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, 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 <gfileiostream.h>
  27 #include <gseekable.h>
  28 #include "gsimpleasyncresult.h"
  29 #include "gasyncresult.h"
  30 #include "gcancellable.h"
  31 #include "gioerror.h"
  32 #include "gfileoutputstream.h"
  33 #include "glibintl.h"
  34
  35
  36 /**
  37  * SECTION:gfileiostream
  38  * @short_description:  File read and write streaming operations
  39  * @include: gio/gio.h
  40  * @see_also: #GIOStream, #GFileInputStream, #GFileOutputStream, #GSeekable
  41  *
  42  * GFileIOStream provides io streams that both read and write to the same
  43  * file handle.
  44  *
  45  * GFileIOStream implements #GSeekable, which allows the io
  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.
  49  *
  50  * To find the position of a file io stream, use
  51  * g_seekable_tell().
  52  *
  53  * To find out if a file io stream supports seeking, use g_seekable_can_seek().
  54  * To position a file io stream, use g_seekable_seek().
  55  * To find out if a file io stream supports truncating, use
  56  * g_seekable_can_truncate(). To truncate a file io
  57  * stream, use g_seekable_truncate().
  58  *
  59  * The default implementation of all the #GFileIOStream operations
  60  * and the implementation of #GSeekable just call into the same operations
  61  * on the output stream.
  62  * Since: 2.22
  63  **/
  64
  65 static void       g_file_io_stream_seekable_iface_init    (GSeekableIface       *iface);
  66 static goffset    g_file_io_stream_seekable_tell          (GSeekable            *seekable);
  67 static gboolean   g_file_io_stream_seekable_can_seek      (GSeekable            *seekable);
  68 static gboolean   g_file_io_stream_seekable_seek          (GSeekable            *seekable,
  69                                                            goffset               offset,
  70                                                            GSeekType             type,
  71                                                            GCancellable         *cancellable,
  72                                                            GError              **error);
  73 static gboolean   g_file_io_stream_seekable_can_truncate  (GSeekable            *seekable);
  74 static gboolean   g_file_io_stream_seekable_truncate      (GSeekable            *seekable,
  75                                                            goffset               offset,
  76                                                            GCancellable         *cancellable,
  77                                                            GError              **error);
  78 static void       g_file_io_stream_real_query_info_async  (GFileIOStream    *stream,
  79                                                            const char           *attributes,
  80                                                            int                   io_priority,
  81                                                            GCancellable         *cancellable,
  82                                                            GAsyncReadyCallback   callback,
  83                                                            gpointer              user_data);
  84 static GFileInfo *g_file_io_stream_real_query_info_finish (GFileIOStream    *stream,
  85                                                            GAsyncResult         *result,
  86                                                            GError              **error);
  87
  88 G_DEFINE_TYPE_WITH_CODE (GFileIOStream, g_file_io_stream, G_TYPE_IO_STREAM,
  89                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  90                                                 g_file_io_stream_seekable_iface_init));
  91
  92 struct _GFileIOStreamPrivate {
  93   GAsyncReadyCallback outstanding_callback;
  94 };
  95
  96 static void
  97 g_file_io_stream_seekable_iface_init (GSeekableIface *iface)
  98 {
  99   iface->tell = g_file_io_stream_seekable_tell;
 100   iface->can_seek = g_file_io_stream_seekable_can_seek;
 101   iface->seek = g_file_io_stream_seekable_seek;
 102   iface->can_truncate = g_file_io_stream_seekable_can_truncate;
 103   iface->truncate_fn = g_file_io_stream_seekable_truncate;
 104 }
 105
 106 static void
 107 g_file_io_stream_init (GFileIOStream *stream)
 108 {
 109   stream->priv = G_TYPE_INSTANCE_GET_PRIVATE (stream,
 110                                               G_TYPE_FILE_IO_STREAM,
 111                                               GFileIOStreamPrivate);
 112 }
 113
 114 /**
 115  * g_file_io_stream_query_info:
 116  * @stream: a #GFileIOStream.
 117  * @attributes: a file attribute query string.
 118  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 119  * @error: a #GError, %NULL to ignore.
 120  *
 121  * Queries a file io stream for the given @attributes.
 122  * This function blocks while querying the stream. For the asynchronous
 123  * version of this function, see g_file_io_stream_query_info_async().
 124  * While the stream is blocked, the stream will set the pending flag
 125  * internally, and any other operations on the stream will fail with
 126  * %G_IO_ERROR_PENDING.
 127  *
 128  * Can fail if the stream was already closed (with @error being set to
 129  * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
 130  * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
 131  * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). I
 132  * all cases of failure, %NULL will be returned.
 133  *
 134  * If @cancellable is not %NULL, then the operation can be cancelled by
 135  * triggering the cancellable object from another thread. If the operation
 136  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
 137  * be returned.
