gio/gfileoutputstream.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright (C) 2006-2007 Red Hat, Inc.
   4  *
   5  * SPDX-License-Identifier: LGPL-2.1-or-later
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General
  18  * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
  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 struct _GFileOutputStreamPrivate {
  81   GAsyncReadyCallback outstanding_callback;
  82 };
  83
  84 G_DEFINE_TYPE_WITH_CODE (GFileOutputStream, g_file_output_stream, G_TYPE_OUTPUT_STREAM,
  85                          G_ADD_PRIVATE (GFileOutputStream)
  86                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  87                                                 g_file_output_stream_seekable_iface_init));
  88
  89 static void
  90 g_file_output_stream_class_init (GFileOutputStreamClass *klass)
  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_file_output_stream_get_instance_private (stream);
 110 }
 111
 112 /**
 113  * g_file_output_stream_query_info:
 114  * @stream: a #GFileOutputStream.
 115  * @attributes: a file attribute query string.
 116  * @cancellable: optional #GCancellable object, %NULL to ignore.
 117  * @error: a #GError, %NULL to ignore.
 118  *
 119  * Queries a file output stream for the given @attributes.
 120  * This function blocks while querying the stream. For the asynchronous
 121  * version of this function, see g_file_output_stream_query_info_async().
 122  * While the stream is blocked, the stream will set the pending flag
 123  * internally, and any other operations on the stream will fail with
 124  * %G_IO_ERROR_PENDING.
 125  *
 126  * Can fail if the stream was already closed (with @error being set to
 127  * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
 128  * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
 129  * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). In
 130  * all cases of failure, %NULL will be returned.
 131  *
 132  * If @cancellable is not %NULL, then the operation can be cancelled by
 133  * triggering the cancellable object from another thread. If the operation
 134  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
 135  * be returned.
 136  *
 137  * Returns: (transfer full): a #GFileInfo for the @stream, or %NULL on error.
 138  **/
 139 GFileInfo *
 140 g_file_output_stream_query_info (GFileOutputStream      *stream,
 141                                     const char             *attributes,
 142                                     GCancellable           *cancellable,
 143                                     GError                **error)
 144 {
 145   GFileOutputStreamClass *class;
 146   GOutputStream *output_stream;
 147   GFileInfo *info;
 148
 149   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 150
 151   output_stream = G_OUTPUT_STREAM (stream);
 152
 153   if (!g_output_stream_set_pending (output_stream, error))
 154     return NULL;
 155
 156   info = NULL;
 157
 158   if (cancellable)
 159     g_cancellable_push_current (cancellable);
 160
 161   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 162   if (class->query_info)
 163     info = class->query_info (stream, attributes, cancellable, error);
 164   else
 165     g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 166                          _("Stream doesn’t support query_info"));
 167
 168   if (cancellable)
 169     g_cancellable_pop_current (cancellable);
 170
 171   g_output_stream_clear_pending (output_stream);
 172
 173   return info;
 174 }
 175
 176 static void
 177 async_ready_callback_wrapper (GObject *source_object,
 178                               GAsyncResult *res,
 179                               gpointer      user_data)
 180 {
 181   GFileOutputStream *stream = G_FILE_OUTPUT_STREAM (source_object);
 182
 183   g_output_stream_clear_pending (G_OUTPUT_STREAM (stream));
 184   if (stream->priv->outstanding_callback)
 185     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 186   g_object_unref (stream);
 187 }
 188
 189 /**
 190  * g_file_output_stream_query_info_async:
 191  * @stream: a #GFileOutputStream.
 192  * @attributes: a file attribute query string.
 193  * @io_priority: the [I/O priority][gio-GIOScheduler] of the request
 194  * @cancellable: optional #GCancellable object, %NULL to ignore.
 195  * @callback: callback to call when the request is satisfied
 196  * @user_data: the data to pass to callback function
 197  *
 198  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 199  * @callback will be called with a #GAsyncResult which can be used to
 200  * finish the operation with g_file_output_stream_query_info_finish().
 201  *
 202  * For the synchronous version of this function, see
 203  * g_file_output_stream_query_info().
 204  *
 205  **/
 206 void
 207 g_file_output_stream_query_info_async (GFileOutputStream     *stream,
 208                                           const char           *attributes,
 209                                           int                   io_priority,
 210                                           GCancellable         *cancellable,
 211                                           GAsyncReadyCallback   callback,
 212                                           gpointer              user_data)
 213 {
 214   GFileOutputStreamClass *klass;
 215   GOutputStream *output_stream;
 216   GError *error = NULL;
 217
 218   g_return_if_fail (G_IS_FILE_OUTPUT_STREAM (stream));
 219
 220   output_stream = G_OUTPUT_STREAM (stream);
 221
 222   if (!g_output_stream_set_pending (output_stream, &error))
 223     {
 224       g_task_report_error (stream, callback, user_data,
 225                            g_file_output_stream_query_info_async,
 226                            error);
 227       return;
 228     }
 229
 230   klass = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 231
 232   stream->priv->outstanding_callback = callback;
 233   g_object_ref (stream);
 234   klass->query_info_async (stream, attributes, io_priority, cancellable,
 235                            async_ready_callback_wrapper, user_data);
 236 }
 237
 238 /**
 239  * g_file_output_stream_query_info_finish:
 240  * @stream: a #GFileOutputStream.
