Replace our implementation of the vis(3) and unvis(3) APIs with

NetBSD's.  This output size limited versions of vis and unvis functions
as well as a set of vis variants that allow arbitrary characters to be
specified for encoding.

Finally, MIME Quoted-Printable encoding as described in RFC 2045 is
supported.

5 files changed, 1962 insertions, 0 deletions

diff --git a/contrib/libc-vis/unvis.3 b/contrib/libc-vis/unvis.3
new file mode 100644
index 000000000000..472c49d9be33
--- /dev/null
+++ b/contrib/libc-vis/unvis.3
@@ -0,0 +1,247 @@
+.\"	$NetBSD: unvis.3,v 1.23 2011/03/17 14:06:29 wiz Exp $
+.\"	$FreeBSD$
+.\"
+.\" Copyright (c) 1989, 1991, 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.
+.\"
+.\"     @(#)unvis.3	8.2 (Berkeley) 12/11/93
+.\"
+.Dd March 12, 2011
+.Dt UNVIS 3
+.Os
+.Sh NAME
+.Nm unvis ,
+.Nm strunvis
+.Nd decode a visual representation of characters
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.In vis.h
+.Ft int
+.Fn unvis "char *cp" "int c" "int *astate" "int flag"
+.Ft int
+.Fn strunvis "char *dst" "const char *src"
+.Ft int
+.Fn strnunvis "char *dst" "size_t dlen" "const char *src"
+.Ft int
+.Fn strunvisx "char *dst" "const char *src" "int flag"
+.Ft int
+.Fn strnunvisx "char *dst" "size_t dlen" "const char *src" "int flag"
+.Sh DESCRIPTION
+The
+.Fn unvis ,
+.Fn strunvis
+and
+.Fn strunvisx
+functions
+are used to decode a visual representation of characters, as produced
+by the
+.Xr vis 3
+function, back into
+the original form.
+.Pp
+The
+.Fn unvis
+function is called with successive characters in
+.Ar c
+until a valid sequence is recognized, at which time the decoded
+character is available at the character pointed to by
+.Ar cp .
+.Pp
+The
+.Fn strunvis
+function decodes the characters pointed to by
+.Ar src
+into the buffer pointed to by
+.Ar dst .
+The
+.Fn strunvis
+function simply copies
+.Ar src
+to
+.Ar dst ,
+decoding any escape sequences along the way,
+and returns the number of characters placed into
+.Ar dst ,
+or \-1 if an
+invalid escape sequence was detected.
+The size of
+.Ar dst
+should be equal to the size of
+.Ar src
+(that is, no expansion takes place during decoding).
+.Pp
+The
+.Fn strunvisx
+function does the same as the
+.Fn strunvis
+function,
+but it allows you to add a flag that specifies the style the string
+.Ar src
+is encoded with.
+Currently, the supported flags are:
+.Dv VIS_HTTPSTYLE
+and
+.Dv VIS_MIMESTYLE .
+.Pp
+The
+.Fn unvis
+function implements a state machine that can be used to decode an
+arbitrary stream of bytes.
+All state associated with the bytes being decoded is stored outside the
+.Fn unvis
+function (that is, a pointer to the state is passed in), so
+calls decoding different streams can be freely intermixed.
+To start decoding a stream of bytes, first initialize an integer to zero.
+Call
+.Fn unvis
+with each successive byte, along with a pointer
+to this integer, and a pointer to a destination character.
+The
+.Fn unvis
+function has several return codes that must be handled properly.
+They are:
+.Bl -tag -width UNVIS_VALIDPUSH
+.It Li \&0 (zero)
+Another character is necessary; nothing has been recognized yet.
+.It Dv UNVIS_VALID
+A valid character has been recognized and is available at the location
+pointed to by cp.
+.It Dv UNVIS_VALIDPUSH
+A valid character has been recognized and is available at the location
+pointed to by cp; however, the character currently passed in should
+be passed in again.
+.It Dv UNVIS_NOCHAR
+A valid sequence was detected, but no character was produced.
+This return code is necessary to indicate a logical break between characters.
+.It Dv UNVIS_SYNBAD
+An invalid escape sequence was detected, or the decoder is in an unknown state.
+The decoder is placed into the starting state.
+.El
+.Pp
+When all bytes in the stream have been processed, call
+.Fn unvis
+one more time with flag set to
+.Dv UNVIS_END
+to extract any remaining character (the character passed in is ignored).
+.Pp
+The
+.Ar flag
+argument is also used to specify the encoding style of the source.
+If set to
+.Dv VIS_HTTPSTYLE
+or
+.Dv VIS_HTTP1808 ,
+.Fn unvis
+will decode URI strings as specified in RFC 1808.
+If set to
+.Dv VIS_HTTP1866 ,
+.Fn unvis
+will decode URI strings as specified in RFC 1866.
+If set to
+.Dv VIS_MIMESTYLE ,
+.Fn unvis
+will decode MIME Quoted-Printable strings as specified in RFC 2045.
+If set to
+.Dv VIS_NOESCAPE ,
+.Fn unvis
+will not decode \e quoted characters.
+.Pp
+The following code fragment illustrates a proper use of
+.Fn unvis .
+.Bd -literal -offset indent
+int state = 0;
+char out;
+
+while ((ch = getchar()) != EOF) {
+again:
+	switch(unvis(\*[Am]out, ch, \*[Am]state, 0)) {
+	case 0:
+	case UNVIS_NOCHAR:
+		break;
+	case UNVIS_VALID:
+		(void)putchar(out);
+		break;
+	case UNVIS_VALIDPUSH:
+		(void)putchar(out);
+		goto again;
+	case UNVIS_SYNBAD:
+		errx(EXIT_FAILURE, "Bad character sequence!");
+	}
+}
+if (unvis(\*[Am]out, '\e0', \*[Am]state, UNVIS_END) == UNVIS_VALID)
+	(void)putchar(out);
+.Ed
+.Sh ERRORS
+The functions
+.Fn strunvis ,
+.Fn strnunvis ,
+.Fn strunvisx ,
+and
+.Fn strnunvisx
+will return \-1 on error and set
+.Va errno 
+to:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+An invalid escape sequence was detected, or the decoder is in an unknown state.
+.El
+.Pp
+In addition the functions
+.Fn strnunvis 
+and
+.Fn strnunvisx
+will can also set
+.Va errno
+on error to:
+.Bl -tag -width Er
+.It Bq Er ENOSPC
+Not enough space to perform the conversion.
+.El
+.Sh SEE ALSO
+.Xr unvis 1 ,
+.Xr vis 1 ,
+.Xr vis 3
+.Rs
+.%A R. Fielding
+.%T Relative Uniform Resource Locators
+.%O RFC1808
+.Re
+.Sh HISTORY
+The
+.Fn unvis
+function
+first appeared in
+.Bx 4.4 .
+The
+.Fn strnunvis
+and
+.Fn strnunvisx
+functions appeared in
+.Nx 6.0
+and
+.Fx 10.0 .
diff --git a/contrib/libc-vis/unvis.c b/contrib/libc-vis/unvis.c
new file mode 100644
index 000000000000..d87812acde63
--- /dev/null
+++ b/contrib/libc-vis/unvis.c
@@ -0,0 +1,562 @@
+/*	$NetBSD: unvis.c,v 1.40 2012/12/14 21:31:01 christos 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/cdefs.h>
+#if defined(LIBC_SCCS) && !defined(lint)
+#if 0
+static char sccsid[] = "@(#)unvis.c	8.1 (Berkeley) 6/4/93";
+#else
+__RCSID("$NetBSD: unvis.c,v 1.40 2012/12/14 21:31:01 christos Exp $");
+#endif
+#endif /* LIBC_SCCS and not lint */
+__FBSDID("$FreeBSD$");
+
+#include "namespace.h"
+#include <sys/types.h>
+
+#include <assert.h>
+#include <ctype.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <errno.h>
+#include <vis.h>
+
+#define	_DIAGASSERT(x)	assert(x)
+
+/*
+ * Return the number of elements in a statically-allocated array,
+ * __x.
