gio/gfileinputstream.c

   1 /* GIO - GLib Input, Output 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 <gfileinputstream.h>
  27 #include <gseekable.h>
  28 #include "gsimpleasyncresult.h"
  29 #include "glibintl.h"
  30
  31 #include "gioalias.h"
  32
  33 /**
  34  * SECTION:gfileinputstream
  35  * @short_description: File input streaming operations
  36  * @include: gio.h
  37  * @see_also: #GInputStream, #GDataInputStream, #GSeekable
  38  *
  39  * GFileInputStream provides input streams that take their
  40  * content from a file.
  41  *
  42  * GFileInputStream implements #GSeekable, which allows the input
  43  * stream to jump to arbitrary positions in the file, provided the
  44  * filesystem of the file allows it. In addition to the generic
  45  * g_seekable_ API, GFileInputStream has its own API for seeking
  46  * and positioning. To find the position of a file input stream,
  47  * use g_file_input_stream_tell(). To find out if a file input
  48  * stream supports seeking, use g_file_input_stream_can_seek().
  49  * To position a file input stream, use g_file_input_stream_seek().
  50  **/
  51
  52 static void       g_file_input_stream_seekable_iface_init    (GSeekableIface       *iface);
  53 static goffset    g_file_input_stream_seekable_tell          (GSeekable            *seekable);
  54 static gboolean   g_file_input_stream_seekable_can_seek      (GSeekable            *seekable);
  55 static gboolean   g_file_input_stream_seekable_seek          (GSeekable            *seekable,
  56                                                               goffset               offset,
  57                                                               GSeekType             type,
  58                                                               GCancellable         *cancellable,
  59                                                               GError              **error);
  60 static gboolean   g_file_input_stream_seekable_can_truncate  (GSeekable            *seekable);
  61 static gboolean   g_file_input_stream_seekable_truncate      (GSeekable            *seekable,
  62                                                               goffset               offset,
  63                                                               GCancellable         *cancellable,
  64                                                               GError              **error);
  65 static void       g_file_input_stream_real_query_info_async  (GFileInputStream     *stream,
  66                                                               char                 *attributes,
  67                                                               int                   io_priority,
  68                                                               GCancellable         *cancellable,
  69                                                               GAsyncReadyCallback   callback,
  70                                                               gpointer              user_data);
  71 static GFileInfo *g_file_input_stream_real_query_info_finish (GFileInputStream     *stream,
  72                                                               GAsyncResult         *result,
  73                                                               GError              **error);
  74
  75
  76 G_DEFINE_TYPE_WITH_CODE (GFileInputStream, g_file_input_stream, G_TYPE_INPUT_STREAM,
  77                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  78                                                 g_file_input_stream_seekable_iface_init))
  79
  80 struct _GFileInputStreamPrivate {
  81   GAsyncReadyCallback outstanding_callback;
  82 };
  83
  84 static void
  85 g_file_input_stream_class_init (GFileInputStreamClass *klass)
  86 {
  87   g_type_class_add_private (klass, sizeof (GFileInputStreamPrivate));
  88
  89   klass->query_info_async = g_file_input_stream_real_query_info_async;
  90   klass->query_info_finish = g_file_input_stream_real_query_info_finish;
  91 }
  92
  93 static void
  94 g_file_input_stream_seekable_iface_init (GSeekableIface *iface)
  95 {
  96   iface->tell = g_file_input_stream_seekable_tell;
  97   iface->can_seek = g_file_input_stream_seekable_can_seek;
  98   iface->seek = g_file_input_stream_seekable_seek;
  99   iface->can_truncate = g_file_input_stream_seekable_can_truncate;
 100   iface->truncate_fn = g_file_input_stream_seekable_truncate;
 101 }
 102
 103 static void
 104 g_file_input_stream_init (GFileInputStream *stream)
 105 {
 106   stream->priv = G_TYPE_INSTANCE_GET_PRIVATE (stream,
 107                                               G_TYPE_FILE_INPUT_STREAM,
 108                                               GFileInputStreamPrivate);
 109 }
 110
 111 /**
 112  * g_file_input_stream_query_info:
 113  * @stream: a #GFileInputStream.
