/*
 * 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 usr/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 usr/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 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Kernel iconv code conversion functions (PSARC/2007/173).
 *
 * Man pages: kiconv_open(9F), kiconv(9F), kiconv_close(9F), and kiconvstr(9F).
 * Interface stability: Committed.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/sysmacros.h>
#include <sys/systm.h>
#include <sys/debug.h>
#include <sys/kmem.h>
#include <sys/sunddi.h>
#include <sys/ksynch.h>
#include <sys/modctl.h>
#include <sys/byteorder.h>
#include <sys/errno.h>
#include <sys/kiconv.h>
#include <sys/kiconv_latin1.h>


/*
 * The following macros indicate ids to the correct code conversion mapping
 * data tables to use. The actual tables are coming from <sys/kiconv_latin1.h>.
 */
#define KICONV_TBLID_1252               (0x00)
#define KICONV_TBLID_8859_1             (0x01)
#define KICONV_TBLID_8859_15            (0x02)
#define KICONV_TBLID_850                (0x03)

#define KICONV_MAX_MAPPING_TBLID        (0x03)

/*
 * The following tables are coming from u8_textprep.c. We use them to
 * check on validity of UTF-8 characters and their bytes.
 */
extern const int8_t u8_number_of_bytes[];
extern const uint8_t u8_valid_min_2nd_byte[];
extern const uint8_t u8_valid_max_2nd_byte[];


/*
 * The following four functions, open_to_1252(), open_to_88591(),
 * open_to_885915(), and open_to_850(), are kiconv_open functions from
 * UTF-8 to corresponding single byte codesets.
 */
static void *
open_to_1252()
{
        kiconv_state_t s;

        s = (kiconv_state_t)kmem_alloc(sizeof (kiconv_state_data_t), KM_SLEEP);
        s->id = KICONV_TBLID_1252;
        s->bom_processed = 0;

        return ((void *)s);
}

static void *
open_to_88591()
{
        kiconv_state_t s;

        s = (kiconv_state_t)kmem_alloc(sizeof (kiconv_state_data_t), KM_SLEEP);
        s->id = KICONV_TBLID_8859_1;
        s->bom_processed = 0;

        return ((void *)s);
}

static void *
open_to_885915()
{
        kiconv_state_t s;

        s = (kiconv_state_t)kmem_alloc(sizeof (kiconv_state_data_t), KM_SLEEP);
        s->id = KICONV_TBLID_8859_15;
        s->bom_processed = 0;

        return ((void *)s);
}

static void *
open_to_850()
{
        kiconv_state_t s;

        s = (kiconv_state_t)kmem_alloc(sizeof (kiconv_state_data_t), KM_SLEEP);
        s->id = KICONV_TBLID_850;
        s->bom_processed = 0;

        return ((void *)s);
}

/*
 * The following four functions, open_fr_1252(), open_fr_88591(),
 * open_fr_885915(), and open_fr_850(), are kiconv_open functions from
 * corresponding single byte codesets to UTF-8.
 */
static void *
open_fr_1252()
{
        return ((void *)KICONV_TBLID_1252);
}

static void *
open_fr_88591()
{
        return ((void *)KICONV_TBLID_8859_1);
}

static void *
open_fr_885915()
{
        return ((void *)KICONV_TBLID_8859_15);
}

static void *
open_fr_850()
{
        return ((void *)KICONV_TBLID_850);
}

/*
 * The following close_to_sb() function is kiconv_close function for
 * the conversions from UTF-8 to single byte codesets. The close_fr_sb()
 * is kiconv_close function for the conversions from single byte codesets to
 * UTF-8.
 */
static int
close_to_sb(void *s)
{
        if (! s || s == (void *)-1)
                return (EBADF);

        kmem_free(s, sizeof (kiconv_state_data_t));

        return (0);
}

static int
close_fr_sb(void *s)
{
        if ((ulong_t)s > KICONV_MAX_MAPPING_TBLID)
                return (EBADF);

        return (0);
}

/*
 * The following is the common kiconv function for conversions from UTF-8
 * to single byte codesets.
 */
static size_t
kiconv_to_sb(void *kcd, char **inbuf, size_t *inbytesleft, char **outbuf,
        size_t *outbytesleft, int *errno)
{
        size_t id;
        size_t ret_val;
        uchar_t *ib;
        uchar_t *oldib;
        uchar_t *ob;
        uchar_t *ibtail;
        uchar_t *obtail;
        uint32_t u8;
        size_t i;
        size_t l;
        size_t h;
        size_t init_h;
        int8_t sz;
        boolean_t second;

        /* Check on the kiconv code conversion descriptor. */
        if (! kcd || kcd == (void *)-1) {
                *errno = EBADF;
                return ((size_t)-1);
        }

        /*
         * Get the table id we are going to use for the code conversion
         * and let's double check on it.
         */
        id = ((kiconv_state_t)kcd)->id;
        if (id > KICONV_MAX_MAPPING_TBLID) {
                *errno = EBADF;
                return ((size_t)-1);
        }

