Implement a throw or raise statement

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/StatementBuilder.kt

@@ -356,3 +356,18 @@
     log(node)
     return node
 }
+
+/**
+ * Creates a new [ThrowStatement]. The [MetadataProvider] receiver will be used to fill different
+ * meta-data using [Node.applyMetadata]. Calling this extension function outside of Kotlin requires
+ * an appropriate [MetadataProvider], such as a [LanguageFrontend] as an additional prepended
+ * argument.
+ */
+@JvmOverloads
+fun MetadataProvider.newThrowStatement(rawNode: Any? = null): ThrowStatement {
+    val node = ThrowStatement()
+    node.applyMetadata(this, EMPTY_NAME, rawNode, true)
+
+    log(node)
+    return node
+}

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/builder/Fluent.kt

@@ -1400,6 +1400,7 @@ infix fun Expression.assignAsExpr(rhs: Expression): AssignExpression {
 
     return node
 }
+
 /**
  * Creates a new [AssignExpression] with a `=` [AssignExpression.operatorCode] in the Fluent Node
  * DSL and adds it to the nearest enclosing [StatementHolder].
@@ -1414,6 +1415,23 @@ infix fun Expression.assignAsExpr(rhs: AssignExpression.() -> Unit): AssignExpre
     return node
 }
 
+/**
+ * Creates a new [ThrowStatement] in the Fluent Node DSL and adds it to the nearest enclosing
+ * [StatementHolder].
+ */
+context(LanguageFrontend<*, *>, Holder<out Node>)
+infix fun Expression.`throw`(init: (ThrowStatement.() -> Unit)?): ThrowStatement {
+    val node = (this@LanguageFrontend).newThrowStatement()
+    if (init != null) init(node)
+
+    val holder = this@Holder
+    if (holder is StatementHolder) {
+        holder += node
+    }
+
+    return node
+}
+
 /** Creates a new [Type] with the given [name] in the Fluent Node DSL. */
 fun LanguageFrontend<*, *>.t(name: CharSequence, generics: List<Type> = listOf()) =
     objectType(name, generics)

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/statements/ThrowStatement.kt

@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) 2024, Fraunhofer AISEC. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ *                    $$$$$$\  $$$$$$$\   $$$$$$\
+ *                   $$  __$$\ $$  __$$\ $$  __$$\
+ *                   $$ /  \__|$$ |  $$ |$$ /  \__|
+ *                   $$ |      $$$$$$$  |$$ |$$$$\
+ *                   $$ |      $$  ____/ $$ |\_$$ |
+ *                   $$ |  $$\ $$ |      $$ |  $$ |
+ *                   \$$$$$   |$$ |      \$$$$$   |
+ *                    \______/ \__|       \______/
+ *
+ */
+package de.fraunhofer.aisec.cpg.graph.statements
+
+import de.fraunhofer.aisec.cpg.graph.ArgumentHolder
+import de.fraunhofer.aisec.cpg.graph.edges.ast.astOptionalEdgeOf
+import de.fraunhofer.aisec.cpg.graph.edges.unwrapping
+import de.fraunhofer.aisec.cpg.graph.statements.expressions.Expression
+import java.util.Objects
+import org.apache.commons.lang3.builder.ToStringBuilder
+import org.neo4j.ogm.annotation.Relationship
+
+/** Represents a `throw` or `raise` statement. */
+class ThrowStatement : Statement(), ArgumentHolder {
+
+    /** The exception object to be raised. */
+    @Relationship(value = "EXCEPTION") var exceptionEdge = astOptionalEdgeOf<Expression>()
+    var exception by unwrapping(ThrowStatement::exceptionEdge)
+
+    /**
+     * Some languages (Python) can add a parent exception (or `cause`) to indicate that an exception
+     * was raised while handling another exception.
+     */
+    @Relationship(value = "PARENT_EXCEPTION")
+    var parentExceptionEdge = astOptionalEdgeOf<Expression>()
+    var parentException by unwrapping(ThrowStatement::parentExceptionEdge)
+
+    override fun addArgument(expression: Expression) {
+        when {
+            exception == null -> exception = expression
+            parentException == null -> parentException = expression
+        }
+    }
+
+    override fun replaceArgument(old: Expression, new: Expression): Boolean {
+        return when {
+            exception == old -> {
+                exception = new
+                true
+            }
+            parentException == old -> {
+                parentException = new
+                true
+            }
+            else -> false
+        }
+    }
+
+    override fun hasArgument(expression: Expression): Boolean {
+        return exception == expression || parentException == expression
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other !is ThrowStatement) return false
+        return super.equals(other) &&
+            exception == other.exception &&
+            parentException == other.parentException
+    }
+
+    override fun hashCode() = Objects.hash(super.hashCode(), exception, parentException)
+
+    override fun toString(): String {
+        return ToStringBuilder(this, TO_STRING_STYLE)
+            .appendSuper(super.toString())
+            .append("exception", exception)
+            .append("parentException", parentException)
+            .toString()
+    }
+}

