OSGI framework hangs when loading native library

Question

Situation: Open source OSGI framework SMILA (http://www.eclipse.org/smila/) started as Windows Service with the aid of Apache commons-daemon (http://commons.apache.org/daemon/). Trying to load a DLL via System.loadLibrary() from OSGI bundle while Manifest.mf includes Bundle-NativeCode: path/to/dll.

Environment: Windows Server 2003, Java 1.6

Error: During the invocation of System.loadLibrary() the complete Java process hangs. When the service is stopped System.loadLibrary() finish and code execution goes on until the OSGI framework shut down.

The error doesn’t occur on Windows Server 2008 or if the OSGI framework isn’t started as service.

The DLL itself is stripped down to no functionality for testing. All imports are static and the only depended library is kernel32.ddl.

Could anyone imagine why this is happening and how to fix it?

---

Manifest containing DLL:

Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: NTFS Utils Acl Win32 Library
Bundle-SymbolicName: com.eccenca.utils.ntfs.acl.win32
Bundle-Version: 2.2.0
Bundle-Vendor: brox IT-Solutions GmbH
Fragment-Host: com.eccenca.utils.ntfs
Eclipse-PlatformFilter: (& (osgi.os=win32) (osgi.arch=x86))
Bundle-NativeCode: ntfsacl/Release/NtfsAcl.dll
Bundle-RequiredExecutionEnvironment: JavaSE-1.6+

Manifest containing code:

Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: NTFS Utils Acl
Bundle-SymbolicName: com.eccenca.utils.ntfs
Bundle-Version: 2.2.0
Bundle-Vendor: brox IT-Solutions GmbH
Export-Package: com.eccenca.processing.acl,
 com.eccenca.utils.ntfs
Import-Package: org.apache.commons.io;version="1.4.0",
 org.apache.commons.lang,
 org.apache.commons.logging;version="1.1.1",
 org.eclipse.smila.blackboard;version="0.8.0",
 org.eclipse.smila.datamodel,
 org.eclipse.smila.processing;version="0.8.0",
 org.eclipse.smila.processing.pipelets;version="0.8.0",
 org.eclipse.smila.utils.config;version="0.8.0",
 org.eclipse.smila.utils.service;version="0.8.0",
 org.osgi.framework;version="1.4.0"
SMILA-Pipelets: com.eccenca.processing.acl.AccessListConverterPipelet
Bundle-RequiredExecutionEnvironment: JavaSE-1.6

Code snipped with System.loadLibrary() invocation:

public class ACLList {
  private static final org.apache.commons.logging.Log LOG = 
      org.apache.commons.logging.LogFactory.getLog(ACLList.class);

  static {
    try {
      LOG.debug("Start loading library");
      System.loadLibrary("NtfsAcl");
      if (LOG.isInfoEnabled()) {
        LOG.info("NTFS ACL library was succesfully loaded");
      }
    } catch (Throwable e) {
      LOG.error(e);
    }
  }

  private ACLList() {
  }

  public static native ArrayList<ACLEntry> getAccessFor(String path, 
      String serverName) throws IOException;

}

Answer 1

There are two possible issues with the situation you described; I don't know exactly how Equinox handles native code, so I'll just present them to you both.

Bundle-NativeCode requires at least one parameter

You use a Bundle-NativeCode header that just defines a library, and it seems you use Eclipse-PlatformFilter to specify what that library is intended for. Section 3.10 of the spec shows that you need at least one parameter for the library to be selected.

You can change your Bundle-NativeCode header to read

Bundle-NativeCode: ntfsacl/Release/NtfsAcl.dll;osname=win32

and your bundle will be able to find the right library.

Load only from your own bundle

Judging from your code, it could be possible that you define the library in one bundle, and try to load it in another; that doesn't work, a bundle can only load a library that it contains itself.