minix3/commands/cron/cron.c

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2020-02-21 00:59:27 +05:30
/* cron 1.4 - clock daemon Author: Kees J. Bot
* 7 Dec 1996
*/
#define nil ((void*)0)
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <limits.h>
#include <dirent.h>
#include <time.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <pwd.h>
#include <grp.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include "misc.h"
#include "tab.h"
#if __minix && !__minix_vmd
#define initgroups(name, gid) (0)
#endif
static volatile int busy; /* Set when something is afoot, don't sleep! */
static volatile int need_reload;/* Set if table reload required. */
static volatile int need_quit; /* Set if cron must exit. */
static volatile int debug; /* Debug level. */
static void run_job(cronjob_t *job)
/* Execute a cron job. Register its pid in the job structure. If a job's
* crontab has an owner then its output is mailed to that owner, otherwise
* no special provisions are made, so the output will go where cron's output
* goes. This keeps root's mailbox from filling up.
*/
{
pid_t pid;
int need_mailer;
int mailfd[2], errfd[2];
struct passwd *pw;
crontab_t *tab= job->tab;
need_mailer= (tab->user != nil);
if (job->atjob) {
struct stat st;
need_mailer= 1;
if (rename(tab->file, tab->data) < 0) {
if (errno == ENOENT) {
/* Normal error, job deleted. */
need_reload= 1;
} else {
/* Bad error, halt processing AT jobs. */
log(LOG_CRIT, "Can't rename %s: %s\n",
tab->file, strerror(errno));
tab_reschedule(job);
}
return;
}
/* Will need to determine the next AT job. */
need_reload= 1;
if (stat(tab->data, &st) < 0) {
log(LOG_ERR, "Can't stat %s: %s\n",
tab->data, strerror(errno));
tab_reschedule(job);
return;
}
if ((pw= getpwuid(st.st_uid)) == nil) {
log(LOG_ERR, "Unknown owner for uid %lu of AT job %s\n",
(unsigned long) st.st_uid, job->cmd);
tab_reschedule(job);
return;
}
} else {
pw= nil;
if (job->user != nil && (pw= getpwnam(job->user)) == nil) {
log(LOG_ERR, "%s: Unknown user\n", job->user);
tab_reschedule(job);
return;
}
}
if (need_mailer) {
errfd[0]= -1;
if (pipe(errfd) < 0 || pipe(mailfd) < 0) {
log(LOG_ERR, "pipe() call failed: %s\n",
strerror(errno));
if (errfd[0] != -1) {
close(errfd[0]);
close(errfd[1]);
}
tab_reschedule(job);
return;
}
(void) fcntl(errfd[1], F_SETFD,
fcntl(errfd[1], F_GETFD) | FD_CLOEXEC);
if ((pid= fork()) == -1) {
log(LOG_ERR, "fork() call failed: %s\n",
strerror(errno));
close(errfd[0]);
close(errfd[1]);
close(mailfd[0]);
close(mailfd[1]);
tab_reschedule(job);
return;
}
if (pid == 0) {
/* Child that is to be the mailer. */
char subject[70+20], *ps;
close(errfd[0]);
close(mailfd[1]);
if (mailfd[0] != 0) {
dup2(mailfd[0], 0);
close(mailfd[0]);
}
memset(subject, 0, sizeof(subject));
sprintf(subject,
"Output from your %s job: %.50s",
job->atjob ? "AT" : "cron",
job->cmd);
if (subject[70] != 0) {
strcpy(subject+70-3, "...");
}
for (ps= subject; *ps != 0; ps++) {
if (*ps == '\n') *ps= '%';
}
execl("/usr/bin/mail", "mail", "-s", subject,
pw->pw_name, (char *) nil);
write(errfd[1], &errno, sizeof(errno));
_exit(1);
}
close(mailfd[0]);
close(errfd[1]);
if (read(errfd[0], &errno, sizeof(errno)) > 0) {
