[Patch]: NUL and other special names

David Fritz zeroxdf@att.net
Wed Jun 2 21:17:00 GMT 2004

Christopher Faylor wrote:
> On Tue, Jun 01, 2004 at 06:11:55PM -0400, Pierre A. Humblet wrote:
>>Christopher Faylor wrote:
>>>On Mon, May 31, 2004 at 06:46:11PM -0400, Pierre A. Humblet wrote:
>>>>This patch prevents NtCreateFile from creating files with special
>>>>names such as NUL.
>>>>Because this needs to be checked very often, I tried to code it
>>>>efficiently with a binary search (it can perhaps be reused elsewhere).
>>>>The new function is_special_name() overlaps with special_name(),
>>>>although there are small differences (it was designed from tests
>>>>on XP Home Ed). Perhaps these two can be merged one day.
>>>Haven't we already done a "GetFileAttributes" on the path by the time
>>>it reaches the NtCreateFile?  If so, couldn't we just avoid trying to
>>>create a file which has "bad" attributes?
>>Yes, we have done a "GetFileAttributes". I just checked the values. 
>>For AUX, CON, COMx, LPTx, NUL and PRN, the attribute is 0x20,
>>For conin$, conout$ and clock$ it is FFFFFFFF
>>So we could filter on those values and only test for special names
>>if necessary.
>>Is that what you meant?
> I was hoping there might be more state available than that.  Oh well.
> Is the GetFileType call any better?
> I keep thinking that there is a layer of translation that we're missing
> here and we should be somehow using an enumeration that the OS provides
> rather than coming up with our own table.
> cgf

NtQueryAttributesFile() ??

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