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 #include "gioalias.h"
  36
  37 /**
  38  * SECTION:gfileiostream
  39  * @short_description:  File read and write streaming operations
  40  * @include: gio/gio.h
  41  * @see_also: #GIOStream, #GFileInputStream, #GFileOutputStream, #GSeekable
  42  *
  43  * GFileIOStream provides io streams that both read and write to the same
  44  * file handle.
  45  *
  46  * GFileIOStream implements #GSeekable, which allows the io
  47  * stream to jump to arbitrary positions in the file and to truncate
  48  * the file, provided the filesystem of the file supports these
  49  * operations.
  50  *
  51  * To find the position of a file io stream, use
  52  * g_seekable_tell().
  53  *
  54  * To find out if a file io stream supports seeking, use g_seekable_can_seek().
  55  * To position a file io stream, use g_seekable_seek().
  56  * To find out if a file io stream supports truncating, use
  57  * g_seekable_can_truncate(). To truncate a file io
  58  * stream, use g_seekable_truncate().
  59  *
  60  * The default implementation of all the #GFileIOStream operations
  61  * and the implementation of #GSeekable just call into the same operations
  62  * on the output stream.
  63  * Since: 2.22
  64  **/
  65
  66 static void       g_file_io_stream_seekable_iface_init    (GSeekableIface       *iface);
  67 static goffset    g_file_io_stream_seekable_tell          (GSeekable            *seekable);
  68 static gboolean   g_file_io_stream_seekable_can_seek      (GSeekable            *seekable);
  69 static gboolean   g_file_io_stream_seekable_seek          (GSeekable            *seekable,
  70                                                            goffset               offset,
  71                                                            GSeekType             type,
  72                                                            GCancellable         *cancellable,
  73                                                            GError              **error);
  74 static gboolean   g_file_io_stream_seekable_can_truncate  (GSeekable            *seekable);
  75 static gboolean   g_file_io_stream_seekable_truncate      (GSeekable            *seekable,
  76                                                            goffset               offset,
  77                                                            GCancellable         *cancellable,
  78                                                            GError              **error);
  79 static void       g_file_io_stream_real_query_info_async  (GFileIOStream    *stream,
  80                                                            const char           *attributes,
  81                                                            int                   io_priority,
  82                                                            GCancellable         *cancellable,
  83                                                            GAsyncReadyCallback   callback,
  84                                                            gpointer              user_data);
  85 static GFileInfo *g_file_io_stream_real_query_info_finish (GFileIOStream    *stream,
  86                                                            GAsyncResult         *result,
  87                                                            GError              **error);
  88
  89 G_DEFINE_TYPE_WITH_CODE (GFileIOStream, g_file_io_stream, G_TYPE_IO_STREAM,
  90                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  91                                                 g_file_io_stream_seekable_iface_init));
  92
  93 struct _GFileIOStreamPrivate {
  94   GAsyncReadyCallback outstanding_callback;
  95 };
  96
  97 static void
  98 g_file_io_stream_seekable_iface_init (GSeekableIface *iface)
  99 {
 100   iface->tell = g_file_io_stream_seekable_tell;
 101   iface->can_seek = g_file_io_stream_seekable_can_seek;
 102   iface->seek = g_file_io_stream_seekable_seek;
 103   iface->can_truncate = g_file_io_stream_seekable_can_truncate;
 104   iface->truncate_fn = g_file_io_stream_seekable_truncate;
 105 }
 106
 107 static void
 108 g_file_io_stream_init (GFileIOStream *stream)
 109 {
 110   stream->priv = G_TYPE_INSTANCE_GET_PRIVATE (stream,
 111                                               G_TYPE_FILE_IO_STREAM,
 112                                               GFileIOStreamPrivate);
 113 }
 114
 115 /**
 116  * g_file_io_stream_query_info:
 117  * @stream: a #GFileIOStream.
 118  * @attributes: a file attribute query string.
 119  * @cancellable: optional #GCancellable object, %NULL to ignore.
 120  * @error: a #GError, %NULL to ignore.
 121  *
 122  * Queries a file io stream for the given @attributes.
 123  * This function blocks while querying the stream. For the asynchronous
 124  * version of this function, see g_file_io_stream_query_info_async().
 125  * While the stream is blocked, the stream will set the pending flag
 126  * internally, and any other operations on the stream will fail with
 127  * %G_IO_ERROR_PENDING.
