gio/gfileiostream.c

   1 /* GIO - GLib Input, IO 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, see <http://www.gnu.org/licenses/>.
  17  *
  18  * Author: Alexander Larsson <alexl@redhat.com>
  19  */
  20
  21 #include "config.h"
  22
  23 #include <glib.h>
  24 #include <gfileiostream.h>
  25 #include <gseekable.h>
  26 #include "gasyncresult.h"
  27 #include "gtask.h"
  28 #include "gcancellable.h"
  29 #include "gioerror.h"
  30 #include "gfileoutputstream.h"
  31 #include "glibintl.h"
  32
  33
  34 /**
  35  * SECTION:gfileiostream
  36  * @short_description:  File read and write streaming operations
  37  * @include: gio/gio.h
  38  * @see_also: #GIOStream, #GFileInputStream, #GFileOutputStream, #GSeekable
  39  *
  40  * GFileIOStream provides io streams that both read and write to the same
  41  * file handle.
  42  *
  43  * GFileIOStream implements #GSeekable, which allows the io
  44  * stream to jump to arbitrary positions in the file and to truncate
  45  * the file, provided the filesystem of the file supports these
  46  * operations.
  47  *
  48  * To find the position of a file io stream, use
  49  * g_seekable_tell().
  50  *
  51  * To find out if a file io stream supports seeking, use g_seekable_can_seek().
  52  * To position a file io stream, use g_seekable_seek().
  53  * To find out if a file io stream supports truncating, use
  54  * g_seekable_can_truncate(). To truncate a file io
  55  * stream, use g_seekable_truncate().
  56  *
  57  * The default implementation of all the #GFileIOStream operations
  58  * and the implementation of #GSeekable just call into the same operations
  59  * on the output stream.
  60  * Since: 2.22
  61  **/
  62
  63 static void       g_file_io_stream_seekable_iface_init    (GSeekableIface       *iface);
  64 static goffset    g_file_io_stream_seekable_tell          (GSeekable            *seekable);
  65 static gboolean   g_file_io_stream_seekable_can_seek      (GSeekable            *seekable);
  66 static gboolean   g_file_io_stream_seekable_seek          (GSeekable            *seekable,
  67                                                            goffset               offset,
  68                                                            GSeekType             type,
  69                                                            GCancellable         *cancellable,
  70                                                            GError              **error);
  71 static gboolean   g_file_io_stream_seekable_can_truncate  (GSeekable            *seekable);
  72 static gboolean   g_file_io_stream_seekable_truncate      (GSeekable            *seekable,
  73                                                            goffset               offset,
  74                                                            GCancellable         *cancellable,
  75                                                            GError              **error);
  76 static void       g_file_io_stream_real_query_info_async  (GFileIOStream    *stream,
  77                                                            const char           *attributes,
  78                                                            int                   io_priority,
  79                                                            GCancellable         *cancellable,
  80                                                            GAsyncReadyCallback   callback,
  81                                                            gpointer              user_data);
  82 static GFileInfo *g_file_io_stream_real_query_info_finish (GFileIOStream    *stream,
  83                                                            GAsyncResult         *result,
  84                                                            GError              **error);
  85
  86 struct _GFileIOStreamPrivate {
  87   GAsyncReadyCallback outstanding_callback;
  88 };
  89
  90 G_DEFINE_TYPE_WITH_CODE (GFileIOStream, g_file_io_stream, G_TYPE_IO_STREAM,
  91                          G_ADD_PRIVATE (GFileIOStream)
  92                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  93                                                 g_file_io_stream_seekable_iface_init))
  94
  95 static void
  96 g_file_io_stream_seekable_iface_init (GSeekableIface *iface)
  97 {
  98   iface->tell = g_file_io_stream_seekable_tell;
  99   iface->can_seek = g_file_io_stream_seekable_can_seek;
 100   iface->seek = g_file_io_stream_seekable_seek;
 101   iface->can_truncate = g_file_io_stream_seekable_can_truncate;
 102   iface->truncate_fn = g_file_io_stream_seekable_truncate;
 103 }
 104
 105 static void
 106 g_file_io_stream_init (GFileIOStream *stream)
 107 {
 108   stream->priv = g_file_io_stream_get_instance_private (stream);
 109 }
 110
 111 /**
 112  * g_file_io_stream_query_info:
 113  * @stream: a #GFileIOStream.
