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, 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 <gfileinputstream.h>
  25 #include <gseekable.h>
  26 #include "gcancellable.h"
  27 #include "gasyncresult.h"
  28 #include "gtask.h"
  29 #include "gioerror.h"
  30 #include "glibintl.h"
  31
  32
  33 /**
  34  * SECTION:gfileinputstream
  35  * @short_description: File input streaming operations
  36  * @include: gio/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. To find the position of a file
  45  * input stream, use g_seekable_tell(). To find out if a file input
  46  * stream supports seeking, use g_seekable_can_seek().
  47  * To position a file input stream, use g_seekable_seek().
  48  **/
  49
  50 static void       g_file_input_stream_seekable_iface_init    (GSeekableIface       *iface);
  51 static goffset    g_file_input_stream_seekable_tell          (GSeekable            *seekable);
  52 static gboolean   g_file_input_stream_seekable_can_seek      (GSeekable            *seekable);
  53 static gboolean   g_file_input_stream_seekable_seek          (GSeekable            *seekable,
  54                                                               goffset               offset,
  55                                                               GSeekType             type,
  56                                                               GCancellable         *cancellable,
  57                                                               GError              **error);
  58 static gboolean   g_file_input_stream_seekable_can_truncate  (GSeekable            *seekable);
  59 static gboolean   g_file_input_stream_seekable_truncate      (GSeekable            *seekable,
  60                                                               goffset               offset,
  61                                                               GCancellable         *cancellable,
  62                                                               GError              **error);
  63 static void       g_file_input_stream_real_query_info_async  (GFileInputStream     *stream,
  64                                                               const char           *attributes,
  65                                                               int                   io_priority,
  66                                                               GCancellable         *cancellable,
  67                                                               GAsyncReadyCallback   callback,
  68                                                               gpointer              user_data);
  69 static GFileInfo *g_file_input_stream_real_query_info_finish (GFileInputStream     *stream,
  70                                                               GAsyncResult         *result,
  71                                                               GError              **error);
  72
  73
  74 struct _GFileInputStreamPrivate {
  75   GAsyncReadyCallback outstanding_callback;
  76 };
  77
  78 G_DEFINE_TYPE_WITH_CODE (GFileInputStream, g_file_input_stream, G_TYPE_INPUT_STREAM,
  79                          G_ADD_PRIVATE (GFileInputStream)
  80                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  81                                                 g_file_input_stream_seekable_iface_init))
  82
  83 static void
  84 g_file_input_stream_class_init (GFileInputStreamClass *klass)
  85 {
  86   klass->query_info_async = g_file_input_stream_real_query_info_async;
  87   klass->query_info_finish = g_file_input_stream_real_query_info_finish;
  88 }
  89
  90 static void
  91 g_file_input_stream_seekable_iface_init (GSeekableIface *iface)
  92 {
  93   iface->tell = g_file_input_stream_seekable_tell;
  94   iface->can_seek = g_file_input_stream_seekable_can_seek;
  95   iface->seek = g_file_input_stream_seekable_seek;
  96   iface->can_truncate = g_file_input_stream_seekable_can_truncate;
  97   iface->truncate_fn = g_file_input_stream_seekable_truncate;
  98 }
  99
 100 static void
 101 g_file_input_stream_init (GFileInputStream *stream)
 102 {
 103   stream->priv = g_file_input_stream_get_instance_private (stream);
 104 }
 105
 106 /**
 107  * g_file_input_stream_query_info:
 108  * @stream: a #GFileInputStream.
 109  * @attributes: a file attribute query string.
 110  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 111  * @error: a #GError location to store the error occurring, or %NULL to
 112  * ignore.
 113  *
 114  * Queries a file input stream the given @attributes. This function blocks
 115  * while querying the stream. For the asynchronous (non-blocking) version
 116  * of this function, see g_file_input_stream_query_info_async(). While the
 117  * stream is blocked, the stream will set the pending flag internally, and
 118  * any other operations on the stream will fail with %G_IO_ERROR_PENDING.
 119  *
 120  * Returns: (transfer full): a #GFileInfo, or %NULL on error.
