gio/gfileinputstream.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright (C) 2006-2007 Red Hat, Inc.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General
  16  * Public License along with this library; if not, write to the
  17  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  18  * Boston, MA 02111-1307, USA.
  19  *
  20  * Author: Alexander Larsson <alexl@redhat.com>
  21  */
  22
  23 #include <config.h>
  24
  25 #include <glib.h>
  26 #include <gfileinputstream.h>
  27 #include <gseekable.h>
  28 #include "gsimpleasyncresult.h"
  29 #include "glibintl.h"
  30
  31 /**
  32  * SECTION:gfileinputstream
  33  * @short_description: file input streaming operations
  34  * @see_also: #GInputStream, #GDataInputStream, #GSeekable.
  35  *
  36  *
  37  *
  38  **/
  39
  40 static void       g_file_input_stream_seekable_iface_init    (GSeekableIface       *iface);
  41 static goffset    g_file_input_stream_seekable_tell          (GSeekable            *seekable);
  42 static gboolean   g_file_input_stream_seekable_can_seek      (GSeekable            *seekable);
  43 static gboolean   g_file_input_stream_seekable_seek          (GSeekable            *seekable,
  44                                                               goffset               offset,
  45                                                               GSeekType             type,
  46                                                               GCancellable         *cancellable,
  47                                                               GError              **error);
  48 static gboolean   g_file_input_stream_seekable_can_truncate  (GSeekable            *seekable);
  49 static gboolean   g_file_input_stream_seekable_truncate      (GSeekable            *seekable,
  50                                                               goffset               offset,
  51                                                               GCancellable         *cancellable,
  52                                                               GError              **error);
  53 static void       g_file_input_stream_real_query_info_async  (GFileInputStream     *stream,
  54                                                               char                 *attributes,
  55                                                               int                   io_priority,
  56                                                               GCancellable         *cancellable,
  57                                                               GAsyncReadyCallback   callback,
  58                                                               gpointer              user_data);
  59 static GFileInfo *g_file_input_stream_real_query_info_finish (GFileInputStream     *stream,
  60                                                               GAsyncResult         *result,
  61                                                               GError              **error);
  62
  63
  64 G_DEFINE_TYPE_WITH_CODE (GFileInputStream, g_file_input_stream, G_TYPE_INPUT_STREAM,
  65                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  66                                                 g_file_input_stream_seekable_iface_init))
  67
  68 struct _GFileInputStreamPrivate {
  69   GAsyncReadyCallback outstanding_callback;
  70 };
  71
  72 static void
  73 g_file_input_stream_class_init (GFileInputStreamClass *klass)
  74 {
  75   g_type_class_add_private (klass, sizeof (GFileInputStreamPrivate));
  76
  77   klass->query_info_async = g_file_input_stream_real_query_info_async;
  78   klass->query_info_finish = g_file_input_stream_real_query_info_finish;
  79 }
  80
  81 static void
  82 g_file_input_stream_seekable_iface_init (GSeekableIface *iface)
  83 {
  84   iface->tell = g_file_input_stream_seekable_tell;
  85   iface->can_seek = g_file_input_stream_seekable_can_seek;
  86   iface->seek = g_file_input_stream_seekable_seek;
  87   iface->can_truncate = g_file_input_stream_seekable_can_truncate;
  88   iface->truncate = g_file_input_stream_seekable_truncate;
  89 }
  90
  91 static void
  92 g_file_input_stream_init (GFileInputStream *stream)
  93 {
  94   stream->priv = G_TYPE_INSTANCE_GET_PRIVATE (stream,
  95                                               G_TYPE_FILE_INPUT_STREAM,
  96                                               GFileInputStreamPrivate);
  97 }
  98
  99 /**
 100  * g_file_input_stream_query_info:
 101  * @stream: a #GFileInputStream.
 102  * @attributes: a file attribute query string.
 103  * @cancellable: optional #GCancellable object, %NULL to ignore.
 104  * @error: a #GError location to store the error occuring, or %NULL to
 105  * ignore.
 106  *
 107  * Queries a file input stream the given @attributes.his function blocks while querying
 108  * the stream. For the asynchronous (non-blocking) version of this function, see
 109  * g_file_input_stream_query_info_async(). While the stream is blocked,
 110  * the stream will set the pending flag internally, and any other operations on the
 111  * stream will fail with %G_IO_ERROR_PENDING.
 112  *
 113  * Returns: a #GFileInfo, or %NULL on error.
