/src/libev/ev_select.c

  1/*
  2 * libev select fd activity backend
  3 *
  4 * Copyright (c) 2007,2008,2009,2010 Marc Alexander Lehmann <libev@schmorp.de>
  5 * All rights reserved.
  6 *
  7 * Redistribution and use in source and binary forms, with or without modifica-
  8 * tion, are permitted provided that the following conditions are met:
  9 * 
 10 *   1.  Redistributions of source code must retain the above copyright notice,
 11 *       this list of conditions and the following disclaimer.
 12 * 
 13 *   2.  Redistributions in binary form must reproduce the above copyright
 14 *       notice, this list of conditions and the following disclaimer in the
 15 *       documentation and/or other materials provided with the distribution.
 16 * 
 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 18 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 19 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 20 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 21 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 22 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 23 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 24 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 25 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 26 * OF THE POSSIBILITY OF SUCH DAMAGE.
 27 *
 28 * Alternatively, the contents of this file may be used under the terms of
 29 * the GNU General Public License ("GPL") version 2 or any later version,
 30 * in which case the provisions of the GPL are applicable instead of
 31 * the above. If you wish to allow the use of your version of this file
 32 * only under the terms of the GPL and not to allow others to use your
 33 * version of this file under the BSD license, indicate your decision
 34 * by deleting the provisions above and replace them with the notice
 35 * and other provisions required by the GPL. If you do not delete the
 36 * provisions above, a recipient may use your version of this file under
 37 * either the BSD or the GPL.
 38 */
 39
 40#ifndef _WIN32
 41/* for unix systems */
 42# include <sys/select.h>
 43# include <inttypes.h>
 44#endif
 45
 46#ifndef EV_SELECT_USE_FD_SET
 47# ifdef NFDBITS
 48#  define EV_SELECT_USE_FD_SET 0
 49# else
 50#  define EV_SELECT_USE_FD_SET 1
 51# endif
 52#endif
 53
 54#if EV_SELECT_IS_WINSOCKET
 55# undef EV_SELECT_USE_FD_SET
 56# define EV_SELECT_USE_FD_SET 1
 57# undef NFDBITS
 58# define NFDBITS 0
 59#endif
 60
 61#if !EV_SELECT_USE_FD_SET
 62# define NFDBYTES (NFDBITS / 8)
 63#endif
 64
 65#include <string.h>
 66
 67static void
 68select_modify (EV_P_ int fd, int oev, int nev)
 69{
 70  if (oev == nev)
 71    return;
 72
 73  {
 74#if EV_SELECT_USE_FD_SET
 75
 76    #if EV_SELECT_IS_WINSOCKET
 77    SOCKET handle = anfds [fd].handle;
 78    #else
 79    int handle = fd;
 80    #endif
 81
 82    assert (("libev: fd >= FD_SETSIZE passed to fd_set-based select backend", fd < FD_SETSIZE));
 83
 84    /* FD_SET is broken on windows (it adds the fd to a set twice or more,
 85     * which eventually leads to overflows). Need to call it only on changes.
 86     */
 87    #if EV_SELECT_IS_WINSOCKET
 88    if ((oev ^ nev) & EV_READ)
 89    #endif
 90      if (nev & EV_READ)
 91        FD_SET (handle, (fd_set *)vec_ri);
 92      else
 93        FD_CLR (handle, (fd_set *)vec_ri);
 94
 95    #if EV_SELECT_IS_WINSOCKET
 96    if ((oev ^ nev) & EV_WRITE)
 97    #endif
 98      if (nev & EV_WRITE)
 99        FD_SET (handle, (fd_set *)vec_wi);
100      else
101        FD_CLR (handle, (fd_set *)vec_wi);
102
103#else
104
105    int     word = fd / NFDBITS;
106    fd_mask mask = 1UL << (fd % NFDBITS);
107
108    if (expect_false (vec_max <= word))
109      {
110        int new_max = word + 1;
111
112        vec_ri = ev_realloc (vec_ri, new_max * NFDBYTES);
113        vec_ro = ev_realloc (vec_ro, new_max * NFDBYTES); /* could free/malloc */
114        vec_wi = ev_realloc (vec_wi, new_max * NFDBYTES);
115        vec_wo = ev_realloc (vec_wo, new_max * NFDBYTES); /* could free/malloc */
116        #ifdef _WIN32
117        vec_eo = ev_realloc (vec_eo, new_max * NFDBYTES); /* could free/malloc */
118        #endif
119
120        for (; vec_max < new_max; ++vec_max)
121          ((fd_mask *)vec_ri) [vec_max] =
122          ((fd_mask *)vec_wi) [vec_max] = 0;
123      }
124
125    ((fd_mask *)vec_ri) [word] |= mask;
126    if (!(nev & EV_READ))
127      ((fd_mask *)vec_ri) [word] &= ~mask;
128
129    ((fd_mask *)vec_wi) [word] |= mask;
130    if (!(nev & EV_WRITE))
131      ((fd_mask *)vec_wi) [word] &= ~mask;
132#endif
133  }
134}
135
136static void
137select_poll (EV_P_ ev_tstamp timeout)
138{
139  struct timeval tv;
140  int res;
141  int fd_setsize;
142
143  EV_RELEASE_CB;
144  EV_TV_SET (tv, timeout);
145
146#if EV_SELECT_USE_FD_SET
147  fd_setsize = sizeof (fd_set);
148#else
149  fd_setsize = vec_max * NFDBYTES;
150#endif
151
152  memcpy (vec_ro, vec_ri, fd_setsize);
153  memcpy (vec_wo, vec_wi, fd_setsize);
154
155#ifdef _WIN32
156  /* pass in the write set as except set.
