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/*
X11 support for the Midnight Commander.
Copyright (C) 2005-2022
Free Software Foundation, Inc.
Written by:
Roland Illig <roland.illig@gmx.de>, 2005.
This file is part of the Midnight Commander.
The Midnight Commander 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.
The Midnight Commander 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, see <http://www.gnu.org/licenses/>.
*/
/** \file x11conn.c
* \brief Source: X11 support
* \warning This code uses setjmp() and longjmp(). Before you modify _anything_ here,
* please read the relevant sections of the C standard.
*/
#include <config.h>
#include <setjmp.h>
#include <X11/Xlib.h>
#ifdef HAVE_GMODULE
#include <gmodule.h>
#endif
#include "lib/global.h"
#include "x11conn.h"
/*** global variables ****************************************************************************/
/*** file scope macro definitions ****************************************************************/
#ifndef HAVE_GMODULE
#define func_XOpenDisplay XOpenDisplay
#define func_XCloseDisplay XCloseDisplay
#define func_XSetErrorHandler XSetErrorHandler
#define func_XSetIOErrorHandler XSetIOErrorHandler
#define func_XQueryPointer XQueryPointer
#endif
/*** file scope type declarations ****************************************************************/
typedef int (*mc_XErrorHandler_callback) (Display *, XErrorEvent *);
typedef int (*mc_XIOErrorHandler_callback) (Display *);
/*** file scope variables ************************************************************************/
#ifdef HAVE_GMODULE
static Display *(*func_XOpenDisplay) (_Xconst char *);
static int (*func_XCloseDisplay) (Display *);
static mc_XErrorHandler_callback (*func_XSetErrorHandler) (mc_XErrorHandler_callback);
static mc_XIOErrorHandler_callback (*func_XSetIOErrorHandler) (mc_XIOErrorHandler_callback);
static Bool (*func_XQueryPointer) (Display *, Window, Window *, Window *,
int *, int *, int *, int *, unsigned int *);
static GModule *x11_module;
#endif
static gboolean handlers_installed = FALSE;
/* This flag is set as soon as an X11 error is reported. Usually that
* means that the DISPLAY is not available anymore. We do not try to
* reconnect, as that would violate the X11 protocol. */
static gboolean lost_connection = FALSE;
static jmp_buf x11_exception; /* FIXME: get a better name */
static gboolean longjmp_allowed = FALSE;
/*** file scope functions ************************************************************************/
/* --------------------------------------------------------------------------------------------- */
static int
x_io_error_handler (Display * dpy)
{
(void) dpy;
lost_connection = TRUE;
if (longjmp_allowed)
{
longjmp_allowed = FALSE;
longjmp (x11_exception, 1);
}
return 0;
}
/* --------------------------------------------------------------------------------------------- */
static int
x_error_handler (Display * dpy, XErrorEvent * ee)
{
(void) ee;
(void) func_XCloseDisplay (dpy);
return x_io_error_handler (dpy);
}
/* --------------------------------------------------------------------------------------------- */
static void
install_error_handlers (void)
{
if (handlers_installed)
return;
(void) func_XSetErrorHandler (x_error_handler);
(void) func_XSetIOErrorHandler (x_io_error_handler);
handlers_installed = TRUE;
}
/* --------------------------------------------------------------------------------------------- */
static gboolean
x11_available (void)
{
#ifdef HAVE_GMODULE
gchar *x11_module_fname;
if (lost_connection)
return FALSE;
if (x11_module != NULL)
return TRUE;
x11_module_fname = g_module_build_path (NULL, "X11");
x11_module = g_module_open (x11_module_fname, G_MODULE_BIND_LAZY);
if (x11_module == NULL)
x11_module = g_module_open ("libX11.so.6", G_MODULE_BIND_LAZY);
g_free (x11_module_fname);
if (x11_module == NULL)
return FALSE;
if (!g_module_symbol (x11_module, "XOpenDisplay", (void *) &func_XOpenDisplay))
goto cleanup;
if (!g_module_symbol (x11_module, "XCloseDisplay", (void *) &func_XCloseDisplay))
goto cleanup;
if (!g_module_symbol (x11_module, "XQueryPointer", (void *) &func_XQueryPointer))
goto cleanup;
if (!g_module_symbol (x11_module, "XSetErrorHandler", (void *) &func_XSetErrorHandler))
goto cleanup;
if (!g_module_symbol (x11_module, "XSetIOErrorHandler", (void *) &func_XSetIOErrorHandler))
goto cleanup;
install_error_handlers ();
return TRUE;
cleanup:
func_XOpenDisplay = 0;
func_XCloseDisplay = 0;
func_XQueryPointer = 0;
func_XSetErrorHandler = 0;
func_XSetIOErrorHandler = 0;
g_module_close (x11_module);
x11_module = NULL;
return FALSE;
#else
install_error_handlers ();
return !(lost_connection);
#endif
}
/* --------------------------------------------------------------------------------------------- */
/*** public functions ****************************************************************************/
/* --------------------------------------------------------------------------------------------- */
Display *
mc_XOpenDisplay (const char *displayname)
{
if (x11_available ())
{
if (setjmp (x11_exception) == 0)
{
Display *retval;
/* cppcheck-suppress redundantAssignment */
longjmp_allowed = TRUE;
retval = func_XOpenDisplay (displayname);
/* cppcheck-suppress redundantAssignment */
longjmp_allowed = FALSE;
return retval;
}
}
return NULL;
}
/* --------------------------------------------------------------------------------------------- */
int
mc_XCloseDisplay (Display * display)
{
if (x11_available ())
{
if (setjmp (x11_exception) == 0)
{
int retval;
/* cppcheck-suppress redundantAssignment */
longjmp_allowed = TRUE;
retval = func_XCloseDisplay (display);
/* cppcheck-suppress redundantAssignment */
longjmp_allowed = FALSE;
return retval;
}
}
return 0;
}
/* --------------------------------------------------------------------------------------------- */
Bool
mc_XQueryPointer (Display * display, Window win, Window * root_return,
Window * child_return, int *root_x_return, int *root_y_return,
int *win_x_return, int *win_y_return, unsigned int *mask_return)
{
Bool retval;
if (x11_available ())
{
if (setjmp (x11_exception) == 0)
{
/* cppcheck-suppress redundantAssignment */
longjmp_allowed = TRUE;
retval = func_XQueryPointer (display, win, root_return,
child_return, root_x_return, root_y_return,
win_x_return, win_y_return, mask_return);
/* cppcheck-suppress redundantAssignment */
longjmp_allowed = FALSE;
return retval;
}
}
*root_return = None;
*child_return = None;
*root_x_return = 0;
*root_y_return = 0;
*win_x_return = 0;
*win_y_return = 0;
*mask_return = 0;
return False;
}
/* --------------------------------------------------------------------------------------------- */
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