[Kde-java] Bug in KFileDialog
Richard Dale
kde-java@kde.org
Tue, 4 Mar 2003 20:12:48 +0000
It looks as though this crash is caused by the java runtime in the jvm linking
against a different version of libstdc++-libc6.x-x from the one kdelibs was
built against. Here is a topic called 'Topic: JNI problems with C++ RTTI on
Linux':
http://forum.java.sun.com/thread.jsp?forum=52&thread=138362
So you would need to compile kdelibs and the bindings with exactly the same
gcc compiler that was used to build the jvm and associated libs.
Compiling to native code with gcj wouldn't have this problem, it would only
affect binary only jvms.
-- Richard
On Wednesday 26 February 2003 11:42 pm, Felix Rodriguez wrote:
> The gcj sounds like the easier option for me. I'll try compiling my program
> under gcj to see if I still get the crash.
>
> To get the C++ stack trace I did the following.
>
> Dr Konqui always hangs but never gets the backtrace so I did a ps -A and I
> found the last java process id. Then I ran gdb and attached to the process
> id I got from ps. This generates a lot of verbage that you have to keep
> hitting enter through. Finally when you get back to the gdb prompt type
> backtrace.
>
> I hope this helps.
>
> On Wednesday 26 February 2003 05:42 pm, Richard Dale wrote:
> > On Wednesday 26 February 2003 1:39 pm, Felix Rodriguez wrote:
> > > Thanks for the help. For now I'll use QFileDialog in my code as a work
> > > around. Once this problem is resolved in the stable kde release, I'll
> > > change it back to KFileDialog. Thanks for the java bindings. I find the
> > > combination of java and Qt much easier to work with than C++ and Qt.
> >
> > Yes, perhaps using QFileDialog is the best thing to do for now. All this
> > trouble with dynamic_casts is a good example of why I don't like C++ much
> > either - the RTTI stuff seems bolted on as an afterthought.
> >
> > But if you can test the patch, and confirm it fixes the KFileDialog
> > problem and doesn't have any side effects and KDE 3.1 works normally,
> > that would be helpful with justifying the fix on the kde-core-devel list.
> >
> > Another work round might be to build the app with gcj and release it as
> > native code. If anyone can try a gcj compiled app with a getOpenFileName
> > dialog (eg KScribble), I would be very interested to know if it has the
> > dynamic_cast crash problem or not.
> >
> > BTW: how do you get a nice C++ stack trace of a crash with java - I
> > haven't been able to run java apps under gdb to do that?
> >
> >
> >
> > -- Richard
> >
> > > At 10:45 AM 2/26/2003 +0000, you wrote:
> > > >On Tuesday 25 February 2003 6:17 pm, Felix Rodriguez wrote:
> > > > > Thanks for the solution. I'll test it out on my system and see
> > > > > how it goes.
> > > >
> > > >Oops - I've just found I've got some of the files round the wrong way
> > > > in the patch sorry - please find a second patch attached.
> > > >
> > > > > I am planning on releasing my program to the general public so I am
> > > > > wondering whether your patch will make it to the next version of
> > > > > kdelibs. Have you contacted the KDE maintainers about this problem?
> > > >
> > > >Yes, I'll mail the kde-core-devl list when I've done some more
> > > >investigation -
> > > >it's pretty much a 'showstopper' if you can't open and save files in a
> > > > KDE java app. You have a very recent gcc, and I have an old gcc 2.95
> > > > version so it seems to affect all compiler versions. I had a similar
> > > > problem with a dynamic_cast about a year ago in the KStyle code, but
> > > > that was just one of them in a single source file. This time nearly
> > > > all (or possibly all) of the casts don't seem to be working with
> > > > java.
> > > >
> > > >There are still dynamic_casts that can't be converted to qt_casts
> > > > because the target of the cast wasn't a QObject - we need to find if
> > > > those are going to be a problem. And I'm not sure if all
> > > > dynamic_casts in kdelibs crash in a java app, or just some of them
> > > > yet.
> > > >
> > > >-- Richard
> > > >
> > > > > At 05:27 PM 2/25/2003 +0000, you wrote:
> > > > > >I've written a sed script to convert as many dynamic_casts in
> > > > > > kdelibs as possible to qt_cast()'s by doing this sort of thing:
> > > > > >
> > > > > >cd kdelibs/kdeui
> > > > > >FILES="ktoolbarhandler.cpp ktoolbar.cpp kcursor.cpp kaction.cpp
> > > > > > kcombobox.cpp" rm -f tmp
> > > > > >mkdir tmp save
> > > > > >for FILE in $FILES ; do
> > > > > >cp $FILES save
> > > > > >cat $FILE | sed -e 's/dynamic_cast<\([^\* ]*\) *\*>(\(.*()\)
> > > > > > *)/(\2 == 0 ? 0 :
> > > > > >(\1 *) (\2)->qt_cast("\1"))/' \
> > > > > > -e 's/dynamic_cast<\([^\* ]*\) *\*>(\(.*\) *)/(\2 == 0 ? 0 : (\1
> > > > > > *) (\2)->qt_cast("\1"))/' > tmp/$FILE
> > > > > > done
> > > > > > cp tmp/*.cpp .
> > > > > >
> > > > > >But to save doing all that, please find attached a patch for the
> > > > > > KDE 3.1 kdelibs. Copy the patch to the directory above kdelibs,
> > > > > > then
> > > > > >
> > > > > >$ cd kdelibs
> > > > > >$ patch -p1 < ../kdelibs_3_1_dyn_to_qt_cast.patch
> > > > > >$ make
> > > > > >$ su -c'make install'
> > > > > >
> > > > > >Not all dynamic_casts could be converted because the target wasn't
> > > > > > an instance
> > > > > >of a QObject. However, after the patch the java
> > > > > > KFileDialog.getOpenFileName() method should work correctly..
