/***
*mbrtowc.c - Convert multibyte char to wide char.
*
*       Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
*       Convert a multibyte character into the equivalent wide character.
*
*******************************************************************************/

#include <cruntime.h>
#include <stdlib.h>
#include <errno.h>
#include <dbgint.h>
#include <ctype.h>
#include <internal.h>
#include <internal_securecrt.h>
#include <locale.h>
#include <mtdll.h>
#include <setlocal.h>
#include <wchar.h>
#include <limits.h>              /* for INT_MAX */
#include <stdio.h>               /* for EOF */

/***
*errno_t _mbrtowc_s_l() - Helper function to convert multibyte char to wide character.
*
*Purpose:
*       Convert a multi-byte character into the equivalent wide character,
*       according to the specified LC_CTYPE category, or the current locale.
*       [ANSI].
*
*       NOTE:  Currently, the C libraries support the "C" locale only.
*              Non-C locale support now available under _INTL switch.
*Entry:
*       wchar_t *dst       = pointer to (single) destination wide character
*       const char *s      = pointer to multibyte character
*       size_t n           = maximum length of multibyte character to consider
*       mbstate_t *pmbst   = pointer to state (must be not NULL)
*       _locale_t plocinfo = locale info
*
*Exit:
*       returns, in *pRetValue:
*       If s = NULL, 0, indicating we only use state-independent
*       character encodings.
*       If s != NULL:  0 (if *s = null char)
*                      -1 (if the next n or fewer bytes not valid mbc)
*                      number of bytes comprising converted mbc
*
*Exceptions:
*
*******************************************************************************/

static errno_t __cdecl _mbrtowc_s_l(
    int *pRetValue,
    wchar_t *dst,
    const char *s,
    size_t n,
    mbstate_t *pmbst,
    _locale_t plocinfo
)
{
    _ASSERTE (pmbst != NULL);
    _ASSIGN_IF_NOT_NULL(dst, 0);

    if ( !s || n == 0 )
    {
        /* indicate do not have state-dependent encodings,
            handle zero length string */
        _ASSIGN_IF_NOT_NULL(pRetValue, 0);
        return 0;
    }

    if ( !*s )
    {
        /* handle NULL char */
        _ASSIGN_IF_NOT_NULL(pRetValue, 0);
        return 0;
    }

    _LocaleUpdate _loc_update(plocinfo);
    _ASSERTE (_loc_update.GetLocaleT()->locinfo->mb_cur_max == 1 || _loc_update.GetLocaleT()->locinfo->mb_cur_max == 2);

    if ( _loc_update.GetLocaleT()->locinfo->lc_handle[LC_CTYPE] == _CLOCALEHANDLE )
    {
        _ASSIGN_IF_NOT_NULL(dst, (wchar_t)(unsigned char)*s);
        _ASSIGN_IF_NOT_NULL(pRetValue, 1);
        return 0;
    }

