/* $NetBSD: citrus_gbk2k.c,v 1.9 2022/04/19 20:32:14 rillig Exp $ */

/*-
 * Copyright (c)2003 Citrus Project,
 * 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 AUTHOR 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 AUTHOR 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: citrus_gbk2k.c,v 1.9 2022/04/19 20:32:14 rillig Exp $");
#endif /* LIBC_SCCS and not lint */

#include <assert.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <wchar.h>
#include <sys/types.h>
#include <limits.h>

#include "citrus_namespace.h"
#include "citrus_types.h"
#include "citrus_bcs.h"
#include "citrus_module.h"
#include "citrus_ctype.h"
#include "citrus_stdenc.h"
#include "citrus_gbk2k.h"


/* ----------------------------------------------------------------------
 * private stuffs used by templates
 */

typedef struct _GBK2KState {
        char ch[4];
        int chlen;
} _GBK2KState;

typedef struct {
        int mb_cur_max;
} _GBK2KEncodingInfo;

typedef struct {
        _GBK2KEncodingInfo      ei;
        struct {
                /* for future multi-locale facility */
                _GBK2KState     s_mblen;
                _GBK2KState     s_mbrlen;
                _GBK2KState     s_mbrtowc;
                _GBK2KState     s_mbtowc;
                _GBK2KState     s_mbsrtowcs;
                _GBK2KState     s_mbsnrtowcs;
                _GBK2KState     s_wcrtomb;
                _GBK2KState     s_wcsrtombs;
                _GBK2KState     s_wcsnrtombs;
                _GBK2KState     s_wctomb;
        } states;
} _GBK2KCTypeInfo;

#define _CEI_TO_EI(_cei_)               (&(_cei_)->ei)
#define _CEI_TO_STATE(_cei_, _func_)    (_cei_)->states.s_##_func_

#define _FUNCNAME(m)                    _citrus_GBK2K_##m
#define _ENCODING_INFO                  _GBK2KEncodingInfo
#define _CTYPE_INFO                     _GBK2KCTypeInfo
#define _ENCODING_STATE                 _GBK2KState
#define _ENCODING_MB_CUR_MAX(_ei_)      (_ei_)->mb_cur_max
#define _ENCODING_IS_STATE_DEPENDENT    0
#define _STATE_NEEDS_EXPLICIT_INIT(_ps_)        0

static __inline void
/*ARGSUSED*/
_citrus_GBK2K_init_state(_GBK2KEncodingInfo * __restrict ei,
                         _GBK2KState * __restrict s)
{
        memset(s, 0, sizeof(*s));
}

static __inline void
/*ARGSUSED*/
_citrus_GBK2K_pack_state(_GBK2KEncodingInfo * __restrict ei,
                         void * __restrict pspriv,
                         const _GBK2KState * __restrict s)
{
        memcpy(pspriv, (const void *)s, sizeof(*s));
}

static __inline void
/*ARGSUSED*/
_citrus_GBK2K_unpack_state(_GBK2KEncodingInfo * __restrict ei,
                           _GBK2KState * __restrict s,
                           const void * __restrict pspriv)
{
        memcpy((void *)s, pspriv, sizeof(*s));
}

static  __inline int
_mb_singlebyte(int c)
{
        c &= 0xff;
        return (c <= 0x7f);
}

static __inline int
_mb_leadbyte(int c)
{
        c &= 0xff;
        return (0x81 <= c && c <= 0xfe);
}

static __inline int
_mb_trailbyte(int c)
{
        c &= 0xff;
        return ((0x40 <= c && c <= 0x7e) || (0x80 <= c && c <= 0xfe));
}

static __inline int
_mb_surrogate(int c)
{
        c &= 0xff;
        return (0x30 <= c && c <= 0x39);
}

static __inline int
_mb_count(wchar_t v)
{
        u_int32_t c;

        c = (u_int32_t)v; /* XXX */
        if (!(c & 0xffffff00))
                return (1);
        if (!(c & 0xffff0000))
                return (2);
        return (4);
}

#define _PSENC          (psenc->ch[psenc->chlen - 1])
#define _PUSH_PSENC(c)  (psenc->ch[psenc->chlen++] = (c))

static int
_citrus_GBK2K_mbrtowc_priv(_GBK2KEncodingInfo * __restrict ei,
                           wchar_t * __restrict pwc,
                           const char ** __restrict s, size_t n,
                           _GBK2KState * __restrict psenc,
                           size_t * __restrict nresult)
{
        int chlenbak, len;
        const char *s0, *s1;
        wchar_t wc;

