From 7e2903cb74050d846f2da951dff7e84aee13761b Mon Sep 17 00:00:00 2001
From: Yuri Kunde Schlesner
Date: Sun, 21 Dec 2014 10:04:08 -0200
Subject: 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 | 118 +++++++++++++++++++++++------------------
 1 file changed, 67 insertions(+), 51 deletions(-)

(limited to 'src/core/hle/kernel/kernel.cpp')

diff --git a/src/core/hle/kernel/kernel.cpp b/src/core/hle/kernel/kernel.cpp
index e8bf83a44..e59ed1b57 100644
--- a/src/core/hle/kernel/kernel.cpp
+++ b/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;
-    }
-    if (next_id >= range_bottom && next_id < range_top) {
-        range_bottom = next_id++;
-    }
-    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;
-        }
+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;
     }
-    LOG_ERROR(Kernel, "Unable to allocate kernel object, too many objects slots in use.");
-    return 0;
-}
+    next_free_slot = generations[slot];
 
-bool HandleTable::IsValid(Handle handle) const {
-    int index = handle - HANDLE_OFFSET;
-    if (index < 0)
-        return false;
-    if (index >= MAX_COUNT)
-        return false;
+    u16 generation = next_generation++;
 
-    return occupied[index];
+    // 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);
 }
 
-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;
+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;
     }
-    pool.fill(nullptr);
-    next_id = INITIAL_NEXT_ID;
+    return Create(object);
 }
 
-Object* &HandleTable::operator [](Handle handle)
-{
-    _dbg_assert_msg_(Kernel, IsValid(handle), "GRABBING UNALLOCED KERNEL OBJ");
-    return pool[handle - HANDLE_OFFSET];
+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;
 }
 
-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());
-            }
-        }
-    }
+bool HandleTable::IsValid(Handle handle) const {
+    size_t slot = GetSlot(handle);
+    u16 generation = GetGeneration(handle);
+
+    return slot < MAX_COUNT && objects[slot] != nullptr && generations[slot] == generation;
 }
 
-int HandleTable::GetCount() const {
-    return std::count(occupied.begin(), occupied.end(), true);
+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)];
 }
 
-Object* HandleTable::CreateByIDType(int type) {
-    LOG_ERROR(Kernel, "Unimplemented: %d.", type);
-    return nullptr;
+void HandleTable::Clear() {
+    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;
+    }
+    next_free_slot = 0;
 }
 
 /// Initialize the kernel
-- 
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