mbsncpy.c

C标准库源代码

/***
*mbsncpy.c - Copy one string to another, n chars only (MBCS)
*
*       Copyright (c) 1985-1997, Microsoft Corporation.  All rights reserved.
*
*Purpose:
*       Copy one string to another, n chars only (MBCS)
*
*******************************************************************************/

#ifdef _MBCS

#include <mtdll.h>
#include <cruntime.h>
#include <string.h>
#include <mbdata.h>
#include <mbctype.h>
#include <mbstring.h>


/***
* _mbsncpy - Copy one string to another, n chars only (MBCS)
*
*Purpose:
*       Copies exactly cnt character from src to dst.  If strlen(src) < cnt, the
*       remaining character are padded with null bytes.  If strlen >= cnt, no
*       terminating null byte is added.  2-byte MBCS characters are handled
*       correctly.
*
*Entry:
*       unsigned char *dst = destination for copy
*       unsigned char *src = source for copy
*       int cnt = number of characters to copy
*
*Exit:
*       returns dst = destination of copy
*
*Exceptions:
*
*******************************************************************************/

unsigned char * __cdecl _mbsncpy(
        unsigned char *dst,
        const unsigned char *src,
        size_t cnt
        )
{

        unsigned char *start = dst;

        if ( _ISNOTMBCP )
            return strncpy(dst, src, cnt);

        _mlock(_MB_CP_LOCK);

        while (cnt) {

                cnt--;
                if (_ISLEADBYTE(*src)) {
                        *dst++ = *src++;
                        if ((*dst++ = *src++) == '\0') {
                                dst[-2] = '\0';
                                break;
                        }
                }

                else
                        if ((*dst++ = *src++) == '\0')
                                break;

        }

        /* pad with nulls as needed */

        while (cnt--)
                *dst++ = '\0';

        _munlock(_MB_CP_LOCK);
        return start;
}

#endif  /* _MBCS */