Tweak utf8towc() to return -1 earlier sometimes (instead of -2), and add test

program to compare against libc output.

1 files changed, 3 insertions, 6 deletions

diff --git a/lib/lib.c b/lib/lib.c
index c482dcab..a4b7229b 100644
--- a/lib/lib.c
+++ b/lib/lib.c
@@ -345,20 +345,17 @@ int utf8towc(wchar_t *wc, char *str, unsigned len)
   if (len && *str<128) return !!(*wc = *str);
 
   result = first = *(s = str++);
+  if (result<0xc2 || result>0xf4) return -1;
   for (mask = 6; (first&0xc0)==0xc0; mask += 5, first <<= 1) {
-    if (mask>21) return -1;
     if (!--len) return -2;
-    c = *(str++);
-    if ((c&0xc0) != 0x80) return -1;
+    if (((c = *(str++))&0xc0) != 0x80) return -1;
     result = (result<<6)|(c&0x3f);
   }
   result &= (1<<mask)-1;
   c = str-s;
-  if (mask==6) return -1;
 
   // Avoid overlong encodings
-  if (mask==6 || mask>21 || result<(unsigned []){0x80,0x800,0x10000}[c-2])
-    return -1;
+  if (result<(unsigned []){0x80,0x800,0x10000}[c-2]) return -1;
 
   // Limit unicode so it can't encode anything UTF-16 can't.
   if (result>0x10ffff || (result>=0xd800 && result<=0xdfff)) return -1;