xref: /freebsd/contrib/libc-vis/vis.c (revision 1a2f06d0f2905c9a18340b377cbbe772f2ca6844)

/*	$NetBSD: vis.c,v 1.74 2017/11/27 16:37:21 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 1.74 2017/11/27 16:37:21 christos Exp $");
#endif /* LIBC_SCCS and not lint */
#ifdef __FBSDID
__FBSDID("$FreeBSD$");
#define	_DIAGASSERT(x)	assert(x)
#endif

#include "namespace.h"
#include <sys/types.h>
#include <sys/param.h>

#include <assert.h>
#include <vis.h>
#include <errno.h>
#include <stdlib.h>
#include <wchar.h>
#include <wctype.h>

#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>

/*
 * The reason for going through the trouble to deal with character encodings
 * in vis(3), is that we use this to safe encode output of commands. This
 * safe encoding varies depending on the character set. For example if we
 * display ps output in French, we don't want to display French characters
 * as M-foo.
 */

static wchar_t *do_svis(wchar_t *, wint_t, int, wint_t, const wchar_t *);

#undef BELL
#define BELL L'\a'

#if defined(LC_C_LOCALE)
#define iscgraph(c)      isgraph_l(c, LC_C_LOCALE)
#else
/* Keep it simple for now, no locale stuff */
#define iscgraph(c)	isgraph(c)
#ifdef notyet
#include <locale.h>
static int
iscgraph(int c) {
	int rv;
	char *ol;

	ol = setlocale(LC_CTYPE, "C");
	rv = isgraph(c);
	if (ol)
		setlocale(LC_CTYPE, ol);
	return rv;
}
#endif
#endif

#define ISGRAPH(flags, c) \
    (((flags) & VIS_NOLOCALE) ? iscgraph(c) : iswgraph(c))

#define iswoctal(c)	(((u_char)(c)) >= L'0' && ((u_char)(c)) <= L'7')
#define iswwhite(c)	(c == L' ' || c == L'\t' || c == L'\n')
#define iswsafe(c)	(c == L'\b' || c == BELL || c == L'\r')
#define xtoa(c)		L"0123456789abcdef"[c]
#define XTOA(c)		L"0123456789ABCDEF"[c]

#define MAXEXTRAS	30

static const wchar_t char_shell[] = L"'`\";&<>()|{}]\\$!^~";
static const wchar_t char_glob[] = L"*?[#";

#if !HAVE_NBTOOL_CONFIG_H
#ifndef __NetBSD__
/*
 * On NetBSD MB_LEN_MAX is currently 32 which does not fit on any integer
 * integral type and it is probably wrong, since currently the maximum
 * number of bytes and character needs is 6. Until this is fixed, the
 * loops below are using sizeof(uint64_t) - 1 instead of MB_LEN_MAX, and
 * the assertion is commented out.
 */
#ifdef __FreeBSD__
/*
 * On FreeBSD including <sys/systm.h> for CTASSERT only works in kernel
 * mode.
 */
#ifndef CTASSERT
#define CTASSERT(x)             _CTASSERT(x, __LINE__)
#define _CTASSERT(x, y)         __CTASSERT(x, y)
#define __CTASSERT(x, y)        typedef char __assert ## y[(x) ? 1 : -1]
#endif
#endif /* __FreeBSD__ */
CTASSERT(MB_LEN_MAX <= sizeof(uint64_t));
#endif /* !__NetBSD__ */
#endif

/*
 * This is do_hvis, for HTTP style (RFC 1808)
 */
static wchar_t *
do_hvis(wchar_t *dst, wint_t c, int flags, wint_t nextc, const wchar_t *extra)
{
	if (iswalnum(c)
	    /* safe */
	    || c == L'$' || c == L'-' || c == L'_' || c == L'.' || c == L'+'
	    /* extra */
	    || c == L'!' || c == L'*' || c == L'\'' || c == L'(' || c == L')'
	    || c == L',')
		dst = do_svis(dst, c, flags, nextc, extra);
	else {
		*dst++ = L'%';
		*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 wchar_t *
do_mvis(wchar_t *dst, wint_t c, int flags, wint_t nextc, const wchar_t *extra)
{
	if ((c != L'\n') &&
	    /* Space at the end of the line */
	    ((iswspace(c) && (nextc == L'\r' || nextc == L'\n')) ||
	    /* Out of range */
	    (!iswspace(c) && (c < 33 || (c > 60 && c < 62) || c > 126)) ||
	    /* Specific char to be escaped */
	    wcschr(L"#$@[\\]^`{|}~", c) != NULL)) {
		*dst++ = L'=';
		*dst++ = XTOA(((unsigned int)c >> 4) & 0xf);
		*dst++ = XTOA((unsigned int)c & 0xf);
	} else
		dst = do_svis(dst, c, flags, nextc, extra);
	return dst;
}