        /* If this is a state reset request, process and return. */
        if (! inbuf || ! (*inbuf)) {
                ((kiconv_state_t)kcd)->bom_processed = 0;
                return ((size_t)0);
        }

        ret_val = 0;
        ib = (uchar_t *)*inbuf;
        ob = (uchar_t *)*outbuf;
        ibtail = ib + *inbytesleft;
        obtail = ob + *outbytesleft;

        /*
         * The inital high value for the binary search we will be using
         * shortly is a literal constant as of today but to be future proof,
         * let's calculate it like the following at here.
         */
        init_h = sizeof (to_sb_tbl[id]) / sizeof (kiconv_to_sb_tbl_comp_t) - 1;

        /*
         * If we haven't checked on the UTF-8 signature BOM character in
         * the beginning of the conversion data stream, we check it and if
         * find one, we skip it since we have no use for it.
         */
        if (((kiconv_state_t)kcd)->bom_processed == 0 && (ibtail - ib) >= 3 &&
            *ib == 0xef && *(ib + 1) == 0xbb && *(ib + 2) == 0xbf)
                        ib += 3;
        ((kiconv_state_t)kcd)->bom_processed = 1;

        while (ib < ibtail) {
                sz = u8_number_of_bytes[*ib];
                if (sz <= 0) {
                        *errno = EILSEQ;
                        ret_val = (size_t)-1;
                        break;
                }

                /*
                 * If there is no room to write at the output buffer,
                 * issue E2BIG error.
                 */
                if (ob >= obtail) {
                        *errno = E2BIG;
                        ret_val = (size_t)-1;
                        break;
                }

                /*
                 * If it is a 7-bit ASCII character, we don't need to
                 * process further and we just copy the character over.
                 *
                 * If not, we collect the character bytes up to four bytes,
                 * validate the bytes, and binary search for the corresponding
                 * single byte codeset character byte. If we find it from
                 * the mapping table, we put that into the output buffer;
                 * otherwise, we put a replacement character instead as
                 * a non-identical conversion.
                 */
                if (sz == 1) {
                        *ob++ = *ib++;
                        continue;
                }

                /*
                 * Issue EINVAL error if input buffer has an incomplete
                 * character at the end of the buffer.
                 */
                if ((ibtail - ib) < sz) {
                        *errno = EINVAL;
                        ret_val = (size_t)-1;
                        break;
                }

                /*
                 * We collect UTF-8 character bytes and also check if
                 * this is a valid UTF-8 character without any bogus bytes
                 * based on the latest UTF-8 binary representation.
                 */
                oldib = ib;
                u8 = *ib++;
                second = B_TRUE;
                for (i = 1; i < sz; i++) {
                        if (second) {
                                if (*ib < u8_valid_min_2nd_byte[u8] ||
                                    *ib > u8_valid_max_2nd_byte[u8]) {
                                        *errno = EILSEQ;
                                        ret_val = (size_t)-1;
                                        ib = oldib;
                                        goto TO_SB_ILLEGAL_CHAR_ERR;
                                }
                                second = B_FALSE;
                        } else if (*ib < 0x80 || *ib > 0xbf) {
                                *errno = EILSEQ;
                                ret_val = (size_t)-1;
                                ib = oldib;
                                goto TO_SB_ILLEGAL_CHAR_ERR;
                        }
                        u8 = (u8 << 8) | ((uint32_t)*ib);
                        ib++;
                }

                i = l = 0;
                h = init_h;
                while (l <= h) {
                        i = (l + h) / 2;
                        if (to_sb_tbl[id][i].u8 == u8)
                                break;
                        else if (to_sb_tbl[id][i].u8 < u8)
                                l = i + 1;
                        else
                                h = i - 1;
                }

                if (to_sb_tbl[id][i].u8 == u8) {
                        *ob++ = to_sb_tbl[id][i].sb;
                } else {
                        /*
                         * If we don't find a character in the target
                         * codeset, we insert an ASCII replacement character
                         * at the output buffer and indicate such
                         * "non-identical" conversion by increasing the
                         * return value which is the non-identical conversion
                         * counter if bigger than 0.
                         */
                        *ob++ = KICONV_ASCII_REPLACEMENT_CHAR;
                        ret_val++;
                }
        }

TO_SB_ILLEGAL_CHAR_ERR:
        *inbuf = (char *)ib;
        *inbytesleft = ibtail - ib;
        *outbuf = (char *)ob;
        *outbytesleft = obtail - ob;

        return (ret_val);
}

/*
 * The following is the common kiconv function from single byte codesets to
 * UTF-8.
 */
static size_t
kiconv_fr_sb(void *kcd, char **inbuf, size_t *inbytesleft, char **outbuf,
        size_t *outbytesleft, int *errno)
{
        size_t ret_val;
        uchar_t *ib;
        uchar_t *ob;
        uchar_t *ibtail;
        uchar_t *obtail;
        size_t i;
        size_t k;
        int8_t sz;

        /* Check on the kiconv code conversion descriptor validity. */
        if ((ulong_t)kcd > KICONV_MAX_MAPPING_TBLID) {
                *errno = EBADF;
                return ((size_t)-1);
        }

