summary refs log tree commit diff
path: root/hurd/hurdselect.c
blob: 9790d54864121084f0b9b3c0edce8a8784d3a31f (plain) (blame)
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
/* Guts of both `select' and `poll' for Hurd.
   Copyright (C) 1991-2021 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <sys/time.h>
#include <sys/types.h>
#include <sys/poll.h>
#include <hurd.h>
#include <hurd/fd.h>
#include <hurd/io_request.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <stdint.h>
#include <limits.h>
#include <time.h>
#include <sysdep-cancel.h>

/* All user select types.  */
#define SELECT_ALL (SELECT_READ | SELECT_WRITE | SELECT_URG)

/* Used to record that a particular select rpc returned.  Must be distinct
   from SELECT_ALL (which better not have the high bit set).  */
#define SELECT_RETURNED ((SELECT_ALL << 1) & ~SELECT_ALL)
#define SELECT_ERROR (SELECT_RETURNED << 1)

/* Check the first NFDS descriptors either in POLLFDS (if nonnnull) or in
   each of READFDS, WRITEFDS, EXCEPTFDS that is nonnull.  If TIMEOUT is not
   NULL, time out after waiting the interval specified therein.  Returns
   the number of ready descriptors, or -1 for errors.  */
int
_hurd_select (int nfds,
	      struct pollfd *pollfds,
	      fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
	      const struct timespec *timeout, const sigset_t *sigmask)
{
  int i;
  mach_port_t portset, sigport;
  int got, ready;
  error_t err;
  fd_set rfds, wfds, xfds;
  int firstfd, lastfd;
  mach_msg_id_t reply_msgid;
  mach_msg_timeout_t to;
  struct timespec ts;
  struct
    {
      struct hurd_userlink ulink;
      struct hurd_fd *cell;
      mach_port_t io_port;
      int type;
      mach_port_t reply_port;
      int error;
    } d[nfds];
  sigset_t oset;
  struct hurd_sigstate *ss;

  union typeword		/* Use this to avoid unkosher casts.  */
    {
      mach_msg_type_t type;
      uint32_t word;
    };
  assert (sizeof (union typeword) == sizeof (mach_msg_type_t));
  assert (sizeof (uint32_t) == sizeof (mach_msg_type_t));

  if (nfds < 0 || (pollfds == NULL && nfds > FD_SETSIZE))
    {
      errno = EINVAL;
      return -1;
    }

#define IO_SELECT_REPLY_MSGID (21012 + 100) /* XXX */
#define IO_SELECT_TIMEOUT_REPLY_MSGID (21031 + 100) /* XXX */

  if (timeout == NULL)
    reply_msgid = IO_SELECT_REPLY_MSGID;
  else
    {
      struct timespec now;

      if (timeout->tv_sec < 0 || ! valid_nanoseconds (timeout->tv_nsec))
	{
	  errno = EINVAL;
	  return -1;
	}

      err = __clock_gettime (CLOCK_REALTIME, &now);
      if (err)
	return -1;

      ts.tv_sec = now.tv_sec + timeout->tv_sec;
      ts.tv_nsec = now.tv_nsec + timeout->tv_nsec;

      if (ts.tv_nsec >= 1000000000)
	{
	  ts.tv_sec++;
	  ts.tv_nsec -= 1000000000;
	}

      if (ts.tv_sec < 0)
	ts.tv_sec = LONG_MAX; /* XXX */

      reply_msgid = IO_SELECT_TIMEOUT_REPLY_MSGID;
    }

  if (sigmask)
    {
      /* Add a port to the portset for the case when we get the signal even
         before calling __mach_msg.  */

      sigport = __mach_reply_port ();

      ss = _hurd_self_sigstate ();
      _hurd_sigstate_lock (ss);
      /* And tell the signal thread to message us when a signal arrives.  */
      ss->suspended = sigport;
      _hurd_sigstate_unlock (ss);

