summaryrefslogtreecommitdiffstats
path: root/Modules/selectmodule.c
blob: 4a04af179c4072887a2ce826b692af8fd4351f61 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
/* select - Module containing unix select(2) call.
   Under Unix, the file descriptors are small integers.
   Under Win32, select only exists for sockets, and sockets may
   have any value except INVALID_SOCKET.
   Under BeOS, we suffer the same dichotomy as Win32; sockets can be anything
   >= 0.
*/

#include "Python.h"

#ifdef __APPLE__
    /* Perform runtime testing for a broken poll on OSX to make it easier
     * to use the same binary on multiple releases of the OS.
     */
#undef HAVE_BROKEN_POLL
#endif

/* Windows #defines FD_SETSIZE to 64 if FD_SETSIZE isn't already defined.
   64 is too small (too many people have bumped into that limit).
   Here we boost it.
   Users who want even more than the boosted limit should #define
   FD_SETSIZE higher before this; e.g., via compiler /D switch.
*/
#if defined(MS_WINDOWS) && !defined(FD_SETSIZE)
#define FD_SETSIZE 512
#endif 

#if defined(HAVE_POLL_H)
#include <poll.h>
#elif defined(HAVE_SYS_POLL_H)
#include <sys/poll.h>
#endif

#ifdef __sgi
/* This is missing from unistd.h */
extern void bzero(void *, int);
#endif

#ifndef DONT_HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#if defined(PYOS_OS2) && !defined(PYCC_GCC)
#include <sys/time.h>
#include <utils.h>
#endif

#ifdef MS_WINDOWS
#include <winsock.h>
#else
#ifdef __BEOS__
#include <net/socket.h>
#define SOCKET int
#else
#define SOCKET int
#endif
#endif


static PyObject *SelectError;

/* list of Python objects and their file descriptor */
typedef struct {
	PyObject *obj;			     /* owned reference */
	SOCKET fd;
	int sentinel;			     /* -1 == sentinel */
} pylist;

static void
reap_obj(pylist fd2obj[FD_SETSIZE + 1])
{
	int i;
	for (i = 0; i < FD_SETSIZE + 1 && fd2obj[i].sentinel >= 0; i++) {
		Py_XDECREF(fd2obj[i].obj);
		fd2obj[i].obj = NULL;
	}
	fd2obj[0].sentinel = -1;
}


/* returns -1 and sets the Python exception if an error occurred, otherwise
   returns a number >= 0
*/
static int
seq2set(PyObject *seq, fd_set *set, pylist fd2obj[FD_SETSIZE + 1])
{
	int i;
	int max = -1;
	int index = 0;
        int len = -1;
        PyObject* fast_seq = NULL;
	PyObject* o = NULL;

	fd2obj[0].obj = (PyObject*)0;	     /* set list to zero size */
	FD_ZERO(set);

        fast_seq=PySequence_Fast(seq, "arguments 1-3 must be sequences");
        if (!fast_seq)
            return -1;

        len = PySequence_Fast_GET_SIZE(fast_seq);

	for (i = 0; i < len; i++)  {
		SOCKET v;

		/* any intervening fileno() calls could decr this refcnt */
		if (!(o = PySequence_Fast_GET_ITEM(fast_seq, i)))
                    return -1;

		Py_INCREF(o);
		v = PyObject_AsFileDescriptor( o );
		if (v == -1) goto finally;

#if defined(_MSC_VER)
		max = 0;		     /* not used for Win32 */
#else  /* !_MSC_VER */
		if (v < 0 || v >= FD_SETSIZE) {
			PyErr_SetString(PyExc_ValueError,
				    "filedescriptor out of range in select()");
			goto finally;
		}
		if (v > max)
			max = v;
#endif /* _MSC_VER */
		FD_SET(v, set);

