posixbase._UnixWaker.connectionLost catches wrong exception.

New submission from jerub <[email protected]>:

This code from twisted.internet.posixbase._UnixWaker.conncetionLost:
{{{
    def connectionLost(self, reason):
        """Close both ends of my pipe.
        """
        if not hasattr(self, "o"):
            return
        for fd in self.i, self.o:
            try:
                os.close(fd)
            except IOError:
                pass
        del self.i, self.o
}}}

This closes both ends of the pipe by using {{{os.close()}}} and supresses errors by catching and throwing away {{{IOError}}}.

But running through the python source (2.6.1) shows me from {{{posixmodule.c}}}
{{{
static PyObject *
posix_close(PyObject *self, PyObject *args)
{
	int fd, res;
	if (!PyArg_ParseTuple(args, "i:close", &fd))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	res = close(fd);
	Py_END_ALLOW_THREADS
	if (res < 0)
		return posix_error();
	Py_INCREF(Py_None);
	return Py_None;
}
}}}

Two exceptions can be thrown, one from arg parsing (not an issue here) and one managed by {{{posix_error()}}}.

Posix error is:
{{{
static PyObject *
posix_error(void)
{
	return PyErr_SetFromErrno(PyExc_OSError);
}
}}}

Which can only be an OSError.

This has caused a traceback for me in a production piece of software.

----------
Type     : enhancement
Component: core
Keywords : 
Priority : normal
Nosy     : 
----------
http://twistedmatrix.com/trac/ticket/3880