This is the mail archive of the
cygwin-developers
mailing list for the Cygwin project.
Re: 1.7.5: Occasional failure of CreatePipe or signal handing due to thread-unsafe code in cwdstuff::set
On Thu, Aug 12, 2010 at 06:07:27PM +0200, Corinna Vinschen wrote:
>On Aug 12 11:51, Christopher Faylor wrote:
>> On Thu, Aug 12, 2010 at 04:48:48PM +0200, Corinna Vinschen wrote:
>> >On Aug 12 16:38, Corinna Vinschen wrote:
>> >> On Aug 12 10:12, Christopher Faylor wrote:
>> >> > I've done some googling but I can't find an answer to this: Is it
>> >> > possible to create a directory which can't be written to - even by a
>> >> > privileged user?
>> >>
>> >> No. I never came across a directory which is not writable under
>> >> SE_BACKUP_NAME conditions.
>> >
>> >What if we create a subdirectory like C:/cygwin/.for_win32_only
>> >for exactly this one single purpose, to redirect any relative
>> >Win32 calls there?
>>
>> I guess that would be an acceptable compromise if the below doesn't past
>> muster:
>>
>> On XP, at least, we could set the current directory to '//?/PIPE'.
>> That causes CreateFile to fail. I used the program below to test
>> that.
>>
>> sh-3.2$ ./setdir '//?/PIPE'
>> SetCurrentDirectory succeeded
>> CreateFile failed, 123
>>
>> I'll try that on other systems to see if it still behaves predictably.
>
>Works fine on W7 if you specify \\?\PIPE\, with the trailing backslash.
>Without trailing backslash it fails:
>
> $ ./setdir '\\?\PIPE'
> SetCurrentDirectory faile, 123
>
> $ ./setdir '\\?\PIPE\'
> CreateFile failed, 2
>
>That sounds like a neat solution. I would never have expected that
>SetCurrentDirectory works for the pipe FS.
Thanks for testing. As is always the case, I've just found that my
virtual machines have all stopped working so I couldn't quickly test
this myself. I'm rebuilding my kernel now. Then I'll find that a bunch
of other stuff has broken. Then I'll rebuild that. So, sometime
mid-next-week I'll be able to actually try this myself.
Btw, I found this by stepping through the //?/Global??/ namespace
as shown by the sysinternals Winobj utility.
cgf