src/xgselect.c

   1 /* Function for handling the GLib event loop.
   2
   3 Copyright (C) 2009-2014 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 <stdbool.h>
  29 #include <timespec.h>
  30 #include "frame.h"
  31
  32 int
  33 xg_select (int fds_lim, fd_set *rfds, fd_set *wfds, fd_set *efds,
  34            struct timespec const *timeout, sigset_t const *sigmask)
  35 {
  36   fd_set all_rfds, all_wfds;
  37   struct timespec tmo;
  38   struct timespec const *tmop = timeout;
  39
  40   GMainContext *context;
  41   int have_wfds = wfds != NULL;
  42   GPollFD gfds_buf[128];
  43   GPollFD *gfds = gfds_buf;
  44   int gfds_size = ARRAYELTS (gfds_buf);
  45   int n_gfds, retval = 0, our_fds = 0, max_fds = fds_lim - 1;
  46   int i, nfds, tmo_in_millisec;
  47   bool need_to_dispatch;
  48   USE_SAFE_ALLOCA;
  49
  50   /* Do not try to optimize with an initial check with g_main_context_pending
  51      and a call to pselect if it returns false.  If Gdk has a timeout for 0.01
  52      second, and Emacs has a timeout for 1 second, g_main_context_pending will
  53      return false, but the timeout will be 1 second, thus missing the gdk
  54      timeout with a lot.  */
  55
  56   context = g_main_context_default ();
  57
  58   if (rfds) all_rfds = *rfds;
  59   else FD_ZERO (&all_rfds);
  60   if (wfds) all_wfds = *wfds;
  61   else FD_ZERO (&all_wfds);
  62
  63   n_gfds = g_main_context_query (context, G_PRIORITY_LOW, &tmo_in_millisec,
  64                                  gfds, gfds_size);
  65   if (gfds_size < n_gfds)
  66     {
  67       SAFE_NALLOCA (gfds, sizeof *gfds, n_gfds);
  68       gfds_size = n_gfds;
  69       n_gfds = g_main_context_query (context, G_PRIORITY_LOW, &tmo_in_millisec,
  70                                      gfds, gfds_size);
  71     }
  72
  73   for (i = 0; i < n_gfds; ++i)
  74     {
  75       if (gfds[i].events & G_IO_IN)
  76         {
  77           FD_SET (gfds[i].fd, &all_rfds);
  78           if (gfds[i].fd > max_fds) max_fds = gfds[i].fd;
  79         }
  80       if (gfds[i].events & G_IO_OUT)
  81         {
  82           FD_SET (gfds[i].fd, &all_wfds);
  83           if (gfds[i].fd > max_fds) max_fds = gfds[i].fd;
  84           have_wfds = 1;
  85         }
  86     }
  87
  88   SAFE_FREE ();
  89
  90   if (tmo_in_millisec >= 0)
  91     {
  92       tmo = make_timespec (tmo_in_millisec / 1000,
  93                            1000 * 1000 * (tmo_in_millisec % 1000));
  94       if (!timeout || timespec_cmp (tmo, *timeout) < 0)
  95         tmop = &tmo;
  96     }
  97
  98   fds_lim = max_fds + 1;
  99   nfds = pselect (fds_lim, &all_rfds, have_wfds ? &all_wfds : NULL,
 100                   efds, tmop, sigmask);
 101
 102   if (nfds < 0)
 103     retval = nfds;
 104   else if (nfds > 0)
 105     {
 106       for (i = 0; i < fds_lim; ++i)
 107         {
 108           if (FD_ISSET (i, &all_rfds))
 109             {
 110               if (rfds && FD_ISSET (i, rfds)) ++retval;
 111               else ++our_fds;
 112             }
 113           else if (rfds)
 114             FD_CLR (i, rfds);
 115
 116           if (have_wfds && FD_ISSET (i, &all_wfds))
 117             {
 118               if (wfds && FD_ISSET (i, wfds)) ++retval;
 119               else ++our_fds;
 120             }
 121           else if (wfds)
 122             FD_CLR (i, wfds);
 123
 124           if (efds && FD_ISSET (i, efds))
 125             ++retval;
 126         }
 127     }
 128
 129   /* If Gtk+ is in use eventually gtk_main_iteration will be called,
 130      unless retval is zero.  */
 131 #ifdef USE_GTK
 132   need_to_dispatch = retval == 0;
 133 #else
 134   need_to_dispatch = true;
 135 #endif
 136   if (need_to_dispatch)
 137     {
 138       int pselect_errno = errno;
 139       while (g_main_context_pending (context))
 140         g_main_context_dispatch (context);
 141       errno = pselect_errno;
 142     }
 143
 144   /* To not have to recalculate timeout, return like this.  */
 145   if ((our_fds > 0 || (nfds == 0 && tmop == &tmo)) && (retval == 0))
 146     {
 147       retval = -1;
 148       errno = EINTR;
 149     }
 150
 151   return retval;
 152 }
 153 #endif /* HAVE_GLIB */