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 "gcancellable.h"
  30 #include "gasyncresult.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_stream_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   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. This 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: (transfer full): a #GFileInfo, or %NULL on error.
 126  **/
 127 GFileInfo *
 128 g_file_input_stream_query_info (GFileInputStream  *stream,
 129                                 const 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_literal (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.
 188  * When the operation is finished @callback will be called.
 189  * You can then call g_file_input_stream_query_info_finish()
 190  * to get the result of the operation.
 191  *
 192  * For the synchronous version of this function,
 193  * see g_file_input_stream_query_info().
 194  *
 195  * If @cancellable is not %NULL, then the operation can be cancelled by
 196  * triggering the cancellable object from another thread. If the operation
 197  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set
 198  *
 199  **/
 200 void
 201 g_file_input_stream_query_info_async (GFileInputStream    *stream,
 202                                       const char          *attributes,
 203                                       int                  io_priority,
 204                                       GCancellable        *cancellable,
 205                                       GAsyncReadyCallback  callback,
 206                                       gpointer             user_data)
 207 {
 208   GFileInputStreamClass *klass;
 209   GInputStream *input_stream;
 210   GError *error = NULL;
 211
 212   g_return_if_fail (G_IS_FILE_INPUT_STREAM (stream));
 213
 214   input_stream = G_INPUT_STREAM (stream);
 215
 216   if (!g_input_stream_set_pending (input_stream, &error))
 217     {
 218       g_simple_async_report_gerror_in_idle (G_OBJECT (stream),
 219                                             callback,
 220                                             user_data,
 221                                             error);
 222       g_error_free (error);
 223       return;
 224     }
 225
 226   klass = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 227
 228   stream->priv->outstanding_callback = callback;
 229   g_object_ref (stream);
 230   klass->query_info_async (stream, attributes, io_priority, cancellable,
 231                               async_ready_callback_wrapper, user_data);
 232 }
 233
 234 /**
 235  * g_file_input_stream_query_info_finish:
 236  * @stream: a #GFileInputStream.
 237  * @result: a #GAsyncResult.
 238  * @error: a #GError location to store the error occuring,
 239  *     or %NULL to ignore.
 240  *
 241  * Finishes an asynchronous info query operation.
 242  *
 243  * Returns: (transfer full): #GFileInfo.
 244  **/
 245 GFileInfo *
 246 g_file_input_stream_query_info_finish (GFileInputStream  *stream,
 247                                        GAsyncResult      *result,
 248                                        GError           **error)
 249 {
 250   GSimpleAsyncResult *simple;
 251   GFileInputStreamClass *class;
 252
 253   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
 254   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 255
 256   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 257     {
 258       simple = G_SIMPLE_ASYNC_RESULT (result);
 259       if (g_simple_async_result_propagate_error (simple, error))
 260         return NULL;
 261     }
 262
 263   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 264   return class->query_info_finish (stream, result, error);
 265 }
 266
 267 static goffset
 268 g_file_input_stream_tell (GFileInputStream *stream)
 269 {
 270   GFileInputStreamClass *class;
 271   goffset offset;
 272
 273   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), 0);
 274
 275   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 276
 277   offset = 0;
 278   if (class->tell)
 279     offset = class->tell (stream);
 280
 281   return offset;
 282 }
 283
 284 static goffset
 285 g_file_input_stream_seekable_tell (GSeekable *seekable)
 286 {
 287   return g_file_input_stream_tell (G_FILE_INPUT_STREAM (seekable));
 288 }
 289
 290 static gboolean
 291 g_file_input_stream_can_seek (GFileInputStream *stream)
 292 {
 293   GFileInputStreamClass *class;
 294   gboolean can_seek;
 295
 296   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 297
 298   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 299
 300   can_seek = FALSE;
 301   if (class->seek)
 302     {
 303       can_seek = TRUE;
 304       if (class->can_seek)
 305         can_seek = class->can_seek (stream);
 306     }
 307
 308   return can_seek;
 309 }
 310
 311 static gboolean
 312 g_file_input_stream_seekable_can_seek (GSeekable *seekable)
 313 {
 314   return g_file_input_stream_can_seek (G_FILE_INPUT_STREAM (seekable));
 315 }
 316
 317 static gboolean
 318 g_file_input_stream_seek (GFileInputStream  *stream,
 319                           goffset            offset,
 320                           GSeekType          type,
