Quit from non-interactive mode using ctrl-c

When piping to tio it will automatically enter "non-interactive" mode
which means it will not react to any input key sequences but simple read
the input stream and write it to the tty device.

This also means that ctrl-t q can not be used to quit and so tio would
hang forever when used in non-interactive mode.

This change allows to send the standard termination signal by pressing
ctrl-c on tio in non-interactive mode to make it quit.

src/main.c

@@ -96,6 +96,10 @@ int main(int argc, char *argv[])
     if (interactive_mode)
     {
         tio_printf("Press ctrl-%c q to quit", option.prefix_key);
+    } else
+    {
+        tio_printf("Non-interactive mode enabled");
+        tio_printf("Press ctrl-c to quit");
     }
 
     /* Open socket */
@@ -105,7 +109,7 @@ int main(int argc, char *argv[])
     }
 
     /* Connect to tty device */
-    if ((option.no_autoconnect) || (!interactive_mode))
+    if (option.no_autoconnect)
     {
         status = tty_connect();
     }

src/signals.c

@@ -27,15 +27,24 @@
 #include "error.h"
 #include "print.h"
 #include "misc.h"
+#include "tty.h"
 
 static void signal_handler(int signum)
 {
-    UNUSED(signum);
+    switch (signum)
-    tio_printf("Received hangup signal!");
+    {
+        case SIGHUP:
+            tio_printf("Received SIGHUP signal!");
+            break;
+        case SIGINT:
+            tio_printf("Received SIGINT signal!");
+            break;
+    }
     exit(EXIT_FAILURE);
 }
 
 void signal_handlers_install(void)
 {
     signal(SIGHUP, signal_handler);
+    signal(SIGINT, signal_handler);
 }

src/tty.c

@@ -586,6 +586,12 @@ void stdout_configure(void)
     /* Reconfigure stdout (RAW configuration) */
     cfmakeraw(&stdout_new);
 
+    /* Allow ^C / SIGINT (to allow termination when piping to tio) */
+    if (!interactive_mode)
+    {
+        stdout_new.c_lflag |= ISIG;
+    }
+
     /* Control characters */
     stdout_new.c_cc[VTIME] = 0; /* Inter-character timer unused */
     stdout_new.c_cc[VMIN]  = 1; /* Blocking read until 1 character received */
@@ -833,6 +839,10 @@ void tty_wait_for_device(void)
     /* Loop until device pops up */
     while (true)
     {
+        if (interactive_mode)
+        {
+            /* In interactive mode, while waiting for tty device, we need to
+             * read from stdin to react on input key commands. */
             if (first)
             {
                 /* Don't wait first time */
@@ -842,7 +852,7 @@ void tty_wait_for_device(void)
             }
             else
             {
-            /* Wait up to 1 second */
+                /* Wait up to 1 second for input */
                 tv.tv_sec = 1;
                 tv.tv_usec = 0;
             }
@@ -879,6 +889,7 @@ void tty_wait_for_device(void)
                 tio_error_printf("select() failed (%s)", strerror(errno));
                 exit(EXIT_FAILURE);
             }
+        }
 
         /* Test for accessible device file */
         status = access(option.tty_device, R_OK);
@@ -893,6 +904,14 @@ void tty_wait_for_device(void)
             tio_printf("Waiting for tty device..");
             last_errno = errno;
         }
+
+        if (!interactive_mode)
+        {
+            /* In non-interactive mode we do not need to handle input key
+             * commands so we simply sleep 1 second between checking for
+             * presence of tty device */
+            sleep(1);
+        }
     }
 }