Python: getting segmentation fault when using compile/eval

Question

Code:

import ast

globalsDict = {}

fAst = ast.FunctionDef(
    name="foo",
    args=ast.arguments(args=[], vararg=None, kwarg=None, defaults=[]),
    body=[], decorator_list=[])

exprAst = ast.Interactive(body=[fAst])
ast.fix_missing_locations(exprAst)
compiled = compile(exprAst, "<foo>", "single")
eval(compiled, globalsDict, globalsDict)

print globalsDict["foo"]

With both CPython and PyPy, I am getting a segmentation fault. Why?

Ferdinand Beyer · Accepted Answer · 2011-07-21 15:56:34Z

5

I guess that your function definition must not have an empty body. I tested your code by adding a no-op statement as the function body:

fAst = ast.FunctionDef(
    # ...
    body=[ast.Pass()],
    # ...

And the segmentation fault is gone; output is:

<function foo at 0x022DB3F0>

If I am correct, this could be a bug in the ast module, since it should check for the empty body.

answered Jul 21, 2011 at 15:56

Ferdinand Beyer

67.6k18 gold badges160 silver badges147 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

JAB Over a year ago

Python gives you a syntax error if you define an empty function without putting pass in the body of the function to begin with, does it not?

Ferdinand Beyer Over a year ago

It does. It won't segfault though.

Alex Gaynor Over a year ago

This is because currently ASTs aren't validated, there's an open ticket in CPython to add a validator to ASTs when you try to compile them to avoid issues like this.

Collectives™ on Stack Overflow

Python: getting segmentation fault when using compile/eval

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related