 114  * @attributes: a file attribute query string.
 115  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 116  * @error: a #GError, %NULL to ignore.
 117  *
 118  * Queries a file io stream for the given @attributes.
 119  * This function blocks while querying the stream. For the asynchronous
 120  * version of this function, see g_file_io_stream_query_info_async().
 121  * While the stream is blocked, the stream will set the pending flag
 122  * internally, and any other operations on the stream will fail with
 123  * %G_IO_ERROR_PENDING.
 124  *
 125  * Can fail if the stream was already closed (with @error being set to
 126  * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
 127  * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
 128  * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). I
 129  * all cases of failure, %NULL will be returned.
 130  *
 131  * If @cancellable is not %NULL, then the operation can be cancelled by
 132  * triggering the cancellable object from another thread. If the operation
 133  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
 134  * be returned.
 135  *
 136  * Returns: (transfer full): a #GFileInfo for the @stream, or %NULL on error.
 137  *
 138  * Since: 2.22
 139  **/
 140 GFileInfo *
 141 g_file_io_stream_query_info (GFileIOStream      *stream,
 142                              const char             *attributes,
 143                              GCancellable           *cancellable,
 144                              GError                **error)
 145 {
 146   GFileIOStreamClass *class;
 147   GIOStream *io_stream;
 148   GFileInfo *info;
 149
 150   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 151
 152   io_stream = G_IO_STREAM (stream);
 153
 154   if (!g_io_stream_set_pending (io_stream, error))
 155     return NULL;
 156
 157   info = NULL;
 158
 159   if (cancellable)
 160     g_cancellable_push_current (cancellable);
 161
 162   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 163   if (class->query_info)
 164     info = class->query_info (stream, attributes, cancellable, error);
 165   else
 166     g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 167                          _("Stream doesn't support query_info"));
 168
 169   if (cancellable)
 170     g_cancellable_pop_current (cancellable);
 171
 172   g_io_stream_clear_pending (io_stream);
 173
 174   return info;
 175 }
 176
 177 static void
 178 async_ready_callback_wrapper (GObject *source_object,
 179                               GAsyncResult *res,
 180                               gpointer      user_data)
 181 {
 182   GFileIOStream *stream = G_FILE_IO_STREAM (source_object);
 183
 184   g_io_stream_clear_pending (G_IO_STREAM (stream));
 185   if (stream->priv->outstanding_callback)
 186     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 187   g_object_unref (stream);
 188 }
 189
 190 /**
 191  * g_file_io_stream_query_info_async:
 192  * @stream: a #GFileIOStream.
 193  * @attributes: a file attribute query string.
 194  * @io_priority: the [I/O priority][gio-GIOScheduler] of the request
 195  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 196  * @callback: (scope async): callback to call when the request is satisfied
 197  * @user_data: (closure): the data to pass to callback function
 198  *
 199  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 200  * @callback will be called with a #GAsyncResult which can be used to
 201  * finish the operation with g_file_io_stream_query_info_finish().
 202  *
 203  * For the synchronous version of this function, see
 204  * g_file_io_stream_query_info().
 205  *
 206  * Since: 2.22
 207  **/
 208 void
 209 g_file_io_stream_query_info_async (GFileIOStream     *stream,
 210                                           const char           *attributes,
 211                                           int                   io_priority,
 212                                           GCancellable         *cancellable,
 213                                           GAsyncReadyCallback   callback,
 214                                           gpointer              user_data)
 215 {
 216   GFileIOStreamClass *klass;
 217   GIOStream *io_stream;
 218   GError *error = NULL;
 219
 220   g_return_if_fail (G_IS_FILE_IO_STREAM (stream));
 221
 222   io_stream = G_IO_STREAM (stream);
 223
 224   if (!g_io_stream_set_pending (io_stream, &error))
 225     {
 226       g_task_report_error (stream, callback, user_data,
 227                            g_file_io_stream_query_info_async,
 228                            error);
 229       return;
 230     }
 231
 232   klass = G_FILE_IO_STREAM_GET_CLASS (stream);
 233
 234   stream->priv->outstanding_callback = callback;
 235   g_object_ref (stream);
 236   klass->query_info_async (stream, attributes, io_priority, cancellable,
 237                            async_ready_callback_wrapper, user_data);
 238 }
 239
 240 /**
 241  * g_file_io_stream_query_info_finish:
 242  * @stream: a #GFileIOStream.