 114  * @attributes: a file attribute query string.
 115  * @cancellable: optional #GCancellable object, %NULL to ignore.
 116  * @error: a #GError location to store the error occuring, or %NULL to
 117  * ignore.
 118  *
 119  * Queries a file input stream the given @attributes.his function blocks
 120  * while querying the stream. For the asynchronous (non-blocking) version
 121  * of this function, see g_file_input_stream_query_info_async(). While the
 122  * stream is blocked, the stream will set the pending flag internally, and
 123  * any other operations on the stream will fail with %G_IO_ERROR_PENDING.
 124  *
 125  * Returns: a #GFileInfo, or %NULL on error.
 126  **/
 127 GFileInfo *
 128 g_file_input_stream_query_info (GFileInputStream  *stream,
 129                                 char              *attributes,
 130                                 GCancellable      *cancellable,
 131                                 GError           **error)
 132 {
 133   GFileInputStreamClass *class;
 134   GInputStream *input_stream;
 135   GFileInfo *info;
 136
 137   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
 138
 139   input_stream = G_INPUT_STREAM (stream);
 140
 141   if (!g_input_stream_set_pending (input_stream, error))
 142     return NULL;
 143
 144   info = NULL;
 145
 146   if (cancellable)
 147     g_cancellable_push_current (cancellable);
 148
 149   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 150   if (class->query_info)
 151     info = class->query_info (stream, attributes, cancellable, error);
 152   else
 153     g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 154                  _("Stream doesn't support query_info"));
 155
 156   if (cancellable)
 157     g_cancellable_pop_current (cancellable);
 158
 159   g_input_stream_clear_pending (input_stream);
 160
 161   return info;
 162 }
 163
 164 static void
 165 async_ready_callback_wrapper (GObject      *source_object,
 166                               GAsyncResult *res,
 167                               gpointer      user_data)
 168 {
 169   GFileInputStream *stream = G_FILE_INPUT_STREAM (source_object);
 170
 171   g_input_stream_clear_pending (G_INPUT_STREAM (stream));
 172   if (stream->priv->outstanding_callback)
 173     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 174   g_object_unref (stream);
 175 }
 176
 177 /**
 178  * g_file_input_stream_query_info_async:
 179  * @stream: a #GFileInputStream.
 180  * @attributes: a file attribute query string.
 181  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 182  *     of the request.
 183  * @cancellable: optional #GCancellable object, %NULL to ignore.
 184  * @callback: callback to call when the request is satisfied
 185  * @user_data: the data to pass to callback function
 186  *
 187  * Queries the stream information asynchronously. For the synchronous
 188  * version of this function, see g_file_input_stream_query_info().
 189  *
 190  * If @cancellable is not %NULL, then the operation can be cancelled by
 191  * triggering the cancellable object from another thread. If the operation
 192  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set
 193  *
 194  **/
 195 void
 196 g_file_input_stream_query_info_async (GFileInputStream    *stream,
 197                                       char                *attributes,
 198                                       int                  io_priority,
 199                                       GCancellable        *cancellable,
 200                                       GAsyncReadyCallback  callback,
 201                                       gpointer             user_data)
 202 {
 203   GFileInputStreamClass *klass;
 204   GInputStream *input_stream;
 205   GError *error = NULL;
 206
 207   g_return_if_fail (G_IS_FILE_INPUT_STREAM (stream));
 208
 209   input_stream = G_INPUT_STREAM (stream);
 210
 211   if (!g_input_stream_set_pending (input_stream, &error))
 212     {
 213       g_simple_async_report_gerror_in_idle (G_OBJECT (stream),
 214                                             callback,
 215                                             user_data,
 216                                             error);
 217       g_error_free (error);
 218       return;
 219     }
 220
 221   klass = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 222
 223   stream->priv->outstanding_callback = callback;
 224   g_object_ref (stream);
 225   klass->query_info_async (stream, attributes, io_priority, cancellable,
 226                               async_ready_callback_wrapper, user_data);
 227 }
 228
 229 /**
 230  * g_file_input_stream_query_info_finish:
 231  * @stream: a #GFileInputStream.
 232  * @result: a #GAsyncResult.