		/* add object and its file descriptor to the list */
		if (index >= FD_SETSIZE) {
			PyErr_SetString(PyExc_ValueError,
				      "too many file descriptors in select()");
			goto finally;
		}
		fd2obj[index].obj = o;
		fd2obj[index].fd = v;
		fd2obj[index].sentinel = 0;
		fd2obj[++index].sentinel = -1;
	}
        Py_DECREF(fast_seq);
	return max+1;

  finally:
	Py_XDECREF(o);
        Py_DECREF(fast_seq);
	return -1;
}

/* returns NULL and sets the Python exception if an error occurred */
static PyObject *
set2list(fd_set *set, pylist fd2obj[FD_SETSIZE + 1])
{
	int i, j, count=0;
	PyObject *list, *o;
	SOCKET fd;

	for (j = 0; fd2obj[j].sentinel >= 0; j++) {
		if (FD_ISSET(fd2obj[j].fd, set))
			count++;
	}
	list = PyList_New(count);
	if (!list)
		return NULL;

	i = 0;
	for (j = 0; fd2obj[j].sentinel >= 0; j++) {
		fd = fd2obj[j].fd;
		if (FD_ISSET(fd, set)) {
#ifndef _MSC_VER
			if (fd > FD_SETSIZE) {
				PyErr_SetString(PyExc_SystemError,
			   "filedescriptor out of range returned in select()");
				goto finally;
			}
#endif
			o = fd2obj[j].obj;
			fd2obj[j].obj = NULL;
			/* transfer ownership */
			if (PyList_SetItem(list, i, o) < 0)
				goto finally;

			i++;
		}
	}
	return list;
  finally:
	Py_DECREF(list);
	return NULL;
}

#undef SELECT_USES_HEAP
#if FD_SETSIZE > 1024
#define SELECT_USES_HEAP
#endif /* FD_SETSIZE > 1024 */

static PyObject *
select_select(PyObject *self, PyObject *args)
{
#ifdef SELECT_USES_HEAP
	pylist *rfd2obj, *wfd2obj, *efd2obj;
#else  /* !SELECT_USES_HEAP */
	/* XXX: All this should probably be implemented as follows:
	 * - find the highest descriptor we're interested in
	 * - add one
	 * - that's the size
	 * See: Stevens, APitUE, $12.5.1
	 */
	pylist rfd2obj[FD_SETSIZE + 1];
	pylist wfd2obj[FD_SETSIZE + 1];
	pylist efd2obj[FD_SETSIZE + 1];
#endif /* SELECT_USES_HEAP */
	PyObject *ifdlist, *ofdlist, *efdlist;
	PyObject *ret = NULL;
	PyObject *tout = Py_None;
	fd_set ifdset, ofdset, efdset;
	double timeout;
	struct timeval tv, *tvp;
	long seconds;
	int imax, omax, emax, max;
	int n;

	/* convert arguments */
	if (!PyArg_ParseTuple(args, "OOO|O:select",
			      &ifdlist, &ofdlist, &efdlist, &tout))
		return NULL;

	if (tout == Py_None)
		tvp = (struct timeval *)0;
	else if (!PyNumber_Check(tout)) {
		PyErr_SetString(PyExc_TypeError,
				"timeout must be a float or None");
		return NULL;
	}
	else {
		timeout = PyFloat_AsDouble(tout);
		if (timeout == -1 && PyErr_Occurred())
			return NULL;
		if (timeout > (double)LONG_MAX) {
			PyErr_SetString(PyExc_OverflowError,
					"timeout period too long");
			return NULL;
		}
		seconds = (long)timeout;
		timeout = timeout - (double)seconds;
		tv.tv_sec = seconds;
		tv.tv_usec = (long)(timeout*1000000.0);
		tvp = &tv;
	}


