Kernel: New handle manager

This handle manager more closely mirrors the behaviour of the CTR-OS
one. In addition object ref-counts and support for DuplicateHandle have
been added.

Note that support for DuplicateHandle is still experimental, since parts
of the kernel still use Handles internally, which will likely cause
troubles if two different handles to the same object are used to e.g.
wait on a synchronization primitive.

src/core/hle/kernel/kernel.cpp

@@ -17,73 +17,89 @@ HandleTable g_handle_table;
 u64 g_program_id = 0;
 
 HandleTable::HandleTable() {
-    next_id = INITIAL_NEXT_ID;
+    next_generation = 1;
+    Clear();
 }
 
-Handle HandleTable::Create(Object* obj, int range_bottom, int range_top) {
-    if (range_top > MAX_COUNT) {
-        range_top = MAX_COUNT;
+ResultVal<Handle> HandleTable::Create(Object* obj) {
+    _dbg_assert_(Kernel, obj != nullptr);
+
+    u16 slot = next_free_slot;
+    if (slot >= generations.size()) {
+        LOG_ERROR(Kernel, "Unable to allocate Handle, too many slots in use.");
+        return ERR_OUT_OF_HANDLES;
     }
-    if (next_id >= range_bottom && next_id < range_top) {
-        range_bottom = next_id++;
+    next_free_slot = generations[slot];
+
+    u16 generation = next_generation++;
+
+    // Overflow count so it fits in the 15 bits dedicated to the generation in the handle.
+    // CTR-OS doesn't use generation 0, so skip straight to 1.
+    if (next_generation >= (1 << 15)) next_generation = 1;
+
+    generations[slot] = generation;
+    intrusive_ptr_add_ref(obj);
+    objects[slot] = obj;
+
+    Handle handle = generation | (slot << 15);
+    obj->handle = handle;
+    return MakeResult<Handle>(handle);
+}
+
+ResultVal<Handle> HandleTable::Duplicate(Handle handle) {
+    Object* object = GetGeneric(handle);
+    if (object == nullptr) {
+        LOG_ERROR(Kernel, "Tried to duplicate invalid handle: %08X", handle);
+        return ERR_INVALID_HANDLE;
     }
-    for (int i = range_bottom; i < range_top; i++) {
-        if (!occupied[i]) {
-            occupied[i] = true;
-            pool[i] = obj;
-            pool[i]->handle = i + HANDLE_OFFSET;
-            return i + HANDLE_OFFSET;
-        }
-    }
-    LOG_ERROR(Kernel, "Unable to allocate kernel object, too many objects slots in use.");
-    return 0;
+    return Create(object);
+}
+
+ResultCode HandleTable::Close(Handle handle) {
+    if (!IsValid(handle))
+        return ERR_INVALID_HANDLE;
+
+    size_t slot = GetSlot(handle);
+    u16 generation = GetGeneration(handle);
+
+    intrusive_ptr_release(objects[slot]);
+    objects[slot] = nullptr;
+
+    generations[generation] = next_free_slot;
+    next_free_slot = slot;
+    return RESULT_SUCCESS;
 }
 
 bool HandleTable::IsValid(Handle handle) const {
-    int index = handle - HANDLE_OFFSET;
-    if (index < 0)
-        return false;
-    if (index >= MAX_COUNT)
-        return false;
+    size_t slot = GetSlot(handle);
+    u16 generation = GetGeneration(handle);
 
-    return occupied[index];
+    return slot < MAX_COUNT && objects[slot] != nullptr && generations[slot] == generation;
+}
+
+Object* HandleTable::GetGeneric(Handle handle) const {
+    if (handle == CurrentThread) {
+        // TODO(yuriks) Directly return the pointer once this is possible.
+        handle = GetCurrentThreadHandle();
+    } else if (handle == CurrentProcess) {
+        LOG_ERROR(Kernel, "Current process (%08X) pseudo-handle not supported", CurrentProcess);
+        return nullptr;
+    }
+
+    if (!IsValid(handle)) {
+        return nullptr;
+    }
+    return objects[GetSlot(handle)];
 }
 
 void HandleTable::Clear() {
-    for (int i = 0; i < MAX_COUNT; i++) {
-        //brutally clear everything, no validation
-        if (occupied[i])
-            delete pool[i];
-        occupied[i] = false;
+    for (size_t i = 0; i < MAX_COUNT; ++i) {
+        generations[i] = i + 1;
+        if (objects[i] != nullptr)
+            intrusive_ptr_release(objects[i]);
+        objects[i] = nullptr;
     }
-    pool.fill(nullptr);
-    next_id = INITIAL_NEXT_ID;
-}
-
-Object* &HandleTable::operator [](Handle handle)
-{
-    _dbg_assert_msg_(Kernel, IsValid(handle), "GRABBING UNALLOCED KERNEL OBJ");
-    return pool[handle - HANDLE_OFFSET];
-}
-
-void HandleTable::List() {
-    for (int i = 0; i < MAX_COUNT; i++) {
-        if (occupied[i]) {
-            if (pool[i]) {
-                LOG_DEBUG(Kernel, "KO %i: %s \"%s\"", i + HANDLE_OFFSET, pool[i]->GetTypeName().c_str(),
-                    pool[i]->GetName().c_str());
-            }
-        }
-    }
-}
-
-int HandleTable::GetCount() const {
-    return std::count(occupied.begin(), occupied.end(), true);
-}
-
-Object* HandleTable::CreateByIDType(int type) {
-    LOG_ERROR(Kernel, "Unimplemented: %d.", type);
-    return nullptr;
+    next_free_slot = 0;
 }
 
 /// Initialize the kernel