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Re: Fwd: findutils bug

From: Eric Blake
Subject: Re: Fwd: findutils bug
Date: Mon, 03 Apr 2006 06:23:56 -0600
User-agent: Thunderbird 1.5 (Windows/20051201)

Hash: SHA1

According to James Youngman on 4/3/2006 3:14 AM:
> Notice that the value of st_ino is different between the two calls to
> fstat().   This is triggering the logic within find that detects
> attempted race condition exploits (for example deleting a subdirectory
> and changing it to a symlink to something else).

Indeed, my original guess that this is a cygwin issue is correct.  Ross,
the best thing for you to do is to help the cygwin developers fix access
to remote samba drives.  For example, see this thread:

There, Corinna, one of the primary cygwin developers, acknowledges the
problems in cygwin in interacting with various Samba versions, and even
asks for two pieces of information - the output of 'cygcheck -svr', and
the output of a program at
http://sourceware.org/ml/cygwin/2006-01/msg00818.html that helps her
distinguish what to look for to detect the various Samba versions and
capabilities.  But neither of those outputs are helpful on this list; send
them to the cygwin list.

Also, realize that Samba support is still being improved in cygwin.  This
patch, on Mar 31, http://cygwin.com/ml/cygwin-cvs/2006-q1/msg00279.html,
deals with differentiating between broken versions of samba (pre-3.0.22)
and fixed versions, so that the changing inode problem can be avoided by
faking inodes when dealing with broken versions of samba.  You reported
using a cygwin snapshot; however, the most recent snapshot at that time
was from Mar 29, two days before this patch.  You need to wait for a newer

Cygwin 1.5.18 and prior always faked inodes of remote drives (using a hash
of the filename, rather than anything that Samba reported), with the
result that you cannot do hard links on those drives.  But new enough
samba can support hard links, even from Windows, so 1.5.19 turned on the
use of the inodes reported by samba.  However, since older versions of
Samba put garbage in that field, the inode changes on every read of the
device, leading to the (correct) behavior of find refusing to traverse
that pathname.

Again, without your help, this cygwin bug will not be fixed for 1.5.20.
And complaining to the bug-findutils list is not the right approach -
James does not have access to cygwin, and I don't have access to Samba.  I
am, however, the cygwin volunteer in charge of maintaining the port of the
findutils package, so I follow both lists, and it is pretty obvious to me
which list has the answer to your questions.  Since it is an underlying
bug in how Cygwin handles samba drives, and affects all cygwin programs
(cp is another commonly reported application that suffers when cygwin
1.5.29 uses the buggy samba inodes), your best recourse is to report it to
the cygwin community.

- --
Life is short - so eat dessert first!

Eric Blake             address@hidden
volunteer cygwin findutils package maintainer
Version: GnuPG v1.4.2.1 (Cygwin)
Comment: Public key at home.comcast.net/~ericblake/eblake.gpg
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org


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