 114  **/
 115 GFileInfo *
 116 g_file_input_stream_query_info (GFileInputStream     *stream,
 117                                    char                 *attributes,
 118                                    GCancellable         *cancellable,
 119                                    GError              **error)
 120 {
 121   GFileInputStreamClass *class;
 122   GInputStream *input_stream;
 123   GFileInfo *info;
 124
 125   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
 126
 127   input_stream = G_INPUT_STREAM (stream);
 128
 129   if (g_input_stream_is_closed (input_stream))
 130     {
 131       g_set_error (error, G_IO_ERROR, G_IO_ERROR_CLOSED,
 132                    _("Stream is already closed"));
 133       return NULL;
 134     }
 135
 136   if (g_input_stream_has_pending (input_stream))
 137     {
 138       g_set_error (error, G_IO_ERROR, G_IO_ERROR_PENDING,
 139                    _("Stream has outstanding operation"));
 140       return NULL;
 141     }
 142
 143   info = NULL;
 144
 145   g_input_stream_set_pending (input_stream, TRUE);
 146
 147   if (cancellable)
 148     g_push_current_cancellable (cancellable);
 149
 150   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 151   if (class->query_info)
 152     info = class->query_info (stream, attributes, cancellable, error);
 153   else
 154     g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 155                  _("Stream doesn't support query_info"));
 156
 157   if (cancellable)
 158     g_pop_current_cancellable (cancellable);
 159
 160   g_input_stream_set_pending (input_stream, FALSE);
 161
 162   return info;
 163 }
 164
 165 static void
 166 async_ready_callback_wrapper (GObject *source_object,
 167                               GAsyncResult *res,
 168                               gpointer      user_data)
 169 {
 170   GFileInputStream *stream = G_FILE_INPUT_STREAM (source_object);
 171
 172   g_input_stream_set_pending (G_INPUT_STREAM (stream), FALSE);
 173   if (stream->priv->outstanding_callback)
 174     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 175   g_object_unref (stream);
 176 }
 177
 178 /**
 179  * g_file_input_stream_query_info_async:
 180  * @stream: a #GFileInputStream.
 181  * @attributes: a file attribute query string.
 182  * @io_priority: the i/o priority of the request.
 183  * @cancellable: optional #GCancellable object, %NULL to ignore.
 184  * @callback: callback to call when the request is satisfied
 185  * @user_data: the data to pass to callback function
 186  *
 187  * Queries the stream information asynchronously. For the synchronous version
 188  * of this function, see g_file_input_stream_query_info().
 189  *
 190  * If @cancellable is not %NULL, then the operation can be cancelled by
 191  * triggering the cancellable object from another thread. If the operation
 192  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set
 193  *
 194  **/
 195 void
 196 g_file_input_stream_query_info_async (GFileInputStream     *stream,
 197                                          char                 *attributes,
 198                                          int                   io_priority,
 199                                          GCancellable         *cancellable,
 200                                          GAsyncReadyCallback   callback,
 201                                          gpointer              user_data)
 202 {
 203   GFileInputStreamClass *klass;
 204   GInputStream *input_stream;
 205
 206   g_return_if_fail (G_IS_FILE_INPUT_STREAM (stream));
 207
 208   input_stream = G_INPUT_STREAM (stream);
 209
 210   if (g_input_stream_is_closed (input_stream))
 211     {
 212       g_simple_async_report_error_in_idle (G_OBJECT (stream),
 213                                            callback,
 214                                            user_data,
 215                                            G_IO_ERROR, G_IO_ERROR_CLOSED,
 216                                            _("Stream is already closed"));
 217       return;
 218     }
 219
 220   if (g_input_stream_has_pending (input_stream))
 221     {
 222       g_simple_async_report_error_in_idle (G_OBJECT (stream),
 223                                            callback,
 224                                            user_data,
 225                                            G_IO_ERROR, G_IO_ERROR_PENDING,
 226                                            _("Stream has outstanding operation"));
 227       return;
 228     }
 229
 230   klass = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 231
 232   g_input_stream_set_pending (input_stream, TRUE);
 233   stream->priv->outstanding_callback = callback;
 234   g_object_ref (stream);
 235   klass->query_info_async (stream, attributes, io_priority, cancellable,
 236                               async_ready_callback_wrapper, user_data);
 237 }
 238
 239 /**
 240  * g_file_input_stream_query_info_finish:
 241  * @stream: a #GFileInputStream.
