fake_epoll.h

   1 /* kludge up some limited epoll semantics using select for 2.4 kernels */
   2 /* $Id: fake_epoll.h,v 1.2 2007-06-28 07:22:50 bodea Exp $ */
   3
   4 #ifndef __FAKE_EPOLL_H__
   5 #define __FAKE_EPOLL_H__
   6
   7 #define EPOLLIN         0x01
   8 #define EPOLLOUT        0x04
   9 #define EPOLLERR        0x08
  10 #define EPOLLHUP        0x10
  11
  12 #define EPOLL_CTL_ADD   1
  13 #define EPOLL_CTL_DEL   2
  14 #define EPOLL_CTL_MOD   3
  15
  16 struct epoll_event {
  17     uint32_t events;
  18     union epoll_data {
  19         void *ptr;
  20         int fd;
  21         uint32_t u32;
  22         uint64_t u64;
  23     } data;
  24 };
  25
  26 int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event);
  27
  28 #ifdef FAKE_EPOLL_IMPLEMENTATION
  29
  30 #include <sys/select.h>
  31
  32 static fd_set _epoll_read_set;
  33 static fd_set _epoll_write_set;
  34 static int _epoll_fds;
  35 static struct epoll_event *_epoll_data[128];
  36
  37 static int epoll_create(int size __attribute__ ((unused)))
  38 {
  39     static int once = 0;
  40     if (once++)
  41     {
  42         errno = ENFILE; /* only support one instance */
  43         return -1;
  44     }
  45
  46     FD_ZERO(&_epoll_read_set);
  47     FD_ZERO(&_epoll_write_set);
  48     _epoll_fds = 0;
  49
  50     memset(_epoll_data, 0, sizeof(_epoll_data));
  51
  52     return 1; /* "descriptor" */
  53 }
  54
  55 int epoll_ctl(int epfd __attribute__ ((unused)), int op, int fd,
  56     struct epoll_event *event)
  57 {
  58     if (fd > (sizeof(_epoll_data)/sizeof(*_epoll_data)) - 1)
  59     {
  60         errno = EINVAL;
  61         return -1;
  62     }
  63
  64     switch (op)
  65     {
  66     case EPOLL_CTL_ADD:
  67         if (event->events & EPOLLIN)
  68             FD_SET(fd, &_epoll_read_set);
  69
  70         if (event->events & EPOLLOUT)
  71             FD_SET(fd, &_epoll_write_set);
  72
  73         if (fd >= _epoll_fds)
  74             _epoll_fds = fd + 1;
  75
  76         if (_epoll_data[fd])
  77             free(_epoll_data[fd]);
  78
  79         if (!(_epoll_data[fd] = malloc(sizeof(*_epoll_data))))
  80         {
  81             errno = ENOMEM;
  82             return -1;
  83         }
  84
  85         memcpy(_epoll_data[fd], &event->data, sizeof(*_epoll_data));
  86         break;
  87
  88     case EPOLL_CTL_MOD:
  89         if (event->events & EPOLLIN)
  90             FD_SET(fd, &_epoll_read_set);
  91         else
  92             FD_CLR(fd, &_epoll_read_set);
  93
  94         if (event->events & EPOLLOUT)
  95             FD_SET(fd, &_epoll_write_set);
  96         else
  97             FD_CLR(fd, &_epoll_write_set);
  98
  99         memcpy(_epoll_data[fd], &event->data, sizeof(*_epoll_data));
 100         break;
 101
 102     case EPOLL_CTL_DEL:
 103         FD_CLR(fd, &_epoll_read_set);
 104         FD_CLR(fd, &_epoll_write_set);
 105
 106         free(_epoll_data[fd]);
 107         _epoll_data[fd] = 0;
 108
 109         if (fd == _epoll_fds - 1)
 110         {
 111             _epoll_fds = 0;
 112             while (fd-- > 0)
 113             {
 114                 if (FD_ISSET(fd, &_epoll_read_set) ||
 115                     FD_ISSET(fd, &_epoll_write_set))
 116                 {
 117                     _epoll_fds = fd + 1;
 118                     break;
 119                 }
 120             }
 121         }
 122
 123         break;
 124     }
 125
 126     return 0;
 127 }
 128
 129 static int epoll_wait(int epfd __attribute__ ((unused)),
 130     struct epoll_event *events, int maxevents, int timout)
 131 {
 132     fd_set r;
 133     fd_set w;
 134     struct timeval t;
 135     struct timeval *tp;
 136     int n;
 137     int e;
 138     int i;
 139
 140     memcpy(&r, &_epoll_read_set, sizeof(r));
 141     memcpy(&w, &_epoll_write_set, sizeof(w));
 142
 143     if (timout >= 0)
 144     {
 145         t.tv_sec = 0;
 146         t.tv_usec = timout * 1000;
 147         tp = &t;
 148     }
 149     else
 150         tp = 0;
 151
 152     n = select(_epoll_fds, &r, &w, 0, tp);
 153     if (n < 0)
 154         return n;
 155
 156     if (n > maxevents)
 157         n = maxevents;
 158
 159     for (i = e = 0; n > 0 && i < _epoll_fds; i++)
 160     {
 161         if (!_epoll_data[i])
 162             continue;
 163
 164         events[e].events = 0;
 165         if (FD_ISSET(i, &r))
 166             events[e].events |= EPOLLIN;
 167
 168         if (FD_ISSET(i, &w))
 169             events[e].events |= EPOLLOUT;
 170
 171         if (events[e].events)
 172         {
 173             memcpy(&events[e++].data, _epoll_data[i], sizeof(events[0].data));
 174             n--;
 175         }
 176     }
 177
 178     return e;
 179 }
 180
 181 #endif /* FAKE_EPOLL_IMPLEMENTATION */
 182 #endif /* __FAKE_EPOLL_H__ */