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/eventfd.h 33 * @brief Event notification file descriptors. 34 */ 35 36 #include <sys/cdefs.h> 37 #include <fcntl.h> 38 #include <linux/eventfd.h> 39 40 __BEGIN_DECLS 41 42 /*! \macro EFD_SEMAPHORE 43 * The eventfd() flag to provide semaphore-like semantics for reads. 44 */ 45 /*! \macro EFD_CLOEXEC 46 * The eventfd() flag for a close-on-exec file descriptor. 47 */ 48 /*! \macro EFD_NONBLOCK 49 * The eventfd() flag for a non-blocking file descriptor. 50 */ 51 52 /** 53 * [eventfd(2)](https://man7.org/linux/man-pages/man2/eventfd.2.html) creates a file descriptor 54 * for event notification. 55 * 56 * Returns a new file descriptor on success, and returns -1 and sets `errno` on failure. 57 */ 58 int eventfd(unsigned int __initial_value, int __flags); 59 60 /** The type used by eventfd_read() and eventfd_write(). */ 61 typedef uint64_t eventfd_t; 62 63 /** 64 * [eventfd_read(3)](https://man7.org/linux/man-pages/man2/eventfd.2.html) is a convenience 65 * wrapper to read an `eventfd_t` from an eventfd file descriptor. 66 * 67 * Returns 0 on success, or returns -1 otherwise. 68 */ 69 int eventfd_read(int __fd, eventfd_t* _Nonnull __value); 70 71 /** 72 * [eventfd_write(3)](https://man7.org/linux/man-pages/man2/eventfd.2.html) is a convenience 73 * wrapper to write an `eventfd_t` to an eventfd file descriptor. 74 * 75 * Returns 0 on success, or returns -1 otherwise. 76 */ 77 int eventfd_write(int __fd, eventfd_t __value); 78 79 __END_DECLS 80