daemonize/daemonize.c - cloudstack - Git at Google

 /*
 UNIX daemonizer.  Daemonizes any non-interactive console program and watches over it.
 Whenever a signal is sent to this process, it halts the daemonized process as well.

 To compile:	cc -o daemonize daemonize.c
 Usage:		./daemonize -?
 Users of this:	catalina initscript
 */

 #include <stdio.h>
 #include <fcntl.h>
 #include <signal.h>
 #include <unistd.h>
 #include <syslog.h>
 #include <string.h>
 #include <stdlib.h>
 #include <getopt.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <errno.h>
 #include <pwd.h>

 #define RUNNING_DIR	"/"
 #define PIDFILE		"/var/run/daemonize.pid"
 #define VARLOGFILE 	"/var/log/daemon.log"
 #define PROGNAME	"daemonized"
 #define DEFAULTUSER	"root"

 char * pidfile = PIDFILE;
 char * varlogfile = VARLOGFILE;
 char * progname = PROGNAME;
 char * user = PROGNAME;

 void initialize_syslog(const char*pn) {
 	openlog(pn,LOG_PID,LOG_DAEMON);
 	syslog(LOG_INFO, "syslog connection opened");
 }

 void cleanup_syslog() {
 	syslog(LOG_INFO, "syslog connection closed");
 	closelog();
 }

 int killed = 0;
 int killsignal = 0;
 int pidfile_fd;
 int varlogfile_fd;
 int uid = 0; int gid = 0;
 struct passwd *creds;

 void signal_handler(sig)
 int sig;
 {
 	killsignal = sig;
 	switch(sig) {
 	case SIGCHLD:
 		syslog(LOG_INFO,"sigchild signal caught");
 		break;
 	case SIGHUP:
 		syslog(LOG_INFO,"hangup signal caught");
 		killed = 1;
 		break;
 	case SIGTERM:
 		syslog(LOG_INFO,"terminate signal caught");
 		killed = 1;
 		break;
 	case SIGINT:
 		syslog(LOG_INFO,"keyboard interrupt signal caught");
 		killed = 1;
 		break;
 	}
 }

 int daemonize(const char*prog_name)
 {

 	char str[10];
 	int i;
 	int bufsize=1024; char *buf = malloc(1024);

 	umask( S_IWGRP | S_IROTH | S_IWOTH ); /* set newly created file permissions */

 	/* test logfile */
 	varlogfile_fd=open(varlogfile,O_RDWR|O_CREAT|O_APPEND,0666);
 	if (varlogfile_fd == -1) {
 		snprintf(buf,bufsize,"Could not open output file %s -- exiting",varlogfile); perror(buf);
 		return 1; /* exitvalue */
 	}
 	if (uid != 0) {
 		chown(varlogfile,uid,gid);
 	}
 	close(varlogfile_fd);
 	pidfile_fd=open(pidfile,O_RDWR|O_CREAT,0666);
 	if (pidfile_fd<0) {
 		snprintf(buf,bufsize,"The PID file %s cannot be opened -- exiting",pidfile); perror(buf);
 		return 2; /* exitvalue */
 	}
 	if (lockf(pidfile_fd,F_TEST,0)==1) {
 		snprintf(buf,bufsize,"A daemon is already running (cannot lock PID file %s) -- exiting",pidfile); perror(buf);
 		return 3; /* exitvalue */
 	}
 	close(pidfile_fd);

 	if(getppid()==1) return 0; /* already a daemon */
 	i=fork();
 	if (i < 0) return 4; /* exitvalue */ /* fork error */
 	if (i > 0) exit(0); /* parent exits */

 	/* child (daemon) continues */
 	setsid(); /* obtain a new process group */

 	chdir(RUNNING_DIR); /* change running directory */

 	/* close FDs and reopen to logfile */
 	for (i=getdtablesize();i>=0;--i) close(i); /* close all descriptors */
 	varlogfile_fd=open(varlogfile,O_RDWR|O_APPEND,0666); dup(varlogfile_fd); dup(varlogfile_fd); /* handle standart I/O */
 	initialize_syslog(prog_name); /* set up syslog */

 	/* PID file */
 	pidfile_fd=open(pidfile,O_RDWR|O_CREAT,0666);
 	if (pidfile_fd<0) {
 		syslog(LOG_ERR,"The PID file %s cannot be opened (%m) -- exiting",pidfile);
 		return 2; /* exitvalue */
 	}
 	if (lockf(pidfile_fd,F_TLOCK,0)<0) {
 		syslog(LOG_ERR,"A daemon is already running -- cannot lock PID file %s (%m) -- exiting",pidfile);
 		return 3; /* exitvalue */
 	}

