Question: how does the RPC bridge handle class callbacks?

[mahaloz]

Thank you for running such an awesome project! I've recently been looking back into using Python3 in Ghidra in a background process type of way and it seems you've got it handled pretty well with the background processing.

However, I was confused about how you handle something like class callbacks that Ghidra does. For instance, in one of my Java projects I am thinking of porting to Python3, I implement the DomainObjectListener class:
https://github.com/mahaloz/decomp2dbg/blob/69ad8ede239cdb5eab8a776f33426b980277cd2c/decompilers/d2d_ghidra/src/main/java/decomp2dbg/D2DPlugin.java#L49

I do this because it's a special class that will get callbacks from Ghidra whenever a DomainObject changes (like a function name).
It's clear to me that I can do this:

class MyListener(DomainObjectListener):
    pass

But I have no idea how I register this class with Ghidra... i.e., I don't know how to inject this into the Python 2 globals area on Ghidra.

I was curious if you had any advice or tried to do something similar with this project.

Thanks!

[mahaloz]

Ok, I've answered my own question. THIS IS AMAZING! Truly @justfoxing, amazing project. This works:

[ins] In [1]: import ghidra_bridge
         ...: b = ghidra_bridge.GhidraBridge(namespace=globals()) # creates the bridge and loads the fl
         ...: at API into the global namespace
         ...: print(getState().getCurrentAddress().getOffset())
4196125

[ins] In [2]: module = b.remote_import("ghidra.framework.model")

[ins] In [6]: class MyListener(module.DomainObjectListener):
         ...:     def domainObjectChanged(self, ev):
         ...:         print(ev)
         ...: 

[ins] In [7]: l = MyListener()

[ins] In [8]: l
Out[8]: <_bridged___main__.MyListener('org.python.proxies.__main__$MyListener$7@4082bddb', type=__main__.MyListener, handle=93b68807-cf8e-4a3e-9452-76a43a2198a7)>

[ins] In [9]: currentProgram.addListener(l)

ghidra.framework.model.DomainObjectChangedEvent[source=fauxware - .ProgramDB]

That last line you are seeing is a callback being handled after I changed a name in Ghidra. Wow, I'm honestly amazing.

I did however get one crash on the Ghidra side:

AttributeError: 'ghidra.program.database.ProgramDB' object has no attribute '__module__'
Traceback (most recent call last):
  File "/home/mahaloz/ghidra_scripts/jfx_bridge/bridge.py", line 1003, in local_get
    result = getattr(target, name)
AttributeError: 'ghidra.program.database.ProgramDB' object has no attribute '__module__'
Traceback (most recent call last):
  File "/home/mahaloz/ghidra_scripts/jfx_bridge/bridge.py", line 1003, in local_get
    result = getattr(target, name)
AttributeError: 'instancemethod' object has no attribute '_partialmethod'
Traceback (most recent call last):
  File "/home/mahaloz/ghidra_scripts/jfx_bridge/bridge.py", line 1003, in local_get
    result = getattr(target, name)
AttributeError: 'instancemethod' object has no attribute '__code__'
Traceback (most recent call last):
  File "/home/mahaloz/ghidra_scripts/jfx_bridge/bridge.py", line 1003, in local_get
    result = getattr(target, name)
AttributeError: 'instancemethod' object has no attribute '__defaults__'
Traceback (most recent call last):
  File "/home/mahaloz/ghidra_scripts/jfx_bridge/bridge.py", line 1003, in local_get
    result = getattr(target, name)
AttributeError: 'instancemethod' object has no attribute '__kwdefaults__'
Traceback (most recent call last):
  File "/home/mahaloz/ghidra_scripts/jfx_bridge/bridge.py", line 1003, in local_get
    result = getattr(target, name)
AttributeError: 'instancemethod' object has no attribute '__text_signature__'

[justfoxing]

Yup, you can subclass Java classes remotely, this is super cursed :P Glad you've got your code sorted. Be aware that you may end up with issues if you close your ghidra bridge client while you have a callback like this registered - Ghidra will keep trying to send events to the callback, and the ghidra bridge server will throw exceptions when it finds the connection from the client closed, which can make things very sad if it's a callback that blocks the UI thread. If you do start having problems with that, check out https://github.com/justfoxing/jfx_bridge/#remoteify-and-remote-exec for an example of pushing a custom callback class onto the Ghidra-side to allow you to handle client disconnects safely.

As for the crash - hard to say without seeing the code you're using. Is it actually crashing your code, or is it just logging a bunch of AttributeErrors? IPython in particular queries for a bunch of attributes that may or may not exist as part of its amazing featureset, so a bunch of AttributeErrors are expected there.

[mahaloz]

Yeah @justfoxing, the code I used to trigger this is exactly the code you see above in an IPython instance.
As for the disconnection causing crashes after you disconnect, you are totally right; It does, lol. Thanks for the advice, I'll close the issue since those crashes aren't causing anything bad :).