 128  *
 129  * Can fail if the stream was already closed (with @error being set to
 130  * %G_IO_ERROR_CLOSED), the stream has pending operations (with @error being
 131  * set to %G_IO_ERROR_PENDING), or if querying info is not supported for
 132  * the stream's interface (with @error being set to %G_IO_ERROR_NOT_SUPPORTED). I
 133  * all cases of failure, %NULL will be returned.
 134  *
 135  * If @cancellable is not %NULL, then the operation can be cancelled by
 136  * triggering the cancellable object from another thread. If the operation
 137  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set, and %NULL will
 138  * be returned.
 139  *
 140  * Returns: a #GFileInfo for the @stream, or %NULL on error.
 141  *
 142  * Since: 2.22
 143  **/
 144 GFileInfo *
 145 g_file_io_stream_query_info (GFileIOStream      *stream,
 146                              const char             *attributes,
 147                              GCancellable           *cancellable,
 148                              GError                **error)
 149 {
 150   GFileIOStreamClass *class;
 151   GIOStream *io_stream;
 152   GFileInfo *info;
 153
 154   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 155
 156   io_stream = G_IO_STREAM (stream);
 157
 158   if (!g_io_stream_set_pending (io_stream, error))
 159     return NULL;
 160
 161   info = NULL;
 162
 163   if (cancellable)
 164     g_cancellable_push_current (cancellable);
 165
 166   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 167   if (class->query_info)
 168     info = class->query_info (stream, attributes, cancellable, error);
 169   else
 170     g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 171                          _("Stream doesn't support query_info"));
 172
 173   if (cancellable)
 174     g_cancellable_pop_current (cancellable);
 175
 176   g_io_stream_clear_pending (io_stream);
 177
 178   return info;
 179 }
 180
 181 static void
 182 async_ready_callback_wrapper (GObject *source_object,
 183                               GAsyncResult *res,
 184                               gpointer      user_data)
 185 {
 186   GFileIOStream *stream = G_FILE_IO_STREAM (source_object);
 187
 188   g_io_stream_clear_pending (G_IO_STREAM (stream));
 189   if (stream->priv->outstanding_callback)
 190     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 191   g_object_unref (stream);
 192 }
 193
 194 /**
 195  * g_file_io_stream_query_info_async:
 196  * @stream: a #GFileIOStream.
 197  * @attributes: a file attribute query string.
 198  * @io_priority: the <link linkend="gio-GIOScheduler">I/O priority</link>
 199  *     of the request.
 200  * @cancellable: optional #GCancellable object, %NULL to ignore.
 201  * @callback: callback to call when the request is satisfied
 202  * @user_data: the data to pass to callback function
 203  *
 204  * Asynchronously queries the @stream for a #GFileInfo. When completed,
 205  * @callback will be called with a #GAsyncResult which can be used to
 206  * finish the operation with g_file_io_stream_query_info_finish().
 207  *
 208  * For the synchronous version of this function, see
 209  * g_file_io_stream_query_info().
 210  *
 211  * Since: 2.22
 212  **/
 213 void
 214 g_file_io_stream_query_info_async (GFileIOStream     *stream,
 215                                           const char           *attributes,
 216                                           int                   io_priority,
 217                                           GCancellable         *cancellable,
 218                                           GAsyncReadyCallback   callback,
 219                                           gpointer              user_data)
 220 {
 221   GFileIOStreamClass *klass;
 222   GIOStream *io_stream;
 223   GError *error = NULL;
 224
 225   g_return_if_fail (G_IS_FILE_IO_STREAM (stream));
 226
 227   io_stream = G_IO_STREAM (stream);
 228
 229   if (!g_io_stream_set_pending (io_stream, &error))
 230     {
 231       g_simple_async_report_gerror_in_idle (G_OBJECT (stream),
 232                                             callback,
 233                                             user_data,
 234                                             error);
 235       g_error_free (error);
 236       return;
 237     }
 238
 239   klass = G_FILE_IO_STREAM_GET_CLASS (stream);
 240
 241   stream->priv->outstanding_callback = callback;
 242   g_object_ref (stream);
 243   klass->query_info_async (stream, attributes, io_priority, cancellable,
 244                               async_ready_callback_wrapper, user_data);
 245 }
 246
 247 /**
 248  * g_file_io_stream_query_info_finish:
 249  * @stream: a #GFileIOStream.
