Tested on Python 3.2a0 on Mac OS 10.6.4.

When you specify the most basic `file_dispatcher` and run the loop, `file_wrapper` fails because it doesn't provide the `getsockopt()` to fake being a socket.

The code
--------

import asyncore
import os

class FileDispatcher(asyncore.file_dispatcher):
    def handle_read(self):
        data = self.recv(8192)

fd = os.open('/etc/passwd', os.O_RDONLY)
s = FileDispatcher(fd)
os.close(fd)
asyncore.loop(timeout=0.01, use_poll=True, count=2)

Expected result
---------------
None, it should run OK silently.

Actual result
-------------
error: uncaptured python exception, closing channel <__main__.FileDispatcher at 0x100524e10> (<class 'AttributeError'>:'file_wrapper' object has no attribute 'getsockopt' [/opt/error-report/py3k/Lib/asyncore.py|readwrite|106] [/opt/error-report/py3k/Lib/asyncore.py|handle_write_event|449])
Traceback (most recent call last):
  File "/opt/error-report/py3k/Lib/asyncore.py", line 106, in readwrite
    obj.handle_write_event()
  File "/opt/error-report/py3k/Lib/asyncore.py", line 449, in handle_write_event
    err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
AttributeError: 'file_wrapper' object has no attribute 'getsockopt'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/error-report/error_report.py", line 11, in <module>
    asyncore.loop(timeout=0.01, use_poll=True, count=2)
  File "/opt/error-report/py3k/Lib/asyncore.py", line 214, in loop
    poll_fun(timeout, map)
  File "/opt/error-report/py3k/Lib/asyncore.py", line 195, in poll2
    readwrite(obj, flags)
  File "/opt/error-report/py3k/Lib/asyncore.py", line 119, in readwrite
    obj.handle_error()
  File "/opt/error-report/py3k/Lib/asyncore.py", line 489, in handle_error
    self.handle_close()
  File "/opt/error-report/py3k/Lib/asyncore.py", line 508, in handle_close
    self.close()
  File "/opt/error-report/py3k/Lib/asyncore.py", line 396, in close
    self.socket.close()
  File "/opt/error-report/py3k/Lib/asyncore.py", line 617, in close
    os.close(self.fd)
OSError: [Errno 9] Bad file descriptor

Patch
-----
Please find attached a patch that does add a unit test for this specific case and adds the most simple `getsockopt()` possible that is still reasonable. The patch was made with trunk r83090.

Here goes the patch.

Patch updated to conform with the new test layout by Ezio Melotti. Implementation now also doesn't use assertions but regular exceptions.

Looks good to me.

Applied in r83201. Thanks!