cronie/anacron/lock.c

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/*
Anacron - run commands periodically
Copyright (C) 1998 Itai Tzur <itzur@actcom.co.il>
Copyright (C) 1999 Sean 'Shaleh' Perry <shaleh@debian.org>
Copyirght (C) 2004 Pascal Hakim <pasc@redellipse.net>
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This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
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This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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The GNU General Public License can also be found in the file
`COPYING' that comes with the Anacron source distribution.
*/
/* Lock and timestamp management
*/
#include <stdio.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include "global.h"
#include "gregor.h"
static void
open_tsfile(job_rec *jr)
/* Open the timestamp file for job jr */
{
jr->timestamp_fd = open(jr->ident, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
if (jr->timestamp_fd == -1)
die_e("Can't open timestamp file for job %s", jr->ident);
fcntl(jr->timestamp_fd, F_SETFD, 1); /* set close-on-exec flag */
/* We want to own this file, and set its mode to 0600. This is necessary
* in order to prevent other users from putting locks on it. */
if (fchown(jr->timestamp_fd, getuid(), getgid()))
die_e("Can't chown timestamp file %s", jr->ident);
if (fchmod(jr->timestamp_fd, S_IRUSR | S_IWUSR))
die_e("Can't chmod timestamp file %s", jr->ident);
}
static int
lock_file(int fd)
/* Attempt to put an exclusive fcntl() lock on file "fd"
* Return 1 on success, 0 on failure.
*/
{
int r;
struct flock sfl;
sfl.l_type = F_WRLCK;
sfl.l_start = 0;
sfl.l_whence = SEEK_SET;
sfl.l_len = 0; /* we lock all the file */
errno = 0;
r = fcntl(fd, F_SETLK, &sfl);
if (r != -1) return 1;
if (errno != EACCES && errno != EAGAIN)
die_e("fcntl() error");
return 0;
}
int
consider_job(job_rec *jr)
/* Check the timestamp of the job. If "its time has come", lock the job
* and return 1, if it's too early, or we can't get the lock, return 0.
*/
{
char timestamp[9];
int ts_year, ts_month, ts_day, dn;
ssize_t b;
open_tsfile(jr);
/* read timestamp */
b = read(jr->timestamp_fd, timestamp, 8);
if (b == -1) die_e("Error reading timestamp file %s", jr->ident);
timestamp[8] = 0;
/* is it too early? */
if (!force && b == 8)
{
int day_delta;
time_t jobtime;
struct tm *t;
if (sscanf(timestamp, "%4d%2d%2d", &ts_year, &ts_month, &ts_day) == 3)
dn = day_num(ts_year, ts_month, ts_day);
else
dn = 0;
day_delta = day_now - dn;
/*
* if day_delta is negative, we assume there was a clock skew
* and re-run any affected jobs
* otherwise we check if the job's time has come
*/
if (day_delta >= 0 && day_delta < jr->period)
{
/* yes, skip job */
xclose(jr->timestamp_fd);
return 0;
}
/*
* Check to see if it's a named period, in which case we need
* to figure it out.
*/
if (jr->named_period)
{
int period = 0, bypass = 0;
switch (jr->named_period)
{
case 1: /* monthly */
period = days_last_month ();
bypass = days_this_month ();
break;
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case 2: /* yearly, annually */
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period = days_last_year ();
bypass = days_this_year ();
break;
case 3: /* daily */
period = 1;
bypass = 1;
break;
case 4: /* weekly */
period = 7;
bypass = 7;
break;
default:
die ("Unknown named period for %s (%d)", jr->ident, jr->named_period);
}
printf ("Checking against %d with %d\n", day_delta, period);
if (day_delta < period && day_delta != bypass)
{
/* Job is still too young */
xclose (jr->timestamp_fd);
return 0;
}
}
jobtime = start_sec + jr->delay * 60;
t = localtime(&jobtime);
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if (!now && preferred_hour != -1 && t->tm_hour != preferred_hour) {
Debug(("The job's %s preferred hour %d was missed, skipping the job.", jr->ident, preferred_hour));
xclose (jr->timestamp_fd);
return 0;
}
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if (!now && range_start != -1 && range_stop != -1 &&
(t->tm_hour < range_start || t->tm_hour >= range_stop))
{
Debug(("The job `%s' falls out of the %02d:00-%02d:00 hours range, skipping.",
jr->ident, range_start, range_stop));
xclose (jr->timestamp_fd);
return 0;
}
}
/* no! try to grab the lock */
if (lock_file(jr->timestamp_fd)) return 1; /* success */
/* didn't get lock */
xclose(jr->timestamp_fd);
explain("Job `%s' locked by another anacron - skipping", jr->ident);
return 0;
}
void
unlock(job_rec *jr)
{
xclose(jr->timestamp_fd);
}
void
update_timestamp(job_rec *jr)
/* We write the date "now". "Now" can be either the time when anacron
* started, or the time when the job finished.
* I'm not quite sure which is more "right", but I've decided on the first
* option.
* Note that this is not the way it was with anacron 1.0.3 to 1.0.7.
*/
{
char stamp[10];
snprintf(stamp, 10, "%04d%02d%02d\n", year, month, day_of_month);
if (lseek(jr->timestamp_fd, 0, SEEK_SET))
die_e("Can't lseek timestamp file for job %s", jr->ident);
if (write(jr->timestamp_fd, stamp, 9) != 9)
die_e("Can't write timestamp file for job %s", jr->ident);
if (ftruncate(jr->timestamp_fd, 9))
die_e("ftruncate error");
}
void
fake_job(job_rec *jr)
/* We don't bother with any locking here. There's no point. */
{
open_tsfile(jr);
update_timestamp(jr);
xclose(jr->timestamp_fd);
}