 250  * @result: a #GAsyncResult.
 251  * @error: a #GError, %NULL to ignore.
 252  *
 253  * Finalizes the asynchronous query started
 254  * by g_file_io_stream_query_info_async().
 255  *
 256  * Returns: A #GFileInfo for the finished query.
 257  *
 258  * Since: 2.22
 259  **/
 260 GFileInfo *
 261 g_file_io_stream_query_info_finish (GFileIOStream     *stream,
 262                                            GAsyncResult         *result,
 263                                            GError              **error)
 264 {
 265   GSimpleAsyncResult *simple;
 266   GFileIOStreamClass *class;
 267
 268   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 269   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 270
 271   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 272     {
 273       simple = G_SIMPLE_ASYNC_RESULT (result);
 274       if (g_simple_async_result_propagate_error (simple, error))
 275         return NULL;
 276     }
 277
 278   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 279   return class->query_info_finish (stream, result, error);
 280 }
 281
 282 /**
 283  * g_file_io_stream_get_etag:
 284  * @stream: a #GFileIOStream.
 285  *
 286  * Gets the entity tag for the file when it has been written.
 287  * This must be called after the stream has been written
 288  * and closed, as the etag can change while writing.
 289  *
 290  * Returns: the entity tag for the stream.
 291  *
 292  * Since: 2.22
 293  **/
 294 char *
 295 g_file_io_stream_get_etag (GFileIOStream  *stream)
 296 {
 297   GFileIOStreamClass *class;
 298   GIOStream *io_stream;
 299   char *etag;
 300
 301   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), NULL);
 302
 303   io_stream = G_IO_STREAM (stream);
 304
 305   if (!g_io_stream_is_closed (io_stream))
 306     {
 307       g_warning ("stream is not closed yet, can't get etag");
 308       return NULL;
 309     }
 310
 311   etag = NULL;
 312
 313   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 314   if (class->get_etag)
 315     etag = class->get_etag (stream);
 316
 317   return etag;
 318 }
 319
 320 static goffset
 321 g_file_io_stream_tell (GFileIOStream  *stream)
 322 {
 323   GFileIOStreamClass *class;
 324   goffset offset;
 325
 326   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), 0);
 327
 328   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 329
 330   offset = 0;
 331   if (class->tell)
 332     offset = class->tell (stream);
 333
 334   return offset;
 335 }
 336
 337 static goffset
 338 g_file_io_stream_seekable_tell (GSeekable *seekable)
 339 {
 340   return g_file_io_stream_tell (G_FILE_IO_STREAM (seekable));
 341 }
 342
 343 static gboolean
 344 g_file_io_stream_can_seek (GFileIOStream  *stream)
 345 {
 346   GFileIOStreamClass *class;
 347   gboolean can_seek;
 348
 349   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 350
 351   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 352
 353   can_seek = FALSE;
 354   if (class->seek)
 355     {
 356       can_seek = TRUE;
 357       if (class->can_seek)
 358         can_seek = class->can_seek (stream);
 359     }
 360
 361   return can_seek;
 362 }
 363
 364 static gboolean
 365 g_file_io_stream_seekable_can_seek (GSeekable *seekable)
 366 {
 367   return g_file_io_stream_can_seek (G_FILE_IO_STREAM (seekable));
 368 }
 369
 370 static gboolean
 371 g_file_io_stream_seek (GFileIOStream  *stream,
 372                        goffset             offset,
 373                        GSeekType           type,
 374                        GCancellable       *cancellable,
 375                        GError            **error)
 376 {
 377   GFileIOStreamClass *class;
 378   GIOStream *io_stream;
 379   gboolean res;
 380
 381   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 382
 383   io_stream = G_IO_STREAM (stream);
 384   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 385
 386   if (!class->seek)
 387     {
 388       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 389                            _("Seek not supported on stream"));
 390       return FALSE;
 391     }
 392
 393   if (!g_io_stream_set_pending (io_stream, error))
 394     return FALSE;
 395
 396   if (cancellable)
 397     g_cancellable_push_current (cancellable);
 398
 399   res = class->seek (stream, offset, type, cancellable, error);
 400
 401   if (cancellable)
 402     g_cancellable_pop_current (cancellable);
 403
 404   g_io_stream_clear_pending (io_stream);
 405
 406   return res;
 407 }
 408
 409 static gboolean
 410 g_file_io_stream_seekable_seek (GSeekable  *seekable,
