slcand: reimplement daemonize routine

Replace daemonize() routine with daemone() system call, because of
conflicting licenses. daemonize() routine was derived from under
GNU Free Documentation License licensed code. This license is
incompatible with GPL-2+.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/slcand.c b/slcand.c
index 24af9717482d2412f6c3885a772867375e011643..69d30f7b2064472b841bb31d617b5048aa79a2f2 100644 (file)
--- a/slcand.c
+++ b/slcand.c
@@ -18,20 +18,6 @@
  * 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>
  *
  */
@@ -63,9 +49,6 @@
 /* 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
 
@@ -96,7 +79,6 @@ void print_usage(char *prg)
 static int slcand_running;
 static int exit_code;
 static char ttypath[TTYPATH_LENGTH];
-static char pidfile[PIDFILE_LENGTH];
 
 static void child_handler(int signum)
 {
@@ -178,117 +160,6 @@ static int look_up_uart_speed(long int s)
        }
 }
 
-static pid_t daemonize(const char *lockfile, char *tty, char *name)
-{
-       pid_t pid, sid, parent;
-       int lfp = -1;
-       FILE *pFile;
-       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 five 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 */
-       pFile = freopen("/dev/null", "r", stdin);
-       pFile = freopen("/dev/null", "w", stdout);
-       pFile = 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;
@@ -309,7 +180,6 @@ int main(int argc, char *argv[])
        int flow_type = FLOW_NONE;
        char *btr = NULL;
        int run_as_daemon = 1;
-       pid_t parent_pid = 0;
        char *pch;
        int ldisc = LDISC_N_SLCAN;
        int fd;
@@ -388,8 +258,12 @@ int main(int argc, char *argv[])
        syslog(LOG_INFO, "starting on TTY device %s", ttypath);
 
        /* Daemonize */
-       if (run_as_daemon)
-               parent_pid = daemonize("/var/lock/" DAEMON_NAME, tty, name);
+       if (run_as_daemon) {
+               if (daemon(0, 0)) {
+                       syslog(LOG_ERR, "failed to daemonize");
+                       exit(EXIT_FAILURE);
+               }
+       }
        else {
                /* Trap signals that we expect to receive */
                signal(SIGINT, child_handler);
@@ -492,8 +366,6 @@ int main(int argc, char *argv[])
                        close(s);
                }       
        }
-       if (parent_pid > 0)
-               kill(parent_pid, SIGUSR1);
 
        /* The Big Loop */
        while (slcand_running)
@@ -520,10 +392,6 @@ int main(int argc, char *argv[])
        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();