Created attachment 2988 [details]
File that makes kwrite crash on CTRL-w

I uploaded as application/octet-stream, because there are special characters in
the file (IIRC the german umlauts inside this file are UTF-8 coded.

I can't reproduce the crash (HEAD 20031026).

I can reproduce it anytime. Here's the gdb info (crash point, backtrace). The main reasons seems to be, that the variable "a" is a null pointer. I traced it and saw that at line 302 of katerenderer.cpp, a 0-pointer is returned, as soon as I press CTRL-W:
302       a = textLine->attributes ();

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 16384 (LWP 9789)]
0x41fb1e4d in KateRenderer::paintTextLine(QPainter&, LineRange const*, int, int, KateTextCursor const*, KateTextRange const*) (
    this=0x8105158, paint=@0xbfffe880, range=0x825cd20, xStart=0, xEnd=680, cursor=0x81a862c, bracketmark=0x81a865c)
    at katerenderer.cpp:376
376           KateAttribute* curAt = ((*a) >= atLen) ? &at[0] : &at[*a];
(gdb) bt
#0  0x41fb1e4d in KateRenderer::paintTextLine(QPainter&, LineRange const*, int, int, KateTextCursor const*, KateTextRange const*) (this=0x8105158, paint=@0xbfffe880, range=0x825cd20, xStart=0, xEnd=680, cursor=0x81a862c, bracketmark=0x81a865c)
    at katerenderer.cpp:376
#1  0x41f92e88 in KateViewInternal::paintText(int, int, int, int, bool) (this=0x81a8560, x=0, y=0, width=680, height=400,
    paintOnlyDirty=true) at kateviewinternal.cpp:751
#2  0x41f9896c in KateViewInternal::paintCursor() (this=0x81a8560) at kateviewinternal.cpp:2051
#3  0x41f9a81b in KateViewInternal::cursorTimeout() (this=0x81a8560) at kateviewinternal.cpp:2547
#4  0x41f8eba7 in KateViewInternal::qt_invoke(int, QUObject*) (this=0x81a8560, _id=63, _o=0xbfffec10)
    at kateviewinternal.moc:279
#5  0x40ca3dd9 in QObject::activate_signal(QConnectionList*, QUObject*) (this=0x81a8768, clist=0x81a04d0, o=0xbfffec10)
    at kernel/qobject.cpp:2333
#6  0x40ca3c78 in QObject::activate_signal(int) (this=0x81a8768, signal=2) at kernel/qobject.cpp:2302
#7  0x40fe81ae in QTimer::timeout() (this=0x81a8768) at .moc/debug-shared-mt/moc_qtimer.cpp:82
#8  0x40cc8407 in QTimer::event(QEvent*) (this=0x81a8768, e=0xbfffee60) at kernel/qtimer.cpp:219
#9  0x40c410af in QApplication::internalNotify(QObject*, QEvent*) (this=0xbffff120, receiver=0x81a8768, e=0xbfffee60)
    at kernel/qapplication.cpp:2582
#10 0x40c4056c in QApplication::notify(QObject*, QEvent*) (this=0xbffff120, receiver=0x81a8768, e=0xbfffee60)
    at kernel/qapplication.cpp:2305
#11 0x407ac434 in KApplication::notify(QObject*, QEvent*) (this=0xbffff120, receiver=0x81a8768, event=0xbfffee60)
    at kapplication.cpp:509
#12 0x4002cf9d in QApplication::sendEvent(QObject*, QEvent*) (receiver=0x81a8768, event=0xbfffee60) at qapplication.h:490
#13 0x40c2f17c in QEventLoop::activateTimers() (this=0x80c2fa8) at kernel/qeventloop_unix.cpp:557
#14 0x40be9b0a in QEventLoop::processEvents(unsigned) (this=0x80c2fa8, flags=4) at kernel/qeventloop_x11.cpp:346
#15 0x40c56b02 in QEventLoop::enterLoop() (this=0x80c2fa8) at kernel/qeventloop.cpp:198
#16 0x40c56a1e in QEventLoop::exec() (this=0x80c2fa8) at kernel/qeventloop.cpp:145
#17 0x40c4122f in QApplication::exec() (this=0xbffff120) at kernel/qapplication.cpp:2705
#18 0x4002b8f3 in kdemain (argc=1, argv=0xbffff2b4) at kwritemain.cpp:676
#19 0x080486ba in main (argc=1, argv=0xbffff2b4) at kwrite.la.cpp:2


