gio/gfileoutputstream.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, see <http://www.gnu.org/licenses/>.
  17  *
  18  * Author: Alexander Larsson <alexl@redhat.com>
  19  */
  20
  21 #include "config.h"
  22
  23 #include <glib.h>
  24 #include <gfileoutputstream.h>
  25 #include <gseekable.h>
  26 #include "gasyncresult.h"
  27 #include "gtask.h"
  28 #include "gcancellable.h"
  29 #include "gioerror.h"
  30 #include "glibintl.h"
  31
  32
  33 /**
  34  * SECTION:gfileoutputstream
  35  * @short_description: File output streaming operations
  36  * @include: gio/gio.h
  37  * @see_also: #GOutputStream, #GDataOutputStream, #GSeekable
  38  *
  39  * GFileOutputStream provides output streams that write their
  40  * content to a file.
  41  *
  42  * GFileOutputStream implements #GSeekable, which allows the output
  43  * stream to jump to arbitrary positions in the file and to truncate
  44  * the file, provided the filesystem of the file supports these
  45  * operations.
  46  *
  47  * To find the position of a file output stream, use g_seekable_tell().
  48  * To find out if a file output stream supports seeking, use
  49  * g_seekable_can_seek().To position a file output stream, use
  50  * g_seekable_seek(). To find out if a file output stream supports
  51  * truncating, use g_seekable_can_truncate(). To truncate a file output
  52  * stream, use g_seekable_truncate().
  53  **/
  54
  55 static void       g_file_output_stream_seekable_iface_init    (GSeekableIface       *iface);
  56 static goffset    g_file_output_stream_seekable_tell          (GSeekable            *seekable);
  57 static gboolean   g_file_output_stream_seekable_can_seek      (GSeekable            *seekable);
  58 static gboolean   g_file_output_stream_seekable_seek          (GSeekable            *seekable,
  59                                                                goffset               offset,
  60                                                                GSeekType             type,
  61                                                                GCancellable         *cancellable,
  62                                                                GError              **error);
  63 static gboolean   g_file_output_stream_seekable_can_truncate  (GSeekable            *seekable);
  64 static gboolean   g_file_output_stream_seekable_truncate      (GSeekable            *seekable,
  65                                                                goffset               offset,
  66                                                                GCancellable         *cancellable,
  67                                                                GError              **error);
  68 static void       g_file_output_stream_real_query_info_async  (GFileOutputStream    *stream,
  69                                                                const char           *attributes,
  70                                                                int                   io_priority,
  71                                                                GCancellable         *cancellable,
  72                                                                GAsyncReadyCallback   callback,
  73                                                                gpointer              user_data);
  74 static GFileInfo *g_file_output_stream_real_query_info_finish (GFileOutputStream    *stream,
  75                                                                GAsyncResult         *result,
  76                                                                GError              **error);
  77
  78 struct _GFileOutputStreamPrivate {
  79   GAsyncReadyCallback outstanding_callback;
  80 };
  81
  82 G_DEFINE_TYPE_WITH_CODE (GFileOutputStream, g_file_output_stream, G_TYPE_OUTPUT_STREAM,
  83                          G_ADD_PRIVATE (GFileOutputStream)
  84                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  85                                                 g_file_output_stream_seekable_iface_init));
  86
  87 static void
  88 g_file_output_stream_class_init (GFileOutputStreamClass *klass)
  89 {
  90   klass->query_info_async = g_file_output_stream_real_query_info_async;
  91   klass->query_info_finish = g_file_output_stream_real_query_info_finish;
  92 }
  93
  94 static void
  95 g_file_output_stream_seekable_iface_init (GSeekableIface *iface)
  96 {
  97   iface->tell = g_file_output_stream_seekable_tell;
  98   iface->can_seek = g_file_output_stream_seekable_can_seek;
  99   iface->seek = g_file_output_stream_seekable_seek;
 100   iface->can_truncate = g_file_output_stream_seekable_can_truncate;
 101   iface->truncate_fn = g_file_output_stream_seekable_truncate;
 102 }
 103
 104 static void
 105 g_file_output_stream_init (GFileOutputStream *stream)
 106 {
 107   stream->priv = g_file_output_stream_get_instance_private (stream);
 108 }
 109
 110 /**
 111  * g_file_output_stream_query_info:
 112  * @stream: a #GFileOutputStream.
 113  * @attributes: a file attribute query string.
