Implement a proxy for Pepper FileIO.

ppapi/api/ppb_file_io.idl

 /* Copyright (c) 2011 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.
  */
 
 
 /**
  * This file defines the API to create a file i/o object.
  */
 
@@ skipping 81 matching lines @@
    * completion of Open().
    *
    * @return An int32_t containing an error code from <code>pp_errors.h</code>.
    */
   int32_t Open([in] PP_Resource file_io,
                [in] PP_Resource file_ref,
                [in] int32_t open_flags,
                [in] PP_CompletionCallback callback);
 
   /**
-   * Query() queries info about the file opened by this FileIO object. This
-   * function will fail if the FileIO object has not been opened.
+   * Query() queries info about the file opened by this FileIO object. The
+   * FileIO object must be opened, and there must be no other operations
+   * pending.
    *
    * @param[in] file_io A <code>PP_Resource</code> corresponding to a
    * FileIO.
    * @param[out] info The <code>PP_FileInfo</code> structure representing all
    * information about the file.
    * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
    * completion of Query().
    *
    * @return An int32_t containing an error code from <code>pp_errors.h</code>.
+   * PP_ERROR_FAILED will be returned if the file isn't opened, and
+   * PP_ERROR_INPROGRESS will be returned if there is another operation pending.
    */
   int32_t Query([in] PP_Resource file_io,
                 [out] PP_FileInfo info,
                 [in] PP_CompletionCallback callback);
 
   /**
    * Touch() Updates time stamps for the file opened by this FileIO object.
-   * This function will fail if the FileIO object has not been opened.
+   * This function will fail if the FileIO object has not been opened. The
+   * FileIO object must be opened, and there must be no other operations
+   * pending.
    *
    * @param[in] file_io A <code>PP_Resource</code> corresponding to a file
    * FileIO.
    * @param[in] last_access_time The last time the FileIO was accessed.
    * @param[in] last_modified_time The last time the FileIO was modified.
    * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
    * completion of Touch().
    *
    * @return An int32_t containing an error code from <code>pp_errors.h</code>.
+   * PP_ERROR_FAILED will be returned if the file isn't opened, and
+   * PP_ERROR_INPROGRESS will be returned if there is another operation pending.
    */
   int32_t Touch([in] PP_Resource file_io,
                 [in] PP_Time last_access_time,
                 [in] PP_Time last_modified_time,
                 [in] PP_CompletionCallback callback);
 
   /**
    * Read() reads from an offset in the file.  The size of the buffer must be
    * large enough to hold the specified number of bytes to read.  This function
    * might perform a partial read.
    *
    * @param[in] file_io A <code>PP_Resource</code> corresponding to a file
    * FileIO.
    * @param[in] offset The offset into the file.
    * @param[in] buffer The buffer to hold the specified number of bytes read.
    * @param[in] bytes_to_read The number of bytes to read from
    * <code>offset</code>.
    * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
    * completion of Read().
    *
    * @return An The number of bytes read an error code from
    * <code>pp_errors.h</code>. If the return value is 0, then end-of-file was
    * reached. It is valid to call Read() multiple times with a completion
-   * callback to queue up parallel reads from the file at different offsets.
+   * callback to queue up parallel reads from the file, but pending reads
+   * cannot be interleaved with other operations.
    */
   int32_t Read([in] PP_Resource file_io,
                [in] int64_t offset,
                [inout] str_t buffer,
                [in] int32_t bytes_to_read,
                [in] PP_CompletionCallback callback);
 
   /**
    * Write() writes to an offset in the file.  This function might perform a
    * partial write. The FileIO object must have been opened with write access.
    *
    * @param[in] file_io A <code>PP_Resource</code> corresponding to a file
    * FileIO.
    * @param[in] offset The offset into the file.
    * @param[in] buffer The buffer to hold the specified number of bytes read.
    * @param[in] bytes_to_write The number of bytes to write to
    * <code>offset</code>.
    * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
    * completion of Write().
    *
    * @return An The number of bytes written or an error code from
    * <code>pp_errors.h</code>. If the return value is 0, then end-of-file was
    * reached. It is valid to call Write() multiple times with a completion
-   * callback to queue up parallel writes to the file at different offsets.
+   * callback to queue up parallel writes to the file, but pending writes
+   * cannot be interleaved with other operations.
    */
   int32_t Write([in] PP_Resource file_io,
                 [in] int64_t offset,
                 [in] str_t buffer,
                 [in] int32_t bytes_to_write,
                 [in] PP_CompletionCallback callback);
   /**
    * SetLength() sets the length of the file.  If the file size is extended,
-   * then the extended area of the file is zero-filled.  The FileIO object must
-   * have been opened with write access.
+   * then the extended area of the file is zero-filled. The FileIO object must
+   * have been opened with write access and there must be no other operations
+   * pending.
    *
    * @param[in] file_io A <code>PP_Resource</code> corresponding to a file
    * FileIO.
    * @param[in] length The length of the file to be set.
    * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
    * completion of SetLength().
    *
    * @return An int32_t containing an error code from <code>pp_errors.h</code>.
+   * PP_ERROR_FAILED will be returned if the file isn't opened, and
+   * PP_ERROR_INPROGRESS will be returned if there is another operation pending.
    */
   int32_t SetLength([in] PP_Resource file_io,
                     [in] int64_t length,
                     [in] PP_CompletionCallback callback);
 
   /**
-   * Flush() flushes changes to disk.  This call can be very expensive!
+   * Flush() flushes changes to disk.  This call can be very expensive! The
+   * FileIO object must have been opened with write access and there must be no
+   * other operations pending.
    *
    * @param[in] file_io A <code>PP_Resource</code> corresponding to a file
    * FileIO.
    * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
    * completion of Flush().
    *
    * @return An int32_t containing an error code from <code>pp_errors.h</code>.
+   * PP_ERROR_FAILED will be returned if the file isn't opened, and
+   * PP_ERROR_INPROGRESS will be returned if there is another operation pending.
    */
   int32_t Flush([in] PP_Resource file_io,
                 [in] PP_CompletionCallback callback);
 
   /**
    * Close() cancels any IO that may be pending, and closes the FileIO object.
    * Any pending callbacks will still run, reporting
    * <code>PP_Error_Aborted</code> if pending IO was interrupted.  It is not
    * valid to call Open() again after a call to this method.
    * <strong>Note:</strong> If the FileIO object is destroyed, and it is still
    * open, then it will be implicitly closed, so you are not required to call
    * Close().
    *
    * @param[in] file_io A <code>PP_Resource</code> corresponding to a file
    * FileIO.
    */
   void Close([in] PP_Resource file_io);
 };