GNU bug report logs - #70415
30.0.50; [Cygwin] `lock-file' creates a symlink with funny name

Previous Next

Full log

View this message in rfc822 format

From: Ken Brown <kbrown <at> cornell.edu>
To: Eli Zaretskii <eliz <at> gnu.org>, Katsumi Yamaoka <yamaoka <at> jpl.org>
Cc: 70415 <at> debbugs.gnu.org
Subject: bug#70415: 30.0.50; [Cygwin] `lock-file' creates a symlink with funny name
Date: Mon, 22 Apr 2024 12:15:42 -0400

On 4/17/2024 8:21 AM, Eli Zaretskii wrote:
>> Date: Wed, 17 Apr 2024 08:58:42 +0900
>> From: Katsumi Yamaoka <yamaoka <at> jpl.org>
>> Cc: 70415 <at> debbugs.gnu.org
>>
>> On Tue, 16 Apr 2024 16:32:17 +0300, Eli Zaretskii wrote:
>>>> .#FILE -> username <at> hostname.1234:-11644473599
>>>> For that case `(unlock-file "FILE")' issues this warning:
>>>> Warning (unlock-file): Unlocking file: Invalid argument, FILE, ignored
>>
>>> The part after the colon is the system boot time, and is used on all
>>> Posix hosts.
>>
>> Oh, I had never seen it until recently.  Thanks.
> 
> The question is: why it started appearing only recently?  The code in
> filelock.c hasn't changed since last December, if not earlier, so if
> this started happening recently, it could only be because Gnulib's
> get_boot_time or its Cygwin implementation changed, such that it was
> previously returning zero whereas now it returns non-zero (which
> triggers the addition of the ":BOOT_TIME" part to the file name).
> 
>>>> | commit 393f58c85aeb78f814866ccaad9ae7efd3fa6766
>>>> | Author: Adam Porter <adam <at> alphapapa.net>
>>>> | Date:   Fri Mar 8 23:43:14 2024 -0600
>>
>>> This is extremely unlikely to have caused the problem.  It is more
>>> likely that some change in Cygwin and/or in the Gnulib's boot-time
>>> module causes this now.
>>
>> Indeed.  But the fact is that Emacs built with that revno adds
>> a colon and a negative number to a link name and the one built
>> with just before it does not.  No problem on 29.3.50 and earlier,
>> either (i.e., not add a colon and numbers).
> 
> Then please step with a debugger through the relevant code in
> filelock.c, before and after that change, and see why they are
> different.  I cannot explain that, even after doing "git log -L" on
> all of filelock.c: the most recent change of the related code was in
> Aug 2023, AFAICT, which is a very far cry from Mar 2024.
> 
> And even if we understand why you now get the ":BOOT_TIME" part,
> there's still the question why it cannot be unlinked, if Cygwin
> supports file names with a colon.  Maybe it's because Emacs creates a
> symlink, and symlinks with such names are not supported by Cygwin?

I'm still traveling for another week and won't have time to try to 
reproduce and debug this until I return.  But I did do one quick test in 
a Cygwin shell.  I created a symlink

  .#FILE -> username <at> hostname.1234:-11644473599

and deleted it with rm.  So symlinks like this are indeed supported by 
Cygwin.

To be continued...

Ken

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.