Handle boundary cases more correctly; mblen(s, 0) and mbtowc(NULL, s, 0)

return -1 regardless of what s points to, mbtowc(&w, s, 1) sets w to a
null wide character when s points to a null byte. This seems to be closer
to what most other implementations do, but the C99 standard contradicts
itself for these cases.

2 files changed, 6 insertions, 8 deletions

diff --git a/lib/libc/locale/mblen.c b/lib/libc/locale/mblen.c
index a54e051..ad5edb3 100644
--- a/lib/libc/locale/mblen.c
+++ b/lib/libc/locale/mblen.c
@@ -47,13 +47,12 @@ mblen(const char *s, size_t n)
 {
 	const char *e;
 
-	if (s == NULL || *s == '\0')
+	if (s == NULL)
 		/* No support for state dependent encodings. */
 		return (0);	
-
 	if (sgetrune(s, n, &e) == _INVALID_RUNE) {
 		errno = EILSEQ;
-		return (s - e);
+		return (-1);
 	}
-	return (e - s);
+	return (*s == '\0' ? 0 : e - s);
 }
diff --git a/lib/libc/locale/mbtowc.c b/lib/libc/locale/mbtowc.c
index a690bec..27bebcf 100644
--- a/lib/libc/locale/mbtowc.c
+++ b/lib/libc/locale/mbtowc.c
@@ -48,15 +48,14 @@ mbtowc(wchar_t * __restrict pwc, const char * __restrict s, size_t n)
 	const char *e;
 	rune_t r;
 
-	if (s == NULL || *s == '\0')
+	if (s == NULL)
 		/* No support for state dependent encodings. */
 		return (0);	
-
 	if ((r = sgetrune(s, n, &e)) == _INVALID_RUNE) {
 		errno = EILSEQ;
-		return (s - e);
+		return (-1);
 	}
 	if (pwc != NULL)
 		*pwc = r;
-	return (e - s);
+	return (r == 0 ? 0 : e - s);
 }