ignore C1 control characters in UTF-8 mode

Ignore processing and printing C1 control characters in UTF-8 mode.
These are in the range: 0x80 - 0x9f.

By default in st the mode is set to UTF-8.

This matches more the behaviour of xterm with the options -u8 or +u8 also.
Also see the xterm resource "allowC1Printable".

Let me know if this breaks something, in most cases I don't think so.

As usual a very good reference is:
https://invisible-island.net/xterm/ctlseqs/ctlseqs.html

1 files changed, 3 insertions, 0 deletions

diff --git a/st.c b/st.c
index 49357cc..134e724 100644
--- a/st.c
+++ b/st.c
@@ -2422,6 +2422,9 @@ check_control_code:
          * they must not cause conflicts with sequences.
          */
         if (control) {
+                /* in UTF-8 mode ignore handling C1 control characters */
+                if (IS_SET(MODE_UTF8) && ISCONTROLC1(u))
+                        return;
                 tcontrolcode(u);
                 /*
                  * control codes are not shown ever