On Fri, Aug 22, 2008 at 3:32 AM, Matt Wozniski wrote:
> Not sure what's going on here, but I've found a crash that's easy to
> reproduce. First, open two X11 enabled vim (not gvim) processes. In
> the first, do:
> :let @+ = repeat('a', 1024*1024)
> in order to store 1MB of data to the clipboard. The exact amount is
> irrelevant, but the larger the size, the more often it will lead to a
> segfault.
>
> Then, in the second vim instance, repeatedly do ":reg +" and see what
> gets displayed. Depending upon the amount of data that you put on the
> clipboard, as well as upon some other factor I'm not seeing, this will
> either a) show a bunch of a's in register +, b) not show any
> registers, as though register + didn't exist, or c) cause the vim in
> which you copied to segfault, and the vim in which you're trying to
> display the register to enter a tight loop wasting a lot of CPU and
> only dying for kill -9. Just try the command 5 or so times and you
> should see a segfault - as well as the missing-register behavior. If
> you don't get the segfault at all, try upping the amount of data
> stored to the clipboard. If you get the segfault, but not the
> missing-register behavior, try lowering the amount of data stored to
> the clipboard. And if you can't reproduce either, that might help to
> pin down what exactly causes this.
>
> I can reproduce this on both a vim linked with the GTK2-Gnome gui, and
> one linked with the X11-Motif gui, so it doesn't seem to be something
> gnome-specific, either. This is vim 7.2.
>
> Let me know if we need more details.
>
> ~Matt
It does not seem easy to debug. I think there might
be 2 distinct issues.
1/ The first thing I notice and which seems to be 100% reproducible
on my machine):
In #1 instance of vim: :let @+ = repeat('a', 262033)
In #2 instance of vim: :reg+ (works fine all the time)
In #1 instance of vim: :let @+ = repeat('b', 262034)
In #2 instance of vim: :reg+ (fails all the time, it shows empty content)
clip_x11_request_selection_cb() fails in #2 instance of vim
because parameter value is NULL and parameter *length is null.
Somehow it happens when number of characters in clipboard
is >= 262034 (close to 256K).
I change the letter ('a' -> 'b') in the clipboard every time to make
sure ":reg +" does not show an old value of the clipboard (which
I have observed sometimes, see below)
2/ The second thing I notice, if I put far more characters in the
clipboard (say 1000000) then if fails differently:
In #1 instance of vim: :let @+ = repeat('c', 1000*1000)
In #2 instance of vim: :reg+ (fails, it shows some incorrect
content, something which I happened copy earlier "33333...."?!)
So with such a big clipboard content, it fails differently:
In instance #2 of vim, function clip_x11_request_selection()
retries 5 times until it falls back to calling clip_yank_selection(),
but somehow that does not work either.
If both instances are gvim rather than vim, then I do not see
any problem.
I have not been able to come up with a fix yet.
-- Dominique
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