gio/gfileinputstream.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright (C) 2006-2007 Red Hat, Inc.
   4  *
   5  * SPDX-License-Identifier: LGPL-2.1-or-later
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General
  18  * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
  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 struct _GFileInputStreamPrivate {
  77   GAsyncReadyCallback outstanding_callback;
  78 };
  79
  80 G_DEFINE_TYPE_WITH_CODE (GFileInputStream, g_file_input_stream, G_TYPE_INPUT_STREAM,
  81                          G_ADD_PRIVATE (GFileInputStream)
  82                          G_IMPLEMENT_INTERFACE (G_TYPE_SEEKABLE,
  83                                                 g_file_input_stream_seekable_iface_init))
  84
  85 static void
  86 g_file_input_stream_class_init (GFileInputStreamClass *klass)
  87 {
  88   klass->query_info_async = g_file_input_stream_real_query_info_async;
  89   klass->query_info_finish = g_file_input_stream_real_query_info_finish;
  90 }
  91
  92 static void
  93 g_file_input_stream_seekable_iface_init (GSeekableIface *iface)
  94 {
  95   iface->tell = g_file_input_stream_seekable_tell;
  96   iface->can_seek = g_file_input_stream_seekable_can_seek;
  97   iface->seek = g_file_input_stream_seekable_seek;
  98   iface->can_truncate = g_file_input_stream_seekable_can_truncate;
  99   iface->truncate_fn = g_file_input_stream_seekable_truncate;
 100 }
 101
 102 static void
 103 g_file_input_stream_init (GFileInputStream *stream)
 104 {
 105   stream->priv = g_file_input_stream_get_instance_private (stream);
 106 }
 107
 108 /**
 109  * g_file_input_stream_query_info:
 110  * @stream: a #GFileInputStream.
 111  * @attributes: a file attribute query string.
 112  * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
 113  * @error: a #GError location to store the error occurring, or %NULL to
 114  * ignore.
 115  *
 116  * Queries a file input stream the given @attributes. This function blocks
 117  * while querying the stream. For the asynchronous (non-blocking) version
 118  * of this function, see g_file_input_stream_query_info_async(). While the
 119  * stream is blocked, the stream will set the pending flag internally, and
 120  * any other operations on the stream will fail with %G_IO_ERROR_PENDING.
 121  *
 122  * Returns: (transfer full): a #GFileInfo, or %NULL on error.
 123  **/
 124 GFileInfo *
 125 g_file_input_stream_query_info (GFileInputStream  *stream,
 126                                 const char        *attributes,
 127                                 GCancellable      *cancellable,
 128                                 GError           **error)
 129 {
 130   GFileInputStreamClass *class;
 131   GInputStream *input_stream;
 132   GFileInfo *info;
 133
 134   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
 135
 136   input_stream = G_INPUT_STREAM (stream);
 137
 138   if (!g_input_stream_set_pending (input_stream, error))
 139     return NULL;
 140
 141   info = NULL;
 142
 143   if (cancellable)
 144     g_cancellable_push_current (cancellable);
 145
 146   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 147   if (class->query_info)
 148     info = class->query_info (stream, attributes, cancellable, error);
 149   else
 150     g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 151                          _("Stream doesn’t support query_info"));
 152
 153   if (cancellable)
 154     g_cancellable_pop_current (cancellable);
 155
 156   g_input_stream_clear_pending (input_stream);
 157
 158   return info;
 159 }
 160
 161 static void
 162 async_ready_callback_wrapper (GObject      *source_object,
 163                               GAsyncResult *res,
 164                               gpointer      user_data)
 165 {
 166   GFileInputStream *stream = G_FILE_INPUT_STREAM (source_object);
 167
 168   g_input_stream_clear_pending (G_INPUT_STREAM (stream));
 169   if (stream->priv->outstanding_callback)
 170     (*stream->priv->outstanding_callback) (source_object, res, user_data);
 171   g_object_unref (stream);
 172 }
 173
 174 /**
 175  * g_file_input_stream_query_info_async:
 176  * @stream: a #GFileInputStream.
 177  * @attributes: a file attribute query string.
