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 [I/O priority][gio-GIOScheduler] of the request
 192  * @cancellable: optional #GCancellable object, %NULL to ignore.
 193  * @callback: callback to call when the request is satisfied
 194  * @user_data: the data to pass to callback function
 195  *
 196  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 197  * @callback will be called with a #GAsyncResult which can be used to
 198  * finish the operation with g_file_output_stream_query_info_finish().
 199  *
 200  * For the synchronous version of this function, see
 201  * g_file_output_stream_query_info().
 202  *
 203  **/
 204 void
 205 g_file_output_stream_query_info_async (GFileOutputStream     *stream,
 206                                           const char           *attributes,
 207                                           int                   io_priority,
 208                                           GCancellable         *cancellable,
 209                                           GAsyncReadyCallback   callback,
 210                                           gpointer              user_data)
 211 {
 212   GFileOutputStreamClass *klass;
 213   GOutputStream *output_stream;
 214   GError *error = NULL;
 215
 216   g_return_if_fail (G_IS_FILE_OUTPUT_STREAM (stream));
 217
 218   output_stream = G_OUTPUT_STREAM (stream);
 219
 220   if (!g_output_stream_set_pending (output_stream, &error))
 221     {
 222       g_task_report_error (stream, callback, user_data,
 223                            g_file_output_stream_query_info_async,
 224                            error);
 225       return;
 226     }
 227
 228   klass = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 229
 230   stream->priv->outstanding_callback = callback;
 231   g_object_ref (stream);
 232   klass->query_info_async (stream, attributes, io_priority, cancellable,
 233                            async_ready_callback_wrapper, user_data);
 234 }
 235
 236 /**
 237  * g_file_output_stream_query_info_finish:
 238  * @stream: a #GFileOutputStream.
 239  * @result: a #GAsyncResult.
 240  * @error: a #GError, %NULL to ignore.
 241  *
 242  * Finalizes the asynchronous query started
 243  * by g_file_output_stream_query_info_async().
 244  *
 245  * Returns: (transfer full): A #GFileInfo for the finished query.
 246  **/
 247 GFileInfo *
 248 g_file_output_stream_query_info_finish (GFileOutputStream     *stream,
 249                                            GAsyncResult         *result,
 250                                            GError              **error)
 251 {
 252   GFileOutputStreamClass *class;
 253
 254   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 255   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 256
 257   if (g_async_result_legacy_propagate_error (result, error))
 258     return NULL;
 259   else if (g_async_result_is_tagged (result, g_file_output_stream_query_info_async))
 260     return g_task_propagate_pointer (G_TASK (result), error);
 261
 262   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 263   return class->query_info_finish (stream, result, error);
 264 }
 265
 266 /**
 267  * g_file_output_stream_get_etag:
 268  * @stream: a #GFileOutputStream.
 269  *
 270  * Gets the entity tag for the file when it has been written.
 271  * This must be called after the stream has been written
 272  * and closed, as the etag can change while writing.
 273  *
 274  * Returns: the entity tag for the stream.
 275  **/
 276 char *
 277 g_file_output_stream_get_etag (GFileOutputStream  *stream)
 278 {
 279   GFileOutputStreamClass *class;
 280   GOutputStream *output_stream;
 281   char *etag;
 282
 283   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 284
 285   output_stream = G_OUTPUT_STREAM (stream);
 286
 287   if (!g_output_stream_is_closed (output_stream))
 288     {
 289       g_warning ("stream is not closed yet, can't get etag");
 290       return NULL;
 291     }
 292
 293   etag = NULL;
 294
 295   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 296   if (class->get_etag)
 297     etag = class->get_etag (stream);
 298
 299   return etag;
 300 }
 301
 302 static goffset
 303 g_file_output_stream_tell (GFileOutputStream  *stream)
 304 {
 305   GFileOutputStreamClass *class;
 306   goffset offset;
 307
 308   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), 0);
 309
 310   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 311
 312   offset = 0;
 313   if (class->tell)
 314     offset = class->tell (stream);
 315
 316   return offset;
 317 }
 318
 319 static goffset
 320 g_file_output_stream_seekable_tell (GSeekable *seekable)
 321 {
 322   return g_file_output_stream_tell (G_FILE_OUTPUT_STREAM (seekable));
 323 }
 324
 325 static gboolean
 326 g_file_output_stream_can_seek (GFileOutputStream  *stream)
 327 {
 328   GFileOutputStreamClass *class;
 329   gboolean can_seek;
 330
 331   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 332
 333   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 334
 335   can_seek = FALSE;
 336   if (class->seek)
 337     {
 338       can_seek = TRUE;
 339       if (class->can_seek)
 340         can_seek = class->can_seek (stream);
 341     }
 342
 343   return can_seek;
 344 }
 345
 346 static gboolean
 347 g_file_output_stream_seekable_can_seek (GSeekable *seekable)
 348 {
 349   return g_file_output_stream_can_seek (G_FILE_OUTPUT_STREAM (seekable));
 350 }
 351
 352 static gboolean
 353 g_file_output_stream_seek (GFileOutputStream  *stream,
 354                            goffset             offset,
 355                            GSeekType           type,
 356                            GCancellable       *cancellable,
 357                            GError            **error)
 358 {
 359   GFileOutputStreamClass *class;
 360   GOutputStream *output_stream;
 361   gboolean res;
 362
 363   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 364
