udev operation mode; -x and -X options to exit a running instance

In udev mode (-u|--udev) the return value is 0 if another instance is
already running
-x|--exit tells a running instance to exit by sending signal 3 (SIGQUIT)
-X|--force-exit tells a running instance to exit even if devices are
still connected by sending signal 15 (SIGTERM)

1 files changed, 55 insertions, 6 deletions

diff --git a/src/main.c b/src/main.c
index ee633b6..c567a66 100644
--- a/src/main.c
+++ b/src/main.c
@@ -58,6 +58,9 @@ static int verbose = DEBUG_LEVEL;
 static int foreground = 0;
 static int exit_on_no_devices = 0;
 static int drop_privileges = 0;
+static int opt_udev = 0;
+static int opt_exit = 0;
+static int exit_signal = 0;
 
 struct device_info {
         uint32_t device_id;
@@ -1030,6 +1033,10 @@ static void usage()
         printf("\t-f|--foreground           do not daemonize\n");
         printf("\t-e|--exit-on-no-devices   exit if no device is attached\n");
         printf("\t-d|--drop-privileges      drop privileges after startup\n");
+        printf("\t-u|--udev                 udev operation mode\n");
+        printf("\t-x|--exit                 tell a running instance to exit\n");
+        printf("\t-X|--force-exit           tell a running instance to exit, even if\n");
+        printf("\t                          there are still devices connected\n");
         printf("\n");
 }
 
@@ -1041,12 +1048,15 @@ static void parse_opts(int argc, char **argv)
                 {"verbose", 0, NULL, 'v'},
                 {"exit-on-no-devices", 0, NULL, 'e'},
                 {"drop-privileges", 0, NULL, 'd'},
+                {"udev", 0, NULL, 'u'},
+                {"exit", 0, NULL, 'x'},
+                {"force-exit", 0, NULL, 'X'},
                 {NULL, 0, NULL, 0}
         };
         int c;
 
         while (1) {
-                c = getopt_long(argc, argv, "hfved", longopts, (int *) 0);
+                c = getopt_long(argc, argv, "hfveduxX", longopts, (int *) 0);
                 if (c == -1) {
                         break;
                 }
@@ -1067,11 +1077,24 @@ static void parse_opts(int argc, char **argv)
                 case 'd':
                         drop_privileges = 1;
                         break;
+                case 'u':
+                        opt_udev = 1;
+                        break;
+                case 'x':
+                        opt_exit = 1;
+                        exit_signal = SIGQUIT;
+                        break;
+                case 'X':
+                        opt_exit = 1;
+                        exit_signal = SIGTERM;
+                        break;
                 default:
                         usage();
                         exit(2);
                 }
         }
+        if (opt_udev)
+                foreground = 0;
 }
 
 /**
@@ -1141,6 +1164,7 @@ int main(int argc, char **argv)
         int children_capacity = DEFAULT_CHILDREN_CAPACITY;
         int i;
         int result = 0;
+        int exit_val = 0;
         int cnt = 0;
         FILE *lfd = NULL;
         struct flock lock;
@@ -1154,7 +1178,7 @@ int main(int argc, char **argv)
                 openlog("usbmuxd", LOG_PID, 0);
         }
 
-        if (verbose >= 2)
+        if (verbose >= 1)
                 logmsg(LOG_NOTICE, "starting");
 
         // signal(SIGHUP, reload_conf); // none yet
@@ -1173,12 +1197,35 @@ int main(int argc, char **argv)
                 fcntl(fileno(lfd), F_GETLK, &lock);
                 fclose(lfd);
                 if (lock.l_type != F_UNLCK) {
-                        logmsg(LOG_NOTICE,
-                                   "another instance is already running. exiting.");
-                        return -1;
+                        if (opt_exit) {
+                                if (lock.l_pid && !kill(lock.l_pid, 0)) {
+                                        logmsg(LOG_NOTICE, "sending signal %d to instance with pid %d", exit_signal, lock.l_pid);
+                                        if (kill(lock.l_pid, exit_signal) < 0) {
+                                                logmsg(LOG_ERR, "Error: could not deliver signal %d to pid %d", exit_signal, lock.l_pid);
+                                        }
+                                        exit_val = 0;
+                                        goto terminate;
+                                } else {
+                                        logmsg(LOG_ERR, "Error: could not determine pid of the other running instance!");
+                                        exit_val = -1;
+                                        goto terminate;
+                                }
+                        } else {
+                                logmsg(LOG_NOTICE,
+                                           "another instance is already running (pid %d). exiting.", lock.l_pid);
+                                if (!opt_udev) {
+                                        exit_val = -1;
+                                }
+                                goto terminate;
+                        }
                 }
         }
 
+        if (opt_exit) {
+                logmsg(LOG_NOTICE, "no running instance found, none killed. exiting.");
+                goto terminate;
+        }
+
         if (exit_on_no_devices) {
                 if (devices_attached() <= 0) {
                         logmsg(LOG_NOTICE, "no devices attached. exiting.");
@@ -1220,6 +1267,7 @@ int main(int argc, char **argv)
                 lock.l_len = 0;
                 if (fcntl(fileno(lfd), F_SETLK, &lock) == -1) {
                         logmsg(LOG_ERR, "ERROR: lockfile locking failed!");
+                        exit(EXIT_FAILURE);
                 }
         }
         // drop elevated privileges
@@ -1388,8 +1436,9 @@ int main(int argc, char **argv)
                 fclose(lfd);
         }
 
+terminate:
         if (verbose >= 1)
-                logmsg(LOG_NOTICE, "usbmuxd: terminated");
+                logmsg(LOG_NOTICE, "terminated");
         if (!foreground) {
                 closelog();
         }