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 "gcancellable.h"
  29 #include "gasyncresult.h"
  30 #include "gtask.h"
  31 #include "gioerror.h"
  32 #include "glibintl.h"
  33
  34
  35 /**
  36  * SECTION:gfileinputstream
  37  * @short_description: File input streaming operations
  38  * @include: gio/gio.h
  39  * @see_also: #GInputStream, #GDataInputStream, #GSeekable
  40  *
  41  * GFileInputStream provides input streams that take their
  42  * content from a file.
  43  *
  44  * GFileInputStream implements #GSeekable, which allows the input
  45  * stream to jump to arbitrary positions in the file, provided the
  46  * filesystem of the file allows it. To find the position of a file
  47  * input stream, use g_seekable_tell(). To find out if a file input
  48  * stream supports seeking, use g_seekable_can_seek().
  49  * To position a file input stream, use g_seekable_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                                                               const 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   klass->query_info_async = g_file_input_stream_real_query_info_async;
  88   klass->query_info_finish = g_file_input_stream_real_query_info_finish;
  89 }
  90
  91 static void
  92 g_file_input_stream_seekable_iface_init (GSeekableIface *iface)
  93 {
  94   iface->tell = g_file_input_stream_seekable_tell;
  95   iface->can_seek = g_file_input_stream_seekable_can_seek;
  96   iface->seek = g_file_input_stream_seekable_seek;
  97   iface->can_truncate = g_file_input_stream_seekable_can_truncate;
  98   iface->truncate_fn = g_file_input_stream_seekable_truncate;
  99 }
 100
 101 static void
 102 g_file_input_stream_init (GFileInputStream *stream)
 103 {
 104   stream->priv = g_file_input_stream_get_private (stream);
 105 }
 106
 107 /**
 108  * g_file_input_stream_query_info:
 109  * @stream: a #GFileInputStream.
 110  * @attributes: a file attribute query string.
 111  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 112  * @error: a #GError location to store the error occurring, or %NULL to
 113  * ignore.
 114  *
 115  * Queries a file input stream the given @attributes. This function blocks
 116  * while querying the stream. For the asynchronous (non-blocking) version
 117  * of this function, see g_file_input_stream_query_info_async(). While the
 118  * stream is blocked, the stream will set the pending flag internally, and
 119  * any other operations on the stream will fail with %G_IO_ERROR_PENDING.
 120  *
 121  * Returns: (transfer full): a #GFileInfo, or %NULL on error.
 122  **/
 123 GFileInfo *
 124 g_file_input_stream_query_info (GFileInputStream  *stream,
 125                                 const char        *attributes,
 126                                 GCancellable      *cancellable,
 127                                 GError           **error)
 128 {
 129   GFileInputStreamClass *class;
 130   GInputStream *input_stream;
 131   GFileInfo *info;
 132
 133   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
 134
 135   input_stream = G_INPUT_STREAM (stream);
 136
 137   if (!g_input_stream_set_pending (input_stream, error))
 138     return NULL;
 139
 140   info = NULL;
 141
 142   if (cancellable)
 143     g_cancellable_push_current (cancellable);
 144
 145   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 146   if (class->query_info)
 147     info = class->query_info (stream, attributes, cancellable, error);
 148   else
 149     g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 150                          _("Stream doesn't support query_info"));
 151
 152   if (cancellable)
 153     g_cancellable_pop_current (cancellable);
 154
 155   g_input_stream_clear_pending (input_stream);
 156
 157   return info;
 158 }
 159
 160 static void
 161 async_ready_callback_wrapper (GObject      *source_object,
 162                               GAsyncResult *res,
 163                               gpointer      user_data)
 164 {
 165   GFileInputStream *stream = G_FILE_INPUT_STREAM (source_object);
 166
 167   g_input_stream_clear_pending (G_INPUT_STREAM (stream));
 168   if (stream->priv->outstanding_callback)
 169     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 170   g_object_unref (stream);
 171 }
 172
 173 /**
 174  * g_file_input_stream_query_info_async:
 175  * @stream: a #GFileInputStream.
