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: 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: optional #GCancellable object, %NULL to ignore.
 200  * @callback: callback to call when the request is satisfied
 201  * @user_data: 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_gerror_in_idle (G_OBJECT (stream),
 231                                             callback,
 232                                             user_data,
 233                                             error);
 234       g_error_free (error);
 235       return;
 236     }
 237
 238   klass = G_FILE_IO_STREAM_GET_CLASS (stream);
 239
 240   stream->priv->outstanding_callback = callback;
 241   g_object_ref (stream);
 242   klass->query_info_async (stream, attributes, io_priority, cancellable,
 243                               async_ready_callback_wrapper, user_data);
 244 }
 245
 246 /**
 247  * g_file_io_stream_query_info_finish:
 248  * @stream: a #GFileIOStream.
 249  * @result: a #GAsyncResult.
 250  * @error: a #GError, %NULL to ignore.
 251  *
 252  * Finalizes the asynchronous query started
 253  * by g_file_io_stream_query_info_async().
 254  *
 255  * Returns: (transfer full): A #GFileInfo for the finished query.
 256  *
 257  * Since: 2.22
 258  **/
 259 GFileInfo *
 260 g_file_io_stream_query_info_finish (GFileIOStream     *stream,
 261                                            GAsyncResult         *result,
 262                                            GError              **error)
 263 {
 264   GSimpleAsyncResult *simple;
 265   GFileIOStreamClass *class;
 266
 267   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 268   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 269
 270   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 271     {
 272       simple = G_SIMPLE_ASYNC_RESULT (result);
 273       if (g_simple_async_result_propagate_error (simple, error))
 274         return NULL;
 275     }
 276
 277   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 278   return class->query_info_finish (stream, result, error);
 279 }
 280
 281 /**
 282  * g_file_io_stream_get_etag:
 283  * @stream: a #GFileIOStream.
 284  *
 285  * Gets the entity tag for the file when it has been written.
 286  * This must be called after the stream has been written
 287  * and closed, as the etag can change while writing.
 288  *
 289  * Returns: the entity tag for the stream.
 290  *
 291  * Since: 2.22
 292  **/
 293 char *
 294 g_file_io_stream_get_etag (GFileIOStream  *stream)
 295 {
 296   GFileIOStreamClass *class;
 297   GIOStream *io_stream;
 298   char *etag;
 299
 300   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 301
 302   io_stream = G_IO_STREAM (stream);
 303
 304   if (!g_io_stream_is_closed (io_stream))
 305     {
 306       g_warning ("stream is not closed yet, can't get etag");
 307       return NULL;
 308     }
 309
 310   etag = NULL;
 311
 312   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 313   if (class->get_etag)
 314     etag = class->get_etag (stream);
 315
 316   return etag;
 317 }
 318
 319 static goffset
 320 g_file_io_stream_tell (GFileIOStream  *stream)
 321 {
 322   GFileIOStreamClass *class;
 323   goffset offset;
 324
 325   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), 0);
 326
 327   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 328
 329   offset = 0;
 330   if (class->tell)
 331     offset = class->tell (stream);
 332
 333   return offset;
 334 }
 335
 336 static goffset
 337 g_file_io_stream_seekable_tell (GSeekable *seekable)
 338 {
 339   return g_file_io_stream_tell (G_FILE_IO_STREAM (seekable));
 340 }
 341
 342 static gboolean
 343 g_file_io_stream_can_seek (GFileIOStream  *stream)
 344 {
 345   GFileIOStreamClass *class;
 346   gboolean can_seek;
 347
 348   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 349
 350   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 351
 352   can_seek = FALSE;
 353   if (class->seek)
 354     {
 355       can_seek = TRUE;
 356       if (class->can_seek)
 357         can_seek = class->can_seek (stream);
 358     }
 359
 360   return can_seek;
 361 }
 362
 363 static gboolean
 364 g_file_io_stream_seekable_can_seek (GSeekable *seekable)
 365 {
 366   return g_file_io_stream_can_seek (G_FILE_IO_STREAM (seekable));
 367 }
 368
 369 static gboolean
 370 g_file_io_stream_seek (GFileIOStream  *stream,
 371                        goffset             offset,
 372                        GSeekType           type,
 373                        GCancellable       *cancellable,
 374                        GError            **error)
 375 {
 376   GFileIOStreamClass *class;
 377   GIOStream *io_stream;
 378   gboolean res;
 379
 380   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 381
 382   io_stream = G_IO_STREAM (stream);
 383   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 384
