Previously, vfscanf()'s wide character processing functions were

reading wide characters manually.  With this change, they now use
fgetwc().  To make this work, we use an internal version of fgetwc()
with a few extensions: it takes an mbstate * because non-wide streams
don't have a built-in mbstate, and it indicates the number of bytes
read.

vfscanf() now resembles vfwscanf() more closely.  Minor functional
improvements include working xlocale support in vfscanf(), setting the
stream error indicator on encoding errors, and proper handling of
shift-based encodings.  (Actually, making shift-based encodings work
with non-wide streams is hopeless, but the implementation now matches
the broken specification.)

3 files changed, 83 insertions, 150 deletions

diff --git a/lib/libc/stdio/fgetwc.c b/lib/libc/stdio/fgetwc.c
index 0e87753..52bc988 100644
--- a/lib/libc/stdio/fgetwc.c
+++ b/lib/libc/stdio/fgetwc.c
@@ -59,6 +59,7 @@ fgetwc_l(FILE *fp, locale_t locale)
 
 	return (r);
 }
+
 wint_t
 fgetwc(FILE *fp)
 {
@@ -66,40 +67,45 @@ fgetwc(FILE *fp)
 }
 
 /*
- * Non-MT-safe version.
+ * Internal (non-MPSAFE) version of fgetwc().  This version takes an
+ * mbstate_t argument specifying the initial conversion state.  For
+ * wide streams, this should always be fp->_mbstate.  On return, *nread
+ * is set to the number of bytes read.
  */
-wint_t
-__fgetwc(FILE *fp, locale_t locale)
+wint_t 
+__fgetwc_mbs(FILE *fp, mbstate_t *mbs, int *nread, locale_t locale)
 {
 	wchar_t wc;
 	size_t nconv;
 	struct xlocale_ctype *l = XLOCALE_CTYPE(locale);
 
-	if (fp->_r <= 0 && __srefill(fp))
+	if (fp->_r <= 0 && __srefill(fp)) {
+		*nread = 0;
 		return (WEOF);
+	}
 	if (MB_CUR_MAX == 1) {
 		/* Fast path for single-byte encodings. */
 		wc = *fp->_p++;
 		fp->_r--;
+		*nread = 1;
 		return (wc);
 	}
+	*nread = 0;
 	do {
-		nconv = l->__mbrtowc(&wc, fp->_p, fp->_r, &fp->_mbstate);
+		nconv = l->__mbrtowc(&wc, fp->_p, fp->_r, mbs);
 		if (nconv == (size_t)-1)
 			break;
 		else if (nconv == (size_t)-2)
 			continue;
 		else if (nconv == 0) {
-			/*
-			 * Assume that the only valid representation of
-			 * the null wide character is a single null byte.
-			 */
 			fp->_p++;
 			fp->_r--;
+			(*nread)++;
 			return (L'\0');
 		} else {
 			fp->_p += nconv;
 			fp->_r -= nconv;
+			*nread += nconv;
 			return (wc);
 		}
 	} while (__srefill(fp) == 0);
diff --git a/lib/libc/stdio/local.h b/lib/libc/stdio/local.h
index 8b37f0d..7168f62 100644
--- a/lib/libc/stdio/local.h
+++ b/lib/libc/stdio/local.h
@@ -56,7 +56,7 @@ extern int	_ftello(FILE *, fpos_t *);
 extern int	_fseeko(FILE *, off_t, int, int);
 extern int	__fflush(FILE *fp);
 extern void	__fcloseall(void);
-extern wint_t	__fgetwc(FILE *, locale_t);
+extern wint_t	__fgetwc_mbs(FILE *, mbstate_t *, int *, locale_t);
 extern wint_t	__fputwc(wchar_t, FILE *, locale_t);
 extern int	__sflush(FILE *);
 extern FILE	*__sfp(void);
@@ -85,6 +85,13 @@ extern size_t	__fread(void * __restrict buf, size_t size, size_t count,
 		FILE * __restrict fp);
 extern int	__sdidinit;
 
+static inline wint_t
+__fgetwc(FILE *fp, locale_t locale)
+{
+	int nread;
+
+	return (__fgetwc_mbs(fp, &fp->_mbstate, &nread, locale));
+}
 
