sleep.c revision 114433 
1/*
2 * Copyright (c) 1988, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#if 0
35#ifndef lint
36static char const copyright[] =
37"@(#) Copyright (c) 1988, 1993, 1994\n\
38	The Regents of the University of California.  All rights reserved.\n";
39#endif /* not lint */
40
41#ifndef lint
42static char sccsid[] = "@(#)sleep.c	8.3 (Berkeley) 4/2/94";
43#endif /* not lint */
44#endif
45#include <sys/cdefs.h>
46__FBSDID("$FreeBSD: head/bin/sleep/sleep.c 114433 2003-05-01 16:58:57Z obrien $");
47
48#include <ctype.h>
49#include <limits.h>
50#include <stdlib.h>
51#include <time.h>
52#include <unistd.h>
53#include <string.h>
54
55void usage(void);
56
57int
58main(int argc, char *argv[])
59{
60	struct timespec time_to_sleep;
61	long l;
62	int neg;
63	char *p;
64
65	if (argc != 2) {
66		usage();
67		/* NOTREACHED */
68	}
69
70	p = argv[1];
71
72	/* Skip over leading whitespaces. */
73	while (isspace((unsigned char)*p))
74		++p;
75
76	/* Check for optional `+' or `-' sign. */
77	neg = 0;
78	if (*p == '-') {
79		neg = 1;
80		++p;
81		if (!isdigit((unsigned char)*p) && *p != '.')
82			usage();
83			/* NOTREACHED */
84	}
85	else if (*p == '+')
86		++p;
87
88	/* Calculate seconds. */
89	if (isdigit((unsigned char)*p)) {
90		l = strtol(p, &p, 10);
91		if (l > INT_MAX) {
92			/*
93			 * Avoid overflow when `seconds' is huge.  This assumes
94			 * that the maximum value for a time_t is >= INT_MAX.
95			 */
96			l = INT_MAX;
97		}
98	} else
99		l = 0;
100	time_to_sleep.tv_sec = (time_t)l;
101
102	/* Calculate nanoseconds. */
103	time_to_sleep.tv_nsec = 0;
104
105	if (*p == '.') {		/* Decimal point. */
106		l = 100000000L;
107		do {
108			if (isdigit((unsigned char)*++p))
109				time_to_sleep.tv_nsec += (*p - '0') * l;
110			else
111				break;
112		} while (l /= 10);
113	}
114
115	if (!neg && (time_to_sleep.tv_sec > 0 || time_to_sleep.tv_nsec > 0))
116		(void)nanosleep(&time_to_sleep, (struct timespec *)NULL);
117
118	exit(0);
119}
120
121void
122usage(void)
123{
124	const char *msg = "usage: sleep seconds\n";
125
126	write(STDERR_FILENO, msg, strlen(msg));
127	exit(1);
128}
129