X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fmultibyte%2Fmbtowc.c;h=c191bb038bbfdb05a81daf64c732de3b43b40424;hb=c5f4b2dfea320356f69445dc1adf8f73596a3c36;hp=bdcaeb3ce6296f9a2a9659a722bb331342137825;hpb=0b44a0315b47dd8eced9f3b7f31580cf14bbfc01;p=musl

diff --git a/src/multibyte/mbtowc.c b/src/multibyte/mbtowc.c
index bdcaeb3c..c191bb03 100644
--- a/src/multibyte/mbtowc.c
+++ b/src/multibyte/mbtowc.c
@@ -1,19 +1,47 @@
-/* 
- * This code was written by Rich Felker in 2010; no copyright is claimed.
- * This code is in the public domain. Attribution is appreciated but
- * unnecessary.
- */
-
 #include <stdlib.h>
-#include <inttypes.h>
 #include <wchar.h>
 #include <errno.h>
-
 #include "internal.h"
 
-int mbtowc(wchar_t *wc, const char *s, size_t n)
+int mbtowc(wchar_t *restrict wc, const char *restrict src, size_t n)
 {
-	mbstate_t st = { 0 };
-	n = mbrtowc(wc, s, n, &st);
-	return n+2 ? n : -1;
+	unsigned c;
+	const unsigned char *s = (const void *)src;
+	wchar_t dummy;
+
+	if (!s) return 0;
+	if (!n) goto ilseq;
+	if (!wc) wc = &dummy;
+
+	if (*s < 0x80) return !!(*wc = *s);
+	if (MB_CUR_MAX==1) return (*wc = CODEUNIT(*s)), 1;
+	if (*s-SA > SB-SA) goto ilseq;
+	c = bittab[*s++-SA];
+
+	/* Avoid excessive checks against n: If shifting the state n-1
+	 * times does not clear the high bit, then the value of n is
+	 * insufficient to read a character */
+	if (n<4 && ((c<<(6*n-6)) & (1U<<31))) goto ilseq;
+
+	if (OOB(c,*s)) goto ilseq;
+	c = c<<6 | *s++-0x80;
+	if (!(c&(1U<<31))) {
+		*wc = c;
+		return 2;
+	}
+
+	if (*s-0x80u >= 0x40) goto ilseq;
+	c = c<<6 | *s++-0x80;
+	if (!(c&(1U<<31))) {
+		*wc = c;
+		return 3;
+	}
+
+	if (*s-0x80u >= 0x40) goto ilseq;
+	*wc = c<<6 | *s++-0x80;
+	return 4;
+
+ilseq:
+	errno = EILSEQ;
+	return -1;
 }