitializeCompleted(
      const base::Closure& pending_closure,
      const net::Int64CompletionCallback& error_callback,
      base::WeakPtr<ProvidedFileSystemInterface> file_system,
      const base::FilePath& file_path,
      int file_handle,
      base::File::Error result);

  // Called when a file system provider returns chunk of read data. Note, that
  // this may be called multiple times per single Read() call, as long as
  // |has_more| is set to true. |result| is set to success only if reading is
  // successful, and the file has not changed while reading.
  void OnReadChunkReceived(const net::CompletionCallback& callback,
                           int chunk_length,
                           bool has_more,
                           base::File::Error result);

  // Called when fetching length of the file is completed with either a success
  // or an error.
  void OnGetMetadataForGetLengthReceived(
      const net::Int64CompletionCallback& callback,
      base::File::Error result,
      const base::File::Info& file_info);

  // Same as Read(), but called after initializing is completed.
  void ReadAfterInitialized(scoped_refptr<net::IOBuffer> buffer,
                            int buffer_length,
                            const net::CompletionCallback& callback);

  // Same as GetLength(), but called after initializing is completed.
  void GetLengthAfterInitialized(const net::Int64CompletionCallback& callback);

  fileapi::FileSystemURL url_;
  int64 current_offset_;
  int64 current_length_;
  base::Time expected_modification_time_;

  // Set during initialization (in case of a success).
  base::WeakPtr<ProvidedFileSystemInterface> file_system_;
  base::FilePath file_path_;
  int file_handle_;

  base::WeakPtrFactory<FileStreamReader> weak_ptr_factory_;
  DISALLOW_COPY_AND_ASSIGN(FileStreamReader);
};

}  // namespace file_system_provider
}  // namespace chromeos

#endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_FILE_STREAM_READER_H_