“sys/epoll.h”代碼

推薦閱讀“sys/epoll.h”代碼，有助於理解epoll函數的用法。
Browse the source code of glibc/sysdeps/unix/sysv/linux/sys/epoll.h

/* Copyright (C) 2002-2019 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.
   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.
   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */
#ifndef        _SYS_EPOLL_H
#define        _SYS_EPOLL_H        1
#include <stdint.h>
#include <sys/types.h>
#include <bits/types/sigset_t.h>
/* Get the platform-dependent flags.  */
#include <bits/epoll.h>
#ifndef __EPOLL_PACKED
# define __EPOLL_PACKED
#endif
enum EPOLL_EVENTS
  {
    EPOLLIN = 0x001,
#define EPOLLIN EPOLLIN
    EPOLLPRI = 0x002,
#define EPOLLPRI EPOLLPRI
    EPOLLOUT = 0x004,
#define EPOLLOUT EPOLLOUT
    EPOLLRDNORM = 0x040,
#define EPOLLRDNORM EPOLLRDNORM
    EPOLLRDBAND = 0x080,
#define EPOLLRDBAND EPOLLRDBAND
    EPOLLWRNORM = 0x100,
#define EPOLLWRNORM EPOLLWRNORM
    EPOLLWRBAND = 0x200,
#define EPOLLWRBAND EPOLLWRBAND
    EPOLLMSG = 0x400,
#define EPOLLMSG EPOLLMSG
    EPOLLERR = 0x008,
#define EPOLLERR EPOLLERR
    EPOLLHUP = 0x010,
#define EPOLLHUP EPOLLHUP
    EPOLLRDHUP = 0x2000,
#define EPOLLRDHUP EPOLLRDHUP
    EPOLLEXCLUSIVE = 1u << 28,
#define EPOLLEXCLUSIVE EPOLLEXCLUSIVE
    EPOLLWAKEUP = 1u << 29,
#define EPOLLWAKEUP EPOLLWAKEUP
    EPOLLONESHOT = 1u << 30,
#define EPOLLONESHOT EPOLLONESHOT
    EPOLLET = 1u << 31
#define EPOLLET EPOLLET
  };
/* Valid opcodes ( "op" parameter ) to issue to epoll_ctl().  */
#define EPOLL_CTL_ADD 1        /* Add a file descriptor to the interface.  */
#define EPOLL_CTL_DEL 2        /* Remove a file descriptor from the interface.  */
#define EPOLL_CTL_MOD 3        /* Change file descriptor epoll_event structure.  */
typedef union epoll_data
{
  void *ptr;
  int fd;
  uint32_t u32;
  uint64_t u64;
} epoll_data_t;
struct epoll_event
{
  uint32_t events;        /* Epoll events */
  epoll_data_t data;        /* User data variable */
} __EPOLL_PACKED;
__BEGIN_DECLS
/* Creates an epoll instance.  Returns an fd for the new instance.
   The "size" parameter is a hint specifying the number of file
   descriptors to be associated with the new instance.  The fd
   returned by epoll_create() should be closed with close().  */
extern int epoll_create (int __size) __THROW;
/* Same as epoll_create but with an FLAGS parameter.  The unused SIZE
   parameter has been dropped.  */
extern int epoll_create1 (int __flags) __THROW;
/* Manipulate an epoll instance "epfd". Returns 0 in case of success,
   -1 in case of error ( the "errno" variable will contain the
   specific error code ) The "op" parameter is one of the EPOLL_CTL_*
   constants defined above. The "fd" parameter is the target of the
   operation. The "event" parameter describes which events the caller
   is interested in and any associated user data.  */
extern int epoll_ctl (int __epfd, int __op, int __fd,
                      struct epoll_event *__event) __THROW;
/* Wait for events on an epoll instance "epfd". Returns the number of
   triggered events returned in "events" buffer. Or -1 in case of
   error with the "errno" variable set to the specific error code. The
   "events" parameter is a buffer that will contain triggered
   events. The "maxevents" is the maximum number of events to be
   returned ( usually size of "events" ). The "timeout" parameter
   specifies the maximum wait time in milliseconds (-1 == infinite).
   This function is a cancellation point and therefore not marked with
   __THROW.  */
extern int epoll_wait (int __epfd, struct epoll_event *__events,
                       int __maxevents, int __timeout);
/* Same as epoll_wait, but the thread's signal mask is temporarily
   and atomically replaced with the one provided as parameter.
   This function is a cancellation point and therefore not marked with
   __THROW.  */
extern int epoll_pwait (int __epfd, struct epoll_event *__events,
                        int __maxevents, int __timeout,
                        const __sigset_t *__ss);
__END_DECLS
#endif /* sys/epoll.h */

注：上述代碼的出處：https://code.woboq.org/userspace/glibc/sysdeps/unix/sysv/linux/sys/epoll.h.html

附錄

linux內核的eventepoll.c文件所在的目錄是“linux/fs/eventpoll.c”。GitHub地址如下：
https://github.com/lozhibo/linux/blob/master/fs/eventpoll.c
如有興趣，可參考網上剖析epoll源代碼的文章學習。