/*
 * Output single byte of multibyte character.
 */
static wchar_t *
do_mbyte(wchar_t *dst, wint_t c, int flags, wint_t nextc, int iswextra)
{
	if (flags & VIS_CSTYLE) {
		switch (c) {
		case L'\n':
			*dst++ = L'\\'; *dst++ = L'n';
			return dst;
		case L'\r':
			*dst++ = L'\\'; *dst++ = L'r';
			return dst;
		case L'\b':
			*dst++ = L'\\'; *dst++ = L'b';
			return dst;
		case BELL:
			*dst++ = L'\\'; *dst++ = L'a';
			return dst;
		case L'\v':
			*dst++ = L'\\'; *dst++ = L'v';
			return dst;
		case L'\t':
			*dst++ = L'\\'; *dst++ = L't';
			return dst;
		case L'\f':
			*dst++ = L'\\'; *dst++ = L'f';
			return dst;
		case L' ':
			*dst++ = L'\\'; *dst++ = L's';
			return dst;
		case L'\0':
			*dst++ = L'\\'; *dst++ = L'0';
			if (iswoctal(nextc)) {
				*dst++ = L'0';
				*dst++ = L'0';
			}
			return dst;
		/* We cannot encode these characters in VIS_CSTYLE
		 * because they special meaning */
		case L'n':
		case L'r':
		case L'b':
		case L'a':
		case L'v':
		case L't':
		case L'f':
		case L's':
		case L'0':
		case L'M':
		case L'^':
		case L'$': /* vis(1) -l */
			break;
		default:
			if (ISGRAPH(flags, c) && !iswoctal(c)) {
				*dst++ = L'\\';
				*dst++ = c;
				return dst;
			}
		}
	}
	if (iswextra || ((c & 0177) == L' ') || (flags & VIS_OCTAL)) {
		*dst++ = L'\\';
		*dst++ = (u_char)(((u_int32_t)(u_char)c >> 6) & 03) + L'0';
		*dst++ = (u_char)(((u_int32_t)(u_char)c >> 3) & 07) + L'0';
		*dst++ =			     (c	      & 07) + L'0';
	} else {
		if ((flags & VIS_NOSLASH) == 0)
			*dst++ = L'\\';

		if (c & 0200) {
			c &= 0177;
			*dst++ = L'M';
		}

		if (iswcntrl(c)) {
			*dst++ = L'^';
			if (c == 0177)
				*dst++ = L'?';
			else
				*dst++ = c + L'@';
		} else {
			*dst++ = L'-';
			*dst++ = c;
		}
	}

	return dst;
}

/*
 * This is do_vis, the central code of vis.
 * dst:	      Pointer to the destination buffer
 * c:	      Character to encode
 * flags:     Flags word
 * nextc:     The character following 'c'
 * extra:     Pointer to the list of extra characters to be
 *	      backslash-protected.
 */
static wchar_t *
do_svis(wchar_t *dst, wint_t c, int flags, wint_t nextc, const wchar_t *extra)
{
	int iswextra, i, shft;
	uint64_t bmsk, wmsk;

	iswextra = wcschr(extra, c) != NULL;
	if (!iswextra && (ISGRAPH(flags, c) || iswwhite(c) ||
	    ((flags & VIS_SAFE) && iswsafe(c)))) {
		*dst++ = c;
		return dst;
	}

	/* See comment in istrsenvisx() output loop, below. */
	wmsk = 0;
	for (i = sizeof(wmsk) - 1; i >= 0; i--) {
		shft = i * NBBY;
		bmsk = (uint64_t)0xffLL << shft;
		wmsk |= bmsk;
		if ((c & wmsk) || i == 0)
			dst = do_mbyte(dst, (wint_t)(
			    (uint64_t)(c & bmsk) >> shft),
			    flags, nextc, iswextra);
	}

	return dst;
}

typedef wchar_t *(*visfun_t)(wchar_t *, wint_t, int, wint_t, const wchar_t *);

