1/* `fd_set' type and related macros, and `select'/`pselect' declarations.
2 Copyright (C) 1996-2019 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 <http://www.gnu.org/licenses/>. */
18
19/* POSIX 1003.1g: 6.2 Select from File Descriptor Sets <sys/select.h> */
20
21#ifndef _SYS_SELECT_H
22#define _SYS_SELECT_H 1
23
24#include <features.h>
25
26/* Get definition of needed basic types. */
27#include <bits/types.h>
28
29/* Get __FD_* definitions. */
30#include <bits/select.h>
31
32/* Get sigset_t. */
33#include <bits/types/sigset_t.h>
34
35/* Get definition of timer specification structures. */
36#include <bits/types/time_t.h>
37#include <bits/types/struct_timeval.h>
38#ifdef __USE_XOPEN2K
39# include <bits/types/struct_timespec.h>
40#endif
41
42#ifndef __suseconds_t_defined
43typedef __suseconds_t suseconds_t;
44# define __suseconds_t_defined
45#endif
46
47
48/* The fd_set member is required to be an array of longs. */
49typedef long int __fd_mask;
50
51/* Some versions of <linux/posix_types.h> define this macros. */
52#undef __NFDBITS
53/* It's easier to assume 8-bit bytes than to get CHAR_BIT. */
54#define __NFDBITS (8 * (int) sizeof (__fd_mask))
55#define __FD_ELT(d) ((d) / __NFDBITS)
56#define __FD_MASK(d) ((__fd_mask) (1UL << ((d) % __NFDBITS)))
57
58/* fd_set for select and pselect. */
59typedef struct
60 {
61 /* XPG4.2 requires this member name. Otherwise avoid the name
62 from the global namespace. */
63#ifdef __USE_XOPEN
64 __fd_mask fds_bits[__FD_SETSIZE / __NFDBITS];
65# define __FDS_BITS(set) ((set)->fds_bits)
66#else
67 __fd_mask __fds_bits[__FD_SETSIZE / __NFDBITS];
68# define __FDS_BITS(set) ((set)->__fds_bits)
69#endif
70 } fd_set;
71
72/* Maximum number of file descriptors in `fd_set'. */
73#define FD_SETSIZE __FD_SETSIZE
74
75#ifdef __USE_MISC
76/* Sometimes the fd_set member is assumed to have this type. */
77typedef __fd_mask fd_mask;
78
79/* Number of bits per word of `fd_set' (some code assumes this is 32). */
80# define NFDBITS __NFDBITS
81#endif
82
83
84/* Access macros for `fd_set'. */
85#define FD_SET(fd, fdsetp) __FD_SET (fd, fdsetp)
86#define FD_CLR(fd, fdsetp) __FD_CLR (fd, fdsetp)
87#define FD_ISSET(fd, fdsetp) __FD_ISSET (fd, fdsetp)
88#define FD_ZERO(fdsetp) __FD_ZERO (fdsetp)
89
90
91__BEGIN_DECLS
92
93/* Check the first NFDS descriptors each in READFDS (if not NULL) for read
94 readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
95 (if not NULL) for exceptional conditions. If TIMEOUT is not NULL, time out
96 after waiting the interval specified therein. Returns the number of ready
97 descriptors, or -1 for errors.
98
99 This function is a cancellation point and therefore not marked with
100 __THROW. */
101extern int select (int __nfds, fd_set *__restrict __readfds,
102 fd_set *__restrict __writefds,
103 fd_set *__restrict __exceptfds,
104 struct timeval *__restrict __timeout);
105
106#ifdef __USE_XOPEN2K
107/* Same as above only that the TIMEOUT value is given with higher
108 resolution and a sigmask which is been set temporarily. This version
109 should be used.
110
111 This function is a cancellation point and therefore not marked with
112 __THROW. */
113extern int pselect (int __nfds, fd_set *__restrict __readfds,
114 fd_set *__restrict __writefds,
115 fd_set *__restrict __exceptfds,
116 const struct timespec *__restrict __timeout,
117 const __sigset_t *__restrict __sigmask);
118#endif
119
120
121/* Define some inlines helping to catch common problems. */
122#if __USE_FORTIFY_LEVEL > 0 && defined __GNUC__
123# include <bits/select2.h>
124#endif
125
126__END_DECLS
127
128#endif /* sys/select.h */
129