 /*
  * Prepare the given FILE for writing, and return 0 iff it
diff --git a/lib/libc/stdio/vfscanf.c b/lib/libc/stdio/vfscanf.c
index 6a6b19c..4fe40e3 100644
--- a/lib/libc/stdio/vfscanf.c
+++ b/lib/libc/stdio/vfscanf.c
@@ -127,9 +127,8 @@ static const mbstate_t initial_mbs;
 static __inline int
 convert_char(FILE *fp, char * __restrict p, int width)
 {
-	int n, nread;
+	int n;
 
-	nread = 0;
 	if (p == SUPPRESS_PTR) {
 		size_t sum = 0;
 		for (;;) {
@@ -149,59 +148,34 @@ convert_char(FILE *fp, char * __restrict p, int width)
 				break;
 			}
 		}
-		nread += sum;
+		return (sum);
 	} else {
 		size_t r = __fread(p, 1, width, fp);
 		
 		if (r == 0)
 			return (-1);
-		nread += r;
+		return (r);
 	}
-	return (nread);
 }
 
 static __inline int
-convert_wchar(FILE *fp, wchar_t *wcp, int width)
+convert_wchar(FILE *fp, wchar_t *wcp, int width, locale_t locale)
 {
 	mbstate_t mbs;
-	size_t nconv;
 	int n, nread;
-	char buf[MB_CUR_MAX];
+	wint_t wi;
 
-	nread = 0;
+	mbs = initial_mbs;
 	n = 0;
-	while (width != 0) {
-		if (n == MB_CUR_MAX) {
-			fp->_flags |= __SERR;
-			return (-1);
-		}
-		buf[n++] = *fp->_p;
-		fp->_p++;
-		fp->_r--;
-		mbs = initial_mbs;
-		nconv = mbrtowc(wcp, buf, n, &mbs);
-		if (nconv == (size_t)-1) {
-			fp->_flags |= __SERR;
-			return (-1);
-		}
-		if (nconv == 0 && wcp != SUPPRESS_PTR)
-			*wcp = L'\0';
-		if (nconv != (size_t)-2) {
-			nread += n;
-			width--;
-			if (wcp != SUPPRESS_PTR)
-				wcp++;
-			n = 0;
-		}
-		if (fp->_r <= 0 && __srefill(fp)) {
-			if (n != 0) {
-				fp->_flags |= __SERR;
-				return (-1);
-			}
-			break;
-		}
+	while (width-- != 0 &&
+	    (wi = __fgetwc_mbs(fp, &mbs, &nread, locale)) != WEOF) {
+		if (wcp != SUPPRESS_PTR)
+			*wcp++ = (wchar_t)wi;
+		n += nread;
 	}
-	return (nread);
+	if (n == 0)
+		return (-1);
+	return (n);
 }
 
 static __inline int
@@ -244,63 +218,34 @@ convert_ccl(FILE *fp, char * __restrict p, int width, const char *ccltab)
 }
 
 static __inline int
-convert_wccl(FILE *fp, wchar_t *wcp, int width, const char *ccltab)
+convert_wccl(FILE *fp, wchar_t *wcp, int width, const char *ccltab,
+    locale_t locale)
 {
 	mbstate_t mbs;
-	wchar_t twc;
-	int n, nchars, nconv;
-	char buf[MB_CUR_MAX];
+	wint_t wi;
+	int n, nread;
 
-	if (wcp == SUPPRESS_PTR)
-		wcp = &twc;
+	mbs = initial_mbs;
 	n = 0;
-	nchars = 0;
-	while (width != 0) {
-		if (n == MB_CUR_MAX) {
-			fp->_flags |= __SERR;
-			return (-1);
-		}
-		buf[n++] = *fp->_p;
-		fp->_p++;
-		fp->_r--;
-		mbs = initial_mbs;
-		nconv = mbrtowc(wcp, buf, n, &mbs);
-		if (nconv == (size_t)-1) {
-			fp->_flags |= __SERR;
-			return (-1);
-		}
-		if (nconv == 0)
-			*wcp = L'\0';
-		if (nconv != (size_t)-2) {
-			if (wctob(*wcp) != EOF && !ccltab[wctob(*wcp)]) {
-				while (n != 0) {
-					n--;
-					__ungetc(buf[n], fp);
-				}
-				break;
-			}
-			width--;
-			if (wcp != &twc)
-				wcp++;
-			nchars++;
-			n = 0;
-		}
-		if (fp->_r <= 0 && __srefill(fp)) {
-			if (n != 0) {
-				fp->_flags |= __SERR;
-				return (-1);
-			}
-			break;
+	if (wcp == SUPPRESS_PTR) {
+		while ((wi = __fgetwc_mbs(fp, &mbs, &nread, locale)) != WEOF &&
+		    width-- != 0 && ccltab[wctob(wi)])
+			n += nread;
+		if (wi != WEOF)
+			__ungetwc(wi, fp, __get_locale());
+	} else {
+		while ((wi = __fgetwc_mbs(fp, &mbs, &nread, locale)) != WEOF &&
+		    width-- != 0 && ccltab[wctob(wi)]) {
+			*wcp++ = (wchar_t)wi;
+			n += nread;
 		}
+		if (wi != WEOF)
+			__ungetwc(wi, fp, __get_locale());
+		if (n == 0)
+			return (0);
+		*wcp = 0;
 	}
-	if (n != 0) {
-		fp->_flags |= __SERR;
-		return (-1);
-	}
-	if (nchars == 0)
-		return (0);
-	*wcp = L'\0';
-	return (nchars);
+	return (n);
 }
 
