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[emacs/old-mirror.git] / lib-src / =timer.c
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1 /* timer.c --- daemon to provide a tagged interval timer service
3 This little daemon runs forever waiting for commands to schedule events.
4 SIGALRM causes
5 it to check its queue for events attached to the current second; if
6 one is found, its label is written to stdout. SIGTERM causes it to
7 terminate, printing a list of pending events.
9 This program is intended to be used with the lisp package called
10 timer.el. The first such program was written anonymously in 1990.
11 This version was documented and rewritten for portability by
12 esr@snark.thyrsus.com, Aug 7 1992. */
14 #include <stdio.h>
15 #include <signal.h>
16 #include <errno.h>
17 #include <sys/types.h> /* time_t */
19 #include <../src/config.h>
20 #undef read
22 #ifdef LINUX
23 /* Perhaps this is correct unconditionally. */
24 #undef signal
25 #endif
26 #ifdef _CX_UX
27 /* I agree with the comment above, this probably should be unconditional (it
28 * is already unconditional in a couple of other files in this directory),
29 * but in the spirit of minimizing the effects of my port, I am making it
30 * conditional on _CX_UX.
32 #undef signal
33 #endif
36 extern int errno;
37 extern char *strerror ();
38 extern time_t time ();
41 * The field separator for input. This character shouldn't occur in dates,
42 * and should be printable so event strings are readable by people.
44 #define FS '@'
46 struct event
48 char *token;
49 time_t reply_at;
51 int events_size; /* How many slots have we allocated? */
52 int num_events; /* How many are actually scheduled? */
53 struct event *events; /* events[0 .. num_events-1] are the
54 valid events. */
56 char *pname; /* program name for error messages */
58 /* This buffer is used for reading commands.
59 We make it longer when necessary, but we never free it. */
60 char *buf;
61 /* This is the allocated size of buf. */
62 int buf_size;
64 /* Non-zero means don't handle an alarm now;
65 instead, just set alarm_deferred if an alarm happens.
66 We set this around parts of the program that call malloc and free. */
67 int defer_alarms;
69 /* Non-zero if an alarm came in during the reading of a command. */
70 int alarm_deferred;
72 /* Schedule one event, and arrange an alarm for it.
73 STR is a string of two fields separated by FS.
74 First field is string for get_date, saying when to wake-up.
75 Second field is a token to identify the request. */
77 void
78 schedule (str)
79 char *str;
81 extern time_t get_date ();
82 extern char *strcpy ();
83 time_t now;
84 register char *p;
85 static struct event *ep;
87 /* check entry format */
88 for (p = str; *p && *p != FS; p++)
89 continue;
90 if (!*p)
92 fprintf (stderr, "%s: bad input format: %s\n", pname, str);
93 return;
95 *p++ = 0;
97 /* allocate an event slot */
98 ep = events + num_events;
100 /* If the event array is full, stretch it. After stretching, we know
101 that ep will be pointing to an available event spot. */
102 if (ep == events + events_size)
104 int old_size = events_size;
106 events_size *= 2;
107 events = ((struct event *)
108 realloc (events, events_size * sizeof (struct event)));
109 if (! events)
111 fprintf (stderr, "%s: virtual memory exhausted.\n", pname);
112 /* Since there is so much virtual memory, and running out
113 almost surely means something is very very wrong,
114 it is best to exit rather than continue. */
115 exit (1);
118 while (old_size < events_size)
119 events[old_size++].token = NULL;
122 /* Don't allow users to schedule events in past time. */
123 ep->reply_at = get_date (str, NULL);
124 if (ep->reply_at - time (&now) < 0)
126 fprintf (stderr, "%s: bad time spec: %s%c%s\n", pname, str, FS, p);
127 return;
130 /* save the event description */
131 ep->token = (char *) malloc ((unsigned) strlen (p) + 1);
132 if (! ep->token)
134 fprintf (stderr, "%s: malloc %s: %s%c%s\n",
135 pname, strerror (errno), str, FS, p);
136 return;
139 strcpy (ep->token, p);
140 num_events++;
143 /* Print the notification for the alarmed event just arrived if any,
144 and schedule an alarm for the next event if any. */
