[NET-225] FTPFileEntryParserImpl.preParse() doesn't remove unparsable entries at the end of the file list

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.4, 2.1
• Fix Version/s: 2.0

Environment

commons-net-1.4.1; Windows XP/2003; JRE 1.5.013-b05; Ant 1.7.0; Embedded FTP server UNIX type L8;

• Assignee: Unassigned
• Reporter: Sergey Shcherbakov
• Created: 02/Jul/08 11:05
• Updated: 04/Jun/11 19:24
• Resolved: 15/Aug/08 19:06

Description

I am using Ant 1.7.0 task to get files from our Embedded FTP server:
<ftp server="${xxxximage.master.test.xxxx.ip}"
port="${xxxximage.master.test.xxxx.port}"
userid="${xxxximage.master.test.xxxx.user}"
password="${xxxximage.master.test.xxxx.password}"
remotedir="${xxxximage.master.test.xxxx.dir}"
retriesAllowed="3"
action="get"
skipFailedTransfers="true"
systemTypeKey="UNIX"
>
<fileset dir="${xxxximage.master.dist.test.nunit.dir}">
<include name="${xxxximage.master.test.xxxx.results}"/>
</fileset>
</ftp>
Ant task crashes with the following error message:
java.lang.NullPointerException
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.jav
a:115)
at org.apache.tools.ant.Task.perform(Task.java:348)
at org.apache.tools.ant.Target.execute(Target.java:357)
at org.apache.tools.ant.Target.performTasks(Target.java:385)
at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1329)
at org.apache.tools.ant.Project.executeTarget(Project.java:1298)
at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExe
cutor.java:41)
at org.apache.tools.ant.Project.executeTargets(Project.java:1181)
at org.apache.tools.ant.Main.runBuild(Main.java:698)
at org.apache.tools.ant.Main.startAnt(Main.java:199)
at org.apache.tools.ant.launch.Launcher.run(Launcher.java:257)
at org.apache.tools.ant.launch.Launcher.main(Launcher.java:104)
Caused by: java.lang.NullPointerException
at org.apache.tools.ant.taskdefs.optional.net.FTP$FTPDirectoryScanner.ch
eckRemoteSensitivity(FTP.java:583)
at org.apache.tools.ant.taskdefs.optional.net.FTP$FTPDirectoryScanner.fo
rceRemoteSensitivityCheck(FTP.java:552)
at org.apache.tools.ant.taskdefs.optional.net.FTP$FTPDirectoryScanner.sc
an(FTP.java:231)
at org.apache.tools.ant.taskdefs.optional.net.FTP.transferFiles(FTP.java
:1570)
at org.apache.tools.ant.taskdefs.optional.net.FTP.transferFiles(FTP.java
:1683)
at org.apache.tools.ant.taskdefs.optional.net.FTP.execute(FTP.java:2373)

at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288)
at sun.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.jav
a:105)
... 11 more
— Nested Exception —
java.lang.NullPointerException
at org.apache.tools.ant.taskdefs.optional.net.FTP$FTPDirectoryScanner.ch
eckRemoteSensitivity(FTP.java:583)
at org.apache.tools.ant.taskdefs.optional.net.FTP$FTPDirectoryScanner.fo
rceRemoteSensitivityCheck(FTP.java:552)
at org.apache.tools.ant.taskdefs.optional.net.FTP$FTPDirectoryScanner.sc
an(FTP.java:231)
at org.apache.tools.ant.taskdefs.optional.net.FTP.transferFiles(FTP.java
:1570)
at org.apache.tools.ant.taskdefs.optional.net.FTP.transferFiles(FTP.java
:1683)
at org.apache.tools.ant.taskdefs.optional.net.FTP.execute(FTP.java:2373)

at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288)
at sun.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.jav
a:105)
at org.apache.tools.ant.Task.perform(Task.java:348)
at org.apache.tools.ant.Target.execute(Target.java:357)
at org.apache.tools.ant.Target.performTasks(Target.java:385)
at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1329)
at org.apache.tools.ant.Project.executeTarget(Project.java:1298)
at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExe
cutor.java:41)
at org.apache.tools.ant.Project.executeTargets(Project.java:1181)
at org.apache.tools.ant.Main.runBuild(Main.java:698)
at org.apache.tools.ant.Main.startAnt(Main.java:199)
at org.apache.tools.ant.launch.Launcher.run(Launcher.java:257)
at org.apache.tools.ant.launch.Launcher.main(Launcher.java:104)

The problem is in the Commons-Net library used internally by the Ant task.
Our FTP server returns empty string at the end of the requested folder file list that causes the org.apache.commons.net.ftp.FtpClient.listFiles() method to return FTPFile array with null elements at the end, which in turn causes NullPointer exception in the org.apache.tools.ant.taskdefs.optional.net.FTP.checkRemoteSensivity() method.

The problem occurs because the org.apache.commons.net.ftp.FTPFileEntryParserImpl.preParse() methods designed to wipe off non-valid lines from the file list response doesn't remove trailing empty lines from response inspite of its Javadoc description: "This default implementation removes entries that do not parse as files."

The issue can be fixed by removing
else {
break;
}
clause from the method's implementation.

I have checked the HEAD version of the FTPFileEntryParserImpl.java file. The else

{ break; }

clause still remains there and I can reproduce issue with the HEAD version of the commons.net.ftp, thus I am assuming that the issue occurs in the commons-net 1.4.1 as well as in the latest development version.