| // BugReporterVisitors.cpp - Helpers for reporting bugs -----------*- 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 a set of BugReporter "visitors" which can be used to |
| // enhance the diagnostics reported for a bug. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/AST/Expr.h" |
| #include "clang/AST/ExprObjC.h" |
| #include "clang/GR/BugReporter/BugReporter.h" |
| #include "clang/GR/BugReporter/PathDiagnostic.h" |
| #include "clang/GR/PathSensitive/ExplodedGraph.h" |
| #include "clang/GR/PathSensitive/GRState.h" |
| |
| using namespace clang; |
| using namespace ento; |
| |
| //===----------------------------------------------------------------------===// |
| // Utility functions. |
| //===----------------------------------------------------------------------===// |
| |
| const Stmt *bugreporter::GetDerefExpr(const ExplodedNode *N) { |
| // Pattern match for a few useful cases (do something smarter later): |
| // a[0], p->f, *p |
| const Stmt *S = N->getLocationAs<PostStmt>()->getStmt(); |
| |
| if (const UnaryOperator *U = dyn_cast<UnaryOperator>(S)) { |
| if (U->getOpcode() == UO_Deref) |
| return U->getSubExpr()->IgnoreParenCasts(); |
| } |
| else if (const MemberExpr *ME = dyn_cast<MemberExpr>(S)) { |
| return ME->getBase()->IgnoreParenCasts(); |
| } |
| else if (const ArraySubscriptExpr *AE = dyn_cast<ArraySubscriptExpr>(S)) { |
| // Retrieve the base for arrays since BasicStoreManager doesn't know how |
| // to reason about them. |
| return AE->getBase(); |
| } |
| |
| return NULL; |
| } |
| |
| const Stmt *bugreporter::GetDenomExpr(const ExplodedNode *N) { |
| const Stmt *S = N->getLocationAs<PreStmt>()->getStmt(); |
| if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(S)) |
| return BE->getRHS(); |
| return NULL; |
| } |
| |
| const Stmt *bugreporter::GetCalleeExpr(const ExplodedNode *N) { |
| // Callee is checked as a PreVisit to the CallExpr. |
| const Stmt *S = N->getLocationAs<PreStmt>()->getStmt(); |
| if (const CallExpr *CE = dyn_cast<CallExpr>(S)) |
| return CE->getCallee(); |
| return NULL; |
| } |
| |
| const Stmt *bugreporter::GetRetValExpr(const ExplodedNode *N) { |
| const Stmt *S = N->getLocationAs<PostStmt>()->getStmt(); |
| if (const ReturnStmt *RS = dyn_cast<ReturnStmt>(S)) |
| return RS->getRetValue(); |
| return NULL; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Definitions for bug reporter visitors. |
| //===----------------------------------------------------------------------===// |
| |
| namespace { |
| class FindLastStoreBRVisitor : public BugReporterVisitor { |
| const MemRegion *R; |
| SVal V; |
| bool satisfied; |
| const ExplodedNode *StoreSite; |
| public: |
| FindLastStoreBRVisitor(SVal v, const MemRegion *r) |
| : R(r), V(v), satisfied(false), StoreSite(0) {} |
| |
| virtual void Profile(llvm::FoldingSetNodeID &ID) const { |
| static int tag = 0; |
| ID.AddPointer(&tag); |
| ID.AddPointer(R); |
| ID.Add(V); |
| } |
| |
| PathDiagnosticPiece* VisitNode(const ExplodedNode *N, |
| const ExplodedNode *PrevN, |
| BugReporterContext& BRC) { |
| |
| if (satisfied) |
| return NULL; |
| |
| if (!StoreSite) { |
| const ExplodedNode *Node = N, *Last = NULL; |
| |
| for ( ; Node ; Last = Node, Node = Node->getFirstPred()) { |
| |