    if (*pmbst != 0)
    {
        /* complete two-byte multibyte character */
        ((char *)pmbst)[1] = *s;
        if (_loc_update.GetLocaleT()->locinfo->mb_cur_max <= 1 ||
            (MultiByteToWideChar(
                _loc_update.GetLocaleT()->locinfo->lc_codepage,
                MB_PRECOMPOSED | MB_ERR_INVALID_CHARS,
                (char *)pmbst,
                2,
                dst,
                (dst != NULL ? 1 : 0)) == 0))
        {
            /* translation failed */
            *pmbst = 0;
            errno = EILSEQ;
            _ASSIGN_IF_NOT_NULL(dst, 0);
            _ASSIGN_IF_NOT_NULL(pRetValue, -1);
            return errno;
        }
        *pmbst = 0;
        _ASSIGN_IF_NOT_NULL(pRetValue, _loc_update.GetLocaleT()->locinfo->mb_cur_max);
        return 0;
    }
    else if ( _isleadbyte_l((unsigned char)*s, _loc_update.GetLocaleT()) )
    {
        /* multi-byte char */
        if (n < (size_t)_loc_update.GetLocaleT()->locinfo->mb_cur_max)
        {   /* save partial multibyte character */
            ((char *)pmbst)[0] = *s;
            _ASSIGN_IF_NOT_NULL(pRetValue, -2);
            return 0;
        }
        else if ( _loc_update.GetLocaleT()->locinfo->mb_cur_max <= 1 ||
                  (MultiByteToWideChar( _loc_update.GetLocaleT()->locinfo->lc_codepage,
                                        MB_PRECOMPOSED | MB_ERR_INVALID_CHARS,
                                        s,
                                        _loc_update.GetLocaleT()->locinfo->mb_cur_max,
                                        dst,
                                        (dst != NULL ? 1 : 0)) == 0) )
        {
            /* validate high byte of mbcs char */
            if (!*(s+1))
            {
                *pmbst = 0;
                errno = EILSEQ;
                _ASSIGN_IF_NOT_NULL(dst, 0);
                _ASSIGN_IF_NOT_NULL(pRetValue, -1);
                return errno;
            }
        }
        _ASSIGN_IF_NOT_NULL(pRetValue, _loc_update.GetLocaleT()->locinfo->mb_cur_max);
        return 0;
    }
    else {
        /* single byte char */
        if ( MultiByteToWideChar(
               _loc_update.GetLocaleT()->locinfo->lc_codepage,
               MB_PRECOMPOSED | MB_ERR_INVALID_CHARS,
               s,
               1,
               dst,
               (dst != NULL ? 1 : 0)) == 0 )
        {
            errno = EILSEQ;
            _ASSIGN_IF_NOT_NULL(dst, 0);
            _ASSIGN_IF_NOT_NULL(pRetValue, -1);
            return errno;
        }

        _ASSIGN_IF_NOT_NULL(pRetValue, sizeof(char));
        return 0;
    }
}


/***
*wint_t btowc(c) - translate single byte to wide char
*
*Purpose:
*
*Entry:
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/

extern "C" wint_t __cdecl btowc (
    int c
)
{
    if (c == EOF)
    {
        return WEOF;
    }
    else
    {
        /* convert as one-byte string */
        char ch = (char)c;
        mbstate_t mbst = 0;
        wchar_t wc = 0;
        int retValue = -1;

        _mbrtowc_s_l(&retValue, &wc, &ch, 1, &mbst, NULL);
        return (retValue < 0 ? WEOF : wc);
    }
}


/***
*size_t mbrlen(s, n, pst) - determine next multibyte code, restartably
*
*Purpose:
*
*Entry:
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/

extern "C" size_t __cdecl mbrlen (
    const char *s,
    size_t n,
    mbstate_t *pst
)
{
    static mbstate_t mbst = {0};
    int retValue = -1;

    _mbrtowc_s_l(&retValue, NULL, s, n, (pst != NULL ? pst : &mbst), NULL);
    return retValue;
}


/***
*size_t mbrtowc(pwc, s, n, pst) - translate multibyte to wchar_t, restartably
*
*Purpose:
*
*Entry:
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/

extern "C" size_t __cdecl mbrtowc (
    wchar_t *dst,
    const char *s,
    size_t n,
    mbstate_t *pst
)
{
    static mbstate_t mbst = {0};
    int retValue = -1;

    if (s != NULL)
    {
        _mbrtowc_s_l(&retValue, dst, s, n, (pst != NULL ? pst : &mbst), NULL);
    }
    else
    {
        _mbrtowc_s_l(&retValue, NULL, "", 1, (pst != NULL ? pst : &mbst), NULL);
    }
    return retValue;
}


/***
*size_t mbsrtowcs(wcs, ps, n, pst) - translate multibyte string to wide,
*       restartably
*
*Purpose:
*
*Entry:
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/