 385   if (!class->seek)
 386     {
 387       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 388                            _("Seek not supported on stream"));
 389       return FALSE;
 390     }
 391
 392   if (!g_io_stream_set_pending (io_stream, error))
 393     return FALSE;
 394
 395   if (cancellable)
 396     g_cancellable_push_current (cancellable);
 397
 398   res = class->seek (stream, offset, type, cancellable, error);
 399
 400   if (cancellable)
 401     g_cancellable_pop_current (cancellable);
 402
 403   g_io_stream_clear_pending (io_stream);
 404
 405   return res;
 406 }
 407
 408 static gboolean
 409 g_file_io_stream_seekable_seek (GSeekable  *seekable,
 410                                     goffset     offset,
 411                                     GSeekType   type,
 412                                     GCancellable  *cancellable,
 413                                     GError    **error)
 414 {
 415   return g_file_io_stream_seek (G_FILE_IO_STREAM (seekable),
 416                                 offset, type, cancellable, error);
 417 }
 418
 419 static gboolean
 420 g_file_io_stream_can_truncate (GFileIOStream  *stream)
 421 {
 422   GFileIOStreamClass *class;
 423   gboolean can_truncate;
 424
 425   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 426
 427   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 428
 429   can_truncate = FALSE;
 430   if (class->truncate_fn)
 431     {
 432       can_truncate = TRUE;
 433       if (class->can_truncate)
 434         can_truncate = class->can_truncate (stream);
 435     }
 436
 437   return can_truncate;
 438 }
 439
 440 static gboolean
 441 g_file_io_stream_seekable_can_truncate (GSeekable  *seekable)
 442 {
 443   return g_file_io_stream_can_truncate (G_FILE_IO_STREAM (seekable));
 444 }
 445
 446 static gboolean
 447 g_file_io_stream_truncate (GFileIOStream  *stream,
 448                            goffset             size,
 449                            GCancellable       *cancellable,
 450                            GError            **error)
 451 {
 452   GFileIOStreamClass *class;
 453   GIOStream *io_stream;
 454   gboolean res;
 455
 456   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 457
 458   io_stream = G_IO_STREAM (stream);
 459   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 460
 461   if (!class->truncate_fn)
 462     {
 463       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 464                            _("Truncate not supported on stream"));
 465       return FALSE;
 466     }
 467
 468   if (!g_io_stream_set_pending (io_stream, error))
 469     return FALSE;
 470
 471   if (cancellable)
 472     g_cancellable_push_current (cancellable);
 473
 474   res = class->truncate_fn (stream, size, cancellable, error);
 475
 476   if (cancellable)
 477     g_cancellable_pop_current (cancellable);
 478
 479   g_io_stream_clear_pending (io_stream);
 480
 481   return res;
 482 }
 483
 484 static gboolean
 485 g_file_io_stream_seekable_truncate (GSeekable     *seekable,
 486                                     goffset        size,
 487                                     GCancellable  *cancellable,
 488                                     GError       **error)
 489 {
 490   return g_file_io_stream_truncate (G_FILE_IO_STREAM (seekable),
 491                                         size, cancellable, error);
 492 }
 493 /*****************************************************
 494  *   Default implementations based on output stream  *
 495  *****************************************************/
 496
 497 static goffset
 498 g_file_io_stream_real_tell (GFileIOStream    *stream)
 499 {
 500   GOutputStream *out;
 501   GSeekable *seekable;
 502
 503   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 504   seekable = G_SEEKABLE (out);
 505
 506   return g_seekable_tell (seekable);
 507 }
 508
 509 static gboolean
 510 g_file_io_stream_real_can_seek (GFileIOStream    *stream)
 511 {
 512   GOutputStream *out;
 513   GSeekable *seekable;
 514
 515   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 516   seekable = G_SEEKABLE (out);
 517
 518   return g_seekable_can_seek (seekable);
 519 }
 520
 521 static gboolean
 522 g_file_io_stream_real_seek (GFileIOStream    *stream,
 523                             goffset           offset,
 524                             GSeekType         type,
 525                             GCancellable     *cancellable,
 526                             GError          **error)
 527 {
 528   GOutputStream *out;
 529   GSeekable *seekable;
 530
 531   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 532   seekable = G_SEEKABLE (out);
 533
 534   return g_seekable_seek (seekable, offset, type, cancellable, error);
 535 }
 536
 537 static  gboolean
 538 g_file_io_stream_real_can_truncate (GFileIOStream    *stream)
 539 {
