1 //===- CastValueChecker - Model implementation of custom RTTIs --*- C++ -*-===//
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
7 //===----------------------------------------------------------------------===//
9 // This defines CastValueChecker which models casts of custom RTTIs.
11 //===----------------------------------------------------------------------===//
13 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
14 #include "clang/StaticAnalyzer/Core/Checker.h"
15 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
16 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
18 #include "llvm/ADT/Optional.h"
20 using namespace clang;
24 class CastValueChecker : public Checker<eval::Call> {
26 std::function<void(const CastValueChecker *, const CallExpr *,
27 DefinedOrUnknownSVal, CheckerContext &)>;
30 // We have three cases to evaluate a cast:
31 // 1) The parameter is non-null, the return value is non-null
32 // 2) The parameter is non-null, the return value is null
33 // 3) The parameter is null, the return value is null
35 // cast: 1; dyn_cast: 1, 2; cast_or_null: 1, 3; dyn_cast_or_null: 1, 2, 3.
36 bool evalCall(const CallEvent &Call, CheckerContext &C) const;
39 // These are known in the LLVM project.
40 const CallDescriptionMap<CastCheck> CDM = {
41 {{{"llvm", "cast"}, 1}, &CastValueChecker::evalCast},
42 {{{"llvm", "dyn_cast"}, 1}, &CastValueChecker::evalDynCast},
43 {{{"llvm", "cast_or_null"}, 1}, &CastValueChecker::evalCastOrNull},
44 {{{"llvm", "dyn_cast_or_null"}, 1},
45 &CastValueChecker::evalDynCastOrNull}};
47 void evalCast(const CallExpr *CE, DefinedOrUnknownSVal ParamDV,
48 CheckerContext &C) const;
49 void evalDynCast(const CallExpr *CE, DefinedOrUnknownSVal ParamDV,
50 CheckerContext &C) const;
51 void evalCastOrNull(const CallExpr *CE, DefinedOrUnknownSVal ParamDV,
52 CheckerContext &C) const;
53 void evalDynCastOrNull(const CallExpr *CE, DefinedOrUnknownSVal ParamDV,
54 CheckerContext &C) const;
58 static std::string getCastName(const Expr *Cast) {
59 return Cast->getType()->getPointeeCXXRecordDecl()->getNameAsString();
62 static void evalNonNullParamNonNullReturn(const CallExpr *CE,
63 DefinedOrUnknownSVal ParamDV,
65 ProgramStateRef State = C.getState()->assume(ParamDV, true);
69 State = State->BindExpr(CE, C.getLocationContext(), ParamDV, false);
71 std::string CastFromName = getCastName(CE->getArg(0));
72 std::string CastToName = getCastName(CE);
74 const NoteTag *CastTag = C.getNoteTag(
75 [CastFromName, CastToName](BugReport &) -> std::string {
77 llvm::raw_svector_ostream Out(Msg);
79 Out << "Assuming dynamic cast from '" << CastFromName << "' to '"
80 << CastToName << "' succeeds";
85 C.addTransition(State, CastTag);
88 static void evalNonNullParamNullReturn(const CallExpr *CE,
89 DefinedOrUnknownSVal ParamDV,
91 ProgramStateRef State = C.getState()->assume(ParamDV, true);
95 State = State->BindExpr(CE, C.getLocationContext(),
96 C.getSValBuilder().makeNull(), false);
98 std::string CastFromName = getCastName(CE->getArg(0));
99 std::string CastToName = getCastName(CE);
101 const NoteTag *CastTag = C.getNoteTag(
102 [CastFromName, CastToName](BugReport &) -> std::string {
103 SmallString<128> Msg;
104 llvm::raw_svector_ostream Out(Msg);
106 Out << "Assuming dynamic cast from '" << CastFromName << "' to '"
107 << CastToName << "' fails";
110 /*IsPrunable=*/true);
112 C.addTransition(State, CastTag);
115 static void evalNullParamNullReturn(const CallExpr *CE,
116 DefinedOrUnknownSVal ParamDV,
118 ProgramStateRef State = C.getState()->assume(ParamDV, false);
122 State = State->BindExpr(CE, C.getLocationContext(),
123 C.getSValBuilder().makeNull(), false);
125 const NoteTag *CastTag =
126 C.getNoteTag("Assuming null pointer is passed into cast",
127 /*IsPrunable=*/true);
129 C.addTransition(State, CastTag);
132 void CastValueChecker::evalCast(const CallExpr *CE,
133 DefinedOrUnknownSVal ParamDV,
134 CheckerContext &C) const {
135 evalNonNullParamNonNullReturn(CE, ParamDV, C);
138 void CastValueChecker::evalDynCast(const CallExpr *CE,
139 DefinedOrUnknownSVal ParamDV,
140 CheckerContext &C) const {
141 evalNonNullParamNonNullReturn(CE, ParamDV, C);
142 evalNonNullParamNullReturn(CE, ParamDV, C);
145 void CastValueChecker::evalCastOrNull(const CallExpr *CE,
146 DefinedOrUnknownSVal ParamDV,
147 CheckerContext &C) const {
148 evalNonNullParamNonNullReturn(CE, ParamDV, C);
149 evalNullParamNullReturn(CE, ParamDV, C);
152 void CastValueChecker::evalDynCastOrNull(const CallExpr *CE,
153 DefinedOrUnknownSVal ParamDV,
154 CheckerContext &C) const {
155 evalNonNullParamNonNullReturn(CE, ParamDV, C);
156 evalNonNullParamNullReturn(CE, ParamDV, C);
157 evalNullParamNullReturn(CE, ParamDV, C);
160 bool CastValueChecker::evalCall(const CallEvent &Call,
161 CheckerContext &C) const {
162 const CastCheck *Check = CDM.lookup(Call);
166 const auto *CE = cast<CallExpr>(Call.getOriginExpr());
170 // If we cannot obtain both of the classes we cannot be sure how to model it.
171 if (!CE->getType()->getPointeeCXXRecordDecl() ||
172 !CE->getArg(0)->getType()->getPointeeCXXRecordDecl())
175 SVal ParamV = Call.getArgSVal(0);
176 auto ParamDV = ParamV.getAs<DefinedOrUnknownSVal>();
180 (*Check)(this, CE, *ParamDV, C);
184 void ento::registerCastValueChecker(CheckerManager &Mgr) {
185 Mgr.registerChecker<CastValueChecker>();
188 bool ento::shouldRegisterCastValueChecker(const LangOptions &LO) {