        /*
         * If this is a state reset request, there is nothing to do and so
         * we just return.
         */
        if (! inbuf || ! (*inbuf))
                return ((size_t)0);

        ret_val = 0;
        ib = (uchar_t *)*inbuf;
        ob = (uchar_t *)*outbuf;
        ibtail = ib + *inbytesleft;
        obtail = ob + *outbytesleft;

        while (ib < ibtail) {
                /*
                 * If this is a 7-bit ASCII character, we just copy over and
                 * that's all we need to do for this character.
                 */
                if (*ib < 0x80) {
                        if (ob >= obtail) {
                                *errno = E2BIG;
                                ret_val = (size_t)-1;
                                break;
                        }

                        *ob++ = *ib++;
                        continue;
                }

                /*
                 * Otherwise, we get the corresponding UTF-8 character bytes
                 * from the mapping table and copy them over.
                 *
                 * We don't need to worry about if the UTF-8 character bytes
                 * at the mapping tables are valid or not since they are good.
                 */
                k = *ib - 0x80;
                sz = u8_number_of_bytes[to_u8_tbl[(ulong_t)kcd][k].u8[0]];

                /*
                 * If sz <= 0, that means we don't have any assigned character
                 * at the code point, k + 0x80, of the single byte codeset
                 * which is the fromcode. In other words, the input buffer
                 * has an illegal character.
                 */
                if (sz <= 0) {
                        *errno = EILSEQ;
                        ret_val = (size_t)-1;
                        break;
                }

                if ((obtail - ob) < sz) {
                        *errno = E2BIG;
                        ret_val = (size_t)-1;
                        break;
                }

                for (i = 0; i < sz; i++)
                        *ob++ = to_u8_tbl[(ulong_t)kcd][k].u8[i];

                ib++;
        }

        *inbuf = (char *)ib;
        *inbytesleft = ibtail - ib;
        *outbuf = (char *)ob;
        *outbytesleft = obtail - ob;

        return (ret_val);
}

/*
 * The following is the common kiconvstr function from UTF-8 to single byte
 * codesets.
 */
static size_t
kiconvstr_to_sb(size_t id, uchar_t *ib, size_t *inlen, uchar_t *ob,
        size_t *outlen, int flag, int *errno)
{
        size_t ret_val;
        uchar_t *oldib;
        uchar_t *ibtail;
        uchar_t *obtail;
        uint32_t u8;
        size_t i;
        size_t l;
        size_t h;
        size_t init_h;
        int8_t sz;
        boolean_t second;
        boolean_t do_not_ignore_null;

        /* Let's make sure that the table id is within the valid boundary. */
        if (id > KICONV_MAX_MAPPING_TBLID) {
                *errno = EBADF;
                return ((size_t)-1);
        }

        ret_val = 0;
        ibtail = ib + *inlen;
        obtail = ob + *outlen;
        do_not_ignore_null = ((flag & KICONV_IGNORE_NULL) == 0);
        init_h = sizeof (to_sb_tbl[id]) / sizeof (kiconv_to_sb_tbl_comp_t) - 1;

        /* Skip any UTF-8 signature BOM character in the beginning. */
        if ((ibtail - ib) >= 3 && *ib == 0xef && *(ib + 1) == 0xbb &&
            *(ib + 2) == 0xbf)
                        ib += 3;

        /*
         * Basically this is pretty much the same as kiconv_to_sb() except
         * that we are now accepting two flag values and doing the processing
         * accordingly.
         */
        while (ib < ibtail) {
                sz = u8_number_of_bytes[*ib];
                if (sz <= 0) {
                        if (flag & KICONV_REPLACE_INVALID) {
                                if (ob >= obtail) {
                                        *errno = E2BIG;
                                        ret_val = (size_t)-1;
                                        break;
                                }

                                ib++;
                                goto STR_TO_SB_REPLACE_INVALID;
                        }

                        *errno = EILSEQ;
                        ret_val = (size_t)-1;
                        break;
                }

                if (*ib == '\0' && do_not_ignore_null)
                        break;

                if (ob >= obtail) {
                        *errno = E2BIG;
                        ret_val = (size_t)-1;
                        break;
                }

                if (sz == 1) {
                        *ob++ = *ib++;
                        continue;
                }

                if ((ibtail - ib) < sz) {
                        if (flag & KICONV_REPLACE_INVALID) {
                                ib = ibtail;
                                goto STR_TO_SB_REPLACE_INVALID;
                        }

                        *errno = EINVAL;
                        ret_val = (size_t)-1;
                        break;
                }

                oldib = ib;
                u8 = *ib++;
                second = B_TRUE;
                for (i = 1; i < sz; i++) {
                        if (second) {
                                if (*ib < u8_valid_min_2nd_byte[u8] ||
                                    *ib > u8_valid_max_2nd_byte[u8]) {
                                        if (flag & KICONV_REPLACE_INVALID) {
                                                ib = oldib + sz;
                                                goto STR_TO_SB_REPLACE_INVALID;
                                        }

                                        *errno = EILSEQ;
                                        ret_val = (size_t)-1;
                                        ib = oldib;
                                        goto STR_TO_SB_ILLEGAL_CHAR_ERR;
                                }
                                second = B_FALSE;
                        } else if (*ib < 0x80 || *ib > 0xbf) {
                                if (flag & KICONV_REPLACE_INVALID) {
                                        ib = oldib + sz;
                                        goto STR_TO_SB_REPLACE_INVALID;
                                }