 243  * @result: a #GAsyncResult.
 244  * @error: a #GError, %NULL to ignore.
 245  *
 246  * Finalizes the asynchronous query started
 247  * by g_file_io_stream_query_info_async().
 248  *
 249  * Returns: (transfer full): A #GFileInfo for the finished query.
 250  *
 251  * Since: 2.22
 252  **/
 253 GFileInfo *
 254 g_file_io_stream_query_info_finish (GFileIOStream     *stream,
 255                                     GAsyncResult         *result,
 256                                     GError              **error)
 257 {
 258   GFileIOStreamClass *class;
 259
 260   g_return_val_if_fail (G_IS_FILE_IO_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_io_stream_query_info_async))
 266     return g_task_propagate_pointer (G_TASK (result), error);
 267
 268   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 269   return class->query_info_finish (stream, result, error);
 270 }
 271
 272 /**
 273  * g_file_io_stream_get_etag:
 274  * @stream: a #GFileIOStream.
 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  * Since: 2.22
 283  **/
 284 char *
 285 g_file_io_stream_get_etag (GFileIOStream  *stream)
 286 {
 287   GFileIOStreamClass *class;
 288   GIOStream *io_stream;
 289   char *etag;
 290
 291   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 292
 293   io_stream = G_IO_STREAM (stream);
 294
 295   if (!g_io_stream_is_closed (io_stream))
 296     {
 297       g_warning ("stream is not closed yet, can't get etag");
 298       return NULL;
 299     }
 300
 301   etag = NULL;
 302
 303   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 304   if (class->get_etag)
 305     etag = class->get_etag (stream);
 306
 307   return etag;
 308 }
 309
 310 static goffset
 311 g_file_io_stream_tell (GFileIOStream  *stream)
 312 {
 313   GFileIOStreamClass *class;
 314   goffset offset;
 315
 316   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), 0);
 317
 318   class = G_FILE_IO_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_io_stream_seekable_tell (GSeekable *seekable)
 329 {
 330   return g_file_io_stream_tell (G_FILE_IO_STREAM (seekable));
 331 }
 332
 333 static gboolean
 334 g_file_io_stream_can_seek (GFileIOStream  *stream)
 335 {
 336   GFileIOStreamClass *class;
 337   gboolean can_seek;
 338
 339   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 340
 341   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 342
 343   can_seek = FALSE;
 344   if (class->seek)
 345     {
 346       can_seek = TRUE;
 347       if (class->can_seek)
 348         can_seek = class->can_seek (stream);
 349     }
 350
 351   return can_seek;
 352 }
 353
 354 static gboolean
 355 g_file_io_stream_seekable_can_seek (GSeekable *seekable)
 356 {
 357   return g_file_io_stream_can_seek (G_FILE_IO_STREAM (seekable));
 358 }
 359
 360 static gboolean
 361 g_file_io_stream_seek (GFileIOStream  *stream,
 362                        goffset             offset,
 363                        GSeekType           type,
 364                        GCancellable       *cancellable,
 365                        GError            **error)
 366 {
 367   GFileIOStreamClass *class;
 368   GIOStream *io_stream;
 369   gboolean res;
 370
 371   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 372
 373   io_stream = G_IO_STREAM (stream);
 374   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 375
 376   if (!class->seek)
 377     {
 378       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 379                            _("Seek not supported on stream"));
 380       return FALSE;
 381     }
 382
 383   if (!g_io_stream_set_pending (io_stream, error))
 384     return FALSE;
 385
 386   if (cancellable)
 387     g_cancellable_push_current (cancellable);
 388
 389   res = class->seek (stream, offset, type, cancellable, error);
 390
 391   if (cancellable)
 392     g_cancellable_pop_current (cancellable);
 393
 394   g_io_stream_clear_pending (io_stream);
 395
 396   return res;
 397 }
 398
 399 static gboolean
 400 g_file_io_stream_seekable_seek (GSeekable  *seekable,
 401                                     goffset     offset,
 402                                     GSeekType   type,
 403                                     GCancellable  *cancellable,
 404                                     GError    **error)
 405 {
 406   return g_file_io_stream_seek (G_FILE_IO_STREAM (seekable),