 241  * @result: a #GAsyncResult.
 242  * @error: a #GError, %NULL to ignore.
 243  *
 244  * Finalizes the asynchronous query started
 245  * by g_file_output_stream_query_info_async().
 246  *
 247  * Returns: (transfer full): A #GFileInfo for the finished query.
 248  **/
 249 GFileInfo *
 250 g_file_output_stream_query_info_finish (GFileOutputStream     *stream,
 251                                            GAsyncResult         *result,
 252                                            GError              **error)
 253 {
 254   GFileOutputStreamClass *class;
 255
 256   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 257   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 258
 259   if (g_async_result_legacy_propagate_error (result, error))
 260     return NULL;
 261   else if (g_async_result_is_tagged (result, g_file_output_stream_query_info_async))
 262     return g_task_propagate_pointer (G_TASK (result), error);
 263
 264   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 265   return class->query_info_finish (stream, result, error);
 266 }
 267
 268 /**
 269  * g_file_output_stream_get_etag:
 270  * @stream: a #GFileOutputStream.
 271  *
 272  * Gets the entity tag for the file when it has been written.
 273  * This must be called after the stream has been written
 274  * and closed, as the etag can change while writing.
 275  *
 276  * Returns: (nullable) (transfer full): the entity tag for the stream.
 277  **/
 278 char *
 279 g_file_output_stream_get_etag (GFileOutputStream  *stream)
 280 {
 281   GFileOutputStreamClass *class;
 282   GOutputStream *output_stream;
 283   char *etag;
 284
 285   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), NULL);
 286
 287   output_stream = G_OUTPUT_STREAM (stream);
 288
 289   if (!g_output_stream_is_closed (output_stream))
 290     {
 291       g_warning ("stream is not closed yet, can't get etag");
 292       return NULL;
 293     }
 294
 295   etag = NULL;
 296
 297   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 298   if (class->get_etag)
 299     etag = class->get_etag (stream);
 300
 301   return etag;
 302 }
 303
 304 static goffset
 305 g_file_output_stream_tell (GFileOutputStream  *stream)
 306 {
 307   GFileOutputStreamClass *class;
 308   goffset offset;
 309
 310   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), 0);
 311
 312   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 313
 314   offset = 0;
 315   if (class->tell)
 316     offset = class->tell (stream);
 317
 318   return offset;
 319 }
 320
 321 static goffset
 322 g_file_output_stream_seekable_tell (GSeekable *seekable)
 323 {
 324   return g_file_output_stream_tell (G_FILE_OUTPUT_STREAM (seekable));
 325 }
 326
 327 static gboolean
 328 g_file_output_stream_can_seek (GFileOutputStream  *stream)
 329 {
 330   GFileOutputStreamClass *class;
 331   gboolean can_seek;
 332
 333   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 334
 335   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 336
 337   can_seek = FALSE;
 338   if (class->seek)
 339     {
 340       can_seek = TRUE;
 341       if (class->can_seek)
 342         can_seek = class->can_seek (stream);
 343     }
 344
 345   return can_seek;
 346 }
 347
 348 static gboolean
 349 g_file_output_stream_seekable_can_seek (GSeekable *seekable)
 350 {
 351   return g_file_output_stream_can_seek (G_FILE_OUTPUT_STREAM (seekable));
 352 }
 353
 354 static gboolean
 355 g_file_output_stream_seek (GFileOutputStream  *stream,
 356                            goffset             offset,
 357                            GSeekType           type,
 358                            GCancellable       *cancellable,
 359                            GError            **error)
 360 {
 361   GFileOutputStreamClass *class;
 362   GOutputStream *output_stream;
 363   gboolean res;
 364
 365   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 366
 367   output_stream = G_OUTPUT_STREAM (stream);
 368   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 369
 370   if (!class->seek)
 371     {
 372       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 373                            _("Seek not supported on stream"));
 374       return FALSE;
 375     }
 376
 377   if (!g_output_stream_set_pending (output_stream, error))
 378     return FALSE;
 379
 380   if (cancellable)
 381     g_cancellable_push_current (cancellable);
 382
 383   res = class->seek (stream, offset, type, cancellable, error);
 384
 385   if (cancellable)
 386     g_cancellable_pop_current (cancellable);
 387
 388   g_output_stream_clear_pending (output_stream);
 389
 390   return res;
 391 }
 392
 393 static gboolean
 394 g_file_output_stream_seekable_seek (GSeekable  *seekable,
 395                                     goffset     offset,
 396                                     GSeekType   type,
 397                                     GCancellable  *cancellable,
 398                                     GError    **error)
