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Python WASM-WASI can't be executed from a different directory than root #100307
Description
Bug report
- install wasmtime (I used 3.0.1)
- download Python-3.11.0-wasm32-wasi-16.zip
- extract it into a directory
- cd into that directory
- run python using the following command line
wasmtime run --mapdir /::. ./python.wasm
Observe: everything works as expected. You end up in a REPL - try to 'mount' the python installation into a different directory (e.g.
/usr) by runningwasmtime run --mapdir /usr::. --env PYTHONHOME=/usr/lib/python3.11 ./python.wasm
Observe: you get
Exception ignored error evaluating path:
Traceback (most recent call last):
File "<frozen getpath>", line 471, in <module>
OSError: [Errno 76] Capabilities insufficient
Fatal Python error: error evaluating path
Python runtime state: core initialized
Current thread 0x00000000 (most recent call first):
<no Python frame>
I was not able to successfully execute Python when mounting the installation directory to something different than /
Your environment
- wasmtime 3.0.1
- Python-3.11.0-wasm32-wasi-16.zip
- WSL2 running
5.15.79.1-microsoft-standard-WSL2
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.5 LTS
Release: 20.04
Codename: focal
Activity
brettcannon commentedon Jan 13, 2023
This is caused because there's logic within Python to know where to look for the stdlib that gets baked in. As of right now that logic looks for
/libfor the stdlib, so mounting to/usrwhere thelibdirectory of a build is will cause that to fail as that would make/usr/libbe where the stdlib resides which isn't where Python will go looking.There are two possible solutions to this annoyance. One is to patch things up to be relative to the binary location somehow. The other is to embed the pure Python code into the binary. The latter would require making sure there's a way to map to the source, if available, so that tracebacks are a bit nicer (otherwise the source code lines won't show up).
[-]Python WASM-WASI can't be executed from a different directory than root.[/-][+]Python WASM-WASI can't be executed from a different directory than root[/+]brettcannon commentedon Mar 28, 2023
With the latest build for CPython 3.11.2 I have up at https://github.com/brettcannon/cpython-wasi-build this is no longer a problem: