1//== BoolAssignmentChecker.cpp - Boolean assignment checker -----*- 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 BoolAssignmentChecker, a builtin check in ExprEngine that
10// performs checks for assignment of non-Boolean values to Boolean variables.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
15#include "clang/StaticAnalyzer/Checkers/Taint.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 <optional>
21
22using namespace clang;
23using namespace ento;
24
25namespace {
26class BoolAssignmentChecker : public Checker<check::Bind> {
27 const BugType BT{this, "Assignment of a non-Boolean value"};
28 void emitReport(ProgramStateRef State, CheckerContext &C,
29 bool IsTainted = false) const;
30
31public:
32 void checkBind(SVal Loc, SVal Val, const Stmt *S, CheckerContext &C) const;
33};
34} // end anonymous namespace
35
36void BoolAssignmentChecker::emitReport(ProgramStateRef State, CheckerContext &C,
37 bool IsTainted) const {
38 if (ExplodedNode *N = C.generateNonFatalErrorNode(State)) {
39 StringRef Msg = IsTainted ? "Might assign a tainted non-Boolean value"
40 : "Assignment of a non-Boolean value";
41 C.emitReport(R: std::make_unique<PathSensitiveBugReport>(args: BT, args&: Msg, args&: N));
42 }
43}
44
45static bool isBooleanType(QualType Ty) {
46 if (Ty->isBooleanType()) // C++ or C99
47 return true;
48
49 if (const TypedefType *TT = Ty->getAs<TypedefType>())
50 return TT->getDecl()->getName() == "BOOL" || // Objective-C
51 TT->getDecl()->getName() == "_Bool" || // stdbool.h < C99
52 TT->getDecl()->getName() == "Boolean"; // MacTypes.h
53
54 return false;
55}
56
57void BoolAssignmentChecker::checkBind(SVal Loc, SVal Val, const Stmt *S,
58 CheckerContext &C) const {
59
60 // We are only interested in stores into Booleans.
61 const TypedValueRegion *TR =
62 dyn_cast_or_null<TypedValueRegion>(Val: Loc.getAsRegion());
63
64 if (!TR)
65 return;
66
67 QualType RegTy = TR->getValueType();
68
69 if (!isBooleanType(Ty: RegTy))
70 return;
71
72 // Get the value of the right-hand side. We only care about values
73 // that are defined (UnknownVals and UndefinedVals are handled by other
74 // checkers).
75 std::optional<NonLoc> NV = Val.getAs<NonLoc>();
76 if (!NV)
77 return;
78
79 // Check if the assigned value meets our criteria for correctness. It must
80 // be a value that is either 0 or 1. One way to check this is to see if
81 // the value is possibly < 0 (for a negative value) or greater than 1.
82 ProgramStateRef State = C.getState();
83 BasicValueFactory &BVF = C.getSValBuilder().getBasicValueFactory();
84 ConstraintManager &CM = C.getConstraintManager();
85
86 llvm::APSInt Zero = BVF.getValue(X: 0, T: RegTy);
87 llvm::APSInt One = BVF.getValue(X: 1, T: RegTy);
88
89 ProgramStateRef StIn, StOut;
90 std::tie(args&: StIn, args&: StOut) = CM.assumeInclusiveRangeDual(State, Value: *NV, From: Zero, To: One);
91
92 if (!StIn)
93 emitReport(State: StOut, C);
94 if (StIn && StOut && taint::isTainted(State, V: *NV))
95 emitReport(State: StOut, C, /*IsTainted=*/true);
96}
97
98void ento::registerBoolAssignmentChecker(CheckerManager &Mgr) {
99 Mgr.registerChecker<BoolAssignmentChecker>();
100}
101
102bool ento::shouldRegisterBoolAssignmentChecker(const CheckerManager &Mgr) {
103 return true;
104}
105

source code of clang/lib/StaticAnalyzer/Checkers/BoolAssignmentChecker.cpp