xref: /freebsd-10.3-release/lib/libc/gen/ualarm.c

/*
 * Copyright (c) 1985, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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.
 * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)ualarm.c	8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: releng/10.3/lib/libc/gen/ualarm.c 165903 2007-01-09 00:28:16Z imp $");

#include <sys/time.h>
#include <unistd.h>

#define	USPS	1000000		/* # of microseconds in a second */

/*
 * Generate a SIGALRM signal in ``usecs'' microseconds.
 * If ``reload'' is non-zero, keep generating SIGALRM
 * every ``reload'' microseconds after the first signal.
 */
useconds_t
ualarm(usecs, reload)
	useconds_t usecs;
	useconds_t reload;
{
	struct itimerval new, old;

	new.it_interval.tv_usec = reload % USPS;
	new.it_interval.tv_sec = reload / USPS;

	new.it_value.tv_usec = usecs % USPS;
	new.it_value.tv_sec = usecs / USPS;

	if (setitimer(ITIMER_REAL, &new, &old) == 0)
		return (old.it_value.tv_sec * USPS + old.it_value.tv_usec);
	/* else */
		return (-1);
}