src/xgselect.c

   1 /* Function for handling the GLib event loop.
   2
   3 Copyright (C) 2009-2013 Free Software Foundation, Inc.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software: you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation, either version 3 of the License, or
  10 (at your option) any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include <config.h>
  21
  22 #include "xgselect.h"
  23
  24 #ifdef HAVE_GLIB
  25
  26 #include <glib.h>
  27 #include <errno.h>
  28 #include "frame.h"
  29
  30 int
  31 xg_select (int fds_lim, SELECT_TYPE *rfds, SELECT_TYPE *wfds, SELECT_TYPE *efds,
  32            EMACS_TIME *timeout, sigset_t *sigmask)
  33 {
  34   SELECT_TYPE all_rfds, all_wfds;
  35   EMACS_TIME tmo, *tmop = timeout;
  36
  37   GMainContext *context;
  38   int have_wfds = wfds != NULL;
  39   GPollFD gfds_buf[128];
  40   GPollFD *gfds = gfds_buf;
  41   int gfds_size = sizeof gfds_buf / sizeof *gfds_buf;
  42   int n_gfds, retval = 0, our_fds = 0, max_fds = fds_lim - 1;
  43   int i, nfds, tmo_in_millisec;
  44   USE_SAFE_ALLOCA;
  45
  46   /* Do not try to optimize with an initial check with g_main_context_pending
  47      and a call to pselect if it returns false.  If Gdk has a timeout for 0.01
  48      second, and Emacs has a timeout for 1 second, g_main_context_pending will
  49      return false, but the timeout will be 1 second, thus missing the gdk
  50      timeout with a lot.  */
  51
  52   context = g_main_context_default ();
  53
  54   if (rfds) all_rfds = *rfds;
  55   else FD_ZERO (&all_rfds);
  56   if (wfds) all_wfds = *wfds;
  57   else FD_ZERO (&all_wfds);
  58
  59   n_gfds = g_main_context_query (context, G_PRIORITY_LOW, &tmo_in_millisec,
  60                                  gfds, gfds_size);
  61   if (gfds_size < n_gfds)
  62     {
  63       SAFE_NALLOCA (gfds, sizeof *gfds, n_gfds);
  64       gfds_size = n_gfds;
  65       n_gfds = g_main_context_query (context, G_PRIORITY_LOW, &tmo_in_millisec,
  66                                      gfds, gfds_size);
  67     }
  68
  69   for (i = 0; i < n_gfds; ++i)
  70     {
  71       if (gfds[i].events & G_IO_IN)
  72         {
  73           FD_SET (gfds[i].fd, &all_rfds);
  74           if (gfds[i].fd > max_fds) max_fds = gfds[i].fd;
  75         }
  76       if (gfds[i].events & G_IO_OUT)
  77         {
  78           FD_SET (gfds[i].fd, &all_wfds);
  79           if (gfds[i].fd > max_fds) max_fds = gfds[i].fd;
  80           have_wfds = 1;
  81         }
  82     }
  83
  84   SAFE_FREE ();
  85
  86   if (tmo_in_millisec >= 0)
  87     {
  88       tmo = make_emacs_time (tmo_in_millisec / 1000,
  89                              1000 * 1000 * (tmo_in_millisec % 1000));
  90       if (!timeout || EMACS_TIME_LT (tmo, *timeout))
  91         tmop = &tmo;
  92     }
  93
  94   fds_lim = max_fds + 1;
  95   nfds = pselect (fds_lim, &all_rfds, have_wfds ? &all_wfds : NULL,
  96                   efds, tmop, sigmask);
  97
  98   if (nfds < 0)
  99     retval = nfds;
 100   else if (nfds > 0)
 101     {
 102       for (i = 0; i < fds_lim; ++i)
 103         {
 104           if (FD_ISSET (i, &all_rfds))
 105             {
 106               if (rfds && FD_ISSET (i, rfds)) ++retval;
 107               else ++our_fds;
 108             }
 109           else if (rfds)
 110             FD_CLR (i, rfds);
 111
 112           if (have_wfds && FD_ISSET (i, &all_wfds))
 113             {
 114               if (wfds && FD_ISSET (i, wfds)) ++retval;
 115               else ++our_fds;
 116             }
 117           else if (wfds)
 118             FD_CLR (i, wfds);
 119
 120           if (efds && FD_ISSET (i, efds))
 121             ++retval;
 122         }
 123     }
 124
 125   if (our_fds > 0 || (nfds == 0 && tmop == &tmo))
 126     {
 127
 128       /* If Gtk+ is in use eventually gtk_main_iteration will be called,
 129          unless retval is zero.  */
 130 #ifdef USE_GTK
 131       if (retval == 0)
 132 #endif
 133         while (g_main_context_pending (context))
 134           g_main_context_dispatch (context);
 135
 136       /* To not have to recalculate timeout, return like this.  */
 137       if (retval == 0)
 138         {
 139           retval = -1;
 140           errno = EINTR;
 141         }
 142     }
 143
 144   return retval;
 145 }
 146 #endif /* HAVE_GLIB */