        _DIAGASSERT(ei != NULL);
        /* pwc may be NULL */
        _DIAGASSERT(s != NULL);
        _DIAGASSERT(psenc != NULL);

        s0 = *s;

        if (s0 == NULL) {
                /* _citrus_GBK2K_init_state(ei, psenc); */
                psenc->chlen = 0;
                *nresult = 0;
                return (0);
        }

        chlenbak = psenc->chlen;

        switch (psenc->chlen) {
        case 3:
                if (!_mb_leadbyte (_PSENC))
                        goto invalid;
        /* FALLTHROUGH */
        case 2:
                if (!_mb_surrogate(_PSENC) || _mb_trailbyte(_PSENC))
                        goto invalid;
        /* FALLTHROUGH */
        case 1:
                if (!_mb_leadbyte (_PSENC))
                        goto invalid;
        /* FALLTHOROUGH */
        case 0:
                break;
        default:
                goto invalid;
        }

        for (;;) {
                if (n-- < 1)
                        goto restart;

                _PUSH_PSENC(*s0++);

                switch (psenc->chlen) {
                case 1:
                        if (_mb_singlebyte(_PSENC))
                                goto convert;
                        if (_mb_leadbyte  (_PSENC))
                                continue;
                        goto ilseq;
                case 2:
                        if (_mb_trailbyte (_PSENC))
                                goto convert;
                        if (ei->mb_cur_max == 4 &&
                            _mb_surrogate (_PSENC))
                                continue;
                        goto ilseq;
                case 3:
                        if (_mb_leadbyte  (_PSENC))
                                continue;
                        goto ilseq;
                case 4:
                        if (_mb_surrogate (_PSENC))
                                goto convert;
                        goto ilseq;
                }
        }

convert:
        len = psenc->chlen;
        s1  = &psenc->ch[0];
        wc  = 0;
        while (len-- > 0)
                wc = (wc << 8) | (*s1++ & 0xff);

        if (pwc != NULL)
                *pwc = wc;
        *s = s0;
        *nresult = (wc == 0) ? 0 : psenc->chlen - chlenbak; 
        /* _citrus_GBK2K_init_state(ei, psenc); */
        psenc->chlen = 0;

        return (0);

restart:
        *s = s0;
        *nresult = (size_t)-2;

        return (0);

invalid:
        return (EINVAL);

ilseq:
        *nresult = (size_t)-1;
        return (EILSEQ);
}

static int
_citrus_GBK2K_wcrtomb_priv(_GBK2KEncodingInfo * __restrict ei,
                           char * __restrict s, size_t n, wchar_t wc,
                           _GBK2KState * __restrict psenc,
                           size_t * __restrict nresult)
{
        int len, ret;

        _DIAGASSERT(ei != NULL);
        _DIAGASSERT(s != NULL);
        _DIAGASSERT(psenc != NULL);

        if (psenc->chlen != 0) {
                ret = EINVAL;
                goto err;
        }

        len = _mb_count(wc);
        if (n < len) {
                ret = E2BIG;
                goto err;
        }

        switch (len) {
        case 1:
                if (!_mb_singlebyte(_PUSH_PSENC(wc     ))) {
                        ret = EILSEQ;
                        goto err;
                }
                break;
        case 2:
                if (!_mb_leadbyte  (_PUSH_PSENC(wc >> 8)) ||
                    !_mb_trailbyte (_PUSH_PSENC(wc     ))) {
                        ret = EILSEQ;
                        goto err;
                }
                break;
        case 4:
                if (ei->mb_cur_max != 4 ||
                    !_mb_leadbyte  (_PUSH_PSENC(wc >> 24)) ||
                    !_mb_surrogate (_PUSH_PSENC(wc >> 16)) ||
                    !_mb_leadbyte  (_PUSH_PSENC(wc >>  8)) ||
                    !_mb_surrogate (_PUSH_PSENC(wc      ))) {
                        ret = EILSEQ;
                        goto err;
                }
                break;
        }

