thr_select.c revision 48140 
1/*
2 * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by John Birrell.
16 * 4. Neither the name of the author nor the names of any co-contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * $Id: uthread_select.c,v 1.7 1999/06/20 08:28:43 jb Exp $
33 */
34#include <unistd.h>
35#include <errno.h>
36#include <poll.h>
37#include <stdlib.h>
38#include <string.h>
39#include <sys/param.h>
40#include <sys/types.h>
41#include <sys/time.h>
42#include <sys/fcntl.h>
43#ifdef _THREAD_SAFE
44#include <pthread.h>
45#include "pthread_private.h"
46
47int
48select(int numfds, fd_set * readfds, fd_set * writefds,
49       fd_set * exceptfds, struct timeval * timeout)
50{
51	struct timespec ts;
52	int             i, ret = 0, f_wait = 1;
53	int		pfd_index, got_one = 0, fd_count = 0;
54	struct pthread_poll_data data;
55
56	if (numfds > _thread_dtablesize) {
57		numfds = _thread_dtablesize;
58	}
59	/* Check if a timeout was specified: */
60	if (timeout) {
61		/* Convert the timeval to a timespec: */
62		TIMEVAL_TO_TIMESPEC(timeout, &ts);
63
64		/* Set the wake up time: */
65		_thread_kern_set_timeout(&ts);
66		if (ts.tv_sec == 0 && ts.tv_nsec == 0)
67			f_wait = 0;
68	} else {
69		/* Wait for ever: */
70		_thread_kern_set_timeout(NULL);
71	}
72
73	/* Count the number of file descriptors to be polled: */
74	if (readfds || writefds || exceptfds) {
75		for (i = 0; i < numfds; i++) {
76			if ((readfds && FD_ISSET(i, readfds)) ||
77			    (exceptfds && FD_ISSET(i, exceptfds)) ||
78			    (writefds && FD_ISSET(i, writefds))) {
79				fd_count++;
80			}
81		}
82	}
83
84	/*
85	 * Allocate memory for poll data if it hasn't already been
86	 * allocated or if previously allocated memory is insufficient.
87	 */
88	if ((_thread_run->poll_data.fds == NULL) ||
89	    (_thread_run->poll_data.nfds < fd_count)) {
90		data.fds = (struct pollfd *) realloc(_thread_run->poll_data.fds,
91		    sizeof(struct pollfd) * MAX(128, fd_count));
92		if (data.fds == NULL) {
93			errno = ENOMEM;
94			ret = -1;
95		}
96		else {
97			/*
98			 * Note that the threads poll data always
99			 * indicates what is allocated, not what is
100			 * currently being polled.
101			 */
102			_thread_run->poll_data.fds = data.fds;
103			_thread_run->poll_data.nfds = MAX(128, fd_count);
104		}
105	}
106	if (ret == 0) {
107		/* Setup the wait data. */
108		data.fds = _thread_run->poll_data.fds;
109		data.nfds = fd_count;
110
111		/*
112		 * Setup the array of pollfds.  Optimize this by
113		 * running the loop in reverse and stopping when
114		 * the number of selected file descriptors is reached.
115		 */
116		for (i = numfds - 1, pfd_index = fd_count - 1;
117		    (i >= 0) && (pfd_index >= 0); i--) {
118			data.fds[pfd_index].events = 0;
119			if (readfds && FD_ISSET(i, readfds)) {
120				data.fds[pfd_index].events = POLLRDNORM;
121			}
122			if (exceptfds && FD_ISSET(i, exceptfds)) {
123				data.fds[pfd_index].events |= POLLRDBAND;
124			}
125			if (writefds && FD_ISSET(i, writefds)) {
126				data.fds[pfd_index].events |= POLLWRNORM;
127			}
128			if (data.fds[pfd_index].events != 0) {
129				/*
130				 * Set the file descriptor to be polled and
131				 * clear revents in case of a timeout which
132				 * leaves fds unchanged:
133				 */
134				data.fds[pfd_index].fd = i;
135				data.fds[pfd_index].revents = 0;
136				pfd_index--;
137			}
138		}
139		if (((ret = _thread_sys_poll(data.fds, data.nfds, 0)) == 0) &&
140		   (f_wait != 0)) {
141			_thread_run->data.poll_data = &data;
142			_thread_run->interrupted = 0;
143			_thread_kern_sched_state(PS_SELECT_WAIT, __FILE__, __LINE__);
144			if (_thread_run->interrupted) {
145				errno = EINTR;
146				data.nfds = 0;
147				ret = -1;
148			} else
149				ret = data.nfds;
150		}
151	}
152
153	if (ret >= 0) {
154		numfds = 0;
155		for (i = 0; i < fd_count; i++) {
156			/*
157			 * Check the results of the poll and clear
158			 * this file descriptor from the fdset if
159			 * the requested event wasn't ready.
160			 */
161			got_one = 0;
162			if (readfds != NULL) {
163				if (FD_ISSET(data.fds[i].fd, readfds)) {
164					if (data.fds[i].revents & (POLLIN |
165					    POLLRDNORM))
166						got_one = 1;
167					else
168						FD_CLR(data.fds[i].fd, readfds);
169				}
170			}
171			if (writefds != NULL) {
172				if (FD_ISSET(data.fds[i].fd, writefds)) {
173					if (data.fds[i].revents & (POLLOUT |
174					    POLLWRNORM | POLLWRBAND))
175						got_one = 1;
176					else
177						FD_CLR(data.fds[i].fd,
178						    writefds);
179				}
180			}
181			if (exceptfds != NULL) {
182				if (FD_ISSET(data.fds[i].fd, exceptfds)) {
183					if (data.fds[i].revents & (POLLRDBAND |
184					    POLLPRI | POLLHUP | POLLERR |
185					    POLLNVAL))
186						got_one = 1;
187					else
188						FD_CLR(data.fds[i].fd,
189						    exceptfds);
190				}
191			}
192			if (got_one)
193				numfds++;
194		}
195		ret = numfds;
196	}
197
198	return (ret);
199}
200#endif
201