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 "gsimpleasyncresult.h"
  29 #include "glibintl.h"
  30
  31 #include "gioalias.h"
  32
  33 /**
  34  * SECTION:gfileoutputstream
  35  * @short_description: File output streaming operations
  36  * @include: 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. In addition to the generic g_seekable_ API,
  46  * GFileOutputStream has its own API for seeking and positioning.
  47  * To find the position of a file output stream, use
  48  * g_file_output_stream_tell(). To find out if a file output
  49  * stream supports seeking, use g_file_output_stream_can_seek().
  50  * To position a file output stream, use g_file_output_stream_seek().
  51  * To find out if a file output stream supports truncating, use
  52  * g_file_output_stream_can_truncate(). To truncate a file output
  53  * stream, use g_file_output_stream_truncate().
  54  **/
  55
  56 static void       g_file_output_stream_seekable_iface_init    (GSeekableIface       *iface);
  57 static goffset    g_file_output_stream_seekable_tell          (GSeekable            *seekable);
  58 static gboolean   g_file_output_stream_seekable_can_seek      (GSeekable            *seekable);
  59 static gboolean   g_file_output_stream_seekable_seek          (GSeekable            *seekable,
  60                                                                goffset               offset,
  61                                                                GSeekType             type,
  62                                                                GCancellable         *cancellable,
  63                                                                GError              **error);
  64 static gboolean   g_file_output_stream_seekable_can_truncate  (GSeekable            *seekable);
  65 static gboolean   g_file_output_stream_seekable_truncate      (GSeekable            *seekable,
  66                                                                goffset               offset,
  67                                                                GCancellable         *cancellable,
  68                                                                GError              **error);
  69 static void       g_file_output_stream_real_query_info_async  (GFileOutputStream    *stream,
  70                                                                char                 *attributes,
  71                                                                int                   io_priority,
  72                                                                GCancellable         *cancellable,
  73                                                                GAsyncReadyCallback   callback,
  74                                                                gpointer              user_data);
  75 static GFileInfo *g_file_output_stream_real_query_info_finish (GFileOutputStream    *stream,
  76                                                                GAsyncResult         *result,
  77                                                                GError              **error);
  78
  79 G_DEFINE_TYPE_WITH_CODE (GFileOutputStream, g_file_output_stream, G_TYPE_OUTPUT_STREAM,
  80                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  81                                                 g_file_output_stream_seekable_iface_init));
  82
  83 struct _GFileOutputStreamPrivate {
  84   GAsyncReadyCallback outstanding_callback;
  85 };
  86
  87 static void
  88 g_file_output_stream_class_init (GFileOutputStreamClass *klass)
  89 {
  90   g_type_class_add_private (klass, sizeof (GFileOutputStreamPrivate));
  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_TYPE_INSTANCE_GET_PRIVATE (stream,
 110                                               G_TYPE_FILE_OUTPUT_STREAM,
 111                                               GFileOutputStreamPrivate);
 112 }
 113
 114 /**
 115  * g_file_output_stream_query_info:
 116  * @stream: a #GFileOutputStream.
 117  * @attributes: a file attribute query string.
 118  * @cancellable: optional #GCancellable object, %NULL to ignore.
 119  * @error: a #GError, %NULL to ignore.
 120  *
 121  * Queries a file output stream for the given @attributes.
 122  * This function blocks while querying the stream. For the asynchronous
 123  * version of this function, see g_file_output_stream_query_info_async().
 124  * While the stream is blocked, the stream will set the pending flag
 125  * internally, and any other operations on the stream will fail with
 126  * %G_IO_ERROR_PENDING.
 127  *
 128  * Can fail if the stream was already closed (with @error being set to
 129  * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
 130  * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
 131  * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). In
 132  * all cases of failure, %NULL will be returned.
 133  *
 134  * If @cancellable is not %NULL, then the operation can be cancelled by
 135  * triggering the cancellable object from another thread. If the operation
 136  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
 137  * be returned.
 138  *
 139  * Returns: a #GFileInfo for the @stream, or %NULL on error.
