CSE2410 Fall 2014 Bounce

/*

 * libev select fd activity backend

 *

 * Copyright (c) 2007,2008,2009 Marc Alexander Lehmann <libev@schmorp.de>

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without modifica-

 * tion, are permitted provided that the following conditions are met:

 * 

 *   1.  Redistributions of source code must retain the above copyright notice,

 *       this list of conditions and the following disclaimer.

 * 

 *   2.  Redistributions in binary form must reproduce the above copyright

 *       notice, this list of conditions and the following disclaimer in the

 *       documentation and/or other materials provided with the distribution.

 * 

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED

 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-

 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO

 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-

 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;

 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-

 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

 * OF THE POSSIBILITY OF SUCH DAMAGE.

 *

 * Alternatively, the contents of this file may be used under the terms of

 * the GNU General Public License ("GPL") version 2 or any later version,

 * in which case the provisions of the GPL are applicable instead of

 * the above. If you wish to allow the use of your version of this file

 * only under the terms of the GPL and not to allow others to use your

 * version of this file under the BSD license, indicate your decision

 * by deleting the provisions above and replace them with the notice

 * and other provisions required by the GPL. If you do not delete the

 * provisions above, a recipient may use your version of this file under

 * either the BSD or the GPL.

 */

#ifndef _WIN32

/* for unix systems */

# include <sys/select.h>

# include <inttypes.h>

#endif

#ifndef EV_SELECT_USE_FD_SET

# ifdef NFDBITS

#  define EV_SELECT_USE_FD_SET 0

# else

#  define EV_SELECT_USE_FD_SET 1

# endif

#endif

#if EV_SELECT_IS_WINSOCKET

# undef EV_SELECT_USE_FD_SET

# define EV_SELECT_USE_FD_SET 1

# undef NFDBITS

# define NFDBITS 0

#endif

#if !EV_SELECT_USE_FD_SET

# define NFDBYTES (NFDBITS / 8)

#endif

#include <string.h>

static void

select_modify (EV_P_ int fd, int oev, int nev)

{

  if (oev == nev)

    return;

  {

#if EV_SELECT_USE_FD_SET

    #if EV_SELECT_IS_WINSOCKET

    SOCKET handle = anfds [fd].handle;

    #else

    int handle = fd;

    #endif

    assert (("libev: fd >= FD_SETSIZE passed to fd_set-based select backend", fd < FD_SETSIZE));

    /* FD_SET is broken on windows (it adds the fd to a set twice or more,

     * which eventually leads to overflows). Need to call it only on changes.

     */

    #if EV_SELECT_IS_WINSOCKET

    if ((oev ^ nev) & EV_READ)

    #endif

      if (nev & EV_READ)

        FD_SET (handle, (fd_set *)vec_ri);

      else

        FD_CLR (handle, (fd_set *)vec_ri);

    #if EV_SELECT_IS_WINSOCKET

    if ((oev ^ nev) & EV_WRITE)

    #endif

      if (nev & EV_WRITE)

        FD_SET (handle, (fd_set *)vec_wi);

      else

        FD_CLR (handle, (fd_set *)vec_wi);

#else

    int     word = fd / NFDBITS;

    fd_mask mask = 1UL << (fd % NFDBITS);

    if (expect_false (vec_max <= word))

      {

        int new_max = word + 1;

        vec_ri = ev_realloc (vec_ri, new_max * NFDBYTES);

        vec_ro = ev_realloc (vec_ro, new_max * NFDBYTES); /* could free/malloc */

        vec_wi = ev_realloc (vec_wi, new_max * NFDBYTES);

        vec_wo = ev_realloc (vec_wo, new_max * NFDBYTES); /* could free/malloc */

        #ifdef _WIN32

        vec_eo = ev_realloc (vec_eo, new_max * NFDBYTES); /* could free/malloc */

        #endif

        for (; vec_max < new_max; ++vec_max)

          ((fd_mask *)vec_ri) [vec_max] =

          ((fd_mask *)vec_wi) [vec_max] = 0;

      }

    ((fd_mask *)vec_ri) [word] |= mask;

    if (!(nev & EV_READ))

      ((fd_mask *)vec_ri) [word] &= ~mask;

    ((fd_mask *)vec_wi) [word] |= mask;

    if (!(nev & EV_WRITE))

      ((fd_mask *)vec_wi) [word] &= ~mask;

#endif

  }

}

static void

select_poll (EV_P_ ev_tstamp timeout)

{

  struct timeval tv;

  int res;

  int fd_setsize;

  tv.tv_sec  = (long)timeout;

  tv.tv_usec = (long)((timeout - (ev_tstamp)tv.tv_sec) * 1e6);

#if EV_SELECT_USE_FD_SET

  fd_setsize = sizeof (fd_set);

#else

  fd_setsize = vec_max * NFDBYTES;

#endif

  memcpy (vec_ro, vec_ri, fd_setsize);

  memcpy (vec_wo, vec_wi, fd_setsize);

#ifdef _WIN32

  /* pass in the write set as except set.

