/*      $NetBSD: citrus_utf7.c,v 1.5 2006/08/23 12:57:24 tnozaki Exp $  */

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c)2004, 2005 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>

#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>

#include "citrus_namespace.h"
#include "citrus_types.h"
#include "citrus_module.h"
#include "citrus_stdenc.h"
#include "citrus_utf7.h"

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

#define EI_MASK         UINT16_C(0xff)
#define EI_DIRECT       UINT16_C(0x100)
#define EI_OPTION       UINT16_C(0x200)
#define EI_SPACE        UINT16_C(0x400)

typedef struct {
        uint16_t         cell[0x80];
} _UTF7EncodingInfo;

typedef struct {
        unsigned int
                mode: 1,        /* whether base64 mode */
                bits: 4,        /* need to hold 0 - 15 */
                cache: 22;      /* 22 = BASE64_BIT + UTF16_BIT */
        int chlen;
        char ch[4]; /* BASE64_IN, 3 * 6 = 18, most closed to UTF16_BIT */
} _UTF7State;

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

#define _FUNCNAME(m)                    _citrus_UTF7_##m
#define _ENCODING_INFO                  _UTF7EncodingInfo
#define _ENCODING_STATE                 _UTF7State
#define _ENCODING_MB_CUR_MAX(_ei_)              4
#define _ENCODING_IS_STATE_DEPENDENT            1
#define _STATE_NEEDS_EXPLICIT_INIT(_ps_)        0

static __inline void
/*ARGSUSED*/
_citrus_UTF7_init_state(_UTF7EncodingInfo * __restrict ei __unused,
    _UTF7State * __restrict s)
{

        memset((void *)s, 0, sizeof(*s));
}

#if 0
static __inline void
/*ARGSUSED*/
_citrus_UTF7_pack_state(_UTF7EncodingInfo * __restrict ei __unused,
    void *__restrict pspriv, const _UTF7State * __restrict s)
{

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

static __inline void
/*ARGSUSED*/
_citrus_UTF7_unpack_state(_UTF7EncodingInfo * __restrict ei __unused,
    _UTF7State * __restrict s, const void * __restrict pspriv)
{

        memcpy((void *)s, pspriv, sizeof(*s));
}
#endif

static const char base64[] =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "abcdefghijklmnopqrstuvwxyz"
        "0123456789+/";

static const char direct[] =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "abcdefghijklmnopqrstuvwxyz"
        "0123456789'(),-./:?";

static const char option[] = "!\"#$%&*;<=>@[]^_`{|}";
static const char spaces[] = " \t\r\n";

#define BASE64_BIT      6
#define UTF16_BIT       16

#define BASE64_MAX      0x3f
#define UTF16_MAX       UINT16_C(0xffff)
#define UTF32_MAX       UINT32_C(0x10ffff)

#define BASE64_IN       '+'
#define BASE64_OUT      '-'

#define SHIFT7BIT(c)    ((c) >> 7)
#define ISSPECIAL(c)    ((c) == '\0' || (c) == BASE64_IN)

#define FINDLEN(ei, c) \
        (SHIFT7BIT((c)) ? -1 : (((ei)->cell[(c)] & EI_MASK) - 1))

#define ISDIRECT(ei, c) (!SHIFT7BIT((c)) && (ISSPECIAL((c)) || \
        ei->cell[(c)] & (EI_DIRECT | EI_OPTION | EI_SPACE)))

#define ISSAFE(ei, c)   (!SHIFT7BIT((c)) && (ISSPECIAL((c)) || \
        (c < 0x80 && ei->cell[(c)] & (EI_DIRECT | EI_SPACE))))

/* surrogate pair */
#define SRG_BASE        UINT32_C(0x10000)
#define HISRG_MIN       UINT16_C(0xd800)
#define HISRG_MAX       UINT16_C(0xdbff)
#define LOSRG_MIN       UINT16_C(0xdc00)
#define LOSRG_MAX       UINT16_C(0xdfff)

static int
_citrus_UTF7_mbtoutf16(_UTF7EncodingInfo * __restrict ei,
    uint16_t * __restrict u16, char ** __restrict s, size_t n,
    _UTF7State * __restrict psenc, size_t * __restrict nresult)
{
        char *s0;
        int done, i, len;

        *nresult = 0;
        s0 = *s;