 407                                 offset, type, cancellable, error);
 408 }
 409
 410 static gboolean
 411 g_file_io_stream_can_truncate (GFileIOStream  *stream)
 412 {
 413   GFileIOStreamClass *class;
 414   gboolean can_truncate;
 415
 416   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 417
 418   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 419
 420   can_truncate = FALSE;
 421   if (class->truncate_fn)
 422     {
 423       can_truncate = TRUE;
 424       if (class->can_truncate)
 425         can_truncate = class->can_truncate (stream);
 426     }
 427
 428   return can_truncate;
 429 }
 430
 431 static gboolean
 432 g_file_io_stream_seekable_can_truncate (GSeekable  *seekable)
 433 {
 434   return g_file_io_stream_can_truncate (G_FILE_IO_STREAM (seekable));
 435 }
 436
 437 static gboolean
 438 g_file_io_stream_truncate (GFileIOStream  *stream,
 439                            goffset             size,
 440                            GCancellable       *cancellable,
 441                            GError            **error)
 442 {
 443   GFileIOStreamClass *class;
 444   GIOStream *io_stream;
 445   gboolean res;
 446
 447   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 448
 449   io_stream = G_IO_STREAM (stream);
 450   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 451
 452   if (!class->truncate_fn)
 453     {
 454       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 455                            _("Truncate not supported on stream"));
 456       return FALSE;
 457     }
 458
 459   if (!g_io_stream_set_pending (io_stream, error))
 460     return FALSE;
 461
 462   if (cancellable)
 463     g_cancellable_push_current (cancellable);
 464
 465   res = class->truncate_fn (stream, size, cancellable, error);
 466
 467   if (cancellable)
 468     g_cancellable_pop_current (cancellable);
 469
 470   g_io_stream_clear_pending (io_stream);
 471
 472   return res;
 473 }
 474
 475 static gboolean
 476 g_file_io_stream_seekable_truncate (GSeekable     *seekable,
 477                                     goffset        size,
 478                                     GCancellable  *cancellable,
 479                                     GError       **error)
 480 {
 481   return g_file_io_stream_truncate (G_FILE_IO_STREAM (seekable),
 482                                         size, cancellable, error);
 483 }
 484 /*****************************************************
 485  *   Default implementations based on output stream  *
 486  *****************************************************/
 487
 488 static goffset
 489 g_file_io_stream_real_tell (GFileIOStream    *stream)
 490 {
 491   GOutputStream *out;
 492   GSeekable *seekable;
 493
 494   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 495   seekable = G_SEEKABLE (out);
 496
 497   return g_seekable_tell (seekable);
 498 }
 499
 500 static gboolean
 501 g_file_io_stream_real_can_seek (GFileIOStream    *stream)
 502 {
 503   GOutputStream *out;
 504   GSeekable *seekable;
 505
 506   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 507   seekable = G_SEEKABLE (out);
 508
 509   return g_seekable_can_seek (seekable);
 510 }
 511
 512 static gboolean
 513 g_file_io_stream_real_seek (GFileIOStream    *stream,
 514                             goffset           offset,
 515                             GSeekType         type,
 516                             GCancellable     *cancellable,
 517                             GError          **error)
 518 {
 519   GOutputStream *out;
 520   GSeekable *seekable;
 521
 522   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 523   seekable = G_SEEKABLE (out);
 524
 525   return g_seekable_seek (seekable, offset, type, cancellable, error);
 526 }
 527
 528 static  gboolean
 529 g_file_io_stream_real_can_truncate (GFileIOStream    *stream)
 530 {
 531   GOutputStream *out;
 532   GSeekable *seekable;
 533
 534   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 535   seekable = G_SEEKABLE (out);
 536
 537   return g_seekable_can_truncate (seekable);
 538 }
 539
 540 static gboolean
 541 g_file_io_stream_real_truncate_fn (GFileIOStream    *stream,
 542                                    goffset               size,
 543                                    GCancellable         *cancellable,