 411                                     goffset     offset,
 412                                     GSeekType   type,
 413                                     GCancellable  *cancellable,
 414                                     GError    **error)
 415 {
 416   return g_file_io_stream_seek (G_FILE_IO_STREAM (seekable),
 417                                 offset, type, cancellable, error);
 418 }
 419
 420 static gboolean
 421 g_file_io_stream_can_truncate (GFileIOStream  *stream)
 422 {
 423   GFileIOStreamClass *class;
 424   gboolean can_truncate;
 425
 426   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 427
 428   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 429
 430   can_truncate = FALSE;
 431   if (class->truncate_fn)
 432     {
 433       can_truncate = TRUE;
 434       if (class->can_truncate)
 435         can_truncate = class->can_truncate (stream);
 436     }
 437
 438   return can_truncate;
 439 }
 440
 441 static gboolean
 442 g_file_io_stream_seekable_can_truncate (GSeekable  *seekable)
 443 {
 444   return g_file_io_stream_can_truncate (G_FILE_IO_STREAM (seekable));
 445 }
 446
 447 static gboolean
 448 g_file_io_stream_truncate (GFileIOStream  *stream,
 449                            goffset             size,
 450                            GCancellable       *cancellable,
 451                            GError            **error)
 452 {
 453   GFileIOStreamClass *class;
 454   GIOStream *io_stream;
 455   gboolean res;
 456
 457   g_return_val_if_fail (G_IS_FILE_IO_STREAM (stream), FALSE);
 458
 459   io_stream = G_IO_STREAM (stream);
 460   class = G_FILE_IO_STREAM_GET_CLASS (stream);
 461
 462   if (!class->truncate_fn)
 463     {
 464       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 465                            _("Truncate not supported on stream"));
 466       return FALSE;
 467     }
 468
 469   if (!g_io_stream_set_pending (io_stream, error))
 470     return FALSE;
 471
 472   if (cancellable)
 473     g_cancellable_push_current (cancellable);
 474
 475   res = class->truncate_fn (stream, size, cancellable, error);
 476
 477   if (cancellable)
 478     g_cancellable_pop_current (cancellable);
 479
 480   g_io_stream_clear_pending (io_stream);
 481
 482   return res;
 483 }
 484
 485 static gboolean
 486 g_file_io_stream_seekable_truncate (GSeekable     *seekable,
 487                                     goffset        size,
 488                                     GCancellable  *cancellable,
 489                                     GError       **error)
 490 {
 491   return g_file_io_stream_truncate (G_FILE_IO_STREAM (seekable),
 492                                         size, cancellable, error);
 493 }
 494 /*****************************************************
 495  *   Default implementations based on output stream  *
 496  *****************************************************/
 497
 498 static goffset
 499 g_file_io_stream_real_tell (GFileIOStream    *stream)
 500 {
 501   GOutputStream *out;
 502   GSeekable *seekable;
 503
 504   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 505   seekable = G_SEEKABLE (out);
 506
 507   return g_seekable_tell (seekable);
 508 }
 509
 510 static gboolean
 511 g_file_io_stream_real_can_seek (GFileIOStream    *stream)
 512 {
 513   GOutputStream *out;
 514   GSeekable *seekable;
 515
 516   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 517   seekable = G_SEEKABLE (out);
 518
 519   return g_seekable_can_seek (seekable);
 520 }
 521
 522 static gboolean
 523 g_file_io_stream_real_seek (GFileIOStream    *stream,
 524                             goffset           offset,
 525                             GSeekType         type,
 526                             GCancellable     *cancellable,
 527                             GError          **error)
 528 {
 529   GOutputStream *out;
 530   GSeekable *seekable;
 531
 532   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 533   seekable = G_SEEKABLE (out);
 534
 535   return g_seekable_seek (seekable, offset, type, cancellable, error);
 536 }
 537
 538 static  gboolean
 539 g_file_io_stream_real_can_truncate (GFileIOStream    *stream)
 540 {
 541   GOutputStream *out;
 542   GSeekable *seekable;
 543
 544   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 545   seekable = G_SEEKABLE (out);
 546
 547   return g_seekable_can_truncate (seekable);
 548 }
 549
 550 static gboolean
 551 g_file_io_stream_real_truncate_fn (GFileIOStream    *stream,
 552                                    goffset               size,