      if (__sigprocmask (SIG_SETMASK, sigmask, &oset))
	{
	  _hurd_sigstate_lock (ss);
	  ss->suspended = MACH_PORT_NULL;
	  _hurd_sigstate_unlock (ss);
	  __mach_port_destroy (__mach_task_self (), sigport);
	  return -1;
	}
    }
  else
    sigport = MACH_PORT_NULL;

  if (pollfds)
    {
      int error = 0;
      /* Collect interesting descriptors from the user's `pollfd' array.
	 We do a first pass that reads the user's array before taking
	 any locks.  The second pass then only touches our own stack,
	 and gets the port references.  */

      for (i = 0; i < nfds; ++i)
	if (pollfds[i].fd >= 0)
	  {
	    int type = 0;
	    if (pollfds[i].events & POLLIN)
	      type |= SELECT_READ;
	    if (pollfds[i].events & POLLOUT)
	      type |= SELECT_WRITE;
	    if (pollfds[i].events & POLLPRI)
	      type |= SELECT_URG;

	    d[i].io_port = pollfds[i].fd;
	    d[i].type = type;
	  }
	else
	  d[i].type = 0;

      HURD_CRITICAL_BEGIN;
      __mutex_lock (&_hurd_dtable_lock);

      for (i = 0; i < nfds; ++i)
	if (d[i].type != 0)
	  {
	    const int fd = (int) d[i].io_port;

	    if (fd < _hurd_dtablesize)
	      {
		d[i].cell = _hurd_dtable[fd];
		if (d[i].cell != NULL)
		  {
		    d[i].io_port = _hurd_port_get (&d[i].cell->port,
						   &d[i].ulink);
		    if (d[i].io_port != MACH_PORT_NULL)
		      continue;
		  }
	      }

	    /* Bogus descriptor, make it EBADF already.  */
	    d[i].error = EBADF;
	    d[i].type = SELECT_ERROR;
	    error = 1;
	  }

      __mutex_unlock (&_hurd_dtable_lock);
      HURD_CRITICAL_END;

      if (error)
	{
	  /* Set timeout to 0.  */
	  err = __clock_gettime (CLOCK_REALTIME, &ts);
	  if (err)
	    {
	      /* Really bad luck.  */
	      err = errno;
	      HURD_CRITICAL_BEGIN;
	      __mutex_lock (&_hurd_dtable_lock);
	      while (i-- > 0)
		if (d[i].type & ~SELECT_ERROR != 0)
		  _hurd_port_free (&d[i].cell->port, &d[i].ulink,
				   d[i].io_port);
	      __mutex_unlock (&_hurd_dtable_lock);
	      HURD_CRITICAL_END;
	      if (sigmask)
		__sigprocmask (SIG_SETMASK, &oset, NULL);
	      errno = err;
	      return -1;
	    }
	  reply_msgid = IO_SELECT_TIMEOUT_REPLY_MSGID;
	}

      lastfd = i - 1;
      firstfd = i == 0 ? lastfd : 0;
    }
  else
    {
      /* Collect interested descriptors from the user's fd_set arguments.
	 Use local copies so we can't crash from user bogosity.  */

      if (readfds == NULL)
	FD_ZERO (&rfds);
      else
	rfds = *readfds;
      if (writefds == NULL)
	FD_ZERO (&wfds);
      else
	wfds = *writefds;
      if (exceptfds == NULL)
	FD_ZERO (&xfds);
      else
	xfds = *exceptfds;

      HURD_CRITICAL_BEGIN;
      __mutex_lock (&_hurd_dtable_lock);

