Take operator into account when evaluating conditional expressions

cpg-analysis/src/main/kotlin/de/fraunhofer/aisec/cpg/analysis/ValueEvaluator.kt

@@ -179,6 +179,7 @@ open class ValueEvaluator(
             "<" -> handleLess(lhsValue, rhsValue, expr)
             "<=" -> handleLEq(lhsValue, rhsValue, expr)
             "==" -> handleEq(lhsValue, rhsValue, expr)
+            "!=" -> handleNEq(lhsValue, rhsValue, expr)
             else -> cannotEvaluate(expr as Node, this)
         }
     }
@@ -298,6 +299,14 @@ open class ValueEvaluator(
         }
     }
 
+    private fun handleNEq(lhsValue: Any?, rhsValue: Any?, expr: Expression?): Any? {
+        return if (lhsValue is Number && rhsValue is Number) {
+            lhsValue.compareTo(rhsValue) != 0
+        } else {
+            cannotEvaluate(expr, this)
+        }
+    }
+
     /**
      * We handle some basic unary operators. These also affect pointers and dereferences for
      * languages that support them.
@@ -361,12 +370,17 @@ open class ValueEvaluator(
     }
 
     protected open fun handleConditionalExpression(expr: ConditionalExpression, depth: Int): Any? {
+        var condition = expr.condition
+
         // Assume that condition is a binary operator
-        if (expr.condition is BinaryOperator) {
-            val lhs = evaluateInternal((expr.condition as? BinaryOperator)?.lhs, depth)
-            val rhs = evaluateInternal((expr.condition as? BinaryOperator)?.rhs, depth)
+        if (condition is BinaryOperator) {
+            val lhs = evaluateInternal(condition.lhs, depth)
+            val rhs = evaluateInternal(condition.rhs, depth)
+
+            // Compute the effect of the comparison
+            val comparison = computeBinaryOpEffect(lhs, rhs, condition)
 
-            return if (lhs == rhs) {
+            return if (comparison == true) {
                 evaluateInternal(expr.thenExpression, depth + 1)
             } else {
                 evaluateInternal(expr.elseExpression, depth + 1)

cpg-analysis/src/test/kotlin/de/fraunhofer/aisec/cpg/analysis/ValueEvaluatorTest.kt

@@ -177,7 +177,7 @@ class ValueEvaluatorTest {
         val main = mainClass.functions["main"]
         assertNotNull(main)
 
-        val s = main.refs("s").last()
+        val s = main.refs("s").lastOrNull()
         assertNotNull(s)
 
         var value = s.evaluate()
@@ -186,7 +186,7 @@ class ValueEvaluatorTest {
         value = s.evaluate(MultiValueEvaluator())
         assertEquals(setOf("big!?", "small!?"), value)
 
-        val i = main.refs("i").last()
+        val i = main.refs("i").lastOrNull()
         assertNotNull(i)
 
         value = i.evaluate()
@@ -741,15 +741,15 @@ class ValueEvaluatorTest {
 
     @Test
     fun testHandleUnary() {
-        with(TestHandler(TestLanguageFrontend())) {
-            val neg = newUnaryOperator("-", false, true)
+        with(TestLanguageFrontend()) {
+            val neg = newUnaryOperator("-", postfix = false, prefix = true)
             neg.input = newLiteral(3, primitiveType("int"))
             assertEquals(-3, ValueEvaluator().evaluate(neg))
 
             neg.input = newLiteral(3.5, primitiveType("double"))
             assertEquals(-3.5, ValueEvaluator().evaluate(neg))
 
-            val plusplus = newUnaryOperator("++", true, false)
+            val plusplus = newUnaryOperator("++", postfix = true, prefix = false)
             plusplus.input = newLiteral(3, primitiveType("int"))
             assertEquals(4, ValueEvaluator().evaluate(plusplus))
 
@@ -759,7 +759,7 @@ class ValueEvaluatorTest {
             plusplus.input = newLiteral(3.5f, primitiveType("float"))
             assertEquals(4.5f, ValueEvaluator().evaluate(plusplus))
 
-            val minusminus = newUnaryOperator("--", true, false)
+            val minusminus = newUnaryOperator("--", postfix = true, prefix = false)
             minusminus.input = newLiteral(3, primitiveType("int"))
             assertEquals(2, ValueEvaluator().evaluate(minusminus))
 
@@ -770,4 +770,23 @@ class ValueEvaluatorTest {
             assertEquals(2.5f, ValueEvaluator().evaluate(minusminus))
         }
     }
+
+    @Test
+    fun handleConditionalExpression() {
+        with(TestLanguageFrontend()) {
+            val a = newVariableDeclaration("a")
+            a.initializer = newLiteral(1)
+
+            val aRef = newReference("a")
+            aRef.refersTo = a
+            aRef.prevDFG = mutableSetOf(a)
+
+            val comparison = newBinaryOperator("!=")
+            comparison.lhs = aRef
+            comparison.rhs = newLiteral(1)
+
+            val cond = newConditionalExpression(comparison, newLiteral(2), aRef)
+            assertEquals(1, cond.evaluate())
+        }
+    }
 }