| if (const VarRegion *VR = dyn_cast<VarRegion>(R)) { |
| if (const PostStmt *P = Node->getLocationAs<PostStmt>()) |
| if (const DeclStmt *DS = P->getStmtAs<DeclStmt>()) |
| if (DS->getSingleDecl() == VR->getDecl()) { |
| Last = Node; |
| break; |
| } |
| } |
| |
| if (Node->getState()->getSVal(R) != V) |
| break; |
| } |
| |
| if (!Node || !Last) { |
| satisfied = true; |
| return NULL; |
| } |
| |
| StoreSite = Last; |
| } |
| |
| if (StoreSite != N) |
| return NULL; |
| |
| satisfied = true; |
| llvm::SmallString<256> sbuf; |
| llvm::raw_svector_ostream os(sbuf); |
| |
| if (const PostStmt *PS = N->getLocationAs<PostStmt>()) { |
| if (const DeclStmt *DS = PS->getStmtAs<DeclStmt>()) { |
| |
| if (const VarRegion *VR = dyn_cast<VarRegion>(R)) { |
| os << "Variable '" << VR->getDecl() << "' "; |
| } |
| else |
| return NULL; |
| |
| if (isa<loc::ConcreteInt>(V)) { |
| bool b = false; |
| if (R->isBoundable()) { |
| if (const TypedRegion *TR = dyn_cast<TypedRegion>(R)) { |
| if (TR->getValueType()->isObjCObjectPointerType()) { |
| os << "initialized to nil"; |
| b = true; |
| } |
| } |
| } |
| |
| if (!b) |
| os << "initialized to a null pointer value"; |
| } |
| else if (isa<nonloc::ConcreteInt>(V)) { |
| os << "initialized to " << cast<nonloc::ConcreteInt>(V).getValue(); |
| } |
| else if (V.isUndef()) { |
| if (isa<VarRegion>(R)) { |
| const VarDecl *VD = cast<VarDecl>(DS->getSingleDecl()); |
| if (VD->getInit()) |
| os << "initialized to a garbage value"; |
| else |
| os << "declared without an initial value"; |
| } |
| } |
| } |
| } |
| |
| if (os.str().empty()) { |
| if (isa<loc::ConcreteInt>(V)) { |
| bool b = false; |
| if (R->isBoundable()) { |
| if (const TypedRegion *TR = dyn_cast<TypedRegion>(R)) { |
| if (TR->getValueType()->isObjCObjectPointerType()) { |
| os << "nil object reference stored to "; |
| b = true; |
| } |
| } |
| } |
| |
| if (!b) |
| os << "Null pointer value stored to "; |
| } |
| else if (V.isUndef()) { |
| os << "Uninitialized value stored to "; |
| } |
| else if (isa<nonloc::ConcreteInt>(V)) { |
| os << "The value " << cast<nonloc::ConcreteInt>(V).getValue() |
| << " is assigned to "; |
| } |
| else |
| return NULL; |
| |
| if (const VarRegion *VR = dyn_cast<VarRegion>(R)) { |
| os << '\'' << VR->getDecl() << '\''; |
| } |
| else |
| return NULL; |
| } |
| |
| // FIXME: Refactor this into BugReporterContext. |
| const Stmt *S = 0; |
| ProgramPoint P = N->getLocation(); |
| |
| if (BlockEdge *BE = dyn_cast<BlockEdge>(&P)) { |
| const CFGBlock *BSrc = BE->getSrc(); |
| S = BSrc->getTerminatorCondition(); |
| } |
| else if (PostStmt *PS = dyn_cast<PostStmt>(&P)) { |
| S = PS->getStmt(); |
| } |
| |
| if (!S) |
| return NULL; |
| |
| // Construct a new PathDiagnosticPiece. |
| PathDiagnosticLocation L(S, BRC.getSourceManager()); |
| return new PathDiagnosticEventPiece(L, os.str()); |
| } |
| }; |
| |
| |
| static void registerFindLastStore(BugReporterContext& BRC, const MemRegion *R, |
| SVal V) { |
| BRC.addVisitor(new FindLastStoreBRVisitor(V, R)); |
| } |
| |
| class TrackConstraintBRVisitor : public BugReporterVisitor { |
| DefinedSVal Constraint; |
| const bool Assumption; |
| bool isSatisfied; |
| public: |
| TrackConstraintBRVisitor(DefinedSVal constraint, bool assumption) |
