1/* Linux select implementation.
2 Copyright (C) 2017-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library. If not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <sys/time.h>
20#include <sys/types.h>
21#include <sys/select.h>
22#include <errno.h>
23#include <sysdep-cancel.h>
24
25/* Check the first NFDS descriptors each in READFDS (if not NULL) for read
26 readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
27 (if not NULL) for exceptional conditions. If TIMEOUT is not NULL, time out
28 after waiting the interval specified therein. Returns the number of ready
29 descriptors, or -1 for errors. */
30
31#ifdef __NR__newselect
32# undef __NR_select
33# define __NR_select __NR__newselect
34#endif
35
36int
37__select (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
38 struct timeval *timeout)
39{
40#ifdef __NR_select
41 return SYSCALL_CANCEL (select, nfds, readfds, writefds, exceptfds,
42 timeout);
43#else
44 int result;
45 struct timespec ts, *tsp = NULL;
46
47 if (timeout)
48 {
49 TIMEVAL_TO_TIMESPEC (timeout, &ts);
50 tsp = &ts;
51 }
52
53 result = SYSCALL_CANCEL (pselect6, nfds, readfds, writefds, exceptfds, tsp,
54 NULL);
55
56 if (timeout)
57 {
58 /* Linux by default will update the timeout after a pselect6 syscall
59 (though the pselect() glibc call suppresses this behavior).
60 Since select() on Linux has the same behavior as the pselect6
61 syscall, we update the timeout here. */
62 TIMESPEC_TO_TIMEVAL (timeout, &ts);
63 }
64
65 return result;
66#endif
67}
68libc_hidden_def (__select)
69
70weak_alias (__select, select)
71weak_alias (__select, __libc_select)
72