daemon.c

#include "deamon.h"

int
daemonize(const char* name, const char* path, const char* outfile, const char* errfile, const char* infile )
{
	if(!path) 
	{ 
		path="/"; 
	}
	if(!name) 
	{ 
		name="medaemon"; 
	}
	if(!infile) 
	{ 
		infile="/dev/null"; 
	}
	if(!outfile) 
	{ 
		outfile="/dev/null"; 
	}
	if(!errfile) 
	{ 
		errfile="/dev/null"; 
	}
	printf("%s %s %s %s\n",name,path,outfile,infile);
	pid_t child;
	//fork, detach from process group leader
	if( (child=fork())<0 ) 
	{ 						//failed fork
		fprintf(stderr,"error: failed fork\n");
		exit(EXIT_FAILURE);
	}
	if (child>0) 
	{ 						//parent
		exit(EXIT_SUCCESS);
	}
	if( setsid()<0 ) 
	{ 						//failed to become session leader
		fprintf(stderr,"error: failed setsid\n");
		exit(EXIT_FAILURE);
	}

	//catch/ignore signals
	signal(SIGCHLD,SIG_IGN);
	signal(SIGHUP,SIG_IGN);

	//fork second time
	if ( (child=fork())<0 ) 
	{ 					//failed fork
		fprintf(stderr,"error: failed fork\n");
		exit(EXIT_FAILURE);
	}
	if( child>0 ) 
	{ 					//parent
		exit(EXIT_SUCCESS);
	}

	//new file permissions
	umask(0);
	//change to path directory
	chdir(path);

	//Close all open file descriptors
	int fd;
	for( fd=sysconf(_SC_OPEN_MAX); fd>0; --fd )
	{
		close(fd);
	}

	//reopen stdin, stdout, stderr
	stdin=fopen(infile,"r");   		//fd=0
	stdout=fopen(outfile,"w+");  		//fd=1
	stderr=fopen(errfile,"w+");  		//fd=2

	//open syslog
	openlog(name,LOG_PID,LOG_DAEMON);
	return(0);
}