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 <link linkend="gio-GIOScheduler">I/O priority</link>
 195  *     of the request.
 196  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 197  * @callback: (scope async): callback to call when the request is satisfied
 198  * @user_data: (closure): the data to pass to callback function
 199  *
 200  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 201  * @callback will be called with a #GAsyncResult which can be used to
 202  * finish the operation with g_file_io_stream_query_info_finish().
 203  *
 204  * For the synchronous version of this function, see
 205  * g_file_io_stream_query_info().
 206  *
 207  * Since: 2.22
 208  **/
 209 void
 210 g_file_io_stream_query_info_async (GFileIOStream     *stream,
 211                                           const char           *attributes,
 212                                           int                   io_priority,
 213                                           GCancellable         *cancellable,
 214                                           GAsyncReadyCallback   callback,
 215                                           gpointer              user_data)
 216 {
 217   GFileIOStreamClass *klass;
 218   GIOStream *io_stream;
 219   GError *error = NULL;
 220
 221   g_return_if_fail (G_IS_FILE_IO_STREAM (stream));
 222
 223   io_stream = G_IO_STREAM (stream);
 224
 225   if (!g_io_stream_set_pending (io_stream, &error))
 226     {
 227       g_task_report_error (stream, callback, user_data,
 228                            g_file_io_stream_query_info_async,
 229                            error);
 230       return;
 231     }
 232
 233   klass = G_FILE_IO_STREAM_GET_CLASS (stream);
 234
 235   stream->priv->outstanding_callback = callback;
 236   g_object_ref (stream);
 237   klass->query_info_async (stream, attributes, io_priority, cancellable,
 238                            async_ready_callback_wrapper, user_data);
 239 }
 240
 241 /**
 242  * g_file_io_stream_query_info_finish:
 243  * @stream: a #GFileIOStream.
 244  * @result: a #GAsyncResult.
 245  * @error: a #GError, %NULL to ignore.
 246  *
 247  * Finalizes the asynchronous query started
 248  * by g_file_io_stream_query_info_async().
 249  *
 250  * Returns: (transfer full): A #GFileInfo for the finished query.
 251  *
 252  * Since: 2.22
 253  **/
 254 GFileInfo *
 255 g_file_io_stream_query_info_finish (GFileIOStream     *stream,
 256                                     GAsyncResult         *result,
 257                                     GError              **error)
 258 {
 259   GFileIOStreamClass *class;
 260
 261   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 262   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 263
 264   if (g_async_result_legacy_propagate_error (result, error))
 265     return NULL;
 266   else if (g_async_result_is_tagged (result, g_file_io_stream_query_info_async))
 267     return g_task_propagate_pointer (G_TASK (result), error);
 268
 269   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 270   return class->query_info_finish (stream, result, error);
 271 }
 272
 273 /**
 274  * g_file_io_stream_get_etag:
 275  * @stream: a #GFileIOStream.
 276  *
 277  * Gets the entity tag for the file when it has been written.
 278  * This must be called after the stream has been written
 279  * and closed, as the etag can change while writing.
 280  *
 281  * Returns: the entity tag for the stream.
 282  *
 283  * Since: 2.22
 284  **/
 285 char *
 286 g_file_io_stream_get_etag (GFileIOStream  *stream)
 287 {
 288   GFileIOStreamClass *class;
 289   GIOStream *io_stream;
 290   char *etag;
 291
 292   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 293
 294   io_stream = G_IO_STREAM (stream);
 295
 296   if (!g_io_stream_is_closed (io_stream))
 297     {
 298       g_warning ("stream is not closed yet, can't get etag");
 299       return NULL;
 300     }
 301
 302   etag = NULL;
 303
 304   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 305   if (class->get_etag)
 306     etag = class->get_etag (stream);
 307
 308   return etag;
 309 }
 310
 311 static goffset
 312 g_file_io_stream_tell (GFileIOStream  *stream)
 313 {
 314   GFileIOStreamClass *class;
 315   goffset offset;
 316
 317   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), 0);
 318
 319   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 320
 321   offset = 0;
 322   if (class->tell)
 323     offset = class->tell (stream);
 324
 325   return offset;
 326 }
 327
 328 static goffset
 329 g_file_io_stream_seekable_tell (GSeekable *seekable)
 330 {
 331   return g_file_io_stream_tell (G_FILE_IO_STREAM (seekable));
 332 }
 333
 334 static gboolean
 335 g_file_io_stream_can_seek (GFileIOStream  *stream)
 336 {
 337   GFileIOStreamClass *class;
 338   gboolean can_seek;
 339
 340   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 341
 342   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 343
 344   can_seek = FALSE;
 345   if (class->seek)
 346     {
 347       can_seek = TRUE;
 348       if (class->can_seek)
 349         can_seek = class->can_seek (stream);
 350     }
 351
 352   return can_seek;
 353 }
 354
