Pyringe: Debugger capable of attaching to and injecting into Python processes

by codecondo • 12 years ago

120 30 12 years ago

dindresto• 12 years ago

The title is a bit misleading, since Pyringe is "only" able to inject Python code into Python processes. Aside of that, I think this could prove useful for Clojure-like live coding.

seanmcdirmid• 12 years ago

Looks more like being able to get a meta-REPL going in a running process...as could be done with LISP and Smalltalk since the 70s.

wslh2• 12 years ago

Shameless plug: my company develops Deviare[1]: "code interception for dummies". It allows to intercept a Windows application from any COM capable programming language.

We have interesting code samples such as capturing video intercepting DirectX[2] and hooking into SQL Server to abort unsecure (e.g. injection attacks) queries[3].

1. http://www.nektra.com/products/deviare-api-hook-windows/devi...

2. http://blog.nektra.com/main/2013/07/23/instrumenting-direct3...

3. http://blog.nektra.com/main/2013/06/26/sql-server-intercepti...

jevinskie2• 12 years ago

Do you know of anything similar for amd64 Mac/Linux? Not PLT hooking but the sort of deal where the beginning of the function is overwritten with a jump to the hook. The overwritten instructions in the original function are copied to a mmap()ed area of memory that jumps back past the hook jump.

I found an old copy of MobileSubstrate that has partial support for i386 and x86_64 (which works fine on Linux since the ABI is the same as Mac). I found out that it doesn't support all the possible jumps in the overwritten area. I've been slowly patching and improving it[0] but I'd rather be spending my time hooking stuff than writing the hooker.

[0] https://github.com/jevinskie/substrate

throwaway8122• 12 years ago

This is super cool. With C programs, you can already attach gdb to a running program and start debugging, without starting the program under the debugger. Before pyringe, you couldn't do the same with Python. This will be very helpful for me at work.

userbinator• 12 years ago

You could always do this with any process no matter what language it's written in. The issue is in support for debugging at a higher level.

throwaway8122• 12 years ago

Yes, sure. GDB-level debugging of Python programs, without something like Pyringe, is pretty useless. So I am excited for the Python-level tool for debugging Python.

kngl2• 12 years ago

What's wrong with http://pyrasite.com/ ?

tehmillhouse3• 12 years ago

Depending on what state cpython is in when you inject, pyrasite may deadlock or segfault the interpreter. All it does is try to get the GIL and then inject the code.

Pyringe first gets to a safe place before injecting by (essentially) faking the delivery of a signal, then waiting for python-level signal handler dispatch to trigger. By doing so, it ensures the interpreter first gets itself into a state in which it can execute arbitrary python code before performing the injection.

Pyrasite has a bunch of features pyringe doesn't, though.

kngl2• 12 years ago

Using a signal may also have side effects on your program.

socillion• 12 years ago

What I'd love to see is a version of this tool, which lets you interact with binaries, in Python:

http://duschkumpane.org/index.php/mmbbq

It's not what is posted here, just what I thought it was going to be.

albertzeyer2• 12 years ago

Note that there are already a few similar projects:

* https://github.com/albertz/pydbattach (my own :))

* PyInjector (don't find a good link right now)

* I'm quite sure I have seen at least one other similar project here on HN a while ago, but I don't remember the name...

therobotking• 12 years ago

Nice list of alternatives. Good job you managed to find a link to your own.

Fuxy• 12 years ago

Don't be a dick.

sontek• 12 years ago

This is probably the most featured / well known one:

https://github.com/lmacken/pyrasite

revelation• 12 years ago

Note that you can call PyFrame_FastToLocals if you want to access all locals. This will selectively disable fast locals on a frame.

spitfire• 12 years ago

We've been able to do this in C at runtime for decades. Just use strcpy.

Humour aside, in 10-15 years time I expect it to be considered strange not to have hot-swap features in production languages.

jjoonathan2• 12 years ago

XCode used to be able to do this with C and ObjC code, but they dropped the feature when they moved to llvm.

albertzeyer2• 12 years ago

That's interesting. Why did they drop it? Because of lacking support in LLVM? Are they planning to reimplement it? Or because of stability issues?

DannyBee2• 12 years ago

Just to note: Pyringe is not an official google project (we tend to also include googler hobby projects in the org). It's an intern's project that he wanted to open source.

So it's not "Google's Pyringe".

tehmillhouse3• 12 years ago

You're absolutely right, and I'm a colossal idiot for not making that absolutely clear.

DannyBee2• 12 years ago

You aren't an idiot, it happens :) Just don't want people to get confused.

Pyringe: Debugger capable of attaching to and injecting into Python processes

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