 178  * @io_priority: the [I/O priority][io-priority] of the request
 179  * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
 180  * @callback: (scope async): a #GAsyncReadyCallback
 181  *   to call when the request is satisfied
 182  * @user_data: the data to pass to callback function
 183  *
 184  * Queries the stream information asynchronously.
 185  * When the operation is finished @callback will be called.
 186  * You can then call g_file_input_stream_query_info_finish()
 187  * to get the result of the operation.
 188  *
 189  * For the synchronous version of this function,
 190  * see g_file_input_stream_query_info().
 191  *
 192  * If @cancellable is not %NULL, then the operation can be cancelled by
 193  * triggering the cancellable object from another thread. If the operation
 194  * was cancelled, the error %G_IO_ERROR_CANCELLED will be set
 195  *
 196  **/
 197 void
 198 g_file_input_stream_query_info_async (GFileInputStream    *stream,
 199                                       const char          *attributes,
 200                                       int                  io_priority,
 201                                       GCancellable        *cancellable,
 202                                       GAsyncReadyCallback  callback,
 203                                       gpointer             user_data)
 204 {
 205   GFileInputStreamClass *klass;
 206   GInputStream *input_stream;
 207   GError *error = NULL;
 208
 209   g_return_if_fail (G_IS_FILE_INPUT_STREAM (stream));
 210
 211   input_stream = G_INPUT_STREAM (stream);
 212
 213   if (!g_input_stream_set_pending (input_stream, &error))
 214     {
 215       g_task_report_error (stream, callback, user_data,
 216                            g_file_input_stream_query_info_async,
 217                            error);
 218       return;
 219     }
 220
 221   klass = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 222
 223   stream->priv->outstanding_callback = callback;
 224   g_object_ref (stream);
 225   klass->query_info_async (stream, attributes, io_priority, cancellable,
 226                            async_ready_callback_wrapper, user_data);
 227 }
 228
 229 /**
 230  * g_file_input_stream_query_info_finish:
 231  * @stream: a #GFileInputStream.
 232  * @result: a #GAsyncResult.
 233  * @error: a #GError location to store the error occurring,
 234  *     or %NULL to ignore.
 235  *
 236  * Finishes an asynchronous info query operation.
 237  *
 238  * Returns: (transfer full): #GFileInfo.
 239  **/
 240 GFileInfo *
 241 g_file_input_stream_query_info_finish (GFileInputStream  *stream,
 242                                        GAsyncResult      *result,
 243                                        GError           **error)
 244 {
 245   GFileInputStreamClass *class;
 246
 247   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), NULL);
 248   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
 249
 250   if (g_async_result_legacy_propagate_error (result, error))
 251     return NULL;
 252   else if (g_async_result_is_tagged (result, g_file_input_stream_query_info_async))
 253     return g_task_propagate_pointer (G_TASK (result), error);
 254
 255   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 256   return class->query_info_finish (stream, result, error);
 257 }
 258
 259 static goffset
 260 g_file_input_stream_tell (GFileInputStream *stream)
 261 {
 262   GFileInputStreamClass *class;
 263   goffset offset;
 264
 265   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), 0);
 266
 267   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 268
 269   offset = 0;
 270   if (class->tell)
 271     offset = class->tell (stream);
 272
 273   return offset;
 274 }
 275
 276 static goffset
 277 g_file_input_stream_seekable_tell (GSeekable *seekable)
 278 {
 279   return g_file_input_stream_tell (G_FILE_INPUT_STREAM (seekable));
 280 }
 281
 282 static gboolean
 283 g_file_input_stream_can_seek (GFileInputStream *stream)
 284 {
 285   GFileInputStreamClass *class;
 286   gboolean can_seek;
 287
 288   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 289
 290   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 291
 292   can_seek = FALSE;
 293   if (class->seek)
 294     {
 295       can_seek = TRUE;
 296       if (class->can_seek)
 297         can_seek = class->can_seek (stream);
 298     }
 299
 300   return can_seek;
 301 }
 302
 303 static gboolean
 304 g_file_input_stream_seekable_can_seek (GSeekable *seekable)
 305 {
 306   return g_file_input_stream_can_seek (G_FILE_INPUT_STREAM (seekable));
 307 }
 308
 309 static gboolean
 310 g_file_input_stream_seek (GFileInputStream  *stream,