 	/* first instance continues */

 	/* record pid to pidfile */
 	sprintf(str,"%d\n",getpid());
 	if (write(pidfile_fd,str,strlen(str)) < strlen(str)) {
 		syslog(LOG_ERR,"Could not write PID into PID file %s (%m) -- exiting",pidfile);
 		return 5; /* exitvalue */
 	}
 	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 */
 	signal(SIGINT,signal_handler); /* catch keyboard interrupt signal */

 	return 0;
 }

 void cleanup() {
 	cleanup_syslog();
 	unlink(pidfile);
 	close(pidfile_fd);
 	close(varlogfile_fd);
 }

 void usage(char * cmdname) {
 	fprintf (stderr,
 		"Usage: %s [options...] -- <command> [command-specific arguments...]\n"
 		"Daemonize any program.\n"
 		"\n"
 		"Options:\n"
 		"\n"
 		"	-l <logfile>:   log stdout/stderr to this *absolute* path (default "VARLOGFILE")\n"
 		"	-u <username>:   setuid() to this user name before starting the program (default "DEFAULTUSER")\n"
 		"	-p <pidfile>:   lock and write the PID to this *absolute* path (default "PIDFILE")\n"
 		"	-n <progname>:  name the daemon assumes (default "PROGNAME")\n"
 		"	-h: show this usage guide\n"
 		"\n"
 		"Exit status:\n"
 		" 0      if daemonized correctly\n"
 		" other  if an error took place\n"
 		"", cmdname);
 	exit(0);
 }

 int parse_args(int argc,char ** argv) {
 	int index;
 	int c;

 // 	pidfile = PIDFILE;
 // 	varlogfile = VARLOGFILE;
 // 	progname = PROGNAME;

 	opterr = 0;

 	while ((c = getopt (argc, argv, "l:p:n:u:")) != -1)
 		switch (c)
 		{
 			case 'l':
 				varlogfile = optarg;
 				break;
 			case 'p':
 				pidfile = optarg;
 				break;
 			case 'n':
 				progname = optarg;
 				break;
 			case 'u':
 				if (getuid() != 0) {
 					fprintf (stderr, "-u can only be used by root.\nSee help with -h\n", user);
 					exit(64);
 				}
 				user = optarg;
 				creds = getpwnam(user);
 				if (creds == NULL) {
 					fprintf (stderr, "User %s was not found in the user database.\nSee help with -h\n", user);
 					exit(63);
 				}
 				uid = creds->pw_uid; gid = creds->pw_gid;
 				break;
 // 			case 'h':
 // 				break;
 // 				usage(argv[0]); /* halts after this */
 			case '?':
 				if (optopt == '?' || optopt == 'h')
 					usage(argv[0]); /* halts after this */
 				if (optopt == 'l' || optopt == 'p' || optopt == 'n')
 					fprintf (stderr, "Option -%c requires an argument.\nSee help with -h\n", optopt);
 				else if (isprint (optopt))
 					fprintf (stderr, "Unknown option `-%c'.\nSee help with -h\n", optopt);
 				else
 					fprintf (stderr, "Unknown option character `\\x%x'.\nSee help with -h\n", optopt);
 				exit(64); /* exitvalue */
 			default:
 				abort ();
 		}

 	for (index = optind; index < argc; index++);

 	if (index == optind) {
 		fprintf (stderr, "You need to specify a command to run.\nSee help with -h\n", optopt);
 		exit(64); /* exitvalue */
 	}

 	return optind;
 }

 int main(int argc, char** argv)
 {
 	/* parse command line arguments, we will use the first non-option one as the starting point */
 	int i;
 	char ** newargv = calloc(argc+1, sizeof(char**));
 	int startat = parse_args(argc,argv);
 	int newargc = argc - startat;
 	for (i = startat; i < argc; i++) { newargv[i-startat] = argv[i]; }

 	/* try and daemonize */
 	int daemonret = daemonize(progname);
 	if (daemonret) exit(daemonret);
 	syslog(LOG_INFO,"successfully daemonized");

