mbslen_s.cpp

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/***
*mbslen_s.c - Find length of MBCS string
*
*       Copyright (c) Microsoft Corporation.  All rights reserved.
*
*Purpose:
*       Find length of MBCS string
*
*******************************************************************************/
#ifndef _MBCS
    #error This file should only be compiled with _MBCS defined
#endif
 
#include <corecrt_internal.h>
#include <corecrt_internal_mbstring.h>
#include <locale.h>
#include <string.h>
 
/***
* _mbsnlen - Find length of MBCS string
*
*Purpose:
*       Find the length of the MBCS string (in characters).
*
*Entry:
*       unsigned char *s = string
*       size_t maxsize
*
*Exit:
*       Returns the number of MBCS chars in the string.
*       Only the first sizeInBytes bytes of the string are inspected: if the null
*       terminator is not found, sizeInBytes is returned.
*       If the string is null terminated in sizeInBytes bytes, the return value
*       will always be less than sizeInBytes.
*       Returns (size_t)-1 if something went wrong.
*
*Exceptions:
*       Input parameters are validated. Refer to the validation section of the function.
*
*******************************************************************************/
 
size_t __cdecl _mbsnlen_l(
        const unsigned char *s,
        size_t sizeInBytes,
        _locale_t plocinfo
        )
{
        size_t n, size;
        _LocaleUpdate _loc_update(plocinfo);
 
        if (_loc_update.GetLocaleT()->mbcinfo->ismbcodepage == 0)
            return strnlen((const char *)s, sizeInBytes);
 
        /* Note that we do not check if s == nullptr, because we do not
         * return errno_t...
         */
 
        /* Note that sizeInBytes here is the number of bytes, not mb characters! */
        for (n = 0, size = 0; size < sizeInBytes && *s; n++, s++, size++)
        {
            if ( _ismbblead_l(*s, _loc_update.GetLocaleT()) )
                        {
                                size++;
                                if (size >= sizeInBytes)
                                {
                                        break;
                                }
                if (*++s == '\0')
                                {
                    break;
                                }
            }
        }
 
                return (size >= sizeInBytes ? sizeInBytes : n);
}
 
size_t __cdecl _mbsnlen(
        const unsigned char *s,
        size_t maxsize
        )
{
    return _mbsnlen_l(s,maxsize, nullptr);
}