/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 1994-2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <euc.h>
#include "japanese.h"

/*
 * struct _cv_state; to keep status
 */
struct _icv_state {
        int     _st_cset;
        int     _st_cset_sav;
};

static unsigned short lookuptbl(unsigned short);

void *
_icv_open()
{
        struct _icv_state *st;

        if ((st = (struct _icv_state *)malloc(sizeof (struct _icv_state)))
                                                                        == NULL)
                return ((void *)ERR_RETURN);

        st->_st_cset = st->_st_cset_sav = CS_0;

        return (st);
}

void
_icv_close(struct _icv_state *st)
{
        free(st);
}

size_t
_icv_iconv(struct _icv_state *st, char **inbuf, size_t *inbytesleft,
                                char **outbuf, size_t *outbytesleft)
{
        int             cset;
        int             stat = ST_INIT;
        unsigned char   *op, ic;
        char            *ip;
        size_t          ileft, oleft;
        size_t          retval;
#ifdef  RFC1468_MODE
        unsigned short  zenkaku;
#endif

        /*
         * If inbuf or *inbuf is NULL, reset conversion descriptor
         * and put escape sequence if needed.
         */
        if ((inbuf == NULL) || (*inbuf == NULL)) {
                st->_st_cset_sav = st->_st_cset = CS_0;
                return ((size_t)0);
        }

        cset = st->_st_cset;

        ip = *inbuf;
        op = (unsigned char *)*outbuf;
        ileft = *inbytesleft;
        oleft = *outbytesleft;