 121  **/
 122 GFileInfo *
 123 g_file_input_stream_query_info (GFileInputStream  *stream,
 124                                 const char        *attributes,
 125                                 GCancellable      *cancellable,
 126                                 GError           **error)
 127 {
 128   GFileInputStreamClass *class;
 129   GInputStream *input_stream;
 130   GFileInfo *info;
 131
 132   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
 133
 134   input_stream = G_INPUT_STREAM (stream);
 135
 136   if (!g_input_stream_set_pending (input_stream, error))
 137     return NULL;
 138
 139   info = NULL;
 140
 141   if (cancellable)
 142     g_cancellable_push_current (cancellable);
 143
 144   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 145   if (class->query_info)
 146     info = class->query_info (stream, attributes, cancellable, error);
 147   else
 148     g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 149                          _("Stream doesn't support query_info"));
 150
 151   if (cancellable)
 152     g_cancellable_pop_current (cancellable);
 153
 154   g_input_stream_clear_pending (input_stream);
 155
 156   return info;
 157 }
 158
 159 static void
 160 async_ready_callback_wrapper (GObject      *source_object,
 161                               GAsyncResult *res,
 162                               gpointer      user_data)
 163 {
 164   GFileInputStream *stream = G_FILE_INPUT_STREAM (source_object);
 165
 166   g_input_stream_clear_pending (G_INPUT_STREAM (stream));
 167   if (stream->priv->outstanding_callback)
 168     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 169   g_object_unref (stream);
 170 }
 171
 172 /**
 173  * g_file_input_stream_query_info_async:
 174  * @stream: a #GFileInputStream.
 175  * @attributes: a file attribute query string.
 176  * @io_priority: the [I/O priority][io-priority] of the request
 177  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 178  * @callback: (scope async): callback to call when the request is satisfied
 179  * @user_data: (closure): the data to pass to callback function
 180  *
 181  * Queries the stream information asynchronously.
 182  * When the operation is finished @callback will be called.
 183  * You can then call g_file_input_stream_query_info_finish()
 184  * to get the result of the operation.
 185  *
 186  * For the synchronous version of this function,
 187  * see g_file_input_stream_query_info().
 188  *
 189  * If @cancellable is not %NULL, then the operation can be cancelled by
 190  * triggering the cancellable object from another thread. If the operation
 191  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set
 192  *
 193  **/
 194 void
 195 g_file_input_stream_query_info_async (GFileInputStream    *stream,
 196                                       const char          *attributes,
 197                                       int                  io_priority,
 198                                       GCancellable        *cancellable,
 199                                       GAsyncReadyCallback  callback,
 200                                       gpointer             user_data)
 201 {
 202   GFileInputStreamClass *klass;
 203   GInputStream *input_stream;
 204   GError *error = NULL;
 205
 206   g_return_if_fail (G_IS_FILE_INPUT_STREAM (stream));
 207
 208   input_stream = G_INPUT_STREAM (stream);
 209
 210   if (!g_input_stream_set_pending (input_stream, &error))
 211     {
 212       g_task_report_error (stream, callback, user_data,
 213                            g_file_input_stream_query_info_async,
 214                            error);
 215       return;
 216     }
 217
 218   klass = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 219
 220   stream->priv->outstanding_callback = callback;
 221   g_object_ref (stream);
 222   klass->query_info_async (stream, attributes, io_priority, cancellable,
 223                            async_ready_callback_wrapper, user_data);
 224 }
 225
 226 /**
 227  * g_file_input_stream_query_info_finish:
 228  * @stream: a #GFileInputStream.
 229  * @result: a #GAsyncResult.
 230  * @error: a #GError location to store the error occurring,
 231  *     or %NULL to ignore.
 232  *
 233  * Finishes an asynchronous info query operation.
 234  *
 235  * Returns: (transfer full): #GFileInfo.
