| /* 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); |
| } |