lib-src/timer.c

   1 #include <stdio.h>
   2 #include <signal.h>
   3 #include <fcntl.h>      /* FASYNC */
   4 #ifdef USG              /* FASYNC for SysV */
   5 #include <sys/file.h>
   6 #endif
   7 #include <sys/time.h>   /* itimer */
   8 #include <sys/types.h>  /* time_t */
   9
  10 extern int errno;
  11 extern char *sys_errlist[], *malloc();
  12 extern time_t time();
  13
  14 #define MAXEVENTS 256
  15 #define FS 1           /* field seperator for input */
  16
  17 struct event {
  18   char *token;
  19   time_t reply_at;
  20 } *events[MAXEVENTS];
  21
  22 int slot;         /* The next open place in the events array */
  23 int mevent = 0;   /* 1+ the highest event number */
  24 char *pname;      /* programme name for error messages */
  25
  26 /* Accepts a string of two fields seperated by a ';'
  27  * First field is string for getdate, saying when to wake-up.
  28  * Second field is a token to identify the request.
  29  */
  30 struct event *
  31 schedule(str)
  32      char *str;
  33
  34 {
  35   extern time_t getdate();
  36   extern char *strcpy();
  37   time_t now;
  38   register char *p;
  39   static struct event e;
  40
  41   for(p = str; *p && *p != FS; p++);
  42   if (!*p) {
  43     (void)fprintf(stderr, "%s: bad input format: %s", pname, str);
  44     return((struct event *)NULL);
  45   }
  46   *p++ = 0;
  47
  48   if ((e.reply_at = get_date(str, NULL)) - time(&now) < 0) {
  49     (void)fprintf(stderr, "%s: bad time spec: %s%c%s", pname, str, FS, p);
  50     return((struct event *)NULL);
  51   }
  52
  53   if ((e.token = malloc((unsigned)strlen(p) + 1)) == NULL) {
  54     (void)fprintf(stderr, "%s: malloc %s: %s%c%s",
  55                   pname, sys_errlist[errno], str, FS, p);
  56     return((struct event *)NULL);
  57   }
  58   (void)strcpy(e.token,p);
  59
  60   return(&e);
  61 }
  62
  63 void
  64 notify()
  65
  66 {
  67   time_t now, tdiff;
  68   register int i, newmax = 0;
  69   /* I prefer using the interval timer rather than alarm(); the latter
  70      could be substituted if portability requires it. */
  71   struct itimerval itimer;
  72
  73   now = time((time_t *)NULL);
  74   slot = mevent;
  75   itimer.it_interval.tv_sec = itimer.it_interval.tv_usec = 0;
  76   itimer.it_value.tv_usec = 0;
  77   itimer.it_value.tv_sec = -1;
  78
  79   for(i=0; i < mevent; i++) {
  80     while (events[i] && events[i]->reply_at <= now) {
  81       (void)fputs(events[i]->token, stdout);
  82       free(events[i]->token);
  83       free((char *)events[i]);
  84       events[i] = 0;
  85     }
  86
  87     if (events[i]) {
  88       newmax = i+1;
  89       if ((tdiff = events[i]->reply_at - now) < (time_t)itimer.it_value.tv_sec
  90           || itimer.it_value.tv_sec < 0)
  91         /* next timeout */
  92         itimer.it_value.tv_sec = (long)tdiff;
  93     } else {
  94       /* Keep slot as the lowest unused events element */
  95       if (i < slot) slot = i;
  96     }
  97   }
  98   /* if the array is full to mevent, slot should be the next available spot */
  99   if (slot > (mevent = newmax)) slot = mevent;
 100   /* If there's no more events, SIGIO should be next wake-up */
 101   if (mevent) (void)setitimer(ITIMER_REAL, &itimer, (struct itimerval *)NULL);
 102 }
 103
 104 void
 105 getevent()
 106
 107 {
 108   extern char *fgets();
 109   struct event *ep;
 110   char buf[256];
 111
 112   /* in principle the itimer should be disabled on entry to this function,
 113      but it really doesn't make any important difference if it isn't */
 114
 115   if (fgets(buf, sizeof(buf), stdin) == NULL) exit(0);
 116
 117   if (slot == MAXEVENTS)
 118     (void)fprintf(stderr, "%s: too many events: %s", pname, buf);
 119
 120   else {
 121     if ((events[slot] = (struct event *)malloc((sizeof(struct event))))
 122         == NULL)
 123       (void)fprintf(stderr,"%s: malloc %s: %s", pname, sys_errlist[errno],buf);
 124
 125     else {
 126       if ((ep = schedule(buf)) == NULL)
 127         free((char *)events[slot]), events[slot] = 0;
 128
 129       else {
 130         memcpy((char *)events[slot],(char *)ep,sizeof(struct event));
 131         if (slot == mevent) mevent++;
 132       } /* schedule */
 133     } /* malloc */
 134   } /* limit events */
 135   /* timing, timing.  Who knows what this interrupted, or if it said "now"? */
 136   notify();
 137 }
 138
 139 /*ARGSUSED*/
 140 int
 141 main(argc, argv)
 142      int argc;
 143      char **argv;
 144
 145 {
 146   for (pname = argv[0] + strlen(argv[0]); *pname != '/' && pname != argv[0];
 147        pname--);
 148   if (*pname == '/') pname++;
 149
 150   (void)signal(SIGIO, getevent);
 151   (void)signal(SIGALRM, notify);
 152   (void)fcntl(0, F_SETFL, FASYNC);
 153
 154   while (1) pause();
 155 }