Re: JNI assertion failure

[Dalibor Topic]

Archie Cobbs wrote:
> Archie Cobbs wrote:
>
> > > With Classpath 0.16, trying to run a very simple Swing demo under JCVM,
> > > I get a JNI assertion failure in a call to GetIntField(), because the 
> > > object
> > > type and the fieldID are not compatible:
> > >
> > >    gnu/java/awt/peer/gtk/address@hidden not instance of 
> > > gnu/java/awt/peer/gtk/GtkGenericPeer
> > >
> > > Here is the relevant stack trace snippet:
> > >
> > > #7  0x29f862d7 in 
> > > Java_gnu_java_awt_peer_gtk_GdkGraphics_initState__Lgnu_java_awt_peer_gtk_GtkComponentPeer_2 
> > > (env=0x107ed6a0, obj=0x29795698, peer=0x2979569c)
> > >     at gnu_java_awt_peer_gtk_GdkGraphics.c:154
> >
> >
> > Hmm, no response.. can anyone else confirm this problem??
> >
> > It looks like this code is completely broken, because
> > it's trying to save a pointer in a field that doesn't
> > exist. Line 154 of gnu_java_awt_peer_gtk_GdkGraphics.c says:
> >
> >   NSA_SET_PTR (env, obj, g)
> >
> > but "obj" is a gnu/java/awt/peer/gtk/GdkGraphics object, not
> > a gnu/java/awt/peer/gtk/GtkGenericPeer object, the class that
> > contains the "native_state" field.
>
>
> Since nobody seems to be listening, I'm going to check in the
> attached patch. This will cause all programs that use the GTK
> peer to crash with an assertion failure. Sorry! The code
> is broken but I don't know how to fix it. At least now we get
> an assertion failure instead of random memory corruption.
>
> You have been warned :-)

Heh. ;)

> +  assert ((*env)->IsAssignableFrom(env,
> +    (*env)->GetObjectClass(env, obj), table->clazz));
> +
>    obj_id = (*env)->GetIntField (env, obj, table->hash);

Doesn't GetObjectClass change the state of env? If that's the case, it 
maybe shouldn't be an assert.

cheers,
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