        /*
         * Main loop; basically 1 loop per 1 input byte
         */

        while ((int)ileft > 0) {
                GET(ic);
                if (stat == ST_INIT) {
                        goto text;
                }
                /*
                 *  Half way of Kanji or ESC sequence
                 */
                if (stat == ST_ESC) {
                        if (ic == MBTOG0_1) {
                                if ((int)ileft > 0) {
                                        stat = ST_MBTOG0_1;
                                        continue;
                                } else {
                                        UNGET();
                                        UNGET();
                                        errno = EINVAL;
                                        retval = (size_t)ERR_RETURN;
                                        goto ret;
                                }
                        } else if (ic == SBTOG0_1) {
                                if ((int)ileft > 0) {
                                        stat = ST_SBTOG0;
                                        continue;
                                } else {
                                        UNGET();
                                        UNGET();
                                        errno = EINVAL;
                                        retval = (size_t)ERR_RETURN;
                                        goto ret;
                                }
                        } else if (ic == X208REV_1) {
                                if ((int)ileft > 0) {
                                        stat = ST_208REV_1;
                                        continue;
                                } else {
                                        UNGET();
                                        UNGET();
                                        errno = EINVAL;
                                        retval = (size_t)ERR_RETURN;
                                        goto ret;
                                }
                        } else {
                                UNGET();
                                UNGET();
                                errno = EILSEQ;
                                retval = (size_t)ERR_RETURN;
                                goto ret;
                        }
                } else if (stat == ST_MBTOG0_1) {
                        if ((ic == F_X0208_83_90) || (ic == F_X0208_78)) {
                                stat = ST_INIT;
                                st->_st_cset_sav = cset = CS_1;
                                continue;
                        } else if (ic == MBTOG0_2) {
                                if ((int)ileft > 0) {
                                        stat = ST_MBTOG0_2;
                                        continue;
                                } else {
                                        UNGET();
                                        UNGET();
                                        UNGET();
                                        errno = EINVAL;
                                        retval = (size_t)ERR_RETURN;
                                        goto ret;
                                }
                        } else if (ic == F_X0212_90) {
                                stat = ST_INIT;
                                st->_st_cset_sav = cset = CS_3;
                                continue;
                        } else {
                                UNGET();
                                UNGET();
                                UNGET();
                                errno = EILSEQ;
                                retval = (size_t)ERR_RETURN;
                                goto ret;
                        }
                } else if (stat == ST_MBTOG0_2) {
                        if ((ic == F_X0208_83_90) || (ic == F_X0208_78)) {
                                stat = ST_INIT;
                                st->_st_cset_sav = cset = CS_1;
                                continue;
                        } else if (ic == F_X0212_90) {
                                stat = ST_INIT;
                                st->_st_cset_sav = cset = CS_3;
                                continue;
                        } else {
                                UNGET();
                                UNGET();
                                UNGET();
                                UNGET();
                                errno = EILSEQ;
                                retval = (size_t)ERR_RETURN;
                                goto ret;
                        }
                } else if (stat == ST_SBTOG0) {
                        if ((ic == F_ASCII) ||
                                (ic == F_X0201_RM) ||
                                (ic == F_ISO646)) {
                                stat = ST_INIT;
                                st->_st_cset_sav = cset = CS_0;
                                continue;
                        } if (ic == F_X0201_KN) {
                                st->_st_cset_sav = cset = CS_2;
                                stat = ST_INIT;
                                continue;
                        } else {
                                UNGET();
                                UNGET();
                                UNGET();
                                errno = EILSEQ;
                                retval = (size_t)ERR_RETURN;
                                goto ret;
                        }
                } else if (stat == ST_208REV_1) {
                        if (ic == X208REV_2) {
                                if ((int)ileft > 0) {
                                        stat = ST_208REV_2;
                                        continue;
                                } else {
                                        UNGET();
                                        UNGET();
                                        UNGET();
                                        errno = EINVAL;
                                        retval = (size_t)ERR_RETURN;
                                        goto ret;
                                }
                        } else {
                                UNGET();
                                UNGET();
                                UNGET();
                                errno = EILSEQ;
                                retval = (size_t)ERR_RETURN;
                                goto ret;
                        }
                } else if (stat == ST_208REV_2) {
                        if (ic == ESC) {
                                if ((int)ileft > 0) {
                                        stat = ST_REV_AFT_ESC;
                                        continue;
                                } else {
                                        UNGET();
                                        UNGET();
                                        UNGET();
                                        UNGET();
                                        errno = EINVAL;
                                        retval = (size_t)ERR_RETURN;
                                        goto ret;
                                }
                        } else {
                                UNGET();
                                UNGET();
                                UNGET();
                                UNGET();
                                errno = EILSEQ;
                                retval = (size_t)ERR_RETURN;
                                goto ret;
                        }
                } else if (stat == ST_REV_AFT_ESC) {
                        if (ic == MBTOG0_1) {
                                if ((int)ileft > 0) {
                                        stat = ST_REV_AFT_MBTOG0_1;
                                        continue;
                                } else {
                                        UNGET();
                                        UNGET();
                                        UNGET();
                                        UNGET();
                                        UNGET();
                                        errno = EINVAL;
                                        retval = (size_t)ERR_RETURN;
                                        goto ret;
                                }
                        } else {
                                UNGET();
                                UNGET();
                                UNGET();
                                UNGET();
                                UNGET();
                                errno = EILSEQ;
                                retval = (size_t)ERR_RETURN;
                                goto ret;
                        }
                } else if (stat == ST_REV_AFT_MBTOG0_1) {
                        if (ic == F_X0208_83_90) {
                                stat = ST_INIT;
                                st->_st_cset_sav = cset = CS_1;
                                continue;
                        } else if (ic == MBTOG0_2) {
                                if ((int)ileft > 0) {
                                        stat = ST_REV_AFT_MBTOG0_2;
                                        continue;
                                } else {
                                        UNGET();
                                        UNGET();
                                        UNGET();
                                        UNGET();
                                        UNGET();
                                        UNGET();
                                        errno = EINVAL;
                                        retval = (size_t)ERR_RETURN;
                                        goto ret;
                                }
                        } else {
                                UNGET();
                                UNGET();
                                UNGET();
                                UNGET();
                                UNGET();
                                UNGET();
                                errno = EILSEQ;
                                retval = (size_t)ERR_RETURN;
                                goto ret;
                        }
                } else if (stat == ST_REV_AFT_MBTOG0_2) {
                        if (ic == F_X0208_83_90) {
                                stat = ST_INIT;
                                st->_st_cset_sav = cset = CS_1;
                                continue;
                        } else {
                                UNGET();
                                UNGET();
                                UNGET();
                                UNGET();
                                UNGET();
                                UNGET();
                                UNGET();
                                errno = EILSEQ;
                                retval = (size_t)ERR_RETURN;
                                goto ret;
                        }
                }
text:
                /*
                 * Break through chars or ESC sequence
                 */
                if (ic == ESC) {
                        if ((int)ileft > 0) {
                                stat = ST_ESC;
                                continue;
                        } else {
                                UNGET();
                                errno = EINVAL;
                                retval = (size_t)ERR_RETURN;
                                goto ret;
                        }
                /*
                 * XXX- Because V3 mailtool uses SI/SO to switch
                 *      G0 and G1 sets while it puts "iso2022-7"
                 *      as its "X-Sun-Charset" tag. Though it
                 *      breaks ISO-2022-JP definition based on
                 *      UI-OSF, dtmail have handle them correctly.
                 *      Therefore, we have to following a few codes, UGH.
                 */
                } else if (ic == SO) {
                        cset = CS_2;
                        stat = ST_INIT;
                        continue;
                } else if (ic == SI) {
                        cset = st->_st_cset_sav;
                        stat = ST_INIT;
                        continue;
                }
                if (!(ic & CMSB)) {
                        if (cset == CS_0) {     /* ASCII or JIS roman */
                                CHECK2BIG(SJISW0, 1);
                                PUT(ic);
                                continue;
                        } else if (cset == CS_1) { /* CS_1 Kanji starts */
                                if ((int)ileft > 0) {
                                        int even_ku;
                                        CHECK2BIG(SJISW1, 1);
                                        if ((ic < 0x21) || (ic == 0x7f)) {
                                                UNGET();
                                                errno = EILSEQ;
                                                retval = (size_t)ERR_RETURN;
                                                goto ret;
                                        }
                                        if ((*ip < 0x21) || (*ip == 0x7f)) {
                                                UNGET();
                                                errno = EILSEQ;
                                                retval = (size_t)ERR_RETURN;
                                                goto ret;
                                        }
#ifdef  RFC1468_MODE /* Convert VDC and UDC to GETA */
                                        if ((ic == 0x2d) || (0x75 <= ic)) {
                                                PUT(PGETA >> 8);
                                                GET(ic); /* Get dummy */
                                                PUT(PGETA & 0xff);
                                                continue;
                                        }
#endif  /* RFC1468_MODE */
                                        PUT(jis208tosj1[ic]);
                                        if ((ic % 2) == 0)
                                                even_ku = TRUE;
                                        else
                                                even_ku = FALSE;
                                        GET(ic);
                                        if (even_ku)
                                                ic += 0x80;
                                        PUT(jistosj2[ic]);
                                        continue;
                                } else {        /* input fragment of Kanji */
                                        UNGET();
                                        errno = EINVAL;
                                        retval = (size_t)ERR_RETURN;
                                        goto ret;
                                }
                        } else if (cset == CS_2) { /* Hankaku Katakana */
                                if (!ISSJKANA((ic | CMSB))) {
                                        UNGET();
                                        errno = EILSEQ;
                                        retval = (size_t)ERR_RETURN;
                                        goto ret;
                                }
#ifdef  RFC1468_MODE /* Convert JIS X 0201 kana to PCK zenkaku Kana */
                                CHECK2BIG(SJISW1, 1);
                                zenkaku = halfkana2zenkakus[(ic - 0x21)];
                                ic = (unsigned char)((zenkaku >> 8) & 0xff);
                                PUT(ic);
                                ic = (unsigned char)(zenkaku & 0xff);
                                PUT(ic);
#else   /* ISO-2022-JP.UIOSF */
                                CHECK2BIG(SJISW2, 1);
                                PUT(ic | CMSB);
#endif  /* RFC1468_MODE */
                                continue;
                        } else if (cset == CS_3) { /* CS_3 Kanji starts */
                                unsigned short dest;
                                if ((int)ileft > 0) {
                                        CHECK2BIG(SJISW1, 1);
                                        if ((ic < 0x21) || (ic == 0x7f)) {
                                                UNGET();
                                                errno = EILSEQ;
                                                retval = (size_t)ERR_RETURN;
                                                goto ret;
                                        }
                                        if ((*ip < 0x21) || (*ip == 0x7f)) {
                                                UNGET();
                                                errno = EILSEQ;
                                                retval = (size_t)ERR_RETURN;
                                                goto ret;
                                        }

