1 /* timer.c --- daemon to provide a tagged interval timer service
3 This little daemon runs forever waiting for signals. SIGIO (or
4 SIGUSR1) causes it to read an event spec from stdin; that is, a
5 date followed by colon followed by an event label. SIGALRM causes
6 it to check its queue for events attached to the current second; if
7 one is found, its label is written to stdout. SIGTERM causes it to
8 terminate, printing a list of pending events.
10 This program is intended to be used with the lisp package called
11 timer.el. It was written anonymously in 1990. This version was
12 documented and rewritten for portability by esr@snark.thyrsus.com,
17 #include <fcntl.h> /* FASYNC */
18 #include <sys/types.h> /* time_t */
20 #include "../src/config.h"
27 extern char *sys_errlist
[], *malloc ();
28 extern time_t time ();
31 * The field separator for input. This character shouldn't be legal in a date,
32 * and should be printable so event strings are readable by people. Was
33 * originally ';', then got changed to bogus `\001'.
42 int events_size
; /* How many slots have we allocated? */
43 int num_events
; /* How many are actually scheduled? */
44 struct event
*events
; /* events[0 .. num_events-1] are the
47 char *pname
; /* programme name for error messages */
49 /* Accepts a string of two fields seperated by FS.
50 First field is string for get_date, saying when to wake-up.
51 Second field is a token to identify the request. */
56 extern time_t get_date ();
57 extern char *strcpy ();
60 static struct event
*ep
;
62 /* check entry format */
63 for (p
= str
; *p
&& *p
!= FS
; p
++)
67 fprintf (stderr
, "%s: bad input format: %s\n", pname
, str
);
72 /* allocate an event slot */
73 ep
= events
+ num_events
;
75 /* If the event array is full, stretch it. After stretching, we know
76 that ep will be pointing to an available event spot. */
77 if (ep
== events
+ events_size
)
79 int old_size
= events_size
;
82 events
= ((struct event
*)
83 realloc (events
, events_size
* sizeof (struct event
)));
86 fprintf (stderr
, "%s: virtual memory exhausted.\n", pname
);
88 /* Should timer exit now? Well, we've still got other
89 events in the queue, and more memory might become
90 available in the future, so we'll just toss this event.
91 This will screw up whoever scheduled the event, but
92 maybe someone else will survive. */
96 while (old_size
< events_size
)
97 events
[old_size
++].token
= NULL
;
100 /* Don't allow users to schedule events in past time. */
101 ep
->reply_at
= get_date (str
, NULL
);
102 if (ep
->reply_at
- time (&now
) < 0)
104 fprintf (stderr
, "%s: bad time spec: %s%c%s\n", pname
, str
, FS
, p
);
108 /* save the event description */
109 ep
->token
= (char *) malloc ((unsigned) strlen (p
) + 1);
112 fprintf (stderr
, "%s: malloc %s: %s%c%s\n",
113 pname
, sys_errlist
[errno
], str
, FS
, p
);
117 strcpy (ep
->token
, p
);
124 time_t now
, tdiff
, waitfor
= -1;
125 register struct event
*ep
;
127 /* If an alarm timer runs out while this function is executing,
128 it could get called recursively. This would be bad, because
129 it's not re-entrant. So we must try to suspend the signal. */
130 #if 0 /* This function isn't right for BSD. Fix it later. */
134 now
= time ((time_t *) NULL
);
136 for (ep
= events
; ep
< events
+ num_events
; ep
++)
137 /* Are any events ready to fire? */
138 if (ep
->reply_at
<= now
)
140 fputs (ep
->token
, stdout
);
145 /* We now have a hole in the event array; fill it with the last
147 ep
->token
= events
[num_events
- 1].token
;
148 ep
->reply_at
= events
[num_events
- 1].reply_at
;
151 /* We ought to scan this event again. */
156 /* next timeout should be the soonest of any remaining */
157 if ((tdiff
= ep
->reply_at
- now
) < waitfor
|| waitfor
< 0)
158 waitfor
= (long)tdiff
;
161 /* If there are no more events, we needn't bother setting an alarm. */
165 #if 0 /* This function isn't right for BSD. */
177 /* In principle the itimer should be disabled on entry to this
178 function, but it really doesn't make any important difference
182 buf
= (char *) malloc (buf_size
);
184 /* Read a line from standard input, expanding buf if it is too short
193 buf
= (char *) realloc (buf
, buf_size
);
195 /* If we're out of memory, toss this event. */
200 while (c
!= '\n' && c
!= EOF
);
219 /* Register the event. */
223 /* Who knows what this interrupted, or if it said "now"? */
230 /* dispatch on incoming signal, then restore it */
243 fprintf (stderr
, "Events still queued:\n");
244 for (ep
= events
; ep
< events
+ num_events
; ep
++)
245 fprintf (stderr
, "%d = %ld @ %s\n",
246 ep
- events
, ep
->reply_at
, ep
->token
);
251 /* required on older UNIXes; harmless on newer ones */
252 signal (sig
, sigcatch
);
261 for (pname
= argv
[0] + strlen (argv
[0]);
262 *pname
!= '/' && pname
!= argv
[0];
268 events
= ((struct event
*) malloc (events_size
* sizeof (*events
)));
271 signal (SIGIO
, sigcatch
);
272 signal (SIGALRM
, sigcatch
);
273 signal (SIGTERM
, sigcatch
);
276 if (fcntl (0, F_SETOWN
, getpid ()) == -1)
278 fprintf (stderr
, "%s: can't set ownership of stdin\n", pname
);
279 fprintf (stderr
, "%s\n", sys_errlist
[errno
]);
282 if (fcntl (0, F_SETFL
, fcntl (0, F_GETFL
, 0) | FASYNC
) == -1)
284 fprintf (stderr
, "%s: can't request asynchronous I/O on stdin\n", pname
);
285 fprintf (stderr
, "%s\n", sys_errlist
[errno
]);
294 /* timer.c ends here */