                                *errno = EILSEQ;
                                ret_val = (size_t)-1;
                                ib = oldib;
                                goto STR_TO_SB_ILLEGAL_CHAR_ERR;
                        }
                        u8 = (u8 << 8) | ((uint32_t)*ib);
                        ib++;
                }

                i = l = 0;
                h = init_h;
                while (l <= h) {
                        i = (l + h) / 2;
                        if (to_sb_tbl[id][i].u8 == u8)
                                break;
                        else if (to_sb_tbl[id][i].u8 < u8)
                                l = i + 1;
                        else
                                h = i - 1;
                }

                if (to_sb_tbl[id][i].u8 == u8) {
                        *ob++ = to_sb_tbl[id][i].sb;
                } else {
STR_TO_SB_REPLACE_INVALID:
                        *ob++ = KICONV_ASCII_REPLACEMENT_CHAR;
                        ret_val++;
                }
        }

STR_TO_SB_ILLEGAL_CHAR_ERR:
        *inlen = ibtail - ib;
        *outlen = obtail - ob;

        return (ret_val);
}

/*
 * The following four functions are entry points recorded at the conv_list[]
 * defined at below.
 */
static size_t
kiconvstr_to_1252(char *inarray, size_t *inlen, char *outarray,
        size_t *outlen, int flag, int *errno)
{
        return (kiconvstr_to_sb(KICONV_TBLID_1252, (uchar_t *)inarray,
            inlen, (uchar_t *)outarray, outlen, flag, errno));
}

static size_t
kiconvstr_to_1(char *inarray, size_t *inlen, char *outarray,
        size_t *outlen, int flag, int *errno)
{
        return (kiconvstr_to_sb(KICONV_TBLID_8859_1, (uchar_t *)inarray,
            inlen, (uchar_t *)outarray, outlen, flag, errno));
}

static size_t
kiconvstr_to_15(char *inarray, size_t *inlen, char *outarray,
        size_t *outlen, int flag, int *errno)
{
        return (kiconvstr_to_sb(KICONV_TBLID_8859_15, (uchar_t *)inarray,
            inlen, (uchar_t *)outarray, outlen, flag, errno));
}

static size_t
kiconvstr_to_850(char *inarray, size_t *inlen, char *outarray,
        size_t *outlen, int flag, int *errno)
{
        return (kiconvstr_to_sb(KICONV_TBLID_850, (uchar_t *)inarray,
            inlen, (uchar_t *)outarray, outlen, flag, errno));
}

/*
 * The following is the common kiconvstr function for conversions from
 * single byte codesets to UTF-8.
 */
static size_t
kiconvstr_fr_sb(size_t id, uchar_t *ib, size_t *inlen, uchar_t *ob,
        size_t *outlen, int flag, int *errno)
{
        size_t ret_val;
        uchar_t *ibtail;
        uchar_t *obtail;
        size_t i;
        size_t k;
        int8_t sz;
        boolean_t do_not_ignore_null;

        ret_val = 0;
        ibtail = ib + *inlen;
        obtail = ob + *outlen;
        do_not_ignore_null = ((flag & KICONV_IGNORE_NULL) == 0);

        while (ib < ibtail) {
                if (*ib == '\0' && do_not_ignore_null)
                        break;

                if (*ib < 0x80) {
                        if (ob >= obtail) {
                                *errno = E2BIG;
                                ret_val = (size_t)-1;
                                break;
                        }
                        *ob++ = *ib++;
                        continue;
                }

                k = *ib - 0x80;
                sz = u8_number_of_bytes[to_u8_tbl[id][k].u8[0]];

                if (sz <= 0) {
                        if (flag & KICONV_REPLACE_INVALID) {
                                if ((obtail - ob) < 3) {
                                        *errno = E2BIG;
                                        ret_val = (size_t)-1;
                                        break;
                                }

                                /* Save KICONV_UTF8_REPLACEMENT_CHAR. */
                                *ob++ = 0xef;
                                *ob++ = 0xbf;
                                *ob++ = 0xbd;
                                ret_val++;
                                ib++;

                                continue;
                        }

                        *errno = EILSEQ;
                        ret_val = (size_t)-1;
                        break;
                }

                if ((obtail - ob) < sz) {
                        *errno = E2BIG;
                        ret_val = (size_t)-1;
                        break;
                }

                for (i = 0; i < sz; i++)
                        *ob++ = to_u8_tbl[id][k].u8[i];

                ib++;
        }

        *inlen = ibtail - ib;
        *outlen = obtail - ob;

        return (ret_val);
}

/*
 * The following four functions are also entry points recorded at
 * the conv_list[] at below.
 */
static size_t
kiconvstr_fr_1252(char *inarray, size_t *inlen, char *outarray,
        size_t *outlen, int flag, int *errno)
{
        return (kiconvstr_fr_sb(KICONV_TBLID_1252, (uchar_t *)inarray,
            inlen, (uchar_t *)outarray, outlen, flag, errno));
}

static size_t
kiconvstr_fr_1(char *inarray, size_t *inlen, char *outarray,
        size_t *outlen, int flag, int *errno)
{
        return (kiconvstr_fr_sb(KICONV_TBLID_8859_1, (uchar_t *)inarray,
            inlen, (uchar_t *)outarray, outlen, flag, errno));
}

static size_t
kiconvstr_fr_15(char *inarray, size_t *inlen, char *outarray,
        size_t *outlen, int flag, int *errno)
{
        return (kiconvstr_fr_sb(KICONV_TBLID_8859_15, (uchar_t *)inarray,
            inlen, (uchar_t *)outarray, outlen, flag, errno));
}

static size_t
kiconvstr_fr_850(char *inarray, size_t *inlen, char *outarray,
        size_t *outlen, int flag, int *errno)
{
        return (kiconvstr_fr_sb(KICONV_TBLID_850, (uchar_t *)inarray,
            inlen, (uchar_t *)outarray, outlen, flag, errno));
}

/*
 * The following static vector contains the normalized code names
 * and their corresponding code ids. They are somewhat arbitrarily ordered
 * based on marketing data available. A code id could repeat for aliases.
 *
 * The vector was generated by using a small utility program called
 * codeidlistgen.c that you can find from PSARC/2007/173/materials/util/.
 *
 * The code ids must be portable, i.e., if needed, you can always generate
 * the code_list[] again with different code ids. You'll also need to
 * update the conv_list[] at below.
 */
#define KICONV_MAX_CODEID_ENTRY         68
#define KICONV_MAX_CODEID               42

static kiconv_code_list_t code_list[KICONV_MAX_CODEID_ENTRY] = {
        { "utf8", 0 },
        { "cp1252", 1 },
        { "1252", 1 },
        { "iso88591", 2 },
        { "iso885915", 3 },
        { "cp850", 4 },
        { "850", 4 },
        { "eucjp", 5 },
        { "eucjpms", 6 },
        { "cp932", 7 },
        { "932", 7 },
        { "shiftjis", 8 },
        { "pck", 8 },
        { "sjis", 8 },
        { "gb18030", 9 },
        { "gbk", 10 },
        { "cp936", 10 },
        { "936", 10 },
        { "euccn", 11 },
        { "euckr", 12 },
        { "unifiedhangul", 13 },
        { "cp949", 13 },
        { "949", 13 },
        { "big5", 14 },
        { "cp950", 14 },
        { "950", 14 },
        { "big5hkscs", 15 },
        { "euctw", 16 },
        { "cp950hkscs", 17 },
        { "cp1250", 18 },
        { "1250", 18 },
        { "iso88592", 19 },
        { "cp852", 20 },
        { "852", 20 },
        { "cp1251", 21 },
        { "1251", 21 },
        { "iso88595", 22 },
        { "koi8r", 23 },
        { "cp866", 24 },
        { "866", 24 },
        { "cp1253", 25 },
        { "1253", 25 },
        { "iso88597", 26 },
        { "cp737", 27 },
        { "737", 27 },
        { "cp1254", 28 },
        { "1254", 28 },
        { "iso88599", 29 },
        { "cp857", 30 },
        { "857", 30 },
        { "cp1256", 31 },
        { "1256", 31 },
        { "iso88596", 32 },
        { "cp720", 33 },
        { "720", 33 },
        { "cp1255", 34 },
        { "1255", 34 },
        { "iso88598", 35 },
        { "cp862", 36 },
        { "862", 36 },
        { "cp1257", 37 },
        { "1257", 37 },
        { "iso885913", 38 },
        { "iso885910", 39 },
        { "iso885911", 40 },
        { "tis620", 40 },
        { "iso88593", 41 },
        { "iso88594", 42 },
};

/*
 * The list of code conversions supported are grouped together per
 * module which will be loaded as needed.
 */
#define KICONV_MAX_CONVERSIONS          84

static kiconv_conv_list_t conv_list[KICONV_MAX_CONVERSIONS] = {
        /* Embedded code conversions: */
        {
                1, 0, KICONV_EMBEDDED,
                open_to_1252, kiconv_to_sb, close_to_sb, kiconvstr_to_1252
        },
        {
                0, 1, KICONV_EMBEDDED,
                open_fr_1252, kiconv_fr_sb, close_fr_sb, kiconvstr_fr_1252
        },
        {
                2, 0, KICONV_EMBEDDED,
                open_to_88591, kiconv_to_sb, close_to_sb, kiconvstr_to_1
        },
        {
                0, 2, KICONV_EMBEDDED,
                open_fr_88591, kiconv_fr_sb, close_fr_sb, kiconvstr_fr_1
        },
        {
                3, 0, KICONV_EMBEDDED,
                open_to_885915, kiconv_to_sb, close_to_sb, kiconvstr_to_15
        },
        {
                0, 3, KICONV_EMBEDDED,
                open_fr_885915, kiconv_fr_sb, close_fr_sb, kiconvstr_fr_15
        },
        {
                4, 0, KICONV_EMBEDDED,
                open_to_850, kiconv_to_sb, close_to_sb, kiconvstr_to_850
        },
        {
                0, 4, KICONV_EMBEDDED,
                open_fr_850, kiconv_fr_sb, close_fr_sb, kiconvstr_fr_850
        },