#ifdef SELECT_USES_HEAP
	/* Allocate memory for the lists */
	rfd2obj = PyMem_NEW(pylist, FD_SETSIZE + 1);
	wfd2obj = PyMem_NEW(pylist, FD_SETSIZE + 1);
	efd2obj = PyMem_NEW(pylist, FD_SETSIZE + 1);
	if (rfd2obj == NULL || wfd2obj == NULL || efd2obj == NULL) {
		if (rfd2obj) PyMem_DEL(rfd2obj);
		if (wfd2obj) PyMem_DEL(wfd2obj);
		if (efd2obj) PyMem_DEL(efd2obj);
		return PyErr_NoMemory();
	}
#endif /* SELECT_USES_HEAP */
	/* Convert sequences to fd_sets, and get maximum fd number
	 * propagates the Python exception set in seq2set()
	 */
	rfd2obj[0].sentinel = -1;
	wfd2obj[0].sentinel = -1;
	efd2obj[0].sentinel = -1;
	if ((imax=seq2set(ifdlist, &ifdset, rfd2obj)) < 0) 
		goto finally;
	if ((omax=seq2set(ofdlist, &ofdset, wfd2obj)) < 0) 
		goto finally;
	if ((emax=seq2set(efdlist, &efdset, efd2obj)) < 0) 
		goto finally;
	max = imax;
	if (omax > max) max = omax;
	if (emax > max) max = emax;

	Py_BEGIN_ALLOW_THREADS
	n = select(max, &ifdset, &ofdset, &efdset, tvp);
	Py_END_ALLOW_THREADS

#ifdef MS_WINDOWS
	if (n == SOCKET_ERROR) {
		PyErr_SetExcFromWindowsErr(SelectError, WSAGetLastError());
	}
#else
	if (n < 0) {
		PyErr_SetFromErrno(SelectError);
	}
#endif
	else if (n == 0) {
                /* optimization */
		ifdlist = PyList_New(0);
		if (ifdlist) {
			ret = PyTuple_Pack(3, ifdlist, ifdlist, ifdlist);
			Py_DECREF(ifdlist);
		}
	}
	else {
		/* any of these three calls can raise an exception.  it's more
		   convenient to test for this after all three calls... but
		   is that acceptable?
		*/
		ifdlist = set2list(&ifdset, rfd2obj);
		ofdlist = set2list(&ofdset, wfd2obj);
		efdlist = set2list(&efdset, efd2obj);
		if (PyErr_Occurred())
			ret = NULL;
		else
			ret = PyTuple_Pack(3, ifdlist, ofdlist, efdlist);

		Py_DECREF(ifdlist);
		Py_DECREF(ofdlist);
		Py_DECREF(efdlist);
	}
	
  finally:
	reap_obj(rfd2obj);
	reap_obj(wfd2obj);
	reap_obj(efd2obj);
#ifdef SELECT_USES_HEAP
	PyMem_DEL(rfd2obj);
	PyMem_DEL(wfd2obj);
	PyMem_DEL(efd2obj);
#endif /* SELECT_USES_HEAP */
	return ret;
}

#if defined(HAVE_POLL) && !defined(HAVE_BROKEN_POLL)
/* 
 * poll() support
 */

typedef struct {
	PyObject_HEAD
	PyObject *dict;
	int ufd_uptodate; 
	int ufd_len;
        struct pollfd *ufds;
} pollObject;

static PyTypeObject poll_Type;

/* Update the malloc'ed array of pollfds to match the dictionary 
   contained within a pollObject.  Return 1 on success, 0 on an error.
*/

static int
update_ufd_array(pollObject *self)
{
	Py_ssize_t i, pos;
	PyObject *key, *value;

	self->ufd_len = PyDict_Size(self->dict);
	PyMem_Resize(self->ufds, struct pollfd, self->ufd_len);
	if (self->ufds == NULL) {
		PyErr_NoMemory();
		return 0;
	}

	i = pos = 0;
	while (PyDict_Next(self->dict, &pos, &key, &value)) {
		self->ufds[i].fd = PyInt_AsLong(key);
		self->ufds[i].events = (short)PyInt_AsLong(value);
		i++;
	}
	self->ufd_uptodate = 1;
	return 1;
}

