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 #include "gioalias.h"
  35
  36 /**
  37  * SECTION:gfileoutputstream
  38  * @short_description: File output streaming operations
  39  * @include: gio/gio.h
  40  * @see_also: #GOutputStream, #GDataOutputStream, #GSeekable
  41  *
  42  * GFileOutputStream provides output streams that write their
  43  * content to a file.
  44  *
  45  * GFileOutputStream implements #GSeekable, which allows the output
  46  * stream to jump to arbitrary positions in the file and to truncate
  47  * the file, provided the filesystem of the file supports these
  48  * operations. In addition to the generic g_seekable_ API,
  49  * GFileOutputStream has its own API for seeking and positioning.
  50  * To find the position of a file output stream, use
  51  * g_file_output_stream_tell(). To find out if a file output
  52  * stream supports seeking, use g_file_output_stream_can_seek().
  53  * To position a file output stream, use g_file_output_stream_seek().
  54  * To find out if a file output stream supports truncating, use
  55  * g_file_output_stream_can_truncate(). To truncate a file output
  56  * stream, use g_file_output_stream_truncate().
  57  **/
  58
  59 static void       g_file_output_stream_seekable_iface_init    (GSeekableIface       *iface);
  60 static goffset    g_file_output_stream_seekable_tell          (GSeekable            *seekable);
  61 static gboolean   g_file_output_stream_seekable_can_seek      (GSeekable            *seekable);
  62 static gboolean   g_file_output_stream_seekable_seek          (GSeekable            *seekable,
  63                                                                goffset               offset,
  64                                                                GSeekType             type,
  65                                                                GCancellable         *cancellable,
  66                                                                GError              **error);
  67 static gboolean   g_file_output_stream_seekable_can_truncate  (GSeekable            *seekable);
  68 static gboolean   g_file_output_stream_seekable_truncate      (GSeekable            *seekable,
  69                                                                goffset               offset,
  70                                                                GCancellable         *cancellable,
  71                                                                GError              **error);
  72 static void       g_file_output_stream_real_query_info_async  (GFileOutputStream    *stream,
  73                                                                const char           *attributes,
  74                                                                int                   io_priority,
  75                                                                GCancellable         *cancellable,
  76                                                                GAsyncReadyCallback   callback,
  77                                                                gpointer              user_data);
  78 static GFileInfo *g_file_output_stream_real_query_info_finish (GFileOutputStream    *stream,
  79                                                                GAsyncResult         *result,
  80                                                                GError              **error);
  81
  82 G_DEFINE_TYPE_WITH_CODE (GFileOutputStream, g_file_output_stream, G_TYPE_OUTPUT_STREAM,
  83                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  84                                                 g_file_output_stream_seekable_iface_init));
  85
  86 struct _GFileOutputStreamPrivate {
  87   GAsyncReadyCallback outstanding_callback;
  88 };
  89
  90 static void
  91 g_file_output_stream_class_init (GFileOutputStreamClass *klass)
  92 {
  93   g_type_class_add_private (klass, sizeof (GFileOutputStreamPrivate));
  94
  95   klass->query_info_async = g_file_output_stream_real_query_info_async;
  96   klass->query_info_finish = g_file_output_stream_real_query_info_finish;
  97 }
  98
  99 static void
 100 g_file_output_stream_seekable_iface_init (GSeekableIface *iface)
 101 {
 102   iface->tell = g_file_output_stream_seekable_tell;
 103   iface->can_seek = g_file_output_stream_seekable_can_seek;
 104   iface->seek = g_file_output_stream_seekable_seek;
 105   iface->can_truncate = g_file_output_stream_seekable_can_truncate;
 106   iface->truncate_fn = g_file_output_stream_seekable_truncate;
 107 }
 108
 109 static void
 110 g_file_output_stream_init (GFileOutputStream *stream)
 111 {
 112   stream->priv = G_TYPE_INSTANCE_GET_PRIVATE (stream,
 113                                               G_TYPE_FILE_OUTPUT_STREAM,
 114                                               GFileOutputStreamPrivate);
 115 }
 116
 117 /**
 118  * g_file_output_stream_query_info:
 119  * @stream: a #GFileOutputStream.
 120  * @attributes: a file attribute query string.
 121  * @cancellable: optional #GCancellable object, %NULL to ignore.
 122  * @error: a #GError, %NULL to ignore.
 123  *
 124  * Queries a file output stream for the given @attributes.
 125  * This function blocks while querying the stream. For the asynchronous
 126  * version of this function, see g_file_output_stream_query_info_async().
 127  * While the stream is blocked, the stream will set the pending flag
 128  * internally, and any other operations on the stream will fail with
 129  * %G_IO_ERROR_PENDING.