   * the idea behind this is to work around a windows bug that causes

   * errors to be reported as an exception and not by setting

   * the writable bit. this is so uncontrollably lame.

   */

  memcpy (vec_eo, vec_wi, fd_setsize);

  res = select (vec_max * NFDBITS, (fd_set *)vec_ro, (fd_set *)vec_wo, (fd_set *)vec_eo, &tv);

#elif EV_SELECT_USE_FD_SET

  fd_setsize = anfdmax < FD_SETSIZE ? anfdmax : FD_SETSIZE;

  res = select (fd_setsize, (fd_set *)vec_ro, (fd_set *)vec_wo, 0, &tv);

#else

  res = select (vec_max * NFDBITS, (fd_set *)vec_ro, (fd_set *)vec_wo, 0, &tv);

#endif

  if (expect_false (res < 0))

    {

      #if EV_SELECT_IS_WINSOCKET

      errno = WSAGetLastError ();

      #endif

      #ifdef WSABASEERR

      /* on windows, select returns incompatible error codes, fix this */

      if (errno >= WSABASEERR && errno < WSABASEERR + 1000)

        if (errno == WSAENOTSOCK)

          errno = EBADF;

        else

          errno -= WSABASEERR;

      #endif

      #ifdef _WIN32

      /* select on windows errornously returns EINVAL when no fd sets have been

       * provided (this is documented). what microsoft doesn't tell you that this bug

       * exists even when the fd sets _are_ provided, so we have to check for this bug

       * here and emulate by sleeping manually.

       * we also get EINVAL when the timeout is invalid, but we ignore this case here

       * and assume that EINVAL always means: you have to wait manually.

       */

      if (errno == EINVAL)

        {

          ev_sleep (timeout);

          return;

        }

      #endif

      if (errno == EBADF)

        fd_ebadf (EV_A);

      else if (errno == ENOMEM && !syserr_cb)

        fd_enomem (EV_A);

      else if (errno != EINTR)

        ev_syserr ("(libev) select");

      return;

    }

#if EV_SELECT_USE_FD_SET

  {

    int fd;

    for (fd = 0; fd < anfdmax; ++fd)

      if (anfds [fd].events)

        {

          int events = 0;

          #if EV_SELECT_IS_WINSOCKET

          SOCKET handle = anfds [fd].handle;

          #else

          int handle = fd;

          #endif

          if (FD_ISSET (handle, (fd_set *)vec_ro)) events |= EV_READ;

          if (FD_ISSET (handle, (fd_set *)vec_wo)) events |= EV_WRITE;

          #ifdef _WIN32

          if (FD_ISSET (handle, (fd_set *)vec_eo)) events |= EV_WRITE;

          #endif

          if (expect_true (events))

            fd_event (EV_A_ fd, events);

        }

  }

#else

  {

    int word, bit;

    for (word = vec_max; word--; )

      {

        fd_mask word_r = ((fd_mask *)vec_ro) [word];

        fd_mask word_w = ((fd_mask *)vec_wo) [word];

        #ifdef _WIN32

        word_w |= ((fd_mask *)vec_eo) [word];

        #endif

        if (word_r || word_w)

          for (bit = NFDBITS; bit--; )

            {

              fd_mask mask = 1UL << bit;

              int events = 0;

              events |= word_r & mask ? EV_READ  : 0;

              events |= word_w & mask ? EV_WRITE : 0;

              if (expect_true (events))

                fd_event (EV_A_ word * NFDBITS + bit, events);

            }

      }

  }

#endif

}

int inline_size

select_init (EV_P_ int flags)

{

  backend_fudge  = 0.; /* posix says this is zero */

  backend_modify = select_modify;

  backend_poll   = select_poll;

#if EV_SELECT_USE_FD_SET

  vec_ri  = ev_malloc (sizeof (fd_set)); FD_ZERO ((fd_set *)vec_ri);

  vec_ro  = ev_malloc (sizeof (fd_set));

  vec_wi  = ev_malloc (sizeof (fd_set)); FD_ZERO ((fd_set *)vec_wi);

  vec_wo  = ev_malloc (sizeof (fd_set));

  #ifdef _WIN32

  vec_eo  = ev_malloc (sizeof (fd_set));

  #endif

#else

  vec_max = 0;

  vec_ri  = 0; 

  vec_ri  = 0;   

  vec_wo  = 0; 

  vec_wo  = 0; 

#endif

  return EVBACKEND_SELECT;

}

void inline_size

select_destroy (EV_P)

{

  ev_free (vec_ri);

  ev_free (vec_ro);

  ev_free (vec_wi);

  ev_free (vec_wo);

}