[Samba] locks cooperating with a server side process

[Chris Green]

Good day folks,

I'm using Samba 2.2.8a [1] on Slackware 9.1  with 2000/XP clients.

I'm attempting to have a process by which a user drags a file using
Windows Explorer into a share.  On the server side, I have a unix
process that polls the directory for new files and then reads them and
deletes them.

I'm having a problem where I can gain the lock but the process is
still writing to the file.

Python code:
      import fcntl
      # open file in rw so I gain exclusive lock
      f = open("cygwin.tar","r+")
      # if this doesn't raise an IOError, the lock is acquired
      fcntl.lockf(f,fcntl.LOCK_EX|fcntl.LOCK_NB)

which maps into a fcntl exclusive lock with 0 as the start,
end, and whence arguments in the flock structure.

In smb.conf, "locking = yes" had no effect on my process.  The next
thing I tried was "strict locking = yes".  This had the effect that
as soon as my code performs the lock, a windows dialog appears:

   ``Cannot copy cygwin: The process cannot access the file because
   another process has locked a portion of the file''

This leads me to suspect that either Windows Explorer or samba doesn't
gain a lock on the file on creation.  Is there a way to tell samba to
set that lock?

Thanks,
Chris

Footnotes: 
[1]  Samba is compiled:
 --with-fhs \
  --prefix=/usr \
  --localstatedir=/var \
  --bindir=/usr/bin \
  --sbindir=/usr/sbin \
  --with-lockdir=/var/cache/samba \
  --sysconfdir=/etc \
  --with-configdir=/etc/samba \
  --with-privatedir=/etc/samba/private \
  --with-codepagedir=/etc/codepages \
  --with-smbmount \
  --with-quotas \
  --with-syslog \
  --with-utmp \
  --with-sambabook=/usr/share/swat/using_samba \
  --with-ssl \
  --with-sslinc=/usr/include/openssl \
  --with-ssllib=/usr \
  --with-msdfs \
  --with-vfs \
  --with-libsmbclient \
  i386-slackware-linux
-- 
Chris Green <cmg at dok.org>
To err is human, to moo bovine.