        /* kiconv_ja module conversions: */
        { 0, 5, KICONV_MODULE_ID_JA, NULL, NULL, NULL, NULL },
        { 5, 0, KICONV_MODULE_ID_JA, NULL, NULL, NULL, NULL },
        { 0, 6, KICONV_MODULE_ID_JA, NULL, NULL, NULL, NULL },
        { 6, 0, KICONV_MODULE_ID_JA, NULL, NULL, NULL, NULL },
        { 0, 7, KICONV_MODULE_ID_JA, NULL, NULL, NULL, NULL },
        { 7, 0, KICONV_MODULE_ID_JA, NULL, NULL, NULL, NULL },
        { 0, 8, KICONV_MODULE_ID_JA, NULL, NULL, NULL, NULL },
        { 8, 0, KICONV_MODULE_ID_JA, NULL, NULL, NULL, NULL },

        /* kiconv_sc module conversions: */
        { 0, 9, KICONV_MODULE_ID_SC, NULL, NULL, NULL, NULL },
        { 9, 0, KICONV_MODULE_ID_SC, NULL, NULL, NULL, NULL },
        { 0, 10, KICONV_MODULE_ID_SC, NULL, NULL, NULL, NULL },
        { 10, 0, KICONV_MODULE_ID_SC, NULL, NULL, NULL, NULL },
        { 0, 11, KICONV_MODULE_ID_SC, NULL, NULL, NULL, NULL },
        { 11, 0, KICONV_MODULE_ID_SC, NULL, NULL, NULL, NULL },

        /* kiconv_ko module conversions: */
        { 0, 12, KICONV_MODULE_ID_KO, NULL, NULL, NULL, NULL },
        { 12, 0, KICONV_MODULE_ID_KO, NULL, NULL, NULL, NULL },
        { 0, 13, KICONV_MODULE_ID_KO, NULL, NULL, NULL, NULL },
        { 13, 0, KICONV_MODULE_ID_KO, NULL, NULL, NULL, NULL },

        /* kiconv_tc module conversions: */
        { 0, 14, KICONV_MODULE_ID_TC, NULL, NULL, NULL, NULL },
        { 14, 0, KICONV_MODULE_ID_TC, NULL, NULL, NULL, NULL },
        { 0, 15, KICONV_MODULE_ID_TC, NULL, NULL, NULL, NULL },
        { 15, 0, KICONV_MODULE_ID_TC, NULL, NULL, NULL, NULL },
        { 0, 16, KICONV_MODULE_ID_TC, NULL, NULL, NULL, NULL },
        { 16, 0, KICONV_MODULE_ID_TC, NULL, NULL, NULL, NULL },
        { 0, 17, KICONV_MODULE_ID_TC, NULL, NULL, NULL, NULL },
        { 17, 0, KICONV_MODULE_ID_TC, NULL, NULL, NULL, NULL },

        /* kiconv_emea module conversions: */
        { 0, 18, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 18, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 19, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 19, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 20, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 20, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 21, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 21, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 22, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 22, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 23, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 23, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 24, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 24, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 25, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 25, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 26, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 26, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 27, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 27, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 28, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 28, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 29, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 29, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 30, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 30, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 31, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 31, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 32, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 32, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 33, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 33, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 34, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 34, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 35, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 35, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 36, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 36, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 37, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 37, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 38, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 38, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 39, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 39, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 40, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 40, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 41, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 41, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 0, 42, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
        { 42, 0, KICONV_MODULE_ID_EMEA, NULL, NULL, NULL, NULL },
};

/* The list of implemeted and supported modules. */
static kiconv_mod_list_t module_list[KICONV_MAX_MODULE_ID + 1] = {
        "kiconv_embedded", 0,
        "kiconv_ja", 0,
        "kiconv_sc", 0,
        "kiconv_ko", 0,
        "kiconv_tc", 0,
        "kiconv_emea", 0,
};

/*
 * We use conv_list_lock to restrict data access of both conv_list[] and
 * module_list[] as they are tightly coupled critical sections that need to be
 * dealt together as a unit.
 */
static kmutex_t conv_list_lock;

void
kiconv_init()
{
        mutex_init(&conv_list_lock, NULL, MUTEX_DEFAULT, NULL);
}

/*
 * The following is used to check on whether a kiconv module is being
 * used or not at the _fini() of the module.
 */
size_t
kiconv_module_ref_count(size_t mid)
{
        int count;

        if (mid <= 0 || mid > KICONV_MAX_MODULE_ID)
                return (0);

        mutex_enter(&conv_list_lock);

        count = module_list[mid].refcount;

        mutex_exit(&conv_list_lock);

        return (count);
}

/*
 * This function "normalizes" a given code name, n, by not including skippable
 * characters and folding uppercase letters to corresponding lowercase letters.
 * We only fold 7-bit ASCII uppercase characters since the names should be in
 * Portable Character Set of 7-bit ASCII.
 *
 * By doing this, we will be able to maximize the code name matches.
 */
static size_t
normalize_codename(const char *n)
{
        char s[KICONV_MAX_CODENAME_LEN + 1];
        size_t i;

        if (n == NULL)
                return ((size_t)-1);

        for (i = 0; *n; n++) {
                if (KICONV_SKIPPABLE_CHAR(*n))
                        continue;

