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 "gasyncresult.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 G_DEFINE_TYPE_WITH_CODE (GFileOutputStream, g_file_output_stream, G_TYPE_OUTPUT_STREAM,
  81                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  82                                                 g_file_output_stream_seekable_iface_init));
  83
  84 struct _GFileOutputStreamPrivate {
  85   GAsyncReadyCallback outstanding_callback;
  86 };
  87
  88 static void
  89 g_file_output_stream_class_init (GFileOutputStreamClass *klass)
  90 {
  91   g_type_class_add_private (klass, sizeof (GFileOutputStreamPrivate));
  92
  93   klass->query_info_async = g_file_output_stream_real_query_info_async;
  94   klass->query_info_finish = g_file_output_stream_real_query_info_finish;
  95 }
  96
  97 static void
  98 g_file_output_stream_seekable_iface_init (GSeekableIface *iface)
  99 {
 100   iface->tell = g_file_output_stream_seekable_tell;
 101   iface->can_seek = g_file_output_stream_seekable_can_seek;
 102   iface->seek = g_file_output_stream_seekable_seek;
 103   iface->can_truncate = g_file_output_stream_seekable_can_truncate;
 104   iface->truncate_fn = g_file_output_stream_seekable_truncate;
 105 }
 106
 107 static void
 108 g_file_output_stream_init (GFileOutputStream *stream)
 109 {
 110   stream->priv = G_TYPE_INSTANCE_GET_PRIVATE (stream,
 111                                               G_TYPE_FILE_OUTPUT_STREAM,
 112                                               GFileOutputStreamPrivate);
 113 }
 114
 115 /**
 116  * g_file_output_stream_query_info:
 117  * @stream: a #GFileOutputStream.
 118  * @attributes: a file attribute query string.
 119  * @cancellable: optional #GCancellable object, %NULL to ignore.
 120  * @error: a #GError, %NULL to ignore.
 121  *
 122  * Queries a file output stream for the given @attributes.
 123  * This function blocks while querying the stream. For the asynchronous
 124  * version of this function, see g_file_output_stream_query_info_async().
 125  * While the stream is blocked, the stream will set the pending flag
 126  * internally, and any other operations on the stream will fail with
 127  * %G_IO_ERROR_PENDING.
 128  *
 129  * Can fail if the stream was already closed (with @error being set to
 130  * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
 131  * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
 132  * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). In
 133  * all cases of failure, %NULL will be returned.
 134  *
 135  * If @cancellable is not %NULL, then the operation can be cancelled by
 136  * triggering the cancellable object from another thread. If the operation
 137  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
 138  * be returned.
 139  *
 140  * Returns: (transfer full): a #GFileInfo for the @stream, or %NULL on error.
 141  **/
 142 GFileInfo *
 143 g_file_output_stream_query_info (GFileOutputStream      *stream,
 144                                     const char             *attributes,
 145                                     GCancellable           *cancellable,
 146                                     GError                **error)
 147 {
 148   GFileOutputStreamClass *class;
 149   GOutputStream *output_stream;
 150   GFileInfo *info;
 151
 152   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 153
 154   output_stream = G_OUTPUT_STREAM (stream);
 155
 156   if (!g_output_stream_set_pending (output_stream, error))
 157     return NULL;
 158
 159   info = NULL;
 160
 161   if (cancellable)
 162     g_cancellable_push_current (cancellable);
 163
 164   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 165   if (class->query_info)
 166     info = class->query_info (stream, attributes, cancellable, error);
 167   else
 168     g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 169                          _("Stream doesn't support query_info"));
 170
 171   if (cancellable)
 172     g_cancellable_pop_current (cancellable);
 173
 174   g_output_stream_clear_pending (output_stream);
 175
 176   return info;
 177 }
 178
 179 static void
 180 async_ready_callback_wrapper (GObject *source_object,
 181                               GAsyncResult *res,
 182                               gpointer      user_data)
 183 {
 184   GFileOutputStream *stream = G_FILE_OUTPUT_STREAM (source_object);
 185
 186   g_output_stream_clear_pending (G_OUTPUT_STREAM (stream));
 187   if (stream->priv->outstanding_callback)
 188     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 189   g_object_unref (stream);
 190 }
 191
 192 /**
 193  * g_file_output_stream_query_info_async:
 194  * @stream: a #GFileOutputStream.