+ */
+#define	__arraycount(__x)	(sizeof(__x) / sizeof(__x[0]))
+
+#ifdef __weak_alias
+__weak_alias(strnunvisx,_strnunvisx)
+#endif
+
+#if !HAVE_VIS
+/*
+ * 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	S_HEX		7	/* mandatory hex digit */
+#define	S_HEX1		8	/* http hex digit */
+#define	S_HEX2		9	/* http hex digit 2 */
+#define	S_MIME1		10	/* mime hex digit 1 */
+#define	S_MIME2		11	/* mime hex digit 2 */
+#define	S_EATCRNL	12	/* mime eating CRNL */
+#define	S_AMP		13	/* seen & */
+#define	S_NUMBER	14	/* collecting number */
+#define	S_STRING	15	/* collecting string */
+
+#define	isoctal(c)	(((u_char)(c)) >= '0' && ((u_char)(c)) <= '7')
+#define	xtod(c)		(isdigit(c) ? (c - '0') : ((tolower(c) - 'a') + 10))
+#define	XTOD(c)		(isdigit(c) ? (c - '0') : ((c - 'A') + 10))
+
+/*
+ * RFC 1866
+ */
+static const struct nv {
+	const char name[7];
+	uint8_t value;
+} nv[] = {
+	{ "AElig",	198 }, /* capital AE diphthong (ligature)  */
+	{ "Aacute",	193 }, /* capital A, acute accent  */
+	{ "Acirc",	194 }, /* capital A, circumflex accent  */
+	{ "Agrave",	192 }, /* capital A, grave accent  */
+	{ "Aring",	197 }, /* capital A, ring  */
+	{ "Atilde",	195 }, /* capital A, tilde  */
+	{ "Auml",	196 }, /* capital A, dieresis or umlaut mark  */
+	{ "Ccedil",	199 }, /* capital C, cedilla  */
+	{ "ETH",	208 }, /* capital Eth, Icelandic  */
+	{ "Eacute",	201 }, /* capital E, acute accent  */
+	{ "Ecirc",	202 }, /* capital E, circumflex accent  */
+	{ "Egrave",	200 }, /* capital E, grave accent  */
+	{ "Euml",	203 }, /* capital E, dieresis or umlaut mark  */
+	{ "Iacute",	205 }, /* capital I, acute accent  */
+	{ "Icirc",	206 }, /* capital I, circumflex accent  */
+	{ "Igrave",	204 }, /* capital I, grave accent  */
+	{ "Iuml",	207 }, /* capital I, dieresis or umlaut mark  */
+	{ "Ntilde",	209 }, /* capital N, tilde  */
+	{ "Oacute",	211 }, /* capital O, acute accent  */
+	{ "Ocirc",	212 }, /* capital O, circumflex accent  */
+	{ "Ograve",	210 }, /* capital O, grave accent  */
+	{ "Oslash",	216 }, /* capital O, slash  */
+	{ "Otilde",	213 }, /* capital O, tilde  */
+	{ "Ouml",	214 }, /* capital O, dieresis or umlaut mark  */
+	{ "THORN",	222 }, /* capital THORN, Icelandic  */
+	{ "Uacute",	218 }, /* capital U, acute accent  */
+	{ "Ucirc",	219 }, /* capital U, circumflex accent  */
+	{ "Ugrave",	217 }, /* capital U, grave accent  */
+	{ "Uuml",	220 }, /* capital U, dieresis or umlaut mark  */
+	{ "Yacute",	221 }, /* capital Y, acute accent  */
+	{ "aacute",	225 }, /* small a, acute accent  */
+	{ "acirc",	226 }, /* small a, circumflex accent  */
+	{ "acute",	180 }, /* acute accent  */
+	{ "aelig",	230 }, /* small ae diphthong (ligature)  */
+	{ "agrave",	224 }, /* small a, grave accent  */
+	{ "amp",	 38 }, /* ampersand  */
+	{ "aring",	229 }, /* small a, ring  */
+	{ "atilde",	227 }, /* small a, tilde  */
+	{ "auml",	228 }, /* small a, dieresis or umlaut mark  */
+	{ "brvbar",	166 }, /* broken (vertical) bar  */
+	{ "ccedil",	231 }, /* small c, cedilla  */
+	{ "cedil",	184 }, /* cedilla  */
+	{ "cent",	162 }, /* cent sign  */
+	{ "copy",	169 }, /* copyright sign  */
+	{ "curren",	164 }, /* general currency sign  */
+	{ "deg",	176 }, /* degree sign  */
+	{ "divide",	247 }, /* divide sign  */
+	{ "eacute",	233 }, /* small e, acute accent  */
+	{ "ecirc",	234 }, /* small e, circumflex accent  */
+	{ "egrave",	232 }, /* small e, grave accent  */
+	{ "eth",	240 }, /* small eth, Icelandic  */
+	{ "euml",	235 }, /* small e, dieresis or umlaut mark  */
+	{ "frac12",	189 }, /* fraction one-half  */
+	{ "frac14",	188 }, /* fraction one-quarter  */
+	{ "frac34",	190 }, /* fraction three-quarters  */
+	{ "gt",		 62 }, /* greater than  */
+	{ "iacute",	237 }, /* small i, acute accent  */
+	{ "icirc",	238 }, /* small i, circumflex accent  */
+	{ "iexcl",	161 }, /* inverted exclamation mark  */
+	{ "igrave",	236 }, /* small i, grave accent  */
+	{ "iquest",	191 }, /* inverted question mark  */
+	{ "iuml",	239 }, /* small i, dieresis or umlaut mark  */
+	{ "laquo",	171 }, /* angle quotation mark, left  */
+	{ "lt",		 60 }, /* less than  */
+	{ "macr",	175 }, /* macron  */
+	{ "micro",	181 }, /* micro sign  */
+	{ "middot",	183 }, /* middle dot  */
+	{ "nbsp",	160 }, /* no-break space  */
+	{ "not",	172 }, /* not sign  */
+	{ "ntilde",	241 }, /* small n, tilde  */
+	{ "oacute",	243 }, /* small o, acute accent  */
+	{ "ocirc",	244 }, /* small o, circumflex accent  */
+	{ "ograve",	242 }, /* small o, grave accent  */
+	{ "ordf",	170 }, /* ordinal indicator, feminine  */
+	{ "ordm",	186 }, /* ordinal indicator, masculine  */
+	{ "oslash",	248 }, /* small o, slash  */
+	{ "otilde",	245 }, /* small o, tilde  */
+	{ "ouml",	246 }, /* small o, dieresis or umlaut mark  */
+	{ "para",	182 }, /* pilcrow (paragraph sign)  */
+	{ "plusmn",	177 }, /* plus-or-minus sign  */
+	{ "pound",	163 }, /* pound sterling sign  */
+	{ "quot",	 34 }, /* double quote  */
+	{ "raquo",	187 }, /* angle quotation mark, right  */
+	{ "reg",	174 }, /* registered sign  */
+	{ "sect",	167 }, /* section sign  */
+	{ "shy",	173 }, /* soft hyphen  */
+	{ "sup1",	185 }, /* superscript one  */
+	{ "sup2",	178 }, /* superscript two  */
+	{ "sup3",	179 }, /* superscript three  */
+	{ "szlig",	223 }, /* small sharp s, German (sz ligature)  */
+	{ "thorn",	254 }, /* small thorn, Icelandic  */
+	{ "times",	215 }, /* multiply sign  */
+	{ "uacute",	250 }, /* small u, acute accent  */
+	{ "ucirc",	251 }, /* small u, circumflex accent  */
+	{ "ugrave",	249 }, /* small u, grave accent  */
+	{ "uml",	168 }, /* umlaut (dieresis)  */
+	{ "uuml",	252 }, /* small u, dieresis or umlaut mark  */
+	{ "yacute",	253 }, /* small y, acute accent  */
+	{ "yen",	165 }, /* yen sign  */
+	{ "yuml",	255 }, /* small y, dieresis or umlaut mark  */
+};
+
+/*
+ * unvis - decode characters previously encoded by vis
+ */
+int
+unvis(char *cp, int c, int *astate, int flag)
+{
+	unsigned char uc = (unsigned char)c;
+	unsigned char st, ia, is, lc;
+
+/*
+ * Bottom 8 bits of astate hold the state machine state.