 140  **/
 141 GFileInfo *
 142 g_file_output_stream_query_info (GFileOutputStream      *stream,
 143                                     char                   *attributes,
 144                                     GCancellable           *cancellable,
 145                                     GError                **error)
 146 {
 147   GFileOutputStreamClass *class;
 148   GOutputStream *output_stream;
 149   GFileInfo *info;
 150
 151   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 152
 153   output_stream = G_OUTPUT_STREAM (stream);
 154
 155   if (!g_output_stream_set_pending (output_stream, error))
 156     return NULL;
 157
 158   info = NULL;
 159
 160   if (cancellable)
 161     g_cancellable_push_current (cancellable);
 162
 163   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 164   if (class->query_info)
 165     info = class->query_info (stream, attributes, cancellable, error);
 166   else
 167     g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 168                  _("Stream doesn't support query_info"));
 169
 170   if (cancellable)
 171     g_cancellable_pop_current (cancellable);
 172
 173   g_output_stream_clear_pending (output_stream);
 174
 175   return info;
 176 }
 177
 178 static void
 179 async_ready_callback_wrapper (GObject *source_object,
 180                               GAsyncResult *res,
 181                               gpointer      user_data)
 182 {
 183   GFileOutputStream *stream = G_FILE_OUTPUT_STREAM (source_object);
 184
 185   g_output_stream_clear_pending (G_OUTPUT_STREAM (stream));
 186   if (stream->priv->outstanding_callback)
 187     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 188   g_object_unref (stream);
 189 }
 190
 191 /**
 192  * g_file_output_stream_query_info_async:
 193  * @stream: a #GFileOutputStream.
 194  * @attributes: a file attribute query string.
 195  * @io_priority: the <link linkend="gio-GIOScheduler">I/O priority</link>
 196  *     of the request.
 197  * @cancellable: optional #GCancellable object, %NULL to ignore.
 198  * @callback: callback to call when the request is satisfied
 199  * @user_data: the data to pass to callback function
 200  *
 201  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 202  * @callback will be called with a #GAsyncResult which can be used to
 203  * finish the operation with g_file_output_stream_query_info_finish().
 204  *
 205  * For the synchronous version of this function, see
 206  * g_file_output_stream_query_info().
 207  *
 208  **/
 209 void
 210 g_file_output_stream_query_info_async (GFileOutputStream     *stream,
 211                                           char                 *attributes,
 212                                           int                   io_priority,
 213                                           GCancellable         *cancellable,
 214                                           GAsyncReadyCallback   callback,
 215                                           gpointer              user_data)
 216 {
 217   GFileOutputStreamClass *klass;
 218   GOutputStream *output_stream;
 219   GError *error = NULL;
 220
 221   g_return_if_fail (G_IS_FILE_OUTPUT_STREAM (stream));
 222
 223   output_stream = G_OUTPUT_STREAM (stream);
 224
 225   if (!g_output_stream_set_pending (output_stream, &error))
 226     {
 227       g_simple_async_report_gerror_in_idle (G_OBJECT (stream),
 228                                             callback,
 229                                             user_data,
 230                                             error);
 231       g_error_free (error);
 232       return;
 233     }
 234
 235   klass = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 236
 237   stream->priv->outstanding_callback = callback;
 238   g_object_ref (stream);
 239   klass->query_info_async (stream, attributes, io_priority, cancellable,
 240                               async_ready_callback_wrapper, user_data);
 241 }
 242
 243 /**
 244  * g_file_output_stream_query_info_finish:
 245  * @stream: a #GFileOutputStream.
 246  * @result: a #GAsyncResult.
 247  * @error: a #GError, %NULL to ignore.
 248  *
 249  * Finalizes the asynchronous query started
 250  * by g_file_output_stream_query_info_async().
 251  *
 252  * Returns: A #GFileInfo for the finished query.
 253  **/
 254 GFileInfo *
 255 g_file_output_stream_query_info_finish (GFileOutputStream     *stream,
 256                                            GAsyncResult         *result,
 257                                            GError              **error)
 258 {
 259   GSimpleAsyncResult *simple;
 260   GFileOutputStreamClass *class;
 261
 262   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 263   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 264
 265   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 266     {
 267       simple = G_SIMPLE_ASYNC_RESULT (result);
 268       if (g_simple_async_result_propagate_error (simple, error))
 269         return NULL;
 270     }
 271
 272   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 273   return class->query_info_finish (stream, result, error);
 274 }
 275
 276 /**
 277  * g_file_output_stream_get_etag:
 278  * @stream: a #GFileOutputStream.
 279  *
 280  * Gets the entity tag for the file when its been written.
 281  * This must be called after the stream has been written
 282  * and closed. As the etag can change while writing.
 283  *
 284  * Returns: the entity tag for the stream.
 285  **/
 286 char *
 287 g_file_output_stream_get_etag (GFileOutputStream  *stream)
 288 {
 289   GFileOutputStreamClass *class;
 290   GOutputStream *output_stream;
 291   char *etag;
 292
 293   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 294
 295   output_stream = G_OUTPUT_STREAM (stream);
 296
 297   if (!g_output_stream_is_closed (output_stream))
 298     {
 299       g_warning ("stream is not closed yet, can't get etag");
 300       return NULL;
 301     }
 302
 303   etag = NULL;
 304
 305   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 306   if (class->get_etag)
 307     etag = class->get_etag (stream);
 308
 309   return etag;
 310 }
 311
 312 /**
 313  * g_file_output_stream_tell:
 314  * @stream: a #GFileOutputStream.
