| //=-- ExprEngineObjC.cpp - ExprEngine support for Objective-C ---*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines ExprEngine's support for Objective-C expressions. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/AST/StmtObjC.h" |
| #include "clang/StaticAnalyzer/Core/CheckerManager.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" |
| #include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h" |
| |
| using namespace clang; |
| using namespace ento; |
| |
| void ExprEngine::VisitLvalObjCIvarRefExpr(const ObjCIvarRefExpr *Ex, |
| ExplodedNode *Pred, |
| ExplodedNodeSet &Dst) { |
| ProgramStateRef state = Pred->getState(); |
| const LocationContext *LCtx = Pred->getLocationContext(); |
| SVal baseVal = state->getSVal(Ex->getBase(), LCtx); |
| SVal location = state->getLValue(Ex->getDecl(), baseVal); |
| |
| ExplodedNodeSet dstIvar; |
| StmtNodeBuilder Bldr(Pred, dstIvar, *currentBuilderContext); |
| Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, location)); |
| |
| // Perform the post-condition check of the ObjCIvarRefExpr and store |
| // the created nodes in 'Dst'. |
| getCheckerManager().runCheckersForPostStmt(Dst, dstIvar, Ex, *this); |
| } |
| |
| void ExprEngine::VisitObjCAtSynchronizedStmt(const ObjCAtSynchronizedStmt *S, |
| ExplodedNode *Pred, |
| ExplodedNodeSet &Dst) { |
| getCheckerManager().runCheckersForPreStmt(Dst, Pred, S, *this); |
| } |
| |
| void ExprEngine::VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S, |
| ExplodedNode *Pred, |
| ExplodedNodeSet &Dst) { |
| |
| // ObjCForCollectionStmts are processed in two places. This method |
| // handles the case where an ObjCForCollectionStmt* occurs as one of the |
| // statements within a basic block. This transfer function does two things: |
| // |
| // (1) binds the next container value to 'element'. This creates a new |
| // node in the ExplodedGraph. |
| // |
| // (2) binds the value 0/1 to the ObjCForCollectionStmt* itself, indicating |
| // whether or not the container has any more elements. This value |
| // will be tested in ProcessBranch. We need to explicitly bind |
| // this value because a container can contain nil elements. |
| // |
| // FIXME: Eventually this logic should actually do dispatches to |
| // 'countByEnumeratingWithState:objects:count:' (NSFastEnumeration). |
| // This will require simulating a temporary NSFastEnumerationState, either |
| // through an SVal or through the use of MemRegions. This value can |
| // be affixed to the ObjCForCollectionStmt* instead of 0/1; when the loop |
| // terminates we reclaim the temporary (it goes out of scope) and we |
| // we can test if the SVal is 0 or if the MemRegion is null (depending |
| // on what approach we take). |
| // |
| // For now: simulate (1) by assigning either a symbol or nil if the |
| // container is empty. Thus this transfer function will by default |
| // result in state splitting. |
| |
| const Stmt *elem = S->getElement(); |
| ProgramStateRef state = Pred->getState(); |
| SVal elementV; |
| StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); |
| |
| if (const DeclStmt *DS = dyn_cast<DeclStmt>(elem)) { |
| const VarDecl *elemD = cast<VarDecl>(DS->getSingleDecl()); |
| assert(elemD->getInit() == 0); |
| elementV = state->getLValue(elemD, Pred->getLocationContext()); |
| } |
| else { |
