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#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <errno.h>
#include <string.h>
char *pidfile;
char *get_cronolog(void) {
int len = 0;
char *path, *tmp = NULL;
struct stat st;
path = strtok(getenv("PATH"), ":");
while(path != NULL) {
len = (strlen(path) + strlen("/cronolog") + 1);
tmp = (char *)malloc(len);
snprintf(tmp, len, "%s%s", path, "/cronolog");
if(stat(tmp, &st) == -1) {
if(errno == ENOENT) {
free(tmp);
path = strtok(NULL, ":");
continue;
}
fprintf(stderr, "stat(): Error: %s\n", strerror(errno));
free(tmp);
return NULL;
}
if(st.st_mode & S_IFREG)
return tmp;
else {
free(tmp);
return NULL;
}
}
if(tmp != NULL)
free(tmp);
return NULL;
}
void die(int sig) {
/* kill off children */
kill(0, SIGTERM);
/* remove pid file, quit */
unlink(pidfile);
exit(0);
}
struct sigaction sigdie = { .sa_handler = die };
int main(int argc, char *argv[]) {
time_t t = 0;
pid_t pid = 0;
int fd, pidfd, pidlen = 16;
char *fifo, *log, *cronolog, pidstr[16];
if (argc != 4) {
fprintf(stderr, "Usage: %s /path/to/pidfile /path/to/fifo"
" /path/to/logs/%%Y%%m%%d.log\n", argv[0]);
exit(1);
}
pidfile = argv[1];
fifo = argv[2];
log = argv[3];
cronolog = get_cronolog();
if(cronolog == NULL) {
fprintf(stderr, "cronolog not found in PATH\n");
exit(1);
}
/* Test for fifo access, leave open for use */
/* O_NONBLOCK allows us to fork into the background */
fd = open(fifo, O_RDONLY|O_NONBLOCK);
if (fd == -1) {
fprintf(stderr, "Cannot open fifo %s: %s\n", fifo, strerror(errno));
free(cronolog);
exit(1);
}
pid = fork();
if (pid == 0) {
/* CHILD 0 */
/* Record pid to pidfile */
pidfd = open(pidfile, O_WRONLY|O_CREAT|O_EXCL, 0644);
if (pidfd == -1) {
fprintf(stderr, "Cannot create and open pid file %s: %s\n",
pidfile, strerror(errno));
free(cronolog);
exit(1);
} else {
pidlen = snprintf(pidstr, pidlen, "%d\n", getpid());
if(write(pidfd, pidstr, pidlen) == -1) {
fprintf(stderr, "Cannot write pid file %s: %s\n", pidfile, strerror(errno));
free(cronolog);
exit(1);
}
close(pidfd);
}
/* close shell output */
close(0);
close(1);
close(2);
/* set a process group for easy cleanup */
setpgrp();
sigaction(SIGTERM, &sigdie, NULL);
/* keep the cronolog process open */
while (1) {
t = time(NULL);
pid = fork();
if (pid == 0) {
/* CHILD 1 */
/* replace stdin with fifo */
dup2(fd, 0);
/* unset O_NONBLOCK */
fcntl(0, F_SETFL, 0);
/* exec cronolog */
execl(cronolog, cronolog, log, (char *) 0);
/* filure! give up on life */
free(cronolog);
exit(1);
} else {
/* PARENT 1 */
/* watch child 1 */
waitpid(pid, NULL, 0);
if (time(NULL) - t < 2) {
/* restarting too fast, wait 10 seconds */
sleep(10);
}
}
}
}
/* PARENT 0 exits */
close(fd);
free(cronolog);
return 0;
}
/* vim: set ts=4 sw=4 tw=80: */
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