 553                                    GCancellable         *cancellable,
 554                                    GError              **error)
 555 {
 556   GOutputStream *out;
 557   GSeekable *seekable;
 558
 559   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 560   seekable = G_SEEKABLE (out);
 561
 562   return g_seekable_truncate (seekable, size, cancellable, error);
 563 }
 564
 565 static char *
 566 g_file_io_stream_real_get_etag (GFileIOStream    *stream)
 567 {
 568   GOutputStream *out;
 569   GFileOutputStream *file_out;
 570
 571   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 572   file_out = G_FILE_OUTPUT_STREAM (out);
 573
 574   return g_file_output_stream_get_etag (file_out);
 575 }
 576
 577 static GFileInfo *
 578 g_file_io_stream_real_query_info (GFileIOStream    *stream,
 579                                   const char           *attributes,
 580                                   GCancellable         *cancellable,
 581                                   GError              **error)
 582 {
 583   GOutputStream *out;
 584   GFileOutputStream *file_out;
 585
 586   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 587   file_out = G_FILE_OUTPUT_STREAM (out);
 588
 589   return g_file_output_stream_query_info (file_out,
 590                                           attributes, cancellable, error);
 591 }
 592
 593 typedef struct {
 594   GObject *object;
 595   GAsyncReadyCallback callback;
 596   gpointer user_data;
 597 } AsyncOpWrapper;
 598
 599 static AsyncOpWrapper *
 600 async_op_wrapper_new (gpointer object,
 601                       GAsyncReadyCallback callback,
 602                       gpointer user_data)
 603 {
 604   AsyncOpWrapper *data;
 605
 606   data = g_new0 (AsyncOpWrapper, 1);
 607   data->object = g_object_ref (object);
 608   data->callback = callback;
 609   data->user_data = user_data;
 610
 611   return data;
 612 }
 613
 614 static void
 615 async_op_wrapper_callback (GObject *source_object,
 616                            GAsyncResult *res,
 617                            gpointer user_data)
 618 {
 619   AsyncOpWrapper *data  = user_data;
 620   data->callback (data->object, res, data->user_data);
 621   g_object_unref (data->object);
 622   g_free (data);
 623 }
 624
 625 static void
 626 g_file_io_stream_real_query_info_async (GFileIOStream     *stream,
 627                                         const char           *attributes,
 628                                         int                   io_priority,
 629                                         GCancellable         *cancellable,
 630                                         GAsyncReadyCallback   callback,
 631                                         gpointer              user_data)
 632 {
 633   GOutputStream *out;
 634   GFileOutputStream *file_out;
 635   AsyncOpWrapper *data;
 636
 637   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 638   file_out = G_FILE_OUTPUT_STREAM (out);
 639
 640   data = async_op_wrapper_new (stream, callback, user_data);
 641   g_file_output_stream_query_info_async (file_out,
 642                                          attributes, io_priority,
 643                                          cancellable, async_op_wrapper_callback, data);
 644 }
 645
 646 static GFileInfo *
 647 g_file_io_stream_real_query_info_finish (GFileIOStream     *stream,
 648                                          GAsyncResult      *res,
 649                                          GError           **error)
 650 {
 651   GOutputStream *out;
 652   GFileOutputStream *file_out;
 653
 654   out = g_io_stream_get_output_stream (G_IO_STREAM (stream));
 655   file_out = G_FILE_OUTPUT_STREAM (out);
 656
 657   return g_file_output_stream_query_info_finish (file_out, res, error);
 658 }
 659
 660 static void
 661 g_file_io_stream_class_init (GFileIOStreamClass *klass)
 662 {
 663   g_type_class_add_private (klass, sizeof (GFileIOStreamPrivate));
 664
 665   klass->tell = g_file_io_stream_real_tell;
 666   klass->can_seek = g_file_io_stream_real_can_seek;
 667   klass->seek = g_file_io_stream_real_seek;
 668   klass->can_truncate = g_file_io_stream_real_can_truncate;
 669   klass->truncate_fn = g_file_io_stream_real_truncate_fn;
 670   klass->query_info = g_file_io_stream_real_query_info;
 671   klass->query_info_async = g_file_io_stream_real_query_info_async;
 672   klass->query_info_finish = g_file_io_stream_real_query_info_finish;
 673   klass->get_etag = g_file_io_stream_real_get_etag;
 674 }
 675
 676 #define __G_FILE_IO_STREAM_C__
 677 #include "gioaliasdef.c"