commit 8211e36d281990a39db1853bcd454ac59e53d521
from: Hiltjo Posthuma <hiltjo@codemadness.org>
date: Sat May  9 12:07:52 2020 UTC

fix for incorrect (partial) written sequences when libc wcwidth() == -1

Fix an issue with incorrect (partial) written sequences when libc wcwidth() ==
-1. The sequence is updated to on wcwidth(u) == -1:

	c = "\357\277\275"

but len isn't.

A way to reproduce in practise:

* st -o dump.txt
* In the terminal: printf '\xcd\xb8'
- This is codepoint 888, on OpenBSD it reports wcwidth() == -1.
- Quit the terminal.
- Look in dump.txt (partial written sequence of "UTF_INVALID").

This was introduced in:

"	commit 11625c7166b7e4dad414606227acec2de1c36464
	Author: czarkoff@gmail.com <czarkoff@gmail.com>
	Date:   Tue Oct 28 12:55:28 2014 +0100

	    Replace character with U+FFFD if wcwidth() is -1

	    Helpful when new Unicode codepoints are not recognized by libc."

Change:

Remove setting the sequence. If this happens to break something, another
solution could be setting len = 3 for the sequence.

commit - 87545c612e8ab6e7cd1ef38e2355d0cb86df79f2
commit + 8211e36d281990a39db1853bcd454ac59e53d521
blob - c161497638ca2c6ba919b556f77f77ad3638f8b3
blob + 5d4054f619f6646ffe5db2d5768cfbddf6254a2d
--- st.c
+++ st.c
@@ -2312,10 +2312,8 @@ tputc(Rune u)
 		width = len = 1;
 	} else {
 		len = utf8encode(u, c);
-		if (!control && (width = wcwidth(u)) == -1) {
-			memcpy(c, "\357\277\275", 4); /* UTF_INVALID */
+		if (!control && (width = wcwidth(u)) == -1)
 			width = 1;
-		}
 	}
 
 	if (IS_SET(MODE_PRINT))