Regression: FileUtils.copyDirectory(File srcDir, File destDir) fails on Windows

[elharo]

This method worked in 3.1.0 and fails in 3.3.0 as I found by trying to upgrade maven-release from 3.10 to 3.3.0

This bug is shared (likely because of code copied from one place to another) between the similar methods in Apache commons IO, codehaus-plexus-utils, and maven-shared-utils.

I don't have an isolated test case because this bug is platform specific and I've only seen it in Travis CI builds on Windows using JDK 7 through 15. I don't have a Windows box handy to test it. However it is reproducible.

Typical code that triggers it is in RestoreBackupPomsPhaseTest in maven-release:

        // copy poms so tests are valid without clean
        File sourceDir = getTestFile( "src/test/resources" + projectPath );
        File testDir = getTestFile( "target/test-classes" + projectPath );
        FileUtils.copyDirectoryStructure( sourceDir, testDir );

I don't know whether there might be something weird in the setup of those two directories that's involved.

Typical error message is:

Caused by: java.nio.file.FileSystemException:
F:\jenkins\jenkins-slave\workspace\maven-box_maven-release_windows@2@2\windows-jdk8-m3.6.x_build\maven-release-manager\target\test-classes\projects\restore-backup-poms\basic-pom\pom.xml: The process cannot access the file because it is being used by another process

"The process cannot access the file because it is being used by another process" I think points to the root of the bug. This is a Windows file system error message.

Some history is here where I noticed it:

apache/maven-release#42

In this case, I started with plexus-utils 3.1.0 which worked, upgraded t plexus-utils 3.3.0, which didn't. And then tried the FileUtils.copyDirectory from both maven-shared-utils and commons-io, all of which failed in the same way.

I think this is caused by the use of NIO, which doesn't work quite the same when copying files on Windows as on Linux and Mac OS X.

see https://issues.apache.org/jira/browse/IO-663 and https://issues.apache.org/jira/browse/MSHARED-882

[michael-o]

I will a look at this one too.

[gnodet]

Is that still an issue ? maven-release has been recently upgraded to latest plexus-utils apache/maven-release@53d6743

[elharo]

It probably is, though the way it manifests in the Maven test suite has been worked around. It seems to happen when a file is left open, possibly in the source directory. When the test was updated to properly close the file, the problem disappeared. So arguably it is a bug in client code and yet:

1. Only on Windows. Linux can copy open files just fine.
2. Non-NIO based solutions were more robust against open files.