lib/Checker/UndefResultChecker.cpp

   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 GRExprEngine that
  11 // performs checks for undefined results of non-assignment binary operators.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "GRExprEngineInternalChecks.h"
  16 #include "clang/GR/BugReporter/BugType.h"
  17 #include "clang/GR/PathSensitive/CheckerVisitor.h"
  18 #include "clang/GR/PathSensitive/GRExprEngine.h"
  19
  20 using namespace clang;
  21
  22 namespace {
  23 class UndefResultChecker
  24   : public CheckerVisitor<UndefResultChecker> {
  25
  26   BugType *BT;
  27
  28 public:
  29   UndefResultChecker() : BT(0) {}
  30   static void *getTag() { static int tag = 0; return &tag; }
  31   void PostVisitBinaryOperator(CheckerContext &C, const BinaryOperator *B);
  32 };
  33 } // end anonymous namespace
  34
  35 void clang::RegisterUndefResultChecker(GRExprEngine &Eng) {
  36   Eng.registerCheck(new UndefResultChecker());
  37 }
  38
  39 void UndefResultChecker::PostVisitBinaryOperator(CheckerContext &C,
  40                                                  const BinaryOperator *B) {
  41   const GRState *state = C.getState();
  42   if (state->getSVal(B).isUndef()) {
  43     // Generate an error node.
  44     ExplodedNode *N = C.generateSink();
  45     if (!N)
  46       return;
  47
  48     if (!BT)
  49       BT = new BuiltinBug("Result of operation is garbage or undefined");
  50
  51     llvm::SmallString<256> sbuf;
  52     llvm::raw_svector_ostream OS(sbuf);
  53     const Expr *Ex = NULL;
  54     bool isLeft = true;
  55
  56     if (state->getSVal(B->getLHS()).isUndef()) {
  57       Ex = B->getLHS()->IgnoreParenCasts();
  58       isLeft = true;
  59     }
  60     else if (state->getSVal(B->getRHS()).isUndef()) {
  61       Ex = B->getRHS()->IgnoreParenCasts();
  62       isLeft = false;
  63     }
  64
  65     if (Ex) {
  66       OS << "The " << (isLeft ? "left" : "right")
  67          << " operand of '"
  68          << BinaryOperator::getOpcodeStr(B->getOpcode())
  69          << "' is a garbage value";
  70     }
  71     else {
  72       // Neither operand was undefined, but the result is undefined.
  73       OS << "The result of the '"
  74          << BinaryOperator::getOpcodeStr(B->getOpcode())
  75          << "' expression is undefined";
  76     }
  77     EnhancedBugReport *report = new EnhancedBugReport(*BT, OS.str(), N);
  78     if (Ex) {
  79       report->addRange(Ex->getSourceRange());
  80       report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, Ex);
  81     }
  82     else
  83       report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, B);
  84     C.EmitReport(report);
  85   }
  86 }