Hi,

I am new to Qt world. I am using Qt4.4.3 on linux/X11 system and I have taken the opensource Qt/X11 version
I had a product which was running in Qt3.3 and I am trying to port it to Qt4. I have modified so as of now it does not give any compilation error in Qt4. But, while trying to run the application, I am getting SEGV and the gdb shows the problem emantes from exec() call
I also tried with debug version of qt but same result.
Here's what I see in gdb

QtApplication::exec()

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 107215760 (LWP 7346)]
0x06f107be in QString::fromLocal8Bit (
str=0x2d322e31 <Address 0x2d322e31 out of bounds>, size=-1)
at tools/qstring.cpp:3363
3363 if (size == 0 || (!*str && size < 0))
Current language: auto; currently c++
(gdb) bt
#0 0x06f107be in QString::fromLocal8Bit (
str=0x2d322e31 <Address 0x2d322e31 out of bounds>, size=-1)
at tools/qstring.cpp:3363
#1 0x06fcca12 in QCoreApplication::arguments ()
at kernel/qcoreapplication.cpp:1849
#2 0x053a5e95 in sm_performSaveYourself (smd=0x87467e8)
at kernel/qapplication_x11.cpp:5078
#3 0x053a683b in sm_saveYourselfCallback (smcConn=0x8747460,
clientData=0x87467e8, saveType=1, shutdown=0, interactStyle=0)
at kernel/qapplication_x11.cpp:5061
#4 0x004b351f in _SmcProcessMessage () from /usr/lib/libSM.so.6
#5 0x004c90a9 in IceProcessMessages () from /usr/lib/libICE.so.6
#6 0x053a693e in QSmSocketReceiver::socketActivated (this=0x8749710)
at kernel/qapplication_x11.cpp:5200
#7 0x053a69af in QSmSocketReceiver::qt_metacall (this=0x8749710,
_c=QMetaObject::InvokeMetaMethod, _id=0, _a=0x663e920)
at .moc/debug-shared/qapplication_x11.moc:64
#8 0x06fe5507 in QMetaObject::activate (sender=0x87475a0,
from_signal_index=4, to_signal_index=4, argv=0x663e920)
at kernel/qobject.cpp:3022
#9 0x06fe5a91 in QMetaObject::activate (sender=0x87475a0, m=0x70d4a50,
local_signal_index=0, argv=0x663e920) at kernel/qobject.cpp:3092
#10 0x0702ece0 in QSocketNotifier::activated (this=0x87475a0, _t1=12)
---Type <return> to continue, or q <return> to quit---
at .moc/debug-shared/moc_qsocketnotifier.cpp:81
#11 0x06ff0709 in QSocketNotifier::event (this=0x87475a0, e=0x663ee3c)
at kernel/qsocketnotifier.cpp:320
#12 0x0532acff in QApplicationPrivate::notify_helper (this=0x8700038,
receiver=0x87475a0, e=0x663ee3c) at kernel/qapplication.cpp:3803
#13 0x0532b018 in QApplication::notify (this=0x871c6c0, receiver=0x87475a0,
e=0x663ee3c) at kernel/qapplication.cpp:3393
#14 0x06fce669 in QCoreApplication::notifyInternal (this=0x871c6c0,
receiver=0x87475a0, event=0x663ee3c) at kernel/qcoreapplication.cpp:587
#15 0x06fd2c93 in QCoreApplication::sendEvent (receiver=0x87475a0,
event=0x663ee3c)
at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:209
#16 0x07003dce in socketNotifierSourceDispatch (source=0x872ceb8)
at kernel/qeventdispatcher_glib.cpp:105
#17 0x004147f2 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#18 0x004177cf in ?? () from /lib/libglib-2.0.so.0
#19 0x00417d35 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#20 0x07003578 in QEventDispatcherGlib:rocessEvents (this=0x86fc458,
flags=@0x663ef8c) at kernel/qeventdispatcher_glib.cpp:319
#21 0x053e7b58 in QGuiEventDispatcherGlib:rocessEvents (this=0x86fc458,
flags=@0x663efbc) at kernel/qguieventdispatcher_glib.cpp:198
#22 0x06fcab5e in QEventLoop:rocessEvents (this=0x663f040, flags=@0x663eff8)
at kernel/qeventloop.cpp:143
---Type <return> to continue, or q <return> to quit---
#23 0x06fcad9d in QEventLoop::exec (this=0x663f040, flags=@0x663f048)
at kernel/qeventloop.cpp:194
#24 0x06fcefa0 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:845
#25 0x0532a9fc in QApplication::exec () at kernel/qapplication.cpp:3331
#26 0x003bfaf4 in QtApplication::exec (this=0x871c6c0)
at ../../src/share/basis/native/awt/qt/QtApplication.cpp:75
#27 0x003be6c0 in Java_java_awt_QtGraphicsEnvironment_QTexec (env=0x87244fc,
self=0x870dacc) at ../../src/share/basis/native/awt/qt/QtBackEnd.cpp:975
#28 0x08154364 in args_done ()
at ../../src/x86/javavm/runtime/invokeNative_i386.S:201
#29 0x087244fc in ?? ()
#30 0x0870dacc in ?? ()
#31 0x082e8080 in ?? ()
#32 0x0870dad0 in ?? ()
#33 0x087244fc in ?? ()
#34 0x0663f118 in ?? ()
#35 0x080b024c in CVMinvokeJNIHelper (ee=0x87244fc, mb=0x3be690)
at ../../src/share/javavm/runtime/interpreter.c:4329
Backtrace stopped: frame did not save the PC

