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, 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 <gfileoutputstream.h>
  27 #include <gseekable.h>
  28 #include "gasyncresult.h"
  29 #include "gtask.h"
  30 #include "gcancellable.h"
  31 #include "gioerror.h"
  32 #include "glibintl.h"
  33
  34
  35 /**
  36  * SECTION:gfileoutputstream
  37  * @short_description: File output streaming operations
  38  * @include: gio/gio.h
  39  * @see_also: #GOutputStream, #GDataOutputStream, #GSeekable
  40  *
  41  * GFileOutputStream provides output streams that write their
  42  * content to a file.
  43  *
  44  * GFileOutputStream implements #GSeekable, which allows the output
  45  * stream to jump to arbitrary positions in the file and to truncate
  46  * the file, provided the filesystem of the file supports these
  47  * operations.
  48  *
  49  * To find the position of a file output stream, use g_seekable_tell().
  50  * To find out if a file output stream supports seeking, use
  51  * g_seekable_can_seek().To position a file output stream, use
  52  * g_seekable_seek(). To find out if a file output stream supports
  53  * truncating, use g_seekable_can_truncate(). To truncate a file output
  54  * stream, use g_seekable_truncate().
  55  **/
  56
  57 static void       g_file_output_stream_seekable_iface_init    (GSeekableIface       *iface);
  58 static goffset    g_file_output_stream_seekable_tell          (GSeekable            *seekable);
  59 static gboolean   g_file_output_stream_seekable_can_seek      (GSeekable            *seekable);
  60 static gboolean   g_file_output_stream_seekable_seek          (GSeekable            *seekable,
  61                                                                goffset               offset,
  62                                                                GSeekType             type,
  63                                                                GCancellable         *cancellable,
  64                                                                GError              **error);
  65 static gboolean   g_file_output_stream_seekable_can_truncate  (GSeekable            *seekable);
  66 static gboolean   g_file_output_stream_seekable_truncate      (GSeekable            *seekable,
  67                                                                goffset               offset,
  68                                                                GCancellable         *cancellable,
  69                                                                GError              **error);
  70 static void       g_file_output_stream_real_query_info_async  (GFileOutputStream    *stream,
  71                                                                const char           *attributes,
  72                                                                int                   io_priority,
  73                                                                GCancellable         *cancellable,
  74                                                                GAsyncReadyCallback   callback,
  75                                                                gpointer              user_data);
  76 static GFileInfo *g_file_output_stream_real_query_info_finish (GFileOutputStream    *stream,
  77                                                                GAsyncResult         *result,
  78                                                                GError              **error);
  79
  80 struct _GFileOutputStreamPrivate {
  81   GAsyncReadyCallback outstanding_callback;
  82 };
  83
  84 G_DEFINE_TYPE_WITH_CODE (GFileOutputStream, g_file_output_stream, G_TYPE_OUTPUT_STREAM,
  85                          G_ADD_PRIVATE (GFileOutputStream)
  86                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  87                                                 g_file_output_stream_seekable_iface_init));
  88
  89 static void
  90 g_file_output_stream_class_init (GFileOutputStreamClass *klass)
  91 {
  92   klass->query_info_async = g_file_output_stream_real_query_info_async;
  93   klass->query_info_finish = g_file_output_stream_real_query_info_finish;
  94 }
  95
  96 static void
  97 g_file_output_stream_seekable_iface_init (GSeekableIface *iface)
  98 {
  99   iface->tell = g_file_output_stream_seekable_tell;
 100   iface->can_seek = g_file_output_stream_seekable_can_seek;
 101   iface->seek = g_file_output_stream_seekable_seek;
 102   iface->can_truncate = g_file_output_stream_seekable_can_truncate;
 103   iface->truncate_fn = g_file_output_stream_seekable_truncate;
 104 }
 105
 106 static void
 107 g_file_output_stream_init (GFileOutputStream *stream)
 108 {
 109   stream->priv = g_file_output_stream_get_private (stream);
 110 }
 111
 112 /**
 113  * g_file_output_stream_query_info:
 114  * @stream: a #GFileOutputStream.
 115  * @attributes: a file attribute query string.
 116  * @cancellable: optional #GCancellable object, %NULL to ignore.
 117  * @error: a #GError, %NULL to ignore.