 315  *
 316  * Gets the current location within the stream.
 317  *
 318  * Returns: a #goffset of the location within the stream.
 319  **/
 320 goffset
 321 g_file_output_stream_tell (GFileOutputStream  *stream)
 322 {
 323   GFileOutputStreamClass *class;
 324   goffset offset;
 325
 326   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), 0);
 327
 328   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 329
 330   offset = 0;
 331   if (class->tell)
 332     offset = class->tell (stream);
 333
 334   return offset;
 335 }
 336
 337 static goffset
 338 g_file_output_stream_seekable_tell (GSeekable *seekable)
 339 {
 340   return g_file_output_stream_tell (G_FILE_OUTPUT_STREAM (seekable));
 341 }
 342
 343 /**
 344  * g_file_output_stream_can_seek:
 345  * @stream: a #GFileOutputStream.
 346  *
 347  * Checks if the stream can be seeked.
 348  *
 349  * Returns: %TRUE if seeking is supported by the stream.
 350  **/
 351 gboolean
 352 g_file_output_stream_can_seek (GFileOutputStream  *stream)
 353 {
 354   GFileOutputStreamClass *class;
 355   gboolean can_seek;
 356
 357   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 358
 359   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 360
 361   can_seek = FALSE;
 362   if (class->seek)
 363     {
 364       can_seek = TRUE;
 365       if (class->can_seek)
 366         can_seek = class->can_seek (stream);
 367     }
 368
 369   return can_seek;
 370 }
 371
 372 static gboolean
 373 g_file_output_stream_seekable_can_seek (GSeekable *seekable)
 374 {
 375   return g_file_output_stream_can_seek (G_FILE_OUTPUT_STREAM (seekable));
 376 }
 377
 378 /**
 379  * g_file_output_stream_seek:
 380  * @stream: a #GFileOutputStream.
 381  * @offset: a #goffset to seek.
 382  * @type: a #GSeekType.
 383  * @cancellable: optional #GCancellable object, %NULL to ignore.
 384  * @error: a #GError, %NULL to ignore.
 385  *
 386  * Seeks to a location in a file output stream.
 387  *
 388  * Returns: %TRUE if the seek was successful. %FALSE otherwise.
 389  **/
 390 gboolean
 391 g_file_output_stream_seek (GFileOutputStream  *stream,
 392                            goffset             offset,
 393                            GSeekType           type,
 394                            GCancellable       *cancellable,
 395                            GError            **error)
 396 {
 397   GFileOutputStreamClass *class;
 398   GOutputStream *output_stream;
 399   gboolean res;
 400
 401   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 402
 403   output_stream = G_OUTPUT_STREAM (stream);
 404   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 405
 406   if (!class->seek)
 407     {
 408       g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 409                    _("Seek not supported on stream"));
 410       return FALSE;
 411     }
 412
 413   if (!g_output_stream_set_pending (output_stream, error))
 414     return FALSE;
 415
 416   if (cancellable)
 417     g_cancellable_push_current (cancellable);
 418
 419   res = class->seek (stream, offset, type, cancellable, error);
 420
 421   if (cancellable)
 422     g_cancellable_pop_current (cancellable);
 423
 424   g_output_stream_clear_pending (output_stream);
 425
 426   return res;
 427 }
 428
 429 static gboolean
 430 g_file_output_stream_seekable_seek (GSeekable  *seekable,
 431                                     goffset     offset,
 432                                     GSeekType   type,
 433                                     GCancellable  *cancellable,
 434                                     GError    **error)
 435 {
 436   return g_file_output_stream_seek (G_FILE_OUTPUT_STREAM (seekable),
 437                                     offset, type, cancellable, error);
 438 }
 439
 440 /**
 441  * g_file_output_stream_can_truncate:
 442  * @stream: a #GFileOutputStream.
 443  *
 444  * Checks if the stream can be truncated.
 445  *
 446  * Returns: %TRUE if stream can be truncated.
 447  **/
 448 gboolean
 449 g_file_output_stream_can_truncate (GFileOutputStream  *stream)
 450 {
 451   GFileOutputStreamClass *class;
 452   gboolean can_truncate;
 453
 454   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 455
 456   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 457
 458   can_truncate = FALSE;
 459   if (class->truncate_fn)
 460     {
 461       can_truncate = TRUE;
 462       if (class->can_truncate)
 463         can_truncate = class->can_truncate (stream);
 464     }
 465
 466   return can_truncate;
 467 }
 468
 469 static gboolean
 470 g_file_output_stream_seekable_can_truncate (GSeekable  *seekable)
 471 {
 472   return g_file_output_stream_can_truncate (G_FILE_OUTPUT_STREAM (seekable));
 473 }
 474
 475 /**
 476  * g_file_output_stream_truncate:
 477  * @stream: a #GFileOutputStream.
