[PATCH] slcan2d: add new slcan daemon

[yegorslists@googlemail.com]

From: Yegor Yefremov <yegorslists@googlemail.com>

Cleaned up version of Oliver Hartkopp's effort with addition of
UART speed configuration.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
---
 GNUmakefile.am |    1 +
 slcan2d.c      |  519 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 520 insertions(+), 0 deletions(-)
 create mode 100644 slcan2d.c

diff --git a/GNUmakefile.am b/GNUmakefile.am
index fc8f6e7..e4d7de3 100644
--- a/GNUmakefile.am
+++ b/GNUmakefile.am
@@ -59,6 +59,7 @@ bin_PROGRAMS = \
 	log2long \
 	slcan_attach \
 	slcand \
+	slcan2d \
 	slcanpty
 
 EXTRA_DIST = \
diff --git a/slcan2d.c b/slcan2d.c
new file mode 100644
index 0000000..62672e3
--- /dev/null
+++ b/slcan2d.c
@@ -0,0 +1,519 @@
+/*
+ * slcan2d.c - userspace daemon for serial line CAN interface driver SLCAN
+ *
+ * Copyright (c) 2009 Robert Haddon <robert.haddon@verari.com>
+ * Copyright (c) 2009 Verari Systems Inc.
+ *
+ * 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
+ *
+ * This code is derived from an example daemon code from
+ *
+ * http://en.wikipedia.org/wiki/Daemon_(computer_software)#Sample_Program_in_C_on_Linux
+ * (accessed 2009-05-05)
+ *
+ * So it is additionally licensed under the GNU Free Documentation License:
+ *
+ * Permission is granted to copy, distribute and/or modify this document
+ * under the terms of the GNU Free Documentation License, Version 1.2
+ * or any later version published by the Free Software Foundation;
+ * with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
+ * A copy of the license is included in the section entitled "GNU
+ * Free Documentation License".
+ *
+ * Send feedback to <linux-can@vger.kernel.org>
+ *
+ */
+
+#include <stdio.h>
+#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/ioctl.h>
+#include <net/if.h>
+#include <termios.h>
+
+/* default slcan line discipline since Kernel 2.6.25 */
+#define LDISC_N_SLCAN 17
+
+/* Change this to whatever your daemon is called */
+#define DAEMON_NAME "slcan2d"
+
+/* Change this to the user under which to run */
+#define RUN_AS_USER "root"
+
+/* The length of ttypath buffer */
+#define TTYPATH_LENGTH	64
+
+/* The length of pidfile name buffer */
+#define PIDFILE_LENGTH	64
+
+#define EXIT_SUCCESS 0
+#define EXIT_FAILURE 1
+
+
+
+void print_usage(char *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)\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, "slcan2d -o -c -f -s6 ttyslcan0\n");
+	fprintf(stderr, "slcan2d -o -c -f -s6 ttyslcan0 can0\n");
+	fprintf(stderr, "\n");
+	exit(EXIT_FAILURE);
+}
+
+
+static int slcan2d_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 SIGUSR1:
+		/* exit parent */
+		exit(EXIT_SUCCESS);
+		break;
+	case SIGALRM:
+	case SIGCHLD:
+		syslog (LOG_NOTICE, "received signal %i on %s", signum, ttypath);
+		exit_code = EXIT_FAILURE;
+		slcan2d_running = 0;
+		break;
+	case SIGINT:
+	case SIGTERM:
+		syslog (LOG_NOTICE, "received signal %i on %s", signum, ttypath);
+		exit_code = EXIT_SUCCESS;
+		slcan2d_running = 0;
+		break;
+	}
+}
+
+static int look_up_uart_speed(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 B57600;
+	}
+}
+
+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";
+
+	snprintf(pidfile, PIDFILE_LENGTH, "%s%s-%s%s", pidprefix, DAEMON_NAME, tty, pidsuffix);
+
+	/* already a daemon */
+	if (getppid () == 1)
+		return 0;
+
+	/* Create the lock file as the current user */
+	if (lockfile && lockfile[0])
+	{
+		lfp = open (lockfile, O_RDWR | O_CREAT, 0640);
+		if (lfp < 0)
+		{
+			syslog (LOG_ERR, "unable to create lock file %s, code=%d (%s)",
+				lockfile, errno, strerror (errno));
+			exit (EXIT_FAILURE);
+		}
+	}
+
+	/* Drop user if there is one, and we were run as root */
+	if (getuid () == 0 || geteuid () == 0)
+	{
+		struct passwd *pw = getpwnam (RUN_AS_USER);
+		if (pw)
+		{
+			//syslog (LOG_NOTICE, "setting user to " RUN_AS_USER);
+			setuid (pw->pw_uid);
+		}
+	}
+