 195  * @attributes: a file attribute query string.
 196  * @io_priority: the <link linkend="gio-GIOScheduler">I/O priority</link>
 197  *     of the request.
 198  * @cancellable: optional #GCancellable object, %NULL to ignore.
 199  * @callback: callback to call when the request is satisfied
 200  * @user_data: the data to pass to callback function
 201  *
 202  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 203  * @callback will be called with a #GAsyncResult which can be used to
 204  * finish the operation with g_file_output_stream_query_info_finish().
 205  *
 206  * For the synchronous version of this function, see
 207  * g_file_output_stream_query_info().
 208  *
 209  **/
 210 void
 211 g_file_output_stream_query_info_async (GFileOutputStream     *stream,
 212                                           const char           *attributes,
 213                                           int                   io_priority,
 214                                           GCancellable         *cancellable,
 215                                           GAsyncReadyCallback   callback,
 216                                           gpointer              user_data)
 217 {
 218   GFileOutputStreamClass *klass;
 219   GOutputStream *output_stream;
 220   GError *error = NULL;
 221
 222   g_return_if_fail (G_IS_FILE_OUTPUT_STREAM (stream));
 223
 224   output_stream = G_OUTPUT_STREAM (stream);
 225
 226   if (!g_output_stream_set_pending (output_stream, &error))
 227     {
 228       g_simple_async_report_gerror_in_idle (G_OBJECT (stream),
 229                                             callback,
 230                                             user_data,
 231                                             error);
 232       g_error_free (error);
 233       return;
 234     }
 235
 236   klass = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 237
 238   stream->priv->outstanding_callback = callback;
 239   g_object_ref (stream);
 240   klass->query_info_async (stream, attributes, io_priority, cancellable,
 241                               async_ready_callback_wrapper, user_data);
 242 }
 243
 244 /**
 245  * g_file_output_stream_query_info_finish:
 246  * @stream: a #GFileOutputStream.
 247  * @result: a #GAsyncResult.
 248  * @error: a #GError, %NULL to ignore.
 249  *
 250  * Finalizes the asynchronous query started
 251  * by g_file_output_stream_query_info_async().
 252  *
 253  * Returns: (transfer full): A #GFileInfo for the finished query.
 254  **/
 255 GFileInfo *
 256 g_file_output_stream_query_info_finish (GFileOutputStream     *stream,
 257                                            GAsyncResult         *result,
 258                                            GError              **error)
 259 {
 260   GSimpleAsyncResult *simple;
 261   GFileOutputStreamClass *class;
 262
 263   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 264   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 265
 266   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 267     {
 268       simple = G_SIMPLE_ASYNC_RESULT (result);
 269       if (g_simple_async_result_propagate_error (simple, error))
 270         return NULL;
 271     }
 272
 273   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 274   return class->query_info_finish (stream, result, error);
 275 }
 276
 277 /**
 278  * g_file_output_stream_get_etag:
 279  * @stream: a #GFileOutputStream.
 280  *
 281  * Gets the entity tag for the file when it has been written.
 282  * This must be called after the stream has been written
 283  * and closed, as the etag can change while writing.
 284  *
 285  * Returns: the entity tag for the stream.
