1/* `fd_set' type and related macros, and `select'/`pselect' declarations. 
2 Copyright (C) 1996-2020 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/* 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