Initial revision

lib-src/timer.c

@@ -0,0 +1,155 @@
+#include <stdio.h>
+#include <signal.h>
+#include <fcntl.h>      /* FASYNC */
+#ifdef USG              /* FASYNC for SysV */
+#include <sys/file.h>
+#endif
+#include <sys/time.h>   /* itimer */
+#include <sys/types.h>  /* time_t */
+
+extern int errno;
+extern char *sys_errlist[], *malloc();
+extern time_t time();
+
+#define MAXEVENTS 256
+#define FS 1           /* field seperator for input */
+
+struct event {
+  char *token;
+  time_t reply_at;
+} *events[MAXEVENTS];
+
+int slot;         /* The next open place in the events array */
+int mevent = 0;   /* 1+ the highest event number */
+char *pname;      /* programme name for error messages */
+
+/* Accepts a string of two fields seperated by a ';'
+ * First field is string for getdate, saying when to wake-up.
+ * Second field is a token to identify the request.
+ */
+struct event *
+schedule(str)
+     char *str;
+
+{
+  extern time_t getdate();
+  extern char *strcpy();
+  time_t now;
+  register char *p;
+  static struct event e;
+
+  for(p = str; *p && *p != FS; p++);
+  if (!*p) {
+    (void)fprintf(stderr, "%s: bad input format: %s", pname, str);
+    return((struct event *)NULL);
+  }
+  *p++ = 0;
+  
+  if ((e.reply_at = getdate(str, NULL)) - time(&now) < 0) {
+    (void)fprintf(stderr, "%s: bad time spec: %s%c%s", pname, str, FS, p);
+    return((struct event *)NULL);
+  }
+
+  if ((e.token = malloc((unsigned)strlen(p) + 1)) == NULL) {
+    (void)fprintf(stderr, "%s: malloc %s: %s%c%s",
+                  pname, sys_errlist[errno], str, FS, p);
+    return((struct event *)NULL);
+  }
+  (void)strcpy(e.token,p);
+
+  return(&e);
+}
+
+void
+notify()
+
+{
+  time_t now, tdiff;
+  register int i, newmax = 0;
+  /* I prefer using the interval timer rather than alarm(); the latter
+     could be substituted if portability requires it. */
+  struct itimerval itimer;
+
+  now = time((time_t *)NULL);
+  slot = mevent;
+  itimer.it_interval.tv_sec = itimer.it_interval.tv_usec = 0;
+  itimer.it_value.tv_usec = 0;
+  itimer.it_value.tv_sec = -1;
+
+  for(i=0; i < mevent; i++) {
+    while (events[i] && events[i]->reply_at <= now) {
+      (void)fputs(events[i]->token, stdout);
+      free(events[i]->token);
+      free((char *)events[i]);
+      events[i] = 0;
+    }
+
+    if (events[i]) {
+      newmax = i+1;
+      if ((tdiff = events[i]->reply_at - now) < (time_t)itimer.it_value.tv_sec
+          || itimer.it_value.tv_sec < 0)
+        /* next timeout */
+        itimer.it_value.tv_sec = (long)tdiff;
+    } else {
+      /* Keep slot as the lowest unused events element */
+      if (i < slot) slot = i;
+    }
+  }
+  /* if the array is full to mevent, slot should be the next available spot */
+  if (slot > (mevent = newmax)) slot = mevent;
+  /* If there's no more events, SIGIO should be next wake-up */
+  if (mevent) (void)setitimer(ITIMER_REAL, &itimer, (struct itimerval *)NULL);
+}
+
+void
+getevent()
+
+{
+  extern char *memcpy(), *fgets();
+  struct event *ep;
+  char buf[256];
+
+  /* in principle the itimer should be disabled on entry to this function,
+     but it really doesn't make any important difference if it isn't */
+
+  if (fgets(buf, sizeof(buf), stdin) == NULL) exit(0);
+
+  if (slot == MAXEVENTS)
+    (void)fprintf(stderr, "%s: too many events: %s", pname, buf);
+
+  else {
+    if ((events[slot] = (struct event *)malloc((sizeof(struct event))))
+        == NULL)
+      (void)fprintf(stderr,"%s: malloc %s: %s", pname, sys_errlist[errno],buf);
+
+    else {
+      if ((ep = schedule(buf)) == NULL)
+        free((char *)events[slot]), events[slot] = 0;
+
+      else {
+        (void)memcpy((char *)events[slot],(char *)ep,sizeof(struct event));
+        if (slot == mevent) mevent++;
+      } /* schedule */
+    } /* malloc */
+  } /* limit events */
+  /* timing, timing.  Who knows what this interrupted, or if it said "now"? */
+  notify();
+}
+ 
+/*ARGSUSED*/
+int
+main(argc, argv)
+     int argc;
+     char **argv;
+
+{
+  for (pname = argv[0] + strlen(argv[0]); *pname != '/' && pname != argv[0];
+       pname--);
+  if (*pname == '/') pname++;
+
+  (void)signal(SIGIO, getevent);
+  (void)signal(SIGALRM, notify);
+  (void)fcntl(0, F_SETFL, FASYNC);
+
+  while (1) pause();
+}