PyDoc_STRVAR(poll_register_doc,
"register(fd [, eventmask] ) -> None\n\n\
Register a file descriptor with the polling object.\n\
fd -- either an integer, or an object with a fileno() method returning an\n\
      int.\n\
events -- an optional bitmask describing the type of events to check for");

static PyObject *
poll_register(pollObject *self, PyObject *args) 
{
	PyObject *o, *key, *value;
	int fd, events = POLLIN | POLLPRI | POLLOUT;
	int err;

	if (!PyArg_ParseTuple(args, "O|i:register", &o, &events)) {
		return NULL;
	}
  
	fd = PyObject_AsFileDescriptor(o);
	if (fd == -1) return NULL;

	/* Add entry to the internal dictionary: the key is the 
	   file descriptor, and the value is the event mask. */
	key = PyInt_FromLong(fd);
	if (key == NULL)
		return NULL;
	value = PyInt_FromLong(events);
	if (value == NULL) {
		Py_DECREF(key);
		return NULL;
	}
	err = PyDict_SetItem(self->dict, key, value);
	Py_DECREF(key);
	Py_DECREF(value);
	if (err < 0)
		return NULL;

	self->ufd_uptodate = 0;
		       
	Py_INCREF(Py_None);
	return Py_None;
}

PyDoc_STRVAR(poll_unregister_doc,
"unregister(fd) -> None\n\n\
Remove a file descriptor being tracked by the polling object.");

static PyObject *
poll_unregister(pollObject *self, PyObject *args) 
{
	PyObject *o, *key;
	int fd;

	if (!PyArg_ParseTuple(args, "O:unregister", &o)) {
		return NULL;
	}
  
	fd = PyObject_AsFileDescriptor( o );
	if (fd == -1) 
		return NULL;

	/* Check whether the fd is already in the array */
	key = PyInt_FromLong(fd);
	if (key == NULL) 
		return NULL;

	if (PyDict_DelItem(self->dict, key) == -1) {
		Py_DECREF(key);
		/* This will simply raise the KeyError set by PyDict_DelItem
		   if the file descriptor isn't registered. */
		return NULL;
	}

	Py_DECREF(key);
	self->ufd_uptodate = 0;

	Py_INCREF(Py_None);
	return Py_None;
}

PyDoc_STRVAR(poll_poll_doc,
"poll( [timeout] ) -> list of (fd, event) 2-tuples\n\n\
Polls the set of registered file descriptors, returning a list containing \n\
any descriptors that have events or errors to report.");

static PyObject *
poll_poll(pollObject *self, PyObject *args) 
{
	PyObject *result_list = NULL, *tout = NULL;
	int timeout = 0, poll_result, i, j;
	PyObject *value = NULL, *num = NULL;

	if (!PyArg_ParseTuple(args, "|O:poll", &tout)) {
		return NULL;
	}

	/* Check values for timeout */
	if (tout == NULL || tout == Py_None)
		timeout = -1;
	else if (!PyNumber_Check(tout)) {
		PyErr_SetString(PyExc_TypeError,
				"timeout must be an integer or None");
		return NULL;
	}
	else {
		tout = PyNumber_Int(tout);
		if (!tout)
			return NULL;
		timeout = PyInt_AsLong(tout);
		Py_DECREF(tout);
		if (timeout == -1 && PyErr_Occurred())
			return NULL;
	}

	/* Ensure the ufd array is up to date */
	if (!self->ufd_uptodate) 
		if (update_ufd_array(self) == 0)
			return NULL;

	/* call poll() */
	Py_BEGIN_ALLOW_THREADS;
	poll_result = poll(self->ufds, self->ufd_len, timeout);
	Py_END_ALLOW_THREADS;
 
	if (poll_result < 0) {
		PyErr_SetFromErrno(SelectError);
		return NULL;
	} 
       
	/* build the result list */
  
	result_list = PyList_New(poll_result);
	if (!result_list) 
		return NULL;
	else {
		for (i = 0, j = 0; j < poll_result; j++) {
 			/* skip to the next fired descriptor */
 			while (!self->ufds[i].revents) {
 				i++;
 			}
			/* if we hit a NULL return, set value to NULL
			   and break out of loop; code at end will
			   clean up result_list */
			value = PyTuple_New(2);
			if (value == NULL)
				goto error;
			num = PyInt_FromLong(self->ufds[i].fd);
			if (num == NULL) {
				Py_DECREF(value);
				goto error;
			}
			PyTuple_SET_ITEM(value, 0, num);

