slcand: add slcan_attach and UART settings

slcand takes settings known from slcan_attach to configure CAN
interface, like open/close channel, set bitrate etc (Oliver Hartkopp).

In addition -S option sets UART's baudrate (Yegor Yefremov).

This way slcand combines three autilities in one: old slcand,
slcan_attach and stty.

Example: slcand -o -s8 -S 3000000 ttyUSB0

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Reviewed-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>

slcand.c

@@ -40,16 +40,16 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 #include <fcntl.h>
 #include <syslog.h>
 #include <errno.h>
 #include <pwd.h>
 #include <signal.h>
-#include <sys/socket.h>
 #include <sys/ioctl.h>
-#include <sys/types.h>
-#include <sys/stat.h>
 #include <net/if.h>
+#include <termios.h>
 
 /* default slcan line discipline since Kernel 2.6.25 */
 #define LDISC_N_SLCAN 17
@@ -71,44 +71,119 @@
 
 void print_usage(char *prg)
 {
-	fprintf(stderr, "\nUsage: %s tty [name]\n\n", prg);
+	fprintf(stderr, "\nUsage: %s [options] <tty> [canif-name]\n\n", prg);
-	fprintf(stderr, "Example:\n");
+	fprintf(stderr, "Options: -o         (send open command 'O\\r')\n");
-	fprintf(stderr, "%s ttyUSB1\n", prg);
+	fprintf(stderr, "         -c         (send close command 'C\\r')\n");
-	fprintf(stderr, "%s ttyS0 can0\n", prg);
+	fprintf(stderr, "         -f         (read status flags with 'F\\r' to reset error states)\n");
+	fprintf(stderr, "         -s <speed> (set CAN speed 0..8)\n");
+	fprintf(stderr, "         -S <speed> (set UART speed in baud)\n");
+	fprintf(stderr, "         -b <btr>   (set bit time register value)\n");
+	fprintf(stderr, "         -F         (stay in foreground; no daemonize)\n");
+	fprintf(stderr, "         -h         (show this help page)\n");
+	fprintf(stderr, "\nExamples:\n");
+	fprintf(stderr, "slcand -o -c -f -s6 ttyslcan0\n");
+	fprintf(stderr, "slcand -o -c -f -s6 ttyslcan0 can0\n");
 	fprintf(stderr, "\n");
 	exit(EXIT_FAILURE);
 }
 
+static int slcand_running = 0;
+static int exit_code = 0;
+static char ttypath[TTYPATH_LENGTH];
+static char pidfile[PIDFILE_LENGTH];
+
 static void child_handler (int signum)
 {
-	switch (signum)
+	switch (signum) {
-	{
-	case SIGALRM:
-		exit (EXIT_FAILURE);
-		break;
 	case SIGUSR1:
-		exit (EXIT_SUCCESS);
+		/* exit parent */
+		exit(EXIT_SUCCESS);
 		break;
+	case SIGALRM:
 	case SIGCHLD:
-		exit (EXIT_FAILURE);
+		syslog (LOG_NOTICE, "received signal %i on %s", signum, ttypath);
+		exit_code = EXIT_FAILURE;
+		slcand_running = 0;
+		break;
+	case SIGINT:
+	case SIGTERM:
+		syslog (LOG_NOTICE, "received signal %i on %s", signum, ttypath);
+		exit_code = EXIT_SUCCESS;
+		slcand_running = 0;
 		break;
 	}
 }
 
-static void daemonize (const char *lockfile, char *tty)
+static int look_up_uart_speed(long int s)
+{
+	switch (s) {
+	case 9600:
+		return B9600;
+	case 19200:
+		return B19200;
+	case 38400:
+		return B38400;
+	case 57600:
+		return B57600;
+	case 115200:
+		return B115200;
+	case 230400:
+		return B230400;
+	case 460800:
+		return B460800;
+	case 500000:
+		return B500000;
+	case 576000:
+		return B576000;
+	case 921600:
+		return B921600;
+	case 1000000:
+		return B1000000;
+	case 1152000:
+		return B1152000;
+	case 1500000:
+		return B1500000;
+	case 2000000:
+		return B2000000;
+#ifdef B2500000
+	case 2500000:
+		return B2500000;
+#endif
+#ifdef B3000000
+	case 3000000:
+		return B3000000;
+#endif
+#ifdef B3500000
+	case 3500000:
+		return B3500000;
+#endif
+#ifdef B3710000
+	case 3710000
+		return B3710000;
+#endif
+#ifdef B4000000
+	case 4000000:
+		return B4000000;
+#endif
+	default:
+		return -1;
+	}
+}
+
+static pid_t daemonize (const char *lockfile, char *tty, char *name)
 {
 	pid_t pid, sid, parent;
 	int lfp = -1;
 	FILE * pFile;
+	FILE * dummyFile;
 	char const *pidprefix = "/var/run/";
 	char const *pidsuffix = ".pid";
-	char pidfile[PIDFILE_LENGTH];
 
 	snprintf(pidfile, PIDFILE_LENGTH, "%s%s-%s%s", pidprefix, DAEMON_NAME, tty, pidsuffix);
 