 118  *
 119  * Queries a file output stream for the given @attributes.
 120  * This function blocks while querying the stream. For the asynchronous
 121  * version of this function, see g_file_output_stream_query_info_async().
 122  * While the stream is blocked, the stream will set the pending flag
 123  * internally, and any other operations on the stream will fail with
 124  * %G_IO_ERROR_PENDING.
 125  *
 126  * Can fail if the stream was already closed (with @error being set to
 127  * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
 128  * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
 129  * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). In
 130  * all cases of failure, %NULL will be returned.
 131  *
 132  * If @cancellable is not %NULL, then the operation can be cancelled by
 133  * triggering the cancellable object from another thread. If the operation
 134  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
 135  * be returned.
 136  *
 137  * Returns: (transfer full): a #GFileInfo for the @stream, or %NULL on error.
 138  **/
 139 GFileInfo *
 140 g_file_output_stream_query_info (GFileOutputStream      *stream,
 141                                     const char             *attributes,
 142                                     GCancellable           *cancellable,
 143                                     GError                **error)
 144 {
 145   GFileOutputStreamClass *class;
 146   GOutputStream *output_stream;
 147   GFileInfo *info;
 148
 149   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 150
 151   output_stream = G_OUTPUT_STREAM (stream);
 152
 153   if (!g_output_stream_set_pending (output_stream, error))
 154     return NULL;
 155
 156   info = NULL;
 157
 158   if (cancellable)
 159     g_cancellable_push_current (cancellable);
 160
 161   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 162   if (class->query_info)
 163     info = class->query_info (stream, attributes, cancellable, error);
 164   else
 165     g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 166                          _("Stream doesn't support query_info"));
 167
 168   if (cancellable)
 169     g_cancellable_pop_current (cancellable);
 170
 171   g_output_stream_clear_pending (output_stream);
 172
 173   return info;
 174 }
 175
 176 static void
 177 async_ready_callback_wrapper (GObject *source_object,
 178                               GAsyncResult *res,
 179                               gpointer      user_data)
 180 {
 181   GFileOutputStream *stream = G_FILE_OUTPUT_STREAM (source_object);
 182
 183   g_output_stream_clear_pending (G_OUTPUT_STREAM (stream));
 184   if (stream->priv->outstanding_callback)
 185     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 186   g_object_unref (stream);
 187 }
 188
 189 /**
 190  * g_file_output_stream_query_info_async:
 191  * @stream: a #GFileOutputStream.
 192  * @attributes: a file attribute query string.
 193  * @io_priority: the <link linkend="gio-GIOScheduler">I/O priority</link>
 194  *     of the request.
 195  * @cancellable: optional #GCancellable object, %NULL to ignore.
 196  * @callback: callback to call when the request is satisfied
 197  * @user_data: the data to pass to callback function
 198  *
 199  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 200  * @callback will be called with a #GAsyncResult which can be used to
 201  * finish the operation with g_file_output_stream_query_info_finish().
 202  *
 203  * For the synchronous version of this function, see
 204  * g_file_output_stream_query_info().
 205  *
 206  **/
 207 void
 208 g_file_output_stream_query_info_async (GFileOutputStream     *stream,
 209                                           const char           *attributes,
 210                                           int                   io_priority,
 211                                           GCancellable         *cancellable,
 212                                           GAsyncReadyCallback   callback,
 213                                           gpointer              user_data)
 214 {
 215   GFileOutputStreamClass *klass;
 216   GOutputStream *output_stream;
 217   GError *error = NULL;
 218
 219   g_return_if_fail (G_IS_FILE_OUTPUT_STREAM (stream));
 220
 221   output_stream = G_OUTPUT_STREAM (stream);
 222
 223   if (!g_output_stream_set_pending (output_stream, &error))
 224     {
 225       g_task_report_error (stream, callback, user_data,
 226                            g_file_output_stream_query_info_async,
 227                            error);
 228       return;
 229     }
 230
 231   klass = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 232
 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_output_stream_query_info_finish:
 241  * @stream: a #GFileOutputStream.
 242  * @result: a #GAsyncResult.
 243  * @error: a #GError, %NULL to ignore.
 244  *
 245  * Finalizes the asynchronous query started
 246  * by g_file_output_stream_query_info_async().
