clang 10.0.0git

RunLoopAutoreleaseLeakChecker.cpp
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1 //=- RunLoopAutoreleaseLeakChecker.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 //
10 // A checker for detecting leaks resulting from allocating temporary
11 // autoreleased objects before starting the main run loop.
12 //
13 // Checks for two antipatterns:
14 // 1. ObjCMessageExpr followed by [[NSRunLoop mainRunLoop] run] in the same
15 // autorelease pool.
16 // 2. ObjCMessageExpr followed by [[NSRunLoop mainRunLoop] run] in no
17 // autorelease pool.
18 //
19 // Any temporary objects autoreleased in code called in those expressions
20 // will not be deallocated until the program exits, and are effectively leaks.
21 //
22 //===----------------------------------------------------------------------===//
23 //
24
25 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
26 #include "clang/AST/Decl.h"
27 #include "clang/AST/DeclObjC.h"
28 #include "clang/ASTMatchers/ASTMatchFinder.h"
29 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
30 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
31 #include "clang/StaticAnalyzer/Core/Checker.h"
32 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
33 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
34 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
35 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
36
37 using namespace clang;
38 using namespace ento;
39 using namespace ast_matchers;
40
41 namespace {
42
43 const char * RunLoopBind = "NSRunLoopM";
44 const char * RunLoopRunBind = "RunLoopRunM";
45 const char * OtherMsgBind = "OtherMessageSentM";
46 const char * AutoreleasePoolBind = "AutoreleasePoolM";
47 const char * OtherStmtAutoreleasePoolBind = "OtherAutoreleasePoolM";
48
49 class RunLoopAutoreleaseLeakChecker : public Checker<check::ASTCodeBody> {
50
51 public:
52 void checkASTCodeBody(const Decl *D,
53 AnalysisManager &AM,
54 BugReporter &BR) const;
55
56 };
57
58 } // end anonymous namespace
59
60 /// \return Whether {@code A} occurs before {@code B} in traversal of
61 /// {@code Parent}.
62 /// Conceptually a very incomplete/unsound approximation of happens-before
63 /// relationship (A is likely to be evaluated before B),
64 /// but useful enough in this case.
65 static bool seenBefore(const Stmt *Parent, const Stmt *A, const Stmt *B) {
66 for (const Stmt *C : Parent->children()) {
67 if (!C) continue;
68
69 if (C == A)
70 return true;
71
72 if (C == B)
73 return false;
74
75 return seenBefore(C, A, B);
76 }
77 return false;
78 }
79
80 static void emitDiagnostics(BoundNodes &Match,
81 const Decl *D,
82 BugReporter &BR,
83 AnalysisManager &AM,
84 const RunLoopAutoreleaseLeakChecker *Checker) {
85
86 assert(D->hasBody());
87 const Stmt *DeclBody = D->getBody();
88
89 AnalysisDeclContext *ADC = AM.getAnalysisDeclContext(D);
90
91 const auto *ME = Match.getNodeAs<ObjCMessageExpr>(OtherMsgBind);
92 assert(ME);
93
94 const auto *AP =
95 Match.getNodeAs<ObjCAutoreleasePoolStmt>(AutoreleasePoolBind);
96 const auto *OAP =
97 Match.getNodeAs<ObjCAutoreleasePoolStmt>(OtherStmtAutoreleasePoolBind);
98 bool HasAutoreleasePool = (AP != nullptr);
99
100 const auto *RL = Match.getNodeAs<ObjCMessageExpr>(RunLoopBind);
101 const auto *RLR = Match.getNodeAs<Stmt>(RunLoopRunBind);
102 assert(RLR && "Run loop launch not found");
103 assert(ME != RLR);
104
105 // Launch of run loop occurs before the message-sent expression is seen.
