/***
*mbtowc.c - Convert multibyte char to wide char.
*
*       Copyright (c) 1990-1995, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       Convert a multibyte character into the equivalent wide character.
*
*Revision History:
*       03-19-90  KRS   Module created.
*       12-20-90  KRS   Put some intl stuff here for now...
*       03-18-91  KRS   Fixed bogus cast involving wchar_t.  Fix copyright.
*       03-20-91  KRS   Ported from 16-bit tree.
*       07-22-91  KRS   C700 3525: Check for s==0 before calling mblen.
*       07-23-91  KRS   Hard-coded for "C" locale to avoid bogus interim #'s.
*       10-15-91  ETC   Locale support under _INTL (finally!).
*       12-09-91  ETC   Updated nlsapi; added multithread.
*       08-20-92  KRS   Activated NLSAPI support.
*       08-31-92  SRW   Allow INTL definition to be conditional for building ntcrt.lib
*       09-02-92  SRW   Get _INTL definition via ..\crt32.def
*       04-06-93  SKS   Replace _CRTAPI* with _cdecl
*       04-26-93  CFW   Remove unused variable.
*       05-04-93  CFW   Kinder, gentler error handling.
*       06-01-93  CFW   Re-write; verify valid MB char, proper error return,
*                       optimize, fix bugs.
*       06-02-93  SRW   ignore _INTL if _NTSUBSET_ defined.
*       09-15-93  CFW   Use ANSI conformant "__" names.
*       09-28-93  GJF   Merged NT SDK and Cuda versions. Also, replace MTHREAD
*                       with _MT.
*       10-22-93  CFW   Test for invalid MB chars using global preset flag.
*       01-14-94  SRW   if _NTSUBSET_ defined call Rtl functions
*       02-03-94  GJF   Merged in Steve Wood's latest change (affects
*                       _NTSUBSET_ build only).
*       02-07-94  CFW   POSIXify.
*       09-06-94  CFW   Remove _INTL switch.
*       10-18-94  BWT   Fix build warning for call to RtlMultiByteToUnicodeN
*       12-21-94  CFW   Remove invalid MB chars NT 3.1 hack.
*       01-07-95  CFW       Mac merge cleanup.
*       02-06-95  CFW   assert -> _ASSERTE.
*       04-19-95  CFW   Rearrange & fix non-Win32 version.
*       09-26-95  GJF   New locking macro, and scheme, for functions which
*                       reference the locale.
*
*******************************************************************************/

#if defined(  _NTSUBSET_ ) || defined(_POSIX_)
#include <nt.h>
#include <ntrtl.h>
#include <nturtl.h>
#endif
#include <cruntime.h>
#include <stdlib.h>
#include <mtdll.h>
#include <errno.h>
#include <dbgint.h>
#include <ctype.h>
#ifdef _WIN32
#include <internal.h>
#include <locale.h>
#include <setlocal.h>
#endif

/***
*int mbtowc() - Convert multibyte char to wide character.
*
*Purpose:
*       Convert a multi-byte character into the equivalent wide character,
*       according to the LC_CTYPE category of 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  *pwc = pointer to destination wide character
*       const char *s = pointer to multibyte character
*       size_t      n = maximum length of multibyte character to consider
*
*Exit:
*       If s = NULL, returns 0, indicating we only use state-independent
*       character encodings.
*       If s != NULL, returns:  0 (if *s = null char)
*                               -1 (if the next n or fewer bytes not valid mbc)
*                               number of bytes comprising converted mbc
*
*Exceptions:
*
*******************************************************************************/

#if     defined(_MT) && !defined(DLL_FOR_WIN32S)
int __cdecl mbtowc(
        wchar_t  *pwc,
        const char *s,
        size_t n
        )
{
        int retval;
        int local_lock_flag;

        _lock_locale( local_lock_flag )
        retval = _mbtowc_lk(pwc, s, n);
        _unlock_locale( local_lock_flag )
        return retval;
}
#endif  /* _MT */

#if     defined(_MT) && !defined(DLL_FOR_WIN32S)
int __cdecl _mbtowc_lk
#else
int __cdecl mbtowc
#endif
        (
        wchar_t  *pwc,
        const char *s,
        size_t n
        )
{
        _ASSERTE (MB_CUR_MAX == 1 || MB_CUR_MAX == 2);

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

        if ( !*s )
        {
            /* handle NULL char */
            if (pwc)
                *pwc = 0;
            return 0;
        }

#ifdef _WIN32
#if !defined( _NTSUBSET_ ) && !defined (_POSIX_)

        if ( __lc_handle[LC_CTYPE] == _CLOCALEHANDLE )
        {
            if (pwc)
                *pwc = (wchar_t)(unsigned char)*s;
            return sizeof(char);
        }

        if ( isleadbyte((unsigned char)*s) )
        {
            /* multi-byte char */

            if ( MB_CUR_MAX <= 1 || (int)n < MB_CUR_MAX ||
                (MultiByteToWideChar(__lc_codepage, MB_PRECOMPOSED|MB_ERR_INVALID_CHARS,
                s, MB_CUR_MAX, pwc, (pwc) ? 1 : 0) == 0) )
            {
                /* validate high byte of mbcs char */
                if ((n<(size_t)MB_CUR_MAX) || (!*(s+1)))
                {
                    errno = EILSEQ;
                    return -1;
                }
            }
            return MB_CUR_MAX;
        }
        else {
            /* single byte char */

            if ( MultiByteToWideChar(__lc_codepage, MB_PRECOMPOSED|MB_ERR_INVALID_CHARS,
            s, 1, pwc, (pwc) ? 1 : 0) == 0 )
            {
                errno = EILSEQ;
                return -1;
            }
            return sizeof(char);
        }

#else /* _NTSUBSET_ */

        {
            NTSTATUS Status;
            int size;

            Status = RtlMultiByteToUnicodeN(pwc,
                                            (pwc) ? sizeof( *pwc ) : 0,
                                            (PULONG)&size,
                                            (char *) s,
                                            n);
            if (!NT_SUCCESS(Status)) {
                errno = EILSEQ;
                size = -1;
            } else
                size = mblen(s, n);

            return size;
        }

#endif /* _NTSUBSET_/_POSIX_ */
#else /* _WIN32 */

        /* stuck the "C" locale again */
        if (pwc)
            *pwc = (wchar_t)(unsigned char)*s;
        return sizeof(char);

#endif /* _WIN32 */
}