2.11BSD/src/usr.sbin/cron/cron.c
/* Copyright 1988,1990,1993,1994 by Paul Vixie
* All rights reserved
*
* Distribute freely, except: don't remove my name from the source or
* documentation (don't take credit for my work), mark your changes (don't
* get me blamed for your possible bugs), don't alter or remove this
* notice. May be sold if buildable source is provided to buyer. No
* warrantee of any kind, express or implied, is included with this
* software; use at your own risk, responsibility for damages (if any) to
* anyone resulting from the use of this software rests entirely with the
* user.
*
* Send bug reports, bug fixes, enhancements, requests, flames, etc., and
* I'll try to keep a version up to date. I can be reached as follows:
* Paul Vixie <paul@vix.com> uunet!decwrl!vixie!paul
*/
#if !defined(lint) && defined(DOSCCS)
static char sccsid[] = "@(#)cron.c 2.11.1 (2.11BSD) 1999/08/05";
#endif
#define MAIN_PROGRAM
#include "cron.h"
#include <sys/signal.h>
#include <sys/time.h>
static void usage __P((void)),
run_reboot_jobs __P((cron_db *)),
cron_tick __P((cron_db *)),
cron_sync __P((void)),
cron_sleep __P((void)),
sigchld_handler __P((int)),
sighup_handler __P((int)),
parse_args __P((int c, char *v[]));
static void
usage() {
fprintf(stderr, "usage: %s [-x debugflag[,...]]\n", ProgramName);
exit(ERROR_EXIT);
}
int
main(argc, argv)
int argc;
char *argv[];
{
cron_db database;
ProgramName = argv[0];
setlinebuf(stdout);
setlinebuf(stderr);
parse_args(argc, argv);
(void) signal(SIGCHLD, sigchld_handler);
(void) signal(SIGHUP, sighup_handler);
acquire_daemonlock(0);
set_cron_uid();
set_cron_cwd();
setenv("PATH", _PATH_DEFPATH, 1);
/* if there are no debug flags turned on, fork as a daemon should.
*/
# if DEBUGGING
if (DebugFlags) {
# else
if (0) {
# endif
(void) fprintf(stderr, "[%d] cron started\n", getpid());
} else {
switch (fork()) {
case -1:
log_it("CRON",getpid(),"DEATH","can't fork");
exit(0);
break;
case 0:
/* child process */
log_it("CRON",getpid(),"STARTUP","fork ok");
(void) setsid();
break;
default:
/* parent process should just die */
_exit(0);
}
}
acquire_daemonlock(0);
database.head = NULL;
database.tail = NULL;
database.mtime = (time_t) 0;
load_database(&database);
run_reboot_jobs(&database);
cron_sync();
while (TRUE) {
# if DEBUGGING
if (!(DebugFlags & DTEST))
# endif /*DEBUGGING*/
cron_sleep();
load_database(&database);
/* do this iteration
*/
cron_tick(&database);
/* sleep 1 minute
*/
TargetTime += 60;
}
}
static void
run_reboot_jobs(db)
cron_db *db;
{
register user *u;
register entry *e;
for (u = db->head; u != NULL; u = u->next) {
for (e = u->crontab; e != NULL; e = e->next) {
if (e->flags & WHEN_REBOOT) {
job_add(e, u);
}
}
}
(void) job_runqueue();
}
static void
cron_tick(db)
cron_db *db;
{
register struct tm *tm = localtime(&TargetTime);
register int minute, hour, dom, month, dow;
register user *u;
register entry *e;
/* make 0-based values out of these so we can use them as indicies
*/
minute = tm->tm_min -FIRST_MINUTE;
hour = tm->tm_hour -FIRST_HOUR;
dom = tm->tm_mday -FIRST_DOM;
month = tm->tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
dow = tm->tm_wday -FIRST_DOW;
Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d)\n",
getpid(), minute, hour, dom, month, dow))
/* the dom/dow situation is odd. '* * 1,15 * Sun' will run on the
* first and fifteenth AND every Sunday; '* * * * Sun' will run *only*
* on Sundays; '* * 1,15 * *' will run *only* the 1st and 15th. this
* is why we keep 'e->dow_star' and 'e->dom_star'. yes, it's bizarre.
* like many bizarre things, it's the standard.
*/
for (u = db->head; u != NULL; u = u->next) {
for (e = u->crontab; e != NULL; e = e->next) {
Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
env_get("LOGNAME", e->envp),
e->uid, e->gid, e->cmd))
if (bit_test(e->minute, minute)
&& bit_test(e->hour, hour)
&& bit_test(e->month, month)
&& ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
? (bit_test(e->dow,dow) && bit_test(e->dom,dom))
: (bit_test(e->dow,dow) || bit_test(e->dom,dom))
)
) {
job_add(e, u);
}
}
}
}
/* the task here is to figure out how long it's going to be until :00 of the
* following minute and initialize TargetTime to this value. TargetTime
* will subsequently slide 60 seconds at a time, with correction applied
* implicitly in cron_sleep(). it would be nice to let cron execute in
* the "current minute" before going to sleep, but by restarting cron you
* could then get it to execute a given minute's jobs more than once.
* instead we have the chance of missing a minute's jobs completely, but
* that's something sysadmin's know to expect what with crashing computers..
*/
static void
cron_sync() {
register struct tm *tm;
TargetTime = time((time_t*)0);
tm = localtime(&TargetTime);
TargetTime += (60 - tm->tm_sec);
}
static void
cron_sleep() {
register int seconds_to_wait;
do {
seconds_to_wait = (int) (TargetTime - time((time_t*)0));
Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
getpid(), TargetTime, seconds_to_wait))
/* if we intend to sleep, this means that it's finally
* time to empty the job queue (execute it).
*
* if we run any jobs, we'll probably screw up our timing,
* so go recompute.
*
* note that we depend here on the left-to-right nature
* of &&, and the short-circuiting.
*/
} while (seconds_to_wait > 0 && job_runqueue());
while (seconds_to_wait > 0) {
Debug(DSCH, ("[%d] sleeping for %d seconds\n",
getpid(), seconds_to_wait))
seconds_to_wait = (int) sleep((unsigned int) seconds_to_wait);
}
}
static void
sigchld_handler(x) {
WAIT_T waiter;
PID_T pid;
for (;;) {
pid = waitpid(-1, &waiter, WNOHANG);
switch (pid) {
case -1:
Debug(DPROC,
("[%d] sigchld...no children\n", getpid()))
return;
case 0:
Debug(DPROC,
("[%d] sigchld...no dead kids\n", getpid()))
return;
default:
Debug(DPROC,
("[%d] sigchld...pid #%d died, stat=%d\n",
getpid(), pid, WEXITSTATUS(waiter)))
}
}
}
static void
sighup_handler(x) {
log_close();
}
static void
parse_args(argc, argv)
int argc;
char *argv[];
{
int argch;
while (EOF != (argch = getopt(argc, argv, "x:"))) {
switch (argch) {
default:
usage();
case 'x':
if (!set_debug_flags(optarg))
usage();
break;
}
}
}