 138  *
 139  * Returns: (transfer full): a #GFileInfo for the @stream, or %NULL on error.
 140  *
 141  * Since: 2.22
 142  **/
 143 GFileInfo *
 144 g_file_io_stream_query_info (GFileIOStream      *stream,
 145                              const char             *attributes,
 146                              GCancellable           *cancellable,
 147                              GError                **error)
 148 {
 149   GFileIOStreamClass *class;
 150   GIOStream *io_stream;
 151   GFileInfo *info;
 152
 153   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 154
 155   io_stream = G_IO_STREAM (stream);
 156
 157   if (!g_io_stream_set_pending (io_stream, error))
 158     return NULL;
 159
 160   info = NULL;
 161
 162   if (cancellable)
 163     g_cancellable_push_current (cancellable);
 164
 165   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 166   if (class->query_info)
 167     info = class->query_info (stream, attributes, cancellable, error);
 168   else
 169     g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 170                          _("Stream doesn't support query_info"));
 171
 172   if (cancellable)
 173     g_cancellable_pop_current (cancellable);
 174
 175   g_io_stream_clear_pending (io_stream);
 176
 177   return info;
 178 }
 179
 180 static void
 181 async_ready_callback_wrapper (GObject *source_object,
 182                               GAsyncResult *res,
 183                               gpointer      user_data)
 184 {
 185   GFileIOStream *stream = G_FILE_IO_STREAM (source_object);
 186
 187   g_io_stream_clear_pending (G_IO_STREAM (stream));
 188   if (stream->priv->outstanding_callback)
 189     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 190   g_object_unref (stream);
 191 }
 192
 193 /**
 194  * g_file_io_stream_query_info_async:
 195  * @stream: a #GFileIOStream.
 196  * @attributes: a file attribute query string.
 197  * @io_priority: the <link linkend="gio-GIOScheduler">I/O priority</link>
 198  *     of the request.
 199  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 200  * @callback: (scope async): callback to call when the request is satisfied
 201  * @user_data: (closure): the data to pass to callback function
 202  *
 203  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 204  * @callback will be called with a #GAsyncResult which can be used to
 205  * finish the operation with g_file_io_stream_query_info_finish().
 206  *
 207  * For the synchronous version of this function, see
 208  * g_file_io_stream_query_info().
 209  *
 210  * Since: 2.22
 211  **/
 212 void
 213 g_file_io_stream_query_info_async (GFileIOStream     *stream,
 214                                           const char           *attributes,
 215                                           int                   io_priority,
 216                                           GCancellable         *cancellable,
 217                                           GAsyncReadyCallback   callback,
 218                                           gpointer              user_data)
 219 {
 220   GFileIOStreamClass *klass;
 221   GIOStream *io_stream;
 222   GError *error = NULL;
 223
 224   g_return_if_fail (G_IS_FILE_IO_STREAM (stream));
 225
 226   io_stream = G_IO_STREAM (stream);
 227
 228   if (!g_io_stream_set_pending (io_stream, &error))
 229     {
 230       g_simple_async_report_take_gerror_in_idle (G_OBJECT (stream),
 231                                             callback,
 232                                             user_data,
 233                                             error);
 234       return;
 235     }
 236
 237   klass = G_FILE_IO_STREAM_GET_CLASS (stream);
 238
 239   stream->priv->outstanding_callback = callback;
 240   g_object_ref (stream);
 241   klass->query_info_async (stream, attributes, io_priority, cancellable,
 242                               async_ready_callback_wrapper, user_data);
 243 }
 244
 245 /**
 246  * g_file_io_stream_query_info_finish:
 247  * @stream: a #GFileIOStream.
 248  * @result: a #GAsyncResult.
 249  * @error: a #GError, %NULL to ignore.
 250  *
 251  * Finalizes the asynchronous query started
 252  * by g_file_io_stream_query_info_async().
 253  *
 254  * Returns: (transfer full): A #GFileInfo for the finished query.
 255  *
 256  * Since: 2.22
 257  **/
 258 GFileInfo *
 259 g_file_io_stream_query_info_finish (GFileIOStream     *stream,
 260                                     GAsyncResult         *result,
 261                                     GError              **error)
 262 {
 263   GFileIOStreamClass *class;
 264
 265   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 266   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 267
 268   if (g_async_result_legacy_propagate_error (result, error))
 269     return NULL;
 270
 271   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 272   return class->query_info_finish (stream, result, error);
 273 }
 274
 275 /**
 276  * g_file_io_stream_get_etag:
 277  * @stream: a #GFileIOStream.
 278  *
 279  * Gets the entity tag for the file when it has been written.
 280  * This must be called after the stream has been written
 281  * and closed, as the etag can change while writing.
 282  *
 283  * Returns: the entity tag for the stream.