 130  *
 131  * Can fail if the stream was already closed (with @error being set to
 132  * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
 133  * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
 134  * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). In
 135  * all cases of failure, %NULL will be returned.
 136  *
 137  * If @cancellable is not %NULL, then the operation can be cancelled by
 138  * triggering the cancellable object from another thread. If the operation
 139  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
 140  * be returned.
 141  *
 142  * Returns: a #GFileInfo for the @stream, or %NULL on error.
 143  **/
 144 GFileInfo *
 145 g_file_output_stream_query_info (GFileOutputStream      *stream,
 146                                     const char             *attributes,
 147                                     GCancellable           *cancellable,
 148                                     GError                **error)
 149 {
 150   GFileOutputStreamClass *class;
 151   GOutputStream *output_stream;
 152   GFileInfo *info;
 153
 154   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 155
 156   output_stream = G_OUTPUT_STREAM (stream);
 157
 158   if (!g_output_stream_set_pending (output_stream, error))
 159     return NULL;
 160
 161   info = NULL;
 162
 163   if (cancellable)
 164     g_cancellable_push_current (cancellable);
 165
 166   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 167   if (class->query_info)
 168     info = class->query_info (stream, attributes, cancellable, error);
 169   else
 170     g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 171                          _("Stream doesn't support query_info"));
 172
 173   if (cancellable)
 174     g_cancellable_pop_current (cancellable);
 175
 176   g_output_stream_clear_pending (output_stream);
 177
 178   return info;
 179 }
 180
 181 static void
 182 async_ready_callback_wrapper (GObject *source_object,
 183                               GAsyncResult *res,
 184                               gpointer      user_data)
 185 {
 186   GFileOutputStream *stream = G_FILE_OUTPUT_STREAM (source_object);
 187
 188   g_output_stream_clear_pending (G_OUTPUT_STREAM (stream));
 189   if (stream->priv->outstanding_callback)
 190     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 191   g_object_unref (stream);
 192 }
 193
 194 /**
 195  * g_file_output_stream_query_info_async:
 196  * @stream: a #GFileOutputStream.
 197  * @attributes: a file attribute query string.
 198  * @io_priority: the <link linkend="gio-GIOScheduler">I/O priority</link>
 199  *     of the request.
 200  * @cancellable: optional #GCancellable object, %NULL to ignore.
 201  * @callback: callback to call when the request is satisfied
 202  * @user_data: the data to pass to callback function
 203  *
 204  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 205  * @callback will be called with a #GAsyncResult which can be used to
 206  * finish the operation with g_file_output_stream_query_info_finish().
 207  *
 208  * For the synchronous version of this function, see
 209  * g_file_output_stream_query_info().
 210  *
 211  **/
 212 void
 213 g_file_output_stream_query_info_async (GFileOutputStream     *stream,
 214                                           const char           *attributes,
 215                                           int                   io_priority,
 216                                           GCancellable         *cancellable,
 217                                           GAsyncReadyCallback   callback,
 218                                           gpointer              user_data)
 219 {
 220   GFileOutputStreamClass *klass;
 221   GOutputStream *output_stream;
 222   GError *error = NULL;
 223
 224   g_return_if_fail (G_IS_FILE_OUTPUT_STREAM (stream));
 225
 226   output_stream = G_OUTPUT_STREAM (stream);
 227
 228   if (!g_output_stream_set_pending (output_stream, &error))
 229     {
 230       g_simple_async_report_gerror_in_idle (G_OBJECT (stream),
 231                                             callback,
 232                                             user_data,
 233                                             error);
 234       g_error_free (error);
 235       return;
 236     }
 237
 238   klass = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 239
 240   stream->priv->outstanding_callback = callback;
 241   g_object_ref (stream);
 242   klass->query_info_async (stream, attributes, io_priority, cancellable,
 243                               async_ready_callback_wrapper, user_data);
 244 }
 245
 246 /**
 247  * g_file_output_stream_query_info_finish:
 248  * @stream: a #GFileOutputStream.
 249  * @result: a #GAsyncResult.
 250  * @error: a #GError, %NULL to ignore.
 251  *
 252  * Finalizes the asynchronous query started
 253  * by g_file_output_stream_query_info_async().
 254  *
 255  * Returns: A #GFileInfo for the finished query.
