* x11conn.c: Separated X11 connection handling from key.c. Added

error handling for X11 errors and connection errors.
	* x11conn.h: The interface for x11conn.h.
	* key.c: Now using the x11conn code.
	* Makefile.am: Added x11conn.{h,c}.

src/ChangeLog

@@ -1,3 +1,11 @@
+2005-03-10  Roland Illig  <roland.illig@gmx.de>
+
+	* x11conn.c: Separated X11 connection handling from key.c. Added
+	error handling for X11 errors and connection errors.
+	* x11conn.h: The interface for x11conn.h.
+	* key.c: Now using the x11conn code.
+	* Makefile.am: Added x11conn.{h,c}.
+
 2005-02-26  Miguel de Icaza  <miguel@novell.com>
 
 	* screen.c (chdir_other_panel): Restored original functionality.

src/Makefile.am

@@ -59,7 +59,8 @@ SRCS =	achown.c achown.h background.c background.h boxes.c boxes.h	\
 	slint.c	subshell.c subshell.h textconf.c textconf.h		\
 	tree.c tree.h treestore.c treestore.h tty.h user.c user.h	\
 	util.c util.h utilunix.c view.c view.h vfsdummy.h widget.c	\
-	widget.h win.c win.h wtools.c wtools.h unixcompat.h
+	widget.h win.c win.h wtools.c wtools.h unixcompat.h		\
+	x11conn.h x11conn.c
 
 if CHARSET
 mc_SOURCES = $(SRCS) $(CHARSET_SRC)

src/key.c

@@ -45,10 +45,7 @@
 #endif
 
 #ifdef HAVE_TEXTMODE_X11_SUPPORT
-#ifdef HAVE_GMODULE
+#    include "x11conn.h"
-#include <gmodule.h>
-#endif /* HAVE_GMODULE */
-#include <X11/Xlib.h>
 #endif
 
 #ifdef __linux__
@@ -406,52 +403,16 @@ define_sequences (key_define_t *kd)
 
 #ifdef HAVE_TEXTMODE_X11_SUPPORT
 
-#ifdef HAVE_GMODULE
-static int (*func_XCloseDisplay) (Display *);
-static Bool (*func_XQueryPointer) (Display *, Window, Window *, Window *,
-				   int *, int *, int *, int *,
-				   unsigned int *);
-
-static GModule *x11_module;
-#endif				/* HAVE_GMODULE */
-
 static Display *x11_display;
 static Window x11_window;
 
 static void
 init_key_x11 (void)
 {
-#ifdef HAVE_GMODULE
-    static Display *(*func_XOpenDisplay) (_Xconst char *);
-    gchar *x11_module_fname;
-#endif				/* HAVE_GMODULE */
-
     if (!getenv ("DISPLAY"))
 	return;
 
-#ifdef HAVE_GMODULE
+    x11_display = mc_XOpenDisplay (0);
-    x11_module_fname = g_module_build_path (NULL, "X11");
-
-    if (!x11_module_fname)
-	return;
-
-    x11_module = g_module_open (x11_module_fname, G_MODULE_BIND_LAZY);
-    g_free (x11_module_fname);
-
-    if (!x11_module)
-	return;
-
-    if (g_module_symbol
-	(x11_module, "XOpenDisplay", (void *) &func_XOpenDisplay)
-	&& g_module_symbol (x11_module, "XCloseDisplay",
-			    (void *) &func_XCloseDisplay)
-	&& g_module_symbol (x11_module, "XQueryPointer",
-			    (void *) &func_XQueryPointer)) {
-	x11_display = (*func_XOpenDisplay) (0);
-    }
-#else
-    x11_display = XOpenDisplay (0);
-#endif				/* HAVE_GMODULE */
 
     if (x11_display)
 	x11_window = DefaultRootWindow (x11_display);
@@ -1324,13 +1285,8 @@ get_modifier (void)
 	int win_x, win_y;
 	unsigned int mask;
 