146 void
147 notify ()
149 time_t now, tdiff, waitfor = -1;
150 register struct event *ep;
152 /* Inhibit interference with alarms while changing global vars. */
153 defer_alarms = 1;
154 alarm_deferred = 0;
156 now = time ((time_t *) NULL);
158 for (ep = events; ep < events + num_events; ep++)
159 /* Are any events ready to fire? */
160 if (ep->reply_at <= now)
162 fputs (ep->token, stdout);
163 putc ('\n', stdout);
164 fflush (stdout);
165 free (ep->token);
167 /* We now have a hole in the event array; fill it with the last
168 event. */
169 ep->token = events[num_events - 1].token;
170 ep->reply_at = events[num_events - 1].reply_at;
171 num_events--;
173 /* We ought to scan this event again. */
174 ep--;
176 else
178 /* next timeout should be the soonest of any remaining */
179 if ((tdiff = ep->reply_at - now) < waitfor || waitfor < 0)
180 waitfor = (long)tdiff;
183 /* If there are no more events, we needn't bother setting an alarm. */
184 if (num_events > 0)
185 alarm (waitfor);
187 /* Now check if there was another alarm
188 while we were handling an explicit request. */
189 defer_alarms = 0;
190 if (alarm_deferred)
191 notify ();
192 alarm_deferred = 0;
195 /* Read one command from command from standard input
196 and schedule the event for it. */
198 void
199 getevent ()
201 int i;
203 /* In principle the itimer should be disabled on entry to this
204 function, but it really doesn't make any important difference
205 if it isn't. */
207 if (buf == 0)
209 buf_size = 80;
210 buf = (char *) malloc (buf_size);
213 /* Read a line from standard input, expanding buf if it is too short
214 to hold the line. */
215 for (i = 0; ; i++)
217 char c;
218 int nread;
220 if (i >= buf_size)
222 buf_size *= 2;
223 alarm_deferred = 0;
224 defer_alarms = 1;
225 buf = (char *) realloc (buf, buf_size);
226 defer_alarms = 0;
227 if (alarm_deferred)
228 notify ();
229 alarm_deferred = 0;
232 /* Read one character into c. */
233 while (1)
235 nread = read (fileno (stdin), &c, 1);
237 /* Retry after transient error. */
238 if (nread < 0
239 && (1
240 #ifdef EINTR
241 || errno == EINTR
242 #endif
243 #ifdef EAGAIN
244 || errno == EAGAIN
245 #endif
247 continue;
249 /* Report serious errors. */
250 if (nread < 0)
252 perror ("read");
253 exit (1);
256 /* On eof, exit. */
257 if (nread == 0)
258 exit (0);
260 break;
263 if (c == '\n')
265 buf[i] = '\0';
266 break;
269 buf[i] = c;
272 /* Register the event. */
273 alarm_deferred = 0;
274 defer_alarms = 1;
275 schedule (buf);
276 defer_alarms = 0;
277 notify ();
278 alarm_deferred = 0;
281 /* Handle incoming signal SIG. */
283 SIGTYPE
284 sigcatch (sig)
285 int sig;
287 struct event *ep;
289 /* required on older UNIXes; harmless on newer ones */
290 signal (sig, sigcatch);
292 switch (sig)
294 case SIGALRM:
295 if (defer_alarms)
296 alarm_deferred = 1;
297 else
298 notify ();
299 break;
300 case SIGTERM:
301 fprintf (stderr, "Events still queued:\n");
302 for (ep = events; ep < events + num_events; ep++)
303 fprintf (stderr, "%d = %ld @ %s\n",
304 ep - events, ep->reply_at, ep->token);
305 exit (0);
306 break;
310 /*ARGSUSED*/
312 main (argc, argv)
313 int argc;
314 char **argv;
316 for (pname = argv[0] + strlen (argv[0]);
317 *pname != '/' && pname != argv[0];
318 pname--);
319 if (*pname == '/')
320 pname++;
322 events_size = 16;
323 events = ((struct event *) malloc (events_size * sizeof (*events)));
324 num_events = 0;
326 signal (SIGALRM, sigcatch);
327 signal (SIGTERM, sigcatch);
329 /* Loop reading commands from standard input
330 and scheduling alarms accordingly.
331 The alarms are handled asynchronously, while we wait for commands. */
332 while (1)
333 getevent ();
336 #ifndef HAVE_STRERROR
337 char *
338 strerror (errnum)
339 int errnum;
341 extern char *sys_errlist[];
342 extern int sys_nerr;
344 if (errnum >= 0 && errnum < sys_nerr)
345 return sys_errlist[errnum];
346 return (char *) "Unknown error";
349 #endif /* ! HAVE_STRERROR */
351 long *
352 xmalloc (size)
353 int size;
355 register long *val;
357 val = (long *) malloc (size);
359 if (!val && size)
361 fprintf (stderr, "timer: virtual memory exceeded\n");
362 exit (1);
365 return val;
368 /* timer.c ends here */