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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (ZOOKEEPER-2891) SIGABRT from assert during fake completion on zookeeper_close.
Date Thu, 07 Feb 2019 10:40:00 GMT

     [ https://issues.apache.org/jira/browse/ZOOKEEPER-2891?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

ASF GitHub Bot updated ZOOKEEPER-2891:
--------------------------------------
    Labels: easyfix pull-request-available  (was: easyfix)

> SIGABRT from assert during fake completion on zookeeper_close.
> --------------------------------------------------------------
>
>                 Key: ZOOKEEPER-2891
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2891
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: c client
>    Affects Versions: 3.4.10
>         Environment: Linux ubuntu 4.4.0-87-generic
> gcc (Ubuntu 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609
> https://github.com/apache/zookeeper.git
> branch-3.4
>            Reporter: Alexander A. Strelets
>            Assignee: Alexander A. Strelets
>            Priority: Critical
>              Labels: easyfix, pull-request-available
>             Fix For: 3.4.10
>
>
> ZooKeeper C Client *+single thread+* build
> Function *_deserialize_multi()_* hits *_assert(entry)_* when called for the so called
"Fake response" which is fabricated by the function _free_completions()_ for example when
_zookeeper_close()_ is called while there is a pending _multi_ request.
> Such fake response includes only the header but zero bytes for the body. Due to this
{{deserialize_MultiHeader(ia, "multiheader", &mhdr)}}, which is called repeatedly for
each {{completion_list_t *entry = dequeue_completion(clist)}}, does not assign the _mhdr_
and keeps _mhdr.done == 0_ as it was originally initialized. Consequently the _while (!mhdr.done)_
does not ever end, and finally falls into the _assert(entry)_ with _entry == NULL_ when all
sub-requests are "completed". ~// Normally on my platform assert raises SIGABRT.~
> I propose to instruct the _deserialize_multi()_ function to break the loop on _entry
== NULL_ if it was called for an unsuccessfull overal status of the multi response, and in
particular for the fake response having _ZCLOSING_ (-116) status. I have introduced the _rc0_
parameter for this.
> *Another issue* with this function is that even if the while-loop exited properly, this
function returns _rc == 0_, and this return code +overrides+ the true status value with {{rc
= deserialize_multi(xid, cptr, ia, rc)}} in the _deserialize_response()_ function. So, the
_multi_ response callback +handler would be called with _rc == ZOK_ instead of _rc == ZCLOSING_+
which is strictly wrong.
> To fix this I propose initializing _rc_ with the introduced _rc0_ instead of zero (which
is _ZOK_ indeed).
> This is a proposed fix: https://github.com/apache/zookeeper/pull/360
> [upd]
> It looks like about the same problem is described in ZOOKEEPER-1636
> However, the patch proposed in this ticket also remedies the second linked problem: reporting
ZCLOSING status (as required) to the multi-request completion handler.



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