1 /*
2  * Copyright (c) 2004, 2005, 2007 Darren Tucker (dtucker at zip com au).
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #ifdef HAVE_SYS_SELECT_H
18 # include <sys/select.h>
19 #endif
20 
21 #include <errno.h>
22 #include <stdlib.h>
23 #include <unistd.h>
24 #include "bsd-poll.h"
25 
26 #ifndef MAX
27 #define MAX(_a,_b) ((_a) > (_b) ? (_a) : (_b))
28 #endif
29 
30 #ifndef howmany
31 #define howmany(x,y) (((x)+((y)-1))/(y))
32 #endif
33 
34 /*
35  * A minimal implementation of ppoll(2), built on top of pselect(2).
36  *
37  * Only supports POLLIN, POLLOUT and POLLPRI flags in pfd.events and
38  * revents. Notably POLLERR, POLLHUP and POLLNVAL are not supported.
39  *
40  * Supports pfd.fd = -1 meaning "unused" although it's not standard.
41  */
42 
43 int
44 ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *tmoutp,
45     const sigset_t *sigmask)
46 {
47 	nfds_t i;
48 	int saved_errno, ret, fd, maxfd = 0;
49 	fd_set *readfds = NULL, *writefds = NULL, *exceptfds = NULL;
50 	size_t nmemb;
51 
52 	for (i = 0; i < nfds; i++) {
53 		fd = fds[i].fd;
54 		if (fd != -1 && fd >= FD_SETSIZE) {
55 			errno = EINVAL;
56 			return -1;
57 		}
58 		maxfd = MAX(maxfd, fd);
59 	}
60 
61 	nmemb = howmany(maxfd + 1 , NFDBITS);
62 	if ((readfds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
63 	    (writefds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
64 	    (exceptfds = calloc(nmemb, sizeof(fd_mask))) == NULL) {
65 		saved_errno = ENOMEM;
66 		ret = -1;
67 		goto out;
68 	}
69 
70 	/* populate event bit vectors for the events we're interested in */
71 	for (i = 0; i < nfds; i++) {
72 		fd = fds[i].fd;
73 		if (fd == -1)
74 			continue;
75 		if (fds[i].events & POLLIN)
76 			FD_SET(fd, readfds);
77 		if (fds[i].events & POLLOUT)
78 			FD_SET(fd, writefds);
79 		if (fds[i].events & POLLPRI)
80 			FD_SET(fd, exceptfds);
81 	}
82 
83 	ret = pselect(maxfd + 1, readfds, writefds, exceptfds, tmoutp, sigmask);
84 	saved_errno = errno;
85 
86 	/* scan through select results and set poll() flags */
87 	for (i = 0; i < nfds; i++) {
88 		fd = fds[i].fd;
89 		fds[i].revents = 0;
90 		if (fd == -1)
91 			continue;
92 		if (FD_ISSET(fd, readfds))
93 			fds[i].revents |= POLLIN;
94 		if (FD_ISSET(fd, writefds))
95 			fds[i].revents |= POLLOUT;
96 		if (FD_ISSET(fd, exceptfds))
97 			fds[i].revents |= POLLPRI;
98 	}
99 
100 out:
101 	free(readfds);
102 	free(writefds);
103 	free(exceptfds);
104 	if (ret == -1)
105 		errno = saved_errno;
106 	return ret;
107 }
108 
109 #if 0
110 int
111 poll(struct pollfd *fds, nfds_t nfds, int timeout)
112 {
113 	struct timespec ts, *tsp = NULL;
114 
115 	/* poll timeout is msec, ppoll is timespec (sec + nsec) */
116 	if (timeout >= 0) {
117 		ts.tv_sec = timeout / 1000;
118 		ts.tv_nsec = (timeout % 1000) * 1000000;
119 		tsp = &ts;
120 	}
121 
122 	return ppoll(fds, nfds, tsp, NULL);
123 }
124 #endif