| elementV = state->getSVal(elem, Pred->getLocationContext()); |
| } |
| |
| ExplodedNodeSet dstLocation; |
| Bldr.takeNodes(Pred); |
| evalLocation(dstLocation, elem, Pred, state, elementV, NULL, false); |
| Bldr.addNodes(dstLocation); |
| |
| for (ExplodedNodeSet::iterator NI = dstLocation.begin(), |
| NE = dstLocation.end(); NI!=NE; ++NI) { |
| Pred = *NI; |
| ProgramStateRef state = Pred->getState(); |
| const LocationContext *LCtx = Pred->getLocationContext(); |
| |
| // Handle the case where the container still has elements. |
| SVal TrueV = svalBuilder.makeTruthVal(1); |
| ProgramStateRef hasElems = state->BindExpr(S, LCtx, TrueV); |
| |
| // Handle the case where the container has no elements. |
| SVal FalseV = svalBuilder.makeTruthVal(0); |
| ProgramStateRef noElems = state->BindExpr(S, LCtx, FalseV); |
| |
| if (loc::MemRegionVal *MV = dyn_cast<loc::MemRegionVal>(&elementV)) |
| if (const TypedValueRegion *R = |
| dyn_cast<TypedValueRegion>(MV->getRegion())) { |
| // FIXME: The proper thing to do is to really iterate over the |
| // container. We will do this with dispatch logic to the store. |
| // For now, just 'conjure' up a symbolic value. |
| QualType T = R->getValueType(); |
| assert(Loc::isLocType(T)); |
| unsigned Count = currentBuilderContext->getCurrentBlockCount(); |
| SymbolRef Sym = SymMgr.getConjuredSymbol(elem, LCtx, T, Count); |
| SVal V = svalBuilder.makeLoc(Sym); |
| hasElems = hasElems->bindLoc(elementV, V); |
| |
| // Bind the location to 'nil' on the false branch. |
| SVal nilV = svalBuilder.makeIntVal(0, T); |
| noElems = noElems->bindLoc(elementV, nilV); |
| } |
| |
| // Create the new nodes. |
| Bldr.generateNode(S, Pred, hasElems); |
| Bldr.generateNode(S, Pred, noElems); |
| } |
| } |
| |
| void ExprEngine::VisitObjCMessage(const ObjCMessage &msg, |
| ExplodedNode *Pred, |
| ExplodedNodeSet &Dst) { |
| |
| // Handle the previsits checks. |
| ExplodedNodeSet dstPrevisit; |
| getCheckerManager().runCheckersForPreObjCMessage(dstPrevisit, Pred, |
| msg, *this); |
| |
| // Proceed with evaluate the message expression. |
| ExplodedNodeSet dstEval; |
| StmtNodeBuilder Bldr(dstPrevisit, dstEval, *currentBuilderContext); |
| |
| for (ExplodedNodeSet::iterator DI = dstPrevisit.begin(), |
| DE = dstPrevisit.end(); DI != DE; ++DI) { |
| |
| ExplodedNode *Pred = *DI; |
| bool RaisesException = false; |
| |
| if (const Expr *Receiver = msg.getInstanceReceiver()) { |
| ProgramStateRef state = Pred->getState(); |
| SVal recVal = state->getSVal(Receiver, Pred->getLocationContext()); |
| if (!recVal.isUndef()) { |
| // Bifurcate the state into nil and non-nil ones. |
| DefinedOrUnknownSVal receiverVal = cast<DefinedOrUnknownSVal>(recVal); |
| |
| ProgramStateRef notNilState, nilState; |
| llvm::tie(notNilState, nilState) = state->assume(receiverVal); |
| |
| // There are three cases: can be nil or non-nil, must be nil, must be |
| // non-nil. We ignore must be nil, and merge the rest two into non-nil. |
| if (nilState && !notNilState) { |
| continue; |
| } |
| |
| // Check if the "raise" message was sent. |
| assert(notNilState); |
| if (msg.getSelector() == RaiseSel) |
| RaisesException = true; |
| |
| // If we raise an exception, for now treat it as a sink. |
| // Eventually we will want to handle exceptions properly. |
| // Dispatch to plug-in transfer function. |