 176  * @attributes: a file attribute query string.
 177  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 178  *     of the request.
 179  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 180  * @callback: (scope async): callback to call when the request is satisfied
 181  * @user_data: (closure): the data to pass to callback function
 182  *
 183  * Queries the stream information asynchronously.
 184  * When the operation is finished @callback will be called.
 185  * You can then call g_file_input_stream_query_info_finish()
 186  * to get the result of the operation.
 187  *
 188  * For the synchronous version of this function,
 189  * see g_file_input_stream_query_info().
 190  *
 191  * If @cancellable is not %NULL, then the operation can be cancelled by
 192  * triggering the cancellable object from another thread. If the operation
 193  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set
 194  *
 195  **/
 196 void
 197 g_file_input_stream_query_info_async (GFileInputStream    *stream,
 198                                       const char          *attributes,
 199                                       int                  io_priority,
 200                                       GCancellable        *cancellable,
 201                                       GAsyncReadyCallback  callback,
 202                                       gpointer             user_data)
 203 {
 204   GFileInputStreamClass *klass;
 205   GInputStream *input_stream;
 206   GError *error = NULL;
 207
 208   g_return_if_fail (G_IS_FILE_INPUT_STREAM (stream));
 209
 210   input_stream = G_INPUT_STREAM (stream);
 211
 212   if (!g_input_stream_set_pending (input_stream, &error))
 213     {
 214       g_task_report_error (stream, callback, user_data,
 215                            g_file_input_stream_query_info_async,
 216                            error);
 217       return;
 218     }
 219
 220   klass = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 221
 222   stream->priv->outstanding_callback = callback;
 223   g_object_ref (stream);
 224   klass->query_info_async (stream, attributes, io_priority, cancellable,
 225                            async_ready_callback_wrapper, user_data);
 226 }
 227
 228 /**
 229  * g_file_input_stream_query_info_finish:
 230  * @stream: a #GFileInputStream.
 231  * @result: a #GAsyncResult.
 232  * @error: a #GError location to store the error occurring,
 233  *     or %NULL to ignore.
 234  *
 235  * Finishes an asynchronous info query operation.
 236  *
 237  * Returns: (transfer full): #GFileInfo.
 238  **/
 239 GFileInfo *
 240 g_file_input_stream_query_info_finish (GFileInputStream  *stream,
 241                                        GAsyncResult      *result,
 242                                        GError           **error)
 243 {
 244   GFileInputStreamClass *class;
 245
 246   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
 247   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 248
 249   if (g_async_result_legacy_propagate_error (result, error))
 250     return NULL;
 251   else if (g_async_result_is_tagged (result, g_file_input_stream_query_info_async))
 252     return g_task_propagate_pointer (G_TASK (result), error);
 253
 254   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 255   return class->query_info_finish (stream, result, error);
 256 }
 257
 258 static goffset
 259 g_file_input_stream_tell (GFileInputStream *stream)
 260 {
 261   GFileInputStreamClass *class;
 262   goffset offset;
 263
 264   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), 0);
 265
 266   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 267
 268   offset = 0;
 269   if (class->tell)
 270     offset = class->tell (stream);
 271
 272   return offset;
 273 }
 274
 275 static goffset
 276 g_file_input_stream_seekable_tell (GSeekable *seekable)
 277 {
 278   return g_file_input_stream_tell (G_FILE_INPUT_STREAM (seekable));
 279 }
 280
 281 static gboolean
 282 g_file_input_stream_can_seek (GFileInputStream *stream)
 283 {
 284   GFileInputStreamClass *class;
 285   gboolean can_seek;
 286
 287   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 288
 289   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 290
 291   can_seek = FALSE;
 292   if (class->seek)
 293     {
 294       can_seek = TRUE;
 295       if (class->can_seek)
 296         can_seek = class->can_seek (stream);
 297     }
 298
 299   return can_seek;
 300 }
 301
 302 static gboolean
 303 g_file_input_stream_seekable_can_seek (GSeekable *seekable)
 304 {
 305   return g_file_input_stream_can_seek (G_FILE_INPUT_STREAM (seekable));