| : Constraint(constraint), Assumption(assumption), isSatisfied(false) {} |
| |
| void Profile(llvm::FoldingSetNodeID &ID) const { |
| static int tag = 0; |
| ID.AddPointer(&tag); |
| ID.AddBoolean(Assumption); |
| ID.Add(Constraint); |
| } |
| |
| PathDiagnosticPiece* VisitNode(const ExplodedNode *N, |
| const ExplodedNode *PrevN, |
| BugReporterContext& BRC) { |
| if (isSatisfied) |
| return NULL; |
| |
| // Check if in the previous state it was feasible for this constraint |
| // to *not* be true. |
| if (PrevN->getState()->assume(Constraint, !Assumption)) { |
| |
| isSatisfied = true; |
| |
| // As a sanity check, make sure that the negation of the constraint |
| // was infeasible in the current state. If it is feasible, we somehow |
| // missed the transition point. |
| if (N->getState()->assume(Constraint, !Assumption)) |
| return NULL; |
| |
| // We found the transition point for the constraint. We now need to |
| // pretty-print the constraint. (work-in-progress) |
| std::string sbuf; |
| llvm::raw_string_ostream os(sbuf); |
| |
| if (isa<Loc>(Constraint)) { |
| os << "Assuming pointer value is "; |
| os << (Assumption ? "non-null" : "null"); |
| } |
| |
| if (os.str().empty()) |
| return NULL; |
| |
| // FIXME: Refactor this into BugReporterContext. |
| const Stmt *S = 0; |
| ProgramPoint P = N->getLocation(); |
| |
| if (BlockEdge *BE = dyn_cast<BlockEdge>(&P)) { |
| const CFGBlock *BSrc = BE->getSrc(); |
| S = BSrc->getTerminatorCondition(); |
| } |
| else if (PostStmt *PS = dyn_cast<PostStmt>(&P)) { |
| S = PS->getStmt(); |
| } |
| |
| if (!S) |
| return NULL; |
| |
| // Construct a new PathDiagnosticPiece. |
| PathDiagnosticLocation L(S, BRC.getSourceManager()); |
| return new PathDiagnosticEventPiece(L, os.str()); |
| } |
| |
| return NULL; |
| } |
| }; |
| } // end anonymous namespace |
| |
| static void registerTrackConstraint(BugReporterContext& BRC, |
| DefinedSVal Constraint, |
| bool Assumption) { |
| BRC.addVisitor(new TrackConstraintBRVisitor(Constraint, Assumption)); |
| } |
| |
| void bugreporter::registerTrackNullOrUndefValue(BugReporterContext& BRC, |
| const void *data, |
| const ExplodedNode* N) { |
| |
| const Stmt *S = static_cast<const Stmt*>(data); |
| |
| if (!S) |
| return; |
| |
| GRStateManager &StateMgr = BRC.getStateManager(); |
| const GRState *state = N->getState(); |
| |
| // Walk through lvalue-to-rvalue conversions. |
| if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(S)) { |
| if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { |
| const VarRegion *R = |
| StateMgr.getRegionManager().getVarRegion(VD, N->getLocationContext()); |
| |
| // What did we load? |
| SVal V = state->getSVal(loc::MemRegionVal(R)); |
| |
| if (isa<loc::ConcreteInt>(V) || isa<nonloc::ConcreteInt>(V) |
| || V.isUndef()) { |
| ::registerFindLastStore(BRC, R, V); |
| } |
| } |
| } |
| |
| SVal V = state->getSValAsScalarOrLoc(S); |
| |
| // Uncomment this to find cases where we aren't properly getting the |
| // base value that was dereferenced. |
| // assert(!V.isUnknownOrUndef()); |
| |
| // Is it a symbolic value? |
| if (loc::MemRegionVal *L = dyn_cast<loc::MemRegionVal>(&V)) { |
| const SubRegion *R = cast<SubRegion>(L->getRegion()); |
