Re: [Patch]: NUL and other special names

[David Fritz <zeroxdf at att dot net>]

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?
> >
> > Chris,
> >
> > Yes, we have done a "GetFileAttributes". I just checked the values. 
> > For AUX, CON, COMx, LPTx, NUL and PRN, the attribute is 0x20,
> > FILE_ATTRIBUTE_ARCHIVE 
> > 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() ??