log(LOG_ERR, "can't execute /usr/bin/mail: %s\n",
strerror(errno));
close(errfd[0]);
close(mailfd[1]);
tab_reschedule(job);
return;
}
close(errfd[0]);
}
if (pipe(errfd) < 0) {
log(LOG_ERR, "pipe() call failed: %s\n", strerror(errno));
if (need_mailer) close(mailfd[1]);
tab_reschedule(job);
return;
}
(void) fcntl(errfd[1], F_SETFD, fcntl(errfd[1], F_GETFD) | FD_CLOEXEC);
if ((pid= fork()) == -1) {
log(LOG_ERR, "fork() call failed: %s\n", strerror(errno));
close(errfd[0]);
close(errfd[1]);
if (need_mailer) close(mailfd[1]);
tab_reschedule(job);
return;
}
if (pid == 0) {
/* Child that is to be the cron job. */
close(errfd[0]);
if (need_mailer) {
if (mailfd[1] != 1) {
dup2(mailfd[1], 1);
close(mailfd[1]);
}
dup2(1, 2);
}
if (pw != nil) {
/* Change id to the owner of the job. */
initgroups(pw->pw_name, pw->pw_gid);
setgid(pw->pw_gid);
setuid(pw->pw_uid);
chdir(pw->pw_dir);
if (setenv("USER", pw->pw_name, 1) < 0) goto bad;
if (setenv("LOGNAME", pw->pw_name, 1) < 0) goto bad;
if (setenv("HOME", pw->pw_dir, 1) < 0) goto bad;
if (setenv("SHELL", pw->pw_shell[0] == 0 ? "/bin/sh"
: pw->pw_shell, 1) < 0) goto bad;
}
if (job->atjob) {
execl("/bin/sh", "sh", tab->data, (char *) nil);
} else {
execl("/bin/sh", "sh", "-c", job->cmd, (char *) nil);
}
bad:
write(errfd[1], &errno, sizeof(errno));
_exit(1);
}
if (need_mailer) close(mailfd[1]);
close(errfd[1]);
if (read(errfd[0], &errno, sizeof(errno)) > 0) {
log(LOG_ERR, "can't execute /bin/sh: %s\n", strerror(errno));
close(errfd[0]);
tab_reschedule(job);
return;
}
close(errfd[0]);
job->pid= pid;
if (debug >= 1) fprintf(stderr, "executing >%s<, pid = %ld\n",
job->cmd, (long) job->pid);
}
static void load_crontabs(void)
/* Load all the crontabs we like to run. We didn't bother to make a list in
* an array or something, this is too system specific to make nice.
*/
{
DIR *spool;
#if __minix_vmd
FILE *pkgs;
#endif
tab_parse("/usr/lib/crontab", nil);
tab_parse("/usr/local/lib/crontab", nil);
tab_parse("/var/lib/crontab", nil);
#if __minix_vmd
if ((pkgs= fopen("/usr/lib/packages", "r")) != nil) {
char name[NAME_MAX+1];
char *np;
int c;
char tab[sizeof("/var/opt//lib/crontab") + NAME_MAX];
while ((c= fgetc(pkgs)) != EOF) {
np= name;
while (c != EOF && c != '/' && c != '\n') {
if (np < name+NAME_MAX) *np++ = c;
c= fgetc(pkgs);
}
*np= 0;
while (c != EOF && c != '\n') c= fgetc(pkgs);
if (name[0] == 0) continue; /* ? */
strcpy(tab, "/var/opt/");
strcat(tab, name);
strcat(tab, "/lib/crontab");
tab_parse(tab, nil);
}
if (ferror(pkgs)) {
log(LOG_CRIT, "/usr/lib/packages: %s\n",
strerror(errno));
}
fclose(pkgs);
} else {
if (errno != ENOENT) {
log(LOG_ERR, "/usr/lib/packages: %s\n",
strerror(errno));
}
}
#endif /* Minix-vmd */
if ((spool= opendir("/usr/spool/crontabs")) != nil) {
struct dirent *entry;
char tab[sizeof("/usr/spool/crontabs/") + NAME_MAX];
while ((entry= readdir(spool)) != nil) {
if (entry->d_name[0] == '.') continue;
strcpy(tab, "/usr/spool/crontabs/");
strcat(tab, entry->d_name);
tab_parse(tab, entry->d_name);
}
closedir(spool);
}
/* Find the first to be executed AT job. */
tab_find_atjob("/usr/spool/at");
tab_purge();
if (debug >= 2) {