 365   output_stream = G_OUTPUT_STREAM (stream);
 366   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 367
 368   if (!class->seek)
 369     {
 370       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 371                            _("Seek not supported on stream"));
 372       return FALSE;
 373     }
 374
 375   if (!g_output_stream_set_pending (output_stream, error))
 376     return FALSE;
 377
 378   if (cancellable)
 379     g_cancellable_push_current (cancellable);
 380
 381   res = class->seek (stream, offset, type, cancellable, error);
 382
 383   if (cancellable)
 384     g_cancellable_pop_current (cancellable);
 385
 386   g_output_stream_clear_pending (output_stream);
 387
 388   return res;
 389 }
 390
 391 static gboolean
 392 g_file_output_stream_seekable_seek (GSeekable  *seekable,
 393                                     goffset     offset,
 394                                     GSeekType   type,
 395                                     GCancellable  *cancellable,
 396                                     GError    **error)
 397 {
 398   return g_file_output_stream_seek (G_FILE_OUTPUT_STREAM (seekable),
 399                                     offset, type, cancellable, error);
 400 }
 401
 402 static gboolean
 403 g_file_output_stream_can_truncate (GFileOutputStream  *stream)
 404 {
 405   GFileOutputStreamClass *class;
 406   gboolean can_truncate;
 407
 408   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 409
 410   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 411
 412   can_truncate = FALSE;
 413   if (class->truncate_fn)
 414     {
 415       can_truncate = TRUE;
 416       if (class->can_truncate)
 417         can_truncate = class->can_truncate (stream);
 418     }
 419
 420   return can_truncate;
 421 }
 422
 423 static gboolean
 424 g_file_output_stream_seekable_can_truncate (GSeekable  *seekable)
 425 {
 426   return g_file_output_stream_can_truncate (G_FILE_OUTPUT_STREAM (seekable));
 427 }
 428
 429 static gboolean
 430 g_file_output_stream_truncate (GFileOutputStream  *stream,
 431                                goffset             size,
 432                                GCancellable       *cancellable,
 433                                GError            **error)
 434 {
 435   GFileOutputStreamClass *class;
 436   GOutputStream *output_stream;
 437   gboolean res;
 438
 439   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 440
 441   output_stream = G_OUTPUT_STREAM (stream);
 442   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 443
 444   if (!class->truncate_fn)
 445     {
 446       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 447                            _("Truncate not supported on stream"));
 448       return FALSE;
 449     }
 450
 451   if (!g_output_stream_set_pending (output_stream, error))
 452     return FALSE;
 453
 454   if (cancellable)
 455     g_cancellable_push_current (cancellable);
 456
 457   res = class->truncate_fn (stream, size, cancellable, error);
 458
 459   if (cancellable)
 460     g_cancellable_pop_current (cancellable);
 461
 462   g_output_stream_clear_pending (output_stream);
 463
 464   return res;
 465 }
 466
 467 static gboolean
 468 g_file_output_stream_seekable_truncate (GSeekable     *seekable,
 469                                         goffset        size,
 470                                         GCancellable  *cancellable,
 471                                         GError       **error)
 472 {
 473   return g_file_output_stream_truncate (G_FILE_OUTPUT_STREAM (seekable),
 474                                         size, cancellable, error);
 475 }
 476 /********************************************
 477  *   Default implementation of async ops    *
 478  ********************************************/
 479
 480 static void
 481 query_info_async_thread (GTask        *task,
 482                          gpointer      source_object,
 483                          gpointer      task_data,
 484                          GCancellable *cancellable)
 485 {
 486   GFileOutputStream *stream = source_object;
 487   const char *attributes = task_data;
 488   GFileOutputStreamClass *class;
 489   GError *error = NULL;
 490   GFileInfo *info = NULL;
 491
 492   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 493   if (class->query_info)
 494     info = class->query_info (stream, attributes, cancellable, &error);
 495   else
 496     g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 497                          _("Stream doesn't support query_info"));
 498
 499   if (info == NULL)
 500     g_task_return_error (task, error);
 501   else
 502     g_task_return_pointer (task, info, g_object_unref);
 503 }
 504
 505 static void
 506 g_file_output_stream_real_query_info_async (GFileOutputStream     *stream,
 507                                                const char           *attributes,
 508                                                int                   io_priority,
 509                                                GCancellable         *cancellable,
 510                                                GAsyncReadyCallback   callback,
 511                                                gpointer              user_data)
 512 {
 513   GTask *task;
 514
 515   task = g_task_new (stream, cancellable, callback, user_data);
 516   g_task_set_task_data (task, g_strdup (attributes), g_free);
 517   g_task_set_priority (task, io_priority);
 518
 519   g_task_run_in_thread (task, query_info_async_thread);
 520   g_object_unref (task);
 521 }
 522
 523 static GFileInfo *
 524 g_file_output_stream_real_query_info_finish (GFileOutputStream     *stream,
 525                                              GAsyncResult         *res,
 526                                              GError              **error)
 527 {
 528   g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
 529
 530   return g_task_propagate_pointer (G_TASK (res), error);
 531 }