 399 {
 400   return g_file_output_stream_seek (G_FILE_OUTPUT_STREAM (seekable),
 401                                     offset, type, cancellable, error);
 402 }
 403
 404 static gboolean
 405 g_file_output_stream_can_truncate (GFileOutputStream  *stream)
 406 {
 407   GFileOutputStreamClass *class;
 408   gboolean can_truncate;
 409
 410   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 411
 412   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 413
 414   can_truncate = FALSE;
 415   if (class->truncate_fn)
 416     {
 417       can_truncate = TRUE;
 418       if (class->can_truncate)
 419         can_truncate = class->can_truncate (stream);
 420     }
 421
 422   return can_truncate;
 423 }
 424
 425 static gboolean
 426 g_file_output_stream_seekable_can_truncate (GSeekable  *seekable)
 427 {
 428   return g_file_output_stream_can_truncate (G_FILE_OUTPUT_STREAM (seekable));
 429 }
 430
 431 static gboolean
 432 g_file_output_stream_truncate (GFileOutputStream  *stream,
 433                                goffset             size,
 434                                GCancellable       *cancellable,
 435                                GError            **error)
 436 {
 437   GFileOutputStreamClass *class;
 438   GOutputStream *output_stream;
 439   gboolean res;
 440
 441   g_return_val_if_fail (G_IS_FILE_OUTPUT_STREAM (stream), FALSE);
 442
 443   output_stream = G_OUTPUT_STREAM (stream);
 444   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 445
 446   if (!class->truncate_fn)
 447     {
 448       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 449                            _("Truncate not supported on stream"));
 450       return FALSE;
 451     }
 452
 453   if (!g_output_stream_set_pending (output_stream, error))
 454     return FALSE;
 455
 456   if (cancellable)
 457     g_cancellable_push_current (cancellable);
 458
 459   res = class->truncate_fn (stream, size, cancellable, error);
 460
 461   if (cancellable)
 462     g_cancellable_pop_current (cancellable);
 463
 464   g_output_stream_clear_pending (output_stream);
 465
 466   return res;
 467 }
 468
 469 static gboolean
 470 g_file_output_stream_seekable_truncate (GSeekable     *seekable,
 471                                         goffset        size,
 472                                         GCancellable  *cancellable,
 473                                         GError       **error)
 474 {
 475   return g_file_output_stream_truncate (G_FILE_OUTPUT_STREAM (seekable),
 476                                         size, cancellable, error);
 477 }
 478 /********************************************
 479  *   Default implementation of async ops    *
 480  ********************************************/
 481
 482 static void
 483 query_info_async_thread (GTask        *task,
 484                          gpointer      source_object,
 485                          gpointer      task_data,
 486                          GCancellable *cancellable)
 487 {
 488   GFileOutputStream *stream = source_object;
 489   const char *attributes = task_data;
 490   GFileOutputStreamClass *class;
 491   GError *error = NULL;
 492   GFileInfo *info = NULL;
 493
 494   class = G_FILE_OUTPUT_STREAM_GET_CLASS (stream);
 495   if (class->query_info)
 496     info = class->query_info (stream, attributes, cancellable, &error);
 497   else
 498     g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 499                          _("Stream doesn’t support query_info"));
 500
 501   if (info == NULL)
 502     g_task_return_error (task, error);
 503   else
 504     g_task_return_pointer (task, info, g_object_unref);
 505 }
 506
 507 static void
 508 g_file_output_stream_real_query_info_async (GFileOutputStream     *stream,
 509                                                const char           *attributes,
 510                                                int                   io_priority,
 511                                                GCancellable         *cancellable,
 512                                                GAsyncReadyCallback   callback,
 513                                                gpointer              user_data)
 514 {
 515   GTask *task;
 516
 517   task = g_task_new (stream, cancellable, callback, user_data);
 518   g_task_set_source_tag (task, g_file_output_stream_real_query_info_async);
 519   g_task_set_task_data (task, g_strdup (attributes), g_free);
 520   g_task_set_priority (task, io_priority);
 521
 522   g_task_run_in_thread (task, query_info_async_thread);
 523   g_object_unref (task);
 524 }
 525
 526 static GFileInfo *
 527 g_file_output_stream_real_query_info_finish (GFileOutputStream     *stream,
 528                                              GAsyncResult         *res,
 529                                              GError              **error)
 530 {
 531   g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
 532
 533   return g_task_propagate_pointer (G_TASK (res), error);
 534 }