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/* Copyright (C) 2006-2020 J.F.Dockes
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the
* Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
// Poll state of X11 connectibility (to detect end of user session).
#include "autoconfig.h"
#ifndef DISABLE_X11MON
#include "x11mon.h"
#include <stdio.h>
#include <X11/Xlib.h>
#include <signal.h>
#include <setjmp.h>
#include "log.h"
static Display *m_display;
static bool m_ok;
static jmp_buf env;
static int errorHandler(Display *, XErrorEvent*)
{
LOGERR("x11mon: error handler: Got X11 error\n");
m_ok = false;
return 0;
}
static int ioErrorHandler(Display *)
{
LOGERR("x11mon: error handler: Got X11 IO error\n");
m_ok = false;
m_display = nullptr;
longjmp(env, 1);
}
bool x11IsAlive()
{
// Xlib always exits on IO errors. Need a setjmp to avoid this (will jump
// from IO error handler instead of returning).
if (setjmp(env)) {
LOGDEB("x11IsAlive: got long jump: X11 error\n");
return false;
}
if (nullptr == m_display) {
signal(SIGPIPE, SIG_IGN);
XSetErrorHandler(errorHandler);
XSetIOErrorHandler(ioErrorHandler);
if ((m_display = XOpenDisplay(nullptr)) == nullptr) {
LOGERR("x11IsAlive: cant connect\n");
m_ok = false;
return false;
}
}
m_ok = true;
bool sync= XSynchronize(m_display, true);
XNoOp(m_display);
XSynchronize(m_display, sync);
return m_ok;
}
#else // DISABLE_X11MON->
bool x11IsAlive()
{
return true;
}
#endif /* DISABLE_X11MON */
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