+ * Top 8 bits hold the current character in the http 1866 nv string decoding
+ */
+#define GS(a)		((a) & 0xff)
+#define SS(a, b)	(((uint32_t)(a) << 24) | (b))
+#define GI(a)		((uint32_t)(a) >> 24)
+
+	_DIAGASSERT(cp != NULL);
+	_DIAGASSERT(astate != NULL);
+	st = GS(*astate);
+
+	if (flag & UNVIS_END) {
+		switch (st) {
+		case S_OCTAL2:
+		case S_OCTAL3:
+		case S_HEX2:
+			*astate = SS(0, S_GROUND);
+			return UNVIS_VALID;
+		case S_GROUND:
+			return UNVIS_NOCHAR;
+		default:
+			return UNVIS_SYNBAD;
+		}
+	}
+
+	switch (st) {
+
+	case S_GROUND:
+		*cp = 0;
+		if ((flag & VIS_NOESCAPE) == 0 && c == '\\') {
+			*astate = SS(0, S_START);
+			return UNVIS_NOCHAR;
+		}
+		if ((flag & VIS_HTTP1808) && c == '%') {
+			*astate = SS(0, S_HEX1);
+			return UNVIS_NOCHAR;
+		}
+		if ((flag & VIS_HTTP1866) && c == '&') {
+			*astate = SS(0, S_AMP);
+			return UNVIS_NOCHAR;
+		}
+		if ((flag & VIS_MIMESTYLE) && c == '=') {
+			*astate = SS(0, S_MIME1);
+			return UNVIS_NOCHAR;
+		}
+		*cp = c;
+		return UNVIS_VALID;
+
+	case S_START:
+		switch(c) {
+		case '\\':
+			*cp = c;
+			*astate = SS(0, 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 = SS(0, S_OCTAL2);
+			return UNVIS_NOCHAR;
+		case 'M':
+			*cp = (char)0200;
+			*astate = SS(0, S_META);
+			return UNVIS_NOCHAR;
+		case '^':
+			*astate = SS(0, S_CTRL);
+			return UNVIS_NOCHAR;
+		case 'n':
+			*cp = '\n';
+			*astate = SS(0, S_GROUND);
+			return UNVIS_VALID;
+		case 'r':
+			*cp = '\r';
+			*astate = SS(0, S_GROUND);
+			return UNVIS_VALID;
+		case 'b':
+			*cp = '\b';
+			*astate = SS(0, S_GROUND);
+			return UNVIS_VALID;
+		case 'a':
+			*cp = '\007';
+			*astate = SS(0, S_GROUND);
+			return UNVIS_VALID;
+		case 'v':
+			*cp = '\v';
+			*astate = SS(0, S_GROUND);
+			return UNVIS_VALID;
+		case 't':
+			*cp = '\t';
+			*astate = SS(0, S_GROUND);
+			return UNVIS_VALID;
+		case 'f':
+			*cp = '\f';
+			*astate = SS(0, S_GROUND);
+			return UNVIS_VALID;
+		case 's':
+			*cp = ' ';
+			*astate = SS(0, S_GROUND);
+			return UNVIS_VALID;
+		case 'E':
+			*cp = '\033';
+			*astate = SS(0, S_GROUND);
+			return UNVIS_VALID;
+		case 'x':
+			*astate = SS(0, S_HEX);
+			return UNVIS_NOCHAR;
+		case '\n':
+			/*
+			 * hidden newline
+			 */
+			*astate = SS(0, S_GROUND);
+			return UNVIS_NOCHAR;
+		case '$':
+			/*
+			 * hidden marker
+			 */
+			*astate = SS(0, S_GROUND);
+			return UNVIS_NOCHAR;
+		}
+		goto bad;
+
+	case S_META:
+		if (c == '-')
+			*astate = SS(0, S_META1);
+		else if (c == '^')
+			*astate = SS(0, S_CTRL);
+		else 
+			goto bad;
+		return UNVIS_NOCHAR;
+
+	case S_META1:
+		*astate = SS(0, S_GROUND);
+		*cp |= c;
+		return UNVIS_VALID;
+
+	case S_CTRL:
+		if (c == '?')
