/***************************************************************************
 *   Copyright (C) 2006 by Torben H. Nielsen                               *
 *   torben@t-hoerup.dk                                                    *
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 *   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.                          *
 *                                                                         *
 *   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.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

/* daemon.[hc] indeholder alle daemon relaterede functioner incl.
 * getConfig();
 * daemonize();
 * writelog();
 */

#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <signal.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "daemon.h"


static const char *months[] = {
	"Jan","Feb","Mar","Apr","May","Jun",
	"Jul","Aug","Sep","Oct","Nov","Dec"
};

// write message to the logfile 
void log_message(char *message)
{
	FILE *logfile;
	char buf[30];
	long n = time(NULL);
	struct tm *now;
	now = localtime(&n);

	sprintf(buf, "%02d:%02d:%02d %s %02d %02d", 
			now->tm_hour, now->tm_min, now->tm_sec,months[now->tm_mon],
			now->tm_mday,now->tm_year % 100);
	
	if (CONFIG->debug) {
		printf("%s: %s\n", buf, message);
		fflush(stdout);
	} else {
		logfile = fopen(CONFIG->logfile, "a");
		if (!logfile) 
			return;
		fprintf(logfile, "%s: %s\n", buf, message);
		fclose(logfile);
	}
}


void signal_handler(int sig)
{
	switch(sig) {
		case SIGHUP:
			log_message("hangup signal catched");
			break;
		case SIGTERM:
			log_message("terminate signal catched...exiting");
			unlink(CONFIG->lock);
			daemon_shutdown(0);
			break;
	}
}


void daemonize()
{	
	int i, lfp;
	char str[10];
	
	if (getppid() == 1) /* already a daemon */
		return;
		
	i=fork();
	
	if (i<0) /* fork error */
		daemon_shutdown(FORK_ERROR);
	if (i>0) /* parent exits */
		daemon_shutdown(0);
	/* child daemon continues */
	
	setsid(); /* obtain a new process group */
	
	for (i=getdtablesize(); i>=0; --i)
		close(i); /*close all descriptors*/
		
	i=open("/dev/null", O_RDWR); /* handle std. io */
	dup(i);
	dup(i);
	
	umask(027); /* set newly created file permissions */
	
	chdir(CONFIG->rundir); /* change running directory*/
	
	//attempt to create lockfile and put a file-lock on it
	lfp=open(CONFIG->lock, O_RDWR|O_CREAT, 0640);
	if (lfp<0) /* can not open */
		daemon_shutdown(CANT_OPEN_LOCK);
	if (lockf(lfp,F_TLOCK,0) < 0) /* can not lock */
		daemon_shutdown(ALREADY_LOCKED);
	
	/* first instance continues */
	sprintf(str, "%d\n", getpid() ); /* record pid to lockfile */
	write(lfp, str, strlen(str) );
	signal(SIGCHLD, SIG_IGN); /* ignore child */
	signal(SIGTSTP, SIG_IGN); /* ignore tty signals */
	signal(SIGTTOU, SIG_IGN);
	signal(SIGTTIN, SIG_IGN);
	signal(SIGHUP, signal_handler); /* catch hangup signal */
	signal(SIGTERM, signal_handler); /* catch kill signal */	
	log_message("downloadd started ...");
}


void read_config_file(char *configfile) {
	char buf[120];
	FILE *input = 0;
	int pos;
	char *cptr;
	
	// first populate config with default values
	strcpy(CONFIG->logfile, "/tmp/downloadd.log");
	strcpy(CONFIG->lock, "/tmp/downloadd.lock");
	strcpy(CONFIG->rundir, "/tmp");
	
	strcpy(CONFIG->dbuser, "myuser");
	strcpy(CONFIG->dbpass, "mypass");
	strcpy(CONFIG->dbhost, "localhost");
	strcpy(CONFIG->dbname, "downloadd");
	CONFIG->dbport = 3306;
	
	// first try to open the file
	if (configfile && strlen(configfile) >0) {
		input = fopen(configfile, "r");
		
		if (input) {
			while (!feof(input)) {
				fgets(buf, 120, input);
				
				pos = strlen(buf);
				if (strlen(buf)>0 && buf[pos-1] == '\n')
					buf[pos-1] = 0; //ignore trailing newline
				
				if (strlen(buf)==0 || buf[0] == '#' || buf[0] == ';')
					continue;
				cptr = strchr(buf, ' ');
				cptr++;
				if(strncmp(buf,"logfile ",8)==0) {
					strcpy(CONFIG->logfile, cptr);
				} else if (strncmp(buf,"lock ",5)==0) {
					strcpy(CONFIG->lock, cptr);
				} else if (strncmp(buf, "rundir ",7)==0) {
					strcpy(CONFIG->rundir, cptr);
				} else if (strncmp(buf, "dbuser ",7)==0) {
					strcpy(CONFIG->dbuser,cptr);
				} else if (strncmp(buf, "dbpass ",7)==0) {
					strcpy(CONFIG->dbpass,cptr);
				} else if (strncmp(buf, "dbhost ",7)==0) {
					strcpy(CONFIG->dbhost,cptr);
				} else if (strncmp(buf, "dbname ",7)==0) {
					strcpy(CONFIG->dbname,cptr);
				} else if (strncmp(buf, "dbport ",7)==0) {
					CONFIG->dbport = atoi(cptr);
				} else {
					printf("unknown config directive: %s\n", buf);
					fflush(stdout);
				}
				//make the buffer look empty
				buf[0] = 0;
			}
		} else {
			sprintf(buf,"Could not open config file %s, using default values.", configfile);
			log_message(buf);
		}
	} else {
		log_message( "No config file specified. Using default values.");
	}
	
	//at the end we should at least validate lock, logfile & rundir
}

void daemon_shutdown(int errorlevel) {
	log_message("Shutting down...");
	exit(errorlevel);
}