/src/pango/subprojects/glib/gio/gseekable.c

Source (jump to first uncovered line)
/* GIO - GLib Input, Output and Streaming Library
 * 
 * Copyright (C) 2006-2007 Red Hat, Inc.
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 *
 * 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 2.1 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, see <http://www.gnu.org/licenses/>.
 *
 * Author: Alexander Larsson <alexl@redhat.com>
 */

#include "config.h"
#include "gseekable.h"
#include "glibintl.h"


/**
 * GSeekable:
 *
 * `GSeekable` is implemented by streams (implementations of
 * [class@Gio.InputStream] or [class@Gio.OutputStream]) that support seeking.
 *
 * Seekable streams largely fall into two categories: resizable and
 * fixed-size.
 *
 * `GSeekable` on fixed-sized streams is approximately the same as POSIX
 * [`lseek()`](man:lseek(2)) on a block device (for example: attempting to seek
 * past the end of the device is an error).  Fixed streams typically cannot be
 * truncated.
 *
 * `GSeekable` on resizable streams is approximately the same as POSIX
 * [`lseek()`](man:lseek(2)) on a normal file.  Seeking past the end and writing
 * data will usually cause the stream to resize by introducing zero bytes.
 **/

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 (positive or zero) offset from the beginning of the
 * buffer, zero if the target is not seekable.
 **/
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: (nullable): optional #GCancellable object, %NULL to ignore.
 * @error: a #GError location to store the error occurring, or %NULL to
 * ignore.
 *
 * Seeks in the stream by the given @offset, modified by @type.
 *
 * Attempting to seek past the end of the stream will have different
 * results depending on if the stream is fixed-sized or resizable.  If
 * the stream is resizable then seeking past the end and then writing
 * will result in zeros filling the empty space.  Seeking past the end
 * of a resizable stream and reading will result in EOF.  Seeking past
 * the end of a fixed-sized stream will fail.
 *
 * Any operation that would result in a negative offset will fail.
 *
 * 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 length of the stream can be adjusted with
 * g_seekable_truncate().
 * 
 * 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: (virtual truncate_fn)
 * @seekable: a #GSeekable.
 * @offset: new length for @seekable, in bytes.
 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore. 
 * @error: a #GError location to store the error occurring, or %NULL to 
 * ignore.
 * 
 * Sets the length of the stream to @offset. If the stream was previously
 * larger than @offset, the extra data is discarded. If the stream was
 * previously shorter than @offset, it is extended with NUL ('\0') bytes.
 * 
 * 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.
 *
 * 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);
}

