/src/xgselect.c
C | 164 lines | 110 code | 20 blank | 34 comment | 43 complexity | 6726f8c6ff206ae5e3adc166e1437396 MD5 | raw file
- /* Function for handling the GLib event loop.
- Copyright (C) 2009-2014 Free Software Foundation, Inc.
- This file is part of GNU Emacs.
- GNU Emacs is free software: you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation, either version 3 of the License, or
- (at your option) any later version.
- GNU Emacs is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
- #include <config.h>
- #include "xgselect.h"
- #ifdef HAVE_GLIB
- #include <glib.h>
- #include <errno.h>
- #include <stdbool.h>
- #include <timespec.h>
- #include "frame.h"
- #include "blockinput.h"
- /* `xg_select' is a `pselect' replacement. Why do we need a separate function?
- 1. Timeouts. Glib and Gtk rely on timer events. If we did pselect
- with a greater timeout then the one scheduled by Glib, we would
- not allow Glib to process its timer events. We want Glib to
- work smoothly, so we need to reduce our timeout to match Glib.
- 2. Descriptors. Glib may listen to more file descriptors than we do.
- So we add Glib descriptors to our pselect pool, but we don't change
- the value returned by the function. The return value matches only
- the descriptors passed as arguments, making it compatible with
- plain pselect. */
- int
- xg_select (int fds_lim, fd_set *rfds, fd_set *wfds, fd_set *efds,
- struct timespec const *timeout, sigset_t const *sigmask)
- {
- fd_set all_rfds, all_wfds;
- struct timespec tmo;
- struct timespec const *tmop = timeout;
- GMainContext *context;
- int have_wfds = wfds != NULL;
- GPollFD gfds_buf[128];
- GPollFD *gfds = gfds_buf;
- int gfds_size = sizeof gfds_buf / sizeof *gfds_buf;
- int n_gfds, retval = 0, our_fds = 0, max_fds = fds_lim - 1;
- int i, nfds, tmo_in_millisec;
- bool need_to_dispatch;
- USE_SAFE_ALLOCA;
- context = g_main_context_default ();
- if (rfds) all_rfds = *rfds;
- else FD_ZERO (&all_rfds);
- if (wfds) all_wfds = *wfds;
- else FD_ZERO (&all_wfds);
- n_gfds = g_main_context_query (context, G_PRIORITY_LOW, &tmo_in_millisec,
- gfds, gfds_size);
- if (gfds_size < n_gfds)
- {
- SAFE_NALLOCA (gfds, sizeof *gfds, n_gfds);
- gfds_size = n_gfds;
- n_gfds = g_main_context_query (context, G_PRIORITY_LOW, &tmo_in_millisec,
- gfds, gfds_size);
- }
- for (i = 0; i < n_gfds; ++i)
- {
- if (gfds[i].events & G_IO_IN)
- {
- FD_SET (gfds[i].fd, &all_rfds);
- if (gfds[i].fd > max_fds) max_fds = gfds[i].fd;
- }
- if (gfds[i].events & G_IO_OUT)
- {
- FD_SET (gfds[i].fd, &all_wfds);
- if (gfds[i].fd > max_fds) max_fds = gfds[i].fd;
- have_wfds = 1;
- }
- }
- SAFE_FREE ();
- if (tmo_in_millisec >= 0)
- {
- tmo = make_timespec (tmo_in_millisec / 1000,
- 1000 * 1000 * (tmo_in_millisec % 1000));
- if (!timeout || timespec_cmp (tmo, *timeout) < 0)
- tmop = &tmo;
- }
- fds_lim = max_fds + 1;
- nfds = pselect (fds_lim, &all_rfds, have_wfds ? &all_wfds : NULL,
- efds, tmop, sigmask);
- if (nfds < 0)
- retval = nfds;
- else if (nfds > 0)
- {
- for (i = 0; i < fds_lim; ++i)
- {
- if (FD_ISSET (i, &all_rfds))
- {
- if (rfds && FD_ISSET (i, rfds)) ++retval;
- else ++our_fds;
- }
- else if (rfds)
- FD_CLR (i, rfds);
- if (have_wfds && FD_ISSET (i, &all_wfds))
- {
- if (wfds && FD_ISSET (i, wfds)) ++retval;
- else ++our_fds;
- }
- else if (wfds)
- FD_CLR (i, wfds);
- if (efds && FD_ISSET (i, efds))
- ++retval;
- }
- }
- /* If Gtk+ is in use eventually gtk_main_iteration will be called,
- unless retval is zero. */
- #ifdef USE_GTK
- need_to_dispatch = retval == 0;
- #else
- need_to_dispatch = true;
- #endif
- if (need_to_dispatch)
- {
- int pselect_errno = errno;
- /* Prevent g_main_dispatch recursion, that would occur without
- block_input wrapper, because event handlers call
- unblock_input. Event loop recursion was causing Bug#15801. */
- block_input ();
- while (g_main_context_pending (context))
- g_main_context_dispatch (context);
- unblock_input ();
- errno = pselect_errno;
- }
- /* To not have to recalculate timeout, return like this. */
- if ((our_fds > 0 || (nfds == 0 && tmop == &tmo)) && (retval == 0))
- {
- retval = -1;
- errno = EINTR;
- }
- return retval;
- }
- #endif /* HAVE_GLIB */