Backtrace io_add(0x1) called twice fd= (was Exit status code 134; what is it, in the context of Dovecot Antispam plug-in?)

[Ben Johnson]

On 8/8/2014 4:38 AM, Steffen Kaiser wrote:
> On Thu, 7 Aug 2014, Ben Johnson wrote:
>> On 8/7/2014 11:14 AM, Steffen Kaiser wrote:
>>> one idea: http://www.tldp.org/LDP/abs/html/exitcodes.html
>>> 
>>> exit code 134 would be in bash's meaning (if this website is 
>>> correct all) some program died off signal 6. This would be
>>> Abort in Linux.
>>> 
>>> prepend your script with
>>> 
>>> exec >> /tmp/trace 2>&1 set -vx
>>> 
>>> that will dump anything visible into /tmp/trace
>>> 
>>> - -- Steffen Kaiser
> 
>> Thank you for your continued assistance, Steffen.
> 
>> You seem to be exactly correct with the Abort signal.
> 
>> I prepended the values you suggested to the pipe script and
>> here's the relevant output:
> 
>> + /usr/lib/dovecot/deliver -d sa-training at example.com -m
>> Training.SPAM ^A^H5584 prefix=lda: ^A^F5584 io_add(0x1) called
>> twice fd=7, callback=0x7f23489fb6f0 -> 0x7f23489aa530
> 
> Unfortunately the only spot found is: 
> http://dovecot.org/pipermail/dovecot/2012-May/135636.html
> 
> Is it the same fd=# always? Is it already open in your script? You
> could check with lsof -p $$
> 
> However, you should check if Dovecot v2.2.13 already fixes the
> problem.
> 
> -- Steffen Kaiser

So, I upgraded to Dovecot 2.2.13, and had to build the antispam plugin
from source (because my distro doesn't provide pre-built binary
packages for antispam that meet the dependency requirements for the
Dovecot 2.2.13 packages that reside at http://xi.rename-it.nl/debian/).

The "make" script complained that "dovecot-config" could not be found.
Well, from what I can determine, there is no file by this name in
/usr/lib/dovecot/; the file name appears to be "config" (not
"dovecot-config"). I created a symlink for the name that antispam was
expecting and the build process succeeded. Not sure if there was a
better way to deal with that, but it seemed to work, and everything
seems to be up-and-running at this point.

Also, unless I'm mistaken, the "pipe" back-end for antispam has
disappeared; I'm using mailtrain instead, which seems to work the same
way.

Unfortunately, despite the valiant effort, the behavior is exactly the
same; still seeing exit code status 134 whenever the antispam plugin
fires. :(

And yes, Steffen, the fd=7 is always present and the same.

> Dovecot tries to be admin-friendly. Common error messages are made
> as easily understandable as possible. Any crash, no matter how it
> happened, is considered a bug that will be fixed.

Have we reached this point yet?

Happy to try any other suggestions...

Thanks!

-Ben