 247  *
 248  * Returns: (transfer full): A #GFileInfo for the finished query.
 249  **/
 250 GFileInfo *
 251 g_file_output_stream_query_info_finish (GFileOutputStream     *stream,
 252                                            GAsyncResult         *result,
 253                                            GError              **error)
 254 {
 255   GFileOutputStreamClass *class;
 256
 257   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 258   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 259
 260   if (g_async_result_legacy_propagate_error (result, error))
 261     return NULL;
 262   else if (g_async_result_is_tagged (result, g_file_output_stream_query_info_async))
 263     return g_task_propagate_pointer (G_TASK (result), error);
 264
 265   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 266   return class->query_info_finish (stream, result, error);
 267 }
 268
 269 /**
 270  * g_file_output_stream_get_etag:
 271  * @stream: a #GFileOutputStream.
 272  *
 273  * Gets the entity tag for the file when it has been written.
 274  * This must be called after the stream has been written
 275  * and closed, as the etag can change while writing.
 276  *
 277  * Returns: the entity tag for the stream.
 278  **/
 279 char *
 280 g_file_output_stream_get_etag (GFileOutputStream  *stream)
 281 {
 282   GFileOutputStreamClass *class;
 283   GOutputStream *output_stream;
 284   char *etag;
 285
 286   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 287
 288   output_stream = G_OUTPUT_STREAM (stream);
 289
 290   if (!g_output_stream_is_closed (output_stream))
 291     {
 292       g_warning ("stream is not closed yet, can't get etag");
 293       return NULL;
 294     }
 295
 296   etag = NULL;
 297
 298   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 299   if (class->get_etag)
 300     etag = class->get_etag (stream);
 301
 302   return etag;
 303 }
 304
 305 static goffset
 306 g_file_output_stream_tell (GFileOutputStream  *stream)
 307 {
 308   GFileOutputStreamClass *class;
 309   goffset offset;
 310
 311   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), 0);
 312
 313   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 314
 315   offset = 0;
 316   if (class->tell)
 317     offset = class->tell (stream);
 318
 319   return offset;
 320 }
 321
 322 static goffset
 323 g_file_output_stream_seekable_tell (GSeekable *seekable)
 324 {
 325   return g_file_output_stream_tell (G_FILE_OUTPUT_STREAM (seekable));
 326 }
 327
 328 static gboolean
 329 g_file_output_stream_can_seek (GFileOutputStream  *stream)
 330 {
 331   GFileOutputStreamClass *class;
 332   gboolean can_seek;
 333
 334   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 335
 336   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 337
 338   can_seek = FALSE;
 339   if (class->seek)
 340     {
 341       can_seek = TRUE;
 342       if (class->can_seek)
 343         can_seek = class->can_seek (stream);
 344     }
 345
 346   return can_seek;
 347 }
 348
 349 static gboolean
 350 g_file_output_stream_seekable_can_seek (GSeekable *seekable)
 351 {
 352   return g_file_output_stream_can_seek (G_FILE_OUTPUT_STREAM (seekable));
 353 }
 354
 355 static gboolean
 356 g_file_output_stream_seek (GFileOutputStream  *stream,
 357                            goffset             offset,
 358                            GSeekType           type,
 359                            GCancellable       *cancellable,
 360                            GError            **error)
 361 {
 362   GFileOutputStreamClass *class;
 363   GOutputStream *output_stream;
 364   gboolean res;
 365
 366   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 367
 368   output_stream = G_OUTPUT_STREAM (stream);
 369   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 370
 371   if (!class->seek)
 372     {
 373       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 374                            _("Seek not supported on stream"));
 375       return FALSE;
 376     }
 377
 378   if (!g_output_stream_set_pending (output_stream, error))
 379     return FALSE;
 380
 381   if (cancellable)
 382     g_cancellable_push_current (cancellable);
 383
 384   res = class->seek (stream, offset, type, cancellable, error);
 385
 386   if (cancellable)
 387     g_cancellable_pop_current (cancellable);
 388
 389   g_output_stream_clear_pending (output_stream);
 390
 391   return res;
 392 }
 393
 394 static gboolean
 395 g_file_output_stream_seekable_seek (GSeekable  *seekable,
 396                                     goffset     offset,
 397                                     GSeekType   type,
 398                                     GCancellable  *cancellable,
 399                                     GError    **error)
 400 {
 401   return g_file_output_stream_seek (G_FILE_OUTPUT_STREAM (seekable),