                /* If unreasonably lengthy, we don't support such names. */
                if (i >= KICONV_MAX_CODENAME_LEN)
                        return ((size_t)-1);

                s[i++] = (*n >= 'A' && *n <= 'Z') ? *n - 'A' + 'a' : *n;
        }
        s[i] = '\0';

        /* With the normalized name, find the corresponding codeset id. */
        for (i = 0; i < KICONV_MAX_CODEID_ENTRY; i++)
                if (strcmp(s, code_list[i].name) == 0)
                        return (code_list[i].id);

        /*
         * In future time, we will also have a few more lines of code at below
         * that will deal with other user-created modules' fromcodes and
         * tocodes including aliases in a different vector. For now, we don't
         * support that but only the known names to this project at this time.
         */

        return ((size_t)-1);
}

/*
 * This function called from mod_install() registers supplied code
 * conversions. At this point, it does not honor aliases and hence does not
 * use nowait data field from the kiconv module info data structure.
 */
int
kiconv_register_module(kiconv_module_info_t *info)
{
        size_t mid;
        size_t fid;
        size_t tid;
        size_t i;
        size_t j;
        kiconv_ops_t *op;

        /* Validate the given kiconv module info. */
        if (info == NULL || info->module_name == NULL ||
            info->kiconv_num_convs == 0 || info->kiconv_ops_tbl == NULL)
                return (EINVAL);

        /*
         * Check if this is one of the known modules. At this point,
         * we do not allow user-defined kiconv modules and that'd be for
         * a future project.
         */
        for (mid = 1; mid <= KICONV_MAX_MODULE_ID; mid++)
                if (strcmp(module_list[mid].name, info->module_name) == 0)
                        break;
        if (mid > KICONV_MAX_MODULE_ID)
                return (EINVAL);

        /* Let's register the conversions supplied. */
        mutex_enter(&conv_list_lock);

        /*
         * This is very unlikely situation but by any chance we don't want to
         * register a module that is already in.
         */
        if (module_list[mid].refcount > 0) {
                mutex_exit(&conv_list_lock);
                return (EAGAIN);
        }

        for (i = 0; i < info->kiconv_num_convs; i++) {
                op = &(info->kiconv_ops_tbl[i]);

                fid = normalize_codename(op->fromcode);
                tid = normalize_codename(op->tocode);

                /*
                 * If we find anything wrong in this particular conversion,
                 * we skip this one and continue to the next one. This include
                 * a case where there is a conversion already being assigned
                 * into the conv_list[] somehow, i.e., new one never kicks out
                 * old one.
                 */
                if (op->kiconv_open == NULL || op->kiconv == NULL ||
                    op->kiconv_close == NULL || op->kiconvstr == NULL)
                        continue;

                for (j = 0; j < KICONV_MAX_CONVERSIONS; j++) {
                        if (conv_list[j].mid == mid &&
                            conv_list[j].fid == fid &&
                            conv_list[j].tid == tid) {
                                if (conv_list[j].open == NULL) {
                                        conv_list[j].open = op->kiconv_open;
                                        conv_list[j].kiconv = op->kiconv;
                                        conv_list[j].close = op->kiconv_close;
                                        conv_list[j].kiconvstr = op->kiconvstr;
                                }
                                break;
                        }
                }
        }

        mutex_exit(&conv_list_lock);

        return (0);
}

/*
 * The following function called during mod_remove() will try to unregister,
 * i.e., clear up conversion function pointers, from the conv_list[] if it
 * can. If there is any code conversions being used, then, the function will
 * just return EBUSY indicating that the module cannot be unloaded.
 */
int
kiconv_unregister_module(kiconv_module_info_t *info)
{
        size_t mid;
        size_t i;

        if (info == NULL || info->module_name == NULL ||
            info->kiconv_num_convs == 0 || info->kiconv_ops_tbl == NULL)
                return (EINVAL);

        for (mid = 1; mid <= KICONV_MAX_MODULE_ID; mid++)
                if (strcmp(module_list[mid].name, info->module_name) == 0)
                        break;
        if (mid > KICONV_MAX_MODULE_ID)
                return (EINVAL);

        mutex_enter(&conv_list_lock);

        /*
         * If any of the conversions are used, then, this module canont be
         * unloaded.
         */
        if (module_list[mid].refcount > 0) {
                mutex_exit(&conv_list_lock);
                return (EBUSY);
        }

        /*
         * Otherwise, we unregister all conversions from this module
         * and be ready for the unloading. At this point, we only care about
         * the conversions we know about with the module.
         */
        for (i = 0; i < KICONV_MAX_CONVERSIONS; i++) {
                if (conv_list[i].mid == mid) {
                        conv_list[i].open = NULL;
                        conv_list[i].kiconv = NULL;
                        conv_list[i].close = NULL;
                        conv_list[i].kiconvstr = NULL;
                }
        }

        mutex_exit(&conv_list_lock);

        return (0);
}

/*
 * The following function check if asked code conversion is available
 * and if necessary, load the corresponding kiconv module that contains
 * the conversion (and others).
 */
static kiconv_t
check_and_load_conversions(const char *tocode, const char *fromcode)
{
        kiconv_t kcd;
        size_t tid;
        size_t fid;
        size_t mid;
        size_t i;