 	/* fork */
 	int pid, wpid, status, execret;
 	syslog(LOG_INFO,"starting %s in subprocess",newargv[0]);
 	pid = fork();
 	if (pid < 0) {
 		/* failed to fork, damnit! */
 		syslog(LOG_ERR,"could not fork to run %s as a child process (%m)",newargv[0]);
 		exit(4); /* exitvalue */
 	}
 	else if (pid == 0) {
 		/* child */
 		if (uid != 0) {
 			execret = setgid(gid);
 			if (execret == -1) {
 				syslog(LOG_ERR,"could not setgid() to gid %d",gid);
 				exit(8); /* exitvalue */
 			}
 			execret = setuid(uid);
 			if (execret == -1) {
 				syslog(LOG_ERR,"could not setuid() to uid %d",uid);
 				exit(8); /* exitvalue */
 			}
 		}
 		execret = execvp(newargv[0],newargv);
 		if (errno == 2) {
 			syslog(LOG_ERR,"could not run program: no such file or directory");
 			exit(127);
 		}
 		if (errno == 13) {
 			syslog(LOG_ERR,"could not run program: permission denied");
 			exit(126);
 		}
 		syslog(LOG_ERR,"could not run program: unknown reason");
 		exit(255);
 	}

 	/* parent continues here */
 	syslog(LOG_INFO,"successfully started subprocess -- PID %d",pid);
 	int finalexit = 0;
 	int waitret = 0;
 	while (1) {
 		if (killed) {
 			kill(pid,killsignal);
 			killed = 0;
 		}
 		waitret = waitpid(pid,&status,WNOHANG);
 		if (waitret == pid) break;
 		usleep(250000);
 	}


 	if WIFEXITED(status) {
 		switch (WEXITSTATUS(status)) {
 			case 0:
 				syslog(LOG_INFO,"%s exited normally",newargv[0]);
 				break;
 			case 126:
 				syslog(LOG_ERR,"%s: permission denied",newargv[0]);
 				finalexit = 126; /* exitvalue */
 				break;
 			case 127:
 				syslog(LOG_ERR,"%s: command not found",newargv[0]);
 				finalexit = 127; /* exitvalue */
 				break;
 			default:
 				syslog(LOG_INFO,"%s exited abnormally with status %d",newargv[0],WEXITSTATUS(status));
 				finalexit = 6; /* exitvalue */
 		}
 	}
 	if WIFSIGNALED(status) {
 		syslog(LOG_INFO,"%s was killed with signal %d",newargv[0],WTERMSIG(status));
 		finalexit = 7; /* exitvalue */
 	}

 	syslog(LOG_INFO,"shutting down");
 	cleanup();
 	exit(finalexit);
 }

 /* EOF */
	/*
	UNIX daemonizer. Daemonizes any non-interactive console program and watches over it.
	Whenever a signal is sent to this process, it halts the daemonized process as well.

	To compile: cc -o daemonize daemonize.c
	Usage: ./daemonize -?
	Users of this: catalina initscript
	*/

	#include <stdio.h>
	#include <fcntl.h>
	#include <signal.h>
	#include <unistd.h>
	#include <syslog.h>
	#include <string.h>
	#include <stdlib.h>
	#include <getopt.h>
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <sys/wait.h>
	#include <errno.h>
	#include <pwd.h>

	#define RUNNING_DIR "/"
	#define PIDFILE "/var/run/daemonize.pid"
	#define VARLOGFILE "/var/log/daemon.log"
	#define PROGNAME "daemonized"
	#define DEFAULTUSER "root"

	char * pidfile = PIDFILE;
	char * varlogfile = VARLOGFILE;
	char * progname = PROGNAME;
	char * user = PROGNAME;

	void initialize_syslog(const char*pn) {
	openlog(pn,LOG_PID,LOG_DAEMON);
	syslog(LOG_INFO, "syslog connection opened");
	}

	void cleanup_syslog() {
	syslog(LOG_INFO, "syslog connection closed");
	closelog();
	}

	int killed = 0;
	int killsignal = 0;
	int pidfile_fd;
	int varlogfile_fd;
	int uid = 0; int gid = 0;
	struct passwd *creds;

	void signal_handler(sig)
	int sig;
	{
	killsignal = sig;
	switch(sig) {
	case SIGCHLD:
	syslog(LOG_INFO,"sigchild signal caught");
	break;
	case SIGHUP:
	syslog(LOG_INFO,"hangup signal caught");
	killed = 1;
	break;
	case SIGTERM:
	syslog(LOG_INFO,"terminate signal caught");
	killed = 1;
	break;
	case SIGINT:
	syslog(LOG_INFO,"keyboard interrupt signal caught");
	killed = 1;
	break;
	}
	}