 402                                     offset, type, cancellable, error);
 403 }
 404
 405 static gboolean
 406 g_file_output_stream_can_truncate (GFileOutputStream  *stream)
 407 {
 408   GFileOutputStreamClass *class;
 409   gboolean can_truncate;
 410
 411   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 412
 413   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 414
 415   can_truncate = FALSE;
 416   if (class->truncate_fn)
 417     {
 418       can_truncate = TRUE;
 419       if (class->can_truncate)
 420         can_truncate = class->can_truncate (stream);
 421     }
 422
 423   return can_truncate;
 424 }
 425
 426 static gboolean
 427 g_file_output_stream_seekable_can_truncate (GSeekable  *seekable)
 428 {
 429   return g_file_output_stream_can_truncate (G_FILE_OUTPUT_STREAM (seekable));
 430 }
 431
 432 static gboolean
 433 g_file_output_stream_truncate (GFileOutputStream  *stream,
 434                                goffset             size,
 435                                GCancellable       *cancellable,
 436                                GError            **error)
 437 {
 438   GFileOutputStreamClass *class;
 439   GOutputStream *output_stream;
 440   gboolean res;
 441
 442   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 443
 444   output_stream = G_OUTPUT_STREAM (stream);
 445   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 446
 447   if (!class->truncate_fn)
 448     {
 449       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 450                            _("Truncate not supported on stream"));
 451       return FALSE;
 452     }
 453
 454   if (!g_output_stream_set_pending (output_stream, error))
 455     return FALSE;
 456
 457   if (cancellable)
 458     g_cancellable_push_current (cancellable);
 459
 460   res = class->truncate_fn (stream, size, cancellable, error);
 461
 462   if (cancellable)
 463     g_cancellable_pop_current (cancellable);
 464
 465   g_output_stream_clear_pending (output_stream);
 466
 467   return res;
 468 }
 469
 470 static gboolean
 471 g_file_output_stream_seekable_truncate (GSeekable     *seekable,
 472                                         goffset        size,
 473                                         GCancellable  *cancellable,
 474                                         GError       **error)
 475 {
 476   return g_file_output_stream_truncate (G_FILE_OUTPUT_STREAM (seekable),
 477                                         size, cancellable, error);
 478 }
 479 /********************************************
 480  *   Default implementation of async ops    *
 481  ********************************************/
 482
 483 static void
 484 query_info_async_thread (GTask        *task,
 485                          gpointer      source_object,
 486                          gpointer      task_data,
 487                          GCancellable *cancellable)
 488 {
 489   GFileOutputStream *stream = source_object;
 490   const char *attributes = task_data;
 491   GFileOutputStreamClass *class;
 492   GError *error = NULL;
 493   GFileInfo *info = NULL;
 494
 495   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 496   if (class->query_info)
 497     info = class->query_info (stream, attributes, cancellable, &error);
 498   else
 499     g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 500                          _("Stream doesn't support query_info"));
 501
 502   if (info == NULL)
 503     g_task_return_error (task, error);
 504   else
 505     g_task_return_pointer (task, info, g_object_unref);
 506 }
 507
 508 static void
 509 g_file_output_stream_real_query_info_async (GFileOutputStream     *stream,
 510                                                const char           *attributes,
 511                                                int                   io_priority,
 512                                                GCancellable         *cancellable,
 513                                                GAsyncReadyCallback   callback,
 514                                                gpointer              user_data)
 515 {
 516   GTask *task;
 517
 518   task = g_task_new (stream, cancellable, callback, user_data);
 519   g_task_set_task_data (task, g_strdup (attributes), g_free);
 520   g_task_set_priority (task, io_priority);
 521
 522   g_task_run_in_thread (task, query_info_async_thread);
 523   g_object_unref (task);
 524 }
 525
 526 static GFileInfo *
 527 g_file_output_stream_real_query_info_finish (GFileOutputStream     *stream,
 528                                              GAsyncResult         *res,
 529                                              GError              **error)
 530 {
 531   g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
 532
 533   return g_task_propagate_pointer (G_TASK (res), error);
 534 }