 311                           goffset            offset,
 312                           GSeekType          type,
 313                           GCancellable      *cancellable,
 314                           GError           **error)
 315 {
 316   GFileInputStreamClass *class;
 317   GInputStream *input_stream;
 318   gboolean res;
 319
 320   g_return_val_if_fail (G_IS_FILE_INPUT_STREAM (stream), FALSE);
 321
 322   input_stream = G_INPUT_STREAM (stream);
 323   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 324
 325   if (!class->seek)
 326     {
 327       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 328                            _("Seek not supported on stream"));
 329       return FALSE;
 330     }
 331
 332   if (!g_input_stream_set_pending (input_stream, error))
 333     return FALSE;
 334
 335   if (cancellable)
 336     g_cancellable_push_current (cancellable);
 337
 338   res = class->seek (stream, offset, type, cancellable, error);
 339
 340   if (cancellable)
 341     g_cancellable_pop_current (cancellable);
 342
 343   g_input_stream_clear_pending (input_stream);
 344
 345   return res;
 346 }
 347
 348 static gboolean
 349 g_file_input_stream_seekable_seek (GSeekable     *seekable,
 350                                    goffset        offset,
 351                                    GSeekType      type,
 352                                    GCancellable  *cancellable,
 353                                    GError       **error)
 354 {
 355   return g_file_input_stream_seek (G_FILE_INPUT_STREAM (seekable),
 356                                    offset, type, cancellable, error);
 357 }
 358
 359 static gboolean
 360 g_file_input_stream_seekable_can_truncate (GSeekable *seekable)
 361 {
 362   return FALSE;
 363 }
 364
 365 static gboolean
 366 g_file_input_stream_seekable_truncate (GSeekable     *seekable,
 367                                        goffset        offset,
 368                                        GCancellable  *cancellable,
 369                                        GError       **error)
 370 {
 371   g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 372                        _("Truncate not allowed on input stream"));
 373   return FALSE;
 374 }
 375
 376 /********************************************
 377  *   Default implementation of async ops    *
 378  ********************************************/
 379
 380 static void
 381 query_info_async_thread (GTask        *task,
 382                          gpointer      source_object,
 383                          gpointer      task_data,
 384                          GCancellable *cancellable)
 385 {
 386   GFileInputStream *stream = source_object;
 387   const char *attributes = task_data;
 388   GFileInputStreamClass *class;
 389   GError *error = NULL;
 390   GFileInfo *info = NULL;
 391
 392   class = G_FILE_INPUT_STREAM_GET_CLASS (stream);
 393   if (class->query_info)
 394     info = class->query_info (stream, attributes, cancellable, &error);
 395   else
 396     g_set_error_literal (&error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 397                          _("Stream doesn’t support query_info"));
 398
 399   if (info == NULL)
 400     g_task_return_error (task, error);
 401   else
 402     g_task_return_pointer (task, info, g_object_unref);
 403 }
 404
 405 static void
 406 g_file_input_stream_real_query_info_async (GFileInputStream    *stream,
 407                                            const char          *attributes,
 408                                            int                  io_priority,
 409                                            GCancellable        *cancellable,
 410                                            GAsyncReadyCallback  callback,
 411                                            gpointer             user_data)
 412 {
 413   GTask *task;
 414
 415   task = g_task_new (stream, cancellable, callback, user_data);
 416   g_task_set_source_tag (task, g_file_input_stream_real_query_info_async);
 417   g_task_set_task_data (task, g_strdup (attributes), g_free);
 418   g_task_set_priority (task, io_priority);
 419
 420   g_task_run_in_thread (task, query_info_async_thread);
 421   g_object_unref (task);
 422 }
 423
 424 static GFileInfo *
 425 g_file_input_stream_real_query_info_finish (GFileInputStream  *stream,
 426                                             GAsyncResult      *res,
 427                                             GError           **error)
 428 {
 429   g_return_val_if_fail (g_task_is_valid (res, stream), NULL);
 430
 431   return g_task_propagate_pointer (G_TASK (res), error);
 432 }