/* $NetBSD: citrus_ues.c,v 1.5 2022/04/19 20:32:14 rillig Exp $ */

/*-
 * Copyright (c)2006 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_ues.c,v 1.5 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 <stdint.h>
#include <stdlib.h>
#include <limits.h>
#include <wchar.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_ues.h"

typedef struct {
        int mode;
#define MODE_C99        1
        size_t mb_cur_max;
} _UESEncodingInfo;

typedef struct {
        int chlen;
        char ch[12];
} _UESState;

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

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

#define _FUNCNAME(m)                    _citrus_UES_##m
#define _ENCODING_INFO                  _UESEncodingInfo
#define _CTYPE_INFO                     _UESCTypeInfo
#define _ENCODING_STATE                 _UESState
#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_UES_init_state(_UESEncodingInfo * __restrict ei,
        _UESState * __restrict psenc)
{
        psenc->chlen = 0;
}

static __inline void
/*ARGSUSED*/
_citrus_UES_pack_state(_UESEncodingInfo * __restrict ei,
        void *__restrict pspriv, const _UESState * __restrict psenc)
{
        /* ei seem to be unused */
        _DIAGASSERT(pspriv != NULL);
        _DIAGASSERT(psenc != NULL);

        memcpy(pspriv, (const void *)psenc, sizeof(*psenc));
}

static __inline void
/*ARGSUSED*/
_citrus_UES_unpack_state(_UESEncodingInfo * __restrict ei,
        _UESState * __restrict psenc, const void * __restrict pspriv)
{
        /* ei seem to be unused */
        _DIAGASSERT(psenc != NULL);
        _DIAGASSERT(pspriv != NULL);

        memcpy((void *)psenc, pspriv, sizeof(*psenc));
}

static __inline int
to_int(int ch)
{
        if (ch >= '0' && ch <= '9')
                return ch - '0';
        else if (ch >= 'A' && ch <= 'F')
                return (ch - 'A') + 10;
        else if (ch >= 'a' && ch <= 'f')
                return (ch - 'a') + 10;
        return -1;
}

#define ESCAPE          '\\'
#define UCS2_ESC        'u'
#define UCS4_ESC        'U'

#define UCS2_BIT        16
#define UCS4_BIT        32
#define BMP_MAX         UINT32_C(0xFFFF)
#define UCS2_MAX        UINT32_C(0x10FFFF)
#define UCS4_MAX        UINT32_C(0x7FFFFFFF)

static const char *xdig = "0123456789abcdef";

static __inline int
to_str(char *s, wchar_t wc, int bit)
{
        char *p;

        p = s;
        *p++ = ESCAPE;
        switch (bit) {
        case UCS2_BIT:
                *p++ = UCS2_ESC;
                break;
        case UCS4_BIT:
                *p++ = UCS4_ESC;
                break;
        default:
                abort();
        }
        do {
                *p++ = xdig[(wc >> (bit -= 4)) & 0xF];
        } while (bit > 0);
        return p - s;
}

static __inline int
is_hi_surrogate(wchar_t wc)
{
        return wc >= 0xD800 && wc <= 0xDBFF;
}

static __inline int
is_lo_surrogate(wchar_t wc)
{
        return wc >= 0xDC00 && wc <= 0xDFFF;
}

static __inline wchar_t
surrogate_to_ucs(wchar_t hi, wchar_t lo)
{
        _DIAGASSERT(is_hi_surrogate(hi));
        _DIAGASSERT(is_lo_surrogate(lo));

        hi -= 0xD800;
        lo -= 0xDC00;
        return (hi << 10 | lo) + 0x10000;
}

static __inline void
ucs_to_surrogate(wchar_t wc, wchar_t * __restrict hi, wchar_t * __restrict lo)
{
        _DIAGASSERT(hi != NULL);
        _DIAGASSERT(lo != NULL);
        _DIAGASSERT(wc >= 0x10000);

        wc -= 0x10000;
        *hi = (wc >> 10) + 0xD800;
        *lo = (wc & 0x3FF) + 0xDC00;
}

static __inline int
is_basic(wchar_t wc)
{
        return (uint32_t)wc <= 0x9F &&
            wc != 0x24 && wc != 0x40 && wc != 0x60;
}

static int
_citrus_UES_mbrtowc_priv(_UESEncodingInfo * __restrict ei,
        wchar_t * __restrict pwc, const char ** __restrict s, size_t n,
        _UESState * __restrict psenc, size_t * __restrict nresult)
{
        const char *s0;
        int ch, head, tail, num;
        wchar_t hi, wc;

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

        if (*s == NULL) {
                _citrus_UES_init_state(ei, psenc);
                *nresult = 0;
                return 0;
        }
        s0 = *s;

        hi = (wchar_t)0;
        tail = 0;