      /* Collect the ports for interesting FDs.  */
      firstfd = lastfd = -1;
      for (i = 0; i < nfds; ++i)
	{
	  int type = 0;
	  if (readfds != NULL && FD_ISSET (i, &rfds))
	    type |= SELECT_READ;
	  if (writefds != NULL && FD_ISSET (i, &wfds))
	    type |= SELECT_WRITE;
	  if (exceptfds != NULL && FD_ISSET (i, &xfds))
	    type |= SELECT_URG;
	  d[i].type = type;
	  if (type)
	    {
	      if (i < _hurd_dtablesize)
		{
		  d[i].cell = _hurd_dtable[i];
		  if (d[i].cell != NULL)
		    d[i].io_port = _hurd_port_get (&d[i].cell->port,
						   &d[i].ulink);
		}
	      if (i >= _hurd_dtablesize || d[i].cell == NULL ||
		  d[i].io_port == MACH_PORT_NULL)
		{
		  /* If one descriptor is bogus, we fail completely.  */
		  while (i-- > 0)
		    if (d[i].type != 0)
		      _hurd_port_free (&d[i].cell->port, &d[i].ulink,
				       d[i].io_port);
		  break;
		}
	      lastfd = i;
	      if (firstfd == -1)
		firstfd = i;
	    }
	}

      __mutex_unlock (&_hurd_dtable_lock);
      HURD_CRITICAL_END;

      if (i < nfds)
	{
	  if (sigmask)
	    __sigprocmask (SIG_SETMASK, &oset, NULL);
	  errno = EBADF;
	  return -1;
	}

      if (nfds > _hurd_dtablesize)
	nfds = _hurd_dtablesize;
    }


  err = 0;
  got = 0;

  /* Send them all io_select request messages.  */

  if (firstfd == -1)
    {
      if (sigport == MACH_PORT_NULL)
	/* But not if there were no ports to deal with at all.
	   We are just a pure timeout.  */
	portset = __mach_reply_port ();
      else
	portset = sigport;
    }
  else
    {
      portset = MACH_PORT_NULL;

      for (i = firstfd; i <= lastfd; ++i)
	if (!(d[i].type & ~SELECT_ERROR))
	  d[i].reply_port = MACH_PORT_NULL;
	else
	  {
	    int type = d[i].type;
	    d[i].reply_port = __mach_reply_port ();
	    if (timeout == NULL)
	      err = __io_select_request (d[i].io_port, d[i].reply_port, type);
	    else
	      err = __io_select_timeout_request (d[i].io_port, d[i].reply_port,
						 ts, type);
	    if (!err)
	      {
		if (firstfd == lastfd && sigport == MACH_PORT_NULL)
		  /* When there's a single descriptor, we don't need a
		     portset, so just pretend we have one, but really
		     use the single reply port.  */
		  portset = d[i].reply_port;
		else if (got == 0)
		  /* We've got multiple reply ports, so we need a port set to
		     multiplex them.  */
		  {
		    /* We will wait again for a reply later.  */
		    if (portset == MACH_PORT_NULL)
		      /* Create the portset to receive all the replies on.  */
		      err = __mach_port_allocate (__mach_task_self (),
						  MACH_PORT_RIGHT_PORT_SET,
						  &portset);
		    if (! err)
		      /* Put this reply port in the port set.  */
		      __mach_port_move_member (__mach_task_self (),
					       d[i].reply_port, portset);
		  }
	      }
	    else
	      {
		/* No error should happen, but record it for later
		   processing.  */
		d[i].error = err;
		d[i].type |= SELECT_ERROR;
		++got;
	      }
	    _hurd_port_free (&d[i].cell->port, &d[i].ulink, d[i].io_port);
	  }

      if (got == 0 && sigport != MACH_PORT_NULL)
	{
	  if (portset == MACH_PORT_NULL)
	    /* Create the portset to receive the signal message on.  */
	    __mach_port_allocate (__mach_task_self (), MACH_PORT_RIGHT_PORT_SET,
				  &portset);
	  /* Put the signal reply port in the port set.  */
	  __mach_port_move_member (__mach_task_self (), sigport, portset);
	}
    }

  /* GOT is the number of replies (or errors), while READY is the number of
     replies with at least one type bit set.  */
  ready = 0;

