1 //=== UndefResultChecker.cpp ------------------------------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This defines UndefResultChecker, a builtin check in ExprEngine that
11 // performs checks for undefined results of non-assignment binary operators.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "ClangSACheckers.h"
16 #include "clang/StaticAnalyzer/Core/Checker.h"
17 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
19 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
21 #include "llvm/ADT/SmallString.h"
22
23 using namespace clang;
24 using namespace ento;
25
26 namespace {
27 class UndefResultChecker
28 : public Checker< check::PostStmt<BinaryOperator> > {
29
30 mutable OwningPtr<BugType> BT;
31
32 public:
33 void checkPostStmt(const BinaryOperator *B, CheckerContext &C) const;
34 };
35 } // end anonymous namespace
36
checkPostStmt(const BinaryOperator * B,CheckerContext & C) const37 void UndefResultChecker::checkPostStmt(const BinaryOperator *B,
38 CheckerContext &C) const {
39 ProgramStateRef state = C.getState();
40 const LocationContext *LCtx = C.getLocationContext();
41 if (state->getSVal(B, LCtx).isUndef()) {
42 // Generate an error node.
43 ExplodedNode *N = C.generateSink();
44 if (!N)
45 return;
46
47 if (!BT)
48 BT.reset(new BuiltinBug("Result of operation is garbage or undefined"));
49
50 SmallString<256> sbuf;
51 llvm::raw_svector_ostream OS(sbuf);
52 const Expr *Ex = NULL;
53 bool isLeft = true;
54
55 if (state->getSVal(B->getLHS(), LCtx).isUndef()) {
56 Ex = B->getLHS()->IgnoreParenCasts();
57 isLeft = true;
58 }
59 else if (state->getSVal(B->getRHS(), LCtx).isUndef()) {
60 Ex = B->getRHS()->IgnoreParenCasts();
61 isLeft = false;
62 }
63
64 if (Ex) {
65 OS << "The " << (isLeft ? "left" : "right")
66 << " operand of '"
67 << BinaryOperator::getOpcodeStr(B->getOpcode())
68 << "' is a garbage value";
69 }
70 else {
71 // Neither operand was undefined, but the result is undefined.
72 OS << "The result of the '"
73 << BinaryOperator::getOpcodeStr(B->getOpcode())
74 << "' expression is undefined";
75 }
76 BugReport *report = new BugReport(*BT, OS.str(), N);
77 if (Ex) {
78 report->addRange(Ex->getSourceRange());
79 bugreporter::trackNullOrUndefValue(N, Ex, *report);
80 }
81 else
82 bugreporter::trackNullOrUndefValue(N, B, *report);
83
84 C.EmitReport(report);
85 }
86 }
87
registerUndefResultChecker(CheckerManager & mgr)88 void ento::registerUndefResultChecker(CheckerManager &mgr) {
89 mgr.registerChecker<UndefResultChecker>();
90 }
91