apangin / class-file-extractor

Extract loaded classes from a running JVM application

Class File Extractor

Extract loaded classes from a running JVM application

Download

• extractor.jar

Usage

java -jar extractor.jar <pid> <output.jar> [prefix]

• <pid> - process ID of the target JVM.
• <output.jar> - output file name (where to store the extracted class files).
• [prefix] - optional class name prefix (e.g. to extract classes only in a selected package).

class-file-extractor's Issues

Invalid Agent jar path on linux

On linux when trying to load the agent we get the following exception:
Exception in thread "main" com.sun.tools.attach.AgentLoadException: Agent JAR not found or no Agent-Class attribute at jdk.attach/sun.tools.attach.HotSpotVirtualMachine.loadAgent(HotSpotVirtualMachine.java:163) at com.extractor.ClassFileExtractor.main(ClassFileExtractor.java:74)

The reason for that is that the jar path is invalid.
The substring call on line 62 get rids 6 characters. This causes the first "/" to not be included in the full path of the agent jar.
We need only get rid of "file:" substring in linux.
Changing this line to following:
String jar = url.substring(5);
solves the issue for me.

Thanks!

P.S. I am using jdk18 if it matters

Exception in thread "main"

Hi! I'm getting this error:

└┌(Downloads)┌¨˙java -jar extractor.jar 36920 test.jar
Exception in thread "main" com.sun.tools.attach.AgentLoadException: 100
	at jdk.attach/sun.tools.attach.HotSpotVirtualMachine.loadAgentLibrary(HotSpotVirtualMachine.java:112)
	at jdk.attach/sun.tools.attach.HotSpotVirtualMachine.loadAgentLibrary(HotSpotVirtualMachine.java:123)
	at jdk.attach/sun.tools.attach.HotSpotVirtualMachine.loadAgent(HotSpotVirtualMachine.java:151)
	at ClassFileExtractor.main(Unknown Source)

The process im trying to extract is Minecraft. Have you any ideas why isn't it working ?
Thanks!

Exception in thread "main" java.lang.NoClassDefFoundError: com/sun/tools/attach/VirtualMachine

$ /jdk1.8.0_151/bin/java -jar extractor.jar 45 mainloader.jar *
Exception in thread "main" java.lang.NoClassDefFoundError: com/sun/tools/attach/VirtualMachine
at ClassFileExtractor.main(Unknown Source)
Caused by: java.lang.ClassNotFoundException: com.sun.tools.attach.VirtualMachine
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 1 more

Library doesn't work method agentmain(String cmdline, Instrumentation inst) is not used.

Library does not do what is supposed to do.

Method agentmain(String cmdline, Instrumentation inst) which is supposed to do main logic is not used anywhere at all.