Mail Archives: cygwin/2010/09/14/15:02:29
On Sep 14 20:59, Corinna Vinschen wrote:
> On Sep 14 17:39, John Carey wrote:
> > On Sep 14 01:12, Corinna Vinschen wrote:
> > > Hmm, I'm still wondering. In theory we don't have to replace the
> > > directory name. We just have to InterlockedExchange the handle, since
> > > we only need to replace the original handle which does not allow
> > > sharing-for-delete with our own handle which does.
> > >
> > > All other border cases (virtual dir, directory with restricted rights)
> > > can be rightfully handled by setting the Win32 CWD to \\?\PIPE\ again.
> > >
> > > That's at least worth a try, isn't it?
> >
> > Oh, I had thought that you wanted it for long paths
> > and directories with restricted rights, too.
>
> That would be nice, but to me it looks like the Win32 API is just too
> restricted for that, so that it won't make much sense. The native API
> can't make any assumption that it would work in such a scenario.
>
> Most Win32 calls will still not work in a restricted rights CWD, because
> they neglect to set the FILE_OPEN_FOR_BACKUP_INTENT flag. And most Apps
> don't set the FILE_FLAG_BACKUP_SEMANTICS flag incalls to CreateFile.
>
> As for long paths, there's some chance that the internal calls creating
> an absolute path from a relative path fail or crash if the CWD is longer
> than MAX_PATH. What MSDN has to say about the maximum path length of
> relative paths(*) is not very promising, at least. Also, even if
> Vista++ allows to create VistaCwd entries with a longer path, this would
> probably break starting native child processes due to the MAX_PATH
> restriction for the CWD in calls to CreateProcess.
>
> > There's one other issue: the new directory will limit deletion
> > very briefly, until replaced. I don't know if that will bother
> > people as much as the current situation.
>
> True. Implementing a full replacement for SetCurrentDirectory as in
> your PoC is still an option. However, I can't do that anymore since
> I'm tainted by reading your code. If you would contemplate to sign
> a copyright assignment(**), we could create a more thorough solution
> with code scanning and all that in the long run.
>
> In the meantime, I could apply my patch and we can try how well it
> works, hacked as it is.
>
>
> Corinna
>
>
> (*) http://msdn.microsoft.com/en-us/library/aa365247%28VS.85%29.aspx
Sorry, I forgot the URL:
(**) http://cygwin.com/contrib.html, the "Before you get started" section.
Corinna
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Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Project Co-Leader cygwin AT cygwin DOT com
Red Hat
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