/*
 * Return the appropriate encoding function depending on the flags given.
 */
static visfun_t
getvisfun(int flags)
{
	if (flags & VIS_HTTPSTYLE)
		return do_hvis;
	if (flags & VIS_MIMESTYLE)
		return do_mvis;
	return do_svis;
}

/*
 * Expand list of extra characters to not visually encode.
 */
static wchar_t *
makeextralist(int flags, const char *src)
{
	wchar_t *dst, *d;
	size_t len;
	const wchar_t *s;
	mbstate_t mbstate;

	bzero(&mbstate, sizeof(mbstate));
	len = strlen(src);
	if ((dst = calloc(len + MAXEXTRAS, sizeof(*dst))) == NULL)
		return NULL;

	if ((flags & VIS_NOLOCALE) || mbsrtowcs(dst, &src, len, &mbstate) == (size_t)-1) {
		size_t i;
		for (i = 0; i < len; i++)
			dst[i] = (wchar_t)(u_char)src[i];
		d = dst + len;
	} else
		d = dst + wcslen(dst);

	if (flags & VIS_GLOB)
		for (s = char_glob; *s; *d++ = *s++)
			continue;

	if (flags & VIS_SHELL)
		for (s = char_shell; *s; *d++ = *s++)
			continue;

	if (flags & VIS_SP) *d++ = L' ';
	if (flags & VIS_TAB) *d++ = L'\t';
	if (flags & VIS_NL) *d++ = L'\n';
	if (flags & VIS_DQ) *d++ = L'"';
	if ((flags & VIS_NOSLASH) == 0) *d++ = L'\\';
	*d = L'\0';

	return dst;
}

/*
 * istrsenvisx()
 * 	The main internal function.
 *	All user-visible functions call this one.
 */
static int
istrsenvisx(char **mbdstp, size_t *dlen, const char *mbsrc, size_t mblength,
    int flags, const char *mbextra, int *cerr_ptr)
{
	wchar_t *dst, *src, *pdst, *psrc, *start, *extra;
	size_t len, olen;
	uint64_t bmsk, wmsk;
	wint_t c;
	visfun_t f;
	int clen = 0, cerr, error = -1, i, shft;
	char *mbdst, *mdst;
	ssize_t mbslength, maxolen;
	mbstate_t mbstate;

	_DIAGASSERT(mbdstp != NULL);
	_DIAGASSERT(mbsrc != NULL || mblength == 0);
	_DIAGASSERT(mbextra != NULL);

	mbslength = (ssize_t)mblength;
	/*
	 * When inputing a single character, must also read in the
	 * next character for nextc, the look-ahead character.
	 */
	if (mbslength == 1)
		mbslength++;

	/*
	 * Input (mbsrc) is a char string considered to be multibyte
	 * characters.  The input loop will read this string pulling
	 * one character, possibly multiple bytes, from mbsrc and
	 * converting each to wchar_t in src.
	 *
	 * The vis conversion will be done using the wide char
	 * wchar_t string.
	 *
	 * This will then be converted back to a multibyte string to
	 * return to the caller.
	 */

	/* Allocate space for the wide char strings */
	psrc = pdst = extra = NULL;
	mdst = NULL;
	if ((psrc = calloc(mbslength + 1, sizeof(*psrc))) == NULL)
		return -1;
	if ((pdst = calloc((16 * mbslength) + 1, sizeof(*pdst))) == NULL)
		goto out;
	if (*mbdstp == NULL) {
		if ((mdst = calloc((16 * mbslength) + 1, sizeof(*mdst))) == NULL)
			goto out;
		*mbdstp = mdst;
	}

	mbdst = *mbdstp;
	dst = pdst;
	src = psrc;

	if (flags & VIS_NOLOCALE) {
		/* Do one byte at a time conversion */
		cerr = 1;
	} else {
		/* Use caller's multibyte conversion error flag. */
		cerr = cerr_ptr ? *cerr_ptr : 0;
	}