        /* Normalize the given names and find the corresponding code ids. */
        tid = normalize_codename(tocode);
        if (tid == (size_t)-1)
                return ((kiconv_t)-1);

        fid = normalize_codename(fromcode);
        if (fid == (size_t)-1)
                return ((kiconv_t)-1);

        /*
         * Search the conversion.
         *
         * If the conversion isn't supported, just return -1.
         * If the conversion is supported but there is no corresponding
         * module loaded, try to load it and if successful, return
         * a kiconv conversion descriptor memory block.
         *
         * We maintain a reference counter of uint_t for each module.
         */
        mutex_enter(&conv_list_lock);

        for (i = 0; i < KICONV_MAX_CONVERSIONS; i++)
                if (conv_list[i].tid == tid && conv_list[i].fid == fid)
                        break;
        if (i >= KICONV_MAX_CONVERSIONS) {
                mutex_exit(&conv_list_lock);
                return ((kiconv_t)-1);
        }

        mid = conv_list[i].mid;

        if (conv_list[i].open == NULL) {
                mutex_exit(&conv_list_lock);

                if (modload("kiconv", module_list[mid].name) < 0)
                        return ((kiconv_t)-1);

                /*
                 * Let's double check if something happened right after
                 * the modload and/or if the module really has the conversion.
                 */
                mutex_enter(&conv_list_lock);

                if (conv_list[i].open == NULL) {
                        mutex_exit(&conv_list_lock);
                        return ((kiconv_t)-1);
                }
        }

        /*
         * If we got the conversion, we will use the conversion function
         * in the module and so let's increase the module's refcounter
         * so that the module won't be kicked out. (To be more exact and
         * specific, the "refcount" is thus the reference counter of
         * the module functions being used.)
         */
        if (module_list[mid].refcount < UINT_MAX)
                module_list[mid].refcount++;

        mutex_exit(&conv_list_lock);

        kcd = (kiconv_t)kmem_alloc(sizeof (kiconv_data_t), KM_SLEEP);
        kcd->handle = (void *)-1;
        kcd->id = i;

        return (kcd);
}

/*
 * The following are the four "Committed" interfaces.
 */
kiconv_t
kiconv_open(const char *tocode, const char *fromcode)
{
        kiconv_t kcd;
        size_t mid;

        kcd = check_and_load_conversions(tocode, fromcode);
        if (kcd == (kiconv_t)-1)
                return ((kiconv_t)-1);

        kcd->handle = (conv_list[kcd->id].open)();
        if (kcd->handle == (void *)-1) {
                /*
                 * If the conversion couldn't be opened for some reason,
                 * then, we unallocate the kcd and, more importantly, before
                 * that, we also decrease the module reference counter.
                 */
                mid = conv_list[kcd->id].mid;

                mutex_enter(&conv_list_lock);

                if (module_list[mid].refcount > 0)
                        module_list[mid].refcount--;

                mutex_exit(&conv_list_lock);

                kmem_free((void *)kcd, sizeof (kiconv_data_t));

                return ((kiconv_t)-1);
        }

        return (kcd);
}

size_t
kiconv(kiconv_t kcd, char **inbuf, size_t *inbytesleft,
        char **outbuf, size_t *outbytesleft, int *errno)
{
        /* Do some minimum checking on the kiconv conversion descriptor. */
        if (! kcd || kcd == (kiconv_t)-1 || conv_list[kcd->id].kiconv == NULL) {
                *errno = EBADF;
                return ((size_t)-1);
        }

        return ((conv_list[kcd->id].kiconv)(kcd->handle, inbuf, inbytesleft,
            outbuf, outbytesleft, errno));
}

int
kiconv_close(kiconv_t kcd)
{
        int ret;
        size_t mid;

        if (! kcd || kcd == (kiconv_t)-1 || conv_list[kcd->id].close == NULL)
                return (EBADF);

        mid = conv_list[kcd->id].mid;

        ret = (conv_list[kcd->id].close)(kcd->handle);

        kmem_free((void *)kcd, sizeof (kiconv_data_t));

        mutex_enter(&conv_list_lock);

        /*
         * While we maintain reference conter for each module, once loaded,
         * we don't modunload from kiconv functions even if the counter
         * reaches back to zero.
         */
        if (module_list[mid].refcount > 0)
                module_list[mid].refcount--;

        mutex_exit(&conv_list_lock);

        return (ret);
}

size_t
kiconvstr(const char *tocode, const char *fromcode, char *inarray,
        size_t *inlen, char *outarray, size_t *outlen, int flag, int *errno)
{
        kiconv_t kcd;
        size_t ret;
        size_t mid;

        kcd = check_and_load_conversions(tocode, fromcode);
        if (kcd == (kiconv_t)-1 || conv_list[kcd->id].kiconvstr == NULL) {
                *errno = EBADF;
                return ((size_t)-1);
        }

        mid = conv_list[kcd->id].mid;

        ret = (conv_list[kcd->id].kiconvstr)(inarray, inlen, outarray, outlen,
            flag, errno);

        kmem_free((void *)kcd, sizeof (kiconv_data_t));

        mutex_enter(&conv_list_lock);

        if (module_list[mid].refcount > 0)
                module_list[mid].refcount--;

        mutex_exit(&conv_list_lock);

        return (ret);
}