From 12f54b55a2e92c81a15468315dc2eadde4f6c472 Mon Sep 17 00:00:00 2001
From: Bhargava Shastry <bhargava.shastry@ethereum.org>
Date: Mon, 29 Jul 2019 16:38:24 +0200
Subject: [PATCH] Pseudo randomly add checks

---
 test/tools/ossfuzz/protoToAbiV2.cpp | 53 +++++++++++++++++------------
 test/tools/ossfuzz/protoToAbiV2.h   | 13 +++++--
 2 files changed, 41 insertions(+), 25 deletions(-)

diff --git a/test/tools/ossfuzz/protoToAbiV2.cpp b/test/tools/ossfuzz/protoToAbiV2.cpp
index 84c4ab0be..daea61c9a 100644
--- a/test/tools/ossfuzz/protoToAbiV2.cpp
+++ b/test/tools/ossfuzz/protoToAbiV2.cpp
@@ -353,20 +353,20 @@ void ProtoConverter::visit(ValueType const& _x)
 {
 	switch (_x.value_type_oneof_case())
 	{
-		case ValueType::kInty:
-			visit(_x.inty());
-			break;
-		case ValueType::kByty:
-			visit(_x.byty());
-			break;
-		case ValueType::kAdty:
-			visit(_x.adty());
-			break;
-		case ValueType::kBoolty:
-			visit(_x.boolty());
-			break;
-		case ValueType::VALUE_TYPE_ONEOF_NOT_SET:
-			break;
+	case ValueType::kInty:
+		visit(_x.inty());
+		break;
+	case ValueType::kByty:
+		visit(_x.byty());
+		break;
+	case ValueType::kAdty:
+		visit(_x.adty());
+		break;
+	case ValueType::kBoolty:
+		visit(_x.boolty());
+		break;
+	case ValueType::VALUE_TYPE_ONEOF_NOT_SET:
+		break;
 	}
 }
 
@@ -500,8 +500,10 @@ unsigned ProtoConverter::resizeDimension(
 		addVarDef(lhs, rhs);
 	}
 
-	// if (c.length != l)
-	checkResizeOp(_param, length);
+	// Add checks on array length pseudo randomly
+	if (addCheck(getNextCounter()))
+		// if (c.length != l)
+		checkResizeOp(_param, length);
 	return length;
 }
 
@@ -517,12 +519,19 @@ void ProtoConverter::resizeHelper(
 	// (depth-first) recurse otherwise.
 	if (_arrInfoVec.empty())
 	{
-		// expression name is _var
-		// value is a value of base type
-		std::string value = getValueByBaseType(_x);
-		// add assignment and check
-		DataType dataType = getDataTypeByBaseType(_x);
-		addCheckedVarDef(dataType, _varName, _paramName, value);
+		// We are at the leaf node now.
+		// To ensure we do not create a very large test case
+		// especially for multidimensional dynamic arrays,
+		// we create a checked assignment pseudo randomly.
+		if (addCheck(getNextCounter()))
+		{
+			// expression name is _var
+			// value is a value of base type
+			std::string value = getValueByBaseType(_x);
+			// add assignment and check
+			DataType dataType = getDataTypeByBaseType(_x);
+			addCheckedVarDef(dataType, _varName, _paramName, value);
+		}
 	}
 	else
 	{
diff --git a/test/tools/ossfuzz/protoToAbiV2.h b/test/tools/ossfuzz/protoToAbiV2.h
index 5dde8b697..50ca4dc9c 100644
--- a/test/tools/ossfuzz/protoToAbiV2.h
+++ b/test/tools/ossfuzz/protoToAbiV2.h
@@ -310,7 +310,7 @@ private:
 
 	static unsigned getIntWidth(IntegerType const& _x)
 	{
-		return 8 * ((_x.width() % 32) + 1);
+		return 8 * (_x.width() % 32 + 1);
 	}
 
 	static bool isIntSigned(IntegerType const& _x)
@@ -325,12 +325,12 @@ private:
 
 	static std::string getIntTypeAsString(IntegerType const& _x)
 	{
-		return ((isIntSigned(_x) ? "int" : "uint") + std::to_string(getIntWidth(_x)));
+		return (isIntSigned(_x) ? "int" : "uint") + std::to_string(getIntWidth(_x));
 	}
 
 	static unsigned getFixedByteWidth(FixedByteType const& _x)
 	{
-		return (_x.width() % 32) + 1;
+		return _x.width() % 32 + 1;
 	}
 
 	static std::string getFixedByteTypeAsString(FixedByteType const& _x)
@@ -413,6 +413,10 @@ private:
 			_counter,
 			_isHexLiteral
 		);
+
+	static bool addCheck(unsigned _counter)
+	{
+		return _counter % s_arrayCheckFrequency == 0;
 	}
 
 	/// Contains the test program
@@ -434,6 +438,9 @@ private:
 	static unsigned constexpr s_maxArrayLength = 4;
 	static unsigned constexpr s_maxArrayDimensions = 4;
 	static unsigned constexpr s_maxDynArrayLength = 256;
+	/// Add check only if counter returned by getNextCounter()
+	/// is divisible by s_arrayCheckFrequency
+	static unsigned constexpr s_arrayCheckFrequency = 11;
 	/// Prefixes for declared and parameterized variable names
 	static auto constexpr s_varNamePrefix = "x_";
 	static auto constexpr s_paramNamePrefix = "c_";