Package: ctwm
Version: 3.7-3.2
Severity: important
Tags: upstream patch
Dear Maintainer,
I'm a longtime CTWM user who finally got tired of the random
crashes that occur, typically when I'm switching workspaces.
I can sometimes go for a month without seeing them and sometimes
it happens several times a day. I've analyzed this to the point
where I can see that code in DispatchEvent() is occasionally
leaving the global Scr pointer NULL which causes a SIGSEGV on
our next pass through the loop in HandleEvents().
I've provided a patch that adds a few lines of defensive code
which seems to have improved the situation, though I have not
analyzed the root cause, which appears to be that, for unknown
reasons, either XFindContext() or FindScreenInfo() seem to be
unable to return the answer expected of them.
--Michael O'Donnell
BEGIN PATCH:
--- events.c.b0rken 2012-03-06 15:10:42.093677349 -0500
+++ events.c 2012-03-06 15:19:52.369161662 -0500
@@ -435,21 +435,25 @@
*/
Bool DispatchEvent2 (void)
{
Window w = Event.xany.window;
StashEventTime (&Event);
+ ScreenInfo *lastScr = Scr; /* XXX_MIKE - assume Scr OK on entry... */
if (XFindContext (dpy, w, TwmContext, (XPointer *) &Tmp_win) == XCNOENT)
Tmp_win = NULL;
if (XFindContext (dpy, w, ScreenContext, (XPointer *)&Scr) == XCNOENT) {
Scr = FindScreenInfo (WindowOfEvent (&Event));
}
dumpevent(&Event);
- if (!Scr) return False;
+ if (!Scr) {
+ Scr = lastScr; /* XXX_MIKE - try not to leave Scr NULL */
+ return False;
+ }
if (Scr->Root != Scr->RealRoot) FixRootEvent (&Event);
#ifdef SOUNDS
play_sound(Event.type);
#endif
@@ -473,21 +477,25 @@
*/
Bool DispatchEvent (void)
{
Window w = Event.xany.window;
StashEventTime (&Event);
+ ScreenInfo *lastScr = Scr; /* XXX_MIKE - assume Scr OK on entry... */
if (XFindContext (dpy, w, TwmContext, (XPointer *) &Tmp_win) == XCNOENT)
Tmp_win = NULL;
if (XFindContext (dpy, w, ScreenContext, (XPointer *)&Scr) == XCNOENT) {
Scr = FindScreenInfo (WindowOfEvent (&Event));
}
dumpevent(&Event);
- if (!Scr) return False;
+ if (!Scr) {
+ Scr = lastScr; /* XXX_MIKE - try not to leave Scr NULL */
+ return False;
+ }
if (captive) {
if ((Event.type == ConfigureNotify) && (Event.xconfigure.window ==
Scr->CaptiveRoot)) {
ConfigureRootWindow (&Event);
return (False);
END PATCH
-- System Information:
Debian Release: wheezy/sid
APT prefers testing
APT policy: (990, 'testing'), (500, 'unstable')
Architecture: i386 (i686)
Kernel: Linux 3.1.0 (SMP w/2 CPU cores)
Locale: LANG=en_US, LC_CTYPE=en_US (charmap=ISO-8859-1)
Shell: /bin/sh linked to /bin/bash
Versions of packages ctwm depends on:
ii libc6 2.13-26
ii libice6 2:1.0.7-2
ii libjpeg8 8d-1
ii librplay3 3.3.2-14
ii libsm6 2:1.2.0-2
ii libx11-6 2:1.4.4-4
ii libxext6 2:1.3.0-3
ii libxmu6 2:1.1.0-3
ii libxpm4 1:3.5.9-4
ii libxt6 1:1.1.1-2
ii m4 1.4.16-2
ii x11-common 1:7.6+11
ctwm recommends no packages.
ctwm suggests no packages.
-- Configuration Files:
/etc/X11/ctwm/system.ctwmrc [Errno 2] No such file or directory:
u'/etc/X11/ctwm/system.ctwmrc'
-- no debconf information
-- debsums errors found:
debsums: missing file /usr/bin/ctwm (from ctwm package)
Note that the above mentioned debsums errors are due to my
having built and installed a private version during debug....
--
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