/*      $NetBSD: unvis.c,v 1.44 2014/09/26 15:43:36 roy 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 1.44 2014/09/26 15:43:36 roy Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
__FBSDID("$FreeBSD$");

#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 {
        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;
                default:
                        if (isgraph(c)) {
                                *cp = c;
                                *astate = SS(0, S_GROUND);
                                return UNVIS_VALID;
                        }
                }
                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