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//== 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 "GRExprEngineInternalChecks.h"
#include "clang/Checker/BugReporter/BugType.h"
#include "clang/Checker/Checkers/DereferenceChecker.h"
#include "clang/Checker/PathSensitive/CheckerVisitor.h"
#include "clang/Checker/PathSensitive/GRExprEngine.h"
using namespace clang;
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
void clang::RegisterObjCAtSyncChecker(GRExprEngine &Eng) {
Eng.registerCheck(new ObjCAtSyncChecker());
}
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;
}
// 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);
}
}
// From this point forward, we know that the mutex is null.
C.addTransition(nullState);
}
if (notNullState)
C.addTransition(notNullState);
}
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