/* Helper function shared by the secure and non-secure versions. */

extern "C" size_t __cdecl _mbsrtowcs_helper (
    wchar_t *wcs,
    const char **ps,
    size_t n,
    mbstate_t *pst
)
{
    /* validation section */
    _VALIDATE_RETURN(ps != NULL, EINVAL, (size_t)-1);

    static mbstate_t mbst = {0};
    const char *s = *ps;
    int i = 0;
    size_t nwc = 0;
    _LocaleUpdate _loc_update(NULL);

    if (pst == NULL)
    {
        pst = &mbst;
    }

    if (wcs == NULL)
    {
        for (; ; ++nwc, s += i)
        {
            /* translate but don't store */
            wchar_t wc;
            _mbrtowc_s_l(&i, &wc, s, INT_MAX, pst, _loc_update.GetLocaleT());
            if (i < 0)
            {
                return (size_t)-1;
            }
            else if (i == 0)
            {
                return nwc;
            }
        }
    }

    for (; 0 < n; ++nwc, s += i, ++wcs, --n)
    {
        /* translate and store */
        _mbrtowc_s_l(&i, wcs, s, INT_MAX, pst, _loc_update.GetLocaleT());
        if (i < 0)
        {
            /* encountered invalid sequence */
            nwc = (size_t)-1;
            break;
        }
        else if (i == 0)
        {
            /* encountered terminating null */
            s = 0;
            break;
        }
    }

    *ps = s;
    return nwc;
}

extern "C" size_t __cdecl mbsrtowcs (
    wchar_t *wcs,
    const char **ps,
    size_t n,
    mbstate_t *pst
)
{
    /* Call a non-deprecated helper to do the work. */

    return _mbsrtowcs_helper(wcs, ps, n, pst);
}


/***
*errno_t mbsrtowcs_s() - Convert multibyte char string to wide char string.
*
*Purpose:
*       Convert a multi-byte char string into the equivalent wide char string,
*       according to the LC_CTYPE category of the current locale.
*       Same as mbstowcs(), but the destination is ensured to be null terminated.
*       If there's not enough space, we return EINVAL.
*
*Entry:
*       size_t *pRetValue = Number of bytes modified including the terminating NULL
*                           This pointer can be NULL.
*       wchar_t *pwcs = pointer to destination wide character string buffer
*       size_t sizeInWords = size of the destination buffer
*       const char **s = pointer to source multibyte character string
*       size_t n = maximum number of wide characters to store (not including the terminating NULL)
*       mbstate_t *pst = pointer to the conversion state
*
*Exit:
*       The error code.
*
*Exceptions:
*       Input parameters are validated. Refer to the validation section of the function.
*
*******************************************************************************/

extern "C" errno_t __cdecl mbsrtowcs_s (
    size_t *pRetValue,
    wchar_t *dst,
    size_t sizeInWords,
    const char **ps,
    size_t n,
    mbstate_t *pmbst
)
{
    size_t retsize;

    /* validation section */
    _ASSIGN_IF_NOT_NULL(pRetValue, (size_t)-1);
    _VALIDATE_RETURN_ERRCODE((dst == NULL && sizeInWords == 0) || (dst != NULL && sizeInWords > 0), EINVAL);
    if (dst != NULL)
    {
        _RESET_STRING(dst, sizeInWords);
    }
    _VALIDATE_RETURN_ERRCODE(ps != NULL, EINVAL);

    /* Call a non-deprecated helper to do the work. */

    retsize = _mbsrtowcs_helper(dst, ps, (n > sizeInWords ? sizeInWords : n), pmbst);

    if (retsize == (size_t)-1)
    {
        if (dst != NULL)
        {
            _RESET_STRING(dst, sizeInWords);
        }
        return errno;
    }

    /* count the null terminator */
    retsize++;

    if (dst != NULL)
    {
        /* return error if the string does not fit */
        if (retsize > sizeInWords)
        {
            _RESET_STRING(dst, sizeInWords);
            _VALIDATE_RETURN_ERRCODE(sizeInWords <= retsize, ERANGE);
        }
        else
        {
            /* ensure the string is null terminated */
            dst[retsize - 1] = '\0';
        }
    }

    _ASSIGN_IF_NOT_NULL(pRetValue, retsize);

    return 0;
}