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 "gasyncresult.h"
  29 #include "gtask.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_task_report_error (stream, callback, user_data,
 229                            g_file_output_stream_query_info_async,
 230                            error);
 231       return;
 232     }
 233
 234   klass = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 235
 236   stream->priv->outstanding_callback = callback;
 237   g_object_ref (stream);
 238   klass->query_info_async (stream, attributes, io_priority, cancellable,
 239                            async_ready_callback_wrapper, user_data);
 240 }
 241
 242 /**
 243  * g_file_output_stream_query_info_finish:
 244  * @stream: a #GFileOutputStream.
 245  * @result: a #GAsyncResult.
 246  * @error: a #GError, %NULL to ignore.
 247  *
 248  * Finalizes the asynchronous query started
 249  * by g_file_output_stream_query_info_async().
 250  *
 251  * Returns: (transfer full): A #GFileInfo for the finished query.
 252  **/
 253 GFileInfo *
 254 g_file_output_stream_query_info_finish (GFileOutputStream     *stream,
 255                                            GAsyncResult         *result,
 256                                            GError              **error)
 257 {
 258   GFileOutputStreamClass *class;
 259
 260   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 261   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 262
 263   if (g_async_result_legacy_propagate_error (result, error))
 264     return NULL;
 265   else if (g_async_result_is_tagged (result, g_file_output_stream_query_info_async))
 266     return g_task_propagate_pointer (G_TASK (result), error);
 267
 268   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 269   return class->query_info_finish (stream, result, error);
 270 }
 271
 272 /**
 273  * g_file_output_stream_get_etag:
 274  * @stream: a #GFileOutputStream.
 275  *
 276  * Gets the entity tag for the file when it has been written.
 277  * This must be called after the stream has been written
 278  * and closed, as the etag can change while writing.
 279  *
 280  * Returns: the entity tag for the stream.
 281  **/
 282 char *
 283 g_file_output_stream_get_etag (GFileOutputStream  *stream)
 284 {
 285   GFileOutputStreamClass *class;
 286   GOutputStream *output_stream;
 287   char *etag;
 288
 289   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 290
 291   output_stream = G_OUTPUT_STREAM (stream);
 292
 293   if (!g_output_stream_is_closed (output_stream))
 294     {
 295       g_warning ("stream is not closed yet, can't get etag");
 296       return NULL;
 297     }
 298
 299   etag = NULL;
 300
 301   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 302   if (class->get_etag)
 303     etag = class->get_etag (stream);
 304
 305   return etag;
 306 }
 307
 308 static goffset
 309 g_file_output_stream_tell (GFileOutputStream  *stream)
 310 {
 311   GFileOutputStreamClass *class;
 312   goffset offset;
 313
 314   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), 0);
 315
 316   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 317
 318   offset = 0;
 319   if (class->tell)
 320     offset = class->tell (stream);
 321
 322   return offset;
 323 }
 324
 325 static goffset
 326 g_file_output_stream_seekable_tell (GSeekable *seekable)
 327 {
 328   return g_file_output_stream_tell (G_FILE_OUTPUT_STREAM (seekable));
 329 }
 330
 331 static gboolean
 332 g_file_output_stream_can_seek (GFileOutputStream  *stream)
 333 {
 334   GFileOutputStreamClass *class;
 335   gboolean can_seek;
 336
 337   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 338
 339   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 340
 341   can_seek = FALSE;
 342   if (class->seek)
 343     {
 344       can_seek = TRUE;
 345       if (class->can_seek)
 346         can_seek = class->can_seek (stream);
 347     }
 348
 349   return can_seek;
 350 }
 351
 352 static gboolean
 353 g_file_output_stream_seekable_can_seek (GSeekable *seekable)
 354 {
 355   return g_file_output_stream_can_seek (G_FILE_OUTPUT_STREAM (seekable));
 356 }
 357
 358 static gboolean
 359 g_file_output_stream_seek (GFileOutputStream  *stream,
 360                            goffset             offset,
 361                            GSeekType           type,
 362                            GCancellable       *cancellable,
 363                            GError            **error)
 364 {
 365   GFileOutputStreamClass *class;
 366   GOutputStream *output_stream;
 367   gboolean res;
 368
 369   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 370
 371   output_stream = G_OUTPUT_STREAM (stream);
 372   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 373
 374   if (!class->seek)
 375     {
 376       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 377                            _("Seek not supported on stream"));
 378       return FALSE;
 379     }
 380
 381   if (!g_output_stream_set_pending (output_stream, error))
 382     return FALSE;
 383
 384   if (cancellable)
 385     g_cancellable_push_current (cancellable);
 386
 387   res = class->seek (stream, offset, type, cancellable, error);
 388
 389   if (cancellable)
 390     g_cancellable_pop_current (cancellable);
 391