 236  **/
 237 GFileInfo *
 238 g_file_input_stream_query_info_finish (GFileInputStream  *stream,
 239                                        GAsyncResult      *result,
 240                                        GError           **error)
 241 {
 242   GFileInputStreamClass *class;
 243
 244   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
 245   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 246
 247   if (g_async_result_legacy_propagate_error (result, error))
 248     return NULL;
 249   else if (g_async_result_is_tagged (result, g_file_input_stream_query_info_async))
 250     return g_task_propagate_pointer (G_TASK (result), error);
 251
 252   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 253   return class->query_info_finish (stream, result, error);
 254 }
 255
 256 static goffset
 257 g_file_input_stream_tell (GFileInputStream *stream)
 258 {
 259   GFileInputStreamClass *class;
 260   goffset offset;
 261
 262   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), 0);
 263
 264   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 265
 266   offset = 0;
 267   if (class->tell)
 268     offset = class->tell (stream);
 269
 270   return offset;
 271 }
 272
 273 static goffset
 274 g_file_input_stream_seekable_tell (GSeekable *seekable)
 275 {
 276   return g_file_input_stream_tell (G_FILE_INPUT_STREAM (seekable));
 277 }
 278
 279 static gboolean
 280 g_file_input_stream_can_seek (GFileInputStream *stream)
 281 {
 282   GFileInputStreamClass *class;
 283   gboolean can_seek;
 284
 285   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 286
 287   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 288
 289   can_seek = FALSE;
 290   if (class->seek)
 291     {
 292       can_seek = TRUE;
 293       if (class->can_seek)
 294         can_seek = class->can_seek (stream);
 295     }
 296
 297   return can_seek;
 298 }
 299
 300 static gboolean
 301 g_file_input_stream_seekable_can_seek (GSeekable *seekable)
 302 {
 303   return g_file_input_stream_can_seek (G_FILE_INPUT_STREAM (seekable));
 304 }
 305
 306 static gboolean
 307 g_file_input_stream_seek (GFileInputStream  *stream,
 308                           goffset            offset,
 309                           GSeekType          type,
 310                           GCancellable      *cancellable,
 311                           GError           **error)
 312 {
 313   GFileInputStreamClass *class;
 314   GInputStream *input_stream;
 315   gboolean res;
 316
 317   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 318
 319   input_stream = G_INPUT_STREAM (stream);
 320   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 321
 322   if (!class->seek)
 323     {
 324       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 325                            _("Seek not supported on stream"));
 326       return FALSE;
 327     }
 328
 329   if (!g_input_stream_set_pending (input_stream, error))
 330     return FALSE;
 331
 332   if (cancellable)
 333     g_cancellable_push_current (cancellable);
 334
 335   res = class->seek (stream, offset, type, cancellable, error);
 336
 337   if (cancellable)
 338     g_cancellable_pop_current (cancellable);
 339
 340   g_input_stream_clear_pending (input_stream);
 341
 342   return res;
 343 }
 344
 345 static gboolean
 346 g_file_input_stream_seekable_seek (GSeekable     *seekable,
 347                                    goffset        offset,
 348                                    GSeekType      type,
 349                                    GCancellable  *cancellable,
 350                                    GError       **error)
 351 {
 352   return g_file_input_stream_seek (G_FILE_INPUT_STREAM (seekable),
 353                                    offset, type, cancellable, error);
 354 }
 355
 356 static gboolean
 357 g_file_input_stream_seekable_can_truncate (GSeekable *seekable)
 358 {
 359   return FALSE;
 360 }
 361
 362 static gboolean
 363 g_file_input_stream_seekable_truncate (GSeekable     *seekable,
 364                                        goffset        offset,
 365                                        GCancellable  *cancellable,
 366                                        GError       **error)
 367 {
 368   g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 369                        _("Truncate not allowed on input stream"));
 370   return FALSE;
 371 }
 372
 373 /********************************************
 374  *   Default implementation of async ops    *
 375  ********************************************/
 376
 377 static void
 378 query_info_async_thread (GTask        *task,
 379                          gpointer      source_object,
 380                          gpointer      task_data,
 381                          GCancellable *cancellable)
 382 {
 383   GFileInputStream *stream = source_object;
 384   const char *attributes = task_data;
 385   GFileInputStreamClass *class;
 386   GError *error = NULL;
 387   GFileInfo *info = NULL;
 388
 389   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 390   if (class->query_info)
 391     info = class->query_info (stream, attributes, cancellable, &error);
 392   else
 393     g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 394                          _("Stream doesn't support query_info"));
 395
 396   if (info == NULL)
 397     g_task_return_error (task, error);
 398   else
 399     g_task_return_pointer (task, info, g_object_unref);
 400 }
 401
 402 static void
 403 g_file_input_stream_real_query_info_async (GFileInputStream    *stream,
 404                                            const char          *attributes,
 405                                            int                  io_priority,
 406                                            GCancellable        *cancellable,
 407                                            GAsyncReadyCallback  callback,
 408                                            gpointer             user_data)
 409 {
 410   GTask *task;
 411
 412   task = g_task_new (stream, cancellable, callback, user_data);
 413   g_task_set_task_data (task, g_strdup (attributes), g_free);
 414   g_task_set_priority (task, io_priority);
 415
 416   g_task_run_in_thread (task, query_info_async_thread);
 417   g_object_unref (task);
 418 }
 419
 420 static GFileInfo *
 421 g_file_input_stream_real_query_info_finish (GFileInputStream  *stream,
 422                                             GAsyncResult      *res,
 423                                             GError           **error)
 424 {
 425   g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
 426
 427   return g_task_propagate_pointer (G_TASK (res), error);
 428 }