fileapi: FileWriter and LocalFileWriter.

webkit/fileapi/local_file_writer.h

+// Copyright (c) 2012 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 WEBKIT_FILEAPI_LOCAL_FILE_WRITER_H_
+#define WEBKIT_FILEAPI_LOCAL_FILE_WRITER_H_
+#pragma once
+
+#include <utility>
+
+#include "base/compiler_specific.h"
+#include "base/callback.h"
+#include "base/file_path.h"
+#include "base/platform_file.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "webkit/fileapi/file_writer.h"
+
+namespace net {
+class FileStream;
+}
+
+namespace fileapi {
+
+// This class is a thin wrapper around net::FileStream for writing local files.
+class LocalFileWriter : public FileWriter {
+ public:
+  // Create a writer for the existing file in the path |file_path| starting from
+  // |initial_offset|.
+  LocalFileWriter(const FilePath& file_path, int64 initial_offset);
+  virtual ~LocalFileWriter();
+
+  // FileWriter overrides.
+  virtual int Write(net::IOBuffer* buf, int buf_len,
+                    const net::CompletionCallback& callback) OVERRIDE;
+  virtual int Cancel(const net::CompletionCallback& callback) OVERRIDE;
+
+ private:
+  // Opens |file_path_| and if it succeeds, proceeds to InitiateSeek().
+  // If failed, the error code is returned by calling |error_callback|.
+  int InitiateOpen(const net::CompletionCallback& error_callback,
+                   const base::Closure& main_operation);
+  void DidOpen(const net::CompletionCallback& error_callback,
+               const base::Closure& main_operation,
+               int result);
+
+  // Seeks to |initial_offset_| and proceeds to |main_operation| if it succeeds.
+  // If failed, the error code is returned by calling |error_callback|.
+  void InitiateSeek(const net::CompletionCallback& error_callback,
+                    const base::Closure& main_operation);
+  void DidSeek(const net::CompletionCallback& error_callback,
+               const base::Closure& main_operation,
+               int64 result);
+
+  // Passed as the |main_operation| of InitiateOpen() function.
+  void ReadyToWrite(net::IOBuffer* buf, int buf_len,
+                    const net::CompletionCallback& callback);
+
+  // Writes asynchronously to the file.
+  int InitiateWrite(net::IOBuffer* buf, int buf_len,
+                    const net::CompletionCallback& callback);
+  void DidWrite(const net::CompletionCallback& callback, int result);
+
+  // Stops the in-flight operation and calls |cancel_callback_| if it has been
+  // set by Cancel() for the current operation.
+  bool CancelIfRequested();
+
+  // Initialization parameters.
+  const FilePath file_path_;
+  const int64 initial_offset_;
+
+  // Current states of the operation.
+  bool has_pending_operation_;
+  scoped_ptr<net::FileStream> stream_impl_;
+  net::CompletionCallback cancel_callback_;
+
+  base::WeakPtrFactory<LocalFileWriter> weak_factory_;
+  DISALLOW_COPY_AND_ASSIGN(LocalFileWriter);
+};
+
+}  // namespace fileapi
+
+#endif  // WEBKIT_FILEAPI_LOCAL_FILE_WRITER_H_