 242  * @result: a #GAsyncResult.
 243  * @error: a #GError location to store the error occuring, or %NULL to
 244  * ignore.
 245  *
 246  * Finishes an asynchronous info query operation.
 247  *
 248  * Returns: #GFileInfo.
 249  **/
 250 GFileInfo *
 251 g_file_input_stream_query_info_finish (GFileInputStream     *stream,
 252                                           GAsyncResult         *result,
 253                                           GError              **error)
 254 {
 255   GSimpleAsyncResult *simple;
 256   GFileInputStreamClass *class;
 257
 258   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
 259   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 260
 261   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 262     {
 263       simple = G_SIMPLE_ASYNC_RESULT (result);
 264       if (g_simple_async_result_propagate_error (simple, error))
 265         return NULL;
 266     }
 267
 268   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 269   return class->query_info_finish (stream, result, error);
 270 }
 271
 272 /**
 273  * g_file_input_stream_tell:
 274  * @stream: a #GFileInputStream.
 275  *
 276  * Gets the current position in the stream.
 277  *
 278  * Returns: a #goffset with the position in the stream.
 279  **/
 280 goffset
 281 g_file_input_stream_tell (GFileInputStream  *stream)
 282 {
 283   GFileInputStreamClass *class;
 284   goffset offset;
 285
 286   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), 0);
 287
 288   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 289
 290   offset = 0;
 291   if (class->tell)
 292     offset = class->tell (stream);
 293
 294   return offset;
 295 }
 296
 297 static goffset
 298 g_file_input_stream_seekable_tell (GSeekable *seekable)
 299 {
 300   return g_file_input_stream_tell (G_FILE_INPUT_STREAM (seekable));
 301 }
 302
 303 /**
 304  * g_file_input_stream_can_seek:
 305  * @stream: a #GFileInputStream.
 306  *
 307  * Checks if a file input stream can be seeked.
 308  *
 309  * Returns: %TRUE if stream can be seeked. %FALSE otherwise.
 310  **/
 311 gboolean
 312 g_file_input_stream_can_seek (GFileInputStream  *stream)
 313 {
 314   GFileInputStreamClass *class;
 315   gboolean can_seek;
 316
 317   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 318
 319   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 320
 321   can_seek = FALSE;
 322   if (class->seek)
 323     {
 324       can_seek = TRUE;
 325       if (class->can_seek)
 326         can_seek = class->can_seek (stream);
 327     }
 328
 329   return can_seek;
 330 }
 331
 332 static gboolean
 333 g_file_input_stream_seekable_can_seek (GSeekable *seekable)
 334 {
 335   return g_file_input_stream_can_seek (G_FILE_INPUT_STREAM (seekable));
 336 }
 337
 338 /**
 339  * g_file_input_stream_seek:
 340  * @stream: a #GFileInputStream.
 341  * @offset: a #goffset to seek.
 342  * @type: a #GSeekType.
 343  * @cancellable: optional #GCancellable object, %NULL to ignore.
 344  * @error: a #GError location to store the error occuring, or %NULL to
 345  * ignore.
 346  *
 347  * Seeks in the file input stream.
 348  *
 349  * If @cancellable is not %NULL, then the operation can be cancelled by
 350  * triggering the cancellable object from another thread. If the operation
 351  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set.
 352  *
 353  * Returns: %TRUE if the stream was successfully seeked to the position.
 354  * %FALSE on error.
