From b343cf9bb73555bb2ec119d428ad86ec762348c8 Mon Sep 17 00:00:00 2001
From: Johanna Amann <johanna@corelight.com>
Date: Mon, 13 Jan 2020 15:28:56 -0800
Subject: [PATCH] &on_change working for removals from tables.

Insertions and changes are still noops.
---
 src/Val.cc | 70 ++++++++++++++++++++++++++++++++++++++++++++++++------
 src/Val.h  | 14 +++++++----
 2 files changed, 73 insertions(+), 11 deletions(-)

diff --git a/src/Val.cc b/src/Val.cc
index 7f38c8f3fa..46e8f68766 100644
--- a/src/Val.cc
+++ b/src/Val.cc
@@ -1927,16 +1927,61 @@ ListVal* TableVal::RecoverIndex(const HashKey* k) const
 	return table_hash->RecoverVals(k);
 	}
 
+void TableVal::CallChangeFunc(const Val* index, Val* old_value, OnChangeType tpe)
+	{
+	if ( ! change_func )
+		{
+		Unref(old_value);
+		return;
+		}
+
+	try
+		{
+		Val* thefunc = change_func->Eval(0);
+
+		if ( ! thefunc )
+			{
+			return;
+			}
+
+		if ( thefunc->Type()->Tag() != TYPE_FUNC )
+			{
+			thefunc->Error("not a function");
+			Unref(thefunc);
+			Unref(old_value);
+			return;
+			}
+
+		const Func* f = thefunc->AsFunc();
+		val_list vl { Ref() };
+		EnumVal* type;
+		switch ( tpe )
+			{
+			case element_new:
+				type = BifType::Enum::TableChange->GetVal(BifEnum::TableChange::TABLE_ELEMENT_NEW);
+			case element_changed:
+				type = BifType::Enum::TableChange->GetVal(BifEnum::TableChange::TABLE_ELEMENT_CHANGED);
+			case element_removed:
+				type = BifType::Enum::TableChange->GetVal(BifEnum::TableChange::TABLE_ELEMENT_REMOVED);
+			}
+		vl.append(type);
+
+		for ( const auto& v : *index->AsListVal()->Vals() )
+			vl.append(v->Ref());
+
+		vl.append(old_value);
+
+		f->Call(&vl);
+		Unref(thefunc);
+		}
+	catch ( InterpreterException& e )
+		{
+		}
+	}
+
 Val* TableVal::Delete(const Val* index)
 	{
 	HashKey* k = ComputeHash(index);
-	if ( k && change_func )
-		{
-		auto el = AsTable()->Lookup(k);
-		if ( el )
-			{
-			}
-		}
 	TableEntryVal* v = k ? AsNonConstTable()->RemoveEntry(k) : 0;
 	Val* va = v ? (v->Value() ? v->Value() : this->Ref()) : 0;
 
@@ -1947,6 +1992,10 @@ Val* TableVal::Delete(const Val* index)
 	delete v;
 
 	Modified();
+
+	if ( change_func )
+		CallChangeFunc(index, va->Ref(), element_removed);
+
 	return va;
 	}
 
@@ -1966,6 +2015,13 @@ Val* TableVal::Delete(const HashKey* k)
 	delete v;
 
 	Modified();
+
+	if ( change_func )
+		{
+		auto index = table_hash->RecoverVals(k);
+		CallChangeFunc(index, va->Ref(), element_removed);
+		}
+
 	return va;
 	}
 
diff --git a/src/Val.h b/src/Val.h
index 88719171b8..64c5265cab 100644
--- a/src/Val.h
+++ b/src/Val.h
@@ -879,10 +879,10 @@ public:
 	void InitTimer(double delay);
 	void DoExpire(double t);
 
-        // If the &default attribute is not a function, or the functon has
-        // already been initialized, this does nothing. Otherwise, evaluates
-        // the function in the frame allowing it to capture its closure.
-        void InitDefaultFunc(Frame* f);
+	// If the &default attribute is not a function, or the functon has
+	// already been initialized, this does nothing. Otherwise, evaluates
+	// the function in the frame allowing it to capture its closure.
+	void InitDefaultFunc(Frame* f);
 
 	unsigned int MemoryAllocation() const override;
 
@@ -922,6 +922,12 @@ protected:
 	// takes ownership of the reference.
 	double CallExpireFunc(Val *idx);
 
+	// Enum for the different kinds of changes an &on_change handler can see
+	enum OnChangeType { element_new, element_changed, element_removed };
+
+	// Calls &change_func. Takes ownership of old_value.
+	void CallChangeFunc(const Val* index, Val* old_value, OnChangeType tpe);
+
 	Val* DoClone(CloneState* state) override;
 
 	TableType* table_type;