 355 static gboolean
 356 g_file_io_stream_seekable_can_seek (GSeekable *seekable)
 357 {
 358   return g_file_io_stream_can_seek (G_FILE_IO_STREAM (seekable));
 359 }
 360
 361 static gboolean
 362 g_file_io_stream_seek (GFileIOStream  *stream,
 363                        goffset             offset,
 364                        GSeekType           type,
 365                        GCancellable       *cancellable,
 366                        GError            **error)
 367 {
 368   GFileIOStreamClass *class;
 369   GIOStream *io_stream;
 370   gboolean res;
 371
 372   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 373
 374   io_stream = G_IO_STREAM (stream);
 375   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 376
 377   if (!class->seek)
 378     {
 379       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 380                            _("Seek not supported on stream"));
 381       return FALSE;
 382     }
 383
 384   if (!g_io_stream_set_pending (io_stream, error))
 385     return FALSE;
 386
 387   if (cancellable)
 388     g_cancellable_push_current (cancellable);
 389
 390   res = class->seek (stream, offset, type, cancellable, error);
 391
 392   if (cancellable)
 393     g_cancellable_pop_current (cancellable);
 394
 395   g_io_stream_clear_pending (io_stream);
 396
 397   return res;
 398 }
 399
 400 static gboolean
 401 g_file_io_stream_seekable_seek (GSeekable  *seekable,
 402                                     goffset     offset,
 403                                     GSeekType   type,
 404                                     GCancellable  *cancellable,
 405                                     GError    **error)
 406 {
 407   return g_file_io_stream_seek (G_FILE_IO_STREAM (seekable),
 408                                 offset, type, cancellable, error);
 409 }
 410
 411 static gboolean
 412 g_file_io_stream_can_truncate (GFileIOStream  *stream)
 413 {
 414   GFileIOStreamClass *class;
 415   gboolean can_truncate;
 416
 417   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 418
 419   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 420
 421   can_truncate = FALSE;
 422   if (class->truncate_fn)
 423     {
 424       can_truncate = TRUE;
 425       if (class->can_truncate)
 426         can_truncate = class->can_truncate (stream);
 427     }
 428
 429   return can_truncate;
 430 }
 431
 432 static gboolean
 433 g_file_io_stream_seekable_can_truncate (GSeekable  *seekable)
 434 {
 435   return g_file_io_stream_can_truncate (G_FILE_IO_STREAM (seekable));
 436 }
 437
 438 static gboolean
 439 g_file_io_stream_truncate (GFileIOStream  *stream,
 440                            goffset             size,
 441                            GCancellable       *cancellable,
 442                            GError            **error)
 443 {
 444   GFileIOStreamClass *class;
 445   GIOStream *io_stream;
 446   gboolean res;
 447
 448   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 449
 450   io_stream = G_IO_STREAM (stream);
 451   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 452
 453   if (!class->truncate_fn)
 454     {
 455       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 456                            _("Truncate not supported on stream"));
 457       return FALSE;
 458     }
 459
 460   if (!g_io_stream_set_pending (io_stream, error))
 461     return FALSE;
 462
 463   if (cancellable)
 464     g_cancellable_push_current (cancellable);
 465
 466   res = class->truncate_fn (stream, size, cancellable, error);
 467
 468   if (cancellable)
 469     g_cancellable_pop_current (cancellable);
 470
 471   g_io_stream_clear_pending (io_stream);
 472
 473   return res;
 474 }
 475
 476 static gboolean
 477 g_file_io_stream_seekable_truncate (GSeekable     *seekable,
 478                                     goffset        size,
 479                                     GCancellable  *cancellable,
 480                                     GError       **error)
 481 {
 482   return g_file_io_stream_truncate (G_FILE_IO_STREAM (seekable),
 483                                         size, cancellable, error);
 484 }
 485 /*****************************************************
 486  *   Default implementations based on output stream  *
 487  *****************************************************/
 488
 489 static goffset
 490 g_file_io_stream_real_tell (GFileIOStream    *stream)
 491 {
 492   GOutputStream *out;
 493   GSeekable *seekable;
 494
 495   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 496   seekable = G_SEEKABLE (out);
 497
 498   return g_seekable_tell (seekable);
 499 }
 500
 501 static gboolean
 502 g_file_io_stream_real_can_seek (GFileIOStream    *stream)
 503 {
 504   GOutputStream *out;
 505   GSeekable *seekable;
 506
 507   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 508   seekable = G_SEEKABLE (out);
 509
 510   return g_seekable_can_seek (seekable);
 511 }
 512
 513 static gboolean
 514 g_file_io_stream_real_seek (GFileIOStream    *stream,
 515                             goffset           offset,
 516                             GSeekType         type,
 517                             GCancellable     *cancellable,
