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#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();
}
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