> > > > > >
> > > > > >-- Richard
> > > > > >
> > > > > >On Tuesday 25 February 2003 11:36 am, Richard Dale wrote:
> > > > > > > On Sunday 23 February 2003 11:31 pm, Felix Rodriguez wrote:
> > > > > > > > I think I might have discovered a bug in the KFileDialog
> > > > > > > > getOpenFileName method. I am using QFileDialog instead and
> > > > > > > > this seems to be working fine. KFileDialog is supposed to be
> > > > > > > > a dropin replacement for QFileDialog.
> > > > > > >
> > > > > > > The problem is that dynamic casts don't appear to work properly
> > > > > > > when kdelibs is linked with a java app. I changed four dynamic
> > > > > > > casts in the dialog code to use qt_cast() instead and that
> > > > > > > worked (eg one in KComboBox::setLineEdit() caused the crash
> > > > > > > below).
> > > > > > >
> > > > > > > But when the code got as far as displaying the dialog, it
> > > > > > > crashed in the QDialog::exec() call to handle the modal dialog.
> > > > > > > I would expect QFileDialog to also use the exec() method, so
> > > > > > > I've no idea why that works fine.
> > > > > > >
> > > > > > > I'm using gcc 2.95 and glibc 2.2.5, I don't know if a newer
> > > > > > > compiler and associated libs would work ok - which version are
> > > > > > > you using? Perhaps if the app was compiled with gcj, rather
> > > > > > > than run under a jvm, it might work properly.
> > > > > > >
> > > > > > > However, I couldn't switch from gcc 2.95 to gcc 3.2.2 to use
> > > > > > > gcj because dynamic casts appeared to be crashing when I built
> > > > > > > KDE with it, and KDE wouldn't start properly - and that was
> > > > > > > nothing to do with java. So I'm feeling a bit stuck at the
> > > > > > > moment..
> > > > > > >
> > > > > > > -- Richard
> > > > > > >
> > > > > > > > Here is the backtrace that is generated from gdb.
> > > > > > > >
> > > > > > > > #0 0x40511829 in wait4 () from /lib/libc.so.6
> > > > > > > > #1 0x4058da24 in __DTOR_END__ () from /lib/libc.so.6
> > > > > > > > #2 0x400308e3 in waitpid () from /lib/libpthread.so.0
> > > > > > > > #3 0x4c93401e in KCrash::defaultCrashHandler(int) ()
> > > > > > > > from /usr/kde/3.1/lib/libkdecore.so.4
> > > > > > > > #4 <signal handler called>
> > > > > > > > #5 0x0820e610 in ?? ()
> > > > > > > > #6 0x4c77e52b in KComboBox::setLineEdit(QLineEdit*) ()
> > > > > > > > from /usr/kde/3.1/lib/libkdeui.so.4
> > > > > > > > #7 0x4c77d93d in KComboBox::KComboBox(bool, QWidget*, char
> > > > > > > > const*) () from /usr/kde/3.1/lib/libkdeui.so.4
> > > > > > > > #8 0x4c50c91b in
> > > > > > > > KURLComboBox::KURLComboBox(KURLComboBox::Mode, bool,
> > > > > > > > QWidget*, char const*) () from /usr/kde/3.1/lib/libkio.so.4
> > > > > > > > #9 0x4c4ed880 in KFileDialog::init(QString const&, QString
> > > > > > > > const&, QWidget*) () from /usr/kde/3.1/lib/libkio.so.4 #10
> > > > > > > > 0x4c4f1dd0 in KFileDialog::getOpenFileName(QString const&,
> > > > > > > > QString const&, QWidget*, QString const&) () from
> > > > > > > > /usr/kde/3.1/lib/libkio.so.4 #11 0x4be1b3c0 in
> > > > > > > > Java_org_kde_koala_KFileDialog_getOpenFileName__Ljava_lang_St
> > > > > > > >ri ng _2Lj ava_ la
> > > > > > > > ng_String_2Lorg_kde_qt_QWidget_2Ljava_lang_String_2 () from
> > > > > > > > /usr/kde/3.1/lib/libkdejava.so.1.0.0
> > > > > > > > #12 0x0806254d in ?? ()
> > > > > > > > #13 0x0805fb29 in ?? ()
> > > > > > > > #14 0x4045a9de in StubRoutines::_code1 ()
> > > > > > > >
> > > > > > > > _______________________________________________
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> > > > > > > > http://mail.kde.org/mailman/listinfo/kde-java
> > > > > > >
> > > > > > > _______________________________________________
> > > > > > > Kde-java mailing list
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> > > > >
> > > > > Felix Rodriguez
> > > > > Programmer Analyst
> > > > > Phone: 860-685-3984
> > > > > Email: frodriguez@mail.wesleyan.edu
> > > > >
> > > > >
> > > > > _______________________________________________
> > > > > Kde-java mailing list
> > > > > Kde-java@mail.kde.org
> > > > > http://mail.kde.org/mailman/listinfo/kde-java
> > >
> > > Felix Rodriguez
> > > Programmer Analyst
> > > Phone: 860-685-3984
> > > Email: frodriguez@mail.wesleyan.edu
> > >
> > >
> > > _______________________________________________
> > > Kde-java mailing list
> > > Kde-java@mail.kde.org
> > > http://mail.kde.org/mailman/listinfo/kde-java
> >
> > _______________________________________________
> > Kde-java mailing list
> > Kde-java@mail.kde.org
> > http://mail.kde.org/mailman/listinfo/kde-java
>
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