Add getFileSize support to chromium...

chrome/browser/renderer_host/file_system_accessor.h

+// Copyright (c) 2006-2009 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.
+//
+// FileSystemAccessor provides functions so consumers can do file access
+// asynchronously. It would PostTask to FILE thread to access file info, then on
+// completion PostTask back to the caller thread and pass the result back.
+// Here is an example on how to use it to get file size:
+//   1. Define a callback function so FileSystemAccessor could run it after the
+//      task has been completed:
+//      void Foo::GetFileSizeCallback(int64 result, void* param) {
+//      }
+//   2. Call static function FileSystemAccessor::RequestFileSize, provide file
+//      path, param (any object you want to pass back to the callback function)
+//      and callback:
+//      FileSystemAccessor::RequestFileSize(
+//          path,
+//          param,
+//          NewCallback(this, &Foo::GetFileSizeCallback));
+//   3. FileSystemAceessor would PostTask to FILE thread to get file size, then
+//      on completion it would PostTask back to the current thread and run
+//      Foo::GetFileSizeCallback.
+//
+
+#ifndef CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_
+#define CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_
+
+#include "base/file_path.h"
+#include "base/scoped_ptr.h"
+#include "base/ref_counted.h"
+#include "base/task.h"
+
+class MessageLoop;
+
+class FileSystemAccessor
+    : public base::RefCountedThreadSafe<FileSystemAccessor> {
+ public:
+  typedef Callback2<int64, void*>::Type FileSizeCallback;
+
+  virtual ~FileSystemAccessor();
+
+  // Request to get file size.
+  //
+  // param is an object that is owned by the caller and needs to pass back to
+  // the caller by FileSystemAccessor through the callback function.
+  // It can be set to NULL if no object needs to pass back.
+  //
+  // FileSizeCallback function is defined as:
+  // void f(int64 result, void* param);
+  // Variable result has the file size. If the file does not exist or there is
+  // error accessing the file, result is set to -1. If the given path is a
+  // directory, result is set to 0.
+  static void RequestFileSize(const FilePath& path,
+                              void* param,
+                              FileSizeCallback* callback);
+
+ private:
+  FileSystemAccessor(void* param, FileSizeCallback* callback);
+
+  // Get file size on the worker thread and pass result back to the caller
+  // thread.
+  void GetFileSize(const FilePath& path);
+
+  // Getting file size completed, callback to reply message.
+  void GetFileSizeCompleted(int64 result);
+
+  MessageLoop* caller_loop_;
+  void* param_;
+  scoped_ptr<FileSizeCallback> callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(FileSystemAccessor);
+};
+
+#endif  // CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_