 478  * @size: a #goffset to truncate the stream at.
 479  * @cancellable: optional #GCancellable object, %NULL to ignore.
 480  * @error: a #GError, %NULL to ignore.
 481  *
 482  * Truncates a file output stream.
 483  *
 484  * Returns: %TRUE if @stream is truncated successfully.
 485  **/
 486 gboolean
 487 g_file_output_stream_truncate (GFileOutputStream  *stream,
 488                                goffset             size,
 489                                GCancellable       *cancellable,
 490                                GError            **error)
 491 {
 492   GFileOutputStreamClass *class;
 493   GOutputStream *output_stream;
 494   gboolean res;
 495
 496   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 497
 498   output_stream = G_OUTPUT_STREAM (stream);
 499   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 500
 501   if (!class->truncate_fn)
 502     {
 503       g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 504                    _("Truncate not supported on stream"));
 505       return FALSE;
 506     }
 507
 508   if (!g_output_stream_set_pending (output_stream, error))
 509     return FALSE;
 510
 511   if (cancellable)
 512     g_cancellable_push_current (cancellable);
 513
 514   res = class->truncate_fn (stream, size, cancellable, error);
 515
 516   if (cancellable)
 517     g_cancellable_pop_current (cancellable);
 518
 519   g_output_stream_clear_pending (output_stream);
 520
 521   return res;
 522 }
 523
 524 static gboolean
 525 g_file_output_stream_seekable_truncate (GSeekable     *seekable,
 526                                         goffset        size,
 527                                         GCancellable  *cancellable,
 528                                         GError       **error)
 529 {
 530   return g_file_output_stream_truncate (G_FILE_OUTPUT_STREAM (seekable),
 531                                         size, cancellable, error);
 532 }
 533 /********************************************
 534  *   Default implementation of async ops    *
 535  ********************************************/
 536
 537 typedef struct {
 538   char *attributes;
 539   GFileInfo *info;
 540 } QueryInfoAsyncData;
 541
 542 static void
 543 query_info_data_free (QueryInfoAsyncData *data)
 544 {
 545   if (data->info)
 546     g_object_unref (data->info);
 547   g_free (data->attributes);
 548   g_free (data);
 549 }
 550
 551 static void
 552 query_info_async_thread (GSimpleAsyncResult *res,
 553                        GObject *object,
 554                        GCancellable *cancellable)
 555 {
 556   GFileOutputStreamClass *class;
 557   GError *error = NULL;
 558   QueryInfoAsyncData *data;
 559   GFileInfo *info;
 560
 561   data = g_simple_async_result_get_op_res_gpointer (res);
 562
 563   info = NULL;
 564
 565   class = G_FILE_OUTPUT_STREAM_GET_CLASS (object);
 566   if (class->query_info)
 567     info = class->query_info (G_FILE_OUTPUT_STREAM (object), data->attributes, cancellable, &error);
 568   else
 569     g_set_error (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 570                  _("Stream doesn't support query_info"));
 571
 572   if (info == NULL)
 573     {
 574       g_simple_async_result_set_from_error (res, error);
 575       g_error_free (error);
 576     }
 577   else
 578     data->info = info;
 579 }
 580
 581 static void
 582 g_file_output_stream_real_query_info_async (GFileOutputStream     *stream,
 583                                                char                 *attributes,
 584                                                int                   io_priority,
 585                                                GCancellable         *cancellable,
 586                                                GAsyncReadyCallback   callback,
 587                                                gpointer              user_data)
 588 {
 589   GSimpleAsyncResult *res;
 590   QueryInfoAsyncData *data;
 591
 592   data = g_new0 (QueryInfoAsyncData, 1);
 593   data->attributes = g_strdup (attributes);
 594
 595   res = g_simple_async_result_new (G_OBJECT (stream), callback, user_data, g_file_output_stream_real_query_info_async);
 596   g_simple_async_result_set_op_res_gpointer (res, data, (GDestroyNotify)query_info_data_free);
 597
 598   g_simple_async_result_run_in_thread (res, query_info_async_thread, io_priority, cancellable);
 599   g_object_unref (res);
 600 }
 601
 602 static GFileInfo *
 603 g_file_output_stream_real_query_info_finish (GFileOutputStream     *stream,
 604                                                 GAsyncResult         *res,
 605                                                 GError              **error)
 606 {
 607   GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
 608   QueryInfoAsyncData *data;
 609
 610   g_warn_if_fail (g_simple_async_result_get_source_tag (simple) == g_file_output_stream_real_query_info_async);
 611
 612   data = g_simple_async_result_get_op_res_gpointer (simple);
 613   if (data->info)
 614     return g_object_ref (data->info);
 615
 616   return NULL;
 617 }
 618
 619 #define __G_FILE_OUTPUT_STREAM_C__
 620 #include "gioaliasdef.c"