+			*cp |= 0177;
+		else
+			*cp |= c & 037;
+		*astate = SS(0, S_GROUND);
+		return UNVIS_VALID;
+
+	case S_OCTAL2:	/* second possible octal digit */
+		if (isoctal(uc)) {
+			/*
+			 * yes - and maybe a third
+			 */
+			*cp = (*cp << 3) + (c - '0');
+			*astate = SS(0, S_OCTAL3);
+			return UNVIS_NOCHAR;
+		}
+		/*
+		 * no - done with current sequence, push back passed char
+		 */
+		*astate = SS(0, S_GROUND);
+		return UNVIS_VALIDPUSH;
+
+	case S_OCTAL3:	/* third possible octal digit */
+		*astate = SS(0, S_GROUND);
+		if (isoctal(uc)) {
+			*cp = (*cp << 3) + (c - '0');
+			return UNVIS_VALID;
+		}
+		/*
+		 * we were done, push back passed char
+		 */
+		return UNVIS_VALIDPUSH;
+
+	case S_HEX:
+		if (!isxdigit(uc))
+			goto bad;
+		/*FALLTHROUGH*/
+	case S_HEX1:
+		if (isxdigit(uc)) {
+			*cp = xtod(uc);
+			*astate = SS(0, S_HEX2);
+			return UNVIS_NOCHAR;
+		}
+		/*
+		 * no - done with current sequence, push back passed char
+		 */
+		*astate = SS(0, S_GROUND);
+		return UNVIS_VALIDPUSH;
+
+	case S_HEX2:
+		*astate = S_GROUND;
+		if (isxdigit(uc)) {
+			*cp = xtod(uc) | (*cp << 4);
+			return UNVIS_VALID;
+		}
+		return UNVIS_VALIDPUSH;
+
+	case S_MIME1:
+		if (uc == '\n' || uc == '\r') {
+			*astate = SS(0, S_EATCRNL);
+			return UNVIS_NOCHAR;
+		}
+		if (isxdigit(uc) && (isdigit(uc) || isupper(uc))) {
+			*cp = XTOD(uc);
+			*astate = SS(0, S_MIME2);
+			return UNVIS_NOCHAR;
+		}
+		goto bad;
+
+	case S_MIME2:
+		if (isxdigit(uc) && (isdigit(uc) || isupper(uc))) {
+			*astate = SS(0, S_GROUND);
+			*cp = XTOD(uc) | (*cp << 4);
+			return UNVIS_VALID;
+		}
+		goto bad;
+
+	case S_EATCRNL:
+		switch (uc) {
+		case '\r':
+		case '\n':
+			return UNVIS_NOCHAR;
+		case '=':
+			*astate = SS(0, S_MIME1);
+			return UNVIS_NOCHAR;
+		default:
+			*cp = uc;
+			*astate = SS(0, S_GROUND);
+			return UNVIS_VALID;
+		}
+
+	case S_AMP:
+		*cp = 0;
+		if (uc == '#') {
+			*astate = SS(0, S_NUMBER);
+			return UNVIS_NOCHAR;
+		}
+		*astate = SS(0, S_STRING);
+		/*FALLTHROUGH*/
+
+	case S_STRING:
+		ia = *cp;		/* index in the array */
+		is = GI(*astate);	/* index in the string */
+		lc = is == 0 ? 0 : nv[ia].name[is - 1];	/* last character */
+
+		if (uc == ';')
+			uc = '\0';
+
+		for (; ia < __arraycount(nv); ia++) {
+			if (is != 0 && nv[ia].name[is - 1] != lc)
+				goto bad;
+			if (nv[ia].name[is] == uc)
+				break;
+		}
+
+		if (ia == __arraycount(nv))
+			goto bad;
+
+		if (uc != 0) {
+			*cp = ia;
+			*astate = SS(is + 1, S_STRING);
+			return UNVIS_NOCHAR;
+		}
+
+		*cp = nv[ia].value;
+		*astate = SS(0, S_GROUND);
+		return UNVIS_VALID;
+
+	case S_NUMBER:
+		if (uc == ';')
+			return UNVIS_VALID;
+		if (!isdigit(uc))
+			goto bad;
+		*cp += (*cp * 10) + uc - '0';
+		return UNVIS_NOCHAR;
+
+	default:
+	bad:
+		/*
+		 * decoder in unknown state - (probably uninitialized)
+		 */
+		*astate = SS(0, S_GROUND);
+		return UNVIS_SYNBAD;
+	}
+}
+
+/*
+ * strnunvisx - decode src into dst
+ *
+ *	Number of chars decoded into dst is returned, -1 on error.
+ *	Dst is null terminated.
+ */
+
+int
+strnunvisx(char *dst, size_t dlen, const char *src, int flag)
+{
+	char c;
+	char t = '\0', *start = dst;
+	int state = 0;
+
+	_DIAGASSERT(src != NULL);
+	_DIAGASSERT(dst != NULL);
+#define CHECKSPACE() \
+	do { \
+		if (dlen-- == 0) { \
+			errno = ENOSPC; \
+			return -1; \
+		} \
+	} while (/*CONSTCOND*/0)
+
+	while ((c = *src++) != '\0') {
+ again:
+		switch (unvis(&t, c, &state, flag)) {
+		case UNVIS_VALID:
+			CHECKSPACE();
+			*dst++ = t;
+			break;
+		case UNVIS_VALIDPUSH:
+			CHECKSPACE();
+			*dst++ = t;
+			goto again;
+		case 0:
+		case UNVIS_NOCHAR:
+			break;
+		case UNVIS_SYNBAD:
+			errno = EINVAL;
+			return -1;
+		default:
+			_DIAGASSERT(/*CONSTCOND*/0);
+			errno = EINVAL;
+			return -1;
+		}
+	}
+	if (unvis(&t, c, &state, UNVIS_END) == UNVIS_VALID) {
+		CHECKSPACE();
+		*dst++ = t;
+	}
+	CHECKSPACE();
+	*dst = '\0';
+	return (int)(dst - start);
+}
+
+int
+strunvisx(char *dst, const char *src, int flag)
+{
+	return strnunvisx(dst, (size_t)~0, src, flag);
+}
+
+int
+strunvis(char *dst, const char *src)
+{
+	return strnunvisx(dst, (size_t)~0, src, 0);
+}
+
+int
+strnunvis(char *dst, size_t dlen, const char *src)
+{
+	return strnunvisx(dst, dlen, src, 0);
+}
+#endif
diff --git a/contrib/libc-vis/vis.3 b/contrib/libc-vis/vis.3
new file mode 100644
index 000000000000..6f5b15f8ce6d
--- /dev/null
+++ b/contrib/libc-vis/vis.3
@@ -0,0 +1,456 @@
+.\"	$NetBSD: vis.3,v 1.29 2012/12/14 22:55:59 christos Exp $
+.\"	$FreeBSD$
+.\"
+.\" Copyright (c) 1989, 1991, 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.
+.\"
+.\"     @(#)vis.3	8.1 (Berkeley) 6/9/93
+.\"
+.Dd December 14, 2012
+.Dt VIS 3
+.Os
+.Sh NAME
+.Nm vis ,
+.Nm nvis ,
+.Nm strvis ,
+.Nm strnvis ,
+.Nm strvisx ,
+.Nm strnvisx ,
+.Nm svis ,
+.Nm snvis ,
+.Nm strsvis ,
+.Nm strsnvis ,
+.Nm strsvisx
+.Nm strsnvisx
+.Nd visually encode characters
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.In vis.h
+.Ft char *
+.Fn vis "char *dst" "int c" "int flag" "int nextc"
+.Ft char *
+.Fn nvis "char *dst" "size_t dlen" "int c" "int flag" "int nextc"
+.Ft int
+.Fn strvis "char *dst" "const char *src" "int flag"
+.Ft int
+.Fn strnvis "char *dst" "size_t dlen" "const char *src" "int flag"
+.Ft int
+.Fn strvisx "char *dst" "const char *src" "size_t len" "int flag"
+.Ft int
+.Fn strnvisx "char *dst" "size_t dlen" "const char *src" "size_t len" "int flag"
+.Ft char *
+.Fn svis "char *dst" "int c" "int flag" "int nextc" "const char *extra"
+.Ft char *
+.Fn snvis "char *dst" "size_t dlen" "int c" "int flag" "int nextc" "const char *extra"
+.Ft int
+.Fn strsvis "char *dst" "const char *src" "int flag" "const char *extra"
+.Ft int
+.Fn strsnvis "char *dst" "size_t dlen" "const char *src" "int flag" "const char *extra"
+.Ft int
+.Fn strsvisx "char *dst" "const char *src" "size_t len" "int flag" "const char *extra"
+.Ft int
+.Fn strsnvisx "char *dst" "size_t dlen" "const char *src" "size_t len" "int flag" "const char *extra"
+.Sh DESCRIPTION
+The
+.Fn vis
+function
+copies into
+.Fa dst
+a string which represents the character
+.Fa c .
+If
+.Fa c
+needs no encoding, it is copied in unaltered.
+The string is null terminated, and a pointer to the end of the string is
+returned.
+The maximum length of any encoding is four
+characters (not including the trailing
+.Dv NUL ) ;
+thus, when
+encoding a set of characters into a buffer, the size of the buffer should
+be four times the number of characters encoded, plus one for the trailing
+.Dv NUL .