157   * the idea behind this is to work around a windows bug that causes
158   * errors to be reported as an exception and not by setting
159   * the writable bit. this is so uncontrollably lame.
160   */
161  memcpy (vec_eo, vec_wi, fd_setsize);
162  res = select (vec_max * NFDBITS, (fd_set *)vec_ro, (fd_set *)vec_wo, (fd_set *)vec_eo, &tv);
163#elif EV_SELECT_USE_FD_SET
164  fd_setsize = anfdmax < FD_SETSIZE ? anfdmax : FD_SETSIZE;
165  res = select (fd_setsize, (fd_set *)vec_ro, (fd_set *)vec_wo, 0, &tv);
166#else
167  res = select (vec_max * NFDBITS, (fd_set *)vec_ro, (fd_set *)vec_wo, 0, &tv);
168#endif
169  EV_ACQUIRE_CB;
170
171  if (expect_false (res < 0))
172    {
173      #if EV_SELECT_IS_WINSOCKET
174      errno = WSAGetLastError ();
175      #endif
176      #ifdef WSABASEERR
177      /* on windows, select returns incompatible error codes, fix this */
178      if (errno >= WSABASEERR && errno < WSABASEERR + 1000)
179        if (errno == WSAENOTSOCK)
180          errno = EBADF;
181        else
182          errno -= WSABASEERR;
183      #endif
184
185      #ifdef _WIN32
186      /* select on windows erroneously returns EINVAL when no fd sets have been
187       * provided (this is documented). what microsoft doesn't tell you that this bug
188       * exists even when the fd sets _are_ provided, so we have to check for this bug
189       * here and emulate by sleeping manually.
190       * we also get EINVAL when the timeout is invalid, but we ignore this case here
191       * and assume that EINVAL always means: you have to wait manually.
192       */
193      if (errno == EINVAL)
194        {
195          ev_sleep (timeout);
196          return;
197        }
198      #endif
199
200      if (errno == EBADF)
201        fd_ebadf (EV_A);
202      else if (errno == ENOMEM && !syserr_cb)
203        fd_enomem (EV_A);
204      else if (errno != EINTR)
205        ev_syserr ("(libev) select");
206
207      return;
208    }
209
210#if EV_SELECT_USE_FD_SET
211
212  {
213    int fd;
214
215    for (fd = 0; fd < anfdmax; ++fd)
216      if (anfds [fd].events)
217        {
218          int events = 0;
219          #if EV_SELECT_IS_WINSOCKET
220          SOCKET handle = anfds [fd].handle;
221          #else
222          int handle = fd;
223          #endif
224
225          if (FD_ISSET (handle, (fd_set *)vec_ro)) events |= EV_READ;
226          if (FD_ISSET (handle, (fd_set *)vec_wo)) events |= EV_WRITE;
227          #ifdef _WIN32
228          if (FD_ISSET (handle, (fd_set *)vec_eo)) events |= EV_WRITE;
229          #endif
230
231          if (expect_true (events))
232            fd_event (EV_A_ fd, events);
233        }
234  }
235
236#else
237
238  {
239    int word, bit;
240    for (word = vec_max; word--; )
241      {
242        fd_mask word_r = ((fd_mask *)vec_ro) [word];
243        fd_mask word_w = ((fd_mask *)vec_wo) [word];
244        #ifdef _WIN32
245        word_w |= ((fd_mask *)vec_eo) [word];
246        #endif
247
248        if (word_r || word_w)
249          for (bit = NFDBITS; bit--; )
250            {
251              fd_mask mask = 1UL << bit;
252              int events = 0;
253
254              events |= word_r & mask ? EV_READ  : 0;
255              events |= word_w & mask ? EV_WRITE : 0;
256
257              if (expect_true (events))
258                fd_event (EV_A_ word * NFDBITS + bit, events);
259            }
260      }
261  }
262
263#endif
264}
265
266int inline_size
267select_init (EV_P_ int flags)
268{
269  backend_fudge  = 0.; /* posix says this is zero */
270  backend_modify = select_modify;
271  backend_poll   = select_poll;
272
273#if EV_SELECT_USE_FD_SET
274  vec_ri  = ev_malloc (sizeof (fd_set)); FD_ZERO ((fd_set *)vec_ri);
275  vec_ro  = ev_malloc (sizeof (fd_set));
276  vec_wi  = ev_malloc (sizeof (fd_set)); FD_ZERO ((fd_set *)vec_wi);
277  vec_wo  = ev_malloc (sizeof (fd_set));
278  #ifdef _WIN32
279  vec_eo  = ev_malloc (sizeof (fd_set));
280  #endif
281#else
282  vec_max = 0;
283  vec_ri  = 0; 
284  vec_ro  = 0;   
285  vec_wi  = 0; 
286  vec_wo  = 0; 
287  #ifdef _WIN32
288  vec_eo  = 0;
289  #endif
290#endif
291
292  return EVBACKEND_SELECT;
293}
294
295void inline_size
296select_destroy (EV_P)
297{
298  ev_free (vec_ri);
299  ev_free (vec_ro);
300  ev_free (vec_wi);
301  ev_free (vec_wo);
302  #ifdef _WIN32
303  ev_free (vec_eo);
304  #endif
305}
306
307