 114  * @cancellable: optional #GCancellable object, %NULL to ignore.
 115  * @error: a #GError, %NULL to ignore.
 116  *
 117  * Queries a file output stream for the given @attributes.
 118  * This function blocks while querying the stream. For the asynchronous
 119  * version of this function, see g_file_output_stream_query_info_async().
 120  * While the stream is blocked, the stream will set the pending flag
 121  * internally, and any other operations on the stream will fail with
 122  * %G_IO_ERROR_PENDING.
 123  *
 124  * Can fail if the stream was already closed (with @error being set to
 125  * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
 126  * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
 127  * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). In
 128  * all cases of failure, %NULL will be returned.
 129  *
 130  * If @cancellable is not %NULL, then the operation can be cancelled by
 131  * triggering the cancellable object from another thread. If the operation
 132  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
 133  * be returned.
 134  *
 135  * Returns: (transfer full): a #GFileInfo for the @stream, or %NULL on error.
 136  **/
 137 GFileInfo *
 138 g_file_output_stream_query_info (GFileOutputStream      *stream,
 139                                     const char             *attributes,
 140                                     GCancellable           *cancellable,
 141                                     GError                **error)
 142 {
 143   GFileOutputStreamClass *class;
 144   GOutputStream *output_stream;
 145   GFileInfo *info;
 146
 147   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 148
 149   output_stream = G_OUTPUT_STREAM (stream);
 150
 151   if (!g_output_stream_set_pending (output_stream, error))
 152     return NULL;
 153
 154   info = NULL;
 155
 156   if (cancellable)
 157     g_cancellable_push_current (cancellable);
 158
 159   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 160   if (class->query_info)
 161     info = class->query_info (stream, attributes, cancellable, error);
 162   else
 163     g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 164                          _("Stream doesn't support query_info"));
 165
 166   if (cancellable)
 167     g_cancellable_pop_current (cancellable);
 168
 169   g_output_stream_clear_pending (output_stream);
 170
 171   return info;
 172 }
 173
 174 static void
 175 async_ready_callback_wrapper (GObject *source_object,
 176                               GAsyncResult *res,
 177                               gpointer      user_data)
 178 {
 179   GFileOutputStream *stream = G_FILE_OUTPUT_STREAM (source_object);
 180
 181   g_output_stream_clear_pending (G_OUTPUT_STREAM (stream));
 182   if (stream->priv->outstanding_callback)
 183     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 184   g_object_unref (stream);
 185 }
 186
 187 /**
 188  * g_file_output_stream_query_info_async:
 189  * @stream: a #GFileOutputStream.
 190  * @attributes: a file attribute query string.
 191  * @io_priority: the <link linkend="gio-GIOScheduler">I/O priority</link>
 192  *     of the request.
 193  * @cancellable: optional #GCancellable object, %NULL to ignore.
 194  * @callback: callback to call when the request is satisfied
 195  * @user_data: the data to pass to callback function
 196  *
 197  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 198  * @callback will be called with a #GAsyncResult which can be used to
 199  * finish the operation with g_file_output_stream_query_info_finish().
 200  *
 201  * For the synchronous version of this function, see
 202  * g_file_output_stream_query_info().
 203  *
 204  **/
 205 void
 206 g_file_output_stream_query_info_async (GFileOutputStream     *stream,
 207                                           const char           *attributes,
 208                                           int                   io_priority,
 209                                           GCancellable         *cancellable,
 210                                           GAsyncReadyCallback   callback,
 211                                           gpointer              user_data)
 212 {
 213   GFileOutputStreamClass *klass;
 214   GOutputStream *output_stream;
 215   GError *error = NULL;
 216
 217   g_return_if_fail (G_IS_FILE_OUTPUT_STREAM (stream));
 218
 219   output_stream = G_OUTPUT_STREAM (stream);
 220
 221   if (!g_output_stream_set_pending (output_stream, &error))
 222     {
 223       g_task_report_error (stream, callback, user_data,
 224                            g_file_output_stream_query_info_async,
 225                            error);
 226       return;
 227     }
 228
 229   klass = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 230
 231   stream->priv->outstanding_callback = callback;
 232   g_object_ref (stream);
 233   klass->query_info_async (stream, attributes, io_priority, cancellable,
 234                            async_ready_callback_wrapper, user_data);
 235 }
 236
 237 /**
 238  * g_file_output_stream_query_info_finish:
 239  * @stream: a #GFileOutputStream.