 284  *
 285  * Since: 2.22
 286  **/
 287 char *
 288 g_file_io_stream_get_etag (GFileIOStream  *stream)
 289 {
 290   GFileIOStreamClass *class;
 291   GIOStream *io_stream;
 292   char *etag;
 293
 294   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 295
 296   io_stream = G_IO_STREAM (stream);
 297
 298   if (!g_io_stream_is_closed (io_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_IO_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_io_stream_tell (GFileIOStream  *stream)
 315 {
 316   GFileIOStreamClass *class;
 317   goffset offset;
 318
 319   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), 0);
 320
 321   class = G_FILE_IO_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_io_stream_seekable_tell (GSeekable *seekable)
 332 {
 333   return g_file_io_stream_tell (G_FILE_IO_STREAM (seekable));
 334 }
 335
 336 static gboolean
 337 g_file_io_stream_can_seek (GFileIOStream  *stream)
 338 {
 339   GFileIOStreamClass *class;
 340   gboolean can_seek;
 341
 342   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 343
 344   class = G_FILE_IO_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_io_stream_seekable_can_seek (GSeekable *seekable)
 359 {
 360   return g_file_io_stream_can_seek (G_FILE_IO_STREAM (seekable));
 361 }
 362
 363 static gboolean
 364 g_file_io_stream_seek (GFileIOStream  *stream,
 365                        goffset             offset,
 366                        GSeekType           type,
 367                        GCancellable       *cancellable,
 368                        GError            **error)
 369 {
 370   GFileIOStreamClass *class;
 371   GIOStream *io_stream;
 372   gboolean res;
 373
 374   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 375
 376   io_stream = G_IO_STREAM (stream);
 377   class = G_FILE_IO_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_io_stream_set_pending (io_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_io_stream_clear_pending (io_stream);
 398
 399   return res;
 400 }
 401
 402 static gboolean
 403 g_file_io_stream_seekable_seek (GSeekable  *seekable,
 404                                     goffset     offset,
 405                                     GSeekType   type,
 406                                     GCancellable  *cancellable,
 407                                     GError    **error)
 408 {
 409   return g_file_io_stream_seek (G_FILE_IO_STREAM (seekable),
 410                                 offset, type, cancellable, error);
 411 }
 412
 413 static gboolean
 414 g_file_io_stream_can_truncate (GFileIOStream  *stream)
 415 {
 416   GFileIOStreamClass *class;
 417   gboolean can_truncate;
 418
 419   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 420
 421   class = G_FILE_IO_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_io_stream_seekable_can_truncate (GSeekable  *seekable)
 436 {
 437   return g_file_io_stream_can_truncate (G_FILE_IO_STREAM (seekable));
 438 }
 439
 440 static gboolean
 441 g_file_io_stream_truncate (GFileIOStream  *stream,
 442                            goffset             size,
 443                            GCancellable       *cancellable,
 444                            GError            **error)
 445 {
 446   GFileIOStreamClass *class;
 447   GIOStream *io_stream;
 448   gboolean res;
 449
 450   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 451
 452   io_stream = G_IO_STREAM (stream);
 453   class = G_FILE_IO_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_io_stream_set_pending (io_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_io_stream_clear_pending (io_stream);
 474
 475   return res;
 476 }
 477
 478 static gboolean
 479 g_file_io_stream_seekable_truncate (GSeekable     *seekable,
 480                                     goffset        size,
 481                                     GCancellable  *cancellable,
 482                                     GError       **error)
 483 {
 484   return g_file_io_stream_truncate (G_FILE_IO_STREAM (seekable),
 485                                         size, cancellable, error);
 486 }
 487 /*****************************************************
 488  *   Default implementations based on output stream  *
 489  *****************************************************/
 490
 491 static goffset
 492 g_file_io_stream_real_tell (GFileIOStream    *stream)
 493 {
 494   GOutputStream *out;
 495   GSeekable *seekable;
 496
 497   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 498   seekable = G_SEEKABLE (out);
 499
 500   return g_seekable_tell (seekable);
 501 }
 502
 503 static gboolean
 504 g_file_io_stream_real_can_seek (GFileIOStream    *stream)
 505 {
 506   GOutputStream *out;
 507   GSeekable *seekable;
 508
 509   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 510   seekable = G_SEEKABLE (out);
 511
 512   return g_seekable_can_seek (seekable);
 513 }
 514
 515 static gboolean
 516 g_file_io_stream_real_seek (GFileIOStream    *stream,
 517                             goffset           offset,
 518                             GSeekType         type,
 519                             GCancellable     *cancellable,
 520                             GError          **error)
 521 {