	int daemonize(const char*prog_name)
	{

	char str[10];
	int i;
	int bufsize=1024; char *buf = malloc(1024);

	umask( S_IWGRP \| S_IROTH \| S_IWOTH ); /* set newly created file permissions */

	/* test logfile */
	varlogfile_fd=open(varlogfile,O_RDWR\|O_CREAT\|O_APPEND,0666);
	if (varlogfile_fd == -1) {
	snprintf(buf,bufsize,"Could not open output file %s -- exiting",varlogfile); perror(buf);
	return 1; /* exitvalue */
	}
	if (uid != 0) {
	chown(varlogfile,uid,gid);
	}
	close(varlogfile_fd);
	pidfile_fd=open(pidfile,O_RDWR\|O_CREAT,0666);
	if (pidfile_fd<0) {
	snprintf(buf,bufsize,"The PID file %s cannot be opened -- exiting",pidfile); perror(buf);
	return 2; /* exitvalue */
	}
	if (lockf(pidfile_fd,F_TEST,0)==1) {
	snprintf(buf,bufsize,"A daemon is already running (cannot lock PID file %s) -- exiting",pidfile); perror(buf);
	return 3; /* exitvalue */
	}
	close(pidfile_fd);

	if(getppid()==1) return 0; /* already a daemon */
	i=fork();
	if (i < 0) return 4; /* exitvalue / / fork error */
	if (i > 0) exit(0); /* parent exits */

	/* child (daemon) continues */
	setsid(); /* obtain a new process group */

	chdir(RUNNING_DIR); /* change running directory */

	/* close FDs and reopen to logfile */
	for (i=getdtablesize();i>=0;--i) close(i); /* close all descriptors */
	varlogfile_fd=open(varlogfile,O_RDWR\|O_APPEND,0666); dup(varlogfile_fd); dup(varlogfile_fd); /* handle standart I/O */
	initialize_syslog(prog_name); /* set up syslog */

	/* PID file */
	pidfile_fd=open(pidfile,O_RDWR\|O_CREAT,0666);
	if (pidfile_fd<0) {
	syslog(LOG_ERR,"The PID file %s cannot be opened (%m) -- exiting",pidfile);
	return 2; /* exitvalue */
	}
	if (lockf(pidfile_fd,F_TLOCK,0)<0) {
	syslog(LOG_ERR,"A daemon is already running -- cannot lock PID file %s (%m) -- exiting",pidfile);
	return 3; /* exitvalue */
	}

	/* first instance continues */

	/* record pid to pidfile */
	sprintf(str,"%d\n",getpid());
	if (write(pidfile_fd,str,strlen(str)) < strlen(str)) {
	syslog(LOG_ERR,"Could not write PID into PID file %s (%m) -- exiting",pidfile);
	return 5; /* exitvalue */
	}
	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 */
	signal(SIGINT,signal_handler); /* catch keyboard interrupt signal */

	return 0;
	}

	void cleanup() {
	cleanup_syslog();
	unlink(pidfile);
	close(pidfile_fd);
	close(varlogfile_fd);
	}

	void usage(char * cmdname) {
	fprintf (stderr,
	"Usage: %s [options...] -- <command> [command-specific arguments...]\n"
	"Daemonize any program.\n"
	"\n"
	"Options:\n"
	"\n"
	" -l <logfile>: log stdout/stderr to this absolute path (default "VARLOGFILE")\n"
	" -u <username>: setuid() to this user name before starting the program (default "DEFAULTUSER")\n"
	" -p <pidfile>: lock and write the PID to this absolute path (default "PIDFILE")\n"
	" -n <progname>: name the daemon assumes (default "PROGNAME")\n"
	" -h: show this usage guide\n"
	"\n"
	"Exit status:\n"
	" 0 if daemonized correctly\n"
	" other if an error took place\n"
	"", cmdname);
	exit(0);
	}

	int parse_args(int argc,char ** argv) {
	int index;
	int c;

