/*
 * Copyright © 2024 Nick Bowler
 *
 * Helpers for hosts using POSIX threading (pthreads) API.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <pthread.h>

#if USE_POSIX_THREADS_WEAK
#  pragma weak pthread_key_create
#  pragma weak pthread_getspecific
#  pragma weak pthread_setspecific
#endif

static struct {
	union {
		pthread_key_t mt;
#if USE_POSIX_THREADS_WEAK
		void *st;
#endif
	} u;

#if USE_POSIX_THREADS_WEAK
	signed char valid;
#else
	bool valid;
#endif
} tls_key;
#define tls_key_valid (tls_key.valid != 0)

static void tls_key_init(void)
{
	if (pthread_in_use())
		tls_key.valid = !pthread_key_create(&tls_key.u.mt, free);
	else
		tls_key.valid = -1;
}

static void *tls_get(void)
{
#if USE_POSIX_THREADS_WEAK
	if (tls_key.valid < 0)
		return tls_key.u.st;
#endif
	return pthread_getspecific(tls_key.u.mt);
}

static int tls_set(void *p)
{
#if USE_POSIX_THREADS_WEAK
	if (tls_key.valid < 0)
		return (tls_key.u.st = p, 1);
#endif
	return !pthread_setspecific(tls_key.u.mt, p);
}