 544                                    GError              **error)
 545 {
 546   GOutputStream *out;
 547   GSeekable *seekable;
 548
 549   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 550   seekable = G_SEEKABLE (out);
 551
 552   return g_seekable_truncate (seekable, size, cancellable, error);
 553 }
 554
 555 static char *
 556 g_file_io_stream_real_get_etag (GFileIOStream    *stream)
 557 {
 558   GOutputStream *out;
 559   GFileOutputStream *file_out;
 560
 561   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 562   file_out = G_FILE_OUTPUT_STREAM (out);
 563
 564   return g_file_output_stream_get_etag (file_out);
 565 }
 566
 567 static GFileInfo *
 568 g_file_io_stream_real_query_info (GFileIOStream    *stream,
 569                                   const char           *attributes,
 570                                   GCancellable         *cancellable,
 571                                   GError              **error)
 572 {
 573   GOutputStream *out;
 574   GFileOutputStream *file_out;
 575
 576   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 577   file_out = G_FILE_OUTPUT_STREAM (out);
 578
 579   return g_file_output_stream_query_info (file_out,
 580                                           attributes, cancellable, error);
 581 }
 582
 583 typedef struct {
 584   GObject *object;
 585   GAsyncReadyCallback callback;
 586   gpointer user_data;
 587 } AsyncOpWrapper;
 588
 589 static AsyncOpWrapper *
 590 async_op_wrapper_new (gpointer object,
 591                       GAsyncReadyCallback callback,
 592                       gpointer user_data)
 593 {
 594   AsyncOpWrapper *data;
 595
 596   data = g_new0 (AsyncOpWrapper, 1);
 597   data->object = g_object_ref (object);
 598   data->callback = callback;
 599   data->user_data = user_data;
 600
 601   return data;
 602 }
 603
 604 static void
 605 async_op_wrapper_callback (GObject *source_object,
 606                            GAsyncResult *res,
 607                            gpointer user_data)
 608 {
 609   AsyncOpWrapper *data  = user_data;
 610   data->callback (data->object, res, data->user_data);
 611   g_object_unref (data->object);
 612   g_free (data);
 613 }
 614
 615 static void
 616 g_file_io_stream_real_query_info_async (GFileIOStream     *stream,
 617                                         const char           *attributes,
 618                                         int                   io_priority,
 619                                         GCancellable         *cancellable,
 620                                         GAsyncReadyCallback   callback,
 621                                         gpointer              user_data)
 622 {
 623   GOutputStream *out;
 624   GFileOutputStream *file_out;
 625   AsyncOpWrapper *data;
 626
 627   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 628   file_out = G_FILE_OUTPUT_STREAM (out);
 629
 630   data = async_op_wrapper_new (stream, callback, user_data);
 631   g_file_output_stream_query_info_async (file_out,
 632                                          attributes, io_priority,
 633                                          cancellable, async_op_wrapper_callback, data);
 634 }
 635
 636 static GFileInfo *
 637 g_file_io_stream_real_query_info_finish (GFileIOStream     *stream,
 638                                          GAsyncResult      *res,
 639                                          GError           **error)
 640 {
 641   GOutputStream *out;
 642   GFileOutputStream *file_out;
 643
 644   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 645   file_out = G_FILE_OUTPUT_STREAM (out);
 646
 647   return g_file_output_stream_query_info_finish (file_out, res, error);
 648 }
 649
 650 static void
 651 g_file_io_stream_class_init (GFileIOStreamClass *klass)
 652 {
 653   klass->tell = g_file_io_stream_real_tell;
 654   klass->can_seek = g_file_io_stream_real_can_seek;
 655   klass->seek = g_file_io_stream_real_seek;
 656   klass->can_truncate = g_file_io_stream_real_can_truncate;
 657   klass->truncate_fn = g_file_io_stream_real_truncate_fn;
 658   klass->query_info = g_file_io_stream_real_query_info;
 659   klass->query_info_async = g_file_io_stream_real_query_info_async;
 660   klass->query_info_finish = g_file_io_stream_real_query_info_finish;
 661   klass->get_etag = g_file_io_stream_real_get_etag;
 662 }