text: /* GIO - GLib Input, Output and Streaming Library
   * 
   * Copyright (C) 2006-2007 Red Hat, Inc.
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General
   * Public License along with this library; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
   * Boston, MA 02111-1307, USA.
   *
   * Author: Alexander Larsson <alexl@redhat.com>
   */
  
  #include "config.h"
  #include "gseekable.h"
  #include "glibintl.h"
  
  
  /**
   * SECTION:gseekable
   * @short_description: Stream seeking interface
   * @include: gio/gio.h
   * @see_also: #GInputStream, #GOutputStream
   * 
   * #GSeekable is implemented by streams (implementations of 
   * #GInputStream or #GOutputStream) that support seeking.
   * 
   **/
  
  typedef GSeekableIface GSeekableInterface;
  G_DEFINE_INTERFACE (GSeekable, g_seekable, G_TYPE_OBJECT)
  
  static void
  g_seekable_default_init (GSeekableInterface *iface)
  {
  }
  
  /**
   * g_seekable_tell:
   * @seekable: a #GSeekable.
   * 
   * Tells the current position within the stream.
   * 
   * Returns: the offset from the beginning of the buffer.
   **/
  goffset
  g_seekable_tell (GSeekable *seekable)
  {
    GSeekableIface *iface;
  
    g_return_val_if_fail (G_IS_SEEKABLE (seekable), 0);
  
    iface = G_SEEKABLE_GET_IFACE (seekable);
  
    return (* iface->tell) (seekable);
  }
  
  /**
   * g_seekable_can_seek:
   * @seekable: a #GSeekable.
   * 
   * Tests if the stream supports the #GSeekableIface.
   * 
   * Returns: %TRUE if @seekable can be seeked. %FALSE otherwise.
   **/
  gboolean
  g_seekable_can_seek (GSeekable *seekable)
  {
    GSeekableIface *iface;
    
    g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
  
    iface = G_SEEKABLE_GET_IFACE (seekable);
  
    return (* iface->can_seek) (seekable);
  }
  
  /**
   * g_seekable_seek:
   * @seekable: a #GSeekable.
   * @offset: a #goffset.
   * @type: a #GSeekType.
   * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore. 
   * @error: a #GError location to store the error occuring, or %NULL to 
   * ignore.
   * 
   * Seeks in the stream by the given @offset, modified by @type.
   *
   * If @cancellable is not %NULL, then the operation can be cancelled by
   * triggering the cancellable object from another thread. If the operation
   * was cancelled, the error %G_IO_ERROR_CANCELLED will be returned. 
   * 
   * Returns: %TRUE if successful. If an error
   *     has occurred, this function will return %FALSE and set @error
   *     appropriately if present.
   **/
  gboolean
  g_seekable_seek (GSeekable     *seekable,
  		 goffset        offset,
  		 GSeekType      type,
  		 GCancellable  *cancellable,
  		 GError       **error)
  {
    GSeekableIface *iface;
    
    g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
  
    iface = G_SEEKABLE_GET_IFACE (seekable);
  
    return (* iface->seek) (seekable, offset, type, cancellable, error);
  }
  
  /**
   * g_seekable_can_truncate:
   * @seekable: a #GSeekable.
   * 
   * Tests if the stream can be truncated.
   * 
   * Returns: %TRUE if the stream can be truncated, %FALSE otherwise.
   **/
  gboolean
  g_seekable_can_truncate (GSeekable *seekable)
  {
    GSeekableIface *iface;
    
    g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
  
    iface = G_SEEKABLE_GET_IFACE (seekable);
  
    return (* iface->can_truncate) (seekable);
  }
  
  /**
   * g_seekable_truncate:
   * @seekable: a #GSeekable.
   * @offset: a #goffset.
   * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore. 
   * @error: a #GError location to store the error occuring, or %NULL to 
   * ignore.
   * 
   * Truncates a stream with a given #offset. 
   * 
   * If @cancellable is not %NULL, then the operation can be cancelled by
   * triggering the cancellable object from another thread. If the operation
   * was cancelled, the error %G_IO_ERROR_CANCELLED will be returned. If an
   * operation was partially finished when the operation was cancelled the
   * partial result will be returned, without an error.
   *
   * Virtual: truncate_fn
   * Returns: %TRUE if successful. If an error
   *     has occurred, this function will return %FALSE and set @error
   *     appropriately if present. 
   **/
  gboolean
  g_seekable_truncate (GSeekable     *seekable,
  		     goffset        offset,
  		     GCancellable  *cancellable,
  		     GError       **error)
  {
    GSeekableIface *iface;
    
    g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
  
    iface = G_SEEKABLE_GET_IFACE (seekable);
  
    return (* iface->truncate_fn) (seekable, offset, cancellable, error);
  }
  