106 if (seenBefore(DeclBody, RLR, ME))
107 return;
108
109 if (HasAutoreleasePool && (OAP != AP))
110 return;
111
112 PathDiagnosticLocation Location = PathDiagnosticLocation::createBegin(
113 ME, BR.getSourceManager(), ADC);
114 SourceRange Range = ME->getSourceRange();
115
116 BR.EmitBasicReport(ADC->getDecl(), Checker,
117 /*Name=*/"Memory leak inside autorelease pool",
118 /*BugCategory=*/"Memory",
119 /*Name=*/
120 (Twine("Temporary objects allocated in the") +
121 " autorelease pool " +
122 (HasAutoreleasePool ? "" : "of last resort ") +
123 "followed by the launch of " +
124 (RL ? "main run loop " : "xpc_main ") +
125 "may never get released; consider moving them to a "
126 "separate autorelease pool")
127 .str(),
128 Location, Range);
129 }
130
131 static StatementMatcher getRunLoopRunM(StatementMatcher Extra = anything()) {
132 StatementMatcher MainRunLoopM =
133 objcMessageExpr(hasSelector("mainRunLoop"),
134 hasReceiverType(asString("NSRunLoop")),
135 Extra)
136 .bind(RunLoopBind);
137
138 StatementMatcher MainRunLoopRunM = objcMessageExpr(hasSelector("run"),
139 hasReceiver(MainRunLoopM),
140 Extra).bind(RunLoopRunBind);
141
142 StatementMatcher XPCRunM =
143 callExpr(callee(functionDecl(hasName("xpc_main")))).bind(RunLoopRunBind);
144 return anyOf(MainRunLoopRunM, XPCRunM);
145 }
146
147 static StatementMatcher getOtherMessageSentM(StatementMatcher Extra = anything()) {
148 return objcMessageExpr(unless(anyOf(equalsBoundNode(RunLoopBind),
149 equalsBoundNode(RunLoopRunBind))),
150 Extra)
151 .bind(OtherMsgBind);
152 }
153
154 static void
155 checkTempObjectsInSamePool(const Decl *D, AnalysisManager &AM, BugReporter &BR,
156 const RunLoopAutoreleaseLeakChecker *Chkr) {
157 StatementMatcher RunLoopRunM = getRunLoopRunM();
158 StatementMatcher OtherMessageSentM = getOtherMessageSentM(
159 hasAncestor(autoreleasePoolStmt().bind(OtherStmtAutoreleasePoolBind)));
160
161 StatementMatcher RunLoopInAutorelease =
162 autoreleasePoolStmt(
163 hasDescendant(RunLoopRunM),
164 hasDescendant(OtherMessageSentM)).bind(AutoreleasePoolBind);
165
166 DeclarationMatcher GroupM = decl(hasDescendant(RunLoopInAutorelease));
167
168 auto Matches = match(GroupM, *D, AM.getASTContext());
169 for (BoundNodes Match : Matches)
170 emitDiagnostics(Match, D, BR, AM, Chkr);
171 }
172
173 static void
174 checkTempObjectsInNoPool(const Decl *D, AnalysisManager &AM, BugReporter &BR,
175 const RunLoopAutoreleaseLeakChecker *Chkr) {
176
177 auto NoPoolM = unless(hasAncestor(autoreleasePoolStmt()));
178
179 StatementMatcher RunLoopRunM = getRunLoopRunM(NoPoolM);
180 StatementMatcher OtherMessageSentM = getOtherMessageSentM(NoPoolM);
181
182 DeclarationMatcher GroupM = functionDecl(
183 isMain(),
184 hasDescendant(RunLoopRunM),
185 hasDescendant(OtherMessageSentM)
186 );
187
188 auto Matches = match(GroupM, *D, AM.getASTContext());
189
190 for (BoundNodes Match : Matches)
191 emitDiagnostics(Match, D, BR, AM, Chkr);
192
193 }
194
195 void RunLoopAutoreleaseLeakChecker::checkASTCodeBody(const Decl *D,
196 AnalysisManager &AM,
197 BugReporter &BR) const {
198 checkTempObjectsInSamePool(D, AM, BR, this);
199 checkTempObjectsInNoPool(D, AM, BR, this);
200 }
201
202 void ento::registerRunLoopAutoreleaseLeakChecker(CheckerManager &mgr) {
203 mgr.registerChecker<RunLoopAutoreleaseLeakChecker>();
204 }
205
206 bool ento::shouldRegisterRunLoopAutoreleaseLeakChecker(const LangOptions &LO) {
207 return true;
208 }
clang::ast_matchers::anything
internal::TrueMatcher anything()
Matches any node.
Definition: ASTMatchers.h:161
ento
clang::ast_matchers::callExpr
const internal::VariadicDynCastAllOfMatcher< Stmt, CallExpr > callExpr
Matches call expressions.
Definition: ASTMatchersInternal.cpp:668
clang::Decl::getBody
virtual Stmt * getBody() const
getBody - If this Decl represents a declaration for a body of code, such as a function or method defi...
Definition: DeclBase.h:986
ASTMatchFinder.h
clang::Stmt
Stmt - This represents one statement.
Definition: Stmt.h:66
clang::ast_matchers::StatementMatcher
internal::Matcher< Stmt > StatementMatcher
Definition: ASTMatchers.h:139
clang::ast_matchers::anyOf
const internal::VariadicOperatorMatcherFunc< 2, std::numeric_limits< unsigned >::max()> anyOf
Matches if any of the given matchers matches.
Definition: ASTMatchersInternal.cpp:820
clang::Decl
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:88
clang::ast_matchers::hasDescendant
const internal::ArgumentAdaptingMatcherFunc< internal::HasDescendantMatcher > hasDescendant
Matches AST nodes that have descendant AST nodes that match the provided matcher. ...