 	/* already a daemon */
 	if (getppid () == 1)
-		return;
+		return 0;
 
 	/* Create the lock file as the current user */
 	if (lockfile && lockfile[0])
@@ -134,6 +209,8 @@ static void daemonize (const char *lockfile, char *tty)
 	}
 
 	/* Trap signals that we expect to receive */
+	signal (SIGINT, child_handler);
+	signal (SIGTERM, child_handler);
 	signal (SIGCHLD, child_handler);
 	signal (SIGUSR1, child_handler);
 	signal (SIGALRM, child_handler);
@@ -151,10 +228,9 @@ static void daemonize (const char *lockfile, char *tty)
 	{
 
 		/* Wait for confirmation from the child via SIGTERM or SIGCHLD, or
-		   for two seconds to elapse (SIGALRM).  pause() should not return. */
+		   for five seconds to elapse (SIGALRM).  pause() should not return. */
-		alarm (2);
+		alarm (5);
 		pause ();
-
 		exit (EXIT_FAILURE);
 	}
 
@@ -167,7 +243,8 @@ static void daemonize (const char *lockfile, char *tty)
 	signal (SIGTTOU, SIG_IGN);
 	signal (SIGTTIN, SIG_IGN);
 	signal (SIGHUP, SIG_IGN);	/* Ignore hangup signal */
-	signal (SIGTERM, SIG_DFL);	/* Die on SIGTERM */
+	signal (SIGINT, child_handler);
+	signal (SIGTERM, child_handler);
 
 	/* Change the file mode mask */
 	umask (0);
@@ -182,7 +259,7 @@ static void daemonize (const char *lockfile, char *tty)
 	}
 
 	pFile = fopen (pidfile,"w");
-	if (pFile == NULL)
+	if (NULL == pFile)
 	{
 		syslog (LOG_ERR, "unable to create pid file %s, code=%d (%s)",
 			pidfile, errno, strerror (errno));
@@ -201,36 +278,90 @@ static void daemonize (const char *lockfile, char *tty)
 	}
 
 	/* Redirect standard files to /dev/null */
-	freopen ("/dev/null", "r", stdin);
+	dummyFile = freopen ("/dev/null", "r", stdin);
-	freopen ("/dev/null", "w", stdout);
+	dummyFile = freopen ("/dev/null", "w", stdout);
-	freopen ("/dev/null", "w", stderr);
+	dummyFile = freopen ("/dev/null", "w", stderr);
 
 	/* Tell the parent process that we are A-okay */
-	kill (parent, SIGUSR1);
+	//kill (parent, SIGUSR1);
+	return parent;
 }
 
 int main (int argc, char *argv[])
 {
 	char *tty = NULL;
-	char ttypath[TTYPATH_LENGTH];
 	char const *devprefix = "/dev/";
 	char *name = NULL;
 	char buf[IFNAMSIZ+1];
+	struct termios tios;
+	speed_t old_ispeed;
+	speed_t old_ospeed;
+
+	int opt;
+	int send_open = 0;
+	int send_close = 0;
+	int send_read_status_flags = 0;
+	char *speed = NULL;
+	char *uart_speed_str = NULL;
+	long int uart_speed = 0;
+	char *btr = NULL;
+	int run_as_daemon = 1;
+	pid_t parent_pid = 0;
+
+	ttypath[0] = '\0';
+
+	while ((opt = getopt(argc, argv, "ocfs:S:b:?hF")) != -1) {
+		switch (opt) {
+		case 'o':
+			send_open = 1;
+			break;
+		case 'c':
+			send_close = 1;
+			break;
+		case 'f':
+			send_read_status_flags = 1;
+			break;
+		case 's':
+			speed = optarg;
+			if (strlen(speed) > 1)
+				print_usage(argv[0]);
+			break;
+		case 'S':
+			uart_speed_str = optarg;
+			errno = 0;
+			uart_speed = strtol(uart_speed_str, NULL, 10);
+			if (errno)
+				print_usage(argv[0]);
+			if (look_up_uart_speed(uart_speed) == -1) {
+				fprintf(stderr, "Unsupported UART speed (%lu)\n", uart_speed);
+				exit(EXIT_FAILURE);
+			}
+			break;
+		case 'b':
+			btr = optarg;
+			if (strlen(btr) > 6)
+				print_usage(argv[0]);
+			break;
+		case 'F':
+			run_as_daemon = 0;
+			break;
+		case 'h':
+		case '?':
+		default:
+			print_usage(argv[0]);
+			break;
+		}
+	}
 
 	/* Initialize the logging interface */
 	openlog (DAEMON_NAME, LOG_PID, LOG_LOCAL5);
 
