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() ??