sys/src/cmd/alarm.c

   1 /*
   2 *       alarm
   3 *
   4 *       you may think some rc script can be same effect
   5 *       I did but I realized rc script does not work cleanly.
   6 *       The bellowing has a problem. so I wrote in C
   7 *       -Kenar-
   8 *
   9 *       #!/bin/rc
  10 *       if(~ $* 0 1)
  11 *               echo usage: alarm time command arg ...
  12 *       rfork e
  13 *       t=$1
  14 *       shift
  15 *       c=$*
  16 *       {       sleep $t;
  17 *               if(test -e /proc/$pid)
  18 *                       echo alarm >/proc/$pid/note
  19 *       }&
  20 *       exec $c
  21 *
  22 */
  23
  24 #include <u.h>
  25 #include <libc.h>
  26
  27 void
  28 usage(void)
  29 {
  30         fprint(2,"usage: %s time command [ arg ... ]\n", argv0);
  31         exits("usage");
  32 }
  33
  34 static void
  35 catch(void *, char *msg)
  36 {
  37         postnote(PNGROUP, getpid(), msg);
  38         noted(NDFLT);
  39 }
  40
  41 void
  42 main(int argc, char *argv[])
  43 {
  44         char buf[1024], *p, *q;
  45         Waitmsg *w;
  46         long n, t;
  47
  48         argv0 = argv[0];
  49         if(argc < 3)
  50                 usage();
  51         n = strtol(argv[1], &p, 10);
  52         if(n < 0)
  53                 usage();
  54         t = n * 1000;
  55         if(*p++ == '.' && (n = strtol(p, &q, 10)) > 0){
  56                 switch(q - p){
  57                 case 0:
  58                         break;
  59                 case 1:
  60                         n *= 100;
  61                         break;
  62                 case 2:
  63                         n *= 10;
  64                         break;
  65                 default:
  66                         p[3] = 0;
  67                         n = strtol(p, 0, 10);
  68                         break;
  69                 }
  70                 t += n;
  71         }
  72         rfork(RFNOTEG);
  73         switch(rfork(RFFDG|RFREND|RFPROC|RFMEM)){
  74         case -1:
  75                 sysfatal("%r");
  76         case 0: /* child */
  77                 exec(argv[2], &argv[2]);
  78                 if(argv[2][0] != '/' && strncmp(argv[2], "./", 2) &&
  79                    strncmp(argv[2], "../", 3)){
  80                         snprint(buf, sizeof(buf), "/bin/%s", argv[2]);
  81                         exec(argv[2] = buf, &argv[2]);
  82                 }
  83                 sysfatal("%s: %r", argv[2]);
  84         }
  85         notify(catch);
  86         alarm(t);
  87         if(w = wait())
  88                 exits(w->msg);
  89         exits("alarm");
  90 }