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Extracted call/cast replacement into separate pass (#1499)
* Extracted call/cast replacement into separate pass Multiple languages, such as Go and C++ support "functional style casts", in the form of int(5). During the frontend parsing, they are indistinguishable from function calls. Therefore, we need to do a cleanup after all types are known but before other passes are invoked that replace those calls with casts. The proposed solution is to include a new language trait HasFuntionalCasts and to move the logic from the GoExtraPass into a separate, language-neutral one. Fixes #1487 * Added annotation to pass that requires a language trait
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154 changes: 154 additions & 0 deletions
154
cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/passes/ReplaceCallCastPass.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,154 @@ | ||
| /* | ||
| * 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.passes | ||
|
|
||
| import de.fraunhofer.aisec.cpg.TranslationContext | ||
| import de.fraunhofer.aisec.cpg.frontends.Handler | ||
| import de.fraunhofer.aisec.cpg.frontends.HasFunctionalCasts | ||
| import de.fraunhofer.aisec.cpg.frontends.Language | ||
| import de.fraunhofer.aisec.cpg.frontends.LanguageFrontend | ||
| import de.fraunhofer.aisec.cpg.graph.* | ||
| import de.fraunhofer.aisec.cpg.graph.declarations.TranslationUnitDeclaration | ||
| import de.fraunhofer.aisec.cpg.graph.statements.expressions.CallExpression | ||
| import de.fraunhofer.aisec.cpg.graph.statements.expressions.CastExpression | ||
| import de.fraunhofer.aisec.cpg.graph.statements.expressions.ConstructExpression | ||
| import de.fraunhofer.aisec.cpg.graph.statements.expressions.UnaryOperator | ||
| import de.fraunhofer.aisec.cpg.graph.types.Type | ||
| import de.fraunhofer.aisec.cpg.helpers.SubgraphWalker | ||
| import de.fraunhofer.aisec.cpg.passes.order.DependsOn | ||
| import de.fraunhofer.aisec.cpg.passes.order.ExecuteBefore | ||
| import de.fraunhofer.aisec.cpg.passes.order.RequiresLanguageTrait | ||
|
|
||
| /** | ||
| * If a [Language] has the trait [HasFunctionalCasts], we cannot distinguish between a | ||
| * [CallExpression] and a [CastExpression] during the initial translation. This stems from the fact | ||
| * that we might not know all the types yet. We therefore need to handle them as regular call | ||
| * expression in a [LanguageFrontend] or [Handler] and then later replace them with a | ||
| * [CastExpression], if the [CallExpression.callee] refers to name of a [Type] rather than a | ||
| * function. | ||
| */ | ||
| @ExecuteBefore(EvaluationOrderGraphPass::class) | ||
| @DependsOn(TypeResolver::class) | ||
| @RequiresLanguageTrait(HasFunctionalCasts::class) | ||
| class ReplaceCallCastPass(ctx: TranslationContext) : TranslationUnitPass(ctx) { | ||
| private lateinit var walker: SubgraphWalker.ScopedWalker | ||
|
|
||
| override fun accept(tu: TranslationUnitDeclaration) { | ||
| walker = SubgraphWalker.ScopedWalker(ctx.scopeManager) | ||
| walker.registerHandler { _, parent, node -> | ||
| when (node) { | ||
| is CallExpression -> handleCall(node, parent) | ||
| } | ||
| } | ||
|
|
||
| walker.iterate(tu) | ||
| } | ||
|
|
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| private fun handleCall(call: CallExpression, parent: Node?) { | ||
| // Make sure, we are not accidentally handling construct expressions (since they also derive | ||
| // from call expressions) | ||
| if (call is ConstructExpression) { | ||
| return | ||
| } | ||
|
|
||
| // We need to check, whether the "callee" refers to a type and if yes, convert it into a | ||
| // cast expression. And this is only really necessary, if the function call has a single | ||
| // argument. | ||
| var callee = call.callee | ||
| if (parent != null && callee != null && call.arguments.size == 1) { | ||
| val language = parent.language | ||
|
|
||
| var pointer = false | ||
| // If the argument is a UnaryOperator, unwrap them | ||
| if (callee is UnaryOperator && callee.operatorCode == "*") { | ||
| pointer = true | ||
| callee = callee.input | ||
| } | ||
|
|
||
| // First, check if this is a built-in type | ||
| if (language?.builtInTypes?.contains(callee.name.toString()) == true) { | ||
| walker.replaceCallWithCast(callee.name.toString(), parent, call, false) | ||
| } else { | ||
| // If not, then this could still refer to an existing type. We need to make sure | ||
| // that we take the current namespace into account | ||
| val fqn = | ||
| if (callee.name.parent == null) { | ||
| scopeManager.currentNamespace.fqn(callee.name.localName) | ||
| } else { | ||
| callee.name | ||
| } | ||
|
|
||
| if (typeManager.typeExists(fqn.toString())) { | ||
| walker.replaceCallWithCast(fqn, parent, call, pointer) | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| override fun cleanup() { | ||
| // Nothing to do | ||
| } | ||
| } | ||
|
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||
| context(ContextProvider) | ||
| fun SubgraphWalker.ScopedWalker.replaceCallWithCast( | ||
| typeName: CharSequence, | ||
| parent: Node, | ||
| call: CallExpression, | ||
| pointer: Boolean, | ||
| ) { | ||
| val cast = newCastExpression() | ||
| cast.code = call.code | ||
| cast.language = call.language | ||
| cast.location = call.location | ||
| cast.castType = | ||
| if (pointer) { | ||
| call.objectType(typeName).pointer() | ||
| } else { | ||
| call.objectType(typeName) | ||
| } | ||
| cast.expression = call.arguments.single() | ||
| cast.name = cast.castType.name | ||
|
|
||
| if (parent !is ArgumentHolder) { | ||
| Pass.log.error( | ||
| "Parent AST node of call expression is not an argument holder. Cannot convert to cast expression. Further analysis might not be entirely accurate." | ||
| ) | ||
| return | ||
| } | ||
|
|
||
| val success = parent.replaceArgument(call, cast) | ||
| if (!success) { | ||
| Pass.log.error( | ||
| "Replacing call expression with cast expression was not successful. Further analysis might not be entirely accurate." | ||
| ) | ||
| } else { | ||
| call.disconnectFromGraph() | ||
|
|
||
| // Make sure to inform the walker about our change | ||
| this.registerReplacement(call, cast) | ||
| } | ||
| } |
38 changes: 38 additions & 0 deletions
38
cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/passes/order/RequiresLanguageTrait.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,38 @@ | ||
| /* | ||
| * 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.passes.order | ||
|
|
||
| import de.fraunhofer.aisec.cpg.frontends.Language | ||
| import de.fraunhofer.aisec.cpg.frontends.LanguageTrait | ||
| import kotlin.reflect.KClass | ||
|
|
||
| /** | ||
| * This annotation can only enable a pass if its target language implements a given [LanguageTrait]. | ||
| * | ||
| * This annotation is [Repeatable]. In this case, all specified language traits must exist on the | ||
| * [Language]. | ||
| */ | ||
| @Repeatable annotation class RequiresLanguageTrait(val value: KClass<out LanguageTrait>) |
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