        for (i = 0, done = 0; done == 0; i++) {
                if (i == psenc->chlen) {
                        if (n-- < 1) {
                                *nresult = (size_t)-2;
                                *s = s0;
                                return (0);
                        }
                        psenc->ch[psenc->chlen++] = *s0++;
                }
                if (SHIFT7BIT((int)psenc->ch[i]))
                        goto ilseq;
                if (!psenc->mode) {
                        if (psenc->bits > 0 || psenc->cache > 0)
                                return (EINVAL);
                        if (psenc->ch[i] == BASE64_IN)
                                psenc->mode = 1;
                        else {
                                if (!ISDIRECT(ei, (int)psenc->ch[i]))
                                        goto ilseq;
                                *u16 = (uint16_t)psenc->ch[i];
                                done = 1;
                                continue;
                        }
                } else {
                        if (psenc->ch[i] == BASE64_OUT && psenc->cache == 0) {
                                psenc->mode = 0;
                                *u16 = (uint16_t)BASE64_IN;
                                done = 1;
                                continue;
                        }
                        len = FINDLEN(ei, (int)psenc->ch[i]);
                        if (len < 0) {
                                if (psenc->bits >= BASE64_BIT)
                                        return (EINVAL);
                                psenc->mode = 0;
                                psenc->bits = psenc->cache = 0;
                                if (psenc->ch[i] != BASE64_OUT) {
                                        if (!ISDIRECT(ei, (int)psenc->ch[i]))
                                                goto ilseq;
                                        *u16 = (uint16_t)psenc->ch[i];
                                        done = 1;
                                } else {
                                        psenc->chlen--;
                                        i--;
                                }
                        } else {
                                psenc->cache =
                                    (psenc->cache << BASE64_BIT) | len;
                                switch (psenc->bits) {
                                case 0: case 2: case 4: case 6: case 8:
                                        psenc->bits += BASE64_BIT;
                                        break;
                                case 10: case 12: case 14:
                                        psenc->bits -= (UTF16_BIT - BASE64_BIT);
                                        *u16 = (psenc->cache >> psenc->bits) &
                                            UTF16_MAX;
                                        done = 1;
                                        break;
                                default:
                                        return (EINVAL);
                                }
                        }
                }
        }

        if (psenc->chlen > i)
                return (EINVAL);
        psenc->chlen = 0;
        *nresult = (size_t)((*u16 == 0) ? 0 : s0 - *s);
        *s = s0;

        return (0);

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

static int
_citrus_UTF7_mbrtowc_priv(_UTF7EncodingInfo * __restrict ei,
    wchar_t * __restrict pwc, char ** __restrict s, size_t n,
    _UTF7State * __restrict psenc, size_t * __restrict nresult)
{
        uint32_t u32;
        uint16_t hi, lo;
        size_t nr, siz;
        int err;

        if (*s == NULL) {
                _citrus_UTF7_init_state(ei, psenc);
                *nresult = (size_t)_ENCODING_IS_STATE_DEPENDENT;
                return (0);
        }
        err = _citrus_UTF7_mbtoutf16(ei, &hi, s, n, psenc, &nr);
        if (nr == (size_t)-1 || nr == (size_t)-2) {
                *nresult = nr;
                return (err);
        }
        if (err != 0)
                return (err);
        n -= nr;
        siz = nr;
        if (hi < HISRG_MIN || hi > HISRG_MAX) {
                u32 = (uint32_t)hi;
                goto done;
        }
        err = _citrus_UTF7_mbtoutf16(ei, &lo, s, n, psenc, &nr);
        if (nr == (size_t)-1 || nr == (size_t)-2) {
                psenc->chlen = 1; /* make get_state_desc return incomplete */
                *nresult = nr;
                return (err);
        }
        if (err != 0)
                return (err);
        if (lo < LOSRG_MIN || lo > LOSRG_MAX) {
                *nresult = (size_t)-1;
                return (EILSEQ);
        }
        hi -= HISRG_MIN;
        lo -= LOSRG_MIN;
        u32 = (hi << 10 | lo) + SRG_BASE;
        siz += nr;
done:
        if (pwc != NULL)
                *pwc = (wchar_t)u32;
        if (u32 == (uint32_t)0) {
                *nresult = (size_t)0;
                _citrus_UTF7_init_state(ei, psenc);
        } else {
                *nresult = siz;
        }
        return (err);
}

static int
_citrus_UTF7_utf16tomb(_UTF7EncodingInfo * __restrict ei,
    char * __restrict s, size_t n __unused, uint16_t u16,
    _UTF7State * __restrict psenc, size_t * __restrict nresult)
{
        int bits, i;

        if (psenc->chlen != 0 || psenc->bits > BASE64_BIT)
                return (EINVAL);

        if (ISSAFE(ei, u16)) {
                if (psenc->mode) {
                        if (psenc->bits > 0) {
                                bits = BASE64_BIT - psenc->bits;
                                i = (psenc->cache << bits) & BASE64_MAX;
                                psenc->ch[psenc->chlen++] = base64[i];
                                psenc->bits = psenc->cache = 0;
                        }
                        if (u16 == BASE64_OUT || FINDLEN(ei, u16) >= 0)
                                psenc->ch[psenc->chlen++] = BASE64_OUT;
                        psenc->mode = 0;
                }
                if (psenc->bits != 0)
                        return (EINVAL);
                psenc->ch[psenc->chlen++] = (char)u16;
                if (u16 == BASE64_IN)
                        psenc->ch[psenc->chlen++] = BASE64_OUT;
        } else {
                if (!psenc->mode) {
                        if (psenc->bits > 0)
                                return (EINVAL);
                        psenc->ch[psenc->chlen++] = BASE64_IN;
                        psenc->mode = 1;
                }
                psenc->cache = (psenc->cache << UTF16_BIT) | u16;
                bits = UTF16_BIT + psenc->bits;
                psenc->bits = bits % BASE64_BIT;
                while ((bits -= BASE64_BIT) >= 0) {
                        i = (psenc->cache >> bits) & BASE64_MAX;
                        psenc->ch[psenc->chlen++] = base64[i];
                }
        }
        memcpy(s, psenc->ch, psenc->chlen);
        *nresult = psenc->chlen;
        psenc->chlen = 0;