 540   GOutputStream *out;
 541   GSeekable *seekable;
 542
 543   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 544   seekable = G_SEEKABLE (out);
 545
 546   return g_seekable_can_truncate (seekable);
 547 }
 548
 549 static gboolean
 550 g_file_io_stream_real_truncate_fn (GFileIOStream    *stream,
 551                                    goffset               size,
 552                                    GCancellable         *cancellable,
 553                                    GError              **error)
 554 {
 555   GOutputStream *out;
 556   GSeekable *seekable;
 557
 558   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 559   seekable = G_SEEKABLE (out);
 560
 561   return g_seekable_truncate (seekable, size, cancellable, error);
 562 }
 563
 564 static char *
 565 g_file_io_stream_real_get_etag (GFileIOStream    *stream)
 566 {
 567   GOutputStream *out;
 568   GFileOutputStream *file_out;
 569
 570   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 571   file_out = G_FILE_OUTPUT_STREAM (out);
 572
 573   return g_file_output_stream_get_etag (file_out);
 574 }
 575
 576 static GFileInfo *
 577 g_file_io_stream_real_query_info (GFileIOStream    *stream,
 578                                   const char           *attributes,
 579                                   GCancellable         *cancellable,
 580                                   GError              **error)
 581 {
 582   GOutputStream *out;
 583   GFileOutputStream *file_out;
 584
 585   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 586   file_out = G_FILE_OUTPUT_STREAM (out);
 587
 588   return g_file_output_stream_query_info (file_out,
 589                                           attributes, cancellable, error);
 590 }
 591
 592 typedef struct {
 593   GObject *object;
 594   GAsyncReadyCallback callback;
 595   gpointer user_data;
 596 } AsyncOpWrapper;
 597
 598 static AsyncOpWrapper *
 599 async_op_wrapper_new (gpointer object,
 600                       GAsyncReadyCallback callback,
 601                       gpointer user_data)
 602 {
 603   AsyncOpWrapper *data;
 604
 605   data = g_new0 (AsyncOpWrapper, 1);
 606   data->object = g_object_ref (object);
 607   data->callback = callback;
 608   data->user_data = user_data;
 609
 610   return data;
 611 }
 612
 613 static void
 614 async_op_wrapper_callback (GObject *source_object,
 615                            GAsyncResult *res,
 616                            gpointer user_data)
 617 {
 618   AsyncOpWrapper *data  = user_data;
 619   data->callback (data->object, res, data->user_data);
 620   g_object_unref (data->object);
 621   g_free (data);
 622 }
 623
 624 static void
 625 g_file_io_stream_real_query_info_async (GFileIOStream     *stream,
 626                                         const char           *attributes,
 627                                         int                   io_priority,
 628                                         GCancellable         *cancellable,
 629                                         GAsyncReadyCallback   callback,
 630                                         gpointer              user_data)
 631 {
 632   GOutputStream *out;
 633   GFileOutputStream *file_out;
 634   AsyncOpWrapper *data;
 635
 636   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 637   file_out = G_FILE_OUTPUT_STREAM (out);
 638
 639   data = async_op_wrapper_new (stream, callback, user_data);
 640   g_file_output_stream_query_info_async (file_out,
 641                                          attributes, io_priority,
 642                                          cancellable, async_op_wrapper_callback, data);
 643 }
 644
 645 static GFileInfo *
 646 g_file_io_stream_real_query_info_finish (GFileIOStream     *stream,
 647                                          GAsyncResult      *res,
 648                                          GError           **error)
 649 {
 650   GOutputStream *out;
 651   GFileOutputStream *file_out;
 652
 653   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 654   file_out = G_FILE_OUTPUT_STREAM (out);
 655
 656   return g_file_output_stream_query_info_finish (file_out, res, error);
 657 }
 658
 659 static void
 660 g_file_io_stream_class_init (GFileIOStreamClass *klass)
 661 {
 662   g_type_class_add_private (klass, sizeof (GFileIOStreamPrivate));
 663
 664   klass->tell = g_file_io_stream_real_tell;
 665   klass->can_seek = g_file_io_stream_real_can_seek;
 666   klass->seek = g_file_io_stream_real_seek;
 667   klass->can_truncate = g_file_io_stream_real_can_truncate;
 668   klass->truncate_fn = g_file_io_stream_real_truncate_fn;
 669   klass->query_info = g_file_io_stream_real_query_info;
 670   klass->query_info_async = g_file_io_stream_real_query_info_async;
 671   klass->query_info_finish = g_file_io_stream_real_query_info_finish;
 672   klass->get_etag = g_file_io_stream_real_get_etag;
 673 }