CODEWITHSUNDEEP
kotlinkotlin-multiplatformkotlin-native
TheGreedy
TheGreedy

Reputation: 11

Kotlin Native Pointer initialization

I have a little bit of a fight with Kotlin Native and the runtime. In short: I am building a jvmti agent, linking a dynamic library.

Now I have following case, what I like to achieve can be expressed in C like:

char* class_sig; 
(*jvmti)->GetClassSignature(object_klass, &class_sig, NULL) 
do something with class_sig.... 
(*jvmti)->Deallocate((unsigned char*) class_sig);

So in that case the jvmti environment allocates the memory for class_sig, that is why I have to deallocate through the jvmti environment.

How can this be achieved in Kotlin? I am a little on the fence regarding calling nativeheap.alloc, wouldn't that cause a memory leak because the jvmti environment already allocates memory?

Or can I just do:

val signaturePtr = nativeHeap.alloc<CPointerVar<ByteVar>>()
        
jvmti?.pointed?.pointed?.GetClassSignature?.invoke(jvmti, klass, signaturePtr.ptr, null)

Call jvmti dealloc?

Upvotes: 1

Views: 432

Answers (1)

Evgeny K
Evgeny K

Reputation: 3177

Kotlin Native way is to use memScoped blocks for such task. Take a look at official guide for C interop

If you write

memScoped {
    val signaturePtr = alloc<CPointerVar<ByteVar>>()
    //...
}

Kotlin will take care of memory deallocation inside memScoped block, no need to invoke jmti Deallocate

Upvotes: 0

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