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
  43  * the output stream to jump to arbitrary positions in the file.
  44  **/
  45
  46 static void       g_file_output_stream_seekable_iface_init    (GSeekableIface       *iface);
  47 static goffset    g_file_output_stream_seekable_tell          (GSeekable            *seekable);
  48 static gboolean   g_file_output_stream_seekable_can_seek      (GSeekable            *seekable);
  49 static gboolean   g_file_output_stream_seekable_seek          (GSeekable            *seekable,
  50                                                                goffset               offset,
  51                                                                GSeekType             type,
  52                                                                GCancellable         *cancellable,
  53                                                                GError              **error);
  54 static gboolean   g_file_output_stream_seekable_can_truncate  (GSeekable            *seekable);
  55 static gboolean   g_file_output_stream_seekable_truncate      (GSeekable            *seekable,
  56                                                                goffset               offset,
  57                                                                GCancellable         *cancellable,
  58                                                                GError              **error);
  59 static void       g_file_output_stream_real_query_info_async  (GFileOutputStream    *stream,
  60                                                                char                 *attributes,
  61                                                                int                   io_priority,
  62                                                                GCancellable         *cancellable,
  63                                                                GAsyncReadyCallback   callback,
  64                                                                gpointer              user_data);
  65 static GFileInfo *g_file_output_stream_real_query_info_finish (GFileOutputStream    *stream,
  66                                                                GAsyncResult         *result,
  67                                                                GError              **error);
  68
  69 G_DEFINE_TYPE_WITH_CODE (GFileOutputStream, g_file_output_stream, G_TYPE_OUTPUT_STREAM,
  70                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  71                                                 g_file_output_stream_seekable_iface_init));
  72
  73 struct _GFileOutputStreamPrivate {
  74   GAsyncReadyCallback outstanding_callback;
  75 };
  76
  77 static void
  78 g_file_output_stream_class_init (GFileOutputStreamClass *klass)
  79 {
  80   g_type_class_add_private (klass, sizeof (GFileOutputStreamPrivate));
  81
  82   klass->query_info_async = g_file_output_stream_real_query_info_async;
  83   klass->query_info_finish = g_file_output_stream_real_query_info_finish;
  84 }
  85
  86 static void
  87 g_file_output_stream_seekable_iface_init (GSeekableIface *iface)
  88 {
  89   iface->tell = g_file_output_stream_seekable_tell;
  90   iface->can_seek = g_file_output_stream_seekable_can_seek;
  91   iface->seek = g_file_output_stream_seekable_seek;
  92   iface->can_truncate = g_file_output_stream_seekable_can_truncate;
  93   iface->truncate_fn = g_file_output_stream_seekable_truncate;
  94 }
  95
  96 static void
  97 g_file_output_stream_init (GFileOutputStream *stream)
  98 {
  99   stream->priv = G_TYPE_INSTANCE_GET_PRIVATE (stream,
 100                                               G_TYPE_FILE_OUTPUT_STREAM,
 101                                               GFileOutputStreamPrivate);
 102 }
 103
 104 /**
 105  * g_file_output_stream_query_info:
 106  * @stream: a #GFileOutputStream.
 107  * @attributes: a file attribute query string.
 108  * @cancellable: optional #GCancellable object, %NULL to ignore.
 109  * @error: a #GError, %NULL to ignore.
 110  *
 111  * Queries a file output stream for the given @attributes.
 112  * This function blocks while querying the stream. For the asynchronous
 113  * version of this function, see g_file_output_stream_query_info_async().
 114  * While the stream is blocked, the stream will set the pending flag
 115  * internally, and any other operations on the stream will fail with
 116  * %G_IO_ERROR_PENDING.
 117  *
 118  * Can fail if the stream was already closed (with @error being set to
 119  * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
 120  * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
 121  * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). In
 122  * all cases of failure, %NULL will be returned.
 123  *
 124  * If @cancellable is not %NULL, then the operation can be cancelled by
 125  * triggering the cancellable object from another thread. If the operation
 126  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
 127  * be returned.
 128  *
 129  * Returns: a #GFileInfo for the @stream, or %NULL on error.