        return (0);
}

static int
_citrus_UTF7_wcrtomb_priv(_UTF7EncodingInfo * __restrict ei,
    char * __restrict s, size_t n, wchar_t wchar,
    _UTF7State * __restrict psenc, size_t * __restrict nresult)
{
        uint32_t u32;
        uint16_t u16[2];
        int err, i, len;
        size_t nr, siz;

        u32 = (uint32_t)wchar;
        if (u32 <= UTF16_MAX) {
                u16[0] = (uint16_t)u32;
                len = 1;
        } else if (u32 <= UTF32_MAX) {
                u32 -= SRG_BASE;
                u16[0] = (u32 >> 10) + HISRG_MIN;
                u16[1] = ((uint16_t)(u32 & UINT32_C(0x3ff))) + LOSRG_MIN;
                len = 2;
        } else {
                *nresult = (size_t)-1;
                return (EILSEQ);
        }
        siz = 0;
        for (i = 0; i < len; ++i) {
                err = _citrus_UTF7_utf16tomb(ei, s, n, u16[i], psenc, &nr);
                if (err != 0)
                        return (err); /* XXX: state has been modified */
                s += nr;
                n -= nr;
                siz += nr;
        }
        *nresult = siz;

        return (0);
}

static int
/* ARGSUSED */
_citrus_UTF7_put_state_reset(_UTF7EncodingInfo * __restrict ei __unused,
    char * __restrict s, size_t n, _UTF7State * __restrict psenc,
    size_t * __restrict nresult)
{
        int bits, pos;

        if (psenc->chlen != 0 || psenc->bits > BASE64_BIT)
                return (EINVAL);

        if (psenc->mode) {
                if (psenc->bits > 0) {
                        if (n-- < 1)
                                return (E2BIG);
                        bits = BASE64_BIT - psenc->bits;
                        pos = (psenc->cache << bits) & BASE64_MAX;
                        psenc->ch[psenc->chlen++] = base64[pos];
                        psenc->ch[psenc->chlen++] = BASE64_OUT;
                        psenc->bits = psenc->cache = 0;
                }
                psenc->mode = 0;
        }
        if (psenc->bits != 0)
                return (EINVAL);
        if (n-- < 1)
                return (E2BIG);

        *nresult = (size_t)psenc->chlen;
        if (psenc->chlen > 0) {
                memcpy(s, psenc->ch, psenc->chlen);
                psenc->chlen = 0;
        }

        return (0);
}

static __inline int
/*ARGSUSED*/
_citrus_UTF7_stdenc_wctocs(_UTF7EncodingInfo * __restrict ei __unused,
    _csid_t * __restrict csid, _index_t * __restrict idx, wchar_t wc)
{

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

        return (0);
}

static __inline int
/*ARGSUSED*/
_citrus_UTF7_stdenc_cstowc(_UTF7EncodingInfo * __restrict ei __unused,
    wchar_t * __restrict wc, _csid_t csid, _index_t idx)
{

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

        return (0);
}

static __inline int
/*ARGSUSED*/
_citrus_UTF7_stdenc_get_state_desc_generic(_UTF7EncodingInfo * __restrict ei __unused,
    _UTF7State * __restrict psenc, int * __restrict rstate)
{

        *rstate = (psenc->chlen == 0) ? _STDENC_SDGEN_INITIAL :
            _STDENC_SDGEN_INCOMPLETE_CHAR;
        return (0);
}

static void
/*ARGSUSED*/
_citrus_UTF7_encoding_module_uninit(_UTF7EncodingInfo *ei __unused)
{

        /* ei seems to be unused */
}

static int
/*ARGSUSED*/
_citrus_UTF7_encoding_module_init(_UTF7EncodingInfo * __restrict ei,
    const void * __restrict var __unused, size_t lenvar __unused)
{
        const char *s;

        memset(ei, 0, sizeof(*ei));

#define FILL(str, flag)                         \
do {                                            \
        for (s = str; *s != '\0'; s++)          \
                ei->cell[*s & 0x7f] |= flag;    \
} while (/*CONSTCOND*/0)

        FILL(base64, (s - base64) + 1);
        FILL(direct, EI_DIRECT);
        FILL(option, EI_OPTION);
        FILL(spaces, EI_SPACE);

        return (0);
}

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

_CITRUS_STDENC_DECLS(UTF7);
_CITRUS_STDENC_DEF_OPS(UTF7);

#include "citrus_stdenc_template.h"