Merge branch 'master' of ssh://bitbucket.org/czan/honours

1 files changed, 96 insertions, 0 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
new file mode 100644
index 0000000..2627f0c
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/DivZeroChecker.cpp
@@ -0,0 +1,96 @@
+//== DivZeroChecker.cpp - Division by zero checker --------------*- C++ -*--==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This defines DivZeroChecker, a builtin check in ExprEngine that performs
+// checks for division by zeros.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/CheckerManager.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+class DivZeroChecker : public Checker< check::PreStmt<BinaryOperator> > {
+  mutable OwningPtr<BuiltinBug> BT;
+  void reportBug(const char *Msg,
+                 ProgramStateRef StateZero,
+                 CheckerContext &C) const ;
+public:
+  void checkPreStmt(const BinaryOperator *B, CheckerContext &C) const;
+};  
+} // end anonymous namespace
+
+void DivZeroChecker::reportBug(const char *Msg,
+                               ProgramStateRef StateZero,
+                               CheckerContext &C) const {
+  if (ExplodedNode *N = C.generateSink(StateZero)) {
+    if (!BT)
+      BT.reset(new BuiltinBug("Division by zero"));
+
+    BugReport *R =
+      new BugReport(*BT, Msg, N);
+
+    R->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N,
+                                 bugreporter::GetDenomExpr(N), R));
+    C.EmitReport(R);
+  }
+}
+
+void DivZeroChecker::checkPreStmt(const BinaryOperator *B,
+                                  CheckerContext &C) const {
+  BinaryOperator::Opcode Op = B->getOpcode();
+  if (Op != BO_Div &&
+      Op != BO_Rem &&
+      Op != BO_DivAssign &&
+      Op != BO_RemAssign)
+    return;
+
+  if (!B->getRHS()->getType()->isIntegerType() ||
+      !B->getRHS()->getType()->isScalarType())
+    return;
+
+  SVal Denom = C.getState()->getSVal(B->getRHS(), C.getLocationContext());
+  const DefinedSVal *DV = dyn_cast<DefinedSVal>(&Denom);
+
+  // Divide-by-undefined handled in the generic checking for uses of
+  // undefined values.
+  if (!DV)
+    return;
+
+  // Check for divide by zero.
+  ConstraintManager &CM = C.getConstraintManager();
+  ProgramStateRef stateNotZero, stateZero;
+  llvm::tie(stateNotZero, stateZero) = CM.assumeDual(C.getState(), *DV);
+
+  if (!stateNotZero) {
+    assert(stateZero);
+    reportBug("Division by zero", stateZero, C);
+    return;
+  }
+
+  bool TaintedD = C.getState()->isTainted(*DV);
+  if ((stateNotZero && stateZero && TaintedD)) {
+    reportBug("Division by a tainted value, possibly zero", stateZero, C);
+    return;
+  }
+
+  // If we get here, then the denom should not be zero. We abandon the implicit
+  // zero denom case for now.
+  C.addTransition(stateNotZero);
+}
+
+void ento::registerDivZeroChecker(CheckerManager &mgr) {
+  mgr.registerChecker<DivZeroChecker>();
+}