ObjCAtSyncChecker.cpp source code [clang_source_code/lib/StaticAnalyzer/Checkers/ObjCAtSyncChecker.cpp]

1	//== ObjCAtSyncChecker.cpp - nil mutex checker for @synchronized -- 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 defines ObjCAtSyncChecker, a builtin check that checks for null pointers
10	// used as mutexes for @synchronized.
11	//
12	//===----------------------------------------------------------------------===//
13
14	#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
15	#include "clang/AST/StmtObjC.h"
16	#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
17	#include "clang/StaticAnalyzer/Core/Checker.h"
18	#include "clang/StaticAnalyzer/Core/CheckerManager.h"
19	#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
20	#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
21
22	using namespace clang;
23	using namespace ento;
24
25	namespace {
26	class ObjCAtSyncChecker
27	: public Checker< check::PreStmt<ObjCAtSynchronizedStmt> > {
28	mutable std::unique_ptr<BuiltinBug> BT_null;
29	mutable std::unique_ptr<BuiltinBug> BT_undef;
30
31	public:
32	void checkPreStmt(const ObjCAtSynchronizedStmt *S, CheckerContext &C) const;
33	};
34	} // end anonymous namespace
35
36	void ObjCAtSyncChecker::checkPreStmt(const ObjCAtSynchronizedStmt *S,
37	CheckerContext &C) const {
38
39	const Expr *Ex = S->getSynchExpr();
40	ProgramStateRef state = C.getState();
41	SVal V = C.getSVal(Ex);
42
43	// Uninitialized value used for the mutex?
44	if (V.getAs<UndefinedVal>()) {
45	if (ExplodedNode *N = C.generateErrorNode()) {
46	if (!BT_undef)
47	BT_undef.reset(new BuiltinBug(this, "Uninitialized value used as mutex "
48	"for @synchronized"));
49	auto report =
50	llvm::make_unique<BugReport>(*BT_undef, BT_undef->getDescription(), N);
51	bugreporter::trackExpressionValue(N, Ex, *report);
52	C.emitReport(std::move(report));
53	}
54	return;
55	}
56
57	if (V.isUnknown())
58	return;
59
60	// Check for null mutexes.
61	ProgramStateRef notNullState, nullState;
62	std::tie(notNullState, nullState) = state->assume(V.castAs<DefinedSVal>());
63
64	if (nullState) {
65	if (!notNullState) {
66	// Generate an error node. This isn't a sink since
67	// a null mutex just means no synchronization occurs.
68	if (ExplodedNode *N = C.generateNonFatalErrorNode(nullState)) {
69	if (!BT_null)
70	BT_null.reset(new BuiltinBug(
71	this, "Nil value used as mutex for @synchronized() "
72	"(no synchronization will occur)"));
73	auto report =
74	llvm::make_unique<BugReport>(*BT_null, BT_null->getDescription(), N);
75	bugreporter::trackExpressionValue(N, Ex, *report);
76
77	C.emitReport(std::move(report));
78	return;
79	}
80	}
81	// Don't add a transition for 'nullState'. If the value is
82	// under-constrained to be null or non-null, assume it is non-null
83	// afterwards.
84	}
85
86	if (notNullState)
87	C.addTransition(notNullState);
88	}
89
90	void ento::registerObjCAtSyncChecker(CheckerManager &mgr) {
91	mgr.registerChecker<ObjCAtSyncChecker>();
92	}
93
94	bool ento::shouldRegisterObjCAtSyncChecker(const LangOptions &LO) {
95	return LO.ObjC;
96	}
97

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