	/*
	 * Input loop.
	 * Handle up to mblength characters (not bytes).  We do not
	 * stop at NULs because we may be processing a block of data
	 * that includes NULs.
	 */
	bzero(&mbstate, sizeof(mbstate));
	while (mbslength > 0) {
		/* Convert one multibyte character to wchar_t. */
		if (!cerr)
			clen = mbrtowc(src, mbsrc, MIN(mbslength, MB_LEN_MAX),
			    &mbstate);
		if (cerr || clen < 0) {
			/* Conversion error, process as a byte instead. */
			*src = (wint_t)(u_char)*mbsrc;
			clen = 1;
			cerr = 1;
		}
		if (clen == 0) {
			/*
			 * NUL in input gives 0 return value. process
			 * as single NUL byte and keep going.
			 */
			clen = 1;
		}
		/* Advance buffer character pointer. */
		src++;
		/* Advance input pointer by number of bytes read. */
		mbsrc += clen;
		/* Decrement input byte count. */
		mbslength -= clen;
	}
	len = src - psrc;
	src = psrc;

	/*
	 * In the single character input case, we will have actually
	 * processed two characters, c and nextc.  Reset len back to
	 * just a single character.
	 */
	if (mblength < len)
		len = mblength;

	/* Convert extra argument to list of characters for this mode. */
	extra = makeextralist(flags, mbextra);
	if (!extra) {
		if (dlen && *dlen == 0) {
			errno = ENOSPC;
			goto out;
		}
		*mbdst = '\0';	/* can't create extra, return "" */
		error = 0;
		goto out;
	}

	/* Look up which processing function to call. */
	f = getvisfun(flags);

	/*
	 * Main processing loop.
	 * Call do_Xvis processing function one character at a time
	 * with next character available for look-ahead.
	 */
	for (start = dst; len > 0; len--) {
		c = *src++;
		dst = (*f)(dst, c, flags, len >= 1 ? *src : L'\0', extra);
		if (dst == NULL) {
			errno = ENOSPC;
			goto out;
		}
	}

	/* Terminate the string in the buffer. */
	*dst = L'\0';

	/*
	 * Output loop.
	 * Convert wchar_t string back to multibyte output string.
	 * If we have hit a multi-byte conversion error on input,
	 * output byte-by-byte here.  Else use wctomb().
	 */
	len = wcslen(start);
	maxolen = dlen ? *dlen : (wcslen(start) * MB_LEN_MAX + 1);
	olen = 0;
	bzero(&mbstate, sizeof(mbstate));
	for (dst = start; len > 0; len--) {
		if (!cerr)
			clen = wcrtomb(mbdst, *dst, &mbstate);
		if (cerr || clen < 0) {
			/*
			 * Conversion error, process as a byte(s) instead.
			 * Examine each byte and higher-order bytes for
			 * data.  E.g.,
			 *	0x000000000000a264 -> a2 64
			 *	0x000000001f00a264 -> 1f 00 a2 64
			 */
			clen = 0;
			wmsk = 0;
			for (i = sizeof(wmsk) - 1; i >= 0; i--) {
				shft = i * NBBY;
				bmsk = (uint64_t)0xffLL << shft;
				wmsk |= bmsk;
				if ((*dst & wmsk) || i == 0)
					mbdst[clen++] = (char)(
					    (uint64_t)(*dst & bmsk) >>
					    shft);
			}
			cerr = 1;
		}
		/* If this character would exceed our output limit, stop. */
		if (olen + clen > (size_t)maxolen)
			break;
		/* Advance output pointer by number of bytes written. */
		mbdst += clen;
		/* Advance buffer character pointer. */
		dst++;
		/* Incrment output character count. */
		olen += clen;
	}

	/* Terminate the output string. */
	*mbdst = '\0';

	if (flags & VIS_NOLOCALE) {
		/* Pass conversion error flag out. */
		if (cerr_ptr)
			*cerr_ptr = cerr;
	}

	free(extra);
	free(pdst);
	free(psrc);

	return (int)olen;
out:
	free(extra);
	free(pdst);
	free(psrc);
	free(mdst);
	return error;
}

static int
istrsenvisxl(char **mbdstp, size_t *dlen, const char *mbsrc,
    int flags, const char *mbextra, int *cerr_ptr)
{
	return istrsenvisx(mbdstp, dlen, mbsrc,
	    mbsrc != NULL ? strlen(mbsrc) : 0, flags, mbextra, cerr_ptr);
}

