clang 10.0.0git

GTestChecker.cpp
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1 //==- GTestChecker.cpp - Model gtest API --*- 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 checker models the behavior of un-inlined APIs from the gtest
10 // unit-testing library to avoid false positives when using assertions from
11 // that library.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
16 #include "clang/AST/Expr.h"
17 #include "clang/Basic/LangOptions.h"
18 #include "clang/StaticAnalyzer/Core/Checker.h"
19 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
22 #include "llvm/Support/raw_ostream.h"
23
24 using namespace clang;
25 using namespace ento;
26
27 // Modeling of un-inlined AssertionResult constructors
28 //
29 // The gtest unit testing API provides macros for assertions that expand
30 // into an if statement that calls a series of constructors and returns
31 // when the "assertion" is false.
32 //
33 // For example,
34 //
35 // ASSERT_TRUE(a == b)
36 //
37 // expands into:
38 //
39 // switch (0)
40 // case 0:
41 // default:
42 // if (const ::testing::AssertionResult gtest_ar_ =
43 // ::testing::AssertionResult((a == b)))
44 // ;
45 // else
46 // return ::testing::internal::AssertHelper(
47 // ::testing::TestPartResult::kFatalFailure,
48 // "<path to project>",
49 // <line number>,
50 // ::testing::internal::GetBoolAssertionFailureMessage(
51 // gtest_ar_, "a == b", "false", "true")
52 // .c_str()) = ::testing::Message();
53 //
54 // where AssertionResult is defined similarly to
55 //
56 // class AssertionResult {
57 // public:
58 // AssertionResult(const AssertionResult& other);
59 // explicit AssertionResult(bool success) : success_(success) {}
60 // operator bool() const { return success_; }
61 // ...
62 // private:
63 // bool success_;
64 // };
65 //
66 // In order for the analyzer to correctly handle this assertion, it needs to
67 // know that the boolean value of the expression "a == b" is stored the
68 // 'success_' field of the original AssertionResult temporary and propagated
69 // (via the copy constructor) into the 'success_' field of the object stored
70 // in 'gtest_ar_'. That boolean value will then be returned from the bool
71 // conversion method in the if statement. This guarantees that the assertion
72 // holds when the return path is not taken.
73 //
74 // If the success value is not properly propagated, then the eager case split
75 // on evaluating the expression can cause pernicious false positives
76 // on the non-return path:
77 //
78 // ASSERT(ptr != NULL)
79 // *ptr = 7; // False positive null pointer dereference here
80 //
81 // Unfortunately, the bool constructor cannot be inlined (because its
82 // implementation is not present in the headers) and the copy constructor is
83 // not inlined (because it is constructed into a temporary and the analyzer
84 // does not inline these since it does not yet reliably call temporary
85 // destructors).
86 //
87 // This checker compensates for the missing inlining by propagating the
88 // _success value across the bool and copy constructors so the assertion behaves
89 // as expected.
90
91 namespace {
92 class GTestChecker : public Checker<check::PostCall> {
93
94 mutable IdentifierInfo *AssertionResultII;
95 mutable IdentifierInfo *SuccessII;
96
97 public:
98 GTestChecker();
99
100 void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
101
102 private:
103 void modelAssertionResultBoolConstructor(const CXXConstructorCall *Call,
104 bool IsRef, CheckerContext &C) const;
105
106 void modelAssertionResultCopyConstructor(const CXXConstructorCall *Call,
107 CheckerContext &C) const;
108
109 void initIdentifierInfo(ASTContext &Ctx) const;
110
111 SVal
112 getAssertionResultSuccessFieldValue(const CXXRecordDecl *AssertionResultDecl,
113 SVal Instance,
114 ProgramStateRef State) const;
115
116 static ProgramStateRef assumeValuesEqual(SVal Val1, SVal Val2,
117 ProgramStateRef State,
118 CheckerContext &C);
119 };
120 } // End anonymous namespace.
121
122 GTestChecker::GTestChecker() : AssertionResultII(nullptr), SuccessII(nullptr) {}
123
124 /// Model a call to an un-inlined AssertionResult(bool) or
125 /// AssertionResult(bool &, ...).
126 /// To do so, constrain the value of the newly-constructed instance's 'success_'
127 /// field to be equal to the passed-in boolean value.
128 ///
129 /// \param IsRef Whether the boolean parameter is a reference or not.
130 void GTestChecker::modelAssertionResultBoolConstructor(
131 const CXXConstructorCall *Call, bool IsRef, CheckerContext &C) const {
132 assert(Call->getNumArgs() >= 1 && Call->getNumArgs() <= 2);
133
134 ProgramStateRef State = C.getState();
135 SVal BooleanArgVal = Call->getArgSVal(0);
136 if (IsRef) {
137 // The argument is a reference, so load from it to get the boolean value.
