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https://issues.apache.org/jira/browse/ZOOKEEPER-2320?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15336662#comment-15336662
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Abraham Fine commented on ZOOKEEPER-2320:
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Hi [~rgs]! I will provide a patch. Thanks for the offer to review.
> 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
>
> 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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