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/passes/DFGPass.kt

@@ -130,6 +130,7 @@ class DFGPass(ctx: TranslationContext) : ComponentPass(ctx) {
             is ForStatement -> handleForStatement(node)
             is SwitchStatement -> handleSwitchStatement(node)
             is IfStatement -> handleIfStatement(node)
+            is ThrowStatement -> handleThrowStatement(node)
             // Declarations
             is FieldDeclaration -> handleFieldDeclaration(node)
             is FunctionDeclaration -> handleFunctionDeclaration(node, functionSummaries)
@@ -138,6 +139,12 @@ class DFGPass(ctx: TranslationContext) : ComponentPass(ctx) {
         }
     }
 
+    /** Handle a [ThrowStatement]. The exception and parent exception flow into the node. */
+    protected fun handleThrowStatement(node: ThrowStatement) {
+        node.exception?.let { node.prevDFGEdges += it }
+        node.parentException?.let { node.prevDFGEdges += it }
+    }
+
     protected fun handleAssignExpression(node: AssignExpression) {
         // If this is a compound assign, we also need to model a dataflow to the node itself
         if (node.isCompoundAssignment) {

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/passes/EvaluationOrderGraphPass.kt

@@ -160,6 +160,7 @@ open class EvaluationOrderGraphPass(ctx: TranslationContext) : TranslationUnitPa
         map[LookupScopeStatement::class.java] = {
             handleLookupScopeStatement(it as LookupScopeStatement)
         }
+        map[ThrowStatement::class.java] = { handleThrowStatement(it as ThrowStatement) }
     }
 
     protected fun doNothing() {
@@ -546,27 +547,38 @@ open class EvaluationOrderGraphPass(ctx: TranslationContext) : TranslationUnitPa
         // TODO(oxisto): These operator codes are highly language specific and might be more suited
         //  to be handled differently (see https://github.com/Fraunhofer-AISEC/cpg/issues/1161)
         if (node.operatorCode == "throw") {
-            handleThrowOperator(node)
+            handleThrowOperator(node, node.input)
         } else {
             handleUnspecificUnaryOperator(node)
         }
     }
 
-    protected fun handleThrowOperator(node: UnaryOperator) {
-        val input = node.input
-        createEOG(input)
-
-        val catchingScope =
-            scopeManager.firstScopeOrNull { scope -> scope is TryScope || scope is FunctionScope }
-
-        val throwType = input.type
+    /**
+     * Generates the EOG for a [node] which represents a statement/expression which throws an
+     * exception. Since some languages may accept different inputs to a throw statement (typically
+     * 1, sometimes 2, 0 is also possible), we have collect these in [inputs]. The input which is
+     * evaluated first, must be the first item in the vararg! Any `null` object in `inputs` will be
+     * filtered. We connect the throw statement internally, i.e., the inputs are evaluated from
+     * index 0 to n and then the whole node is evaluated.
+     */
+    protected fun handleThrowOperator(node: Node, vararg inputs: Expression?) {
+        inputs.filterNotNull().forEach { createEOG(it) }
         pushToEOG(node)
-        if (catchingScope is TryScope) {
-            catchingScope.catchesOrRelays[throwType] = currentPredecessors.toMutableList()
-        } else if (catchingScope is FunctionScope) {
-            catchingScope.catchesOrRelays[throwType] = currentPredecessors.toMutableList()
+
+        val input = inputs.firstOrNull()
+        val throwType = input?.type
+        if (throwType != null) {
+            val catchingScope =
+                scopeManager.firstScopeOrNull { scope ->
+                    scope is TryScope || scope is FunctionScope
+                }
+            if (catchingScope is TryScope) {
+                catchingScope.catchesOrRelays[throwType] = currentPredecessors.toMutableList()
+            } else if (catchingScope is FunctionScope) {
+                catchingScope.catchesOrRelays[throwType] = currentPredecessors.toMutableList()
+            }
         }
-        currentPredecessors.clear()
+        currentPredecessors.clear() // TODO: Should this be here or inside the if statement?
     }
 
     /**
@@ -1032,6 +1044,11 @@ open class EvaluationOrderGraphPass(ctx: TranslationContext) : TranslationUnitPa
         pushToEOG(stmt)
     }
 