 321                           GCancellable      *cancellable,
 322                           GError           **error)
 323 {
 324   GFileInputStreamClass *class;
 325   GInputStream *input_stream;
 326   gboolean res;
 327
 328   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 329
 330   input_stream = G_INPUT_STREAM (stream);
 331   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 332
 333   if (!class->seek)
 334     {
 335       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 336                            _("Seek not supported on stream"));
 337       return FALSE;
 338     }
 339
 340   if (!g_input_stream_set_pending (input_stream, error))
 341     return FALSE;
 342
 343   if (cancellable)
 344     g_cancellable_push_current (cancellable);
 345
 346   res = class->seek (stream, offset, type, cancellable, error);
 347
 348   if (cancellable)
 349     g_cancellable_pop_current (cancellable);
 350
 351   g_input_stream_clear_pending (input_stream);
 352
 353   return res;
 354 }
 355
 356 static gboolean
 357 g_file_input_stream_seekable_seek (GSeekable     *seekable,
 358                                    goffset        offset,
 359                                    GSeekType      type,
 360                                    GCancellable  *cancellable,
 361                                    GError       **error)
 362 {
 363   return g_file_input_stream_seek (G_FILE_INPUT_STREAM (seekable),
 364                                    offset, type, cancellable, error);
 365 }
 366
 367 static gboolean
 368 g_file_input_stream_seekable_can_truncate (GSeekable *seekable)
 369 {
 370   return FALSE;
 371 }
 372
 373 static gboolean
 374 g_file_input_stream_seekable_truncate (GSeekable     *seekable,
 375                                        goffset        offset,
 376                                        GCancellable  *cancellable,
 377                                        GError       **error)
 378 {
 379   g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 380                        _("Truncate not allowed on input stream"));
 381   return FALSE;
 382 }
 383
 384 /********************************************
 385  *   Default implementation of async ops    *
 386  ********************************************/
 387
 388 typedef struct {
 389   char *attributes;
 390   GFileInfo *info;
 391 } QueryInfoAsyncData;
 392
 393 static void
 394 query_info_data_free (QueryInfoAsyncData *data)
 395 {
 396   if (data->info)
 397     g_object_unref (data->info);
 398   g_free (data->attributes);
 399   g_free (data);
 400 }
 401
 402 static void
 403 query_info_async_thread (GSimpleAsyncResult *res,
 404                          GObject            *object,
 405                          GCancellable       *cancellable)
 406 {
 407   GFileInputStreamClass *class;
 408   GError *error = NULL;
 409   QueryInfoAsyncData *data;
 410   GFileInfo *info;
 411
 412   data = g_simple_async_result_get_op_res_gpointer (res);
 413
 414   info = NULL;
 415
 416   class = G_FILE_INPUT_STREAM_GET_CLASS (object);
 417   if (class->query_info)
 418     info = class->query_info (G_FILE_INPUT_STREAM (object), data->attributes, cancellable, &error);
 419   else
 420     g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 421                          _("Stream doesn't support query_info"));
 422
 423   if (info == NULL)
 424     g_simple_async_result_take_error (res, error);
 425   else
 426     data->info = info;
 427 }
 428
 429 static void
 430 g_file_input_stream_real_query_info_async (GFileInputStream    *stream,
 431                                            const char          *attributes,
 432                                            int                  io_priority,
 433                                            GCancellable        *cancellable,
 434                                            GAsyncReadyCallback  callback,
 435                                            gpointer             user_data)
 436 {
 437   GSimpleAsyncResult *res;
 438   QueryInfoAsyncData *data;
 439
 440   data = g_new0 (QueryInfoAsyncData, 1);
 441   data->attributes = g_strdup (attributes);
 442
 443   res = g_simple_async_result_new (G_OBJECT (stream), callback, user_data, g_file_input_stream_real_query_info_async);
 444   g_simple_async_result_set_op_res_gpointer (res, data, (GDestroyNotify)query_info_data_free);
 445
 446   g_simple_async_result_run_in_thread (res, query_info_async_thread, io_priority, cancellable);
 447   g_object_unref (res);
 448 }
 449
 450 static GFileInfo *
 451 g_file_input_stream_real_query_info_finish (GFileInputStream  *stream,
 452                                             GAsyncResult      *res,
 453                                             GError           **error)
 454 {
 455   GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
 456   QueryInfoAsyncData *data;
 457
 458   g_warn_if_fail (g_simple_async_result_get_source_tag (simple) == g_file_input_stream_real_query_info_async);
 459
 460   data = g_simple_async_result_get_op_res_gpointer (simple);
 461   if (data->info)
 462     return g_object_ref (data->info);
 463
 464   return NULL;
 465 }