libc/winsup/cygwin/poll.cc

/* poll.cc. Implements poll(2) via usage of select(2) call.

   Copyright 2000, 2001 Red Hat, Inc.

   This file is part of Cygwin.

   This software is a copyrighted work licensed under the terms of the
   Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
   details. */

#include "winsup.h"
#include <sys/time.h>
#include <sys/poll.h>
#include <errno.h>
#include <stdlib.h>
#include "security.h"
#include "fhandler.h"
#include "path.h"
#include "dtable.h"
#include "cygerrno.h"
#include "cygheap.h"
#include "sigproc.h"

extern "C"
int
poll (struct pollfd *fds, unsigned int nfds, int timeout)
{
  int max_fd = 0;
  fd_set *read_fds, *write_fds, *except_fds;
  struct timeval tv = { timeout / 1000, (timeout % 1000) * 1000 };
  sigframe thisframe (mainthread);

  for (unsigned int i = 0; i < nfds; ++i)
    if (fds[i].fd > max_fd)
      max_fd = fds[i].fd;

  size_t fds_size = howmany(max_fd + 1, NFDBITS) * sizeof (fd_mask);

  read_fds = (fd_set *) alloca (fds_size);
  write_fds = (fd_set *) alloca (fds_size);
  except_fds = (fd_set *) alloca (fds_size);

  if (!read_fds || !write_fds || !except_fds)
    {
      set_errno (ENOMEM);
      return -1;
    }

  memset (read_fds, 0, fds_size);
  memset (write_fds, 0, fds_size);
  memset (except_fds, 0, fds_size);

  for (unsigned int i = 0; i < nfds; ++i) 
    { 
      fds[i].revents = 0; 
      if (!cygheap->fdtab.not_open(fds[i].fd)) 
	{ 
	  if (fds[i].events & POLLIN) 
	    FD_SET(fds[i].fd, read_fds); 
	  if (fds[i].events & POLLOUT) 
	    FD_SET(fds[i].fd, write_fds); 
	  if (fds[i].events & POLLPRI) 
	    FD_SET(fds[i].fd, except_fds); 
	} 
    } 

  int ret = cygwin_select (max_fd + 1, read_fds, write_fds, except_fds, timeout < 0 ? NULL : &tv);

  if (ret > 0) 
    for (unsigned int i = 0; i < nfds; ++i) 
      { 
	if (fds[i].fd < 0) 
	  fds[i].revents = POLLNVAL; 
	else if (cygheap->fdtab.not_open(fds[i].fd)) 
	  fds[i].revents = POLLHUP; 
	else 
	  { 
	    if (FD_ISSET(fds[i].fd, read_fds)) 
	      fds[i].revents |= POLLIN; 
	    if (FD_ISSET(fds[i].fd, write_fds)) 
	      fds[i].revents |= POLLOUT; 
	    if (FD_ISSET(fds[i].fd, read_fds) && FD_ISSET(fds[i].fd, write_fds)) 
	      fds[i].revents |= POLLERR; 
	    if (FD_ISSET(fds[i].fd, except_fds)) 
	      fds[i].revents |= POLLPRI; 
	  } 
      } 

  return ret; 
}