 306 }
 307
 308 static gboolean
 309 g_file_input_stream_seek (GFileInputStream  *stream,
 310                           goffset            offset,
 311                           GSeekType          type,
 312                           GCancellable      *cancellable,
 313                           GError           **error)
 314 {
 315   GFileInputStreamClass *class;
 316   GInputStream *input_stream;
 317   gboolean res;
 318
 319   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 320
 321   input_stream = G_INPUT_STREAM (stream);
 322   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 323
 324   if (!class->seek)
 325     {
 326       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 327                            _("Seek not supported on stream"));
 328       return FALSE;
 329     }
 330
 331   if (!g_input_stream_set_pending (input_stream, error))
 332     return FALSE;
 333
 334   if (cancellable)
 335     g_cancellable_push_current (cancellable);
 336
 337   res = class->seek (stream, offset, type, cancellable, error);
 338
 339   if (cancellable)
 340     g_cancellable_pop_current (cancellable);
 341
 342   g_input_stream_clear_pending (input_stream);
 343
 344   return res;
 345 }
 346
 347 static gboolean
 348 g_file_input_stream_seekable_seek (GSeekable     *seekable,
 349                                    goffset        offset,
 350                                    GSeekType      type,
 351                                    GCancellable  *cancellable,
 352                                    GError       **error)
 353 {
 354   return g_file_input_stream_seek (G_FILE_INPUT_STREAM (seekable),
 355                                    offset, type, cancellable, error);
 356 }
 357
 358 static gboolean
 359 g_file_input_stream_seekable_can_truncate (GSeekable *seekable)
 360 {
 361   return FALSE;
 362 }
 363
 364 static gboolean
 365 g_file_input_stream_seekable_truncate (GSeekable     *seekable,
 366                                        goffset        offset,
 367                                        GCancellable  *cancellable,
 368                                        GError       **error)
 369 {
 370   g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 371                        _("Truncate not allowed on input stream"));
 372   return FALSE;
 373 }
 374
 375 /********************************************
 376  *   Default implementation of async ops    *
 377  ********************************************/
 378
 379 static void
 380 query_info_async_thread (GTask        *task,
 381                          gpointer      source_object,
 382                          gpointer      task_data,
 383                          GCancellable *cancellable)
 384 {
 385   GFileInputStream *stream = source_object;
 386   const char *attributes = task_data;
 387   GFileInputStreamClass *class;
 388   GError *error = NULL;
 389   GFileInfo *info = NULL;
 390
 391   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 392   if (class->query_info)
 393     info = class->query_info (stream, attributes, cancellable, &error);
 394   else
 395     g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 396                          _("Stream doesn't support query_info"));
 397
 398   if (info == NULL)
 399     g_task_return_error (task, error);
 400   else
 401     g_task_return_pointer (task, info, g_object_unref);
 402 }
 403
 404 static void
 405 g_file_input_stream_real_query_info_async (GFileInputStream    *stream,
 406                                            const char          *attributes,
 407                                            int                  io_priority,
 408                                            GCancellable        *cancellable,
 409                                            GAsyncReadyCallback  callback,
 410                                            gpointer             user_data)
 411 {
 412   GTask *task;
 413
 414   task = g_task_new (stream, cancellable, callback, user_data);
 415   g_task_set_task_data (task, g_strdup (attributes), g_free);
 416   g_task_set_priority (task, io_priority);
 417
 418   g_task_run_in_thread (task, query_info_async_thread);
 419   g_object_unref (task);
 420 }
 421
 422 static GFileInfo *
 423 g_file_input_stream_real_query_info_finish (GFileInputStream  *stream,
 424                                             GAsyncResult      *res,
 425                                             GError           **error)
 426 {
 427   g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
 428
 429   return g_task_propagate_pointer (G_TASK (res), error);
 430 }