commit 59936c7d972587a47d61161279bb8e8abc0b02f3
from: NRK <nrk@disroot.org>
via: Hiltjo Posthuma <hiltjo@codemadness.org>
date: Sun Jul 14 09:42:58 2024 UTC

render invalid utf8 sequences as U+FFFD

previously drw_text would do the width calculations as if
invalid utf8 sequences were replaced with U+FFFD but would pass
the invalid utf8 sequence to xft to render where xft would just
cut it off at the first invalid byte.

this change makes invalid utf8 render as U+FFFD and avoids
sending invalid sequences to xft. the following can be used to
check the behavior before and after the patch:

	$ printf "0\xef1234567\ntest" | dmenu

Ref: https://lists.suckless.org/dev/2407/35646.html

commit - 51e32d49b56c86cd288c64fccf6cd765547781b9
commit + 59936c7d972587a47d61161279bb8e8abc0b02f3
blob - eb71da7f08e52722b11c70faf1a486bed2e59bb1
blob + f151ae5e2780f77aaad53ab9d7255efe9e981311
--- drw.c
+++ drw.c
@@ -237,7 +237,8 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsig
 	XftResult result;
 	int charexists = 0, overflow = 0;
 	/* keep track of a couple codepoints for which we have no match. */
-	static unsigned int nomatches[128], ellipsis_width;
+	static unsigned int nomatches[128], ellipsis_width, invalid_width;
+	static const char invalid[] = "�";
 
 	if (!drw || (render && (!drw->scheme || !w)) || !text || !drw->fonts)
 		return 0;
@@ -257,6 +258,10 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsig
 	usedfont = drw->fonts;
 	if (!ellipsis_width && render)
 		ellipsis_width = drw_fontset_getwidth(drw, "...");
+	if (!invalid_width) {
+		invalid_width = -1; /* stop infinite recursion */
+		invalid_width = drw_fontset_getwidth(drw, invalid);
+	}
 	while (1) {
 		ew = ellipsis_len = utf8err = utf8charlen = utf8strlen = 0;
 		utf8str = text;
@@ -284,9 +289,9 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsig
 						else
 							utf8strlen = ellipsis_len;
 					} else if (curfont == usedfont) {
-						utf8strlen += utf8charlen;
 						text += utf8charlen;
-						ew += tmpw;
+						utf8strlen += utf8err ? 0 : utf8charlen;
+						ew += utf8err ? 0 : tmpw;
 					} else {
 						nextfont = curfont;
 					}
@@ -294,7 +299,7 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsig
 				}
 			}
 
-			if (overflow || !charexists || nextfont)
+			if (overflow || !charexists || nextfont || utf8err)
 				break;
 			else
 				charexists = 0;
@@ -309,6 +314,12 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsig
 			x += ew;
 			w -= ew;
 		}
+		if (utf8err && (!render || invalid_width < w)) {
+			if (render)
+				drw_text(drw, x, y, w, h, 0, invalid, invert);
+			x += invalid_width;
+			w -= invalid_width;
+		}
 		if (render && overflow)
 			drw_text(drw, ellipsis_x, y, ellipsis_w, h, 0, "...", invert);