Reimplement the functionality of fgetrune(), fputrune(), and fungetrune()

here in terms of mbrtowc(), wcrtomb(), and the single-byte I/O functions.
The rune I/O functions are about to become deprecated in favour of the
ones provided by ISO C90 Amd. 1 and C99.

lib/libc/stdio/fgetwc.c

@@ -29,8 +29,8 @@ __FBSDID("$FreeBSD$");
 
 #include "namespace.h"
 #include <errno.h>
-#include <rune.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <wchar.h>
 #include "un-namespace.h"
 #include "libc_private.h"
@@ -39,18 +39,34 @@ __FBSDID("$FreeBSD$");
 wint_t
 fgetwc(FILE *fp)
 {
-	wint_t wc;
-	long r;
+	char buf[MB_LEN_MAX];
+	mbstate_t mbs;
+	size_t n, nconv;
+	int c;
+	wchar_t wc;
 
 	ORIENTLOCK(fp, 1);
 
-	if ((r = fgetrune(fp)) == _INVALID_RUNE) {
-		wc = WEOF;
-		errno = EILSEQ;
-	} else if (r == EOF)
-		wc = WEOF;
-	else
-		wc = (wint_t)r;
+	n = 0;
+	while (n < MB_CUR_MAX) {
+		if ((c = fgetc(fp)) == EOF) {
+			if (n == 0)
+				return (WEOF);
+			break;
+		}
+		buf[n++] = (char)c;
+		memset(&mbs, 0, sizeof(mbs));
+		nconv = mbrtowc(&wc, buf, n, &mbs);
+		if (nconv == n)
+			return (wc);
+		else if (nconv == 0)
+			return (L'\0');
+		else if (nconv == (size_t)-2 || nconv == (size_t)-1)
+			break;
+	}
 
-	return (wc);
+	while (n-- != 0)
+		ungetc((unsigned char)buf[n], fp);
+	errno = EILSEQ;
+	return (WEOF);
 }

lib/libc/stdio/fgetws.c

@@ -29,7 +29,6 @@ __FBSDID("$FreeBSD$");
 
 #include "namespace.h"
 #include <errno.h>
-#include <rune.h>
 #include <stdio.h>
 #include <wchar.h>
 #include "un-namespace.h"
@@ -40,7 +39,7 @@ wchar_t *
 fgetws(wchar_t * __restrict ws, int n, FILE * __restrict fp)
 {
 	wchar_t *wsp;
-	long r;
+	wint_t wc;
 
 	ORIENTLOCK(fp, 1);
 
@@ -50,18 +49,16 @@ fgetws(wchar_t * __restrict ws, int n, FILE * __restrict fp)
 	wsp = ws;
 	while (n-- > 1) {
 		/* XXX Inefficient */
-		if ((r = fgetrune(fp)) == _INVALID_RUNE) {
-			errno = EILSEQ;
+		if ((wc = fgetwc(fp)) == WEOF && errno == EILSEQ)
 			return (NULL);
-		}
-		if (r == EOF) {
+		if (wc == WEOF) {
 			if (wsp == ws)
 				/* EOF/error, no characters read yet. */
 				return (NULL);
 			break;
 		}
-		*wsp++ = (wchar_t)r;
-		if (r == L'\n')
+		*wsp++ = (wchar_t)wc;
+		if (wc == L'\n')
 			break;
 	}
 	*wsp++ = L'\0';

lib/libc/stdio/fputwc.c

@@ -29,8 +29,8 @@ __FBSDID("$FreeBSD$");
 
 #include "namespace.h"
 #include <errno.h>
-#include <rune.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <wchar.h>
 #include "un-namespace.h"
 #include "libc_private.h"
@@ -39,8 +39,19 @@ __FBSDID("$FreeBSD$");
 wint_t
 fputwc(wchar_t wc, FILE *fp)
 {
+	char buf[MB_LEN_MAX];
+	mbstate_t mbs;
+	size_t i, len;
 
 	ORIENTLOCK(fp, 1);
 
-	return (fputrune((rune_t)wc, fp) != EOF ? (wint_t)wc : WEOF);
+	memset(&mbs, 0, sizeof(mbs));
+	if ((len = wcrtomb(buf, wc, &mbs)) == (size_t)-1)
+		return (WEOF);
+
+	for (i = 0; i < len; i++)
+		if (fputc((unsigned char)buf[i], fp) == EOF)
+			return (WEOF);
+
+	return ((wint_t)wc);
 }

lib/libc/stdio/fputws.c

@@ -29,7 +29,6 @@ __FBSDID("$FreeBSD$");
 
 #include "namespace.h"
 #include <errno.h>
-#include <rune.h>
 #include <stdio.h>
 #include <wchar.h>
 #include "un-namespace.h"
@@ -44,7 +43,7 @@ fputws(const wchar_t * __restrict ws, FILE * __restrict fp)
 
 	/* XXX Inefficient */
 	while (*ws != '\0')
-		if (fputrune((rune_t)*ws++, fp) == EOF)
+		if (fputwc(*ws++, fp) == WEOF)
 			return (-1);
 
 	return (0);

lib/libc/stdio/ungetwc.c

@@ -29,8 +29,8 @@ __FBSDID("$FreeBSD$");
 
 #include "namespace.h"
 #include <errno.h>
-#include <rune.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <wchar.h>
 #include "un-namespace.h"
 #include "libc_private.h"
@@ -39,8 +39,21 @@ __FBSDID("$FreeBSD$");
 wint_t
 ungetwc(wint_t wc, FILE *fp)
 {
+	char buf[MB_LEN_MAX];
+	mbstate_t mbs;
+	size_t len;
 
 	ORIENTLOCK(fp, 1);
 
-	return (fungetrune((rune_t)wc, fp) == EOF ? WEOF : wc);
+	if (wc == WEOF)
+		return (WEOF);
+
+	memset(&mbs, 0, sizeof(mbs));
+	if ((len = wcrtomb(buf, wc, &mbs)) == (size_t)-1)
+		return (WEOF);
+	while (len-- != 0)
+		if (ungetc((unsigned char)buf[len], fp) == EOF)
+			return (WEOF);
+
+	return (wc);
 }