#endif

#if !HAVE_SVIS
/*
 *	The "svis" variants all take an "extra" arg that is a pointer
 *	to a NUL-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.
 */

char *
svis(char *mbdst, int c, int flags, int nextc, const char *mbextra)
{
	char cc[2];
	int ret;

	cc[0] = c;
	cc[1] = nextc;

	ret = istrsenvisx(&mbdst, NULL, cc, 1, flags, mbextra, NULL);
	if (ret < 0)
		return NULL;
	return mbdst + ret;
}

char *
snvis(char *mbdst, size_t dlen, int c, int flags, int nextc, const char *mbextra)
{
	char cc[2];
	int ret;

	cc[0] = c;
	cc[1] = nextc;

	ret = istrsenvisx(&mbdst, &dlen, cc, 1, flags, mbextra, NULL);
	if (ret < 0)
		return NULL;
	return mbdst + ret;
}

int
strsvis(char *mbdst, const char *mbsrc, int flags, const char *mbextra)
{
	return istrsenvisxl(&mbdst, NULL, mbsrc, flags, mbextra, NULL);
}

int
strsnvis(char *mbdst, size_t dlen, const char *mbsrc, int flags, const char *mbextra)
{
	return istrsenvisxl(&mbdst, &dlen, mbsrc, flags, mbextra, NULL);
}

int
strsvisx(char *mbdst, const char *mbsrc, size_t len, int flags, const char *mbextra)
{
	return istrsenvisx(&mbdst, NULL, mbsrc, len, flags, mbextra, NULL);
}

int
strsnvisx(char *mbdst, size_t dlen, const char *mbsrc, size_t len, int flags,
    const char *mbextra)
{
	return istrsenvisx(&mbdst, &dlen, mbsrc, len, flags, mbextra, NULL);
}

int
strsenvisx(char *mbdst, size_t dlen, const char *mbsrc, size_t len, int flags,
    const char *mbextra, int *cerr_ptr)
{
	return istrsenvisx(&mbdst, &dlen, mbsrc, len, flags, mbextra, cerr_ptr);
}
#endif

#if !HAVE_VIS
/*
 * vis - visually encode characters
 */
char *
vis(char *mbdst, int c, int flags, int nextc)
{
	char cc[2];
	int ret;

	cc[0] = c;
	cc[1] = nextc;

	ret = istrsenvisx(&mbdst, NULL, cc, 1, flags, "", NULL);
	if (ret < 0)
		return NULL;
	return mbdst + ret;
}

char *
nvis(char *mbdst, size_t dlen, int c, int flags, int nextc)
{
	char cc[2];
	int ret;

	cc[0] = c;
	cc[1] = nextc;

	ret = istrsenvisx(&mbdst, &dlen, cc, 1, flags, "", NULL);
	if (ret < 0)
		return NULL;
	return mbdst + ret;
}

/*
 * strvis - 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.
 */

int
strvis(char *mbdst, const char *mbsrc, int flags)
{
	return istrsenvisxl(&mbdst, NULL, mbsrc, flags, "", NULL);
}

int
strnvis(char *mbdst, size_t dlen, const char *mbsrc, int flags)
{
	return istrsenvisxl(&mbdst, &dlen, mbsrc, flags, "", NULL);
}

int
stravis(char **mbdstp, const char *mbsrc, int flags)
{
	*mbdstp = NULL;
	return istrsenvisxl(mbdstp, NULL, mbsrc, flags, "", NULL);
}

/*
 * 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 characters from src into dst.
 *	This is useful for encoding a block of data.
 */

int
strvisx(char *mbdst, const char *mbsrc, size_t len, int flags)
{
	return istrsenvisx(&mbdst, NULL, mbsrc, len, flags, "", NULL);
}

int
strnvisx(char *mbdst, size_t dlen, const char *mbsrc, size_t len, int flags)
{
	return istrsenvisx(&mbdst, &dlen, mbsrc, len, flags, "", NULL);
}

int
strenvisx(char *mbdst, size_t dlen, const char *mbsrc, size_t len, int flags,
    int *cerr_ptr)
{
	return istrsenvisx(&mbdst, &dlen, mbsrc, len, flags, "", cerr_ptr);
}
#endif