FileObjectBase raises when accessing the name property on a closed file

[danmilon]

• gevent version: 20.12.1 from pypi
• Python version: 2.7.18 from the official Fedora repos.
• Operating System: Fedora 5.8.10-200.fc32.x86_64

Description:

FileObject variants that inherit from FileObjectBase raise when accessing the name property after the file has been closed. The file object returned by io.open() doesn't have the same behavior, it returns the file path fine. This breaks some libraries (e.g. atomicwrites which rely on this behaviour.

It happens because in FileObjectCommon.close() we drop the reference to the wrapped object.

I can think of two possible fixes.

1. Don't drop the self._io reference in close(), instead set a self._closed = True flag to be used in __getattr__(), and add name in _delegate_methods().
2. In FileObjectCommon.__init__() do self.name = self._io.name.

Thoughts?

What I've run:

import gevent.monkey; gevent.monkey.patch_all()
import gevent.fileobject
import io

f = io.open("/tmp/foo", mode="w")
print("f.name by io.open before close: {}".format(f.name))
f.close()
print("f.name by io.open after close: {}".format(f.name))

f = gevent.fileobject.FileObjectThread(
    "/tmp/foo",
    mode="w",
)

print("f.name by gevent.fileobject before close: {}".format(f.name))
f.close()
print("f.name by gevent.fileobject after close: {}".format(f.name))

[jamadden]

Thanks for the report!