tab_print(stderr);
fprintf(stderr, "%lu memory chunks in use\n",
(unsigned long) alloc_count);
}
}
static void handler(int sig)
{
switch (sig) {
case SIGHUP:
need_reload= 1;
break;
case SIGINT:
case SIGTERM:
need_quit= 1;
break;
case SIGUSR1:
debug++;
break;
case SIGUSR2:
debug= 0;
break;
}
alarm(1); /* A signal may come just before a blocking call. */
busy= 1;
}
static void usage(void)
{
fprintf(stderr, "Usage: %s [-d[#]]\n", prog_name);
exit(1);
}
int main(int argc, char **argv)
{
int i;
struct sigaction sa, osa;
FILE *pf;
int r;
prog_name= strrchr(argv[0], '/');
if (prog_name == nil) prog_name= argv[0]; else prog_name++;
i= 1;
while (i < argc && argv[i][0] == '-') {
char *opt= argv[i++] + 1;
if (opt[0] == '-' && opt[1] == 0) break; /* -- */
while (*opt != 0) switch (*opt++) {
case 'd':
if (*opt == 0) {
debug= 1;
} else {
debug= strtoul(opt, &opt, 10);
if (*opt != 0) usage();
}
break;
default:
usage();
}
}
if (i != argc) usage();
selectlog(SYSLOG);
openlog(prog_name, LOG_PID, LOG_DAEMON);
setlogmask(LOG_UPTO(LOG_INFO));
/* Save process id. */
if ((pf= fopen(PIDFILE, "w")) == NULL) {
fprintf(stderr, "%s: %s\n", PIDFILE, strerror(errno));
exit(1);
}
fprintf(pf, "%d\n", getpid());
if (ferror(pf) || fclose(pf) == EOF) {
fprintf(stderr, "%s: %s\n", PIDFILE, strerror(errno));
exit(1);
}
sigemptyset(&sa.sa_mask);
sa.sa_flags= 0;
sa.sa_handler= handler;
/* Hangup: Reload crontab files. */
sigaction(SIGHUP, &sa, nil);
/* User signal 1 & 2: Raise or reset debug level. */
sigaction(SIGUSR1, &sa, nil);
sigaction(SIGUSR2, &sa, nil);
/* Interrupt and Terminate: Cleanup and exit. */
if (sigaction(SIGINT, nil, &osa) == 0 && osa.sa_handler != SIG_IGN) {
sigaction(SIGINT, &sa, nil);
}
if (sigaction(SIGTERM, nil, &osa) == 0 && osa.sa_handler != SIG_IGN) {
sigaction(SIGTERM, &sa, nil);
}
/* Alarm: Wake up and run a job. */
sigaction(SIGALRM, &sa, nil);
/* Initialize current time and time next to do something. */
time(&now);
next= NEVER;
/* Table load required first time. */
need_reload= 1;
do {
if (need_reload) {
need_reload= 0;
load_crontabs();
busy= 1;
}
/* Run jobs whose time has come. */
if (next <= now) {
cronjob_t *job;
if ((job= tab_nextjob()) != nil) run_job(job);
busy= 1;
}
if (busy) {
/* Did a job finish? */
r= waitpid(-1, nil, WNOHANG);
busy= 0;
} else {
/* Sleep until the next job must be started. */
if (next == NEVER) {
alarm(0);
} else {
#if __minix_vmd
struct timeval tvnext;
tvnext.tv_sec= next;
tvnext.tv_usec= 0;
sysutime(UTIME_SETALARM, &tvnext);
#else
alarm((next - now) > INT_MAX
? INT_MAX : (next - now));
#endif
}
if (debug >= 1) fprintf(stderr, "%s: sleep until %s",
prog_name, ctime(&next));
closelog(); /* Don't keep resources open. */
/* Wait for a job to exit or a timeout. */
r= waitpid(-1, nil, 0);
if (r == -1 && errno == ECHILD) pause();
alarm(0);
time(&now);
}
if (r > 0) {
/* A job has finished, reschedule it. */
if (debug >= 1) fprintf(stderr, "pid %d has exited\n",
r);
tab_reap_job((pid_t) r);
busy= 1;
}
} while (!need_quit);
/* Remove the pid file to signal that cron is gone. */
unlink(PIDFILE);
return 0;
}
/*
* $PchId: cron.c,v 1.4 2000/07/17 19:00:35 philip Exp $
*/