 286  **/
 287 char *
 288 g_file_output_stream_get_etag (GFileOutputStream  *stream)
 289 {
 290   GFileOutputStreamClass *class;
 291   GOutputStream *output_stream;
 292   char *etag;
 293
 294   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 295
 296   output_stream = G_OUTPUT_STREAM (stream);
 297
 298   if (!g_output_stream_is_closed (output_stream))
 299     {
 300       g_warning ("stream is not closed yet, can't get etag");
 301       return NULL;
 302     }
 303
 304   etag = NULL;
 305
 306   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 307   if (class->get_etag)
 308     etag = class->get_etag (stream);
 309
 310   return etag;
 311 }
 312
 313 static goffset
 314 g_file_output_stream_tell (GFileOutputStream  *stream)
 315 {
 316   GFileOutputStreamClass *class;
 317   goffset offset;
 318
 319   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), 0);
 320
 321   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 322
 323   offset = 0;
 324   if (class->tell)
 325     offset = class->tell (stream);
 326
 327   return offset;
 328 }
 329
 330 static goffset
 331 g_file_output_stream_seekable_tell (GSeekable *seekable)
 332 {
 333   return g_file_output_stream_tell (G_FILE_OUTPUT_STREAM (seekable));
 334 }
 335
 336 static gboolean
 337 g_file_output_stream_can_seek (GFileOutputStream  *stream)
 338 {
 339   GFileOutputStreamClass *class;
 340   gboolean can_seek;
 341
 342   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 343
 344   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 345
 346   can_seek = FALSE;
 347   if (class->seek)
 348     {
 349       can_seek = TRUE;
 350       if (class->can_seek)
 351         can_seek = class->can_seek (stream);
 352     }
 353
 354   return can_seek;
 355 }
 356
 357 static gboolean
 358 g_file_output_stream_seekable_can_seek (GSeekable *seekable)
 359 {
 360   return g_file_output_stream_can_seek (G_FILE_OUTPUT_STREAM (seekable));
 361 }
 362
 363 static gboolean
 364 g_file_output_stream_seek (GFileOutputStream  *stream,
 365                            goffset             offset,
 366                            GSeekType           type,
 367                            GCancellable       *cancellable,
 368                            GError            **error)
 369 {
 370   GFileOutputStreamClass *class;
 371   GOutputStream *output_stream;
 372   gboolean res;
 373
 374   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 375
 376   output_stream = G_OUTPUT_STREAM (stream);
 377   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 378
 379   if (!class->seek)
 380     {
 381       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 382                            _("Seek not supported on stream"));
 383       return FALSE;
 384     }
 385
 386   if (!g_output_stream_set_pending (output_stream, error))
 387     return FALSE;
 388
 389   if (cancellable)
 390     g_cancellable_push_current (cancellable);
 391
 392   res = class->seek (stream, offset, type, cancellable, error);
 393
 394   if (cancellable)
 395     g_cancellable_pop_current (cancellable);
 396
 397   g_output_stream_clear_pending (output_stream);
 398
 399   return res;
 400 }
 401
 402 static gboolean
 403 g_file_output_stream_seekable_seek (GSeekable  *seekable,
 404                                     goffset     offset,
 405                                     GSeekType   type,
 406                                     GCancellable  *cancellable,
 407                                     GError    **error)
 408 {
 409   return g_file_output_stream_seek (G_FILE_OUTPUT_STREAM (seekable),
 410                                     offset, type, cancellable, error);
 411 }
 412
 413 static gboolean
 414 g_file_output_stream_can_truncate (GFileOutputStream  *stream)
 415 {
 416   GFileOutputStreamClass *class;
 417   gboolean can_truncate;
 418
 419   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 420
 421   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 422
 423   can_truncate = FALSE;
 424   if (class->truncate_fn)
 425     {
 426       can_truncate = TRUE;
 427       if (class->can_truncate)
 428         can_truncate = class->can_truncate (stream);
 429     }
 430
 431   return can_truncate;
 432 }
 433
 434 static gboolean
 435 g_file_output_stream_seekable_can_truncate (GSeekable  *seekable)
 436 {
 437   return g_file_output_stream_can_truncate (G_FILE_OUTPUT_STREAM (seekable));
 438 }
 439
 440 static gboolean
 441 g_file_output_stream_truncate (GFileOutputStream  *stream,
 442                                goffset             size,