 256  **/
 257 GFileInfo *
 258 g_file_output_stream_query_info_finish (GFileOutputStream     *stream,
 259                                            GAsyncResult         *result,
 260                                            GError              **error)
 261 {
 262   GSimpleAsyncResult *simple;
 263   GFileOutputStreamClass *class;
 264
 265   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 266   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 267
 268   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 269     {
 270       simple = G_SIMPLE_ASYNC_RESULT (result);
 271       if (g_simple_async_result_propagate_error (simple, error))
 272         return NULL;
 273     }
 274
 275   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 276   return class->query_info_finish (stream, result, error);
 277 }
 278
 279 /**
 280  * g_file_output_stream_get_etag:
 281  * @stream: a #GFileOutputStream.
 282  *
 283  * Gets the entity tag for the file when it has been written.
 284  * This must be called after the stream has been written
 285  * and closed, as the etag can change while writing.
 286  *
 287  * Returns: the entity tag for the stream.
 288  **/
 289 char *
 290 g_file_output_stream_get_etag (GFileOutputStream  *stream)
 291 {
 292   GFileOutputStreamClass *class;
 293   GOutputStream *output_stream;
 294   char *etag;
 295
 296   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 297
 298   output_stream = G_OUTPUT_STREAM (stream);
 299
 300   if (!g_output_stream_is_closed (output_stream))
 301     {
 302       g_warning ("stream is not closed yet, can't get etag");
 303       return NULL;
 304     }
 305
 306   etag = NULL;
 307
 308   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 309   if (class->get_etag)
 310     etag = class->get_etag (stream);
 311
 312   return etag;
 313 }
 314
 315 static goffset
 316 g_file_output_stream_tell (GFileOutputStream  *stream)
 317 {
 318   GFileOutputStreamClass *class;
 319   goffset offset;
 320
 321   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), 0);
 322
 323   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 324
 325   offset = 0;
 326   if (class->tell)
 327     offset = class->tell (stream);
 328
 329   return offset;
 330 }
 331
 332 static goffset
 333 g_file_output_stream_seekable_tell (GSeekable *seekable)
 334 {
 335   return g_file_output_stream_tell (G_FILE_OUTPUT_STREAM (seekable));
 336 }
 337
 338 static gboolean
 339 g_file_output_stream_can_seek (GFileOutputStream  *stream)
 340 {
 341   GFileOutputStreamClass *class;
 342   gboolean can_seek;
 343
 344   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 345
 346   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 347
 348   can_seek = FALSE;
 349   if (class->seek)
 350     {
 351       can_seek = TRUE;
 352       if (class->can_seek)
 353         can_seek = class->can_seek (stream);
 354     }
 355
 356   return can_seek;
 357 }
 358
 359 static gboolean
 360 g_file_output_stream_seekable_can_seek (GSeekable *seekable)
 361 {
 362   return g_file_output_stream_can_seek (G_FILE_OUTPUT_STREAM (seekable));
 363 }
 364
 365 static gboolean
 366 g_file_output_stream_seek (GFileOutputStream  *stream,
 367                            goffset             offset,
 368                            GSeekType           type,
 369                            GCancellable       *cancellable,
 370                            GError            **error)
 371 {
 372   GFileOutputStreamClass *class;
 373   GOutputStream *output_stream;
 374   gboolean res;
 375
 376   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 377
 378   output_stream = G_OUTPUT_STREAM (stream);
 379   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 380
 381   if (!class->seek)
 382     {
 383       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 384                            _("Seek not supported on stream"));
 385       return FALSE;
 386     }
 387
 388   if (!g_output_stream_set_pending (output_stream, error))
 389     return FALSE;
 390
 391   if (cancellable)
 392     g_cancellable_push_current (cancellable);
 393
 394   res = class->seek (stream, offset, type, cancellable, error);
 395
 396   if (cancellable)
 397     g_cancellable_pop_current (cancellable);
 398
 399   g_output_stream_clear_pending (output_stream);
 400
 401   return res;
 402 }
 403
 404 static gboolean
 405 g_file_output_stream_seekable_seek (GSeekable  *seekable,
 406                                     goffset     offset,
 407                                     GSeekType   type,
 408                                     GCancellable  *cancellable,
 409                                     GError    **error)
 410 {
 411   return g_file_output_stream_seek (G_FILE_OUTPUT_STREAM (seekable),
 412                                     offset, type, cancellable, error);
 413 }
 414
 415 static gboolean
 416 g_file_output_stream_can_truncate (GFileOutputStream  *stream)
 417 {
 418   GFileOutputStreamClass *class;
 419   gboolean can_truncate;
 420
 421   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 422
 423   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 424
 425   can_truncate = FALSE;
 426   if (class->truncate_fn)
 427     {
