msvc-strncpy.h

// C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\atlmfc\include\atlutil.h
inline char * __cdecl _strncpy(
	_Out_writes_z_(count) char * dest,
	_In_reads_z_(count) const char * source,
	_In_ size_t count) throw()
{
	ATLASSERT( dest != NULL );
	ATLASSERT( source != NULL );
	if(!dest || count==0)
	{
		return NULL;
	}
	if(dest!=source)
	{
		dest[0]='\0';
	}
	if(!source && count>0)
	{
		return NULL;
	}

	char *start = dest;

	while (count && (*dest++ = *source++))
	{
		count--;
	}

	return(start);
}

inline bool _SafeStringCopy(
	_Out_writes_z_(nLen) char *szDest,
	_In_reads_z_(nLen) const char *szSrc,
	_In_ size_t nLen) throw()
{
	ATLASSERT( szDest != NULL );
	ATLASSERT( szSrc != NULL );

	// initialize for check below
	szDest[nLen-1] = '\0';

	_strncpy(szDest, szSrc, nLen);
	if ('\0' != szDest[nLen-1])
	{
		// string was too large
		szDest[nLen-1] = '\0';
		return false;
	}
	return true;
}