src/xgselect.c

   1 /* Function for handling the GLib event loop.
   2
   3 Copyright (C) 2009-2011  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 #if defined (USE_GTK) || defined (HAVE_GCONF)
  23 #include <glib.h>
  24 #include <errno.h>
  25 #include <setjmp.h>
  26 #include "xgselect.h"
  27
  28 static GPollFD *gfds;
  29 static int gfds_size;
  30
  31 int
  32 xg_select (int max_fds, SELECT_TYPE *rfds, SELECT_TYPE *wfds, SELECT_TYPE *efds,
  33            EMACS_TIME *timeout)
  34 {
  35   SELECT_TYPE all_rfds, all_wfds;
  36   EMACS_TIME tmo, *tmop = timeout;
  37
  38   GMainContext *context = g_main_context_default ();
  39   int have_wfds = wfds != NULL;
  40   int n_gfds = 0, our_tmo = 0, retval = 0, our_fds = 0;
  41   int i, nfds, tmo_in_millisec;
  42
  43   if (rfds) memcpy (&all_rfds, rfds, sizeof (all_rfds));
  44   else FD_ZERO (&all_rfds);
  45   if (wfds) memcpy (&all_wfds, wfds, sizeof (all_rfds));
  46   else FD_ZERO (&all_wfds);
  47
  48   /* Update event sources in GLib. */
  49   g_main_context_pending (context);
  50
  51   do {
  52     if (n_gfds > gfds_size)
  53       {
  54         while (n_gfds > gfds_size)
  55           gfds_size *= 2;
  56         xfree (gfds);
  57         gfds = xmalloc (sizeof (*gfds) * gfds_size);
  58       }
  59
  60     n_gfds = g_main_context_query (context,
  61                                    G_PRIORITY_LOW,
  62                                    &tmo_in_millisec,
  63                                    gfds,
  64                                    gfds_size);
  65   } while (n_gfds > gfds_size);
  66
  67   for (i = 0; i < n_gfds; ++i)
  68     {
  69       if (gfds[i].events & G_IO_IN)
  70         {
  71           FD_SET (gfds[i].fd, &all_rfds);
  72           if (gfds[i].fd > max_fds) max_fds = gfds[i].fd;
  73         }
  74       if (gfds[i].events & G_IO_OUT)
  75         {
  76           FD_SET (gfds[i].fd, &all_wfds);
  77           if (gfds[i].fd > max_fds) max_fds = gfds[i].fd;
  78           have_wfds = 1;
  79         }
  80     }
  81
  82   if (tmo_in_millisec >= 0)
  83     {
  84       EMACS_SET_SECS_USECS (tmo, tmo_in_millisec/1000,
  85                             1000 * (tmo_in_millisec % 1000));
  86       if (!timeout) our_tmo = 1;
  87       else
  88         {
  89           EMACS_TIME difference;
  90
  91           EMACS_SUB_TIME (difference, tmo, *timeout);
  92           if (EMACS_TIME_NEG_P (difference)) our_tmo = 1;
  93         }
  94
  95       if (our_tmo) tmop = &tmo;
  96     }
  97
  98   nfds = select (max_fds+1, &all_rfds, have_wfds ? &all_wfds : NULL,
  99                  efds, tmop);
 100
 101   if (nfds < 0)
 102     retval = nfds;
 103   else if (nfds > 0)
 104     {
 105       for (i = 0; i < max_fds+1; ++i)
 106         {
 107           if (FD_ISSET (i, &all_rfds))
 108             {
 109               if (rfds && FD_ISSET (i, rfds)) ++retval;
 110               else ++our_fds;
 111             }
 112           else if (rfds)
 113             FD_CLR (i, rfds);
 114
 115           if (have_wfds && FD_ISSET (i, &all_wfds))
 116             {
 117               if (wfds && FD_ISSET (i, wfds)) ++retval;
 118               else ++our_fds;
 119             }
 120           else if (wfds)
 121             FD_CLR (i, wfds);
 122
 123           if (efds && FD_ISSET (i, efds))
 124             ++retval;
 125         }
 126     }
 127
 128   if (our_fds > 0 || (nfds == 0 && our_tmo))
 129     {
 130
 131       /* If Gtk+ is in use eventually gtk_main_iteration will be called,
 132          unless retval is zero.  */
 133 #ifdef USE_GTK
 134       if (retval == 0)
 135 #endif
 136         while (g_main_context_pending (context))
 137           g_main_context_dispatch (context);
 138
 139       /* To not have to recalculate timeout, return like this.  */
 140       if (retval == 0)
 141         {
 142           retval = -1;
 143           errno = EINTR;
 144         }
 145     }
 146
 147   return retval;
 148 }
 149 #endif /* defined (USE_GTK) || defined (HAVE_GCONF) */
 150
 151 void
 152 xgselect_initialize (void)
 153 {
 154 #if defined (USE_GTK) || defined (HAVE_GCONF)
 155   gfds_size = 128;
 156   gfds = xmalloc (sizeof (*gfds)*gfds_size);
 157 #endif /* defined (USE_GTK) || defined (HAVE_GCONF) */
 158 }