 130  **/
 131 GFileInfo *
 132 g_file_output_stream_query_info (GFileOutputStream      *stream,
 133                                     char                   *attributes,
 134                                     GCancellable           *cancellable,
 135                                     GError                **error)
 136 {
 137   GFileOutputStreamClass *class;
 138   GOutputStream *output_stream;
 139   GFileInfo *info;
 140
 141   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 142
 143   output_stream = G_OUTPUT_STREAM (stream);
 144
 145   if (!g_output_stream_set_pending (output_stream, error))
 146     return NULL;
 147
 148   info = NULL;
 149
 150   if (cancellable)
 151     g_cancellable_push_current (cancellable);
 152
 153   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 154   if (class->query_info)
 155     info = class->query_info (stream, attributes, cancellable, error);
 156   else
 157     g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 158                  _("Stream doesn't support query_info"));
 159
 160   if (cancellable)
 161     g_cancellable_pop_current (cancellable);
 162
 163   g_output_stream_clear_pending (output_stream);
 164
 165   return info;
 166 }
 167
 168 static void
 169 async_ready_callback_wrapper (GObject *source_object,
 170                               GAsyncResult *res,
 171                               gpointer      user_data)
 172 {
 173   GFileOutputStream *stream = G_FILE_OUTPUT_STREAM (source_object);
 174
 175   g_output_stream_clear_pending (G_OUTPUT_STREAM (stream));
 176   if (stream->priv->outstanding_callback)
 177     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 178   g_object_unref (stream);
 179 }
 180
 181 /**
 182  * g_file_output_stream_query_info_async:
 183  * @stream: a #GFileOutputStream.
 184  * @attributes: a file attribute query string.
 185  * @io_priority: the <link linkend="gio-GIOScheduler">I/O priority</link>
 186  *     of the request.
 187  * @cancellable: optional #GCancellable object, %NULL to ignore.
 188  * @callback: callback to call when the request is satisfied
 189  * @user_data: the data to pass to callback function
 190  *
 191  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 192  * @callback will be called with a #GAsyncResult which can be used to
 193  * finish the operation with g_file_output_stream_query_info_finish().
 194  *
 195  * For the synchronous version of this function, see
 196  * g_file_output_stream_query_info().
 197  *
 198  **/
 199 void
 200 g_file_output_stream_query_info_async (GFileOutputStream     *stream,
 201                                           char                 *attributes,
 202                                           int                   io_priority,
 203                                           GCancellable         *cancellable,
 204                                           GAsyncReadyCallback   callback,
 205                                           gpointer              user_data)
 206 {
 207   GFileOutputStreamClass *klass;
 208   GOutputStream *output_stream;
 209   GError *error = NULL;
 210
 211   g_return_if_fail (G_IS_FILE_OUTPUT_STREAM (stream));
 212
 213   output_stream = G_OUTPUT_STREAM (stream);
 214
 215   if (!g_output_stream_set_pending (output_stream, &error))
 216     {
 217       g_simple_async_report_gerror_in_idle (G_OBJECT (stream),
 218                                             callback,
 219                                             user_data,
 220                                             error);
 221       g_error_free (error);
 222       return;
 223     }
 224
 225   klass = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 226
 227   stream->priv->outstanding_callback = callback;
 228   g_object_ref (stream);
 229   klass->query_info_async (stream, attributes, io_priority, cancellable,
 230                               async_ready_callback_wrapper, user_data);
 231 }
 232
 233 /**
 234  * g_file_output_stream_query_info_finish:
 235  * @stream: a #GFileOutputStream.
 236  * @result: a #GAsyncResult.
 237  * @error: a #GError, %NULL to ignore.
 238  *
 239  * Finalizes the asynchronous query started
 240  * by g_file_output_stream_query_info_async().
 241  *
 242  * Returns: A #GFileInfo for the finished query.
 243  **/
 244 GFileInfo *
 245 g_file_output_stream_query_info_finish (GFileOutputStream     *stream,
 246                                            GAsyncResult         *result,
 247                                            GError              **error)
 248 {
 249   GSimpleAsyncResult *simple;
 250   GFileOutputStreamClass *class;
 251
 252   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 253   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 254
 255   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 256     {
 257       simple = G_SIMPLE_ASYNC_RESULT (result);
 258       if (g_simple_async_result_propagate_error (simple, error))
 259         return NULL;
 260     }
 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 its 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 /**
 303  * g_file_output_stream_tell:
 304  * @stream: a #GFileOutputStream.
 305  *
 306  * Gets the current location within the stream.
 307  *
 308  * Returns: a #goffset of the location within the stream.
 309  **/
 310 goffset
 311 g_file_output_stream_tell (GFileOutputStream  *stream)
 312 {
 313   GFileOutputStreamClass *class;
 314   goffset offset;
 315
 316   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), 0);
 317
 318   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 319
 320   offset = 0;
 321   if (class->tell)
 322     offset = class->tell (stream);
 323
 324   return offset;
 325 }
 326
 327 static goffset
 328 g_file_output_stream_seekable_tell (GSeekable *seekable)
 329 {
 330   return g_file_output_stream_tell (G_FILE_OUTPUT_STREAM (seekable));
 331 }
 332
 333 /**
 334  * g_file_output_stream_can_seek:
 335  * @stream: a #GFileOutputStream.
