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Posted to dev@mina.apache.org by "perfah (Jira)" <ji...@apache.org> on 2026/03/20 15:30:00 UTC
[jira] [Commented] (SSHD-1350) NPE when SftpFileSystem is closed (auto-closable)
[ https://issues.apache.org/jira/browse/SSHD-1350?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18067104#comment-18067104 ]
perfah commented on SSHD-1350:
------------------------------
After posting this I realized there has been some recent updates to the library.
If it has already been patched, please let me know fix version.
> NPE when SftpFileSystem is closed (auto-closable)
> -------------------------------------------------
>
> Key: SSHD-1350
> URL: https://issues.apache.org/jira/browse/SSHD-1350
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 2.15.0
> Environment: Win 11 Pro 64
> Reporter: perfah
> Priority: Major
>
> Hi! We are doing a simple:
>
> {code:java}
> try (var children = Files.list(path)) { ... }{code}
>
> And find that an exception is thrown occasionally (see stacktrace below). It appears that an NPE is triggered when the _close()_ method of the auto-closable _SftpFileSystem_ class is called.
> Now according to my client, this exception is only seen in the log when there are a lot of files on the server (e.g. 140 files), whereas all is working smoothly with just a handful. Because the error is thrown repeatedly, our service is malfunctioning in the former scenario.
> I believe this is a bug because of the following principles:
> * Implementations of AutoClosable#close should remain idempotent: if it's already closed, do nothing, don't throw an error the second time, for example.
> * NPEs shouldn't surface to the user of the library.
> * The success of NIO file operations shouldn't be contingent on the number of files on the server.
> Highly appreciate feedback on the matter. Please let me know if you want some more details, or if I am missing something is my analysis.
> --
> java.lang.NullPointerException: Cannot invoke "org.apache.sshd.client.session.ClientSession.getAttribute(org.apache.sshd.common.AttributeRepository$AttributeKey)" because the return value of "org.apache.sshd.sftp.client.fs.SftpFileSystem.getClientSession()" is null
> at org.apache.sshd.sftp.client.fs.SftpFileSystem.close(SftpFileSystem.java:270)
> at org.apache.sshd.sftp.client.fs.SftpDirectoryStream.close(SftpDirectoryStream.java:142)
> ... [CLASSIFIED]
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