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glnx-backport-autoptr.h
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glnx-backport-autoptr.h
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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
*
* Copyright (C) 2015 Colin Walters <[email protected]>
* SPDX-License-Identifier: LGPL-2.0-or-later
*
* GLIB - Library of useful routines for C programming
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* 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.
*/
#pragma once
#include <gio/gio.h>
G_BEGIN_DECLS
#if !GLIB_CHECK_VERSION(2, 43, 4)
#define _GLIB_AUTOPTR_FUNC_NAME(TypeName) glib_autoptr_cleanup_##TypeName
#define _GLIB_AUTOPTR_TYPENAME(TypeName) TypeName##_autoptr
#define _GLIB_AUTO_FUNC_NAME(TypeName) glib_auto_cleanup_##TypeName
#define _GLIB_CLEANUP(func) __attribute__((cleanup(func)))
#define _GLIB_DEFINE_AUTOPTR_CHAINUP(ModuleObjName, ParentName) \
typedef ModuleObjName *_GLIB_AUTOPTR_TYPENAME(ModuleObjName); \
static inline void _GLIB_AUTOPTR_FUNC_NAME(ModuleObjName) (ModuleObjName **_ptr) { \
_GLIB_AUTOPTR_FUNC_NAME(ParentName) ((ParentName **) _ptr); } \
/* these macros are API */
#define G_DEFINE_AUTOPTR_CLEANUP_FUNC(TypeName, func) \
typedef TypeName *_GLIB_AUTOPTR_TYPENAME(TypeName); \
G_GNUC_BEGIN_IGNORE_DEPRECATIONS \
static inline void _GLIB_AUTOPTR_FUNC_NAME(TypeName) (TypeName **_ptr) { if (*_ptr) (func) (*_ptr); } \
G_GNUC_END_IGNORE_DEPRECATIONS
#define G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(TypeName, func) \
G_GNUC_BEGIN_IGNORE_DEPRECATIONS \
static inline void _GLIB_AUTO_FUNC_NAME(TypeName) (TypeName *_ptr) { (func) (_ptr); } \
G_GNUC_END_IGNORE_DEPRECATIONS
#define G_DEFINE_AUTO_CLEANUP_FREE_FUNC(TypeName, func, none) \
G_GNUC_BEGIN_IGNORE_DEPRECATIONS \
static inline void _GLIB_AUTO_FUNC_NAME(TypeName) (TypeName *_ptr) { if (*_ptr != none) (func) (*_ptr); } \
G_GNUC_END_IGNORE_DEPRECATIONS
#define g_autoptr(TypeName) _GLIB_CLEANUP(_GLIB_AUTOPTR_FUNC_NAME(TypeName)) _GLIB_AUTOPTR_TYPENAME(TypeName)
#define g_auto(TypeName) _GLIB_CLEANUP(_GLIB_AUTO_FUNC_NAME(TypeName)) TypeName
#define g_autofree _GLIB_CLEANUP(g_autoptr_cleanup_generic_gfree)
/**
* g_steal_pointer:
* @pp: a pointer to a pointer
*
* Sets @pp to %NULL, returning the value that was there before.
*
* Conceptually, this transfers the ownership of the pointer from the
* referenced variable to the "caller" of the macro (ie: "steals" the
* reference).
*
* The return value will be properly typed, according to the type of
* @pp.
*
* This can be very useful when combined with g_autoptr() to prevent the
* return value of a function from being automatically freed. Consider
* the following example (which only works on GCC and clang):
*
* |[
* GObject *
* create_object (void)
* {
* g_autoptr(GObject) obj = g_object_new (G_TYPE_OBJECT, NULL);
*
* if (early_error_case)
* return NULL;
*
* return g_steal_pointer (&obj);
* }
* ]|
*
* It can also be used in similar ways for 'out' parameters and is
* particularly useful for dealing with optional out parameters:
*
* |[
* gboolean
* get_object (GObject **obj_out)
* {
* g_autoptr(GObject) obj = g_object_new (G_TYPE_OBJECT, NULL);
*
* if (early_error_case)
* return FALSE;
*
* if (obj_out)
* *obj_out = g_steal_pointer (&obj);
*
* return TRUE;
* }
* ]|
*
* In the above example, the object will be automatically freed in the
* early error case and also in the case that %NULL was given for
* @obj_out.
*
* Since: 2.44
*/
static inline gpointer
(g_steal_pointer) (gpointer pp)
{
gpointer *ptr = (gpointer *) pp;
gpointer ref;
ref = *ptr;
*ptr = NULL;
return ref;
}
/* type safety */
#define g_steal_pointer(pp) \
(0 ? (*(pp)) : (g_steal_pointer) (pp))
#endif /* !GLIB_CHECK_VERSION(2, 43, 3) */
G_END_DECLS