--- /usr/src/bin/cat/cat.c	2016-07-22 16:42:11.671288000 +0300
+++ cat.c	2016-08-05 17:34:58.835826000 +0300
@@ -51,11 +51,11 @@
 #ifndef NO_UDOM_SUPPORT
 #include <sys/socket.h>
 #include <sys/un.h>
-#include <errno.h>
 #endif
 
 #include <ctype.h>
 #include <err.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <locale.h>
 #include <stddef.h>
@@ -63,6 +63,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <wchar.h>
+#include <wctype.h>
 
 static int bflag, eflag, lflag, nflag, sflag, tflag, vflag;
 static int rval;
@@ -204,60 +206,119 @@
 static void
 cook_cat(FILE *fp)
 {
-	int ch, gobble, line, prev;
+	int c, oc, gobble, line, saverrno;
+	wint_t ch, och, prev;
 
 	/* Reset EOF condition on stdin. */
 	if (fp == stdin && feof(stdin))
 		clearerr(stdin);
 
+	saverrno = errno;
 	line = gobble = 0;
-	for (prev = '\n'; (ch = getc(fp)) != EOF; prev = ch) {
-		if (prev == '\n') {
+	prev = L'\n';
+again:
+	errno = 0;
+	for (; (ch = getwc(fp)) != WEOF; prev = ch) {
+		if (prev == L'\n') {
 			if (sflag) {
-				if (ch == '\n') {
+				if (ch == L'\n') {
 					if (gobble)
 						continue;
 					gobble = 1;
 				} else
 					gobble = 0;
 			}
-			if (nflag && (!bflag || ch != '\n')) {
+			if (nflag && (!bflag || ch != L'\n')) {
 				(void)fprintf(stdout, "%6d\t", ++line);
 				if (ferror(stdout))
 					break;
 			}
 		}
-		if (ch == '\n') {
+		och = WEOF;
+		if (ch == L'\n') {
 			if (eflag && putchar('$') == EOF)
 				break;
-		} else if (ch == '\t') {
+		} else if (ch == L'\t') {
 			if (tflag) {
 				if (putchar('^') == EOF || putchar('I') == EOF)
 					break;
 				continue;
 			}
 		} else if (vflag) {
-			if (!isascii(ch) && !isprint(ch)) {
+			if (!iswprint(ch)) {
 				if (putchar('M') == EOF || putchar('-') == EOF)
 					break;
+				och = ch;
 				ch = toascii(ch);
 			}
-			if (iscntrl(ch)) {
+			if (iswcntrl(ch)) {
+				if (och != WEOF) {
+					och = ch;
+					ch = toascii(ch);
+				}
 				if (putchar('^') == EOF ||
-				    putchar(ch == '\177' ? '?' :
-				    ch | 0100) == EOF)
+				    putwchar(ch == L'\177' ? L'?' :
+				    ch | 0100) == WEOF)
 					break;
+				ch = och;
 				continue;
 			}
 		}
-		if (putchar(ch) == EOF)
+		if (putwchar(ch) == WEOF)
 			break;
+		if (och != WEOF)
+			ch = och;
 	}
+	if (!ferror(stdout) && !feof(fp) && ferror(fp) && errno == EILSEQ) {
+		if ((c = getc(fp)) != EOF) {
+			if (prev == L'\n') {
+				if (sflag)
+					gobble = 0;
+				if (nflag) {
+					(void)fprintf(stdout, "%6d\t", ++line);
+					if (ferror(stdout))
+						goto err;
+				}
+			}
+			oc = EOF;
+			if (vflag) {
+				if (c >= ' ' && c != '\177') {
+					if (putchar('M') == EOF || putchar('-') == EOF)
+						goto err;
+					oc = c;
+					c = toascii(c);
+				}
+				if (c < ' ' || c == '\177') {
+					if (putchar('^') == EOF ||
+					    putchar(c == '\177' ? '?' :
+					    c | 0100) == EOF)
+						goto err;
+					if (oc != EOF)
+						c = oc;
+					prev = c;
+					clearerr(fp);
+					goto again;
+				}
+			}
+			if (putchar(c) == EOF)
+				goto err;
+			if (oc != EOF)
+				c = oc;
+			prev = c;
+			clearerr(fp);
+			goto again;
+		}
+	}
+err:
 	if (ferror(fp)) {
-		warn("%s", filename);
-		rval = 1;
+		if (errno != EILSEQ) {
+			warn("%s", filename);
+			rval = 1;
+		}
 		clearerr(fp);
 	}
+	if (errno == 0)
+		errno = saverrno;
 	if (ferror(stdout))
 		err(1, "stdout");
 }