/*
Copyright (c) 2007-2010, Gentoo Foundation
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/

#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>

#define VERSION "1.1.1"

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]);
		fprintf(stderr, "fifo-cronolog version: %s\n", VERSION);
		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: */