ppb_file_io.h

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/* 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.
 */

/* From ppb_file_io.idl modified Tue Oct 22 15:09:47 2013. */

#ifndef PPAPI_C_PPB_FILE_IO_H_
#define PPAPI_C_PPB_FILE_IO_H_

#include "ppapi/c/pp_array_output.h"
#include "ppapi/c/pp_bool.h"
#include "ppapi/c/pp_completion_callback.h"
#include "ppapi/c/pp_file_info.h"
#include "ppapi/c/pp_instance.h"
#include "ppapi/c/pp_macros.h"
#include "ppapi/c/pp_resource.h"
#include "ppapi/c/pp_stdint.h"
#include "ppapi/c/pp_time.h"

#define PPB_FILEIO_INTERFACE_1_0 "PPB_FileIO;1.0"
#define PPB_FILEIO_INTERFACE_1_1 "PPB_FileIO;1.1"
#define PPB_FILEIO_INTERFACE PPB_FILEIO_INTERFACE_1_1

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


/**
 * @addtogroup Enums
 * @{
 */
/**
 * The PP_FileOpenFlags enum contains file open constants.
 */
typedef enum {
  /** 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,
  /**
   * Requests write access to a file, but writes will always occur at the end of
   * the file. Mututally exclusive with <code>PP_FILEOPENFLAG_WRITE</code>.
   *
   * This is only supported in version 1.2 (Chrome 29) and later.
   */
  PP_FILEOPENFLAG_APPEND = 1 << 5
} PP_FileOpenFlags;
PP_COMPILE_ASSERT_SIZE_IN_BYTES(PP_FileOpenFlags, 4);
/**
 * @}
 */

/**
 * @addtogroup Interfaces
 * @{
 */
/**
 * The <code>PPB_FileIO</code> struct is used to operate on a regular file
 * (PP_FileType_Regular).
 */
struct PPB_FileIO_1_1 {
  /**
   * 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)(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)(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)(PP_Resource file_io,
                  PP_Resource file_ref,
                  int32_t open_flags,
                  struct 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(). <code>info</code> must remain valid until after the
   * callback runs. If you pass a blocking callback, <code>info</code> must
   * remain valid until after Query() returns.
   *
   * @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)(PP_Resource file_io,
                   struct PP_FileInfo* info,
                   struct 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)(PP_Resource file_io,
                   PP_Time last_access_time,
                   PP_Time last_modified_time,
                   struct 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, meaning all the requested bytes
   * might not be returned, even if the end of the file has not been reached.
   * The FileIO object must have been opened with read access.
   *
   * ReadToArray() is preferred to Read() when doing asynchronous operations.
   *
   * @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(). <code>buffer</code> must remain valid until after
   * the callback runs. If you pass a blocking callback, <code>buffer</code>
   * must remain valid until after Read() returns.
   *
   * @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)(PP_Resource file_io,
                  int64_t offset,
                  char* buffer,
                  int32_t bytes_to_read,
                  struct 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)(PP_Resource file_io,
                   int64_t offset,
                   const char* buffer,
                   int32_t bytes_to_write,
                   struct 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)(PP_Resource file_io,
                       int64_t length,
                       struct 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)(PP_Resource file_io, struct 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)(PP_Resource file_io);
  /**
   * ReadToArray() reads from an offset in the file.  A PP_ArrayOutput must be
   * provided so that output will be stored in its allocated buffer.  This
   * function might perform a partial read. The FileIO object must have been
   * opened with read 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] max_read_length The maximum number of bytes to read from
   * <code>offset</code>.
   * @param[in] output A <code>PP_ArrayOutput</code> to hold the output data.
   * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
   * completion of ReadToArray().
   *
   * @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 ReadToArray() 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 (*ReadToArray)(PP_Resource file_io,
                         int64_t offset,
                         int32_t max_read_length,
                         struct PP_ArrayOutput* output,
                         struct PP_CompletionCallback callback);
};

typedef struct PPB_FileIO_1_1 PPB_FileIO;

struct PPB_FileIO_1_0 {
  PP_Resource (*Create)(PP_Instance instance);
  PP_Bool (*IsFileIO)(PP_Resource resource);
  int32_t (*Open)(PP_Resource file_io,
                  PP_Resource file_ref,
                  int32_t open_flags,
                  struct PP_CompletionCallback callback);
  int32_t (*Query)(PP_Resource file_io,
                   struct PP_FileInfo* info,
                   struct PP_CompletionCallback callback);
  int32_t (*Touch)(PP_Resource file_io,
                   PP_Time last_access_time,
                   PP_Time last_modified_time,
                   struct PP_CompletionCallback callback);
  int32_t (*Read)(PP_Resource file_io,
                  int64_t offset,
                  char* buffer,
                  int32_t bytes_to_read,
                  struct PP_CompletionCallback callback);
  int32_t (*Write)(PP_Resource file_io,
                   int64_t offset,
                   const char* buffer,
                   int32_t bytes_to_write,
                   struct PP_CompletionCallback callback);
  int32_t (*SetLength)(PP_Resource file_io,
                       int64_t length,
                       struct PP_CompletionCallback callback);
  int32_t (*Flush)(PP_Resource file_io, struct PP_CompletionCallback callback);
  void (*Close)(PP_Resource file_io);
};
/**
 * @}
 */

#endif  /* PPAPI_C_PPB_FILE_IO_H_ */