138 if (!BooleanArgVal.getAs<Loc>())
139 return;
140 BooleanArgVal = C.getState()->getSVal(BooleanArgVal.castAs<Loc>());
141 }
142
143 SVal ThisVal = Call->getCXXThisVal();
144
145 SVal ThisSuccess = getAssertionResultSuccessFieldValue(
146 Call->getDecl()->getParent(), ThisVal, State);
147
148 State = assumeValuesEqual(ThisSuccess, BooleanArgVal, State, C);
149 C.addTransition(State);
150 }
151
152 /// Model a call to an un-inlined AssertionResult copy constructor:
153 ///
154 /// AssertionResult(const &AssertionResult other)
155 ///
156 /// To do so, constrain the value of the newly-constructed instance's
157 /// 'success_' field to be equal to the value of the pass-in instance's
158 /// 'success_' field.
159 void GTestChecker::modelAssertionResultCopyConstructor(
160 const CXXConstructorCall *Call, CheckerContext &C) const {
161 assert(Call->getNumArgs() == 1);
162
163 // The first parameter of the copy constructor must be the other
164 // instance to initialize this instances fields from.
165 SVal OtherVal = Call->getArgSVal(0);
166 SVal ThisVal = Call->getCXXThisVal();
167
168 const CXXRecordDecl *AssertResultClassDecl = Call->getDecl()->getParent();
169 ProgramStateRef State = C.getState();
170
171 SVal ThisSuccess = getAssertionResultSuccessFieldValue(AssertResultClassDecl,
172 ThisVal, State);
173 SVal OtherSuccess = getAssertionResultSuccessFieldValue(AssertResultClassDecl,
174 OtherVal, State);
175
176 State = assumeValuesEqual(ThisSuccess, OtherSuccess, State, C);
177 C.addTransition(State);
178 }
179
180 /// Model calls to AssertionResult constructors that are not inlined.
181 void GTestChecker::checkPostCall(const CallEvent &Call,
182 CheckerContext &C) const {
183 /// If the constructor was inlined, there is no need model it.
184 if (C.wasInlined)
185 return;
186
187 initIdentifierInfo(C.getASTContext());
188
189 auto *CtorCall = dyn_cast<CXXConstructorCall>(&Call);
190 if (!CtorCall)
191 return;
192
193 const CXXConstructorDecl *CtorDecl = CtorCall->getDecl();
194 const CXXRecordDecl *CtorParent = CtorDecl->getParent();
195 if (CtorParent->getIdentifier() != AssertionResultII)
196 return;
197
198 unsigned ParamCount = CtorDecl->getNumParams();
199
200 // Call the appropriate modeling method based the parameters and their
201 // types.
202
203 // We have AssertionResult(const &AssertionResult)
204 if (CtorDecl->isCopyConstructor() && ParamCount == 1) {
205 modelAssertionResultCopyConstructor(CtorCall, C);
206 return;
207 }
208
209 // There are two possible boolean constructors, depending on which
210 // version of gtest is being used:
211 //
212 // v1.7 and earlier:
213 // AssertionResult(bool success)
214 //
215 // v1.8 and greater:
216 // template <typename T>
217 // AssertionResult(const T& success,
218 // typename internal::EnableIf<
219 // !internal::ImplicitlyConvertible<T,
220 // AssertionResult>::value>::type*)
221 //
222 CanQualType BoolTy = C.getASTContext().BoolTy;
223 if (ParamCount == 1 && CtorDecl->getParamDecl(0)->getType() == BoolTy) {
224 // We have AssertionResult(bool)
225 modelAssertionResultBoolConstructor(CtorCall, /*IsRef=*/false, C);
226 return;
227 }
228 if (ParamCount == 2){
229 auto *RefTy = CtorDecl->getParamDecl(0)->getType()->getAs<ReferenceType>();
230 if (RefTy &&
231 RefTy->getPointeeType()->getCanonicalTypeUnqualified() == BoolTy) {
232 // We have AssertionResult(bool &, ...)
233 modelAssertionResultBoolConstructor(CtorCall, /*IsRef=*/true, C);
234 return;
235 }
236 }
237 }
238
239 void GTestChecker::initIdentifierInfo(ASTContext &Ctx) const {
240 if (AssertionResultII)
241 return;
242
243 AssertionResultII = &Ctx.Idents.get("AssertionResult");
244 SuccessII = &Ctx.Idents.get("success_");
245 }
246
247 /// Returns the value stored in the 'success_' field of the passed-in
248 /// AssertionResult instance.
249 SVal GTestChecker::getAssertionResultSuccessFieldValue(
250 const CXXRecordDecl *AssertionResultDecl, SVal Instance,
251 ProgramStateRef State) const {
252
253 DeclContext::lookup_result Result = AssertionResultDecl->lookup(SuccessII);
254 if (Result.empty())
255 return UnknownVal();
256
257 auto *SuccessField = dyn_cast<FieldDecl>(Result.front());
258 if (!SuccessField)
259 return UnknownVal();
260
261 Optional<Loc> FieldLoc =
262 State->getLValue(SuccessField, Instance).getAs<Loc>();
263 if (!FieldLoc.hasValue())
264 return UnknownVal();
265
266 return State->getSVal(*FieldLoc);
267 }
268
269 /// Constrain the passed-in state to assume two values are equal.