 443                                GCancellable       *cancellable,
 444                                GError            **error)
 445 {
 446   GFileOutputStreamClass *class;
 447   GOutputStream *output_stream;
 448   gboolean res;
 449
 450   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 451
 452   output_stream = G_OUTPUT_STREAM (stream);
 453   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 454
 455   if (!class->truncate_fn)
 456     {
 457       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 458                            _("Truncate not supported on stream"));
 459       return FALSE;
 460     }
 461
 462   if (!g_output_stream_set_pending (output_stream, error))
 463     return FALSE;
 464
 465   if (cancellable)
 466     g_cancellable_push_current (cancellable);
 467
 468   res = class->truncate_fn (stream, size, cancellable, error);
 469
 470   if (cancellable)
 471     g_cancellable_pop_current (cancellable);
 472
 473   g_output_stream_clear_pending (output_stream);
 474
 475   return res;
 476 }
 477
 478 static gboolean
 479 g_file_output_stream_seekable_truncate (GSeekable     *seekable,
 480                                         goffset        size,
 481                                         GCancellable  *cancellable,
 482                                         GError       **error)
 483 {
 484   return g_file_output_stream_truncate (G_FILE_OUTPUT_STREAM (seekable),
 485                                         size, cancellable, error);
 486 }
 487 /********************************************
 488  *   Default implementation of async ops    *
 489  ********************************************/
 490
 491 typedef struct {
 492   char *attributes;
 493   GFileInfo *info;
 494 } QueryInfoAsyncData;
 495
 496 static void
 497 query_info_data_free (QueryInfoAsyncData *data)
 498 {
 499   if (data->info)
 500     g_object_unref (data->info);
 501   g_free (data->attributes);
 502   g_free (data);
 503 }
 504
 505 static void
 506 query_info_async_thread (GSimpleAsyncResult *res,
 507                        GObject *object,
 508                        GCancellable *cancellable)
 509 {
 510   GFileOutputStreamClass *class;
 511   GError *error = NULL;
 512   QueryInfoAsyncData *data;
 513   GFileInfo *info;
 514
 515   data = g_simple_async_result_get_op_res_gpointer (res);
 516
 517   info = NULL;
 518
 519   class = G_FILE_OUTPUT_STREAM_GET_CLASS (object);
 520   if (class->query_info)
 521     info = class->query_info (G_FILE_OUTPUT_STREAM (object), data->attributes, cancellable, &error);
 522   else
 523     g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 524                          _("Stream doesn't support query_info"));
 525
 526   if (info == NULL)
 527     {
 528       g_simple_async_result_set_from_error (res, error);
 529       g_error_free (error);
 530     }
 531   else
 532     data->info = info;
 533 }
 534
 535 static void
 536 g_file_output_stream_real_query_info_async (GFileOutputStream     *stream,
 537                                                const char           *attributes,
 538                                                int                   io_priority,
 539                                                GCancellable         *cancellable,
 540                                                GAsyncReadyCallback   callback,
 541                                                gpointer              user_data)
 542 {
 543   GSimpleAsyncResult *res;
 544   QueryInfoAsyncData *data;
 545
 546   data = g_new0 (QueryInfoAsyncData, 1);
 547   data->attributes = g_strdup (attributes);
 548
 549   res = g_simple_async_result_new (G_OBJECT (stream), callback, user_data, g_file_output_stream_real_query_info_async);
 550   g_simple_async_result_set_op_res_gpointer (res, data, (GDestroyNotify)query_info_data_free);
 551
 552   g_simple_async_result_run_in_thread (res, query_info_async_thread, io_priority, cancellable);
 553   g_object_unref (res);
 554 }
 555
 556 static GFileInfo *
 557 g_file_output_stream_real_query_info_finish (GFileOutputStream     *stream,
 558                                                 GAsyncResult         *res,
 559                                                 GError              **error)
 560 {
 561   GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
 562   QueryInfoAsyncData *data;
 563
 564   g_warn_if_fail (g_simple_async_result_get_source_tag (simple) == g_file_output_stream_real_query_info_async);
 565
 566   data = g_simple_async_result_get_op_res_gpointer (simple);
 567   if (data->info)
 568     return g_object_ref (data->info);
 569
 570   return NULL;
 571 }