| evalObjCMessage(Bldr, msg, Pred, notNilState, RaisesException); |
| } |
| } |
| else if (const ObjCInterfaceDecl *Iface = msg.getReceiverInterface()) { |
| IdentifierInfo* ClsName = Iface->getIdentifier(); |
| Selector S = msg.getSelector(); |
| |
| // Check for special instance methods. |
| if (!NSExceptionII) { |
| ASTContext &Ctx = getContext(); |
| NSExceptionII = &Ctx.Idents.get("NSException"); |
| } |
| |
| if (ClsName == NSExceptionII) { |
| enum { NUM_RAISE_SELECTORS = 2 }; |
| |
| // Lazily create a cache of the selectors. |
| if (!NSExceptionInstanceRaiseSelectors) { |
| ASTContext &Ctx = getContext(); |
| NSExceptionInstanceRaiseSelectors = |
| new Selector[NUM_RAISE_SELECTORS]; |
| SmallVector<IdentifierInfo*, NUM_RAISE_SELECTORS> II; |
| unsigned idx = 0; |
| |
| // raise:format: |
| II.push_back(&Ctx.Idents.get("raise")); |
| II.push_back(&Ctx.Idents.get("format")); |
| NSExceptionInstanceRaiseSelectors[idx++] = |
| Ctx.Selectors.getSelector(II.size(), &II[0]); |
| |
| // raise:format::arguments: |
| II.push_back(&Ctx.Idents.get("arguments")); |
| NSExceptionInstanceRaiseSelectors[idx++] = |
| Ctx.Selectors.getSelector(II.size(), &II[0]); |
| } |
| |
| for (unsigned i = 0; i < NUM_RAISE_SELECTORS; ++i) |
| if (S == NSExceptionInstanceRaiseSelectors[i]) { |
| RaisesException = true; |
| break; |
| } |
| } |
| |
| // If we raise an exception, for now treat it as a sink. |
| // Eventually we will want to handle exceptions properly. |
| // Dispatch to plug-in transfer function. |
| evalObjCMessage(Bldr, msg, Pred, Pred->getState(), RaisesException); |
| } |
| } |
| |
| // Finally, perform the post-condition check of the ObjCMessageExpr and store |
| // the created nodes in 'Dst'. |
| getCheckerManager().runCheckersForPostObjCMessage(Dst, dstEval, msg, *this); |
| } |
| |
| void ExprEngine::evalObjCMessage(StmtNodeBuilder &Bldr, |
| const ObjCMessage &msg, |
| ExplodedNode *Pred, |
| ProgramStateRef state, |
| bool GenSink) { |
| // First handle the return value. |
| SVal ReturnValue = UnknownVal(); |
| |
| // Some method families have known return values. |
| switch (msg.getMethodFamily()) { |
| default: |
| break; |
| case OMF_autorelease: |
| case OMF_retain: |
| case OMF_self: { |
| // These methods return their receivers. |
| const Expr *ReceiverE = msg.getInstanceReceiver(); |
| if (ReceiverE) |
| ReturnValue = state->getSVal(ReceiverE, Pred->getLocationContext()); |
| break; |
| } |
| } |
| |
| // If we failed to figure out the return value, use a conjured value instead. |
| if (ReturnValue.isUnknown()) { |
| SValBuilder &SVB = getSValBuilder(); |
| QualType ResultTy = msg.getResultType(getContext()); |
| unsigned Count = currentBuilderContext->getCurrentBlockCount(); |
| const Expr *CurrentE = cast<Expr>(currentStmt); |
| const LocationContext *LCtx = Pred->getLocationContext(); |
| ReturnValue = SVB.getConjuredSymbolVal(NULL, CurrentE, LCtx, ResultTy, Count); |
| } |
| |
| // Bind the return value. |
| const LocationContext *LCtx = Pred->getLocationContext(); |
| state = state->BindExpr(currentStmt, LCtx, ReturnValue); |
| |
| // Invalidate the arguments (and the receiver) |
| state = invalidateArguments(state, CallOrObjCMessage(msg, state, LCtx), LCtx); |
| |
| // And create the new node. |
| Bldr.generateNode(msg.getMessageExpr(), Pred, state, GenSink); |
| assert(Bldr.hasGeneratedNodes()); |
| } |
| |