select: Actually implement extended arg to epoll.register().

Allow to pass arbitrary Python objects as "callback data" to epoll, which
will be then returned when activity on fd detected.

select/select.py

@@ -23,14 +23,19 @@ EPOLL_CTL_MOD = 3
 
 class Epoll:
 
+    # Second value is actually of uint64_t size, so struct
+    # will be smaller on 32bit, but seem to not segfault.
+    epoll_event = "IO"
+
     def __init__(self, epfd):
         self.epfd = epfd
-        self.evbuf = struct.pack("IQ", 0, 0)
+        self.evbuf = struct.pack(self.epoll_event, 0, 0)
 
     def register(self, fd, eventmask=EPOLLIN|EPOLLPRI|EPOLLOUT, retval=None):
+        "retval is extension to stdlib, value to use in results from .poll()."
         if retval is None:
             retval = fd
-        s = struct.pack("IQ", eventmask, retval)
+        s = struct.pack(self.epoll_event, eventmask, retval)
         r = epoll_ctl(self.epfd, EPOLL_CTL_ADD, fd, s)
         os.check_error(r)
 
@@ -40,8 +45,8 @@ class Epoll:
         os.check_error(n)
         res = []
         if n > 0:
-            ev, h = struct.unpack("IQ", s)
-            res.append((h, ev))
+            vals = struct.unpack(self.epoll_event, s)
+            res.append((vals[1], vals[0]))
         return res
 
 

select/setup.py

@@ -5,7 +5,7 @@ sys.path.pop(0)
 from setuptools import setup
 
 setup(name='micropython-select',
-      version='0.0.1',
+      version='0.0.2',
       description='select module to MicroPython',
       url='https://github.com/micropython/micropython/issues/405',
       author='Paul Sokolovsky',

select/test_epoll.py

@@ -3,7 +3,7 @@ import os
 
 
 ep = select.epoll()
-ep.register(0, select.EPOLLIN)
+ep.register(0, select.EPOLLIN, (lambda x:x, (0,)))
 res = ep.poll(2000)
 print(res)
 for ev, fd in res: