clang 19.0.0git
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
26#include "clang/AST/Decl.h"
27#include "clang/AST/DeclObjC.h"
36
37using namespace clang;
38using namespace ento;
39using namespace ast_matchers;
40
41namespace {
42
43const char * RunLoopBind = "NSRunLoopM";
44const char * RunLoopRunBind = "RunLoopRunM";
45const char * OtherMsgBind = "OtherMessageSentM";
46const char * AutoreleasePoolBind = "AutoreleasePoolM";
47const char * OtherStmtAutoreleasePoolBind = "OtherAutoreleasePoolM";
48
49class RunLoopAutoreleaseLeakChecker : public Checker<check::ASTCodeBody> {
50
51public:
52 void checkASTCodeBody(const Decl *D,
54 BugReporter &BR) const;
55
56};
57
58} // end anonymous namespace
59
60/// \return Whether @c A occurs before @c B in traversal of
61/// @c 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.
65static 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
80static void emitDiagnostics(BoundNodes &Match,
81 const Decl *D,
82 BugReporter &BR,
84 const RunLoopAutoreleaseLeakChecker *Checker) {
85
86 assert(D->hasBody());
87 const Stmt *DeclBody = D->getBody();
88
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
113 ME, BR.getSourceManager(), ADC);
114 SourceRange Range = ME->getSourceRange();
115
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
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
148 return objcMessageExpr(unless(anyOf(equalsBoundNode(RunLoopBind),
149 equalsBoundNode(RunLoopRunBind))),
150 Extra)
151 .bind(OtherMsgBind);
152}
153
154static void
156 const RunLoopAutoreleaseLeakChecker *Chkr) {
157 StatementMatcher RunLoopRunM = getRunLoopRunM();
158 StatementMatcher OtherMessageSentM = getOtherMessageSentM(
159 hasAncestor(autoreleasePoolStmt().bind(OtherStmtAutoreleasePoolBind)));
160
161 StatementMatcher RunLoopInAutorelease =
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
173static void
175 const RunLoopAutoreleaseLeakChecker *Chkr) {
176
177 auto NoPoolM = unless(hasAncestor(autoreleasePoolStmt()));
178
179 StatementMatcher RunLoopRunM = getRunLoopRunM(NoPoolM);
180 StatementMatcher OtherMessageSentM = getOtherMessageSentM(NoPoolM);
181
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
195void 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
202void ento::registerRunLoopAutoreleaseLeakChecker(CheckerManager &mgr) {
203 mgr.registerChecker<RunLoopAutoreleaseLeakChecker>();
204}
205
206bool ento::shouldRegisterRunLoopAutoreleaseLeakChecker(const CheckerManager &mgr) {
207 return true;
208}
NodeId Parent
Definition: ASTDiff.cpp:191
static void emitDiagnostics(BoundNodes &Match, const Decl *D, BugReporter &BR, AnalysisManager &AM, const RunLoopAutoreleaseLeakChecker *Checker)
static bool seenBefore(const Stmt *Parent, const Stmt *A, const Stmt *B)
static void checkTempObjectsInSamePool(const Decl *D, AnalysisManager &AM, BugReporter &BR, const RunLoopAutoreleaseLeakChecker *Chkr)
static StatementMatcher getRunLoopRunM(StatementMatcher Extra=anything())
static StatementMatcher getOtherMessageSentM(StatementMatcher Extra=anything())
static void checkTempObjectsInNoPool(const Decl *D, AnalysisManager &AM, BugReporter &BR, const RunLoopAutoreleaseLeakChecker *Chkr)
AnalysisDeclContext contains the context data for the function, method or block under analysis.
const Decl * getDecl() const
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:86
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:1073
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:1079
Represents Objective-C's @autoreleasepool Statement.
Definition: StmtObjC.h:394
An expression that sends a message to the given Objective-C object or class.
Definition: ExprObjC.h:945
A trivial tuple used to represent a source range.
Stmt - This represents one statement.
Definition: Stmt.h:84
Maps string IDs to AST nodes matched by parts of a matcher.
Definition: ASTMatchers.h:109
const T * getNodeAs(StringRef ID) const
Returns the AST node bound to ID.
Definition: ASTMatchers.h:116
ASTContext & getASTContext() override
AnalysisDeclContext * getAnalysisDeclContext(const Decl *D)
BugReporter is a utility class for generating PathDiagnostics for analysis.
Definition: BugReporter.h:585
const SourceManager & getSourceManager()
Definition: BugReporter.h:623
void EmitBasicReport(const Decl *DeclWithIssue, const CheckerBase *Checker, StringRef BugName, StringRef BugCategory, StringRef BugStr, PathDiagnosticLocation Loc, ArrayRef< SourceRange > Ranges=std::nullopt, ArrayRef< FixItHint > Fixits=std::nullopt)
CHECKER * registerChecker(AT &&... Args)
Used to register checkers.
static PathDiagnosticLocation createBegin(const Decl *D, const SourceManager &SM)
Create a location for the beginning of the declaration.
A Range represents the closed range [from, to].
const internal::VariadicOperatorMatcherFunc< 1, 1 > unless
Matches if the provided matcher does not match.
internal::Matcher< Decl > DeclarationMatcher
Types of matchers for the top-level classes in the AST class hierarchy.
Definition: ASTMatchers.h:143
const internal::ArgumentAdaptingMatcherFunc< internal::HasDescendantMatcher > hasDescendant
Matches AST nodes that have descendant AST nodes that match the provided matcher.
internal::Matcher< NamedDecl > hasName(StringRef Name)
Matches NamedDecl nodes that have the specified name.
Definition: ASTMatchers.h:3079
const internal::VariadicDynCastAllOfMatcher< Stmt, CallExpr > callExpr
Matches call expressions.
const internal::VariadicDynCastAllOfMatcher< Stmt, ObjCAutoreleasePoolStmt > autoreleasePoolStmt
Matches an Objective-C autorelease pool statement.
SmallVector< BoundNodes, 1 > match(MatcherT Matcher, const NodeT &Node, ASTContext &Context)
Returns the results of matching Matcher on Node.
internal::TrueMatcher anything()
Matches any node.
Definition: ASTMatchers.h:171
const internal::VariadicDynCastAllOfMatcher< Stmt, ObjCMessageExpr > objcMessageExpr
Matches ObjectiveC Message invocation expressions.
internal::Matcher< Stmt > StatementMatcher
Definition: ASTMatchers.h:144
const internal::VariadicDynCastAllOfMatcher< Decl, FunctionDecl > functionDecl
Matches function declarations.
const internal::VariadicAllOfMatcher< Decl > decl
Matches declarations.
const internal::VariadicOperatorMatcherFunc< 2, std::numeric_limits< unsigned >::max()> anyOf
Matches if any of the given matchers matches.
const internal::ArgumentAdaptingMatcherFunc< internal::HasAncestorMatcher, internal::TypeList< Decl, NestedNameSpecifierLoc, Stmt, TypeLoc, Attr >, internal::TypeList< Decl, NestedNameSpecifierLoc, Stmt, TypeLoc, Attr > > hasAncestor
Matches AST nodes that have an ancestor that matches the provided matcher.
The JSON file list parser is used to communicate input to InstallAPI.