 392   g_output_stream_clear_pending (output_stream);
 393
 394   return res;
 395 }
 396
 397 static gboolean
 398 g_file_output_stream_seekable_seek (GSeekable  *seekable,
 399                                     goffset     offset,
 400                                     GSeekType   type,
 401                                     GCancellable  *cancellable,
 402                                     GError    **error)
 403 {
 404   return g_file_output_stream_seek (G_FILE_OUTPUT_STREAM (seekable),
 405                                     offset, type, cancellable, error);
 406 }
 407
 408 static gboolean
 409 g_file_output_stream_can_truncate (GFileOutputStream  *stream)
 410 {
 411   GFileOutputStreamClass *class;
 412   gboolean can_truncate;
 413
 414   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 415
 416   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 417
 418   can_truncate = FALSE;
 419   if (class->truncate_fn)
 420     {
 421       can_truncate = TRUE;
 422       if (class->can_truncate)
 423         can_truncate = class->can_truncate (stream);
 424     }
 425
 426   return can_truncate;
 427 }
 428
 429 static gboolean
 430 g_file_output_stream_seekable_can_truncate (GSeekable  *seekable)
 431 {
 432   return g_file_output_stream_can_truncate (G_FILE_OUTPUT_STREAM (seekable));
 433 }
 434
 435 static gboolean
 436 g_file_output_stream_truncate (GFileOutputStream  *stream,
 437                                goffset             size,
 438                                GCancellable       *cancellable,
 439                                GError            **error)
 440 {
 441   GFileOutputStreamClass *class;
 442   GOutputStream *output_stream;
 443   gboolean res;
 444
 445   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 446
 447   output_stream = G_OUTPUT_STREAM (stream);
 448   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 449
 450   if (!class->truncate_fn)
 451     {
 452       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 453                            _("Truncate not supported on stream"));
 454       return FALSE;
 455     }
 456
 457   if (!g_output_stream_set_pending (output_stream, error))
 458     return FALSE;
 459
 460   if (cancellable)
 461     g_cancellable_push_current (cancellable);
 462
 463   res = class->truncate_fn (stream, size, cancellable, error);
 464
 465   if (cancellable)
 466     g_cancellable_pop_current (cancellable);
 467
 468   g_output_stream_clear_pending (output_stream);
 469
 470   return res;
 471 }
 472
 473 static gboolean
 474 g_file_output_stream_seekable_truncate (GSeekable     *seekable,
 475                                         goffset        size,
 476                                         GCancellable  *cancellable,
 477                                         GError       **error)
 478 {
 479   return g_file_output_stream_truncate (G_FILE_OUTPUT_STREAM (seekable),
 480                                         size, cancellable, error);
 481 }
 482 /********************************************
 483  *   Default implementation of async ops    *
 484  ********************************************/
 485
 486 static void
 487 query_info_async_thread (GTask        *task,
 488                          gpointer      source_object,
 489                          gpointer      task_data,
 490                          GCancellable *cancellable)
 491 {
 492   GFileOutputStream *stream = source_object;
 493   const char *attributes = task_data;
 494   GFileOutputStreamClass *class;
 495   GError *error = NULL;
 496   GFileInfo *info = NULL;
 497
 498   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 499   if (class->query_info)
 500     info = class->query_info (stream, attributes, cancellable, &error);
 501   else
 502     g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 503                          _("Stream doesn't support query_info"));
 504
 505   if (info == NULL)
 506     g_task_return_error (task, error);
 507   else
 508     g_task_return_pointer (task, info, g_object_unref);
 509 }
 510
 511 static void
 512 g_file_output_stream_real_query_info_async (GFileOutputStream     *stream,
 513                                                const char           *attributes,
 514                                                int                   io_priority,
 515                                                GCancellable         *cancellable,
 516                                                GAsyncReadyCallback   callback,
 517                                                gpointer              user_data)
 518 {
 519   GTask *task;
 520
 521   task = g_task_new (stream, cancellable, callback, user_data);
 522   g_task_set_task_data (task, g_strdup (attributes), g_free);
 523   g_task_set_priority (task, io_priority);
 524
 525   g_task_run_in_thread (task, query_info_async_thread);
 526   g_object_unref (task);
 527 }
 528
 529 static GFileInfo *
 530 g_file_output_stream_real_query_info_finish (GFileOutputStream     *stream,
 531                                              GAsyncResult         *res,
 532                                              GError              **error)
 533 {
 534   g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
 535
 536   return g_task_propagate_pointer (G_TASK (res), error);
 537 }