Service/APT: Return proper parameters in GetLockHandle.

Documented some APT functions
This allows applets to boot.

src/core/hle/applets/applet.cpp

@@ -89,12 +89,21 @@ ResultCode Applet::Start(const Service::APT::AppletStartupParameter& parameter)
     return result;
 }
 
+bool IsLibraryAppletRunning() {
+    // Check the applets map for instances of any applet
+    for (auto& itr = applets.begin(); itr != applets.end(); ++itr)
+        if (itr->second != nullptr)
+            return true;
+    return false;
+}
+
 void Init() {
     // Register the applet update callback
     applet_update_event = CoreTiming::RegisterEvent("HLE Applet Update Event", AppletUpdateEvent);
 }
 
 void Shutdown() {
+    CoreTiming::RemoveEvent(applet_update_event);
 }
 
 }

src/core/hle/applets/applet.h

@@ -67,6 +67,9 @@ protected:
     Service::APT::AppletId id; ///< Id of this Applet
 };
 
+/// Returns whether a library applet is currently running
+bool IsLibraryAppletRunning();
+
 /// Initializes the HLE applets
 void Init();
 

src/core/hle/service/apt/apt.cpp

@@ -101,18 +101,19 @@ void NotifyToWait(Service::Interface* self) {
 
 void GetLockHandle(Service::Interface* self) {
     u32* cmd_buff = Kernel::GetCommandBuffer();
-    u32 flags = cmd_buff[1]; // TODO(bunnei): Figure out the purpose of the flag field
+    // Bits [0:2] are the applet type (System, Library, etc)
+    // Bit 5 tells the application that there's a pending APT parameter,
+    // this will cause the app to wait until parameter_event is signaled.
+    u32 applet_attributes = cmd_buff[1];
 
     cmd_buff[1] = RESULT_SUCCESS.raw; // No error
 
-    // Not sure what these parameters are used for, but retail apps check that they are 0 after
-    // GetLockHandle has been called.
-    cmd_buff[2] = 0; // Applet Attributes, this value is passed to Enable.
-    cmd_buff[3] = 0;
-    cmd_buff[4] = 0;
-
+    cmd_buff[2] = applet_attributes; // Applet Attributes, this value is passed to Enable.
+    cmd_buff[3] = 0; // Least significant bit = power button state
+    cmd_buff[4] = IPC::CopyHandleDesc();
     cmd_buff[5] = Kernel::g_handle_table.Create(lock).MoveFrom();
-    LOG_TRACE(Service_APT, "called handle=0x%08X", cmd_buff[5]);
+
+    LOG_WARNING(Service_APT, "(STUBBED) called handle=0x%08X applet_attributes=0x%08X", cmd_buff[5], applet_attributes);
 }
 
 void Enable(Service::Interface* self) {
@@ -139,13 +140,16 @@ void IsRegistered(Service::Interface* self) {
     u32* cmd_buff = Kernel::GetCommandBuffer();
     u32 app_id = cmd_buff[1];
     cmd_buff[1] = RESULT_SUCCESS.raw; // No error
-    /// TODO(Subv): It is currently unknown what this value (0x400) means,
-    /// but i believe it is used as a global "LibraryApplet" id, to verify if there's
-    /// any LibApplet currently running. This is not verified.
-    if (app_id != 0x400)
+
+    // TODO(Subv): An application is considered "registered" if it has already called APT::Enable
+    // handle this properly once we implement multiprocess support.
+    cmd_buff[2] = 0; // Set to not registered by default
+
+    if (app_id == static_cast<u32>(AppletId::AnyLibraryApplet)) {
+        cmd_buff[2] = HLE::Applets::IsLibraryAppletRunning() ? 1 : 0;
+    } else if (auto applet = HLE::Applets::Applet::Get(static_cast<AppletId>(app_id))) {
         cmd_buff[2] = 1; // Set to registered
-    else
-        cmd_buff[2] = 0; // Set to not registered
+    }
     LOG_WARNING(Service_APT, "(STUBBED) called app_id=0x%08X", app_id);
 }
 

src/core/hle/service/apt/apt.h

@@ -62,6 +62,7 @@ enum class AppletId : u32 {
     Extrapad           = 0x208,
     Memolib            = 0x209,
     Application        = 0x300,
+    AnyLibraryApplet   = 0x400,
     SoftwareKeyboard2  = 0x401,
 };
 
@@ -96,8 +97,26 @@ void GetSharedFont(Service::Interface* self);
  */
 void NotifyToWait(Service::Interface* self);
 
+/**
+ * APT::GetLockHandle service function
+ *  Inputs:
+ *      1 : Applet attributes
+ *  Outputs:
+ *      1 : Result of function, 0 on success, otherwise error code
+ *      2 : Applet attributes
+ *      3 : Power button state
+ *      4 : IPC handle descriptor
+ *      5 : APT mutex handle
+ */
 void GetLockHandle(Service::Interface* self);
 
+/**
+ * APT::Enable service function
+ *  Inputs:
+ *      1 : Applet attributes
+ *  Outputs:
+ *      1 : Result of function, 0 on success, otherwise error code
+ */
 void Enable(Service::Interface* self);
 
 /**