Here's what I do before exec()
1. I create QApplication(argc, argv) where argc = 1, argv={"cvm", "-qws", NULL}; //where qws was used for embedded qt but since I use the product in Qt/X11 I use argc=1 so qws will not be passed
The code is like this:

bool
QtScreen::init()
{
printf("QtScreen::init()\n");
if ( qtApp != NULL )
return TRUE; // already initialized

/*
* We need to create an array of size 3 because the QApplication assigns a
* NULL pointer to the argv[argc] position after it processes and removes
* all the Qt command line options from the argv vector. This is a Qt bug
* to write past the end of the argv vector. Qt also keeps a refernece
* to argv,
* so it shouldn't go away.
*/

int argc = 1;
char ** argv = this->getArgs(&argc);

/*
* Create a QApplication
*/
new QtApplication(argc, argv);
QRect screen_bounds = QApplication::desktop()->frameGeometry();
/*
* Create the Qt widget that backs the Window
*/
printf("createQtWindow called\n");
this->createQtWindow();
assert(this->m_window != NULL);

AWT_QT_LOCK;
#ifdef QT_VER_4
qtApp->setActiveWindow(this->m_window);
#else
qtApp->setMainWidget(this->m_window);
#endif

AWT_QT_UNLOCK;

return TRUE ;
}

QtScreen::getArgs(int *argc) {
printf("QtScreen::getArgs()\n");
int count;
// Use the "-sync" flag to force Xlib calls to be synchronous, which
// would aid in debugging Xlib async errors.

static char *argv[] = {"cvm", "-qws", NULL};

count = 1;

#ifdef QWS
#ifndef QTOPIA
// If environment varible QWS_CLIENT is not defined,
// assume we are running as the server (in the qt-embedded sense).
if (getenv("QWS_CLIENT") == NULL) {
count++;
}
#endif /* QTOPIA */
#endif /* QWS */

*argc = count;

return (char **)&argv;
}

void
QtScreen::createQtWindow() {
printf("QtScreen::createQtWindow()\n");
AWT_QT_LOCK;
this->m_window = new QtWindow(Qt::FramelessWindowHint|Qt::Window);
QBitmap bitmap(this->m_width, this->m_height);
AWT_QT_UNLOCK;
this->m_window->setMask(bitmap);
}

#ifdef QT_VER_4
QtWindow::QtWindow(int flags, const char *name, QWidget *parent) :
QWidget( parent, (Qt::WindowFlags)flags)
#else
QtWindow::QtWindow(int flags, const char *name, QWidget *parent) :
QWidget( parent, name, (WFlags)flags)
#endif
{
printf("QtWindow::QtWindow %d %s, %u\n", flags, name,parent);
// install event filter...?
// If mouse tracking is true, then mouseMoveEvent is called
// whenever the mouse moved, even if button isn't held down.
//AWT_QT_LOCK;
setMouseTracking(TRUE);
//AWT_QT_UNLOCK;
transMask = NULL;
printf("QtWindow constructor returned\n");
}

Once init() calls returns, we call exec() as in
int
QtApplication::exec(void) {
printf("QtApplication::exec()\n");
#if 0 // 6207033
printf("*** QtApplication.exec(tid=%x) ***\n",
(int)AWT_QT_CURRENT_THREAD()) ;
#endif
m_is_event_loop_started = TRUE ;
int ret = NORMAL_EXIT_CODE;

#ifdef QT_THREAD_SUPPORT
ret = QAPPLICATION_CLASS::exec() ;
printf("exec done\n");
#else
printf("QtApplication::QtApplication() no QT_THREAD_SUPPORT\n");
QtCondVar timer ;
timer.mutex()->lock();
while ( !m_shutdown ) { // 6176847:Loop till we shutdown.
AWT_QT_LOCK;
this->processEvents(0);
AWT_QT_UNLOCK;
/* sleep for some time */
timer.wait(100) ;
}
// 6176847: set the return code to simulate the same behavior as
// exec() return value.
ret = SHUTDOWN_EXIT_CODE;
#endif /* QT_THREAD_SUPPORT */

We have QT_THREAD_SUPPORT defined
Cananyone please help me? I am stuck with this problem