webkit/chromeos/fileapi/async_file_stream.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef WEBKIT_CHROMEOS_FILEAPI_ASYNC_FILE_STREAM_H_
   6 #define WEBKIT_CHROMEOS_FILEAPI_ASYNC_FILE_STREAM_H_
   7
   8 #include "base/callback.h"
   9 #include "base/platform_file.h"
  10
  11 namespace fileapi {
  12
  13 using base::PlatformFileError;
  14
  15 // This class is used for implementing Open() in FileUtilAsync. This class
  16 // is similar to net::FileStream, but supporting only the asynchronous
  17 // operations and not necessarily relying on PlatformFile.
  18 class AsyncFileStream {
  19  public:
  20   // Used for Read() and Write(). |result| is the return code of the
  21   // operation, and |length| is the length of data read or written.
  22   typedef base::Callback<void(PlatformFileError result,
  23                               int64 length)> ReadWriteCallback;
  24
  25   // Used for Seek(). |result| is the return code of the operation.
  26   typedef base::Callback<void(PlatformFileError)> SeekCallback;
  27
  28   virtual ~AsyncFileStream() {};
  29
  30   // Reads data from the current stream position. Up to |length| bytes
  31   // will be read from |buffer|. The memory pointed to by |buffer| must
  32   // remain valid until the callback is called. On success,
  33   // PLATFORM_FILE_OK is passed to |callback| with the number of bytes
  34   // read. On failure, an error code is passed instead.
  35   virtual void Read(char* buffer,
  36                     int64 length,
  37                     const ReadWriteCallback& callback) = 0;
  38
  39   // Writes data at the current stream position. Up to |length| bytes will
  40   // be written from |buffer|. The memory pointed to by |buffer| must
  41   // remain valid until the callback is called. On success,
  42   // PLATFORM_FILE_OK is passed to |callback| with the number of bytes
  43   // written. On failure, an error code is passed instead.
  44   virtual void Write(const char* buffer,
  45                      int64 length,
  46                      const ReadWriteCallback& callback) = 0;
  47
  48   // Moves the stream position. On success, PLATFORM_FILE_OK is passed to
  49   // |callback|. On error, an error code is passed instead.
  50   virtual void Seek(int64 offset,
  51                     const SeekCallback& callback) = 0;
  52 };
  53
  54 }  // namespace fileapi
  55
  56 #endif  // WEBKIT_CHROMEOS_FILEAPI_ASYNC_FILE_STREAM_H_