| while (R && !isa<SymbolicRegion>(R)) { |
| R = dyn_cast<SubRegion>(R->getSuperRegion()); |
| } |
| |
| if (R) { |
| assert(isa<SymbolicRegion>(R)); |
| registerTrackConstraint(BRC, loc::MemRegionVal(R), false); |
| } |
| } |
| } |
| |
| void bugreporter::registerFindLastStore(BugReporterContext& BRC, |
| const void *data, |
| const ExplodedNode* N) { |
| |
| const MemRegion *R = static_cast<const MemRegion*>(data); |
| |
| if (!R) |
| return; |
| |
| const GRState *state = N->getState(); |
| SVal V = state->getSVal(R); |
| |
| if (V.isUnknown()) |
| return; |
| |
| BRC.addVisitor(new FindLastStoreBRVisitor(V, R)); |
| } |
| |
| |
| namespace { |
| class NilReceiverVisitor : public BugReporterVisitor { |
| public: |
| NilReceiverVisitor() {} |
| |
| void Profile(llvm::FoldingSetNodeID &ID) const { |
| static int x = 0; |
| ID.AddPointer(&x); |
| } |
| |
| PathDiagnosticPiece* VisitNode(const ExplodedNode *N, |
| const ExplodedNode *PrevN, |
| BugReporterContext& BRC) { |
| |
| const PostStmt *P = N->getLocationAs<PostStmt>(); |
| if (!P) |
| return 0; |
| const ObjCMessageExpr *ME = P->getStmtAs<ObjCMessageExpr>(); |
| if (!ME) |
| return 0; |
| const Expr *Receiver = ME->getInstanceReceiver(); |
| if (!Receiver) |
| return 0; |
| const GRState *state = N->getState(); |
| const SVal &V = state->getSVal(Receiver); |
| const DefinedOrUnknownSVal *DV = dyn_cast<DefinedOrUnknownSVal>(&V); |
| if (!DV) |
| return 0; |
| state = state->assume(*DV, true); |
| if (state) |
| return 0; |
| |
| // The receiver was nil, and hence the method was skipped. |
| // Register a BugReporterVisitor to issue a message telling us how |
| // the receiver was null. |
| bugreporter::registerTrackNullOrUndefValue(BRC, Receiver, N); |
| // Issue a message saying that the method was skipped. |
| PathDiagnosticLocation L(Receiver, BRC.getSourceManager()); |
| return new PathDiagnosticEventPiece(L, "No method actually called " |
| "because the receiver is nil"); |
| } |
| }; |
| } // end anonymous namespace |
| |
| void bugreporter::registerNilReceiverVisitor(BugReporterContext &BRC) { |
| BRC.addVisitor(new NilReceiverVisitor()); |
| } |
| |
| // Registers every VarDecl inside a Stmt with a last store vistor. |
| void bugreporter::registerVarDeclsLastStore(BugReporterContext &BRC, |
| const void *stmt, |
| const ExplodedNode *N) { |
| const Stmt *S = static_cast<const Stmt *>(stmt); |
| |
| std::deque<const Stmt *> WorkList; |
| |
| WorkList.push_back(S); |
| |
| while (!WorkList.empty()) { |
| const Stmt *Head = WorkList.front(); |
| WorkList.pop_front(); |
| |
| GRStateManager &StateMgr = BRC.getStateManager(); |
| const GRState *state = N->getState(); |
| |
| if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Head)) { |
| if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { |
| const VarRegion *R = |
| StateMgr.getRegionManager().getVarRegion(VD, N->getLocationContext()); |
| |
| // What did we load? |
| SVal V = state->getSVal(S); |
| |
| if (isa<loc::ConcreteInt>(V) || isa<nonloc::ConcreteInt>(V)) { |
| ::registerFindLastStore(BRC, R, V); |
| } |
| } |
| } |
| |
| for (Stmt::const_child_iterator I = Head->child_begin(); |
| I != Head->child_end(); ++I) |
| WorkList.push_back(*I); |
| } |
| } |