Re: [PATCH v3] slcand: add slcan_attach and UART settings

[Stefan Wahren <stefan.wahren@i2se.com>]

Hello Yegor,

Am 13.09.2013 12:11, schrieb yegorslists@googlemail.com:
> From: Yegor Yefremov <yegorslists@googlemail.com>
>
> 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>
> CC: stefan.wahren@i2se.com
> CC: socketcan@hartkopp.net
> CC: mkl@pengutronix.de
> ---
> Changes since v2:
>    More style fixes as suggested by Stefan Wahren
> Changes since v1:
>    Implement suggestions from Stefan Wahren
>    - fix style issues
>    - changed look_up_uart_speed parameter from int to long int
>    - look_up_uart_speed return value will be checked for unsupported baudrates
>   slcand.c |  297 +++++++++++++++++++++++++++++++++++++++++++++++++++++---------
>   1 files changed, 255 insertions(+), 42 deletions(-)
>
> diff --git a/slcand.c b/slcand.c
> index 807ffaa..7708d9f 100644
> --- a/slcand.c
> +++ b/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, "Example:\n");
> -	fprintf(stderr, "%s ttyUSB1\n", prg);
> -	fprintf(stderr, "%s ttyS0 can0\n", prg);
> +	fprintf(stderr, "\nUsage: %s [options] <tty> [canif-name]\n\n", prg);
> +	fprintf(stderr, "Options: -o         (send open command 'O\\r')\n");
> +	fprintf(stderr, "         -c         (send close command 'C\\r')\n");
> +	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)
> -	{
> -	case SIGALRM:
> -		exit (EXIT_FAILURE);
> -		break;
> +	switch (signum) {
>   	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 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 void daemonize (const char *lockfile, char *tty)
> +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. */
> -		alarm (2);
> +		   for five seconds to elapse (SIGALRM).  pause() should not return. */
> +		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);
> -	freopen ("/dev/null", "w", stdout);
> -	freopen ("/dev/null", "w", stderr);
> +	dummyFile = freopen ("/dev/null", "r", stdin);
> +	dummyFile = freopen ("/dev/null", "w", stdout);
> +	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 */
> -	if (argc == 2) {
> -		tty = argv[1];
> -	} else if (argc == 3) {
> -		tty = argv[1];
> -		name = argv[2];
> -		if (strlen(name) > IFNAMSIZ-1)
> -			print_usage(argv[0]);
> -	} else {
> +	/* Parse serial device name and optional can interface name */
> +	tty = argv[optind];
> +	if(NULL == tty) {
>   		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) {
> -		sleep(60); /* wait 60 seconds */
> +	while (slcand_running) {
> +		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;
>   }

okay, looks good to me.

Best regards

Stefan