/*      $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: head/contrib/libc-vis/vis.c 326307 2017-11-28 01:35:28Z brooks $");
#define _DIAGASSERT(x)  assert(x)
#endif

#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 <stdint.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
#if !defined(__NetBSD__) && !defined(__HAIKU__)
/*
 * 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.
 */
#if defined(__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)(((uint32_t)(u_char)c >> 6) & 03) + L'0';
                *dst++ = (u_char)(((uint32_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 = 0;
        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 * 8 /* 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 = 0;
        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, 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 * 8 /* 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