	// pidfile = PIDFILE;
	// varlogfile = VARLOGFILE;
	// progname = PROGNAME;

	opterr = 0;

	while ((c = getopt (argc, argv, "l:p:n:u:")) != -1)
	switch (c)
	{
	case 'l':
	varlogfile = optarg;
	break;
	case 'p':
	pidfile = optarg;
	break;
	case 'n':
	progname = optarg;
	break;
	case 'u':
	if (getuid() != 0) {
	fprintf (stderr, "-u can only be used by root.\nSee help with -h\n", user);
	exit(64);
	}
	user = optarg;
	creds = getpwnam(user);
	if (creds == NULL) {
	fprintf (stderr, "User %s was not found in the user database.\nSee help with -h\n", user);
	exit(63);
	}
	uid = creds->pw_uid; gid = creds->pw_gid;
	break;
	// case 'h':
	// break;
	// usage(argv[0]); /* halts after this */
	case '?':
	if (optopt == '?' \|\| optopt == 'h')
	usage(argv[0]); /* halts after this */
	if (optopt == 'l' \|\| optopt == 'p' \|\| optopt == 'n')
	fprintf (stderr, "Option -%c requires an argument.\nSee help with -h\n", optopt);
	else if (isprint (optopt))
	fprintf (stderr, "Unknown option `-%c'.\nSee help with -h\n", optopt);
	else
	fprintf (stderr, "Unknown option character `\\x%x'.\nSee help with -h\n", optopt);
	exit(64); /* exitvalue */
	default:
	abort ();
	}

	for (index = optind; index < argc; index++);

	if (index == optind) {
	fprintf (stderr, "You need to specify a command to run.\nSee help with -h\n", optopt);
	exit(64); /* exitvalue */
	}

	return optind;
	}

	int main(int argc, char** argv)
	{
	/* parse command line arguments, we will use the first non-option one as the starting point */
	int i;
	char newargv = calloc(argc+1, sizeof(char));
	int startat = parse_args(argc,argv);
	int newargc = argc - startat;
	for (i = startat; i < argc; i++) { newargv[i-startat] = argv[i]; }

	/* try and daemonize */
	int daemonret = daemonize(progname);
	if (daemonret) exit(daemonret);
	syslog(LOG_INFO,"successfully daemonized");

	/* fork */
	int pid, wpid, status, execret;
	syslog(LOG_INFO,"starting %s in subprocess",newargv[0]);
	pid = fork();
	if (pid < 0) {
	/* failed to fork, damnit! */
	syslog(LOG_ERR,"could not fork to run %s as a child process (%m)",newargv[0]);
	exit(4); /* exitvalue */
	}
	else if (pid == 0) {
	/* child */
	if (uid != 0) {
	execret = setgid(gid);
	if (execret == -1) {
	syslog(LOG_ERR,"could not setgid() to gid %d",gid);
	exit(8); /* exitvalue */
	}
	execret = setuid(uid);
	if (execret == -1) {
	syslog(LOG_ERR,"could not setuid() to uid %d",uid);
	exit(8); /* exitvalue */
	}
	}
	execret = execvp(newargv[0],newargv);
	if (errno == 2) {
	syslog(LOG_ERR,"could not run program: no such file or directory");
	exit(127);
	}
	if (errno == 13) {
	syslog(LOG_ERR,"could not run program: permission denied");
	exit(126);
	}
	syslog(LOG_ERR,"could not run program: unknown reason");
	exit(255);
	}

	/* parent continues here */
	syslog(LOG_INFO,"successfully started subprocess -- PID %d",pid);
	int finalexit = 0;
	int waitret = 0;
	while (1) {
	if (killed) {
	kill(pid,killsignal);
	killed = 0;
	}
	waitret = waitpid(pid,&status,WNOHANG);
	if (waitret == pid) break;
	usleep(250000);
	}


	if WIFEXITED(status) {
	switch (WEXITSTATUS(status)) {
	case 0:
	syslog(LOG_INFO,"%s exited normally",newargv[0]);
	break;
	case 126:
	syslog(LOG_ERR,"%s: permission denied",newargv[0]);
	finalexit = 126; /* exitvalue */
	break;
	case 127:
	syslog(LOG_ERR,"%s: command not found",newargv[0]);
	finalexit = 127; /* exitvalue */
	break;
	default:
	syslog(LOG_INFO,"%s exited abnormally with status %d",newargv[0],WEXITSTATUS(status));
	finalexit = 6; /* exitvalue */
	}
	}
	if WIFSIGNALED(status) {
	syslog(LOG_INFO,"%s was killed with signal %d",newargv[0],WTERMSIG(status));
	finalexit = 7; /* exitvalue */
	}

	syslog(LOG_INFO,"shutting down");
	cleanup();
	exit(finalexit);
	}

	/* EOF */