bin/sleep/sleep.c

   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. 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  * @(#) Copyright (c) 1988, 1993, 1994 The Regents of the University of California.  All rights reserved.
  30  * @(#)sleep.c  8.3 (Berkeley) 4/2/94
  31  * $FreeBSD: src/bin/sleep/sleep.c,v 1.9.2.1 2001/08/01 05:23:25 obrien Exp $
  32  * $DragonFly: src/bin/sleep/sleep.c,v 1.7 2005/02/27 15:57:15 liamfoy Exp $
  33  */
  34
  35 #include <ctype.h>
  36 #include <limits.h>
  37 #include <locale.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <time.h>
  41 #include <unistd.h>
  42
  43 static void usage(void);
  44
  45 int
  46 main(int argc, char **argv)
  47 {
  48         struct timespec time_to_sleep;
  49         long l;
  50         int ch, neg;
  51         char *p;
  52
  53         setlocale(LC_ALL, "");
  54
  55         while ((ch = getopt(argc, argv, "")) != -1)
  56                 switch(ch) {
  57                 default:
  58                         usage();
  59                         /* NOTREACHED */
  60                 }
  61         argc -= optind;
  62         argv += optind;
  63
  64         if (argc != 1) {
  65                 usage();
  66                 /* NOTREACHED */
  67         }
  68
  69         p = argv[0];
  70
  71         /* Skip over leading whitespaces. */
  72         while (isspace(*p))
  73                 ++p;
  74
  75         /* Check for optional `+' or `-' sign. */
  76         neg = 0;
  77         if (*p == '-') {
  78                 neg = 1;
  79                 ++p;
  80         }
  81         else if (*p == '+')
  82                 ++p;
  83
  84         /* Calculate seconds. */
  85         if (isdigit(*p)) {
  86                 l = strtol(p, &p, 10);
  87                 if (l > INT_MAX) {
  88                         /*
  89                          * Avoid overflow when `seconds' is huge.  This assumes
  90                          * that the maximum value for a time_t is <= INT_MAX.
  91                          */
  92                         l = INT_MAX;
  93                 }
  94         } else
  95                 l = 0;
  96         time_to_sleep.tv_sec = (time_t)l;
  97
  98         /* Calculate nanoseconds. */
  99         time_to_sleep.tv_nsec = 0;
 100
 101         if (*p == '.') {                /* Decimal point. */
 102                 l = 100000000L;
 103                 do {
 104                         if (isdigit(*++p))
 105                                 time_to_sleep.tv_nsec += (*p - '0') * l;
 106                         else
 107                                 break;
 108                 } while (l /= 10);
 109         }
 110
 111         if (!neg && (time_to_sleep.tv_sec > 0 || time_to_sleep.tv_nsec > 0))
 112                 nanosleep(&time_to_sleep, NULL);
 113
 114         exit(0);
 115 }
 116
 117 static void
 118 usage(void)
 119 {
 120         fprintf(stderr, "usage: sleep seconds\n");
 121         exit(1);
 122 }