1 // SmartPtrModeling.cpp - Model behavior of C++ smart pointers - C++ ------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file defines a checker that models various aspects of 10 // C++ smart pointer behavior. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "Move.h" 15 16 #include "clang/AST/ExprCXX.h" 17 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" 18 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 19 #include "clang/StaticAnalyzer/Core/Checker.h" 20 #include "clang/StaticAnalyzer/Core/CheckerManager.h" 21 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" 22 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 23 24 using namespace clang; 25 using namespace ento; 26 27 namespace { 28 class SmartPtrModeling : public Checker<eval::Call> { 29 bool isNullAfterMoveMethod(const CallEvent &Call) const; 30 31 public: 32 bool evalCall(const CallEvent &Call, CheckerContext &C) const; 33 }; 34 } // end of anonymous namespace 35 36 bool SmartPtrModeling::isNullAfterMoveMethod(const CallEvent &Call) const { 37 // TODO: Update CallDescription to support anonymous calls? 38 // TODO: Handle other methods, such as .get() or .release(). 39 // But once we do, we'd need a visitor to explain null dereferences 40 // that are found via such modeling. 41 const auto *CD = dyn_cast_or_null<CXXConversionDecl>(Call.getDecl()); 42 return CD && CD->getConversionType()->isBooleanType(); 43 } 44 45 bool SmartPtrModeling::evalCall(const CallEvent &Call, 46 CheckerContext &C) const { 47 if (!isNullAfterMoveMethod(Call)) 48 return false; 49 50 ProgramStateRef State = C.getState(); 51 const MemRegion *ThisR = 52 cast<CXXInstanceCall>(&Call)->getCXXThisVal().getAsRegion(); 53 54 if (!move::isMovedFrom(State, ThisR)) { 55 // TODO: Model this case as well. At least, avoid invalidation of globals. 56 return false; 57 } 58 59 // TODO: Add a note to bug reports describing this decision. 60 C.addTransition( 61 State->BindExpr(Call.getOriginExpr(), C.getLocationContext(), 62 C.getSValBuilder().makeZeroVal(Call.getResultType()))); 63 return true; 64 } 65 66 void ento::registerSmartPtrModeling(CheckerManager &Mgr) { 67 Mgr.registerChecker<SmartPtrModeling>(); 68 } 69 70 bool ento::shouldRegisterSmartPtrModeling(const LangOptions &LO) { 71 return LO.CPlusPlus; 72 } 73