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From "Tamas Penzes (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (ZOOKEEPER-2320) C-client crashes when removing watcher asynchronously in "local" mode
Date Sun, 16 Dec 2018 15:02:00 GMT

     [ https://issues.apache.org/jira/browse/ZOOKEEPER-2320?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Tamas Penzes updated ZOOKEEPER-2320:
    Labels: pull-request-available remove_watches  (was: pull-request-available)

> C-client crashes when removing watcher asynchronously in "local" mode
> ---------------------------------------------------------------------
>                 Key: ZOOKEEPER-2320
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2320
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: c client
>    Affects Versions: 3.5.1
>            Reporter: Hadriel Kaplan
>            Assignee: Abraham Fine
>            Priority: Major
>              Labels: pull-request-available, remove_watches
>         Attachments: ZOOKEEPER-2320.patch, ZOOKEEPER-2320.patch
>          Time Spent: 1h 10m
>  Remaining Estimate: 0h
> The C-client library will crash when invoking the asynchronous {{zoo_aremove_watchers()}}
API function with the '{{local}}' argument set to 1.
> The reason is: if the local argument is 1/true, then the code does '{{notify_sync_completion((struct
sync_completion *)data);}}' But casting the '{{data}}' variable to a {{sync_completion}} struct
pointer is bogus/invalid, and when it's later handles as that struct pointer it's accessing
invalid memory.
> As a side note: it will work ok when called _synchronously_ through {{zoo_remove_watchers()}},
because that function creates a {{sync_completion}} struct and passes it to the asynch {{zoo_aremove_watchers()}},
but it will not work ok when the asynch function is used directly for the reason stated perviously.
> Another side note: the docs state that setting the 'local' flag makes the C-client remove
the watcher "even if there is no server connection" - but really it makes the C-client remove
the watcher without notifying the server at *all*, even if the connection to a server is up.
(well... that's what it would do if it didn't just crash instead ;)

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