xref: /netbsd-src/lib/libpthread/pthread_specific.c (revision 568eb77ef2a2b1fbe2457d69c7aa6e1dd3d8de8b)

/*	$NetBSD: pthread_specific.c,v 1.28 2022/04/10 10:38:33 riastradh Exp $	*/

/*-
 * Copyright (c) 2001, 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Nathan J. Williams.
 *
 * 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.
 *
 * 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 <sys/cdefs.h>
__RCSID("$NetBSD: pthread_specific.c,v 1.28 2022/04/10 10:38:33 riastradh Exp $");

/* Need to use libc-private names for atomic operations. */
#include "../../common/lib/libc/atomic/atomic_op_namespace.h"

/* Functions and structures dealing with thread-specific data */

#include "pthread.h"
#include "pthread_int.h"
#include "reentrant.h"

#include <string.h>
#include <sys/lwpctl.h>

#include "../libc/include/extern.h" /* for _sys_setcontext() */

int	pthread_setcontext(const ucontext_t *);

__strong_alias(__libc_thr_setspecific,pthread_setspecific)
__strong_alias(__libc_thr_getspecific,pthread_getspecific)
__strong_alias(__libc_thr_curcpu,pthread_curcpu_np)

__strong_alias(setcontext,pthread_setcontext)

int
pthread_setspecific(pthread_key_t key, const void *value)
{
	pthread_t self;

	if (__predict_false(__uselibcstub))
		return __libc_thr_setspecific_stub(key, value);

	self = pthread__self();
	/*
	 * We can't win here on constness. Having been given a
	 * "const void *", we can only assign it to other const void *,
	 * and return it from functions that are const void *, without
	 * generating a warning.
	 */
	return pthread__add_specific(self, key, value);
}

void *
pthread_getspecific(pthread_key_t key)
{
	if (__predict_false(__uselibcstub))
		return __libc_thr_getspecific_stub(key);

	return pthread__self()->pt_specific[key].pts_value;
}

unsigned int
pthread_curcpu_np(void)
{
	if (__predict_false(__uselibcstub))
		return __libc_thr_curcpu_stub();

	{
		const int curcpu = pthread__self()->pt_lwpctl->lc_curcpu;

		pthread__assert(curcpu != LWPCTL_CPU_NONE);
		pthread__assert(curcpu != LWPCTL_CPU_EXITED);
		pthread__assert(curcpu >= 0);
		return curcpu;
	}
}

/*
 * Override setcontext so that pthread private pointer is preserved
 */
int
pthread_setcontext(const ucontext_t *ucp)
{
#ifdef _UC_TLSBASE
	ucontext_t uc;
	/*
	 * Only copy and clear _UC_TLSBASE if it is set.
	 */
	if (ucp->uc_flags & _UC_TLSBASE) {
		uc = *ucp;
		uc.uc_flags &= ~_UC_TLSBASE;
		ucp = &uc;
	}
#endif /* _UC_TLSBASE */
	return _sys_setcontext(ucp);
}