 355  **/
 356 gboolean
 357 g_file_input_stream_seek (GFileInputStream  *stream,
 358                           goffset            offset,
 359                           GSeekType          type,
 360                           GCancellable      *cancellable,
 361                           GError           **error)
 362 {
 363   GFileInputStreamClass *class;
 364   GInputStream *input_stream;
 365   gboolean res;
 366
 367   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 368
 369   input_stream = G_INPUT_STREAM (stream);
 370   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 371
 372   if (g_input_stream_is_closed (input_stream))
 373     {
 374       g_set_error (error, G_IO_ERROR, G_IO_ERROR_CLOSED,
 375                    _("Stream is already closed"));
 376       return FALSE;
 377     }
 378
 379   if (g_input_stream_has_pending (input_stream))
 380     {
 381       g_set_error (error, G_IO_ERROR, G_IO_ERROR_PENDING,
 382                    _("Stream has outstanding operation"));
 383       return FALSE;
 384     }
 385
 386   if (!class->seek)
 387     {
 388       g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 389                    _("Seek not supported on stream"));
 390       return FALSE;
 391     }
 392
 393   g_input_stream_set_pending (input_stream, TRUE);
 394
 395   if (cancellable)
 396     g_push_current_cancellable (cancellable);
 397
 398   res = class->seek (stream, offset, type, cancellable, error);
 399
 400   if (cancellable)
 401     g_pop_current_cancellable (cancellable);
 402
 403   g_input_stream_set_pending (input_stream, FALSE);
 404
 405   return res;
 406 }
 407
 408 static gboolean
 409 g_file_input_stream_seekable_seek (GSeekable  *seekable,
 410                                    goffset     offset,
 411                                    GSeekType   type,
 412                                    GCancellable  *cancellable,
 413                                    GError    **error)
 414 {
 415   return g_file_input_stream_seek (G_FILE_INPUT_STREAM (seekable),
 416                                    offset, type, cancellable, error);
 417 }
 418
 419 static gboolean
 420 g_file_input_stream_seekable_can_truncate (GSeekable  *seekable)
 421 {
 422   return FALSE;
 423 }
 424
 425 static gboolean
 426 g_file_input_stream_seekable_truncate (GSeekable  *seekable,
 427                                        goffset     offset,
 428                                        GCancellable  *cancellable,
 429                                        GError    **error)
 430 {
 431   g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 432                _("Truncate not allowed on input stream"));
 433   return FALSE;
 434 }
 435
 436 /********************************************
 437  *   Default implementation of async ops    *
 438  ********************************************/
 439
 440 typedef struct {
 441   char *attributes;
 442   GFileInfo *info;
 443 } QueryInfoAsyncData;
 444
 445 static void
 446 query_info_data_free (QueryInfoAsyncData *data)
 447 {
 448   if (data->info)
 449     g_object_unref (data->info);
 450   g_free (data->attributes);
 451   g_free (data);
 452 }
 453
 454 static void
 455 query_info_async_thread (GSimpleAsyncResult *res,
 456                        GObject *object,
 457                        GCancellable *cancellable)
 458 {
 459   GFileInputStreamClass *class;
 460   GError *error = NULL;
 461   QueryInfoAsyncData *data;
 462   GFileInfo *info;
 463
 464   data = g_simple_async_result_get_op_res_gpointer (res);
 465
 466   info = NULL;
 467
 468   class = G_FILE_INPUT_STREAM_GET_CLASS (object);
 469   if (class->query_info)
 470     info = class->query_info (G_FILE_INPUT_STREAM (object), data->attributes, cancellable, &error);
 471   else
 472     g_set_error (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 473                  _("Stream doesn't support query_info"));
 474
 475   if (info == NULL)
 476     {
 477       g_simple_async_result_set_from_error (res, error);
 478       g_error_free (error);
 479     }
 480   else
 481     data->info = info;
 482 }
 483
 484 static void
 485 g_file_input_stream_real_query_info_async (GFileInputStream     *stream,
 486                                               char                 *attributes,
 487                                               int                   io_priority,
 488                                               GCancellable         *cancellable,
 489                                               GAsyncReadyCallback   callback,
 490                                               gpointer              user_data)
 491 {
 492   GSimpleAsyncResult *res;
 493   QueryInfoAsyncData *data;
 494
 495   data = g_new0 (QueryInfoAsyncData, 1);
 496   data->attributes = g_strdup (attributes);
 497
 498   res = g_simple_async_result_new (G_OBJECT (stream), callback, user_data, g_file_input_stream_real_query_info_async);
 499   g_simple_async_result_set_op_res_gpointer (res, data, (GDestroyNotify)query_info_data_free);
 500
 501   g_simple_async_result_run_in_thread (res, query_info_async_thread, io_priority, cancellable);
 502   g_object_unref (res);
 503 }
 504
 505 static GFileInfo *
 506 g_file_input_stream_real_query_info_finish (GFileInputStream     *stream,
 507                                                GAsyncResult         *res,
 508                                                GError              **error)
 509 {
 510   GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
 511   QueryInfoAsyncData *data;
 512
 513   g_assert (g_simple_async_result_get_source_tag (simple) == g_file_input_stream_real_query_info_async);
 514
 515   data = g_simple_async_result_get_op_res_gpointer (simple);
 516   if (data->info)
 517     return g_object_ref (data->info);
 518
 519   return NULL;
 520 }