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Date: Tue, 3 Apr 2001 21:56:27 +0200
From: Marius Gedminas <marius DOT gedminas AT uosis DOT mif DOT vu DOT lt>
To: Cygwin <cygwin AT sourceware DOT cygnus DOT com>
Subject: Re: "Lock count exceeded" in mutt
Message-ID: <20010403215627.A8718@gintaras>
Mail-Followup-To: Cygwin <cygwin AT sourceware DOT cygnus DOT com>
References: <3AC9FED1 DOT 8F525542 AT upf DOT es>
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In-Reply-To: <3AC9FED1.8F525542@upf.es>; from wgarcia@upf.es on Tue, Apr 03, 2001 at 06:48:17PM +0200

Hi,

On Tue, Apr 03, 2001 at 06:48:17PM +0200, Walter Garcia-Fontes wrote:
> Dear list,
> I'm asking this question because despite the fact that it refers to
> mutt, it has also to do with cygwin (file permissions on the file
> structure, for programs picky with permissions such as all mail
> programs...)
> 
> Whenever I'm opening mutt I get the message:
> "Lock count exceeded, do you want to remove lock [y,n]?"

Mutt tries to use dotlocking:

      Dotlocking  is  used  on  all kinds of systems.  In order to lock
      an mbox file named folder, an  application first creates a
      temporary file with a unique name in the directory in which the
      folder  resides.  The application then tries to use the link(2)
      system call to create a hard link named folder.lock to the
      temporary  file.   The  success of the link(2) system call should
      be additionally  verified  using stat(2) calls.  If the link has
      succeeded, the mail folder is considered dotlocked.  The temporary
      file can then safely be unlinked.

      In  order  to release the lock, an application just unlinks the
      folder.lock file.

              -- mbox(5)

/var/spool/mail is usually group-writable, and mutt_dotlock is sgid to
group `mail', so it can create the necessary files.  However suid/sgid
executables do not work on CygWin, so /var/spool/mail needs to be
writable by you.

This problem also occurs when the mailbox is on a FAT partition (even on
Linux) -- hard links are not supported there.

Currently I am using Mutt with a spool file in ~/Mail/ (on NTFS
partition) and have no problems with that.  Well, except the fact that
./configure from maildrop aborts since it cannot find a system-wide mail
spool.  But I digress.

Perhaps Mutt CygWin package should be compiled without dotlocking by
default (#undef USE_DOTLOCK in config.h)?  Mutt also uses flock/fcntl to
do locking, shouldn't that be enough?  And there are also native Windows
mandatory locks.

Or maybe use --with-homespool instead?  But that will not solve the
problem with FAT partitions.

See mbox.man that comes with Mutt for details about locking methods.
I'm not sure if this file is available in CygWin's mutt package; I'm
looking at the one from CVS now.  But I think I've seen that description
earlier, in some other file from Mutt docs.

Marius Gedminas
-- 
"I'll be Bach."  -- Johann Sebastian Schwarzenegger

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