Definition: ASTMatchersInternal.cpp:835
DeclObjC.h
BugType.h
clang::ast_matchers::functionDecl
const internal::VariadicDynCastAllOfMatcher< Decl, FunctionDecl > functionDecl
Matches function declarations.
Definition: ASTMatchersInternal.cpp:657
ExprEngine.h
clang::AnalysisDeclContext
AnalysisDeclContext contains the context data for the function or method under analysis.
Definition: AnalysisDeclContext.h:69
Checker.h
CheckerManager.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::ast_matchers::BoundNodes::getNodeAs
const T * getNodeAs(StringRef ID) const
Returns the AST node bound to ID.
Definition: ASTMatchers.h:111
clang::Stmt::children
child_range children()
Definition: Stmt.cpp:224
clang::ast_matchers::match
SmallVector< BoundNodes, 1 > match(MatcherT Matcher, const NodeT &Node, ASTContext &Context)
Returns the results of matching Matcher on Node.
Definition: ASTMatchFinder.h:298
Parent
NodeId Parent
Definition: ASTDiff.cpp:191
BugReporter.h
clang::ast_matchers::autoreleasePoolStmt
const internal::VariadicDynCastAllOfMatcher< Stmt, ObjCAutoreleasePoolStmt > autoreleasePoolStmt
Matches an Objective-C autorelease pool statement.
Definition: ASTMatchersInternal.cpp:598
clang::ast_matchers::decl
const internal::VariadicAllOfMatcher< Decl > decl
Matches declarations.
Definition: ASTMatchersInternal.cpp:607
clang::ObjCMessageExpr
An expression that sends a message to the given Objective-C object or class.
Definition: ExprObjC.h:950
BuiltinCheckerRegistration.h
clang::ast_matchers::hasAncestor
const internal::ArgumentAdaptingMatcherFunc< internal::HasAncestorMatcher, internal::TypeList< Decl, NestedNameSpecifierLoc, Stmt, TypeLoc >, internal::TypeList< Decl, NestedNameSpecifierLoc, Stmt, TypeLoc > > hasAncestor
Matches AST nodes that have an ancestor that matches the provided matcher.
Definition: ASTMatchersInternal.cpp:849
clang::Decl::hasBody
virtual bool hasBody() const
Returns true if this Decl represents a declaration for a body of code, such as a function or method d...
Definition: DeclBase.h:992
clang::ast_matchers::BoundNodes
Maps string IDs to AST nodes matched by parts of a matcher.
Definition: ASTMatchers.h:104
clang::ento::PathDiagnosticLocation::createBegin
static PathDiagnosticLocation createBegin(const Decl *D, const SourceManager &SM)
Create a location for the beginning of the declaration.
Definition: PathDiagnostic.cpp:564
clang::Decl::getASTContext
ASTContext & getASTContext() const LLVM_READONLY
Definition: DeclBase.cpp:377
clang::AnalysisDeclContext::getDecl
const Decl * getDecl() const
Definition: AnalysisDeclContext.h:104
emitDiagnostics
static void emitDiagnostics(BoundNodes &Match, const Decl *D, BugReporter &BR, AnalysisManager &AM, const ObjCAutoreleaseWriteChecker *Checker)
Definition: ObjCAutoreleaseWriteChecker.cpp:108
clang::ast_matchers::unless
const internal::VariadicOperatorMatcherFunc< 1, 1 > unless
Matches if the provided matcher does not match.
Definition: ASTMatchersInternal.cpp:850
Decl.h
clang
Dataflow Directional Tag Classes.
Definition: CFGReachabilityAnalysis.h:21
ast_matchers
clang::ast_matchers::hasName
internal::Matcher< NamedDecl > hasName(const std::string &Name)
Matches NamedDecl nodes that have the specified name.
Definition: ASTMatchers.h:2649
clang::SourceRange
A trivial tuple used to represent a source range.
Definition: SourceLocation.h:207
clang::ast_matchers::objcMessageExpr
const internal::VariadicDynCastAllOfMatcher< Stmt, ObjCMessageExpr > objcMessageExpr
Matches ObjectiveC Message invocation expressions.
Definition: ASTMatchersInternal.cpp:673
CallEvent.h
clang::ObjCAutoreleasePoolStmt
Represents Objective-C&#39;s @autoreleasepool Statement.
Definition: StmtObjC.h:368
CheckerContext.h
clang::ast_matchers::DeclarationMatcher
internal::Matcher< Decl > DeclarationMatcher
Types of matchers for the top-level classes in the AST class hierarchy.
Definition: ASTMatchers.h:138