-	/* See how we're called */
+	/* Parse serial device name and optional can interface name */
-	if (argc == 2) {
+	tty = argv[optind];
-		tty = argv[1];
+	if(NULL == tty) {
-	} else if (argc == 3) {
-		tty = argv[1];
-		name = argv[2];
-		if (strlen(name) > IFNAMSIZ-1)
-			print_usage(argv[0]);
-	} else {
 		print_usage(argv[0]);
 	}
+	name = argv[optind + 1];
 
 	/* Prepare the tty device name string */
 	char * pch;
@@ -243,16 +374,68 @@ int main (int argc, char *argv[])
 	syslog (LOG_INFO, "starting on TTY device %s", ttypath);
 
 	/* Daemonize */
-	daemonize ("/var/lock/" DAEMON_NAME, tty);
+	if(run_as_daemon) {
+		parent_pid = daemonize ("/var/lock/" DAEMON_NAME, tty, name);
+	}
+	else {
+		/* Trap signals that we expect to receive */
+		signal (SIGINT, child_handler);
+		signal (SIGTERM, child_handler);
+	}
+
+	/* */
+	slcand_running = 1;
 
 	/* Now we are a daemon -- do the work for which we were paid */
 	int fd;
 	int ldisc = LDISC_N_SLCAN;
 
-	if ((fd = open (ttypath, O_WRONLY | O_NOCTTY )) < 0) {
+	if ((fd = open (ttypath, O_RDWR | O_NONBLOCK | O_NOCTTY )) < 0) {
 	    syslog (LOG_NOTICE, "failed to open TTY device %s\n", ttypath);
 		perror(ttypath);
-		exit(1);
+		exit(EXIT_FAILURE);
+	}
+
+	/* Configure baud rate */
+	memset(&tios, 0, sizeof(struct termios));
+	if(tcgetattr(fd, &tios) < 0) {
+		syslog (LOG_NOTICE, "failed to get attributes for TTY device %s: %s\n", ttypath, strerror(errno));
+		exit (EXIT_FAILURE);
+	}
+
+	/* Get old values for later restore */
+	old_ispeed = cfgetispeed(&tios);
+	old_ospeed = cfgetospeed(&tios);
+
+	/* Baud Rate */
+	cfsetispeed(&tios, look_up_uart_speed(uart_speed));
+	cfsetospeed(&tios, look_up_uart_speed(uart_speed));
+
+	/* apply changes */
+	if(tcsetattr(fd, TCSADRAIN, &tios) < 0) {
+		syslog(LOG_NOTICE, "Cannot set attributes for device \"%s\": %s!\n", ttypath, strerror(errno));
+	}
+
+	if (speed) {
+		sprintf(buf, "C\rS%s\r", speed);
+		if(write(fd, buf, strlen(buf)) < 0) {
+			//syslog (LO, "failed to get attributes for TTY device %s: %s\n", ttypath, strerror(errno));
+		}
+	}
+
+	if (btr) {
+		sprintf(buf, "C\rs%s\r", btr);
+		write(fd, buf, strlen(buf));
+	}
+
+	if (send_read_status_flags) {
+		sprintf(buf, "F\r");
+		write(fd, buf, strlen(buf));
+	}
+
+	if (send_open) {
+		sprintf(buf, "O\r");
+		write(fd, buf, strlen(buf));
 	}
 
 	/* set slcan like discipline on given tty */
@@ -289,14 +472,44 @@ int main (int argc, char *argv[])
 			close(s);
 		}	
 	}
+	if(parent_pid > 0) {
+		kill(parent_pid, SIGUSR1);
+	}
 
 	/* The Big Loop */
-	while (1) {
+	while (slcand_running) {
-		sleep(60); /* wait 60 seconds */
+		sleep(1); /* wait 1 second */
+	}
+
+	/* Reset line discipline */
+	syslog (LOG_INFO, "stopping on TTY device %s", ttypath);
+	ldisc = N_TTY;
+	if (ioctl (fd, TIOCSETD, &ldisc) < 0) {
+		perror("ioctl TIOCSETD");
+		exit(EXIT_FAILURE);
+	}
+
+	if (send_close) {
+		sprintf(buf, "C\r");
+		write(fd, buf, strlen(buf));
+	}
+
+	/* Reset old rates */
+	cfsetispeed(&tios, old_ispeed);
+	cfsetospeed(&tios, old_ospeed);
+
+	/* apply changes */
+	if(tcsetattr(fd, TCSADRAIN, &tios) < 0) {
+		syslog(LOG_NOTICE, "Cannot set attributes for device \"%s\": %s!\n", ttypath, strerror(errno));
+	}
+
+	/* Remove pidfile */
+	if(run_as_daemon) {
+		unlink(pidfile);
 	}
 
 	/* Finish up */
 	syslog (LOG_NOTICE, "terminated on %s", ttypath);
 	closelog ();
-	return 0;
+	return exit_code;
 }