  /* Now wait for reply messages.  */
  if (!err && got == 0)
    {
      /* Now wait for io_select_reply messages on PORT,
	 timing out as appropriate.  */

      union
	{
	  mach_msg_header_t head;
#ifdef MACH_MSG_TRAILER_MINIMUM_SIZE
	  struct
	    {
	      mach_msg_header_t head;
	      NDR_record_t ndr;
	      error_t err;
	    } error;
	  struct
	    {
	      mach_msg_header_t head;
	      NDR_record_t ndr;
	      error_t err;
	      int result;
	      mach_msg_trailer_t trailer;
	    } success;
#else
	  struct
	    {
	      mach_msg_header_t head;
	      union typeword err_type;
	      error_t err;
	    } error;
	  struct
	    {
	      mach_msg_header_t head;
	      union typeword err_type;
	      error_t err;
	      union typeword result_type;
	      int result;
	    } success;
#endif
	} msg;
      mach_msg_option_t options;
      error_t msgerr;

      /* We rely on servers to implement the timeout, but when there are none,
	 do it on the client side.  */
      if (timeout != NULL && firstfd == -1)
	{
	  options = MACH_RCV_TIMEOUT;
	  to = timeout->tv_sec * 1000 + (timeout->tv_nsec + 999999) / 1000000;
	}
      else
	{
	  options = 0;
	  to = MACH_MSG_TIMEOUT_NONE;
	}

      int cancel_oldtype = LIBC_CANCEL_ASYNC();
      while ((msgerr = __mach_msg (&msg.head,
				   MACH_RCV_MSG | MACH_RCV_INTERRUPT | options,
				   0, sizeof msg, portset, to,
				   MACH_PORT_NULL)) == MACH_MSG_SUCCESS)
	{
	  LIBC_CANCEL_RESET (cancel_oldtype);

	  /* We got a message.  Decode it.  */
#ifdef MACH_MSG_TYPE_BIT
	  const union typeword inttype =
	  { type:
	    { MACH_MSG_TYPE_INTEGER_T, sizeof (integer_t) * 8, 1, 1, 0, 0 }
	  };
#endif

	  if (sigport != MACH_PORT_NULL && sigport == msg.head.msgh_local_port)
	    {
	      /* We actually got interrupted by a signal before
		 __mach_msg; poll for further responses and then
		 return quickly. */
	      err = EINTR;
	      goto poll;
	    }

	  if (msg.head.msgh_id == reply_msgid
	      && msg.head.msgh_size >= sizeof msg.error
	      && !(msg.head.msgh_bits & MACH_MSGH_BITS_COMPLEX)
#ifdef MACH_MSG_TYPE_BIT
	      && msg.error.err_type.word == inttype.word
#endif
	      )
	    {
	      /* This is a properly formatted message so far.
		 See if it is a success or a failure.  */
	      if (msg.error.err == EINTR
		  && msg.head.msgh_size == sizeof msg.error)
		{
		  /* EINTR response; poll for further responses
		     and then return quickly.  */
		  err = EINTR;
		  goto poll;
		}
	      /* Keep in mind msg.success.result can be 0 if a timeout
		 occurred.  */
	      if (msg.error.err
#ifdef MACH_MSG_TYPE_BIT
		  || msg.success.result_type.word != inttype.word
#endif
		  || msg.head.msgh_size != sizeof msg.success)
		{
		  /* Error or bogus reply.  */
		  if (!msg.error.err)
		    msg.error.err = EIO;
		  __mach_msg_destroy (&msg.head);
		}

	      /* Look up the respondent's reply port and record its
		 readiness.  */
	      {
		int had = got;
		if (firstfd != -1)
		  for (i = firstfd; i <= lastfd; ++i)
		    if (d[i].type
			&& d[i].reply_port == msg.head.msgh_local_port)
		      {
			if (msg.error.err)
			  {
			    d[i].error = msg.error.err;
			    d[i].type = SELECT_ERROR;
			    ++ready;
			  }
			else
			  {
			    d[i].type &= msg.success.result;
			    if (d[i].type)
			      ++ready;
			  }

			d[i].type |= SELECT_RETURNED;
			++got;
		      }
		assert (got > had);
	      }
	    }

