1 /* pselect - synchronous I/O multiplexing
2
3 Copyright 2011-2023 Free Software Foundation, Inc.
4
5 This file is part of gnulib.
6
7 This file is free software: you can redistribute it and/or modify
8 it under the terms of the GNU Lesser General Public License as
9 published by the Free Software Foundation; either version 2.1 of the
10 License, or (at your option) any later version.
11
12 This file is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU Lesser General Public License for more details.
16
17 You should have received a copy of the GNU Lesser General Public License
18 along with this program. If not, see <https://www.gnu.org/licenses/>. */
19
20 /* written by Paul Eggert */
21
22 #include <config.h>
23
24 #include <sys/select.h>
25
26 #include <errno.h>
27 #include <signal.h>
28
29 /* Examine the size-NFDS file descriptor sets in RFDS, WFDS, and XFDS
30 to see whether some of their descriptors are ready for reading,
31 ready for writing, or have exceptions pending. Wait for at most
32 TIMEOUT seconds, and use signal mask SIGMASK while waiting. A null
33 pointer parameter stands for no descriptors, an infinite timeout,
34 or an unaffected signal mask. */
35
36 #if !HAVE_PSELECT
37
38 int
39 pselect (int nfds, fd_set *restrict rfds,
40 fd_set *restrict wfds, fd_set *restrict xfds,
41 struct timespec const *restrict timeout,
42 sigset_t const *restrict sigmask)
43 {
44 int select_result;
45 sigset_t origmask;
46 struct timeval tv, *tvp;
47
48 if (nfds < 0 || nfds > FD_SETSIZE)
49 {
50 errno = EINVAL;
51 return -1;
52 }
53
54 if (timeout)
55 {
56 if (! (0 <= timeout->tv_nsec && timeout->tv_nsec < 1000000000))
57 {
58 errno = EINVAL;
59 return -1;
60 }
61
62 tv = (struct timeval) {
63 .tv_sec = timeout->tv_sec,
64 .tv_usec = (timeout->tv_nsec + 999) / 1000
65 };
66 tvp = &tv;
67 }
68 else
69 tvp = NULL;
70
71 /* Signal mask munging should be atomic, but this is the best we can
72 do in this emulation. */
73 if (sigmask)
74 pthread_sigmask (SIG_SETMASK, sigmask, &origmask);
75
76 select_result = select (nfds, rfds, wfds, xfds, tvp);
77
78 if (sigmask)
79 {
80 int select_errno = errno;
81 pthread_sigmask (SIG_SETMASK, &origmask, NULL);
82 errno = select_errno;
83 }
84
85 return select_result;
86 }
87
88 #else /* HAVE_PSELECT */
89 # include <unistd.h>
90 # undef pselect
91
92 int
93 rpl_pselect (int nfds, fd_set *restrict rfds,
94 fd_set *restrict wfds, fd_set *restrict xfds,
95 struct timespec const *restrict timeout,
96 sigset_t const *restrict sigmask)
97 {
98 int i;
99
100 /* FreeBSD 8.2 has a bug: it does not always detect invalid fds. */
101 if (nfds < 0 || nfds > FD_SETSIZE)
102 {
103 errno = EINVAL;
104 return -1;
105 }
106 for (i = 0; i < nfds; i++)
107 {
108 if (((rfds && FD_ISSET (i, rfds))
109 || (wfds && FD_ISSET (i, wfds))
110 || (xfds && FD_ISSET (i, xfds)))
111 && dup2 (i, i) != i)
112 return -1;
113 }
114
115 return pselect (nfds, rfds, wfds, xfds, timeout, sigmask);
116 }
117
118 #endif