 240  * @result: a #GAsyncResult.
 241  * @error: a #GError, %NULL to ignore.
 242  *
 243  * Finalizes the asynchronous query started
 244  * by g_file_output_stream_query_info_async().
 245  *
 246  * Returns: (transfer full): A #GFileInfo for the finished query.
 247  **/
 248 GFileInfo *
 249 g_file_output_stream_query_info_finish (GFileOutputStream     *stream,
 250                                            GAsyncResult         *result,
 251                                            GError              **error)
 252 {
 253   GFileOutputStreamClass *class;
 254
 255   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 256   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 257
 258   if (g_async_result_legacy_propagate_error (result, error))
 259     return NULL;
 260   else if (g_async_result_is_tagged (result, g_file_output_stream_query_info_async))
 261     return g_task_propagate_pointer (G_TASK (result), error);
 262
 263   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 264   return class->query_info_finish (stream, result, error);
 265 }
 266
 267 /**
 268  * g_file_output_stream_get_etag:
 269  * @stream: a #GFileOutputStream.
 270  *
 271  * Gets the entity tag for the file when it has been written.
 272  * This must be called after the stream has been written
 273  * and closed, as the etag can change while writing.
 274  *
 275  * Returns: the entity tag for the stream.
 276  **/
 277 char *
 278 g_file_output_stream_get_etag (GFileOutputStream  *stream)
 279 {
 280   GFileOutputStreamClass *class;
 281   GOutputStream *output_stream;
 282   char *etag;
 283
 284   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 285
 286   output_stream = G_OUTPUT_STREAM (stream);
 287
 288   if (!g_output_stream_is_closed (output_stream))
 289     {
 290       g_warning ("stream is not closed yet, can't get etag");
 291       return NULL;
 292     }
 293
 294   etag = NULL;
 295
 296   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 297   if (class->get_etag)
 298     etag = class->get_etag (stream);
 299
 300   return etag;
 301 }
 302
 303 static goffset
 304 g_file_output_stream_tell (GFileOutputStream  *stream)
 305 {
 306   GFileOutputStreamClass *class;
 307   goffset offset;
 308
 309   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), 0);
 310
 311   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 312
 313   offset = 0;
 314   if (class->tell)
 315     offset = class->tell (stream);
 316
 317   return offset;
 318 }
 319
 320 static goffset
 321 g_file_output_stream_seekable_tell (GSeekable *seekable)
 322 {
 323   return g_file_output_stream_tell (G_FILE_OUTPUT_STREAM (seekable));
 324 }
 325
 326 static gboolean
 327 g_file_output_stream_can_seek (GFileOutputStream  *stream)
 328 {
 329   GFileOutputStreamClass *class;
 330   gboolean can_seek;
 331
 332   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 333
 334   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 335
 336   can_seek = FALSE;
 337   if (class->seek)
 338     {
 339       can_seek = TRUE;
 340       if (class->can_seek)
 341         can_seek = class->can_seek (stream);
 342     }
 343
 344   return can_seek;
 345 }
 346
 347 static gboolean
 348 g_file_output_stream_seekable_can_seek (GSeekable *seekable)
 349 {
 350   return g_file_output_stream_can_seek (G_FILE_OUTPUT_STREAM (seekable));
 351 }
 352
 353 static gboolean
 354 g_file_output_stream_seek (GFileOutputStream  *stream,
 355                            goffset             offset,
 356                            GSeekType           type,
 357                            GCancellable       *cancellable,
 358                            GError            **error)
 359 {
 360   GFileOutputStreamClass *class;
 361   GOutputStream *output_stream;
 362   gboolean res;
 363
 364   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 365
 366   output_stream = G_OUTPUT_STREAM (stream);
 367   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 368
 369   if (!class->seek)
 370     {
 371       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 372                            _("Seek not supported on stream"));
 373       return FALSE;
 374     }
 375
 376   if (!g_output_stream_set_pending (output_stream, error))
 377     return FALSE;
 378
 379   if (cancellable)
 380     g_cancellable_push_current (cancellable);
 381
 382   res = class->seek (stream, offset, type, cancellable, error);
 383
 384   if (cancellable)
 385     g_cancellable_pop_current (cancellable);
 386
 387   g_output_stream_clear_pending (output_stream);
 388
 389   return res;
 390 }
 391
 392 static gboolean
 393 g_file_output_stream_seekable_seek (GSeekable  *seekable,
 394                                     goffset     offset,
 395                                     GSeekType   type,
 396                                     GCancellable  *cancellable,
 397                                     GError    **error)