Hope this helps.  Best regards,
      Chris

PS: No, I have not (yet) found another file where the bug is triggered. I am pretty sure that it is some kind of "timing problem" (a half-destroyed object or so). I will try to debug this some more.

My personal workaround is in katerenderer.cpp:

  // text + attrib data from line
  a = textLine->attributes ();
+  if ( a == 0 ) {
+        return;
+  }

BTW: It only happens with kwrite, not with kate. The bug has been there at least since 2003-09-26. I did not want to report it then, to exclude the possibility of a broken installation. I have compiled/installed KDE CVS today *completely*, so I decided to report this now.

Confirmed, will fix soon...

*** Bug 63857 has been marked as a duplicate of this bug. ***

Hmm.  For the record, the final cause of this crashing is the first time the cursor blinks after the file is closed.  However, the reason for us getting into a crashable state remains a mystery to me.

I am now unable to reproduce the crash :(  I didn't change much, just recompiled qt, but neither a debug nor a non-debug build trigger the crash any more.

So, I'm committing a workaround which I know will stop the crash, but not get to the root of the problem, whatever it is.  I can't think of anything else to do at the moment.

Christoph - any ideas why the sidebar doesn't get properly repainted after closing this file in kwrite?  For other longer files it is repainted fine...

Subject: kdelibs/kate/part

CVS commit by rodda: 

Workaround-fix for mystery renderer crash bug.

CCMAIL: 67065-done@bugs.kde.org


  M +3 -2      katerenderer.cpp   1.34


--- kdelibs/kate/part/katerenderer.cpp  #1.33:1.34
@@ -301,4 +301,5 @@ void KateRenderer::paintTextLine(QPainte
   // text + attrib data from line
   a = textLine->attributes ();
+  bool noAttribs = !a;
 
   // adjust to startcol ;)
@@ -374,5 +375,5 @@ void KateRenderer::paintTextLine(QPainte
       // Determine current syntax highlighting attribute
       // A bit legacy but doesn't need to change
-      KateAttribute* curAt = ((*a) >= atLen) ? &at[0] : &at[*a];
+      KateAttribute* curAt = (!noAttribs && (*a) >= atLen) ? &at[0] : &at[*a];
 
       // X position calculation. Incorrect for fonts with non-zero leftBearing() and rightBearing() results.
@@ -466,5 +467,5 @@ void KateRenderer::paintTextLine(QPainte
 
             // it is a different attribute OR
-            (curAt != &at[*(a+1)]) ||
+            (!noAttribs && curAt != &at[*(a+1)]) ||
 
             // the selection boundary was crossed OR

kwrite craches when closing :
Using host libthread_db library "/lib/tls/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 1096250656 (LWP 14425)]
[KCrash handler]
#9  0x41ea1056 in KJS::Identifier::remove () from /opt/kde3/lib/libkjs.so.1
#10 0x41ea3178 in KJS::UString::Rep::destroy () from /opt/kde3/lib/libkjs.so.1
#11 0x41ea44fe in KJS::UString::release () from /opt/kde3/lib/libkjs.so.1
#12 0x41ea48f0 in __tcf_25 () from /opt/kde3/lib/libkjs.so.1
#13 0x40f71820 in exit () from /lib/tls/libc.so.6
#14 0x0804e1fa in launch ()
#15 0x0804f08c in handle_launcher_request ()
#16 0x0804f649 in handle_requests ()
#17 0x0804fec1 in main ()