+The flag parameter is used for altering the default range of
+characters considered for encoding and for altering the visual
+representation.
+The additional character,
+.Fa nextc ,
+is only used when selecting the
+.Dv VIS_CSTYLE
+encoding format (explained below).
+.Pp
+The
+.Fn strvis ,
+.Fn strnvis ,
+.Fn strvisx ,
+and
+.Fn strnvisx
+functions copy into
+.Fa dst
+a visual representation of
+the string
+.Fa src .
+The
+.Fn strvis
+and
+.Fn strnvis
+functions encode characters from
+.Fa src
+up to the
+first
+.Dv NUL .
+The
+.Fn strvisx
+and
+.Fn strnvisx
+functions encode exactly
+.Fa len
+characters from
+.Fa src
+(this
+is useful for encoding a block of data that may contain
+.Dv NUL Ns 's ) .
+Both forms
+.Dv NUL
+terminate
+.Fa dst .
+The size of
+.Fa dst
+must be four times the number
+of characters encoded from
+.Fa src
+(plus one for the
+.Dv NUL ) .
+Both
+forms return the number of characters in dst (not including
+the trailing
+.Dv NUL ) .
+The
+.Dq n
+versions of the functions also take an additional argument
+.Fa dlen
+that indicates the length of the
+.Fa dst
+buffer.
+If
+.Fa dlen
+is not large enough to fix the converted string then the
+.Fn strnvis
+and
+.Fn strnvisx
+functions return \-1 and set
+.Va errno
+to
+.Dv ENOSPC .
+.Pp
+The functions
+.Fn svis ,
+.Fn snvis ,
+.Fn strsvis ,
+.Fn strsnvis ,
+.Fn strsvisx ,
+and
+.Fn strsnvisx
+correspond to
+.Fn vis ,
+.Fn nvis ,
+.Fn strvis ,
+.Fn strnvis ,
+.Fn strvisx ,
+and
+.Fn strnvisx
+but have an additional argument
+.Fa extra ,
+pointing to a
+.Dv NUL
+terminated list of characters.
+These characters will be copied encoded or backslash-escaped into
+.Fa dst .
+These functions are useful e.g. to remove the special meaning
+of certain characters to shells.
+.Pp
+The encoding is a unique, invertible representation composed entirely of
+graphic characters; it can be decoded back into the original form using
+the
+.Xr unvis 3 ,
+.Xr strunvis 3
+or
+.Xr strnunvis 3
+functions.
+.Pp
+There are two parameters that can be controlled: the range of
+characters that are encoded (applies only to
+.Fn vis ,
+.Fn nvis ,
+.Fn strvis ,
+.Fn strnvis ,
+.Fn strvisx ,
+and
+.Fn strnvisx ) ,
+and the type of representation used.
+By default, all non-graphic characters,
+except space, tab, and newline are encoded.
+(See
+.Xr isgraph 3 . )
+The following flags
+alter this:
+.Bl -tag -width VIS_WHITEX
+.It Dv VIS_GLOB
+Also encode magic characters
+.Ql ( * ,
+.Ql \&? ,
+.Ql \&[
+and
+.Ql # )
+recognized by
+.Xr glob 3 .
+.It Dv VIS_SP
+Also encode space.
+.It Dv VIS_TAB
+Also encode tab.
+.It Dv VIS_NL
+Also encode newline.
+.It Dv VIS_WHITE
+Synonym for
+.Dv VIS_SP
+\&|
+.Dv VIS_TAB
+\&|
+.Dv VIS_NL .
+.It Dv VIS_SAFE
+Only encode "unsafe" characters.
+Unsafe means control characters which may cause common terminals to perform
+unexpected functions.
+Currently this form allows space, tab, newline, backspace, bell, and
+return - in addition to all graphic characters - unencoded.
+.El
+.Pp
+(The above flags have no effect for
+.Fn svis ,
+.Fn snvis ,
+.Fn strsvis ,
+.Fn strsnvis ,
+.Fn strsvisx ,
+and
+.Fn strsnvisx .
+When using these functions, place all graphic characters to be
+encoded in an array pointed to by
+.Fa extra .
+In general, the backslash character should be included in this array, see the
+warning on the use of the
+.Dv VIS_NOSLASH
+flag below).
+.Pp
+There are four forms of encoding.
+All forms use the backslash character
+.Ql \e
+to introduce a special
+sequence; two backslashes are used to represent a real backslash,
+except
+.Dv VIS_HTTPSTYLE
+that uses
+.Ql % ,
+or
+.Dv VIS_MIMESTYLE
+that uses
+.Ql = .
+These are the visual formats:
+.Bl -tag -width VIS_CSTYLE
+.It (default)
+Use an
+.Ql M
+to represent meta characters (characters with the 8th
+bit set), and use caret
+.Ql ^
+to represent control characters see
+.Pf ( Xr iscntrl 3 ) .
+The following formats are used:
+.Bl -tag -width xxxxx
+.It Dv \e^C
+Represents the control character
+.Ql C .
+Spans characters
+.Ql \e000
+through
+.Ql \e037 ,
+and
+.Ql \e177
+(as
+.Ql \e^? ) .
+.It Dv \eM-C
+Represents character
+.Ql C
+with the 8th bit set.
+Spans characters
+.Ql \e241
+through
+.Ql \e376 .
+.It Dv \eM^C
+Represents control character
+.Ql C
+with the 8th bit set.
+Spans characters
+.Ql \e200
+through
+.Ql \e237 ,
+and
+.Ql \e377
+(as
+.Ql \eM^? ) .
+.It Dv \e040
+Represents
+.Tn ASCII
+space.
+.It Dv \e240
+Represents Meta-space.
+.El
+.Pp
+.It Dv VIS_CSTYLE
+Use C-style backslash sequences to represent standard non-printable
+characters.
+The following sequences are used to represent the indicated characters:
+.Bd -unfilled -offset indent
+.Li \ea Tn  - BEL No (007)
+.Li \eb Tn  - BS No (010)
+.Li \ef Tn  - NP No (014)
+.Li \en Tn  - NL No (012)
+.Li \er Tn  - CR No (015)
+.Li \es Tn  - SP No (040)
+.Li \et Tn  - HT No (011)
+.Li \ev Tn  - VT No (013)
+.Li \e0 Tn  - NUL No (000)
+.Ed
+.Pp
+When using this format, the nextc parameter is looked at to determine
+if a
+.Dv NUL
+character can be encoded as
+.Ql \e0
+instead of
+.Ql \e000 .
+If
+.Fa nextc
+is an octal digit, the latter representation is used to
+avoid ambiguity.
+.It Dv VIS_OCTAL
+Use a three digit octal sequence.
+The form is
+.Ql \eddd
+where
+.Em d
+represents an octal digit.
+.It Dv VIS_HTTPSTYLE
+Use URI encoding as described in RFC 1738.
+The form is
+.Ql %xx
+where
+.Em x
+represents a lower case hexadecimal digit.
+.It Dv VIS_MIMESTYLE
+Use MIME Quoted-Printable encoding as described in RFC 2045, only don't
+break lines and don't handle CRLF.
+The form is:
+.Ql %XX
+where
+.Em X
+represents an upper case hexadecimal digit.
+.El
+.Pp
+There is one additional flag,
+.Dv VIS_NOSLASH ,
+which inhibits the
+doubling of backslashes and the backslash before the default
+format (that is, control characters are represented by
+.Ql ^C
+and
+meta characters as
+.Ql M-C ) .
