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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
*
* Copyright (C) 2012 Colin Walters <walters@verbum.org>
*
* 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.
*/
#include "config.h"
#include "gsystem-local-alloc.h"
/**
* SECTION:gslocalalloc
* @title: GSystem local allocation
* @short_description: Release local variables automatically when they go out of scope
*
* These macros leverage the GCC extension __attribute__ ((cleanup))
* to allow calling a cleanup function such as g_free() when a
* variable goes out of scope. See <ulink
* url="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html">
* for more information on the attribute.
*
* The provided macros make it easy to use the cleanup attribute for
* types that come with GLib. The primary two are #gs_free and
* #gs_unref_object, which correspond to g_free() and
* g_object_unref(), respectively.
*
* The rationale behind this is that particularly when handling error
* paths, it can be very tricky to ensure the right variables are
* freed. With this, one simply applies gs_lobj to a
* locally-allocated #GFile for example, and it will be automatically
* unreferenced when it goes out of scope.
*
* Note - you should only use these macros for <emphasis>stack
* allocated</emphasis> variables. They don't provide garbage
* collection or let you avoid freeing things. They're simply a
* compiler assisted deterministic mechanism for calling a cleanup
* function when a stack frame ends.
*
* <example id="gs-lfree"><title>Calling g_free automatically</title>
* <programlisting>
*
* GFile *
* create_file (GError **error)
* {
* gs_free char *random_id = NULL;
*
* if (!prepare_file (error))
* return NULL;
*
* random_id = alloc_random_id ();
*
* return create_file_real (error);
* // Note that random_id is freed here automatically
* }
* </programlisting>
* </example>
*
*/
void
gs_local_free (void *loc)
{
void **location = loc;
if (location)
g_free (*location);
}
#define _gs_local_free(type, function) do { \
void **location = loc; \
if (location) \
{ \
type *value = *location; \
if (value) \
function (value); \
} \
} while (0)
void
gs_local_obj_unref (void *loc)
{
_gs_local_free(GObject, g_object_unref);
}
void
gs_local_variant_unref (void *loc)
{
_gs_local_free(GVariant, g_variant_unref);
}
void
gs_local_variant_iter_free (void *loc)
{
_gs_local_free(GVariantIter, g_variant_iter_free);
}
void
gs_local_ptrarray_unref (void *loc)
{
_gs_local_free(GPtrArray, g_ptr_array_unref);
}
void
gs_local_array_unref (void *loc)
{
_gs_local_free(GArray, g_array_unref);
}
void
gs_local_hashtable_unref (void *loc)
{
_gs_local_free(GHashTable, g_hash_table_unref);
}
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