rename(2) using NTFS transactions on Vista/2008

Corinna Vinschen corinna-cygwin@cygwin.com
Mon May 19 20:26:00 GMT 2008


On May 19 21:21, Corinna Vinschen wrote:
> On May 19 12:53, Eric Blake wrote:
> > According to Corinna Vinschen on 5/15/2008 12:03 PM:
> >> Hi,
> >> I just applied a patch (rather, three patches) which uses the new
> >> transactional NTFS (TxF) feature introduced with Vista/2008 to add
> >> atomicity in a few border cases of the rename(2) function.  POSIX
> >> requires that rename(2) works atomically, but without the new
> >> transactions, not all cases can be implemented atomically under Windows.
> >
> > cygwin-1.7.0-9 had problems with rename("file","link") returning a spurious 
> > ENOENT.  But I haven't been able to test 1.7.0-10 yet, to see if it has 
> > been fixed.
> 
> Probably not.  How to reproduce?
> 
> > Meanwhile, while looking at the code, is it really a good idea to have 3 
> > stack-allocated path_conv variables, each 32k in size?  That sounds like a 
> 
> They are not necessarily 32K but you're right, they could be in the
> worst case.
> 
> > recipe for disaster if the user's app is nearly at the end of the stack, 
> > and the 32k path_conv straddles the guard page, such that the stack growth 
> > faults outside of the guard page.
> 
> Agreed.  I'll change that to using tmp_pathbufs.

Both problems should be fixed now.


Thanks for the report,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat



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