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/*
* timer.c --- daemon to provide a tagged interval timer service
*
* This little daemon runs forever waiting for signals. SIGIO (or SIGUSR1)
* causes it to read an event spec from stdin; that is, a date followed by
* colon followed by an event label. SIGALRM causes it to check its queue
* for events attached to the current second; if one is found, its label
* is written to stdout. SIGTERM causes it to terminate, printing a list
* of pending events.
*
* This program is intended to be used with the lisp package called timer.el.
* It was written anonymously in 1990. This version was documented and
* rewritten for portability by esr@snark,thyrsus.com, Aug 7 1992.
*/
#include <stdio.h>
#include <signal.h>
#include <fcntl.h> /* FASYNC */
#include <sys/types.h> /* time_t */
#include "../src/config.h"
#ifdef USG
#undef SIGIO
#define SIGIO SIGUSR1
#endif
extern int errno;
extern char *sys_errlist[], *malloc();
extern time_t time();
#define MAXEVENTS 256
/*
* The field separator for input. This character shouldn't be legal in a date,
* and should be printable so event strings are readable by people. Was
* originally ';', then got changed to bogus `\001'.
*/
#define FS '@'
struct event
{
char *token;
time_t reply_at;
}
events[MAXEVENTS];
char *pname; /* programme name for error messages */
/* Accepts a string of two fields seperated by FS.
* First field is string for getdate, saying when to wake-up.
* Second field is a token to identify the request.
*/
void schedule(str)
char *str;
{
extern time_t getdate();
extern char *strcpy();
time_t now;
register char *p;
static struct event *ep;
#ifdef DEBUG
(void) fprintf(stderr, "Timer sees: %s", str);
#endif /* DEBUG */
/* check entry format */
for(p = str; *p && *p != FS; p++)
continue;
if (!*p)
{
(void)fprintf(stderr, "%s: bad input format: %s", pname, str);
return;
}
*p++ = 0;
/* allocate an event slot */
for(ep = events; ep < events + MAXEVENTS; ep++)
if (ep->token == (char *)NULL)
break;
if (ep == events + MAXEVENTS)
(void) fprintf(stderr, "%s: too many events: %s", pname, str);
/* don't allow users to schedule events in past time */
else if ((ep->reply_at = get_date(str, NULL)) - time(&now) < 0)
(void)fprintf(stderr, "%s: bad time spec: %s%c%s", pname, str, FS, p);
/* save the event description */
else if ((ep->token = malloc((unsigned)strlen(p) + 1)) == NULL)
(void)fprintf(stderr, "%s: malloc %s: %s%c%s",
pname, sys_errlist[errno], str, FS, p);
else
{
(void)strcpy(ep->token, p);
#ifdef DEBUG
(void) fprintf(stderr,
"New event: %ld: %s", ep->reply_at, ep->token);
#endif /* DEBUG */
}
}
void
notify()
{
time_t now, tdiff, waitfor = -1;
register struct event *ep;
now = time((time_t *)NULL);
for(ep = events; ep < events + MAXEVENTS; ep++)
if (ep->token)
{
/* any events ready to fire? */
if (ep->reply_at <= now)
{
#ifdef DEBUG
(void) fprintf(stderr,
"Event %d firing: %ld @ %s",
(ep - events), ep->reply_at, ep->token);
#endif /* DEBUG */
(void)fputs(ep->token, stdout);
free(ep->token);
ep->token = (char *)NULL;
}
else
{
#ifdef DEBUG
(void) fprintf(stderr,
"Event %d still waiting: %ld @ %s",
(ep - events), ep->reply_at, ep->token);
#endif /* DEBUG */
/* next timeout should be the soonest of any remaining */
if ((tdiff = ep->reply_at - now) < waitfor || waitfor < 0)
waitfor = (long)tdiff;
}
}
/* If there's no more events, SIGIO should be next wake-up */
if (waitfor != -1)
{
#ifdef DEBUG
(void) fprintf(stderr,
"Setting %d-second alarm\n", waitfor);
#endif /* DEBUG */
(void)alarm(waitfor);
}
}
void
getevent()
{
extern char *fgets();
struct event *ep;
char buf[BUFSIZ];
/* 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);
/* register the event */
schedule(buf);
/* Who knows what this interrupted, or if it said "now"? */
notify();
}
void
sigcatch(sig)
/* dispatch on incoming signal, then restore it */
{
struct event *ep;
switch(sig)
{
case SIGALRM:
#ifdef DEBUG
(void) fprintf(stderr, "Alarm signal received\n");
#endif /* DEBUG */
notify();
break;
case SIGIO:
getevent();
break;
case SIGTERM:
(void) fprintf(stderr, "Events still queued:\n");
for (ep = events; ep < events + MAXEVENTS; ep++)
if (ep->token)
(void) fprintf(stderr, "%d = %ld @ %s",
ep - events, ep->reply_at, ep->token);
exit(0);
break;
}
/* required on older UNIXes; harmless on newer ones */
(void) signal(sig, sigcatch);
}
/*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, sigcatch);
(void)signal(SIGALRM, sigcatch);
(void)signal(SIGTERM, sigcatch);
#ifndef USG
(void)fcntl(0, F_SETFL, FASYNC);
#endif /* USG */
while (1) pause();
}
/* timer.c ends here */
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