When running in daemon mode, delay parent exit until device is created

Doing this is somewhat elaborate because cuse_lowlevel_main() when
daemonizing, the parent (the calling thread) calls _exit(0) instead of
returning.

ttynvt.c

@@ -39,6 +39,8 @@ static struct ttynvt_param {
     /* Derived */
     char            host[64];
     unsigned int    port;
+    /* Picked up */
+    int             foreground;
 } ttynvt_param;
 
 typedef struct ttynvt {
@@ -80,6 +82,22 @@ static void _log(int prio, const char *fmt, ...)
     if (ttynvt_param.debug) _log(LOG_DEBUG, __VA_ARGS__)
 
 
+static int _check_dev(void)
+{
+    int             rc;
+    char            dev_nbuf[128];
+    struct stat     st;
+
+    snprintf(dev_nbuf, sizeof(dev_nbuf), "/dev/%s", ttynvt_param.dev_name);
+
+    rc = stat(dev_nbuf, &st);
+
+    DBG("Checking for %s: %d\n", dev_nbuf, rc);
+
+    return rc;
+}
+
+
 static void ttynvt_release(fuse_req_t req, struct fuse_file_info *info)
 {
     ttynvt_t       *tty = (ttynvt_t *) (uintptr_t) info->fh;
@@ -828,6 +846,8 @@ process_arg(void *data, const char *arg, int key, struct fuse_args *outargs)
         print_help();
         return fuse_opt_add_arg(outargs, "-ho");
     default:
+        if (strcmp(arg, "-d") == 0 || strcmp(arg, "-f") == 0)
+            ttynvt_param.foreground = 1;
         return 1;
     }
 }
@@ -839,6 +859,7 @@ int main(int argc, char *argv[])
 
     char            dev_name[128];
     const char     *dev_info_argv[] = { dev_name };
+    pid_t           cpid;
 
     openlog("ttynvt", LOG_PID, LOG_DAEMON);
 
@@ -881,5 +902,41 @@ int main(int argc, char *argv[])
         .flags = CUSE_UNRESTRICTED_IOCTL,
     };
 
+    if (ttynvt_param.foreground)
+    {
         return cuse_lowlevel_main(args.argc, args.argv, &ci, &ttynvt_op, NULL);
     }
+
+    cpid = fork();
+    switch (cpid)
+    {
+    case -1:
+        _log(LOG_ERR, "fork(): %m");
+        return -1;
+
+    case 0:                    /* Child */
+        DBG("Child proceeding...\n");
+        rc = cuse_lowlevel_main(args.argc, args.argv, &ci, &ttynvt_op, NULL);
+        if (rc != 0)
+            _log(LOG_ERR, "ttynvt failed rc=%d", rc);
+        else
+            DBG("Child exited\n");
+        return rc;
+
+    default:                   /* Parent */
+        break;
+    }
+
+    DBG("Parent proceeding (child=%d)...\n", cpid);
+
+    for (rc = 0; rc < 10; rc++)
+    {
+        if (_check_dev() == 0)
+            break;
+        usleep(500000);
+    }
+
+    DBG("Parent exiting\n");
+
+    return 0;
+}