 518                             GError          **error)
 519 {
 520   GOutputStream *out;
 521   GSeekable *seekable;
 522
 523   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 524   seekable = G_SEEKABLE (out);
 525
 526   return g_seekable_seek (seekable, offset, type, cancellable, error);
 527 }
 528
 529 static  gboolean
 530 g_file_io_stream_real_can_truncate (GFileIOStream    *stream)
 531 {
 532   GOutputStream *out;
 533   GSeekable *seekable;
 534
 535   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 536   seekable = G_SEEKABLE (out);
 537
 538   return g_seekable_can_truncate (seekable);
 539 }
 540
 541 static gboolean
 542 g_file_io_stream_real_truncate_fn (GFileIOStream    *stream,
 543                                    goffset               size,
 544                                    GCancellable         *cancellable,
 545                                    GError              **error)
 546 {
 547   GOutputStream *out;
 548   GSeekable *seekable;
 549
 550   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 551   seekable = G_SEEKABLE (out);
 552
 553   return g_seekable_truncate (seekable, size, cancellable, error);
 554 }
 555
 556 static char *
 557 g_file_io_stream_real_get_etag (GFileIOStream    *stream)
 558 {
 559   GOutputStream *out;
 560   GFileOutputStream *file_out;
 561
 562   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 563   file_out = G_FILE_OUTPUT_STREAM (out);
 564
 565   return g_file_output_stream_get_etag (file_out);
 566 }
 567
 568 static GFileInfo *
 569 g_file_io_stream_real_query_info (GFileIOStream    *stream,
 570                                   const char           *attributes,
 571                                   GCancellable         *cancellable,
 572                                   GError              **error)
 573 {
 574   GOutputStream *out;
 575   GFileOutputStream *file_out;
 576
 577   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 578   file_out = G_FILE_OUTPUT_STREAM (out);
 579
 580   return g_file_output_stream_query_info (file_out,
 581                                           attributes, cancellable, error);
 582 }
 583
 584 typedef struct {
 585   GObject *object;
 586   GAsyncReadyCallback callback;
 587   gpointer user_data;
 588 } AsyncOpWrapper;
 589
 590 static AsyncOpWrapper *
 591 async_op_wrapper_new (gpointer object,
 592                       GAsyncReadyCallback callback,
 593                       gpointer user_data)
 594 {
 595   AsyncOpWrapper *data;
 596
 597   data = g_new0 (AsyncOpWrapper, 1);
 598   data->object = g_object_ref (object);
 599   data->callback = callback;
 600   data->user_data = user_data;
 601
 602   return data;
 603 }
 604
 605 static void
 606 async_op_wrapper_callback (GObject *source_object,
 607                            GAsyncResult *res,
 608                            gpointer user_data)
 609 {
 610   AsyncOpWrapper *data  = user_data;
 611   data->callback (data->object, res, data->user_data);
 612   g_object_unref (data->object);
 613   g_free (data);
 614 }
 615
 616 static void
 617 g_file_io_stream_real_query_info_async (GFileIOStream     *stream,
 618                                         const char           *attributes,
 619                                         int                   io_priority,
 620                                         GCancellable         *cancellable,
 621                                         GAsyncReadyCallback   callback,
 622                                         gpointer              user_data)
 623 {
 624   GOutputStream *out;
 625   GFileOutputStream *file_out;
 626   AsyncOpWrapper *data;
 627
 628   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 629   file_out = G_FILE_OUTPUT_STREAM (out);
 630
 631   data = async_op_wrapper_new (stream, callback, user_data);
 632   g_file_output_stream_query_info_async (file_out,
 633                                          attributes, io_priority,
 634                                          cancellable, async_op_wrapper_callback, data);
 635 }
 636
 637 static GFileInfo *
 638 g_file_io_stream_real_query_info_finish (GFileIOStream     *stream,
 639                                          GAsyncResult      *res,
 640                                          GError           **error)
 641 {
 642   GOutputStream *out;
 643   GFileOutputStream *file_out;
 644
 645   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 646   file_out = G_FILE_OUTPUT_STREAM (out);
 647
 648   return g_file_output_stream_query_info_finish (file_out, res, error);
 649 }
 650
 651 static void
 652 g_file_io_stream_class_init (GFileIOStreamClass *klass)
 653 {
 654   klass->tell = g_file_io_stream_real_tell;
 655   klass->can_seek = g_file_io_stream_real_can_seek;
 656   klass->seek = g_file_io_stream_real_seek;
 657   klass->can_truncate = g_file_io_stream_real_can_truncate;
 658   klass->truncate_fn = g_file_io_stream_real_truncate_fn;
 659   klass->query_info = g_file_io_stream_real_query_info;
 660   klass->query_info_async = g_file_io_stream_real_query_info_async;
 661   klass->query_info_finish = g_file_io_stream_real_query_info_finish;
 662   klass->get_etag = g_file_io_stream_real_get_etag;
 663 }