 336  *
 337  * Checks if the stream can be seeked.
 338  *
 339  * Returns: %TRUE if seeking is supported by the stream.
 340  **/
 341 gboolean
 342 g_file_output_stream_can_seek (GFileOutputStream  *stream)
 343 {
 344   GFileOutputStreamClass *class;
 345   gboolean can_seek;
 346
 347   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 348
 349   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 350
 351   can_seek = FALSE;
 352   if (class->seek)
 353     {
 354       can_seek = TRUE;
 355       if (class->can_seek)
 356         can_seek = class->can_seek (stream);
 357     }
 358
 359   return can_seek;
 360 }
 361
 362 static gboolean
 363 g_file_output_stream_seekable_can_seek (GSeekable *seekable)
 364 {
 365   return g_file_output_stream_can_seek (G_FILE_OUTPUT_STREAM (seekable));
 366 }
 367
 368 /**
 369  * g_file_output_stream_seek:
 370  * @stream: a #GFileOutputStream.
 371  * @offset: a #goffset to seek.
 372  * @type: a #GSeekType.
 373  * @cancellable: optional #GCancellable object, %NULL to ignore.
 374  * @error: a #GError, %NULL to ignore.
 375  *
 376  * Seeks to a location in a file output stream.
 377  *
 378  * Returns: %TRUE if the seek was successful. %FALSE otherwise.
 379  **/
 380 gboolean
 381 g_file_output_stream_seek (GFileOutputStream  *stream,
 382                            goffset             offset,
 383                            GSeekType           type,
 384                            GCancellable       *cancellable,
 385                            GError            **error)
 386 {
 387   GFileOutputStreamClass *class;
 388   GOutputStream *output_stream;
 389   gboolean res;
 390
 391   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 392
 393   output_stream = G_OUTPUT_STREAM (stream);
 394   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 395
 396   if (!class->seek)
 397     {
 398       g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 399                    _("Seek not supported on stream"));
 400       return FALSE;
 401     }
 402
 403   if (!g_output_stream_set_pending (output_stream, error))
 404     return FALSE;
 405
 406   if (cancellable)
 407     g_cancellable_push_current (cancellable);
 408
 409   res = class->seek (stream, offset, type, cancellable, error);
 410
 411   if (cancellable)
 412     g_cancellable_pop_current (cancellable);
 413
 414   g_output_stream_clear_pending (output_stream);
 415
 416   return res;
 417 }
 418
 419 static gboolean
 420 g_file_output_stream_seekable_seek (GSeekable  *seekable,
 421                                     goffset     offset,
 422                                     GSeekType   type,
 423                                     GCancellable  *cancellable,
 424                                     GError    **error)
 425 {
 426   return g_file_output_stream_seek (G_FILE_OUTPUT_STREAM (seekable),
 427                                     offset, type, cancellable, error);
 428 }
 429
 430 /**
 431  * g_file_output_stream_can_truncate:
 432  * @stream: a #GFileOutputStream.
 433  *
 434  * Checks if the stream can be truncated.
 435  *
 436  * Returns: %TRUE if stream can be truncated.
 437  **/
 438 gboolean
 439 g_file_output_stream_can_truncate (GFileOutputStream  *stream)
 440 {
 441   GFileOutputStreamClass *class;
 442   gboolean can_truncate;
 443
 444   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 445
 446   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 447
 448   can_truncate = FALSE;
 449   if (class->truncate_fn)
 450     {
 451       can_truncate = TRUE;
 452       if (class->can_truncate)
 453         can_truncate = class->can_truncate (stream);
 454     }
 455
 456   return can_truncate;
 457 }
 458
 459 static gboolean
 460 g_file_output_stream_seekable_can_truncate (GSeekable  *seekable)
 461 {
 462   return g_file_output_stream_can_truncate (G_FILE_OUTPUT_STREAM (seekable));
 463 }
 464
 465 /**
 466  * g_file_output_stream_truncate:
 467  * @stream: a #GFileOutputStream.
 468  * @size: a #goffset to truncate the stream at.
 469  * @cancellable: optional #GCancellable object, %NULL to ignore.
 470  * @error: a #GError, %NULL to ignore.
 471  *
 472  * Truncates a file output stream.