-#ifdef HAVE_GMODULE
+	mc_XQueryPointer (x11_display, x11_window, &root, &child, &root_x,
-	(*func_XQueryPointer) (x11_display, x11_window, &root, &child,
-			       &root_x, &root_y, &win_x, &win_y, &mask);
-#else
-	XQueryPointer (x11_display, x11_window, &root, &child, &root_x,
 		       &root_y, &win_x, &win_y, &mask);
-#endif				/* HAVE_GMODULE */
 
 	if (mask & ShiftMask)
 	    result |= KEY_M_SHIFT;
@@ -1440,14 +1396,7 @@ void done_key ()
     s_dispose (select_list);
 
 #ifdef HAVE_TEXTMODE_X11_SUPPORT
-#ifdef HAVE_GMODULE
     if (x11_display)
-	(*func_XCloseDisplay) (x11_display);
+	mc_XCloseDisplay (x11_display);
-    if (x11_module)
+#endif
-	g_module_close (x11_module);
-#else
-    if (x11_display)
-	XCloseDisplay (x11_display);
-#endif /* HAVE_GMODULE */
-#endif /* HAVE_TEXTMODE_X11_SUPPORT */
 }

src/x11conn.c

@@ -0,0 +1,232 @@
+/*
+   X11 support for the Midnight Commander.
+
+   Copyright (C) 2005 The Free Software Foundation
+
+   Written by:
+   Roland Illig <roland.illig@gmx.de>, 2005.
+
+   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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/*
+   !!! WARNING !!!
+
+   This code uses setjmp() and longjmp(). Before you modify _anything_
+   here, please read the relevant sections of the C standard.
+*/
+
+#include <config.h>
+
+#ifndef HAVE_TEXTMODE_X11_SUPPORT
+typedef int dummy;		/* C99 forbids empty compilation unit */
+#else
+
+#include <setjmp.h>
+
+#include <X11/Xlib.h>
+
+#include "../src/global.h"
+
+#ifdef HAVE_GMODULE
+#  include <gmodule.h>
+#endif
+
+#include "x11conn.h"
+
+/*** 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;
+
+#else
+
+#define func_XOpenDisplay	XOpenDisplay
+#define func_XCloseDisplay	XCloseDisplay
+#define func_XSetErrorHandler	XSetErrorHandler
+#define func_XSetIOErrorHandler	XSetIOErrorHandler
+#define func_XQueryPointer	XQueryPointer
+
+#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 private 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;
+    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");
+
+    if (x11_module_fname == NULL)
+	return FALSE;
+
+    x11_module = g_module_open (x11_module_fname, 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)
+{
+    Display *retval;
+
+    if (x11_available()) {
+	if (setjmp(x11_exception) == 0) {
+	    longjmp_allowed = TRUE;
+	    retval = func_XOpenDisplay (displayname);
+	    longjmp_allowed = FALSE;
+	    return retval;
+	}
+    }
+    return NULL;
+}
+
+int mc_XCloseDisplay (Display *display)
+{
+    int retval;
+
+    if (x11_available()) {
+	if (setjmp(x11_exception) == 0) {
+	    longjmp_allowed = TRUE;
+	    retval = func_XCloseDisplay (display);
+	    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) {
+	    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);
+	    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;
+}
+
+#endif /* HAVE_TEXTMODE_X11_SUPPORT */

src/x11conn.h

@@ -0,0 +1,21 @@
+#ifndef MC_X11CONN_H
+#define MC_X11CONN_H
+
+/*
+   This module provides support for some X11 functions.  The functions
+   are loaded dynamically if GModule is available, and statically if
+   not.  X11 session handling is somewhat robust.  If there is an X11
+   error or a connection error, all further traffic to the X server
+   will be suppressed, and the functions will return reasonable default
+   values.
+*/
+
+#include <X11/Xlib.h>
+
+extern Display *mc_XOpenDisplay (const char *);
+extern int mc_XCloseDisplay (Display *);
+
+extern Bool mc_XQueryPointer (Display *, Window, Window *, Window *,
+	int *, int *, int *, int *, unsigned int *);
+
+#endif