 522   GOutputStream *out;
 523   GSeekable *seekable;
 524
 525   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 526   seekable = G_SEEKABLE (out);
 527
 528   return g_seekable_seek (seekable, offset, type, cancellable, error);
 529 }
 530
 531 static  gboolean
 532 g_file_io_stream_real_can_truncate (GFileIOStream    *stream)
 533 {
 534   GOutputStream *out;
 535   GSeekable *seekable;
 536
 537   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 538   seekable = G_SEEKABLE (out);
 539
 540   return g_seekable_can_truncate (seekable);
 541 }
 542
 543 static gboolean
 544 g_file_io_stream_real_truncate_fn (GFileIOStream    *stream,
 545                                    goffset               size,
 546                                    GCancellable         *cancellable,
 547                                    GError              **error)
 548 {
 549   GOutputStream *out;
 550   GSeekable *seekable;
 551
 552   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 553   seekable = G_SEEKABLE (out);
 554
 555   return g_seekable_truncate (seekable, size, cancellable, error);
 556 }
 557
 558 static char *
 559 g_file_io_stream_real_get_etag (GFileIOStream    *stream)
 560 {
 561   GOutputStream *out;
 562   GFileOutputStream *file_out;
 563
 564   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 565   file_out = G_FILE_OUTPUT_STREAM (out);
 566
 567   return g_file_output_stream_get_etag (file_out);
 568 }
 569
 570 static GFileInfo *
 571 g_file_io_stream_real_query_info (GFileIOStream    *stream,
 572                                   const char           *attributes,
 573                                   GCancellable         *cancellable,
 574                                   GError              **error)
 575 {
 576   GOutputStream *out;
 577   GFileOutputStream *file_out;
 578
 579   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 580   file_out = G_FILE_OUTPUT_STREAM (out);
 581
 582   return g_file_output_stream_query_info (file_out,
 583                                           attributes, cancellable, error);
 584 }
 585
 586 typedef struct {
 587   GObject *object;
 588   GAsyncReadyCallback callback;
 589   gpointer user_data;
 590 } AsyncOpWrapper;
 591
 592 static AsyncOpWrapper *
 593 async_op_wrapper_new (gpointer object,
 594                       GAsyncReadyCallback callback,
 595                       gpointer user_data)
 596 {
 597   AsyncOpWrapper *data;
 598
 599   data = g_new0 (AsyncOpWrapper, 1);
 600   data->object = g_object_ref (object);
 601   data->callback = callback;
 602   data->user_data = user_data;
 603
 604   return data;
 605 }
 606
 607 static void
 608 async_op_wrapper_callback (GObject *source_object,
 609                            GAsyncResult *res,
 610                            gpointer user_data)
 611 {
 612   AsyncOpWrapper *data  = user_data;
 613   data->callback (data->object, res, data->user_data);
 614   g_object_unref (data->object);
 615   g_free (data);
 616 }
 617
 618 static void
 619 g_file_io_stream_real_query_info_async (GFileIOStream     *stream,
 620                                         const char           *attributes,
 621                                         int                   io_priority,
 622                                         GCancellable         *cancellable,
 623                                         GAsyncReadyCallback   callback,
 624                                         gpointer              user_data)
 625 {
 626   GOutputStream *out;
 627   GFileOutputStream *file_out;
 628   AsyncOpWrapper *data;
 629
 630   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 631   file_out = G_FILE_OUTPUT_STREAM (out);
 632
 633   data = async_op_wrapper_new (stream, callback, user_data);
 634   g_file_output_stream_query_info_async (file_out,
 635                                          attributes, io_priority,
 636                                          cancellable, async_op_wrapper_callback, data);
 637 }
 638
 639 static GFileInfo *
 640 g_file_io_stream_real_query_info_finish (GFileIOStream     *stream,
 641                                          GAsyncResult      *res,
 642                                          GError           **error)
 643 {
 644   GOutputStream *out;
 645   GFileOutputStream *file_out;
 646
 647   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 648   file_out = G_FILE_OUTPUT_STREAM (out);
 649
 650   return g_file_output_stream_query_info_finish (file_out, res, error);
 651 }
 652
 653 static void
 654 g_file_io_stream_class_init (GFileIOStreamClass *klass)
 655 {
 656   g_type_class_add_private (klass, sizeof (GFileIOStreamPrivate));
 657
 658   klass->tell = g_file_io_stream_real_tell;
 659   klass->can_seek = g_file_io_stream_real_can_seek;
 660   klass->seek = g_file_io_stream_real_seek;
 661   klass->can_truncate = g_file_io_stream_real_can_truncate;
 662   klass->truncate_fn = g_file_io_stream_real_truncate_fn;
 663   klass->query_info = g_file_io_stream_real_query_info;
 664   klass->query_info_async = g_file_io_stream_real_query_info_async;
 665   klass->query_info_finish = g_file_io_stream_real_query_info_finish;
 666   klass->get_etag = g_file_io_stream_real_get_etag;
 667 }