	  if (msg.head.msgh_remote_port != MACH_PORT_NULL)
	    __mach_port_deallocate (__mach_task_self (),
				    msg.head.msgh_remote_port);

	  if (got)
	  poll:
	    {
	      /* Poll for another message.  */
	      to = 0;
	      options |= MACH_RCV_TIMEOUT;
	    }
	}
      LIBC_CANCEL_RESET (cancel_oldtype);

      if (msgerr == MACH_RCV_INTERRUPTED)
	/* Interruption on our side (e.g. signal reception).  */
	err = EINTR;

      if (ready)
	/* At least one descriptor is known to be ready now, so we will
	   return success.  */
	err = 0;
    }

  if (firstfd != -1)
    for (i = firstfd; i <= lastfd; ++i)
      if (d[i].reply_port != MACH_PORT_NULL)
	__mach_port_destroy (__mach_task_self (), d[i].reply_port);

  if (sigport != MACH_PORT_NULL)
    {
      _hurd_sigstate_lock (ss);
      ss->suspended = MACH_PORT_NULL;
      _hurd_sigstate_unlock (ss);
      __mach_port_destroy (__mach_task_self (), sigport);
    }

  if ((firstfd == -1 && sigport == MACH_PORT_NULL)
      || ((firstfd != lastfd || sigport != MACH_PORT_NULL) && portset != MACH_PORT_NULL))
    /* Destroy PORTSET, but only if it's not actually the reply port for a
       single descriptor (in which case it's destroyed in the previous loop;
       not doing it here is just a bit more efficient).  */
    __mach_port_destroy (__mach_task_self (), portset);

  if (err)
    {
      if (sigmask)
	__sigprocmask (SIG_SETMASK, &oset, NULL);
      return __hurd_fail (err);
    }

  if (pollfds)
    /* Fill in the `revents' members of the user's array.  */
    for (i = 0; i < nfds; ++i)
      {
	int type = d[i].type;
	int_fast16_t revents = 0;

	if (type & SELECT_ERROR)
	  switch (d[i].error)
	    {
	      case EPIPE:
		revents = POLLHUP;
		break;
	      case EBADF:
		revents = POLLNVAL;
		break;
	      default:
		revents = POLLERR;
		break;
	    }
	else
	  if (type & SELECT_RETURNED)
	    {
	      if (type & SELECT_READ)
		revents |= POLLIN;
	      if (type & SELECT_WRITE)
		revents |= POLLOUT;
	      if (type & SELECT_URG)
		revents |= POLLPRI;
	    }

	pollfds[i].revents = revents;
      }
  else
    {
      /* Below we recalculate READY to include an increment for each operation
	 allowed on each fd.  */
      ready = 0;

      /* Set the user bitarrays.  We only ever have to clear bits, as all
	 desired ones are initially set.  */
      if (firstfd != -1)
	for (i = firstfd; i <= lastfd; ++i)
	  {
	    int type = d[i].type;

	    if ((type & SELECT_RETURNED) == 0)
	      type = 0;

	    /* Callers of select don't expect to see errors, so we simulate
	       readiness of the erring object and the next call hopefully
	       will get the error again.  */
	    if (type & SELECT_ERROR)
	      {
		type = 0;
		if (readfds != NULL && FD_ISSET (i, readfds))
		  type |= SELECT_READ;
		if (writefds != NULL && FD_ISSET (i, writefds))
		  type |= SELECT_WRITE;
		if (exceptfds != NULL && FD_ISSET (i, exceptfds))
		  type |= SELECT_URG;
	      }

	    if (type & SELECT_READ)
	      ready++;
	    else if (readfds)
	      FD_CLR (i, readfds);
	    if (type & SELECT_WRITE)
	      ready++;
	    else if (writefds)
	      FD_CLR (i, writefds);
	    if (type & SELECT_URG)
	      ready++;
	    else if (exceptfds)
	      FD_CLR (i, exceptfds);
	  }
    }

  if (sigmask && __sigprocmask (SIG_SETMASK, &oset, NULL))
    return -1;

  return ready;
}