+With this flag set, the encoding is
+ambiguous and non-invertible.
+.Sh ERRORS
+The functions
+.Fn nvis
+and
+.Fn snvis
+will return
+.Dv NULL
+and the functions
+.Fn strnvis ,
+.Fn strnvisx ,
+.Fn strsnvis ,
+and
+.Fn strsnvisx ,
+will return \-1 when the
+.Fa dlen
+destination buffer length size is not enough to perform the conversion while
+setting
+.Va errno
+to:
+.Bl -tag -width Er
+.It Bq Er ENOSPC
+The destination buffer size is not large enough to perform the conversion.
+.El
+.Sh SEE ALSO
+.Xr unvis 1 ,
+.Xr vis 1 ,
+.Xr glob 3 ,
+.Xr unvis 3
+.Rs
+.%A T. Berners-Lee
+.%T Uniform Resource Locators (URL)
+.%O RFC1738
+.Re
+.Sh HISTORY
+The
+.Fn vis ,
+.Fn strvis ,
+and
+.Fa strvisx
+functions first appeared in
+.Bx 4.4 .
+The
+.Fn svis ,
+.Fn strsvis ,
+and
+.Fn strsvisx
+functions appeared in
+.Nx 1.5
+and
+.Fx 10.0 .
+The buffer size limited versions of the functions
+.Po Fn nvis ,
+.Fn strnvis ,
+.Fn strnvisx ,
+.Fn snvis ,
+.Fn strsnvis ,
+and
+.Fn strsnvisx Pc
+appeared in
+.Nx 6.0
+and
+.Fx 10.0 .
diff --git a/contrib/libc-vis/vis.c b/contrib/libc-vis/vis.c
new file mode 100644
index 000000000000..040c28c25e28
--- /dev/null
+++ b/contrib/libc-vis/vis.c
@@ -0,0 +1,583 @@
+/*	$NetBSD: vis.c,v 1.45 2012/12/14 21:38:18 christos 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.
+ */
+
+/*-
+ * Copyright (c) 1999, 2005 The NetBSD Foundation, Inc.
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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/cdefs.h>
+#if defined(LIBC_SCCS) && !defined(lint)
+__RCSID("$NetBSD: vis.c,v 1.45 2012/12/14 21:38:18 christos Exp $");
+#endif /* LIBC_SCCS and not lint */
+__FBSDID("$FreeBSD$");
+
+#include "namespace.h"
+#include <sys/types.h>
+
+#include <assert.h>
+#include <vis.h>
+#include <errno.h>
+#include <stdlib.h>
+
+#define	_DIAGASSERT(x)	assert(x)
+
+#ifdef __weak_alias
+__weak_alias(strvisx,_strvisx)
+#endif
+
+#if !HAVE_VIS || !HAVE_SVIS
+#include <ctype.h>
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+
+static char *do_svis(char *, size_t *, int, int, int, const char *);
+
+#undef BELL
+#define BELL '\a'
+
+#define isoctal(c)	(((u_char)(c)) >= '0' && ((u_char)(c)) <= '7')
+#define iswhite(c)	(c == ' ' || c == '\t' || c == '\n')
+#define issafe(c)	(c == '\b' || c == BELL || c == '\r')
+#define xtoa(c)		"0123456789abcdef"[c]
+#define XTOA(c)		"0123456789ABCDEF"[c]
+
+#define MAXEXTRAS	9
+
+#define MAKEEXTRALIST(flag, extra, orig_str)				      \
+do {									      \
+	const char *orig = orig_str;					      \
+	const char *o = orig;						      \
+	char *e;							      \
+	while (*o++)							      \
+		continue;						      \
+	extra = malloc((size_t)((o - orig) + MAXEXTRAS));		      \
+	if (!extra) break;						      \
+	for (o = orig, e = extra; (*e++ = *o++) != '\0';)		      \
+		continue;						      \
+	e--;								      \
+	if (flag & VIS_GLOB) {						      \
+		*e++ = '*';						      \
+		*e++ = '?';						      \
+		*e++ = '[';						      \
+		*e++ = '#';						      \
+	}								      \
+	if (flag & VIS_SP) *e++ = ' ';					      \
+	if (flag & VIS_TAB) *e++ = '\t';				      \
+	if (flag & VIS_NL) *e++ = '\n';					      \
+	if ((flag & VIS_NOSLASH) == 0) *e++ = '\\';			      \
+	*e = '\0';							      \
+} while (/*CONSTCOND*/0)
+
+/*
+ * This is do_hvis, for HTTP style (RFC 1808)
+ */
+static char *
+do_hvis(char *dst, size_t *dlen, int c, int flag, int nextc, const char *extra)
+{
+
+	if ((isascii(c) && isalnum(c))
+	    /* safe */
+	    || c == '$' || c == '-' || c == '_' || c == '.' || c == '+'
+	    /* extra */
+	    || c == '!' || c == '*' || c == '\'' || c == '(' || c == ')'
+	    || c == ',') {
+		dst = do_svis(dst, dlen, c, flag, nextc, extra);
+	} else {
+		if (dlen) {
+			if (*dlen < 3)
+				return NULL;
+			*dlen -= 3;
+		}
+		*dst++ = '%';
+		*dst++ = xtoa(((unsigned int)c >> 4) & 0xf);
+		*dst++ = xtoa((unsigned int)c & 0xf);
+	}
+
+	return dst;
+}
+
+/*
+ * This is do_mvis, for Quoted-Printable MIME (RFC 2045)
+ * NB: No handling of long lines or CRLF.
+ */
+static char *
+do_mvis(char *dst, size_t *dlen, int c, int flag, int nextc, const char *extra)
+{
+	if ((c != '\n') &&
+	    /* Space at the end of the line */
+	    ((isspace(c) && (nextc == '\r' || nextc == '\n')) ||
+	    /* Out of range */
+	    (!isspace(c) && (c < 33 || (c > 60 && c < 62) || c > 126)) ||
+	    /* Specific char to be escaped */ 
+	    strchr("#$@[\\]^`{|}~", c) != NULL)) {
+		if (dlen) {
+			if (*dlen < 3)
+				return NULL;
+			*dlen -= 3;
+		}
+		*dst++ = '=';
+		*dst++ = XTOA(((unsigned int)c >> 4) & 0xf);
+		*dst++ = XTOA((unsigned int)c & 0xf);
+	} else {
+		dst = do_svis(dst, dlen, c, flag, nextc, extra);
+	}
+	return dst;
+}
+
+/*
+ * This is do_vis, the central code of vis.
+ * dst:	      Pointer to the destination buffer
+ * c:	      Character to encode
+ * flag:      Flag word
+ * nextc:     The character following 'c'
+ * extra:     Pointer to the list of extra characters to be
+ *	      backslash-protected.
