[Python-Dev] how important is setting co_filename for a module being imported to what file is set to? (original) (raw)

Benjamin Peterson benjamin at python.org
Mon Aug 31 04:51:00 CEST 2009

2009/8/30 Brett Cannon <brett at python.org>:

On Sun, Aug 30, 2009 at 19:34, Guido van Rossum<guido at python.org> wrote:

On Sun, Aug 30, 2009 at 5:34 PM, Brett Cannon<brett at python.org> wrote:

On Sun, Aug 30, 2009 at 17:24, Guido van Rossum<guido at python.org> wrote:

(I was going to comment on the execution bit issue but I realized I'm not even sure if you're talking about import.c or not. :-)

So it turns out a bunch of execution/write bit stuff has come up in Python 2.7 and importlib has been ignoring it. =) Importlib has simply been opening up the bytecode files with 'wb' and writing out the file. But testimport tests that no execution bit get set or that a write bit gets added if the source file lacks it. I guess I can use posix.chmod and posix.stat to copy the source file's read and write bits and always mask out the execution bits. I hate this low-level file permission stuff. It's no fun -- see the layers of #ifdefs in openexclusive() in import.c. (Though I think you won't need to worry about VMS. :-) But it's somewhat important to get it right from a security POV. I would use os.open() and wrap an io.BufferedWriter around it. I will have to see what of that is implemented in C or in Python. I have always tried to keep all pure Python code out of importlib for bootstrapping reasons in order to keep the possibility of using importlib as the implementation of import. But maybe I should not be worrying about that right at the moment and instead do what keeps the code simple.

You can use the C implementation of io, _io, which has a full buffering implementation. Of course, that also makes it a better harder for other implementations which may wish to use importlib because the io library would have to be completely implemented...

-- Regards, Benjamin

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