[Kde-bindings] [Bug 108650] memory leak in qtruby? (Qt::Socket)

[Richard Dale]

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http://bugs.kde.org/show_bug.cgi?id=108650         




------- Additional Comments From Richard_Dale tipitina demon co uk  2005-07-08 14:45 -------
On Wednesday 06 July 2005 14:42, Caleb Tennis wrote:
[bugs.kde.org quoted mail]
Yes, you're right there is a leak for QString value return types. When a Smoke 
method returns a QString, it creates a new temporary QString with 'new', but 
never deletes it. I also tried 'QString*' and 'QString&' return types with 
readLine(), and those don't create a temporary string.


    virtual      QString readLine();

Generates this code:
   void x_45(Smoke::Stack x) {
        // readLine()
        QString xret = this->QSocket::readLine();
        x[0].s_voidp = (void*)new QString(xret);
    }


    virtual      QString * readLine(); Becomes

Generates this code:
    void x_45(Smoke::Stack x) {
        // readLine()
        QString* xret = this->QSocket::readLine();
        x[0].s_voidp = (void*)xret;
    }


    virtual      QString & readLine();

Generates this code:
    void x_45(Smoke::Stack x) {
        // readLine()
        QString& xret = this->QSocket::readLine();
        x[0].s_voidp = (void*)&xret;
    }

In Qt.cpp, the class to handle a return value has a boolean method called 
cleanup(), which is false.

class MethodReturnValue : public Marshall {
...

    bool cleanup() { return false; }
};

In handlers.cpp, the code to marshall a QString to a ruby string will only 
delete the QString if cleanup() is true:

case Marshall::ToVALUE:
{
    QString *s = (QString*)m->item().s_voidp;
    if(s) {
        if (s->isNull()) {
            *(m->var()) = Qnil;
        } else {
            *(m->var()) = rstringFromQString(s);
        }
        if(m->cleanup())
            delete s;
    } else {
            *(m->var()) = Qnil;
    }
}

So the temporary QString from the 'QString readLine()' version of the method 
is never deleted. Either cleanup() should return true in MethodReturnValue, 
or the marshalling code should check if the QString is a value type and only 
delete it if it is. 

I looked at the PerlQt code in PerlQt-3.009 beta and it's just the same, and 
will have this leak too.

-- Richard