hypno 0.1.3

A tool/library allowing to inject python code into a running python process.

Hypno

A tool/library allowing to inject python code into a running python process.

Installation

pip install hypno

Both source distributions and manylinux1 wheels are upoloaded to pypi for every release.

Usage

CLI

hypno <pid> <python_code>

API

from hypno import inject_py

inject_py(pid, python_code)

Example

This example runs a python program that prints its pid, and then attaches to the newly created process and injects it with another print statement using hypno.

python -c "import os, time; print('Hello from', os.getpid()); time.sleep(0.5)" &\
hypno $! "import os; print('Hello again from', os.getpid())"

How it works

We use the pyinjector library as a primitive allowing us to inject arbitrary code into processes, because it is simple to use and can be installed easily and on most linux machines.

pyinjector needs an .so to inject, so we compile a minimal library as a C-extension. That library calls PyRun_SimpleString upon initialization.

In order to allow injecting a process multiple times, the injected library must have a unique path for each injection. We do that by copying the library for every call.

As we don't want to recompile the library for every injection to replace the executed string, and we already control the path from which our library is injected, we encode the injected python code into the the injected libraries' paths. When the injected library is loaded, it finds its own name using dladdr and parses the python code from it.