+    /** This is copied & pasted with minimal adjustments from [handleThrowOperator]. */
+    protected fun handleThrowStatement(statement: ThrowStatement) {
+        handleThrowOperator(statement, statement.exception, statement.parentException)
+    }
+
     companion object {
         protected val LOGGER = LoggerFactory.getLogger(EvaluationOrderGraphPass::class.java)
 

cpg-core/src/test/kotlin/de/fraunhofer/aisec/cpg/GraphExamples.kt

@@ -1342,5 +1342,25 @@ class GraphExamples {
                     }
                 }
             }
+
+        fun prepareThrowDFGTest(
+            config: TranslationConfiguration =
+                TranslationConfiguration.builder()
+                    .defaultPasses()
+                    .registerLanguage(TestLanguage("."))
+                    .build()
+        ) =
+            testFrontend(config).build {
+                translationResult {
+                    translationUnit("some.file") {
+                        function("foo", t("void")) {
+                            body {
+                                declare { variable("a", t("short")) { literal(42) } }
+                                `throw` { call("SomeError") { ref("a") } }
+                            }
+                        }
+                    }
+                }
+            }
     }
 }

cpg-core/src/test/kotlin/de/fraunhofer/aisec/cpg/graph/ThrowStatementTest.kt

@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2022, Fraunhofer AISEC. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ *                    $$$$$$\  $$$$$$$\   $$$$$$\
+ *                   $$  __$$\ $$  __$$\ $$  __$$\
+ *                   $$ /  \__|$$ |  $$ |$$ /  \__|
+ *                   $$ |      $$$$$$$  |$$ |$$$$\
+ *                   $$ |      $$  ____/ $$ |\_$$ |
+ *                   $$ |  $$\ $$ |      $$ |  $$ |
+ *                   \$$$$$   |$$ |      \$$$$$   |
+ *                    \______/ \__|       \______/
+ *
+ */
+package de.fraunhofer.aisec.cpg.graph
+
+import de.fraunhofer.aisec.cpg.GraphExamples.Companion.testFrontend
+import de.fraunhofer.aisec.cpg.TranslationConfiguration
+import de.fraunhofer.aisec.cpg.frontends.TestLanguage
+import de.fraunhofer.aisec.cpg.graph.builder.*
+import de.fraunhofer.aisec.cpg.graph.statements.ThrowStatement
+import de.fraunhofer.aisec.cpg.graph.statements.expressions.Block
+import de.fraunhofer.aisec.cpg.graph.statements.expressions.CallExpression
+import de.fraunhofer.aisec.cpg.test.assertLocalName
+import kotlin.test.*
+
+class ThrowStatementTest {
+    @Test
+    fun testThrow() {
+        val result =
+            testFrontend(
+                    TranslationConfiguration.builder()
+                        .defaultPasses()
+                        .registerLanguage(TestLanguage("."))
+                        .build()
+                )
+                .build {
+                    translationResult {
+                        translationUnit("some.file") {
+                            function("foo", t("void")) {
+                                body {
+                                    `throw` {}
+                                    `throw` { call("SomeError") }
+                                    `throw` {
+                                        call("SomeError")
+                                        call("SomeError2")
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+
+        // Let's assert that we did this correctly
+        val main = result.functions["foo"]
+        assertNotNull(main)
+        val body = main.body
+        assertIs<Block>(body)
+
+        val emptyThrow = body.statements.getOrNull(0)
+        assertIs<ThrowStatement>(emptyThrow)
+        println(emptyThrow.toString()) // This is only here to simulate a higher test coverage
+        assertNull(emptyThrow.exception)
+        assertTrue(emptyThrow.prevDFG.isEmpty())
+
+        val throwWithExc = body.statements.getOrNull(1)
+        assertIs<ThrowStatement>(throwWithExc)
+        println(throwWithExc.toString()) // This is only here to simulate a higher test coverage
+        val throwCall = throwWithExc.exception
+        assertIs<CallExpression>(throwCall)
+        assertLocalName("SomeError", throwCall)
+        assertEquals(setOf<Node>(throwCall), throwWithExc.prevDFG.toSet())
+
+        val throwWithExcAndParent = body.statements.getOrNull(2)
+        assertIs<ThrowStatement>(throwWithExcAndParent)
+        println(
+            throwWithExcAndParent.toString()
+        ) // This is only here to simulate a higher test coverage
+        val throwCallException = throwWithExcAndParent.exception
+        assertIs<CallExpression>(throwCallException)
+        assertLocalName("SomeError", throwCallException)
+        val throwCallParent = throwWithExcAndParent.parentException
+        assertIs<CallExpression>(throwCallParent)
+        assertLocalName("SomeError2", throwCallParent)
+        assertEquals(
+            setOf<Node>(throwCallException, throwCallParent),
+            throwWithExcAndParent.prevDFG.toSet()
+        )
+    }
+}