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