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  * 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: src/bin/sleep/sleep.c,v 1.20 2005/08/07 09:11:38 stefanf Exp $");
  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 #include <string.h>
  51
  52 void usage(void);
  53
  54 int
  55 main(int argc, char *argv[])
  56 {
  57         struct timespec time_to_sleep;
  58         long l;
  59         int neg;
  60         char *p;
  61
  62         if (argc == 2) {
  63             p = argv[1];
  64         } else if (argc == 3 && !strcmp("--", argv[1])) {
  65             // POSIX issue:   "sleep -- 3" should be the same as "sleep 3",
  66             // normally getopt makes this kind of thing work, but sleep has
  67             // no options, so we do it "the easy way"
  68             p = argv[2];
  69         } else {
  70                 usage();
  71                 return(1);
  72         }
  73
  74         /* Skip over leading whitespaces. */
  75         while (isspace((unsigned char)*p))
  76                 ++p;
  77
  78         /* Check for optional `+' or `-' sign. */
  79         neg = 0;
  80         if (*p == '-') {
  81                 neg = 1;
  82                 ++p;
  83                 if (!isdigit((unsigned char)*p) && *p != '.') {
  84                         usage();
  85                         return(1);
  86                 }
  87         }
  88         else if (*p == '+')
  89                 ++p;
  90
  91         /* Calculate seconds. */
  92         if (isdigit((unsigned char)*p)) {
  93                 l = strtol(p, &p, 10);
  94                 if (l > INT_MAX) {
  95                         /*
  96                          * Avoid overflow when `seconds' is huge.  This assumes
  97                          * that the maximum value for a time_t is <= INT_MAX.
  98                          */
  99                         l = INT_MAX;
 100                 }
 101         } else
 102                 l = 0;
 103         time_to_sleep.tv_sec = (time_t)l;
 104
 105         /* Calculate nanoseconds. */
 106         time_to_sleep.tv_nsec = 0;
 107
 108         if (*p == '.') {                /* Decimal point. */
 109                 l = 100000000L;
 110                 do {
 111                         if (isdigit((unsigned char)*++p))
 112                                 time_to_sleep.tv_nsec += (*p - '0') * l;
 113                         else
 114                                 break;
 115                         l /= 10;
 116                 } while (l);
 117         }
 118
 119         if (!neg && (time_to_sleep.tv_sec > 0 || time_to_sleep.tv_nsec > 0))
 120                 (void)nanosleep(&time_to_sleep, (struct timespec *)NULL);
 121
 122         return(0);
 123 }
 124
 125 void
 126 usage(void)
 127 {
 128         const char msg[] = "usage: sleep seconds\n";
 129
 130         write(STDERR_FILENO, msg, sizeof(msg) - 1);
 131 }