#ifdef  RFC1468_MODE /* Convert JIS X 0212 to GETA */
                                        PUT(PGETA >> 8);
                                        GET(ic); /* Get dummy */
                                        PUT(PGETA & 0xff);
#else   /* ISO-2022-JP.UIOSF */
                                        if (ic < 0x75) { /* check IBM area */
                                                dest = (ic << 8);
                                                GET(ic);
                                                dest += ic;
                                                dest = lookuptbl(dest);
                                                if (dest == 0xffff) {
                                                        /*
                                                         * Illegal code points
                                                         * in G3 plane.
                                                         */
                                                        UNGET();
                                                        UNGET();
                                                        errno = EILSEQ;
                                                        retval =
                                                        (size_t)ERR_RETURN;
                                                        goto ret;
                                                } else {
                                                        PUT((dest >> 8) & 0xff);
                                                        PUT(dest & 0xff);
                                                }
                                        } else {
                                                int even_ku;

                                                if ((ic % 2) == 0)
                                                        even_ku = TRUE;
                                                else
                                                        even_ku = FALSE;
                                                PUT(jis212tosj1[ic]);
                                                GET(ic);
                                                if (even_ku)
                                                        ic += 0x80;
                                                PUT(jistosj2[ic]);
                                        }
#endif  /* RFC1468_MODE */
                                        continue;
                                } else {        /* input fragment of Kanji */
                                        UNGET();
                                        errno = EINVAL;
                                        retval = (size_t)ERR_RETURN;
                                        goto ret;
                                }
                        }
                } else {
                        UNGET();
                        errno = EILSEQ;
                        retval = (size_t)ERR_RETURN;
                        goto ret;
                }
        }
        retval = ileft;
ret:
        *inbuf = ip;
        *inbytesleft = ileft;
        *outbuf = (char *)op;
        *outbytesleft = oleft;
        st->_st_cset = cset;

        return (retval);
}

/*
 * lookuptbl()
 * Return the index number if its index-ed number
 * is the same as dest value.
 */
static unsigned short
lookuptbl(unsigned short dest)
{
        unsigned short tmp;
        int i;
        int sz = (sizeof (sjtoibmext) / sizeof (sjtoibmext[0]));

        for (i = 0; i < sz; i++) {
                tmp = (sjtoibmext[i] & 0x7f7f);
                if (tmp == dest)
                        return ((i + 0xfa40 + ((i / 0xc0) * 0x40)));
        }
        return (PGETA);
}