1 files changed, 100 insertions, 0 deletions
diff --git a/lib/StaticAnalyzer/Checkers/ObjCAtSyncChecker.cpp b/lib/StaticAnalyzer/Checkers/ObjCAtSyncChecker.cpp
new file mode 100644
index 0000000..7d440ab
--- /dev/null
+++ b/lib/StaticAnalyzer/Checkers/ObjCAtSyncChecker.cpp
@@ -0,0 +1,100 @@
+//== ObjCAtSyncChecker.cpp - nil mutex checker for @synchronized -*- C++ -*--=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This defines ObjCAtSyncChecker, a builtin check that checks for null pointers
+// used as mutexes for @synchronized.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/CheckerManager.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+#include "clang/StaticAnalyzer/Checkers/DereferenceChecker.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerVisitor.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+class ObjCAtSyncChecker : public CheckerVisitor<ObjCAtSyncChecker> {
+  BuiltinBug *BT_null;
+  BuiltinBug *BT_undef;
+public:
+  ObjCAtSyncChecker() : BT_null(0), BT_undef(0) {}
+  static void *getTag() { static int tag = 0; return &tag; }
+  void PreVisitObjCAtSynchronizedStmt(CheckerContext &C,
+                                      const ObjCAtSynchronizedStmt *S);
+};
+} // end anonymous namespace
+
+static void RegisterObjCAtSyncChecker(ExprEngine &Eng) {
+  // @synchronized is an Objective-C 2 feature.
+  if (Eng.getContext().getLangOptions().ObjC2)
+    Eng.registerCheck(new ObjCAtSyncChecker());
+}
+
+void ento::registerObjCAtSyncChecker(CheckerManager &mgr) {
+  mgr.addCheckerRegisterFunction(RegisterObjCAtSyncChecker);
+}
+
+void ObjCAtSyncChecker::PreVisitObjCAtSynchronizedStmt(CheckerContext &C,
+                                         const ObjCAtSynchronizedStmt *S) {
+
+  const Expr *Ex = S->getSynchExpr();
+  const GRState *state = C.getState();
+  SVal V = state->getSVal(Ex);
+
+  // Uninitialized value used for the mutex?
+  if (isa<UndefinedVal>(V)) {
+    if (ExplodedNode *N = C.generateSink()) {
+      if (!BT_undef)
+        BT_undef = new BuiltinBug("Uninitialized value used as mutex "
+                                  "for @synchronized");
+      EnhancedBugReport *report =
+        new EnhancedBugReport(*BT_undef, BT_undef->getDescription(), N);
+      report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, Ex);
+      C.EmitReport(report);
+    }
+    return;
+  }
+
+  if (V.isUnknown())
+    return;
+
+  // Check for null mutexes.
+  const GRState *notNullState, *nullState;
+  llvm::tie(notNullState, nullState) = state->assume(cast<DefinedSVal>(V));
+
+  if (nullState) {
+    if (!notNullState) {
+      // Generate an error node.  This isn't a sink since
+      // a null mutex just means no synchronization occurs.
+      if (ExplodedNode *N = C.generateNode(nullState)) {
+        if (!BT_null)
+          BT_null = new BuiltinBug("Nil value used as mutex for @synchronized() "
+                                   "(no synchronization will occur)");
+        EnhancedBugReport *report =
+          new EnhancedBugReport(*BT_null, BT_null->getDescription(), N);
+        report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
+                                  Ex);
+
+        C.EmitReport(report);
+        return;
+      }
+    }
+    // Don't add a transition for 'nullState'.  If the value is
+    // under-constrained to be null or non-null, assume it is non-null
+    // afterwards.
+  }
+
+  if (notNullState)
+    C.addTransition(notNullState);
+}
+