From 3521a92a004020170dd79c79a7ad99d58eb9bd8a Mon Sep 17 00:00:00 2001
From: Jon Siwek <jsiwek@illinois.edu>
Date: Fri, 22 Aug 2014 16:49:10 -0500
Subject: [PATCH] Detect functions that try to bind variables from an outer
 scope.

And raise an error saying that's not supported.
Addresses BIT-1233.
---
 src/Stmt.cc                                   |  9 ++++-
 src/Var.cc                                    | 39 +++++++++++++++++++
 .../Baseline/language.outer_param_binding/out |  3 ++
 .../btest/language/outer_param_binding.bro    | 27 +++++++++++++
 4 files changed, 76 insertions(+), 2 deletions(-)
 create mode 100644 testing/btest/Baseline/language.outer_param_binding/out
 create mode 100644 testing/btest/language/outer_param_binding.bro

diff --git a/src/Stmt.cc b/src/Stmt.cc
index 3571cad197..cb716b3f15 100644
--- a/src/Stmt.cc
+++ b/src/Stmt.cc
@@ -660,8 +660,13 @@ void Case::Describe(ODesc* d) const
 
 TraversalCode Case::Traverse(TraversalCallback* cb) const
 	{
-	TraversalCode tc = cases->Traverse(cb);
-	HANDLE_TC_STMT_PRE(tc);
+	TraversalCode tc;
+
+	if ( cases )
+		{
+		tc = cases->Traverse(cb);
+		HANDLE_TC_STMT_PRE(tc);
+		}
 
 	tc = s->Traverse(cb);
 	HANDLE_TC_STMT_PRE(tc);
diff --git a/src/Var.cc b/src/Var.cc
index aa45faaf41..6cb113a11e 100644
--- a/src/Var.cc
+++ b/src/Var.cc
@@ -9,6 +9,7 @@
 #include "Serializer.h"
 #include "RemoteSerializer.h"
 #include "EventRegistry.h"
+#include "Traverse.h"
 
 static Val* init_val(Expr* init, const BroType* t, Val* aggr)
 	{
@@ -392,6 +393,34 @@ void begin_func(ID* id, const char* module_name, function_flavor flavor,
 		}
 	}
 
+class OuterParamBindingFinder : public TraversalCallback {
+public:
+	OuterParamBindingFinder(Scope* s)
+		: scope(s) { }
+
+	virtual TraversalCode PreExpr(const Expr*);
+
+	Scope* scope;
+	vector<const NameExpr*> outer_param_references;
+};
+
+TraversalCode OuterParamBindingFinder::PreExpr(const Expr* expr)
+	{
+	if ( expr->Tag() != EXPR_NAME )
+		return TC_CONTINUE;
+
+	const NameExpr* e = static_cast<const NameExpr*>(expr);
+
+	if ( e->Id()->IsGlobal() )
+		return TC_CONTINUE;
+
+	if ( scope->GetIDs()->Lookup(e->Id()->Name()) )
+		return TC_CONTINUE;
+
+	outer_param_references.push_back(e);
+	return TC_CONTINUE;
+	}
+
 void end_func(Stmt* body, attr_list* attrs)
 	{
 	int frame_size = current_scope()->Length();
@@ -429,6 +458,16 @@ void end_func(Stmt* body, attr_list* attrs)
 			}
 		}
 
+	if ( streq(id->Name(), "anonymous-function") )
+		{
+		OuterParamBindingFinder cb(scope);
+		body->Traverse(&cb);
+
+		for ( size_t i = 0; i < cb.outer_param_references.size(); ++i )
+			cb.outer_param_references[i]->Error(
+						"referencing outer function parameters not supported");
+		}
+
 	if ( id->HasVal() )
 		id->ID_Val()->AsFunc()->AddBody(body, inits, frame_size, priority);
 	else
diff --git a/testing/btest/Baseline/language.outer_param_binding/out b/testing/btest/Baseline/language.outer_param_binding/out
new file mode 100644
index 0000000000..3dfc82da3e
--- /dev/null
+++ b/testing/btest/Baseline/language.outer_param_binding/out
@@ -0,0 +1,3 @@
+error in /Users/jsiwek/Projects/bro/bro/testing/btest/.tmp/language.outer_param_binding/outer_param_binding.bro, line 16: referencing outer function parameters not supported (c)
+error in /Users/jsiwek/Projects/bro/bro/testing/btest/.tmp/language.outer_param_binding/outer_param_binding.bro, line 16: referencing outer function parameters not supported (d)
+error in /Users/jsiwek/Projects/bro/bro/testing/btest/.tmp/language.outer_param_binding/outer_param_binding.bro, line 17: referencing outer function parameters not supported (b)
diff --git a/testing/btest/language/outer_param_binding.bro b/testing/btest/language/outer_param_binding.bro
new file mode 100644
index 0000000000..fb37fd4712
--- /dev/null
+++ b/testing/btest/language/outer_param_binding.bro
@@ -0,0 +1,27 @@
+# @TEST-EXEC-FAIL: bro -b %INPUT >out 2>&1
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff out
+
+type Foo: record {
+	x: function(a: string) : string;
+};
+
+function bar(b: string, c: string)
+	{
+	local f: Foo;
+	local d = 8;
+	f = [$x=function(a: string) : string
+			{
+			local x = 0;
+			print x;
+			print c, d;
+			return cat(a, " ", b);
+			}
+		];
+
+	print f$x("2");
+	}
+
+event bro_init()
+	{
+	bar("1", "20");
+	}