[doc] exec-used, can't reproduce the nefarious example writing in an intermediary file

[Pierre-Sassoulas]

Type of Changes

	Type
✓	📜 Docs

Description

I wanted to make the example's formatting better in details, ended up trying to reproduce it, but it seems the allow_globals parameters is smarter than we thought when originally documenting it. I get this error when uncommenting # allowed_globals:

Traceback (most recent call last):
  File "/home/pierre/pylint/a.py", line 4, in <module>
    exec(
  File "<string>", line 2, in <module>
SystemError: ../Objects/dictobject.c:1490: bad argument to internal function

import textwrap
allowed_globals = {"__builtins__": None}
exec(
    textwrap.dedent("""
    import textwrap

    with open("nefarious.py", "w") as f:
        f.write(textwrap.dedent('''
            def connive():
                print("Here's some code as nefarious as imaginable")
        '''))

    import nefarious
    nefarious.connive()
    """),
    allowed_globals,
)

What am I doing wrong @DanielNoord ?

[DanielNoord]

Where do you get this error? Locally this example also doesn't run? So perhaps it is just an invalid snippet?

[Pierre-Sassoulas]

I created it :) If you remove allowed_global from the exec call, it's going to work as expected (print the nefarious conniving).

[DanielNoord]

Sorry I still don't understand the issue 😅

If I run this code locally without the comment then I also get a crash. So isn't it excepted that you get some kind of (System)Error when you uncomment it?

[Pierre-Sassoulas]

Hmm not sure if it's due to mac vs Ubuntu or if there's some kind if misunderstanding. On my side it print when allowed_global is commented and crash when it's not. Maybe you can provide an exemple where print is being called inside an exec when allowed_globals should forbid it ?

[DanielNoord]

But in the old code there is no allowed_global right? So the new code without the comment is just invalid Python?