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From: Ken Brown <kbrown@cornell.edu>
To: Daniel Colascione <dancol@dancol.org>, Eli Zaretskii <eliz@gnu.org>
Cc: 17510@debbugs.gnu.org, dmantipov@yandex.ru
Subject: bug#17510: 24.3.91; Problem with `emacs --daemon' in cygw32 build
Date: Sat, 24 May 2014 18:18:47 -0400	[thread overview]
Message-ID: <53811AC7.7060809@cornell.edu> (raw)
In-Reply-To: <5380F2FA.1080007@dancol.org>

On 5/24/2014 3:28 PM, Daniel Colascione wrote:
> On 05/24/2014 05:38 AM, Ken Brown wrote:
>> On 5/19/2014 3:25 PM, Ken Brown wrote:
>>> On 5/19/2014 12:46 PM, Eli Zaretskii wrote:
>>>> I guess it's OK for the branch, thanks.  But it strikes me that simply
>>>> replacing the car of dpyinfo->name_list_element by something like
>>>> "!!!DELETED DISPLAY!!!", or even just an empty string, would serve the
>>>> same purpose, and save us the nuisance of an additional list in
>>>> cygw32_display_name_list.  After all, all you need is to mark a
>>>> display deleted without actually deleting it, right?  IOW, the main
>>>> problem is in x_delete_display, and all the rest is just the overhead
>>>> you needed to fix that, correct?
>>>
>>> I think that's correct, and I agree that there should be a much simpler
>>> fix.  I'll have to look into the code and try to understand better
>>> exactly what happens when emacs is started as a daemon and then a client
>>> frame is opened and closed.
>>
>> My guess as to the cause of this bug was completely wrong.  What happens
>> in my recipe is that the pointer dpyinfo->w32_id_name is freed twice.
>> (This is done in x_delete_display each time the only existing client
>> frame is deleted.)  An attempt to create a client frame for the third
>> time then leads to a crash because of malloc corruption.
>
> Thanks for finding that. I wonder whether this double-free also has
> something to do with random crashes people have been seeing in 64-bit
> Cygwin cygw32 Emacs builds.

I doubt it, because this double-free occurs in both 64-bit and 32-bit 
Cygwin.  Also, I think it can only be triggered by running emacs as a 
daemon, and none of the people reporting crashes mentioned doing that.

Ken






      reply	other threads:[~2014-05-24 22:18 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-16 17:50 bug#17510: 24.3.91; Problem with `emacs --daemon' in cygw32 build Ken Brown
2014-05-16 20:06 ` Ken Brown
2014-05-17 23:39   ` Ken Brown
2014-05-18  4:32     ` Eli Zaretskii
2014-05-18 14:30       ` Ken Brown
2014-05-18 15:11         ` Eli Zaretskii
2014-05-18 19:36           ` Ken Brown
2014-05-19 12:03             ` Ken Brown
2014-05-19 16:46             ` Eli Zaretskii
2014-05-19 17:31               ` Eli Zaretskii
2014-05-19 19:25               ` Ken Brown
2014-05-24 12:38                 ` Ken Brown
2014-05-24 12:59                   ` Eli Zaretskii
2014-05-24 18:14                     ` Ken Brown
2014-05-24 22:18                       ` Ken Brown
2014-05-24 19:28                   ` Daniel Colascione
2014-05-24 22:18                     ` Ken Brown [this message]

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