--- /dev/null
+/*
+ * $Id$
+ */
+
+/*
+ * slcand.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 <socketcan-users@lists.berlios.de>
+ *
+ */
+
+#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>
+
+/* 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 "slcand"
+
+/* Change this to the user under which to run */
+#define RUN_AS_USER "root"
+
+#define EXIT_SUCCESS 0
+#define EXIT_FAILURE 1
+
+void print_usage(char *prg)
+{
+ fprintf(stderr, "\nUsage: %s tty\n\n", prg);
+ fprintf(stderr, "Example:\n");
+ fprintf(stderr, "%s ttyUSB1\n", prg);
+ fprintf(stderr, "%s ttyS0\n", prg);
+ fprintf(stderr, "\n");
+ exit(EXIT_FAILURE);
+}
+
+static void child_handler (int signum)
+{
+ switch (signum)
+ {
+ case SIGALRM:
+ exit (EXIT_FAILURE);
+ break;
+ case SIGUSR1:
+ exit (EXIT_SUCCESS);
+ break;
+ case SIGCHLD:
+ exit (EXIT_FAILURE);
+ break;
+ }
+}
+
+static void daemonize (const char *lockfile, char *tty)
+{
+ pid_t pid, sid, parent;
+ int lfp = -1;
+ FILE * pFile;
+ char const *pidprefix = "/var/run/";
+ char const *pidsuffix = ".pid";
+ char *pidfile;
+ pidfile = malloc((strlen(pidprefix) +strlen(DAEMON_NAME) + strlen(tty) + strlen(pidsuffix) + 1) * sizeof(char));
+ sprintf(pidfile, "%s%s-%s%s", pidprefix, DAEMON_NAME, tty, pidsuffix);
+
+ /* already a daemon */
+ if (getppid () == 1)
+ return;
+
+ /* 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 (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 (2);
+ 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 (SIGTERM, SIG_DFL); /* Die on SIGTERM */
+
+ /* 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 (pFile < 0)
+ {
+ 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 */
+ freopen ("/dev/null", "r", stdin);
+ freopen ("/dev/null", "w", stdout);
+ freopen ("/dev/null", "w", stderr);
+
+ /* Tell the parent process that we are A-okay */
+ kill (parent, SIGUSR1);
+}
+
+int main (int argc, char *argv[])
+{
+ char *tty;
+ char *ttypath;
+ char const *devprefix = "/dev/";
+
+ /* Initialize the logging interface */
+ openlog (DAEMON_NAME, LOG_PID, LOG_LOCAL5);
+
+ /* See how we're called */
+ if (argc != 2)
+ print_usage(argv[0]);
+ tty = argv[1];
+
+ /* Prepare the tty device name string */
+ char * pch;
+ pch = strstr (tty, devprefix);
+ if (pch == tty) {
+ print_usage(argv[0]);
+ }
+ ttypath = malloc((strlen(devprefix) + strlen(tty)) * sizeof(char));
+ sprintf (ttypath, "%s%s", devprefix, tty);
+ syslog (LOG_INFO, "starting on TTY device %s", ttypath);
+
+ /* Daemonize */
+ daemonize ("/var/lock/" DAEMON_NAME, tty);
+
+ /* 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) {
+ perror(ttypath);
+ exit(1);
+ }
+
+ if (ioctl (fd, TIOCSETD, &ldisc) < 0) {
+ perror("ioctl");
+ exit(1);
+ }
+
+ /* The Big Loop */
+ while (1) {
+ sleep(60); /* wait 60 seconds */
+ }
+
+ /* Finish up */
+ syslog (LOG_NOTICE, "terminated on %s", ttypath);
+ closelog ();
+ return 0;
+}
projects / sojka / can-utils.git / commitdiff