xref: /freebsd/bin/sleep/sleep.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
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  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #if 0
31 #ifndef lint
32 static char const copyright[] =
33 "@(#) Copyright (c) 1988, 1993, 1994\n\
34 	The Regents of the University of California.  All rights reserved.\n";
35 #endif /* not lint */
36 
37 #ifndef lint
38 static char sccsid[] = "@(#)sleep.c	8.3 (Berkeley) 4/2/94";
39 #endif /* not lint */
40 #endif
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD$");
43 
44 #include <ctype.h>
45 #include <limits.h>
46 #include <stdio.h>
47 #include <stdlib.h>
48 #include <time.h>
49 #include <unistd.h>
50 
51 void usage(void);
52 
53 int
54 main(int argc, char *argv[])
55 {
56 	struct timespec time_to_sleep;
57 	long l;
58 	int neg;
59 	char *p;
60 
61 	if (argc != 2) {
62 		usage();
63 		return(1);
64 	}
65 
66 	p = argv[1];
67 
68 	/* Skip over leading whitespaces. */
69 	while (isspace((unsigned char)*p))
70 		++p;
71 
72 	/* Check for optional `+' or `-' sign. */
73 	neg = 0;
74 	if (*p == '-') {
75 		neg = 1;
76 		++p;
77 		if (!isdigit((unsigned char)*p) && *p != '.') {
78 			usage();
79 			return(1);
80 		}
81 	}
82 	else if (*p == '+')
83 		++p;
84 
85 	/* Calculate seconds. */
86 	if (isdigit((unsigned char)*p)) {
87 		l = strtol(p, &p, 10);
88 		if (l > INT_MAX) {
89 			/*
90 			 * Avoid overflow when `seconds' is huge.  This assumes
91 			 * that the maximum value for a time_t is <= INT_MAX.
92 			 */
93 			l = INT_MAX;
94 		}
95 	} else
96 		l = 0;
97 	time_to_sleep.tv_sec = (time_t)l;
98 
99 	/* Calculate nanoseconds. */
100 	time_to_sleep.tv_nsec = 0;
101 
102 	if (*p == '.') {		/* Decimal point. */
103 		l = 100000000L;
104 		do {
105 			if (isdigit((unsigned char)*++p))
106 				time_to_sleep.tv_nsec += (*p - '0') * l;
107 			else
108 				break;
109 			l /= 10;
110 		} while (l);
111 	}
112 
113 	if (!neg && (time_to_sleep.tv_sec > 0 || time_to_sleep.tv_nsec > 0))
114 		(void)nanosleep(&time_to_sleep, (struct timespec *)NULL);
115 
116 	return(0);
117 }
118 
119 void
120 usage(void)
121 {
122 	const char msg[] = "usage: sleep seconds\n";
123 
124 	write(STDERR_FILENO, msg, sizeof(msg) - 1);
125 }
126