winsup/cygwin/poll.cc

   1 /* poll.cc. Implements poll(2) via usage of select(2) call.
   2
   3    Copyright 2000, 2001, 2002 Red Hat, Inc.
   4
   5    This file is part of Cygwin.
   6
   7    This software is a copyrighted work licensed under the terms of the
   8    Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
   9    details. */
  10
  11 #include "winsup.h"
  12 #include <sys/time.h>
  13 #include <sys/poll.h>
  14 #include <sys/socket.h>
  15 #include <errno.h>
  16 #include <stdlib.h>
  17 #include "security.h"
  18 #include "fhandler.h"
  19 #include "path.h"
  20 #include "dtable.h"
  21 #include "cygerrno.h"
  22 #include "cygheap.h"
  23 #include "sigproc.h"
  24
  25 extern "C"
  26 int
  27 poll (struct pollfd *fds, unsigned int nfds, int timeout)
  28 {
  29   int max_fd = 0;
  30   fd_set *read_fds, *write_fds, *except_fds;
  31   struct timeval tv = { timeout / 1000, (timeout % 1000) * 1000 };
  32   sigframe thisframe (mainthread);
  33
  34   for (unsigned int i = 0; i < nfds; ++i)
  35     if (fds[i].fd > max_fd)
  36       max_fd = fds[i].fd;
  37
  38   size_t fds_size = howmany (max_fd + 1, NFDBITS) * sizeof (fd_mask);
  39
  40   read_fds = (fd_set *) alloca (fds_size);
  41   write_fds = (fd_set *) alloca (fds_size);
  42   except_fds = (fd_set *) alloca (fds_size);
  43
  44   if (!read_fds || !write_fds || !except_fds)
  45     {
  46       set_errno (ENOMEM);
  47       return -1;
  48     }
  49
  50   memset (read_fds, 0, fds_size);
  51   memset (write_fds, 0, fds_size);
  52   memset (except_fds, 0, fds_size);
  53
  54   int invalid_fds = 0;
  55   for (unsigned int i = 0; i < nfds; ++i)
  56     {
  57       fds[i].revents = 0;
  58       if (!cygheap->fdtab.not_open (fds[i].fd))
  59         {
  60           if (fds[i].events & POLLIN)
  61             FD_SET(fds[i].fd, read_fds);
  62           if (fds[i].events & POLLOUT)
  63             FD_SET(fds[i].fd, write_fds);
  64           if (fds[i].events & POLLPRI)
  65             FD_SET(fds[i].fd, except_fds);
  66         }
  67       else if (fds[i].fd >= 0)
  68         {
  69           ++invalid_fds;
  70           fds[i].revents = POLLNVAL;
  71         }
  72     }
  73
  74   if (invalid_fds)
  75     return invalid_fds;
  76
  77   int ret = cygwin_select (max_fd + 1, read_fds, write_fds, except_fds, timeout < 0 ? NULL : &tv);
  78
  79   if (ret > 0)
  80     for (unsigned int i = 0; i < nfds; ++i)
  81       {
  82         if (fds[i].fd >= 0)
  83           {
  84             if (cygheap->fdtab.not_open (fds[i].fd))
  85               fds[i].revents = POLLHUP;
  86             else
  87               {
  88                 if (FD_ISSET(fds[i].fd, read_fds))
  89                   {
  90                     char peek[1];
  91                     fhandler_socket *sock =
  92                                       cygheap->fdtab[fds[i].fd]->is_socket ();
  93                     if (!sock)
  94                       fds[i].revents |= POLLIN;
  95                     else
  96                       switch (sock->recvfrom (peek, sizeof (peek), MSG_PEEK,
  97                                               NULL, NULL))
  98                         {
  99                           case -1: /* Something weird happened */
 100                             fds[i].revents |= POLLERR;
 101                             break;
 102                           case 0:  /* Closed on the read side. */
 103                             fds[i].revents |= POLLHUP;
 104                             break;
 105                           default:
 106                             fds[i].revents |= POLLIN;
 107                             break;
 108                         }
 109                   }
 110                 if (FD_ISSET(fds[i].fd, write_fds))
 111                   fds[i].revents |= POLLOUT;
 112                 if (FD_ISSET(fds[i].fd, except_fds))
 113                   fds[i].revents |= POLLPRI;
 114               }
 115           }
 116       }
 117
 118   return ret;
 119 }