Line	Count	Source (jump to first uncovered line)
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		#include "gseekable.h"
25		#include "glibintl.h"
26
27
28		/**
29		* GSeekable:
30		*
31		* `GSeekable` is implemented by streams (implementations of
32		* [class@Gio.InputStream] or [class@Gio.OutputStream]) that support seeking.
33		*
34		* Seekable streams largely fall into two categories: resizable and
35		* fixed-size.
36		*
37		* `GSeekable` on fixed-sized streams is approximately the same as POSIX
38		* [`lseek()`](man:lseek(2)) on a block device (for example: attempting to seek
39		* past the end of the device is an error). Fixed streams typically cannot be
40		* truncated.
41		*
42		* `GSeekable` on resizable streams is approximately the same as POSIX
43		* [`lseek()`](man:lseek(2)) on a normal file. Seeking past the end and writing
44		* data will usually cause the stream to resize by introducing zero bytes.
45		**/
46
47		typedef GSeekableIface GSeekableInterface;
48		G_DEFINE_INTERFACE (GSeekable, g_seekable, G_TYPE_OBJECT)
49
50		static void
51		g_seekable_default_init (GSeekableInterface *iface)
52	0	{
53	0	}
54
55		/**
56		* g_seekable_tell:
57		* @seekable: a #GSeekable.
58		*
59		* Tells the current position within the stream.
60		*
61		* Returns: the (positive or zero) offset from the beginning of the
62		* buffer, zero if the target is not seekable.
63		**/
64		goffset
65		g_seekable_tell (GSeekable *seekable)
66	0	{
67	0	GSeekableIface *iface;
68
69	0	g_return_val_if_fail (G_IS_SEEKABLE (seekable), 0);
70
71	0	iface = G_SEEKABLE_GET_IFACE (seekable);
72
73	0	return (* iface->tell) (seekable);
74	0	}
75
76		/**
77		* g_seekable_can_seek:
78		* @seekable: a #GSeekable.
79		*
80		* Tests if the stream supports the #GSeekableIface.
81		*
82		* Returns: %TRUE if @seekable can be seeked. %FALSE otherwise.
83		**/
84		gboolean
85		g_seekable_can_seek (GSeekable *seekable)
86	0	{
87	0	GSeekableIface *iface;
88
89	0	g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
90
91	0	iface = G_SEEKABLE_GET_IFACE (seekable);
92
93	0	return (* iface->can_seek) (seekable);
94	0	}
95
96		/**
97		* g_seekable_seek:
98		* @seekable: a #GSeekable.
99		* @offset: a #goffset.
100		* @type: a #GSeekType.
101		* @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
102		* @error: a #GError location to store the error occurring, or %NULL to
103		* ignore.
104		*
105		* Seeks in the stream by the given @offset, modified by @type.
106		*
107		* Attempting to seek past the end of the stream will have different
108		* results depending on if the stream is fixed-sized or resizable. If
109		* the stream is resizable then seeking past the end and then writing
110		* will result in zeros filling the empty space. Seeking past the end
111		* of a resizable stream and reading will result in EOF. Seeking past
112		* the end of a fixed-sized stream will fail.
113		*
114		* Any operation that would result in a negative offset will fail.
115		*
116		* If @cancellable is not %NULL, then the operation can be cancelled by
117		* triggering the cancellable object from another thread. If the operation
118		* was cancelled, the error %G_IO_ERROR_CANCELLED will be returned.
119		*
120		* Returns: %TRUE if successful. If an error
121		* has occurred, this function will return %FALSE and set @error
122		* appropriately if present.
123		**/
124		gboolean
125		g_seekable_seek (GSeekable *seekable,
126		goffset offset,
127		GSeekType type,
128		GCancellable *cancellable,
129		GError **error)
130	0	{
131	0	GSeekableIface *iface;
132
133	0	g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
134
135	0	iface = G_SEEKABLE_GET_IFACE (seekable);
136
137	0	return (* iface->seek) (seekable, offset, type, cancellable, error);
138	0	}
139
140		/**
141		* g_seekable_can_truncate:
142		* @seekable: a #GSeekable.
143		*
144		* Tests if the length of the stream can be adjusted with
145		* g_seekable_truncate().
146		*
147		* Returns: %TRUE if the stream can be truncated, %FALSE otherwise.
148		**/
149		gboolean
150		g_seekable_can_truncate (GSeekable *seekable)
151	0	{
152	0	GSeekableIface *iface;
153
154	0	g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
155
156	0	iface = G_SEEKABLE_GET_IFACE (seekable);
157
158	0	return (* iface->can_truncate) (seekable);
159	0	}
160
161		/**
162		* g_seekable_truncate: (virtual truncate_fn)
163		* @seekable: a #GSeekable.
164		* @offset: new length for @seekable, in bytes.
165		* @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
166		* @error: a #GError location to store the error occurring, or %NULL to
167		* ignore.
168		*
169		* Sets the length of the stream to @offset. If the stream was previously
170		* larger than @offset, the extra data is discarded. If the stream was
171		* previously shorter than @offset, it is extended with NUL ('\0') bytes.
172		*
173		* If @cancellable is not %NULL, then the operation can be cancelled by
174		* triggering the cancellable object from another thread. If the operation
175		* was cancelled, the error %G_IO_ERROR_CANCELLED will be returned. If an
176		* operation was partially finished when the operation was cancelled the
177		* partial result will be returned, without an error.
178		*
179		* Returns: %TRUE if successful. If an error
180		* has occurred, this function will return %FALSE and set @error
181		* appropriately if present.
182		**/
183		gboolean
184		g_seekable_truncate (GSeekable *seekable,
185		goffset offset,
186		GCancellable *cancellable,
187		GError **error)
188	0	{
189	0	GSeekableIface *iface;
190
191	0	g_return_val_if_fail (G_IS_SEEKABLE (seekable), FALSE);
192
193	0	iface = G_SEEKABLE_GET_IFACE (seekable);
194
195	0	return (* iface->truncate_fn) (seekable, offset, cancellable, error);
196	0	}

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Created: 2025-07-23 08:13