270 ProgramStateRef GTestChecker::assumeValuesEqual(SVal Val1, SVal Val2,
271 ProgramStateRef State,
272 CheckerContext &C) {
273 if (!Val1.getAs<DefinedOrUnknownSVal>() ||
274 !Val2.getAs<DefinedOrUnknownSVal>())
275 return State;
276
277 auto ValuesEqual =
278 C.getSValBuilder().evalEQ(State, Val1.castAs<DefinedOrUnknownSVal>(),
279 Val2.castAs<DefinedOrUnknownSVal>());
280
281 if (!ValuesEqual.getAs<DefinedSVal>())
282 return State;
283
284 State = C.getConstraintManager().assume(
285 State, ValuesEqual.castAs<DefinedSVal>(), true);
286
287 return State;
288 }
289
290 void ento::registerGTestChecker(CheckerManager &Mgr) {
291 Mgr.registerChecker<GTestChecker>();
292 }
293
294 bool ento::shouldRegisterGTestChecker(const LangOptions &LO) {
295 // gtest is a C++ API so there is no sense running the checker
296 // if not compiling for C++.
297 return LO.CPlusPlus;
298 }
ento
clang::CXXConstructorCall::getDecl
const CXXConstructorDecl * getDecl() const override
Definition: CallEvent.h:846
clang::ento::ProgramStateRef
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
Definition: ProgramState_Fwd.h:37
clang::CXXConstructorDecl
Represents a C++ constructor within a class.
Definition: DeclCXX.h:2383
clang::Type::getAs
const T * getAs() const
Member-template getAs<specific type>&#39;.
Definition: Type.h:7002
clang::DeclContextLookupResult::front
reference front() const
Definition: DeclBase.h:1242
clang::NamedDecl::getIdentifier
IdentifierInfo * getIdentifier() const
Get the identifier that names this declaration, if there is one.
Definition: Decl.h:244
clang::IdentifierInfo
One of these records is kept for each identifier that is lexed.
Definition: IdentifierTable.h:57
clang::ASTContext
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:168
llvm::Optional
Definition: LLVM.h:37
clang::DeclContextLookupResult
The results of name lookup within a DeclContext.
Definition: DeclBase.h:1195
State
LineState State
Definition: UnwrappedLineFormatter.cpp:932
clang::FieldDecl
Represents a member of a struct/union/class.
Definition: Decl.h:2729
Checker.h
clang::LangOptions
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:53
clang::ASTContext::Idents
IdentifierTable & Idents
Definition: ASTContext.h:580
clang::DeclContext::lookup
lookup_result lookup(DeclarationName Name) const
lookup - Find the declarations (if any) with the given Name in this context.
Definition: DeclBase.cpp:1612
LangOptions.h
Defines the clang::LangOptions interface.
clang::CXXConstructorCall::getNumArgs
unsigned getNumArgs() const override
Definition: CallEvent.h:850
ProgramState.h
BuiltinCheckerRegistration.h
clang::IdentifierTable::get
IdentifierInfo & get(StringRef Name)
Return the identifier token info for the specified named identifier.
Definition: IdentifierTable.h:529
clang::FunctionDecl::getParamDecl
const ParmVarDecl * getParamDecl(unsigned i) const
Definition: Decl.h:2422
clang::CanQual< Type >
clang::CXXConstructorCall::getCXXThisVal
SVal getCXXThisVal() const
Returns the value of the implicit &#39;this&#39; object.
Definition: CallEvent.cpp:892
clang
Dataflow Directional Tag Classes.
Definition: CFGReachabilityAnalysis.h:21
clang::CXXConstructorDecl::isCopyConstructor
bool isCopyConstructor(unsigned &TypeQuals) const
Whether this constructor is a copy constructor (C++ [class.copy]p2, which can be used to copy the cla...
Definition: DeclCXX.cpp:2529
clang::CXXMethodDecl::getParent
const CXXRecordDecl * getParent() const
Return the parent of this method declaration, which is the class in which this method is defined...
Definition: DeclCXX.h:2046
clang::ReferenceType
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2750
clang::CXXRecordDecl
Represents a C++ struct/union/class.
Definition: DeclCXX.h:253
Expr.h
AttributeLangSupport::C
Definition: SemaDeclAttr.cpp:45
clang::ValueDecl::getType
QualType getType() const
Definition: Decl.h:630
clang::DeclContextLookupResult::empty
bool empty() const
Definition: DeclBase.h:1239
CallEvent.h
clang::FunctionDecl::getNumParams
unsigned getNumParams() const
Return the number of parameters this function must have based on its FunctionType.
Definition: Decl.cpp:3242
CallEvent
clang::CXXConstructorCall
Represents a call to a C++ constructor.
Definition: CallEvent.h:817
CheckerContext.h