[jira] [Resolved] (SSHD-424) Avoid inadvertent closure of the input stream used by ScpHelper#receiveFile

["Guillaume Nodet (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SSHD-424?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Guillaume Nodet resolved SSHD-424.
----------------------------------
       Resolution: Fixed
    Fix Version/s: 1.0.0
         Assignee: Guillaume Nodet

https://git-wip-us.apache.org/repos/asf?p=mina-sshd.git;a=commitdiff;h=687e77122cdaf57d4c19a248e2d97a87f0ce6294

> Avoid inadvertent closure of the input stream used by ScpHelper#receiveFile
> ---------------------------------------------------------------------------
>
>                 Key: SSHD-424
>                 URL: https://issues.apache.org/jira/browse/SSHD-424
>             Project: MINA SSHD
>          Issue Type: Bug
>    Affects Versions: 1.0.0, 0.14.0
>            Reporter: Goldstein Lyor
>            Assignee: Guillaume Nodet
>            Priority: Minor
>             Fix For: 1.0.0
>
>         Attachments: 0027-SSHD-424-Avoid-inadvertent-closure-of-the-input-stre.patch
>
>
> The current code wraps the session _InputStream_ inside a _FilterInputStream_ in order to limit the available data for read to the specified length. However, the _FilterInputStream_ instance _close_ method is not overridden - i.e., if the wrapper stream is closed, this will also close the session stream, which would make it impossible to read the ACK (or other SCP commands). Granted, that the current wrapper stream is not inside a _try-with-resource_ block, so *theoretically* it's _close_ method should not be called. However, there are good reasons to (a) override the _close_ method and *explicitly* avoid closing the wrapped stream and (b) place the wrapped stream inside a _try-with-resource_ block:
> * Good programming practices - if a data stream goes out of scope, make sure it is closed.
> * Avoid a possible race condition between the garbage collector and our code. When the garbage collector decides that the wrapper stream is no longer required, it may also decide to close it. However, it may occur while we are trying to read the ACK or be in the midst of processing another SCP command. In such a scenario we would get an _IOException_ on an *unrelated* command.



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