ppb_file_io.idl

/* 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.
 */


/**
 * This file defines the API to create a file i/o object.
 */

label Chrome {
  M14 = 1.0
};

/**
 * The PP_FileOpenFlags enum contains file open constants.
 */
[assert_size(4)]
 enum PP_FileOpenFlags {
  /** Requests read access to a file. */
  PP_FILEOPENFLAG_READ      = 1 << 0,

  /**
   * Requests write access to a file.  May be combined with
   * <code>PP_FILEOPENFLAG_READ</code> to request read and write access.
   */
  PP_FILEOPENFLAG_WRITE     = 1 << 1,

  /**
   * Requests that the file be created if it does not exist.  If the file
   * already exists, then this flag is ignored unless
   * <code>PP_FILEOPENFLAG_EXCLUSIVE</code> was also specified, in which case
   * FileIO::Open() will fail.
   */
  PP_FILEOPENFLAG_CREATE    = 1 << 2,

  /**
   * Requests that the file be truncated to length 0 if it exists and is a
   * regular file. <code>PP_FILEOPENFLAG_WRITE</code> must also be specified.
   */
   PP_FILEOPENFLAG_TRUNCATE  = 1 << 3,

  /**
   * Requests that the file is created when this flag is combined with
   * <code>PP_FILEOPENFLAG_CREATE</code>.  If this flag is specified, and the
   * file already exists, then the FileIO::Open() call will fail.
   */
  PP_FILEOPENFLAG_EXCLUSIVE = 1 << 4
};


/**
 * The <code>PPB_FileIO</code> struct is used to operate on a regular file
 * (PP_FileType_Regular).
 */
interface PPB_FileIO {
  /**
   * Create() creates a new FileIO object.
   *
   * @param[in] instance A <code>PP_Instance</code> identifying the instance
   * with the file.
   *
   * @return A <code>PP_Resource</code> corresponding to a FileIO if
   * successful or 0 if the module is invalid.
   */
  PP_Resource Create([in] PP_Instance instance);
  /**
   * IsFileIO() determines if the provided resource is a FileIO.
   *
   * @param[in] resource A <code>PP_Resource</code> corresponding to a FileIO.
   *
   * @return <code>PP_TRUE</code> if the resource is a
   * <code>PPB_FileIO</code>, <code>PP_FALSE</code> if the resource is
   * invalid or some type other than <code>PPB_FileIO</code>.
   */
  PP_Bool IsFileIO([in] PP_Resource resource);

  /**
   * Open() opens the specified regular file for I/O according to the given
   * open flags, which is a bit-mask of the <code>PP_FileOpenFlags</code>
   * values. Upon success, the corresponding file is classified as "in use"
   * by this FileIO object until such time as the FileIO object is closed
   * or destroyed.
   *
   * @param[in] file_io A <code>PP_Resource</code> corresponding to a
   * FileIO.
   * @param[in] file_ref A <code>PP_Resource</code> corresponding to a file
   * reference.
   * @param[in] open_flags A bit-mask of the <code>PP_FileOpenFlags</code>
   * values.
   * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
   * 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. 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. 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 The number of bytes read 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 Read() multiple times with a completion
   * 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 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, 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 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! 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);
};