 398 {
 399   return g_file_output_stream_seek (G_FILE_OUTPUT_STREAM (seekable),
 400                                     offset, type, cancellable, error);
 401 }
 402
 403 static gboolean
 404 g_file_output_stream_can_truncate (GFileOutputStream  *stream)
 405 {
 406   GFileOutputStreamClass *class;
 407   gboolean can_truncate;
 408
 409   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 410
 411   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 412
 413   can_truncate = FALSE;
 414   if (class->truncate_fn)
 415     {
 416       can_truncate = TRUE;
 417       if (class->can_truncate)
 418         can_truncate = class->can_truncate (stream);
 419     }
 420
 421   return can_truncate;
 422 }
 423
 424 static gboolean
 425 g_file_output_stream_seekable_can_truncate (GSeekable  *seekable)
 426 {
 427   return g_file_output_stream_can_truncate (G_FILE_OUTPUT_STREAM (seekable));
 428 }
 429
 430 static gboolean
 431 g_file_output_stream_truncate (GFileOutputStream  *stream,
 432                                goffset             size,
 433                                GCancellable       *cancellable,
 434                                GError            **error)
 435 {
 436   GFileOutputStreamClass *class;
 437   GOutputStream *output_stream;
 438   gboolean res;
 439
 440   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 441
 442   output_stream = G_OUTPUT_STREAM (stream);
 443   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 444
 445   if (!class->truncate_fn)
 446     {
 447       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 448                            _("Truncate not supported on stream"));
 449       return FALSE;
 450     }
 451
 452   if (!g_output_stream_set_pending (output_stream, error))
 453     return FALSE;
 454
 455   if (cancellable)
 456     g_cancellable_push_current (cancellable);
 457
 458   res = class->truncate_fn (stream, size, cancellable, error);
 459
 460   if (cancellable)
 461     g_cancellable_pop_current (cancellable);
 462
 463   g_output_stream_clear_pending (output_stream);
 464
 465   return res;
 466 }
 467
 468 static gboolean
 469 g_file_output_stream_seekable_truncate (GSeekable     *seekable,
 470                                         goffset        size,
 471                                         GCancellable  *cancellable,
 472                                         GError       **error)
 473 {
 474   return g_file_output_stream_truncate (G_FILE_OUTPUT_STREAM (seekable),
 475                                         size, cancellable, error);
 476 }
 477 /********************************************
 478  *   Default implementation of async ops    *
 479  ********************************************/
 480
 481 static void
 482 query_info_async_thread (GTask        *task,
 483                          gpointer      source_object,
 484                          gpointer      task_data,
 485                          GCancellable *cancellable)
 486 {
 487   GFileOutputStream *stream = source_object;
 488   const char *attributes = task_data;
 489   GFileOutputStreamClass *class;
 490   GError *error = NULL;
 491   GFileInfo *info = NULL;
 492
 493   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 494   if (class->query_info)
 495     info = class->query_info (stream, attributes, cancellable, &error);
 496   else
 497     g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 498                          _("Stream doesn't support query_info"));
 499
 500   if (info == NULL)
 501     g_task_return_error (task, error);
 502   else
 503     g_task_return_pointer (task, info, g_object_unref);
 504 }
 505
 506 static void
 507 g_file_output_stream_real_query_info_async (GFileOutputStream     *stream,
 508                                                const char           *attributes,
 509                                                int                   io_priority,
 510                                                GCancellable         *cancellable,
 511                                                GAsyncReadyCallback   callback,
 512                                                gpointer              user_data)
 513 {
 514   GTask *task;
 515
 516   task = g_task_new (stream, cancellable, callback, user_data);
 517   g_task_set_task_data (task, g_strdup (attributes), g_free);
 518   g_task_set_priority (task, io_priority);
 519
 520   g_task_run_in_thread (task, query_info_async_thread);
 521   g_object_unref (task);
 522 }
 523
 524 static GFileInfo *
 525 g_file_output_stream_real_query_info_finish (GFileOutputStream     *stream,
 526                                              GAsyncResult         *res,
 527                                              GError              **error)
 528 {
 529   g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
 530
 531   return g_task_propagate_pointer (G_TASK (res), error);
 532 }