--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/compat/unvis.c	Wed Apr 01 14:57:57 2015 +0200
@@ -0,0 +1,290 @@
+/*	$OpenBSD: unvis.c,v 1.17 2015/09/13 11:32:51 guenther Exp $ */
+/*-
+ * Copyright (c) 1989, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <ctype.h>
+
+#include "pws-compat.h"
+#include "vis.h"
+
+/*
+ * decode driven by state machine
+ */
+#define	S_GROUND	0	/* haven't seen escape char */
+#define	S_START		1	/* start decoding special sequence */
+#define	S_META		2	/* metachar started (M) */
+#define	S_META1		3	/* metachar more, regular char (-) */
+#define	S_CTRL		4	/* control char started (^) */
+#define	S_OCTAL2	5	/* octal digit 2 */
+#define	S_OCTAL3	6	/* octal digit 3 */
+
+#define	isoctal(c)	(((u_char)(c)) >= '0' && ((u_char)(c)) <= '7')
+
+typedef unsigned int u_int;
+typedef unsigned char u_char;
+
+/*
+ * unvis - decode characters previously encoded by vis
+ */
+int
+unvis(char *cp, char c, int *astate, int flag)
+{
+
+	if (flag & UNVIS_END) {
+		if (*astate == S_OCTAL2 || *astate == S_OCTAL3) {
+			*astate = S_GROUND;
+			return (UNVIS_VALID);
+		} 
+		return (*astate == S_GROUND ? UNVIS_NOCHAR : UNVIS_SYNBAD);
+	}
+
+	switch (*astate) {
+
+	case S_GROUND:
+		*cp = 0;
+		if (c == '\\') {
+			*astate = S_START;
+			return (0);
+		} 
+		*cp = c;
+		return (UNVIS_VALID);
+
+	case S_START:
+		switch(c) {
+		case '-':
+			*cp = 0;
+			*astate = S_GROUND;
+			return (0);
+		case '\\':
+		case '"':
+			*cp = c;
+			*astate = S_GROUND;
+			return (UNVIS_VALID);
+		case '0': case '1': case '2': case '3':
+		case '4': case '5': case '6': case '7':
+			*cp = (c - '0');
+			*astate = S_OCTAL2;
+			return (0);
+		case 'M':
+			*cp = (char) 0200;
+			*astate = S_META;
+			return (0);
+		case '^':
+			*astate = S_CTRL;
+			return (0);
+		case 'n':
+			*cp = '\n';
+			*astate = S_GROUND;
+			return (UNVIS_VALID);
+		case 'r':
+			*cp = '\r';
+			*astate = S_GROUND;
+			return (UNVIS_VALID);
+		case 'b':
+			*cp = '\b';
+			*astate = S_GROUND;
+			return (UNVIS_VALID);
+		case 'a':
+			*cp = '\007';
+			*astate = S_GROUND;
+			return (UNVIS_VALID);
+		case 'v':
+			*cp = '\v';
+			*astate = S_GROUND;
+			return (UNVIS_VALID);
+		case 't':
+			*cp = '\t';
+			*astate = S_GROUND;
+			return (UNVIS_VALID);
+		case 'f':
+			*cp = '\f';
+			*astate = S_GROUND;
+			return (UNVIS_VALID);
+		case 's':
+			*cp = ' ';
+			*astate = S_GROUND;
+			return (UNVIS_VALID);
+		case 'E':
+			*cp = '\033';
+			*astate = S_GROUND;
+			return (UNVIS_VALID);
+		case '\n':
+			/*
+			 * hidden newline
+			 */
+			*astate = S_GROUND;
+			return (UNVIS_NOCHAR);
+		case '$':
+			/*
+			 * hidden marker
+			 */
+			*astate = S_GROUND;
+			return (UNVIS_NOCHAR);
+		}
+		*astate = S_GROUND;
+		return (UNVIS_SYNBAD);
+		 
+	case S_META:
+		if (c == '-')
+			*astate = S_META1;
+		else if (c == '^')
+			*astate = S_CTRL;
+		else {
+			*astate = S_GROUND;
+			return (UNVIS_SYNBAD);
+		}
+		return (0);
+		 
+	case S_META1:
+		*astate = S_GROUND;
+		*cp |= c;
+		return (UNVIS_VALID);
+		 
+	case S_CTRL:
+		if (c == '?')
+			*cp |= 0177;
+		else
+			*cp |= c & 037;
+		*astate = S_GROUND;
+		return (UNVIS_VALID);
+
+	case S_OCTAL2:	/* second possible octal digit */
+		if (isoctal(c)) {
+			/* 
+			 * yes - and maybe a third 
+			 */
+			*cp = (*cp << 3) + (c - '0');
+			*astate = S_OCTAL3;	
+			return (0);
+		} 
+		/* 
+		 * no - done with current sequence, push back passed char 
+		 */
+		*astate = S_GROUND;
+		return (UNVIS_VALIDPUSH);
+
+	case S_OCTAL3:	/* third possible octal digit */
+		*astate = S_GROUND;
+		if (isoctal(c)) {
+			*cp = (*cp << 3) + (c - '0');
+			return (UNVIS_VALID);
+		}
+		/*
+		 * we were done, push back passed char
+		 */
+		return (UNVIS_VALIDPUSH);
+
+	default:	
+		/* 
+		 * decoder in unknown state - (probably uninitialized) 
+		 */
+		*astate = S_GROUND;
+		return (UNVIS_SYNBAD);
+	}
+}
+
+/*
+ * strunvis - decode src into dst 
+ *
+ *	Number of chars decoded into dst is returned, -1 on error.
+ *	Dst is null terminated.
+ */
+
+int
+strunvis(char *dst, const char *src)
+{
+	char c;
+	char *start = dst;
+	int state = 0;
+
+	while ((c = *src++)) {
+	again:
+		switch (unvis(dst, c, &state, 0)) {
+		case UNVIS_VALID:
+			dst++;
+			break;
+		case UNVIS_VALIDPUSH:
+			dst++;
+			goto again;
+		case 0:
+		case UNVIS_NOCHAR:
+			break;
+		default:
+			*dst = '\0';
+			return (-1);
+		}
+	}
+	if (unvis(dst, c, &state, UNVIS_END) == UNVIS_VALID)
+		dst++;
+	*dst = '\0';
+	return (dst - start);
+}
+
+ssize_t
+strnunvis(char *dst, const char *src, size_t sz)
+{
+	char c, p;
+	char *start = dst, *end = dst + sz - 1;
+	int state = 0;
+
+	if (sz > 0)
+		*end = '\0';
+	while ((c = *src++)) {
+	again:
+		switch (unvis(&p, c, &state, 0)) {
+		case UNVIS_VALID:
+			if (dst < end)
+				*dst = p;
+			dst++;
+			break;
+		case UNVIS_VALIDPUSH:
+			if (dst < end)
+				*dst = p;
+			dst++;
+			goto again;
+		case 0:
+		case UNVIS_NOCHAR:
+			break;
+		default:
+			if (dst <= end)
+				*dst = '\0';
+			return (-1);
+		}
+	}
+	if (unvis(&p, c, &state, UNVIS_END) == UNVIS_VALID) {
+		if (dst < end)
+			*dst = p;
+		dst++;
+	}
+	if (dst <= end)
+		*dst = '\0';
+	return (dst - start);
+}
+