1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #pragma once 30 31 /** 32 * @file sys/select.h 33 * @brief Wait for events on a set of file descriptors. 34 * New code should prefer the different interface specified in <poll.h> instead, 35 * because it scales better and easily avoids the limits on `fd_set` size. 36 */ 37 38 #include <sys/cdefs.h> 39 #include <sys/types.h> 40 41 #include <linux/time.h> 42 #include <signal.h> 43 44 __BEGIN_DECLS 45 46 typedef unsigned long fd_mask; 47 48 /** 49 * The limit on the largest fd that can be used with type `fd_set`. 50 * You can allocate your own memory, 51 * but new code should prefer the different interface specified in <poll.h> instead, 52 * because it scales better and easily avoids the limits on `fd_set` size. 53 */ 54 #define FD_SETSIZE 1024 55 #define NFDBITS (8 * sizeof(fd_mask)) 56 57 /** 58 * The type of a file descriptor set. Limited to 1024 fds. 59 * The underlying system calls do not have this limit, 60 * and callers can allocate their own sets with calloc(). 61 * 62 * New code should prefer the different interface specified in <poll.h> instead, 63 * because it scales better and easily avoids the limits on `fd_set` size. 64 */ 65 typedef struct { 66 fd_mask fds_bits[FD_SETSIZE/NFDBITS]; 67 } fd_set; 68 69 #define __FDELT(fd) ((fd) / NFDBITS) 70 #define __FDMASK(fd) (1UL << ((fd) % NFDBITS)) 71 #define __FDS_BITS(type, set) (__BIONIC_CAST(static_cast, type, set)->fds_bits) 72 73 void __FD_CLR_chk(int, fd_set* _Nonnull , size_t); 74 void __FD_SET_chk(int, fd_set* _Nonnull, size_t); 75 int __FD_ISSET_chk(int, const fd_set* _Nonnull, size_t); 76 77 /** 78 * FD_CLR() with no bounds checking for users that allocated their own set. 79 * New code should prefer <poll.h> instead. 80 */ 81 #define __FD_CLR(fd, set) (__FDS_BITS(fd_set*, set)[__FDELT(fd)] &= ~__FDMASK(fd)) 82 83 /** 84 * FD_SET() with no bounds checking for users that allocated their own set. 85 * New code should prefer <poll.h> instead. 86 */ 87 #define __FD_SET(fd, set) (__FDS_BITS(fd_set*, set)[__FDELT(fd)] |= __FDMASK(fd)) 88 89 /** 90 * FD_ISSET() with no bounds checking for users that allocated their own set. 91 * New code should prefer <poll.h> instead. 92 */ 93 #define __FD_ISSET(fd, set) ((__FDS_BITS(const fd_set*, set)[__FDELT(fd)] & __FDMASK(fd)) != 0) 94 95 /** 96 * Removes all 1024 fds from the given set. 97 * Limited to fds under 1024. 98 * New code should prefer <poll.h> instead for this reason, 99 * rather than using memset() directly. 100 */ 101 #define FD_ZERO(set) __builtin_memset(set, 0, sizeof(*__BIONIC_CAST(static_cast, const fd_set*, set))) 102 103 /** 104 * Removes `fd` from the given set. 105 * Limited to fds under 1024. 106 * New code should prefer <poll.h> instead for this reason, 107 * rather than using __FD_CLR(). 108 */ 109 #define FD_CLR(fd, set) __FD_CLR_chk(fd, set, __bos(set)) 110 111 /** 112 * Adds `fd` to the given set. 113 * Limited to fds under 1024. 114 * New code should prefer <poll.h> instead for this reason, 115 * rather than using __FD_SET(). 116 */ 117 #define FD_SET(fd, set) __FD_SET_chk(fd, set, __bos(set)) 118 119 /** 120 * Tests whether `fd` is in the given set. 121 * Limited to fds under 1024. 122 * New code should prefer <poll.h> instead for this reason, 123 * rather than using __FD_ISSET(). 124 */ 125 #define FD_ISSET(fd, set) __FD_ISSET_chk(fd, set, __bos(set)) 126 127 /** 128 * [select(2)](https://man7.org/linux/man-pages/man2/select.2.html) waits on a 129 * set of file descriptors. 130 * 131 * New code should prefer poll() from <poll.h> instead, 132 * because it scales better and easily avoids the limits on `fd_set` size. 133 * 134 * Returns the number of ready file descriptors on success, 0 for timeout, 135 * and returns -1 and sets `errno` on failure. 136 */ 137 int select(int __max_fd_plus_one, fd_set* _Nullable __read_fds, fd_set* _Nullable __write_fds, fd_set* _Nullable __exception_fds, struct timeval* _Nullable __timeout); 138 139 /** 140 * [pselect(2)](https://man7.org/linux/man-pages/man2/pselect.2.html) waits on a 141 * set of file descriptors. 142 * 143 * New code should prefer ppoll() from <poll.h> instead, 144 * because it scales better and easily avoids the limits on `fd_set` size. 145 * 146 * Returns the number of ready file descriptors on success, 0 for timeout, 147 * and returns -1 and sets `errno` on failure. 148 */ 149 int pselect(int __max_fd_plus_one, fd_set* _Nullable __read_fds, fd_set* _Nullable __write_fds, fd_set* _Nullable __exception_fds, const struct timespec* _Nullable __timeout, const sigset_t* _Nullable __mask); 150 151 /** 152 * [pselect64(2)](https://man7.org/linux/man-pages/man2/select.2.html) waits on a 153 * set of file descriptors. 154 * 155 * New code should prefer ppoll64() from <poll.h> instead, 156 * because it scales better and easily avoids the limits on `fd_set` size. 157 * 158 * Returns the number of ready file descriptors on success, 0 for timeout, 159 * and returns -1 and sets `errno` on failure. 160 * 161 * Available since API level 28. 162 */ 163 #if __BIONIC_AVAILABILITY_GUARD(28) 164 int pselect64(int __max_fd_plus_one, fd_set* _Nullable __read_fds, fd_set* _Nullable __write_fds, fd_set* _Nullable __exception_fds, const struct timespec* _Nullable __timeout, const sigset64_t* _Nullable __mask) __INTRODUCED_IN(28); 165 #endif /* __BIONIC_AVAILABILITY_GUARD(28) */ 166 167 __END_DECLS 168