1 //=== CXXSelfAssignmentChecker.cpp -----------------------------*- 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 CXXSelfAssignmentChecker, which tests all custom defined
10 // copy and move assignment operators for the case of self assignment, thus
11 // where the parameter refers to the same location where the this pointer
12 // points to. The checker itself does not do any checks at all, but it
13 // causes the analyzer to check every copy and move assignment operator twice:
14 // once for when 'this' aliases with the parameter and once for when it may not.
15 // It is the task of the other enabled checkers to find the bugs in these two
16 // different cases.
17 //
18 //===----------------------------------------------------------------------===//
19
20 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
21 #include "clang/StaticAnalyzer/Core/Checker.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
23
24 using namespace clang;
25 using namespace ento;
26
27 namespace {
28
29 class CXXSelfAssignmentChecker : public Checker<check::BeginFunction> {
30 public:
31 CXXSelfAssignmentChecker();
32 void checkBeginFunction(CheckerContext &C) const;
33 };
34 }
35
CXXSelfAssignmentChecker()36 CXXSelfAssignmentChecker::CXXSelfAssignmentChecker() {}
37
checkBeginFunction(CheckerContext & C) const38 void CXXSelfAssignmentChecker::checkBeginFunction(CheckerContext &C) const {
39 if (!C.inTopFrame())
40 return;
41 const auto *LCtx = C.getLocationContext();
42 const auto *MD = dyn_cast<CXXMethodDecl>(LCtx->getDecl());
43 if (!MD)
44 return;
45 if (!MD->isCopyAssignmentOperator() && !MD->isMoveAssignmentOperator())
46 return;
47 auto &State = C.getState();
48 auto &SVB = C.getSValBuilder();
49 auto ThisVal =
50 State->getSVal(SVB.getCXXThis(MD, LCtx->getStackFrame()));
51 auto Param = SVB.makeLoc(State->getRegion(MD->getParamDecl(0), LCtx));
52 auto ParamVal = State->getSVal(Param);
53
54 ProgramStateRef SelfAssignState = State->bindLoc(Param, ThisVal, LCtx);
55 const NoteTag *SelfAssignTag =
56 C.getNoteTag([MD](PathSensitiveBugReport &BR) -> std::string {
57 SmallString<256> Msg;
58 llvm::raw_svector_ostream Out(Msg);
59 Out << "Assuming " << MD->getParamDecl(0)->getName() << " == *this";
60 return std::string(Out.str());
61 });
62 C.addTransition(SelfAssignState, SelfAssignTag);
63
64 ProgramStateRef NonSelfAssignState = State->bindLoc(Param, ParamVal, LCtx);
65 const NoteTag *NonSelfAssignTag =
66 C.getNoteTag([MD](PathSensitiveBugReport &BR) -> std::string {
67 SmallString<256> Msg;
68 llvm::raw_svector_ostream Out(Msg);
69 Out << "Assuming " << MD->getParamDecl(0)->getName() << " != *this";
70 return std::string(Out.str());
71 });
72 C.addTransition(NonSelfAssignState, NonSelfAssignTag);
73 }
74
registerCXXSelfAssignmentChecker(CheckerManager & Mgr)75 void ento::registerCXXSelfAssignmentChecker(CheckerManager &Mgr) {
76 Mgr.registerChecker<CXXSelfAssignmentChecker>();
77 }
78
shouldRegisterCXXSelfAssignmentChecker(const CheckerManager & mgr)79 bool ento::shouldRegisterCXXSelfAssignmentChecker(const CheckerManager &mgr) {
80 return true;
81 }
82