Making termios.tcdrain() work with threads?

[Donn Cave]

Quoth grante at visi.com (Grant Edwards):
...
| OK, the change is simple enough:
|
|     Py_BEGIN_ALLOW_THREADS
|     s = tcdrain(fd);
|     Py_END_ALLOW_THREADS
|        if (s == -1)
|            return PyErr_SetFromErrno(TermiosError);
|
|
| [similar thing done in the other 5 methods]
|
| It works just peachy now.
|
| But, before I submit a patch, I've noticed that TermiosError is
| a single, static object (file scope):
|
|     static PyObject *TermiosError;
|
| Is this going to cause problems if multiple threads have to
| return errors from the termios methods?

Don't think so!

PyEND_ALLOW_THREADS waits for the interpreter lock, so there's only
one thread at a time past that point.  PyErr_SetFromErrno should tuck
that data into the thread specific state before control gets to the
ceval loop where another thread could take over.  And I wouldn't think
you'd be modifying TermiosError anyway.

As long as 's' is automatic (stack/register) storage, you're fine.

	Donn Cave, donn at u.washington.edu