xref: /src/lib/libc/gen/_errno.c

/*	$NetBSD: _errno.c,v 1.9.2.1 2001/08/08 18:29:50 nathanw Exp $	*/

/*-
 * Copyright (c) 1996 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by J.T. Conklin.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *        This product includes software developed by the NetBSD
 *        Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "reentrant.h"
#include <errno.h>
#include <stdlib.h>

#undef errno
extern int errno;

#ifdef _REENTRANT
static thread_key_t __errno_key;
static once_t __errno_key_once = ONCE_INITIALIZER;

static void
__errno_key_setup(void)
{
	thr_keycreate(&__errno_key, free);
}
#endif

int *
__errno(void)
{
#ifdef _REENTRANT
	int *eaddr;
	extern int __isthreaded;

	if (__isthreaded == 0)
		return &errno;
	thr_once(&__errno_key_once, __errno_key_setup);
	eaddr = thr_getspecific(__errno_key);
	if (eaddr == NULL) {
		eaddr = malloc(sizeof(int));
		if (eaddr == NULL)
			return &errno;
		thr_setspecific(__errno_key, eaddr);
	}
	return eaddr;
#else
	return &errno;
#endif
}