+ */
+static char *
+do_svis(char *dst, size_t *dlen, int c, int flag, int nextc, const char *extra)
+{
+	int isextra;
+	size_t odlen = dlen ? *dlen : 0;
+
+	isextra = strchr(extra, c) != NULL;
+#define HAVE(x) \
+	do { \
+		if (dlen) { \
+			if (*dlen < (x)) \
+				goto out; \
+			*dlen -= (x); \
+		} \
+	} while (/*CONSTCOND*/0)
+	if (!isextra && isascii(c) && (isgraph(c) || iswhite(c) ||
+	    ((flag & VIS_SAFE) && issafe(c)))) {
+		HAVE(1);
+		*dst++ = c;
+		return dst;
+	}
+	if (flag & VIS_CSTYLE) {
+		HAVE(2);
+		switch (c) {
+		case '\n':
+			*dst++ = '\\'; *dst++ = 'n';
+			return dst;
+		case '\r':
+			*dst++ = '\\'; *dst++ = 'r';
+			return dst;
+		case '\b':
+			*dst++ = '\\'; *dst++ = 'b';
+			return dst;
+		case BELL:
+			*dst++ = '\\'; *dst++ = 'a';
+			return dst;
+		case '\v':
+			*dst++ = '\\'; *dst++ = 'v';
+			return dst;
+		case '\t':
+			*dst++ = '\\'; *dst++ = 't';
+			return dst;
+		case '\f':
+			*dst++ = '\\'; *dst++ = 'f';
+			return dst;
+		case ' ':
+			*dst++ = '\\'; *dst++ = 's';
+			return dst;
+		case '\0':
+			*dst++ = '\\'; *dst++ = '0';
+			if (isoctal(nextc)) {
+				HAVE(2);
+				*dst++ = '0';
+				*dst++ = '0';
+			}
+			return dst;
+		default:
+			if (isgraph(c)) {
+				*dst++ = '\\'; *dst++ = c;
+				return dst;
+			}
+			if (dlen)
+				*dlen = odlen;
+		}
+	}
+	if (isextra || ((c & 0177) == ' ') || (flag & VIS_OCTAL)) {
+		HAVE(4);
+		*dst++ = '\\';
+		*dst++ = (u_char)(((u_int32_t)(u_char)c >> 6) & 03) + '0';
+		*dst++ = (u_char)(((u_int32_t)(u_char)c >> 3) & 07) + '0';
+		*dst++ =			     (c	      & 07) + '0';
+	} else {
+		if ((flag & VIS_NOSLASH) == 0) {
+			HAVE(1);
+			*dst++ = '\\';
+		}
+
+		if (c & 0200) {
+			HAVE(1);
+			c &= 0177; *dst++ = 'M';
+		}
+
+		if (iscntrl(c)) {
+			HAVE(2);
+			*dst++ = '^';
+			if (c == 0177)
+				*dst++ = '?';
+			else
+				*dst++ = c + '@';
+		} else {
+			HAVE(2);
+			*dst++ = '-'; *dst++ = c;
+		}
+	}
+	return dst;
+out:
+	*dlen = odlen;
+	return NULL;
+}
+
+typedef char *(*visfun_t)(char *, size_t *, int, int, int, const char *);
+
+/*
+ * Return the appropriate encoding function depending on the flags given.
+ */
+static visfun_t
+getvisfun(int flag)
+{
+	if (flag & VIS_HTTPSTYLE)
+		return do_hvis;
+	if (flag & VIS_MIMESTYLE)
+		return do_mvis;
+	return do_svis;
+}
+
+/*
+ * isnvis - visually encode characters, also encoding the characters
+ *	  pointed to by `extra'
+ */
+static char *
+isnvis(char *dst, size_t *dlen, int c, int flag, int nextc, const char *extra)
+{
+	char *nextra = NULL;
+	visfun_t f;
+
+	_DIAGASSERT(dst != NULL);
+	_DIAGASSERT(extra != NULL);
+	MAKEEXTRALIST(flag, nextra, extra);
+	if (!nextra) {
+		if (dlen && *dlen == 0) {
+			errno = ENOSPC;
+			return NULL;
+		}
+		*dst = '\0';		/* can't create nextra, return "" */
+		return dst;
+	}
+	f = getvisfun(flag);
+	dst = (*f)(dst, dlen, c, flag, nextc, nextra);
+	free(nextra);
+	if (dst == NULL || (dlen && *dlen == 0)) {
+		errno = ENOSPC;
+		return NULL;
+	}
+	*dst = '\0';
+	return dst;
+}
+
+char *
+svis(char *dst, int c, int flag, int nextc, const char *extra)
+{
+	return isnvis(dst, NULL, c, flag, nextc, extra);
+}
+
+char *
+snvis(char *dst, size_t dlen, int c, int flag, int nextc, const char *extra)
+{
+	return isnvis(dst, &dlen, c, flag, nextc, extra);
+}
+
+
+/*
+ * strsvis, strsvisx - visually encode characters from src into dst
+ *
+ *	Extra is a pointer to a \0-terminated list of characters to
+ *	be encoded, too. These functions are useful e. g. to
+ *	encode strings in such a way so that they are not interpreted
+ *	by a shell.
+ *
+ *	Dst must be 4 times the size of src to account for possible
+ *	expansion.  The length of dst, not including the trailing NULL,
+ *	is returned.
+ *
+ *	Strsvisx encodes exactly len bytes from src into dst.
+ *	This is useful for encoding a block of data.
+ */
+static int
+istrsnvis(char *dst, size_t *dlen, const char *csrc, int flag, const char *extra)
+{
+	int c;
+	char *start;
+	char *nextra = NULL;
+	const unsigned char *src = (const unsigned char *)csrc;
+	visfun_t f;
+
+	_DIAGASSERT(dst != NULL);
+	_DIAGASSERT(src != NULL);
+	_DIAGASSERT(extra != NULL);
+	MAKEEXTRALIST(flag, nextra, extra);
+	if (!nextra) {
+		*dst = '\0';		/* can't create nextra, return "" */
+		return 0;
+	}
+	f = getvisfun(flag);
+	for (start = dst; (c = *src++) != '\0'; /* empty */) {
+		dst = (*f)(dst, dlen, c, flag, *src, nextra);
+		if (dst == NULL) {
+			errno = ENOSPC;
+			return -1;
+		}
+	}
+	free(nextra);
+	if (dlen && *dlen == 0) {
+		errno = ENOSPC;
+		return -1;
+	}
+	*dst = '\0';
+	return (int)(dst - start);
+}
+
+int
+strsvis(char *dst, const char *csrc, int flag, const char *extra)
+{
+	return istrsnvis(dst, NULL, csrc, flag, extra);
+}
+
+int
+strsnvis(char *dst, size_t dlen, const char *csrc, int flag, const char *extra)
+{
+	return istrsnvis(dst, &dlen, csrc, flag, extra);
+}
+
+static int
+istrsnvisx(char *dst, size_t *dlen, const char *csrc, size_t len, int flag,
+    const char *extra)
+{
+	unsigned char c;
+	char *start;
+	char *nextra = NULL;
+	const unsigned char *src = (const unsigned char *)csrc;
+	visfun_t f;
+
+	_DIAGASSERT(dst != NULL);
+	_DIAGASSERT(src != NULL);
+	_DIAGASSERT(extra != NULL);
+	MAKEEXTRALIST(flag, nextra, extra);
+	if (! nextra) {
+		if (dlen && *dlen == 0) {
+			errno = ENOSPC;
+			return -1;
+		}
+		*dst = '\0';		/* can't create nextra, return "" */
+		return 0;
+	}
+
+	f = getvisfun(flag);
+	for (start = dst; len > 0; len--) {
+		c = *src++;
+		dst = (*f)(dst, dlen, c, flag, len > 1 ? *src : '\0', nextra);
+		if (dst == NULL) {
+			errno = ENOSPC;
+			return -1;
+		}
+	}
+	free(nextra);
+	if (dlen && *dlen == 0) {
+		errno = ENOSPC;
+		return -1;
+	}
+	*dst = '\0';
+	return (int)(dst - start);
+}
+
+int
+strsvisx(char *dst, const char *csrc, size_t len, int flag, const char *extra)
+{
+	return istrsnvisx(dst, NULL, csrc, len, flag, extra);
+}
+
+int
+strsnvisx(char *dst, size_t dlen, const char *csrc, size_t len, int flag,
+    const char *extra)
+{
+	return istrsnvisx(dst, &dlen, csrc, len, flag, extra);
+}
+#endif
+
+#if !HAVE_VIS
+/*
+ * vis - visually encode characters
+ */
+static char *
+invis(char *dst, size_t *dlen, int c, int flag, int nextc)
+{
+	char *extra = NULL;
+	unsigned char uc = (unsigned char)c;
+	visfun_t f;
+
+	_DIAGASSERT(dst != NULL);
+
+	MAKEEXTRALIST(flag, extra, "");
+	if (! extra) {
+		if (dlen && *dlen == 0) {
+			errno = ENOSPC;
+			return NULL;
+		}
+		*dst = '\0';		/* can't create extra, return "" */
+		return dst;
+	}
+	f = getvisfun(flag);
+	dst = (*f)(dst, dlen, uc, flag, nextc, extra);
+	free(extra);
+	if (dst == NULL || (dlen && *dlen == 0)) {
+		errno = ENOSPC;
+		return NULL;
+	}
+	*dst = '\0';
+	return dst;
+}
+
+char *
+vis(char *dst, int c, int flag, int nextc)
+{
+	return invis(dst, NULL, c, flag, nextc);
+}
+
+char *
+nvis(char *dst, size_t dlen, int c, int flag, int nextc)
+{
+	return invis(dst, &dlen, c, flag, nextc);
+}
+
+
+/*
+ * strvis, strvisx - visually encode characters from src into dst
+ *
+ *	Dst must be 4 times the size of src to account for possible
+ *	expansion.  The length of dst, not including the trailing NULL,
+ *	is returned.
