cu: make the cu tool can work with SIGNAL disabled

The core functionality of the cu tool does not rely on
signal features. Therefore, we can isolate the signal-related
implementations to ensure that most functions of the
cu tool remain operational even when signals are disabled.

Signed-off-by: guoshichao <[email protected]>

Author: extinguish

system/cu/cu_main.c

@@ -153,11 +153,13 @@ static FAR void *cu_listener(FAR void *parameter)
   return NULL;
 }
 
+#ifndef CONFIG_DISABLE_SIGNALS
 static void cu_exit(int signo, FAR siginfo_t *siginfo, FAR void *context)
 {
   FAR struct cu_globals_s *cu = siginfo->si_user;
   cu->force_exit = true;
 }
+#endif
 
 #ifdef CONFIG_SERIAL_TERMIOS
 static int set_termios(FAR struct cu_globals_s *cu, int rate,
@@ -305,7 +307,9 @@ static int cu_cmd(FAR struct cu_globals_s *cu, char bcmd)
 int main(int argc, FAR char *argv[])
 {
   pthread_attr_t attr;
+#ifndef CONFIG_DISABLE_SIGNALS
   struct sigaction sa;
+#endif
   struct cu_globals_s cu;
   FAR const char *devname = CONFIG_SYSTEM_CUTERM_DEFAULT_DEVICE;
 #ifdef CONFIG_SERIAL_TERMIOS
@@ -325,6 +329,7 @@ int main(int argc, FAR char *argv[])
   memset(&cu, 0, sizeof(struct cu_globals_s));
   cu.escape = '~';
 
+#ifndef CONFIG_DISABLE_SIGNALS
   /* Install signal handlers */
 
   memset(&sa, 0, sizeof(sa));
@@ -337,6 +342,7 @@ int main(int argc, FAR char *argv[])
                errno);
       return EXIT_FAILURE;
     }
+#endif
 
   optind = 0;   /* Global that needs to be reset in FLAT mode */
   while ((option = getopt(argc, argv, "l:s:ceE:fho?")) != ERROR)