surrogate:
        wc = (wchar_t)0;
        head = tail;
        if (psenc->chlen == head) {
                if (n-- < 1)
                        goto restart;
                psenc->ch[psenc->chlen++] = *s0++;
        }
        ch = (unsigned char)psenc->ch[head++];
        if (ch == ESCAPE) {
                if (psenc->chlen == head) {
                        if (n-- < 1)
                                goto restart;
                        psenc->ch[psenc->chlen++] = *s0++;
                }
                switch (psenc->ch[head]) {
                case UCS2_ESC:
                        tail += 6;
                        break;
                case UCS4_ESC:
                        if (ei->mode & MODE_C99) {
                                tail = 10;
                                break;
                        }
                /*FALLTHROUGH*/
                default:
                        tail = 0;
                }
                ++head;
        }
        for (; head < tail; ++head) {
                if (psenc->chlen == head) {
                        if (n-- < 1) {
restart:
                                *s = s0;
                                *nresult = (size_t)-2;
                                return 0;
                        }
                        psenc->ch[psenc->chlen++] = *s0++;
                }
                num = to_int((int)(unsigned char)psenc->ch[head]);
                if (num < 0) {
                        tail = 0;
                        break;
                }
                wc = (wc << 4) | num;
        }
        head = 0;
        switch (tail) {
        case 0:
                break;
        case 6:
                if (hi != (wchar_t)0)
                        break;
                if ((ei->mode & MODE_C99) == 0) {
                        if (is_hi_surrogate(wc) != 0) {
                                hi = wc;
                                goto surrogate;
                        }
                        if ((uint32_t)wc <= 0x7F /* XXX */ ||
                            is_lo_surrogate(wc) != 0)
                                break;
                        goto done;
                }
        /*FALLTHROUGH*/
        case 10:
                if (is_basic(wc) == 0 && (uint32_t)wc <= UCS4_MAX &&
                    is_hi_surrogate(wc) == 0 && is_lo_surrogate(wc) == 0)
                        goto done;
                *nresult = (size_t)-1;
                return EILSEQ;
        case 12:
                if (is_lo_surrogate(wc) == 0)
                        break;
                wc = surrogate_to_ucs(hi, wc);
                goto done;
        }
        ch = (unsigned char)psenc->ch[0];
        head = psenc->chlen;
        if (--head > 0)
                memmove(&psenc->ch[0], &psenc->ch[1], head);
        wc = (wchar_t)ch;
done:
        psenc->chlen = head;
        if (pwc != NULL)
                *pwc = wc;
        *nresult = (size_t)((wc == 0) ? 0 : (s0 - *s));
        *s = s0;

        return 0;
}

static int
_citrus_UES_wcrtomb_priv(_UESEncodingInfo * __restrict ei,
        char * __restrict s, size_t n, wchar_t wc,
        _UESState * __restrict psenc, size_t * __restrict nresult)
{
        wchar_t hi, lo;

        if (psenc->chlen != 0)
                return EINVAL;

        if ((ei->mode & MODE_C99) ? is_basic(wc) : (uint32_t)wc <= 0x7F) {
                if (n-- < 1)
                        goto e2big;
                psenc->ch[psenc->chlen++] = (char)wc;
        } else if ((uint32_t)wc <= BMP_MAX) {
                if (n < 6)
                        goto e2big;
                psenc->chlen = to_str(&psenc->ch[0], wc, UCS2_BIT);
        } else if ((ei->mode & MODE_C99) == 0 && (uint32_t)wc <= UCS2_MAX) {
                if (n < 12)
                        goto e2big;
                ucs_to_surrogate(wc, &hi, &lo);
                psenc->chlen += to_str(&psenc->ch[0], hi, UCS2_BIT);
                psenc->chlen += to_str(&psenc->ch[6], lo, UCS2_BIT);
        } else if ((ei->mode & MODE_C99) && (uint32_t)wc <= UCS4_MAX) {
                if (n < 10)
                        goto e2big;
                psenc->chlen = to_str(&psenc->ch[0], wc, UCS4_BIT);
        } else {
                *nresult = (size_t)-1;
                return EILSEQ;
        }
        memcpy(s, psenc->ch, psenc->chlen);
        *nresult = psenc->chlen;
        psenc->chlen = 0;

        return 0;

e2big:
        *nresult = (size_t)-1;
        return E2BIG;
}

/*ARGSUSED*/
static int
_citrus_UES_stdenc_wctocs(_UESEncodingInfo * __restrict ei,
        _csid_t * __restrict csid, _index_t * __restrict idx, wchar_t wc)
{
        /* ei seem to be unused */
        _DIAGASSERT(csid != NULL);
        _DIAGASSERT(idx != NULL);

        *csid = 0;
        *idx = (_index_t)wc;

        return 0;
}

static __inline int
/*ARGSUSED*/
_citrus_UES_stdenc_cstowc(_UESEncodingInfo * __restrict ei,
        wchar_t * __restrict wc, _csid_t csid, _index_t idx)
{
        /* ei seem to be unused */
        _DIAGASSERT(wc != NULL);

        if (csid != 0)
                return EILSEQ;
        *wc = (wchar_t)idx;

        return 0;
}

static __inline int
/*ARGSUSED*/
_citrus_UES_stdenc_get_state_desc_generic(_UESEncodingInfo * __restrict ei,
        _UESState * __restrict psenc, int * __restrict rstate)
{
        _DIAGASSERT(psenc != NULL);
        _DIAGASSERT(rstate != NULL);

        if (psenc->chlen == 0)
                *rstate = _STDENC_SDGEN_INITIAL;
        else
                *rstate = _STDENC_SDGEN_INCOMPLETE_CHAR; /* XXX */
 
        return 0;
}

static void
/*ARGSUSED*/
_citrus_UES_encoding_module_uninit(_UESEncodingInfo *ei)
{
        /* ei seems to be unused */
}

static int
/*ARGSUSED*/
_citrus_UES_encoding_module_init(_UESEncodingInfo * __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));
        while (lenvar > 0) {
                switch (_bcs_toupper(*p)) {
                case 'C':
                        MATCH(C99, ei->mode |= MODE_C99);
                        break;
                }
                ++p;
                --lenvar;
        }
        ei->mb_cur_max = (ei->mode & MODE_C99) ? 10 : 12;

        return 0;
}

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

_CITRUS_CTYPE_DECLS(UES);
_CITRUS_CTYPE_DEF_OPS(UES);

#include "citrus_ctype_template.h"

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

_CITRUS_STDENC_DECLS(UES);
_CITRUS_STDENC_DEF_OPS(UES);

#include "citrus_stdenc_template.h"