select.h (5049B) - Raw
1 /* `fd_set' type and related macros, and `select'/`pselect' declarations. 2 Copyright (C) 1996-2025 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 43 typedef __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. */ 49 typedef 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. */ 59 typedef 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. */ 77 typedef __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. */ 101 #ifndef __USE_TIME64_REDIRECTS 102 extern int select (int __nfds, fd_set *__restrict __readfds, 103 fd_set *__restrict __writefds, 104 fd_set *__restrict __exceptfds, 105 struct timeval *__restrict __timeout); 106 #else 107 # ifdef __REDIRECT 108 extern int __REDIRECT (select, 109 (int __nfds, fd_set *__restrict __readfds, 110 fd_set *__restrict __writefds, 111 fd_set *__restrict __exceptfds, 112 struct timeval *__restrict __timeout), 113 __select64); 114 # else 115 # define select __select64 116 # endif 117 #endif 118 119 #ifdef __USE_XOPEN2K 120 /* Same as above only that the TIMEOUT value is given with higher 121 resolution and a sigmask which is been set temporarily. This version 122 should be used. 123 124 This function is a cancellation point and therefore not marked with 125 __THROW. */ 126 # ifndef __USE_TIME64_REDIRECTS 127 extern int pselect (int __nfds, fd_set *__restrict __readfds, 128 fd_set *__restrict __writefds, 129 fd_set *__restrict __exceptfds, 130 const struct timespec *__restrict __timeout, 131 const __sigset_t *__restrict __sigmask); 132 # else 133 # ifdef __REDIRECT 134 extern int __REDIRECT (pselect, 135 (int __nfds, fd_set *__restrict __readfds, 136 fd_set *__restrict __writefds, 137 fd_set *__restrict __exceptfds, 138 const struct timespec *__restrict __timeout, 139 const __sigset_t *__restrict __sigmask), 140 __pselect64); 141 # else 142 # define pselect __pselect64 143 # endif 144 # endif 145 #endif 146 147 148 /* Define some inlines helping to catch common problems. */ 149 #if __USE_FORTIFY_LEVEL > 0 && defined __GNUC__ 150 # include <bits/select2.h> 151 #endif 152 153 __END_DECLS 154 155 #endif /* sys/select.h */