 428       can_truncate = TRUE;
 429       if (class->can_truncate)
 430         can_truncate = class->can_truncate (stream);
 431     }
 432
 433   return can_truncate;
 434 }
 435
 436 static gboolean
 437 g_file_output_stream_seekable_can_truncate (GSeekable  *seekable)
 438 {
 439   return g_file_output_stream_can_truncate (G_FILE_OUTPUT_STREAM (seekable));
 440 }
 441
 442 static gboolean
 443 g_file_output_stream_truncate (GFileOutputStream  *stream,
 444                                goffset             size,
 445                                GCancellable       *cancellable,
 446                                GError            **error)
 447 {
 448   GFileOutputStreamClass *class;
 449   GOutputStream *output_stream;
 450   gboolean res;
 451
 452   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 453
 454   output_stream = G_OUTPUT_STREAM (stream);
 455   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 456
 457   if (!class->truncate_fn)
 458     {
 459       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 460                            _("Truncate not supported on stream"));
 461       return FALSE;
 462     }
 463
 464   if (!g_output_stream_set_pending (output_stream, error))
 465     return FALSE;
 466
 467   if (cancellable)
 468     g_cancellable_push_current (cancellable);
 469
 470   res = class->truncate_fn (stream, size, cancellable, error);
 471
 472   if (cancellable)
 473     g_cancellable_pop_current (cancellable);
 474
 475   g_output_stream_clear_pending (output_stream);
 476
 477   return res;
 478 }
 479
 480 static gboolean
 481 g_file_output_stream_seekable_truncate (GSeekable     *seekable,
 482                                         goffset        size,
 483                                         GCancellable  *cancellable,
 484                                         GError       **error)
 485 {
 486   return g_file_output_stream_truncate (G_FILE_OUTPUT_STREAM (seekable),
 487                                         size, cancellable, error);
 488 }
 489 /********************************************
 490  *   Default implementation of async ops    *
 491  ********************************************/
 492
 493 typedef struct {
 494   char *attributes;
 495   GFileInfo *info;
 496 } QueryInfoAsyncData;
 497
 498 static void
 499 query_info_data_free (QueryInfoAsyncData *data)
 500 {
 501   if (data->info)
 502     g_object_unref (data->info);
 503   g_free (data->attributes);
 504   g_free (data);
 505 }
 506
 507 static void
 508 query_info_async_thread (GSimpleAsyncResult *res,
 509                        GObject *object,
 510                        GCancellable *cancellable)
 511 {
 512   GFileOutputStreamClass *class;
 513   GError *error = NULL;
 514   QueryInfoAsyncData *data;
 515   GFileInfo *info;
 516
 517   data = g_simple_async_result_get_op_res_gpointer (res);
 518
 519   info = NULL;
 520
 521   class = G_FILE_OUTPUT_STREAM_GET_CLASS (object);
 522   if (class->query_info)
 523     info = class->query_info (G_FILE_OUTPUT_STREAM (object), data->attributes, cancellable, &error);
 524   else
 525     g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 526                          _("Stream doesn't support query_info"));
 527
 528   if (info == NULL)
 529     {
 530       g_simple_async_result_set_from_error (res, error);
 531       g_error_free (error);
 532     }
 533   else
 534     data->info = info;
 535 }
 536
 537 static void
 538 g_file_output_stream_real_query_info_async (GFileOutputStream     *stream,
 539                                                const char           *attributes,
 540                                                int                   io_priority,
 541                                                GCancellable         *cancellable,
 542                                                GAsyncReadyCallback   callback,
 543                                                gpointer              user_data)
 544 {
 545   GSimpleAsyncResult *res;
 546   QueryInfoAsyncData *data;
 547
 548   data = g_new0 (QueryInfoAsyncData, 1);
 549   data->attributes = g_strdup (attributes);
 550
 551   res = g_simple_async_result_new (G_OBJECT (stream), callback, user_data, g_file_output_stream_real_query_info_async);
 552   g_simple_async_result_set_op_res_gpointer (res, data, (GDestroyNotify)query_info_data_free);
 553
 554   g_simple_async_result_run_in_thread (res, query_info_async_thread, io_priority, cancellable);
 555   g_object_unref (res);
 556 }
 557
 558 static GFileInfo *
 559 g_file_output_stream_real_query_info_finish (GFileOutputStream     *stream,
 560                                                 GAsyncResult         *res,
 561                                                 GError              **error)
 562 {
 563   GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
 564   QueryInfoAsyncData *data;
 565
 566   g_warn_if_fail (g_simple_async_result_get_source_tag (simple) == g_file_output_stream_real_query_info_async);
 567
 568   data = g_simple_async_result_get_op_res_gpointer (simple);
 569   if (data->info)
 570     return g_object_ref (data->info);
 571
 572   return NULL;
 573 }
 574
 575 #define __G_FILE_OUTPUT_STREAM_C__
 576 #include "gioaliasdef.c"