 473  *
 474  * Returns: %TRUE if @stream is truncated successfully.
 475  **/
 476 gboolean
 477 g_file_output_stream_truncate (GFileOutputStream  *stream,
 478                                goffset             size,
 479                                GCancellable       *cancellable,
 480                                GError            **error)
 481 {
 482   GFileOutputStreamClass *class;
 483   GOutputStream *output_stream;
 484   gboolean res;
 485
 486   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 487
 488   output_stream = G_OUTPUT_STREAM (stream);
 489   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 490
 491   if (!class->truncate_fn)
 492     {
 493       g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 494                    _("Truncate not supported on stream"));
 495       return FALSE;
 496     }
 497
 498   if (!g_output_stream_set_pending (output_stream, error))
 499     return FALSE;
 500
 501   if (cancellable)
 502     g_cancellable_push_current (cancellable);
 503
 504   res = class->truncate_fn (stream, size, cancellable, error);
 505
 506   if (cancellable)
 507     g_cancellable_pop_current (cancellable);
 508
 509   g_output_stream_clear_pending (output_stream);
 510
 511   return res;
 512 }
 513
 514 static gboolean
 515 g_file_output_stream_seekable_truncate (GSeekable     *seekable,
 516                                         goffset        size,
 517                                         GCancellable  *cancellable,
 518                                         GError       **error)
 519 {
 520   return g_file_output_stream_truncate (G_FILE_OUTPUT_STREAM (seekable),
 521                                         size, cancellable, error);
 522 }
 523 /********************************************
 524  *   Default implementation of async ops    *
 525  ********************************************/
 526
 527 typedef struct {
 528   char *attributes;
 529   GFileInfo *info;
 530 } QueryInfoAsyncData;
 531
 532 static void
 533 query_info_data_free (QueryInfoAsyncData *data)
 534 {
 535   if (data->info)
 536     g_object_unref (data->info);
 537   g_free (data->attributes);
 538   g_free (data);
 539 }
 540
 541 static void
 542 query_info_async_thread (GSimpleAsyncResult *res,
 543                        GObject *object,
 544                        GCancellable *cancellable)
 545 {
 546   GFileOutputStreamClass *class;
 547   GError *error = NULL;
 548   QueryInfoAsyncData *data;
 549   GFileInfo *info;
 550
 551   data = g_simple_async_result_get_op_res_gpointer (res);
 552
 553   info = NULL;
 554
 555   class = G_FILE_OUTPUT_STREAM_GET_CLASS (object);
 556   if (class->query_info)
 557     info = class->query_info (G_FILE_OUTPUT_STREAM (object), data->attributes, cancellable, &error);
 558   else
 559     g_set_error (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 560                  _("Stream doesn't support query_info"));
 561
 562   if (info == NULL)
 563     {
 564       g_simple_async_result_set_from_error (res, error);
 565       g_error_free (error);
 566     }
 567   else
 568     data->info = info;
 569 }
 570
 571 static void
 572 g_file_output_stream_real_query_info_async (GFileOutputStream     *stream,
 573                                                char                 *attributes,
 574                                                int                   io_priority,
 575                                                GCancellable         *cancellable,
 576                                                GAsyncReadyCallback   callback,
 577                                                gpointer              user_data)
 578 {
 579   GSimpleAsyncResult *res;
 580   QueryInfoAsyncData *data;
 581
 582   data = g_new0 (QueryInfoAsyncData, 1);
 583   data->attributes = g_strdup (attributes);
 584
 585   res = g_simple_async_result_new (G_OBJECT (stream), callback, user_data, g_file_output_stream_real_query_info_async);
 586   g_simple_async_result_set_op_res_gpointer (res, data, (GDestroyNotify)query_info_data_free);
 587
 588   g_simple_async_result_run_in_thread (res, query_info_async_thread, io_priority, cancellable);
 589   g_object_unref (res);
 590 }
 591
 592 static GFileInfo *
 593 g_file_output_stream_real_query_info_finish (GFileOutputStream     *stream,
 594                                                 GAsyncResult         *res,
 595                                                 GError              **error)
 596 {
 597   GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
 598   QueryInfoAsyncData *data;
 599
 600   g_warn_if_fail (g_simple_async_result_get_source_tag (simple) == g_file_output_stream_real_query_info_async);
 601
 602   data = g_simple_async_result_get_op_res_gpointer (simple);
 603   if (data->info)
 604     return g_object_ref (data->info);
 605
 606   return NULL;
 607 }
 608
 609 #define __G_FILE_OUTPUT_STREAM_C__
 610 #include "gioaliasdef.c"