Ignore 'und-' prefix for in FcLangCompare

See https://bugs.freedesktop.org/show_bug.cgi?id=94551#c54

For example, matching for :lang=und-zsye matches emoji font, but searching
for :lang=und-xyz wouldn't match an emoji font anymore.  Neither does :lang-und.

1 files changed, 20 insertions, 3 deletions

diff --git a/src/fclang.c b/src/fclang.c
index 8418b46..1eee8ef 100644
--- a/src/fclang.c
+++ b/src/fclang.c
@@ -351,6 +351,13 @@ FcLangCompare (const FcChar8 *s1, const FcChar8 *s2)
 {
     FcChar8	    c1, c2;
     FcLangResult    result = FcLangDifferentLang;
+    FcChar8	   *s1_orig = s1;
+    FcBool	    is_und;
+
+    is_und = FcToLower (s1[0]) == 'u' &&
+	     FcToLower (s1[1]) == 'n' &&
+	     FcToLower (s1[2]) == 'd' &&
+	     FcLangEnd (s1[3]);
 
     for (;;)
     {
@@ -361,14 +368,24 @@ FcLangCompare (const FcChar8 *s1, const FcChar8 *s2)
 	c2 = FcToLower (c2);
 	if (c1 != c2)
 	{
-	    if (FcLangEnd (c1) && FcLangEnd (c2))
+	    if (!is_und && FcLangEnd (c1) && FcLangEnd (c2))
 		result = FcLangDifferentTerritory;
 	    return result;
 	}
 	else if (!c1)
-	    return FcLangEqual;
+	{
+	    return is_und ? result : FcLangEqual;
+	}
 	else if (c1 == '-')
-	    result = FcLangDifferentTerritory;
+	{
+	    if (!is_und)
+		result = FcLangDifferentTerritory;
+	}
+
+	/* If we parsed past "und-", then do not consider it undefined anymore,
+	 * as there's *something* specified. */
+	if (is_und && s1 - s1_orig == 4)
+	    is_und = FcFalse;
     }
 }