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