			/* The &0xffff is a workaround for AIX.  'revents'
			   is a 16-bit short, and IBM assigned POLLNVAL
			   to be 0x8000, so the conversion to int results
			   in a negative number. See SF bug #923315. */
			num = PyInt_FromLong(self->ufds[i].revents & 0xffff);
			if (num == NULL) {
				Py_DECREF(value);
				goto error;
			}
			PyTuple_SET_ITEM(value, 1, num);
 			if ((PyList_SetItem(result_list, j, value)) == -1) {
				Py_DECREF(value);
				goto error;
 			}
 			i++;
 		}
 	}
 	return result_list;

  error:
	Py_DECREF(result_list);
	return NULL;
}

static PyMethodDef poll_methods[] = {
	{"register",	(PyCFunction)poll_register,	
	 METH_VARARGS,  poll_register_doc},
	{"unregister",	(PyCFunction)poll_unregister,	
	 METH_VARARGS,  poll_unregister_doc},
	{"poll",	(PyCFunction)poll_poll,	
	 METH_VARARGS,  poll_poll_doc},
	{NULL,		NULL}		/* sentinel */
};

static pollObject *
newPollObject(void)
{
        pollObject *self;
	self = PyObject_New(pollObject, &poll_Type);
	if (self == NULL)
		return NULL;
	/* ufd_uptodate is a Boolean, denoting whether the 
	   array pointed to by ufds matches the contents of the dictionary. */
	self->ufd_uptodate = 0;
	self->ufds = NULL;
	self->dict = PyDict_New();
	if (self->dict == NULL) {
		Py_DECREF(self);
		return NULL;
	}
	return self;
}

static void
poll_dealloc(pollObject *self)
{
	if (self->ufds != NULL)
		PyMem_DEL(self->ufds);
	Py_XDECREF(self->dict);
  	PyObject_Del(self);
}

static PyObject *
poll_getattr(pollObject *self, char *name)
{
	return Py_FindMethod(poll_methods, (PyObject *)self, name);
}

static PyTypeObject poll_Type = {
	/* The ob_type field must be initialized in the module init function
	 * to be portable to Windows without using C++. */
	PyObject_HEAD_INIT(NULL)
	0,			/*ob_size*/
	"select.poll",		/*tp_name*/
	sizeof(pollObject),	/*tp_basicsize*/
	0,			/*tp_itemsize*/
	/* methods */
	(destructor)poll_dealloc, /*tp_dealloc*/
	0,			/*tp_print*/
	(getattrfunc)poll_getattr, /*tp_getattr*/
	0,                      /*tp_setattr*/
	0,			/*tp_compare*/
	0,			/*tp_repr*/
	0,			/*tp_as_number*/
	0,			/*tp_as_sequence*/
	0,			/*tp_as_mapping*/
	0,			/*tp_hash*/
};

PyDoc_STRVAR(poll_doc,
"Returns a polling object, which supports registering and\n\
unregistering file descriptors, and then polling them for I/O events.");

static PyObject *
select_poll(PyObject *self, PyObject *args)
{
	pollObject *rv;
	
	if (!PyArg_ParseTuple(args, ":poll"))
		return NULL;
	rv = newPollObject();
	if ( rv == NULL )
		return NULL;
	return (PyObject *)rv;
}

#ifdef __APPLE__
/* 
 * On some systems poll() sets errno on invalid file descriptors. We test
 * for this at runtime because this bug may be fixed or introduced between
 * OS releases.
 */
static int select_have_broken_poll(void)
{
	int poll_test;
	int filedes[2];

	struct pollfd poll_struct = { 0, POLLIN|POLLPRI|POLLOUT, 0 };