 233  * @error: a #GError location to store the error occuring,
 234  *     or %NULL to ignore.
 235  *
 236  * Finishes an asynchronous info query operation.
 237  *
 238  * Returns: #GFileInfo.
 239  **/
 240 GFileInfo *
 241 g_file_input_stream_query_info_finish (GFileInputStream  *stream,
 242                                        GAsyncResult      *result,
 243                                        GError           **error)
 244 {
 245   GSimpleAsyncResult *simple;
 246   GFileInputStreamClass *class;
 247
 248   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
 249   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 250
 251   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 252     {
 253       simple = G_SIMPLE_ASYNC_RESULT (result);
 254       if (g_simple_async_result_propagate_error (simple, error))
 255         return NULL;
 256     }
 257
 258   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 259   return class->query_info_finish (stream, result, error);
 260 }
 261
 262 /**
 263  * g_file_input_stream_tell:
 264  * @stream: a #GFileInputStream.
 265  *
 266  * Gets the current position in the stream.
 267  *
 268  * Returns: a #goffset with the position in the stream.
 269  **/
 270 goffset
 271 g_file_input_stream_tell (GFileInputStream *stream)
 272 {
 273   GFileInputStreamClass *class;
 274   goffset offset;
 275
 276   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), 0);
 277
 278   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 279
 280   offset = 0;
 281   if (class->tell)
 282     offset = class->tell (stream);
 283
 284   return offset;
 285 }
 286
 287 static goffset
 288 g_file_input_stream_seekable_tell (GSeekable *seekable)
 289 {
 290   return g_file_input_stream_tell (G_FILE_INPUT_STREAM (seekable));
 291 }
 292
 293 /**
 294  * g_file_input_stream_can_seek:
 295  * @stream: a #GFileInputStream.
 296  *
 297  * Checks if a file input stream can be seeked.
 298  *
 299  * Returns: %TRUE if stream can be seeked. %FALSE otherwise.
 300  **/
 301 gboolean
 302 g_file_input_stream_can_seek (GFileInputStream *stream)
 303 {
 304   GFileInputStreamClass *class;
 305   gboolean can_seek;
 306
 307   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 308
 309   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 310
 311   can_seek = FALSE;
 312   if (class->seek)
 313     {
 314       can_seek = TRUE;
 315       if (class->can_seek)
 316         can_seek = class->can_seek (stream);
 317     }
 318
 319   return can_seek;
 320 }
 321
 322 static gboolean
 323 g_file_input_stream_seekable_can_seek (GSeekable *seekable)
 324 {
 325   return g_file_input_stream_can_seek (G_FILE_INPUT_STREAM (seekable));
 326 }
 327
 328 /**
 329  * g_file_input_stream_seek:
 330  * @stream: a #GFileInputStream.
 331  * @offset: a #goffset to seek.
 332  * @type: a #GSeekType.
 333  * @cancellable: optional #GCancellable object, %NULL to ignore.
 334  * @error: a #GError location to store the error occuring, or
 335  *     %NULL to ignore.
 336  *
 337  * Seeks in the file input stream.
 338  *
 339  * If @cancellable is not %NULL, then the operation can be cancelled by
 340  * triggering the cancellable object from another thread. If the operation
 341  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set.
 342  *
 343  * Returns: %TRUE if the stream was successfully seeked to the position.
 344  * %FALSE on error.
 345  **/
 346 gboolean
 347 g_file_input_stream_seek (GFileInputStream  *stream,
 348                           goffset            offset,
 349                           GSeekType          type,
 350                           GCancellable      *cancellable,
 351                           GError           **error)
 352 {
 353   GFileInputStreamClass *class;
 354   GInputStream *input_stream;
 355   gboolean res;
 356
 357   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 358
 359   input_stream = G_INPUT_STREAM (stream);
 360   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 361
 362   if (!class->seek)
 363     {
 364       g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 365                    _("Seek not supported on stream"));
 366       return FALSE;
 367     }
 368
 369   if (!g_input_stream_set_pending (input_stream, error))
 370     return FALSE;
 371
 372   if (cancellable)
 373     g_cancellable_push_current (cancellable);
 374
 375   res = class->seek (stream, offset, type, cancellable, error);
 376
 377   if (cancellable)
 378     g_cancellable_pop_current (cancellable);
 379
 380   g_input_stream_clear_pending (input_stream);
 381
 382   return res;
 383 }
 384
 385 static gboolean
 386 g_file_input_stream_seekable_seek (GSeekable     *seekable,
 387                                    goffset        offset,
 388                                    GSeekType      type,
 389                                    GCancellable  *cancellable,
 390                                    GError       **error)
 391 {
 392   return g_file_input_stream_seek (G_FILE_INPUT_STREAM (seekable),
 393                                    offset, type, cancellable, error);
 394 }
 395
 396 static gboolean
 397 g_file_input_stream_seekable_can_truncate (GSeekable *seekable)
 398 {
 399   return FALSE;
 400 }
 401
 402 static gboolean
 403 g_file_input_stream_seekable_truncate (GSeekable     *seekable,
 404                                        goffset        offset,
 405                                        GCancellable  *cancellable,
 406                                        GError       **error)
 407 {
 408   g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 409                _("Truncate not allowed on input stream"));
 410   return FALSE;
 411 }
 412
 413 /********************************************
 414  *   Default implementation of async ops    *
 415  ********************************************/
 416
 417 typedef struct {
 418   char *attributes;
 419   GFileInfo *info;
 420 } QueryInfoAsyncData;
 421
 422 static void
 423 query_info_data_free (QueryInfoAsyncData *data)
 424 {
 425   if (data->info)
 426     g_object_unref (data->info);
 427   g_free (data->attributes);
 428   g_free (data);
 429 }
 430
 431 static void
 432 query_info_async_thread (GSimpleAsyncResult *res,
 433                          GObject            *object,
 434                          GCancellable       *cancellable)
 435 {
 436   GFileInputStreamClass *class;
 437   GError *error = NULL;
 438   QueryInfoAsyncData *data;
 439   GFileInfo *info;
 440
 441   data = g_simple_async_result_get_op_res_gpointer (res);
 442
 443   info = NULL;
 444
 445   class = G_FILE_INPUT_STREAM_GET_CLASS (object);
 446   if (class->query_info)
 447     info = class->query_info (G_FILE_INPUT_STREAM (object), data->attributes, cancellable, &error);
 448   else
 449     g_set_error (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 450                  _("Stream doesn't support query_info"));
 451
 452   if (info == NULL)
 453     {
 454       g_simple_async_result_set_from_error (res, error);
 455       g_error_free (error);
 456     }
 457   else
 458     data->info = info;
 459 }
 460
 461 static void
 462 g_file_input_stream_real_query_info_async (GFileInputStream    *stream,
 463                                            char                *attributes,
 464                                            int                  io_priority,
 465                                            GCancellable        *cancellable,
 466                                            GAsyncReadyCallback  callback,
 467                                            gpointer             user_data)
 468 {
 469   GSimpleAsyncResult *res;
 470   QueryInfoAsyncData *data;
 471
 472   data = g_new0 (QueryInfoAsyncData, 1);
 473   data->attributes = g_strdup (attributes);
 474
 475   res = g_simple_async_result_new (G_OBJECT (stream), callback, user_data, g_file_input_stream_real_query_info_async);
 476   g_simple_async_result_set_op_res_gpointer (res, data, (GDestroyNotify)query_info_data_free);
 477
 478   g_simple_async_result_run_in_thread (res, query_info_async_thread, io_priority, cancellable);
 479   g_object_unref (res);
 480 }
 481
 482 static GFileInfo *
 483 g_file_input_stream_real_query_info_finish (GFileInputStream  *stream,
 484                                             GAsyncResult      *res,
 485                                             GError           **error)
 486 {
 487   GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
 488   QueryInfoAsyncData *data;
 489
 490   g_warn_if_fail (g_simple_async_result_get_source_tag (simple) == g_file_input_stream_real_query_info_async);
 491
 492   data = g_simple_async_result_get_op_res_gpointer (simple);
 493   if (data->info)
 494     return g_object_ref (data->info);
 495
 496   return NULL;
 497 }
 498
 499 #define __G_FILE_INPUT_STREAM_C__
 500 #include "gioaliasdef.c"
 501