[jira] [Updated] (NET-427) In certain error/failure circumstances ftpClient.listFiles(param) returns an empty list instead of null or an exception

["Mario Zannone (Updated) (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/NET-427?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mario Zannone updated NET-427:
------------------------------

    Attachment: log_excerpt.txt
                FtpTest.java

Test program and log excerpt
                
> In certain error/failure circumstances ftpClient.listFiles(param) returns an empty list instead of null or an exception
> -----------------------------------------------------------------------------------------------------------------------
>
>                 Key: NET-427
>                 URL: https://issues.apache.org/jira/browse/NET-427
>             Project: Commons Net
>          Issue Type: Bug
>          Components: FTP
>    Affects Versions: 3.0.1
>         Environment: SunOS 5.10 Generic_144489-06
>            Reporter: Mario Zannone
>            Priority: Minor
>         Attachments: FtpTest.java, log_excerpt.txt
>
>
> According to the API docs ftpClient.listFiles(String) should return
> null or an exception on error conditions or failure:
>  The convention for all the FTP command methods in FTPClient is
>  such that they either return a boolean value or some other value.
>  The boolean methods return true on a successful completion reply
>  from the FTP server and false on a reply resulting in an error
>  condition or failure. The methods returning a value other than
>  boolean return a value containing the higher level data produced
>  by the FTP command, or null if a reply resulted in an error
>  condition or failure.
> ( http://commons.apache.org/net/apidocs/org/apache/commons/net/ftp/FTPClient.html )
> However in certain error/failure circumstances listFiles(param)
> returns an empty list instead of null.
> Note that an empty list is a correct response when param does not
> match any file.
> We were able to bypass the problem checking the ftp reply with
> getReplyCode().  However, this listFiles behaviour is unexpected 
> and should at least be documented.
> The error is not systematic and not easy to diagnose or replicate.
> We were able to reproduce it using cron to run the attached
> program every minute on a slow and unreliable connection;
> in 24h the error did show only a couple of times.
> Attachments: test program and excerpt from the test log.

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