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