From 68b7f401845ffdf838db7672823e2645af43b9a6 Mon Sep 17 00:00:00 2001
From: Bhargava Shastry <bhargava.shastry@ethereum.org>
Date: Wed, 17 Apr 2019 11:41:28 +0200
Subject: [PATCH] ossfuzz: Fixes buggy generation of duplicate case literals

---
 test/tools/ossfuzz/protoToYul.cpp | 55 ++++++++++++++++++++++++++++---
 test/tools/ossfuzz/protoToYul.h   |  5 +++
 2 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/test/tools/ossfuzz/protoToYul.cpp b/test/tools/ossfuzz/protoToYul.cpp
index a998e3255..5e99d024d 100644
--- a/test/tools/ossfuzz/protoToYul.cpp
+++ b/test/tools/ossfuzz/protoToYul.cpp
@@ -31,7 +31,7 @@ string ProtoConverter::createHex(string const& _hexBytes) const
 		});
 		tmp = tmp.substr(0, 64);
 	}
-	// We need this awkward if case hex literals cannot be empty.
+	// We need this awkward if case because hex literals cannot be empty.
 	if (tmp.empty())
 		tmp = "1";
 	return tmp;
@@ -50,6 +50,41 @@ string ProtoConverter::createAlphaNum(string const& _strBytes) const
 	return tmp;
 }
 
+bool ProtoConverter::isCaseLiteralUnique(Literal const& _x)
+{
+	std::string tmp;
+	bool isUnique = false;
+	bool isEmptyString = false;
+	switch (_x.literal_oneof_case())
+	{
+		case Literal::kIntval:
+			tmp = std::to_string(_x.intval());
+			break;
+		case Literal::kHexval:
+			tmp = "0x" + createHex(_x.hexval());
+			break;
+		case Literal::kStrval:
+			tmp = createAlphaNum(_x.strval());
+			if (tmp.empty())
+			{
+				isEmptyString = true;
+				tmp = std::to_string(0);
+			}
+			else
+				tmp = "\"" + tmp + "\"";
+			break;
+		case Literal::LITERAL_ONEOF_NOT_SET:
+			tmp = std::to_string(1);
+			break;
+	}
+	if (!_x.has_strval() || isEmptyString)
+		isUnique = m_switchLiteralSetPerScope.top().insert(dev::u256(tmp)).second;
+	else
+		isUnique = m_switchLiteralSetPerScope.top().insert(
+				dev::u256(dev::h256(tmp, dev::h256::FromBinary, dev::h256::AlignLeft))).second;
+	return isUnique;
+}
+
 void ProtoConverter::visit(Literal const& _x)
 {
 	switch (_x.literal_oneof_case())
@@ -319,21 +354,31 @@ void ProtoConverter::visit(ForStmt const& _x)
 
 void ProtoConverter::visit(CaseStmt const& _x)
 {
-	m_output << "case ";
-	visit(_x.case_lit());
-	m_output << " ";
-	visit(_x.case_block());
+	// Silently ignore duplicate case literals
+	if (isCaseLiteralUnique(_x.case_lit()))
+	{
+		m_output << "case ";
+		visit(_x.case_lit());
+		m_output << " ";
+		visit(_x.case_block());
+	}
 }
 
 void ProtoConverter::visit(SwitchStmt const& _x)
 {
 	if (_x.case_stmt_size() > 0 || _x.has_default_block())
 	{
+		std::set<dev::u256> s;
+		m_switchLiteralSetPerScope.push(s);
 		m_output << "switch ";
 		visit(_x.switch_expr());
 		m_output << "\n";
+
 		for (auto const& caseStmt: _x.case_stmt())
 			visit(caseStmt);
+
+		m_switchLiteralSetPerScope.pop();
+
 		if (_x.has_default_block())
 		{
 			m_output << "default ";
diff --git a/test/tools/ossfuzz/protoToYul.h b/test/tools/ossfuzz/protoToYul.h
index b38bcda91..6c78dbcaa 100644
--- a/test/tools/ossfuzz/protoToYul.h
+++ b/test/tools/ossfuzz/protoToYul.h
@@ -21,8 +21,11 @@
 #include <ostream>
 #include <sstream>
 #include <stack>
+#include <set>
 
 #include <test/tools/ossfuzz/yulProto.pb.h>
+#include <libdevcore/Common.h>
+#include <libdevcore/FixedHash.h>
 
 namespace yul
 {
@@ -68,12 +71,14 @@ private:
 
 	std::string createHex(std::string const& _hexBytes) const;
 	std::string createAlphaNum(std::string const& _strBytes) const;
+	bool isCaseLiteralUnique(Literal const&);
 
 	std::ostringstream m_output;
 	std::stack<uint8_t> m_numVarsPerScope;
 	int32_t m_numLiveVars;
 	int32_t m_numNestedForLoops;
 	std::stack<bool> m_inForScope;
+	std::stack<std::set<dev::u256>> m_switchLiteralSetPerScope;
 };
 }
 }