[Core] Add callback when the BinaryDataNotification is unregistered

Useful when you want to destroy the notification handler object once the owned view is destroyed.

Because this is used to destroy the object, it might be more useful to call it that, although the lifetime of the
notification handler object when passed to the core is quite obscure.

Author: emesare

binaryninjaapi.h

@@ -4086,6 +4086,7 @@ namespace BinaryNinja {
 	  private:
 		BNBinaryDataNotification m_callbacks;
 
+		static void UnregisteredCallback(void* ctxt);
 		static uint64_t NotificationBarrierCallback(void* ctxt, BNBinaryView* object);
 		static void DataWrittenCallback(void* ctxt, BNBinaryView* data, uint64_t offset, size_t len);
 		static void DataInsertedCallback(void* ctxt, BNBinaryView* data, uint64_t offset, size_t len);
@@ -4244,6 +4245,7 @@ namespace BinaryNinja {
 
 		BNBinaryDataNotification* GetCallbacks() { return &m_callbacks; }
 
+		virtual void OnUnregistered() {}
 		virtual uint64_t OnNotificationBarrier(BinaryView* view)
 		{
 			(void)view;

binaryninjacore.h

@@ -37,14 +37,14 @@
 // Current ABI version for linking to the core. This is incremented any time
 // there are changes to the API that affect linking, including new functions,
 // new types, or modifications to existing functions or types.
-#define BN_CURRENT_CORE_ABI_VERSION 162
+#define BN_CURRENT_CORE_ABI_VERSION 163
 
 // Minimum ABI version that is supported for loading of plugins. Plugins that
 // are linked to an ABI version less than this will not be able to load and
 // will require rebuilding. The minimum version is increased when there are
 // incompatible changes that break binary compatibility, such as changes to
 // existing types or functions.
-#define BN_MINIMUM_CORE_ABI_VERSION 161
+#define BN_MINIMUM_CORE_ABI_VERSION 163
 
 #ifdef __GNUC__
 	#ifdef BINARYNINJACORE_LIBRARY
@@ -1732,7 +1732,8 @@ extern "C"
 	typedef struct BNBinaryDataNotification
 	{
 		void* context;
-		uint64_t (*notificationBarrier)(void*ctxt, BNBinaryView* view);
+		void (*unregistered)(void* ctxt);
+		uint64_t (*notificationBarrier)(void* ctxt, BNBinaryView* view);
 		void (*dataWritten)(void* ctxt, BNBinaryView* view, uint64_t offset, size_t len);
 		void (*dataInserted)(void* ctxt, BNBinaryView* view, uint64_t offset, size_t len);
 		void (*dataRemoved)(void* ctxt, BNBinaryView* view, uint64_t offset, uint64_t len);

binaryview.cpp

@@ -38,6 +38,13 @@ struct SymbolQueueAddContext
 };
 
 
+void BinaryDataNotification::UnregisteredCallback(void* ctxt)
+{
+	BinaryDataNotification* notify = (BinaryDataNotification*)ctxt;
+	return notify->OnUnregistered();
+}
+
+
 uint64_t BinaryDataNotification::NotificationBarrierCallback(void* ctxt, BNBinaryView* object)
 {
 	BinaryDataNotification* notify = (BinaryDataNotification*)ctxt;
@@ -551,6 +558,7 @@ void BinaryDataNotification::RebasedCallback(void *ctxt, BNBinaryView *oldView,
 BinaryDataNotification::BinaryDataNotification()
 {
 	m_callbacks.context = this;
+	m_callbacks.unregistered = UnregisteredCallback;
 	m_callbacks.notificationBarrier = nullptr;
 	m_callbacks.dataWritten = DataWrittenCallback;
 	m_callbacks.dataInserted = DataInsertedCallback;
@@ -612,6 +620,7 @@ BinaryDataNotification::BinaryDataNotification()
 BinaryDataNotification::BinaryDataNotification(NotificationTypes notifications)
 {
 	m_callbacks.context = this;
+	m_callbacks.unregistered = UnregisteredCallback;
 	m_callbacks.notificationBarrier = (notifications & NotificationType::NotificationBarrier) ? NotificationBarrierCallback : nullptr;
 	m_callbacks.dataWritten = (notifications & NotificationType::DataWritten) ? DataWrittenCallback : nullptr;
 	m_callbacks.dataInserted = (notifications & NotificationType::DataInserted) ? DataInsertedCallback : nullptr;