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