gio/gseekable.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 #include "gseekable.h"
  25 #include "glibintl.h"
  26
  27
  28 /**
  29  * SECTION:gseekable
  30  * @short_description: Stream seeking interface
  31  * @include: gio/gio.h
  32  * @see_also: #GInputStream, #GOutputStream
  33  *
  34  * #GSeekable is implemented by streams (implementations of
  35  * #GInputStream or #GOutputStream) that support seeking.
  36  *
  37  **/
  38
  39 typedef GSeekableIface GSeekableInterface;
  40 G_DEFINE_INTERFACE (GSeekable, g_seekable, G_TYPE_OBJECT)
  41
  42 static void
  43 g_seekable_default_init (GSeekableInterface *iface)
  44 {
  45 }
  46
  47 /**
  48  * g_seekable_tell:
  49  * @seekable: a #GSeekable.
  50  *
  51  * Tells the current position within the stream.
  52  *
  53  * Returns: the offset from the beginning of the buffer.
  54  **/
  55 goffset
  56 g_seekable_tell (GSeekable *seekable)
  57 {
  58   GSeekableIface *iface;
  59
  60   g_return_val_if_fail (G_IS_SEEKABLE (seekable), 0);
  61
  62   iface = G_SEEKABLE_GET_IFACE (seekable);
  63
  64   return (* iface->tell) (seekable);
  65 }
  66
  67 /**
  68  * g_seekable_can_seek:
  69  * @seekable: a #GSeekable.
  70  *
  71  * Tests if the stream supports the #GSeekableIface.
  72  *
  73  * Returns: %TRUE if @seekable can be seeked. %FALSE otherwise.
  74  **/
  75 gboolean
  76 g_seekable_can_seek (GSeekable *seekable)
  77 {
  78   GSeekableIface *iface;
  79
  80   g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
  81
  82   iface = G_SEEKABLE_GET_IFACE (seekable);
  83
  84   return (* iface->can_seek) (seekable);
  85 }
  86
  87 /**
  88  * g_seekable_seek:
  89  * @seekable: a #GSeekable.
  90  * @offset: a #goffset.
  91  * @type: a #GSeekType.
  92  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
  93  * @error: a #GError location to store the error occurring, or %NULL to
  94  * ignore.
  95  *
  96  * Seeks in the stream by the given @offset, modified by @type.
  97  *
  98  * If @cancellable is not %NULL, then the operation can be cancelled by
  99  * triggering the cancellable object from another thread. If the operation
 100  * was cancelled, the error %G_IO_ERROR_CANCELLED will be returned.
 101  *
 102  * Returns: %TRUE if successful. If an error
 103  *     has occurred, this function will return %FALSE and set @error
 104  *     appropriately if present.
 105  **/
 106 gboolean
 107 g_seekable_seek (GSeekable     *seekable,
 108                  goffset        offset,
 109                  GSeekType      type,
 110                  GCancellable  *cancellable,
 111                  GError       **error)
 112 {
 113   GSeekableIface *iface;
 114
 115   g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
 116
 117   iface = G_SEEKABLE_GET_IFACE (seekable);
 118
 119   return (* iface->seek) (seekable, offset, type, cancellable, error);
 120 }
 121
 122 /**
 123  * g_seekable_can_truncate:
 124  * @seekable: a #GSeekable.
 125  *
 126  * Tests if the stream can be truncated.
 127  *
 128  * Returns: %TRUE if the stream can be truncated, %FALSE otherwise.
 129  **/
 130 gboolean
 131 g_seekable_can_truncate (GSeekable *seekable)
 132 {
 133   GSeekableIface *iface;
 134
 135   g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
 136
 137   iface = G_SEEKABLE_GET_IFACE (seekable);
 138
 139   return (* iface->can_truncate) (seekable);
 140 }
 141
 142 /**
 143  * g_seekable_truncate:
 144  * @seekable: a #GSeekable.
 145  * @offset: a #goffset.
 146  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 147  * @error: a #GError location to store the error occurring, or %NULL to
 148  * ignore.
 149  *
 150  * Truncates a stream with a given #offset.
 151  *
 152  * If @cancellable is not %NULL, then the operation can be cancelled by
 153  * triggering the cancellable object from another thread. If the operation
 154  * was cancelled, the error %G_IO_ERROR_CANCELLED will be returned. If an
 155  * operation was partially finished when the operation was cancelled the
 156  * partial result will be returned, without an error.
 157  *
 158  * Virtual: truncate_fn
 159  * Returns: %TRUE if successful. If an error
 160  *     has occurred, this function will return %FALSE and set @error
 161  *     appropriately if present.
 162  **/
 163 gboolean
 164 g_seekable_truncate (GSeekable     *seekable,
 165                      goffset        offset,
 166                      GCancellable  *cancellable,
 167                      GError       **error)
 168 {
 169   GSeekableIface *iface;
 170
 171   g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
 172
 173   iface = G_SEEKABLE_GET_IFACE (seekable);
 174
 175   return (* iface->truncate_fn) (seekable, offset, cancellable, error);
 176 }