	/* Create a file descriptor to make invalid */
	if (pipe(filedes) < 0) {
		return 1;
	}
	poll_struct.fd = filedes[0];
	close(filedes[0]);
	close(filedes[1]);
	poll_test = poll(&poll_struct, 1, 0);
	if (poll_test < 0) {
		return 1;
	} else if (poll_test == 0 && poll_struct.revents != POLLNVAL) {
		return 1;
	}
	return 0;
}
#endif /* __APPLE__ */

#endif /* HAVE_POLL */

PyDoc_STRVAR(select_doc,
"select(rlist, wlist, xlist[, timeout]) -> (rlist, wlist, xlist)\n\
\n\
Wait until one or more file descriptors are ready for some kind of I/O.\n\
The first three arguments are sequences of file descriptors to be waited for:\n\
rlist -- wait until ready for reading\n\
wlist -- wait until ready for writing\n\
xlist -- wait for an ``exceptional condition''\n\
If only one kind of condition is required, pass [] for the other lists.\n\
A file descriptor is either a socket or file object, or a small integer\n\
gotten from a fileno() method call on one of those.\n\
\n\
The optional 4th argument specifies a timeout in seconds; it may be\n\
a floating point number to specify fractions of seconds.  If it is absent\n\
or None, the call will never time out.\n\
\n\
The return value is a tuple of three lists corresponding to the first three\n\
arguments; each contains the subset of the corresponding file descriptors\n\
that are ready.\n\
\n\
*** IMPORTANT NOTICE ***\n\
On Windows, only sockets are supported; on Unix, all file descriptors.");

static PyMethodDef select_methods[] = {
    {"select",	select_select, METH_VARARGS, select_doc},
#if defined(HAVE_POLL) 
    {"poll",    select_poll,   METH_VARARGS, poll_doc},
#endif /* HAVE_POLL */
    {0,  	0},			     /* sentinel */
};

PyDoc_STRVAR(module_doc,
"This module supports asynchronous I/O on multiple file descriptors.\n\
\n\
*** IMPORTANT NOTICE ***\n\
On Windows, only sockets are supported; on Unix, all file descriptors.");

PyMODINIT_FUNC
initselect(void)
{
	PyObject *m;
	m = Py_InitModule3("select", select_methods, module_doc);
	if (m == NULL)
		return;

	SelectError = PyErr_NewException("select.error", NULL, NULL);
	Py_INCREF(SelectError);
	PyModule_AddObject(m, "error", SelectError);
#if defined(HAVE_POLL) 

#ifdef __APPLE__
	if (select_have_broken_poll()) {
		if (PyObject_DelAttrString(m, "poll") == -1) {
			PyErr_Clear();
		}
	} else {
#else
	{
#endif
		poll_Type.ob_type = &PyType_Type;
		PyModule_AddIntConstant(m, "POLLIN", POLLIN);
		PyModule_AddIntConstant(m, "POLLPRI", POLLPRI);
		PyModule_AddIntConstant(m, "POLLOUT", POLLOUT);
		PyModule_AddIntConstant(m, "POLLERR", POLLERR);
		PyModule_AddIntConstant(m, "POLLHUP", POLLHUP);
		PyModule_AddIntConstant(m, "POLLNVAL", POLLNVAL);

#ifdef POLLRDNORM
		PyModule_AddIntConstant(m, "POLLRDNORM", POLLRDNORM);
#endif
#ifdef POLLRDBAND
		PyModule_AddIntConstant(m, "POLLRDBAND", POLLRDBAND);
#endif
#ifdef POLLWRNORM
		PyModule_AddIntConstant(m, "POLLWRNORM", POLLWRNORM);
#endif
#ifdef POLLWRBAND
		PyModule_AddIntConstant(m, "POLLWRBAND", POLLWRBAND);
#endif
#ifdef POLLMSG
		PyModule_AddIntConstant(m, "POLLMSG", POLLMSG);
#endif
	}
#endif /* HAVE_POLL */
}