 static __inline int
@@ -335,56 +280,31 @@ convert_string(FILE *fp, char * __restrict p, int width)
 }
 
 static __inline int
-convert_wstring(FILE *fp, wchar_t *wcp, int width)
+convert_wstring(FILE *fp, wchar_t *wcp, int width, locale_t locale)
 {
 	mbstate_t mbs;
-	wchar_t twc;
-	int n, nconv, nread;
-	char buf[MB_CUR_MAX];
-
-	if (wcp == SUPPRESS_PTR)
-		wcp = &twc;
-	n = nread = 0;
-	while (!isspace(*fp->_p) && width != 0) {
-		if (n == MB_CUR_MAX) {
-			fp->_flags |= __SERR;
-			return (-1);
-		}
-		buf[n++] = *fp->_p;
-		fp->_p++;
-		fp->_r--;
-		mbs = initial_mbs;
-		nconv = mbrtowc(wcp, buf, n, &mbs);
-		if (nconv == (size_t)-1) {
-			fp->_flags |= __SERR;
-			return (-1);
-		}
-		if (nconv == 0)
-			*wcp = L'\0';
-		if (nconv != (size_t)-2) {
-			if (iswspace(*wcp)) {
-				while (n != 0) {
-					n--;
-					__ungetc(buf[n], fp);
-				}
-				break;
-			}
-			nread += n;
-			width--;
-			if (wcp != &twc)
-				wcp++;
-			n = 0;
-		}
-		if (fp->_r <= 0 && __srefill(fp)) {
-			if (n != 0) {
-				fp->_flags |= __SERR;
-				return (-1);
-			}
-			break;
+	wint_t wi;
+	int n, nread;
+
+	mbs = initial_mbs;
+	n = 0;
+	if (wcp == SUPPRESS_PTR) {
+		while ((wi = __fgetwc_mbs(fp, &mbs, &nread, locale)) != WEOF &&
+		    width-- != 0 && !iswspace(wi))
+			n += nread;
+		if (wi != WEOF)
+			__ungetwc(wi, fp, __get_locale());
+	} else {
+		while ((wi = __fgetwc_mbs(fp, &mbs, &nread, locale)) != WEOF &&
+		    width-- != 0 && !iswspace(wi)) {
+			*wcp++ = (wchar_t)wi;
+			n += nread;
 		}
+		if (wi != WEOF)
+			__ungetwc(wi, fp, __get_locale());
+		*wcp = '\0';
 	}
-	*wcp = L'\0';
-	return (nread);
+	return (n);
 }
 
 /*
@@ -766,7 +686,7 @@ literal:
 				width = 1;
 			if (flags & LONG) {
 				nr = convert_wchar(fp, GETARG(wchar_t *),
-				    width);
+				    width, locale);
 			} else {
 				nr = convert_char(fp, GETARG(char *), width);
 			}
@@ -780,7 +700,7 @@ literal:
 				width = (size_t)~0;	/* `infinity' */
 			if (flags & LONG) {
 				nr = convert_wccl(fp, GETARG(wchar_t *), width,
-				    ccltab);
+				    ccltab, locale);
 			} else {
 				nr = convert_ccl(fp, GETARG(char *), width,
 				    ccltab);
@@ -799,7 +719,7 @@ literal:
 				width = (size_t)~0;
 			if (flags & LONG) {
 				nr = convert_wstring(fp, GETARG(wchar_t *),
-				    width);
+				    width, locale);
 			} else {
 				nr = convert_string(fp, GETARG(char *), width);
 			}