        _DIAGASSERT(len == psenc->chlen);

        memcpy(s, psenc->ch, psenc->chlen);
        *nresult = psenc->chlen;
        /* _citrus_GBK2K_init_state(ei, psenc); */
        psenc->chlen = 0;

        return (0);

err:
        *nresult = (size_t)-1;
        return ret;
}

static __inline int
/*ARGSUSED*/
_citrus_GBK2K_stdenc_wctocs(_GBK2KEncodingInfo * __restrict ei,
                            _csid_t * __restrict csid,
                            _index_t * __restrict idx, wchar_t wc)
{
        u_int8_t ch, cl;

        _DIAGASSERT(csid != NULL && idx != NULL);

        if ((u_int32_t)wc<0x80) {
                /* ISO646 */
                *csid = 0;
                *idx = (_index_t)wc;
        } else if ((u_int32_t)wc>=0x10000) {
                /* GBKUCS : XXX */
                *csid = 3;
                *idx = (_index_t)wc;
        } else {
                ch = (u_int8_t)(wc >> 8);
                cl = (u_int8_t)wc;
                if (ch>=0xA1 && cl>=0xA1) {
                        /* EUC G1 */
                        *csid = 1;
                        *idx = (_index_t)wc & 0x7F7FU;
                } else {
                        /* extended area (0x8140-) */
                        *csid = 2;
                        *idx = (_index_t)wc;
                }
        }
                
        return 0;
}

static __inline int
/*ARGSUSED*/
_citrus_GBK2K_stdenc_cstowc(_GBK2KEncodingInfo * __restrict ei,
                            wchar_t * __restrict wc,
                            _csid_t csid, _index_t idx)
{

        _DIAGASSERT(wc != NULL);

        switch (csid) {
        case 0:
                /* ISO646 */
                *wc = (wchar_t)idx;
                break;
        case 1:
                /* EUC G1 */
                *wc = (wchar_t)idx | 0x8080U;
                break;
        case 2:
                /* extended area */
                *wc = (wchar_t)idx;
                break;
        case 3:
                /* GBKUCS : XXX */
                if (ei->mb_cur_max != 4)
                        return EINVAL;
                *wc = (wchar_t)idx;
                break;
        default:
                return EILSEQ;
        }

        return 0;
}

static __inline int
/*ARGSUSED*/
_citrus_GBK2K_stdenc_get_state_desc_generic(_GBK2KEncodingInfo * __restrict ei,
                                            _GBK2KState * __restrict psenc,
                                            int * __restrict rstate)
{

        if (psenc->chlen == 0)
                *rstate = _STDENC_SDGEN_INITIAL;
        else
                *rstate = _STDENC_SDGEN_INCOMPLETE_CHAR;

        return 0;
}

static int
/*ARGSUSED*/
_citrus_GBK2K_encoding_module_init(_GBK2KEncodingInfo * __restrict ei,
                                   const void * __restrict var, size_t lenvar)
{
        const char *p;

        _DIAGASSERT(ei != NULL);

        p = var;
#define MATCH(x, act)                                           \
do {                                                            \
        if (lenvar >= (sizeof(#x)-1) &&                         \
            _bcs_strncasecmp(p, #x, sizeof(#x)-1) == 0) {       \
                act;                                            \
                lenvar -= sizeof(#x)-1;                         \
                p += sizeof(#x)-1;                              \
        }                                                       \
} while (0)
        memset((void *)ei, 0, sizeof(*ei));
        ei->mb_cur_max = 4;
        while (lenvar>0) {
                switch (_bcs_tolower(*p)) {
                case '2':
                        MATCH("2byte", ei->mb_cur_max = 2);
                        break;
                }
                p++;
                lenvar--;
        }

        return (0);
}

static void
/*ARGSUSED*/
_citrus_GBK2K_encoding_module_uninit(_GBK2KEncodingInfo *ei)
{
}


/* ----------------------------------------------------------------------
 * public interface for ctype
 */

_CITRUS_CTYPE_DECLS(GBK2K);
_CITRUS_CTYPE_DEF_OPS(GBK2K);

#include "citrus_ctype_template.h"

/* ----------------------------------------------------------------------
 * public interface for stdenc
 */

_CITRUS_STDENC_DECLS(GBK2K);
_CITRUS_STDENC_DEF_OPS(GBK2K);

#include "citrus_stdenc_template.h"