+	/* 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);
+
+	/* Fork off the parent process */
+	pid = fork ();
+	if (pid < 0)
+	{
+		syslog (LOG_ERR, "unable to fork daemon, code=%d (%s)",
+			errno, strerror (errno));
+		exit (EXIT_FAILURE);
+	}
+	/* If we got a good PID, then we can exit the parent process. */
+	if (pid > 0)
+	{
+
+		/* Wait for confirmation from the child via SIGTERM or SIGCHLD, or
+		   for two seconds to elapse (SIGALRM).  pause() should not return. */
+		alarm (5);
+		pause ();
+		exit (EXIT_FAILURE);
+	}
+
+	/* At this point we are executing as the child process */
+	parent = getppid ();
+
+	/* Cancel certain signals */
+	signal (SIGCHLD, SIG_DFL);	/* A child process dies */
+	signal (SIGTSTP, SIG_IGN);	/* Various TTY signals */
+	signal (SIGTTOU, SIG_IGN);
+	signal (SIGTTIN, SIG_IGN);
+	signal (SIGHUP, SIG_IGN);	/* Ignore hangup signal */
+	signal (SIGINT, child_handler);
+	signal (SIGTERM, child_handler);
+
+	/* Change the file mode mask */
+	umask (0);
+
+	/* Create a new SID for the child process */
+	sid = setsid ();
+	if (sid < 0)
+	{
+		syslog (LOG_ERR, "unable to create a new session, code %d (%s)",
+			errno, strerror (errno));
+		exit (EXIT_FAILURE);
+	}
+
+	pFile = fopen (pidfile,"w");
+	if (NULL == pFile)
+	{
+		syslog (LOG_ERR, "unable to create pid file %s, code=%d (%s)",
+			pidfile, errno, strerror (errno));
+		exit (EXIT_FAILURE);
+	}
+	fprintf (pFile, "%d\n", sid);
+	fclose (pFile);
+
+	/* Change the current working directory.  This prevents the current
+	   directory from being locked; hence not being able to remove it. */
+	if ((chdir ("/")) < 0)
+	{
+		syslog (LOG_ERR, "unable to change directory to %s, code %d (%s)",
+			"/", errno, strerror (errno));
+		exit (EXIT_FAILURE);
+	}
+
+	/* Redirect standard files to /dev/null */
+	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);
+	return parent;
+}
+
+int main (int argc, char *argv[])
+{
+	char *tty = NULL;
+	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 detach = 1;
+	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]);
+			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]);
+			//exit(EXIT_SUCCESS);
+			break;
+		}
+	}
+
+	/* Initialize the logging interface */
+	openlog (DAEMON_NAME, LOG_PID, LOG_LOCAL5);
+
+	/* 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;
+	pch = strstr (tty, devprefix);
+	if (pch == tty) {
+		print_usage(argv[0]);
+	}
+
+	snprintf (ttypath, TTYPATH_LENGTH, "%s%s", devprefix, tty);
+	syslog (LOG_INFO, "starting on TTY device %s", ttypath);
+
+	/* Daemonize */
+	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);
+	}
+
+	/* */
+	slcan2d_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_RDWR | O_NONBLOCK | O_NOCTTY )) < 0) {
+	    syslog (LOG_NOTICE, "failed to open TTY device %s\n", ttypath);
+		perror(ttypath);
+		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 */
+	if (ioctl (fd, TIOCSETD, &ldisc) < 0) {
+		perror("ioctl TIOCSETD");
+		exit(1);
+	}
+	
+	/* retrieve the name of the created CAN netdevice */
+	if (ioctl (fd, SIOCGIFNAME, buf) < 0) {
+		perror("ioctl SIOCGIFNAME");
+		exit(1);
+	}
+
+	syslog (LOG_NOTICE, "attached TTY %s to netdevice %s\n", ttypath, buf);
+	
+	/* try to rename the created netdevice */
+	if (name) {
+		struct ifreq ifr;
+		int s = socket(PF_INET, SOCK_DGRAM, 0);
+		if (s < 0)
+			perror("socket for interface rename");
+		else {
+			strncpy (ifr.ifr_name, buf, IFNAMSIZ);
+			strncpy (ifr.ifr_newname, name, IFNAMSIZ);
+
+			if (ioctl(s, SIOCSIFNAME, &ifr) < 0) {
+				syslog (LOG_NOTICE, "netdevice %s rename to %s failed\n", buf, name);
+				perror("ioctl SIOCSIFNAME rename");
+                exit(1);
+			} else
+				syslog (LOG_NOTICE, "netdevice %s renamed to %s\n", buf, name);
+
+			close(s);
+		}	
+	}
+	if(parent_pid > 0) {
+		kill(parent_pid, SIGUSR1);
+	}
+
+	/* The Big Loop */
+	while (slcan2d_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(1);
+	}
+
+	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 exit_code;
+}
-- 
1.7.7