+ *
+ *	Strvisx encodes exactly len bytes from src into dst.
+ *	This is useful for encoding a block of data.
+ */
+static int
+istrnvis(char *dst, size_t *dlen, const char *src, int flag)
+{
+	char *extra = NULL;
+	int rv;
+
+	MAKEEXTRALIST(flag, extra, "");
+	if (!extra) {
+		if (dlen && *dlen == 0) {
+			errno = ENOSPC;
+			return -1;
+		}
+		*dst = '\0';		/* can't create extra, return "" */
+		return 0;
+	}
+	rv = istrsnvis(dst, dlen, src, flag, extra);
+	free(extra);
+	return rv;
+}
+
+int
+strvis(char *dst, const char *src, int flag)
+{
+	return istrnvis(dst, NULL, src, flag);
+}
+
+int
+strnvis(char *dst, size_t dlen, const char *src, int flag)
+{
+	return istrnvis(dst, &dlen, src, flag);
+}
+
+static int
+istrnvisx(char *dst, size_t *dlen, const char *src, size_t len, int flag)
+{
+	char *extra = NULL;
+	int rv;
+
+	MAKEEXTRALIST(flag, extra, "");
+	if (!extra) {
+		if (dlen && *dlen == 0) {
+			errno = ENOSPC;
+			return -1;
+		}
+		*dst = '\0';		/* can't create extra, return "" */
+		return 0;
+	}
+	rv = istrsnvisx(dst, dlen, src, len, flag, extra);
+	free(extra);
+	return rv;
+}
+
+int
+strvisx(char *dst, const char *src, size_t len, int flag)
+{
+	return istrnvisx(dst, NULL, src, len, flag);
+}
+
+int
+strnvisx(char *dst, size_t dlen, const char *src, size_t len, int flag)
+{
+	return istrnvisx(dst, &dlen, src, len, flag);
+}
+
+#endif
diff --git a/contrib/libc-vis/vis.h b/contrib/libc-vis/vis.h
new file mode 100644
index 000000000000..cd7680e1dc74
--- /dev/null
+++ b/contrib/libc-vis/vis.h
@@ -0,0 +1,114 @@
+/*	$NetBSD: vis.h,v 1.20 2012/12/14 21:36:59 christos Exp $	*/
+/*	$FreeBSD$	*/
+
+/*-
+ * Copyright (c) 1990, 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.
+ *
+ *	@(#)vis.h	8.1 (Berkeley) 6/2/93
+ */
+
+#ifndef _VIS_H_
+#define	_VIS_H_
+
+#include <sys/types.h>
+
+/*
+ * to select alternate encoding format
+ */
+#define	VIS_OCTAL	0x0001	/* use octal \ddd format */
+#define	VIS_CSTYLE	0x0002	/* use \[nrft0..] where appropiate */
+
+/*
+ * to alter set of characters encoded (default is to encode all
+ * non-graphic except space, tab, and newline).
+ */
+#define	VIS_SP		0x0004	/* also encode space */
+#define	VIS_TAB		0x0008	/* also encode tab */
+#define	VIS_NL		0x0010	/* also encode newline */
+#define	VIS_WHITE	(VIS_SP | VIS_TAB | VIS_NL)
+#define	VIS_SAFE	0x0020	/* only encode "unsafe" characters */
+
+/*
+ * other
+ */
+#define	VIS_NOSLASH	0x0040	/* inhibit printing '\' */
+#define	VIS_HTTP1808	0x0080	/* http-style escape % hex hex */
+#define	VIS_HTTPSTYLE	0x0080	/* http-style escape % hex hex */
+#define	VIS_GLOB	0x0100	/* encode glob(3) magic characters */
+#define	VIS_MIMESTYLE	0x0200	/* mime-style escape = HEX HEX */
+#define	VIS_HTTP1866	0x0400	/* http-style &#num; or &string; */
+#define	VIS_NOESCAPE	0x0800	/* don't decode `\' */
+#define	_VIS_END	0x1000	/* for unvis */
+
+/*
+ * unvis return codes
+ */
+#define	UNVIS_VALID	 1	/* character valid */
+#define	UNVIS_VALIDPUSH	 2	/* character valid, push back passed char */
+#define	UNVIS_NOCHAR	 3	/* valid sequence, no character produced */
+#define	UNVIS_SYNBAD	-1	/* unrecognized escape sequence */
+#define	UNVIS_ERROR	-2	/* decoder in unknown state (unrecoverable) */
+
+/*
+ * unvis flags
+ */
+#define	UNVIS_END	_VIS_END	/* no more characters */
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+char	*vis(char *, int, int, int);
+char	*nvis(char *, size_t, int, int, int);
+
+char	*svis(char *, int, int, int, const char *);
+char	*snvis(char *, size_t, int, int, int, const char *);
+
+int	strvis(char *, const char *, int);
+int	strnvis(char *, size_t, const char *, int);
+
+int	strsvis(char *, const char *, int, const char *);
+int	strsnvis(char *, size_t, const char *, int, const char *);
+
+int	strvisx(char *, const char *, size_t, int);
+int	strnvisx(char *, size_t, const char *, size_t, int);
+
+int	strsvisx(char *, const char *, size_t, int, const char *);
+int	strsnvisx(char *, size_t, const char *, size_t, int, const char *);
+
+int	strunvis(char *, const char *);
+int	strnunvis(char *, size_t, const char *);
+
+int	strunvisx(char *, const char *, int);
+int	strnunvisx(char *, size_t, const char *, int);
+
+#ifndef __LIBC12_SOURCE__
+int	unvis(char *, int, int *, int);
+#endif
+__END_DECLS
+
+#endif /* !_VIS_H_ */