clang  3.7.0
ExprEngineObjC.cpp
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1 //=-- ExprEngineObjC.cpp - ExprEngine support for Objective-C ---*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines ExprEngine's support for Objective-C expressions.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/AST/StmtObjC.h"
18 
19 using namespace clang;
20 using namespace ento;
21 
23  ExplodedNode *Pred,
24  ExplodedNodeSet &Dst) {
25  ProgramStateRef state = Pred->getState();
26  const LocationContext *LCtx = Pred->getLocationContext();
27  SVal baseVal = state->getSVal(Ex->getBase(), LCtx);
28  SVal location = state->getLValue(Ex->getDecl(), baseVal);
29 
30  ExplodedNodeSet dstIvar;
31  StmtNodeBuilder Bldr(Pred, dstIvar, *currBldrCtx);
32  Bldr.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, location));
33 
34  // Perform the post-condition check of the ObjCIvarRefExpr and store
35  // the created nodes in 'Dst'.
36  getCheckerManager().runCheckersForPostStmt(Dst, dstIvar, Ex, *this);
37 }
38 
40  ExplodedNode *Pred,
41  ExplodedNodeSet &Dst) {
42  getCheckerManager().runCheckersForPreStmt(Dst, Pred, S, *this);
43 }
44 
46  ExplodedNode *Pred,
47  ExplodedNodeSet &Dst) {
48 
49  // ObjCForCollectionStmts are processed in two places. This method
50  // handles the case where an ObjCForCollectionStmt* occurs as one of the
51  // statements within a basic block. This transfer function does two things:
52  //
53  // (1) binds the next container value to 'element'. This creates a new
54  // node in the ExplodedGraph.
55  //
56  // (2) binds the value 0/1 to the ObjCForCollectionStmt* itself, indicating
57  // whether or not the container has any more elements. This value
58  // will be tested in ProcessBranch. We need to explicitly bind
59  // this value because a container can contain nil elements.
60  //
61  // FIXME: Eventually this logic should actually do dispatches to
62  // 'countByEnumeratingWithState:objects:count:' (NSFastEnumeration).
63  // This will require simulating a temporary NSFastEnumerationState, either
64  // through an SVal or through the use of MemRegions. This value can
65  // be affixed to the ObjCForCollectionStmt* instead of 0/1; when the loop
66  // terminates we reclaim the temporary (it goes out of scope) and we
67  // we can test if the SVal is 0 or if the MemRegion is null (depending
68  // on what approach we take).
69  //
70  // For now: simulate (1) by assigning either a symbol or nil if the
71  // container is empty. Thus this transfer function will by default
72  // result in state splitting.
73 
74  const Stmt *elem = S->getElement();
75  ProgramStateRef state = Pred->getState();
76  SVal elementV;
77 
78  if (const DeclStmt *DS = dyn_cast<DeclStmt>(elem)) {
79  const VarDecl *elemD = cast<VarDecl>(DS->getSingleDecl());
80  assert(elemD->getInit() == nullptr);
81  elementV = state->getLValue(elemD, Pred->getLocationContext());
82  }
83  else {
84  elementV = state->getSVal(elem, Pred->getLocationContext());
85  }
86 
87  ExplodedNodeSet dstLocation;
88  evalLocation(dstLocation, S, elem, Pred, state, elementV, nullptr, false);
89 
90  ExplodedNodeSet Tmp;
91  StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx);
92 
93  for (ExplodedNodeSet::iterator NI = dstLocation.begin(),
94  NE = dstLocation.end(); NI!=NE; ++NI) {
95  Pred = *NI;
96  ProgramStateRef state = Pred->getState();
97  const LocationContext *LCtx = Pred->getLocationContext();
98 
99  // Handle the case where the container still has elements.
100  SVal TrueV = svalBuilder.makeTruthVal(1);
101  ProgramStateRef hasElems = state->BindExpr(S, LCtx, TrueV);
102 
103  // Handle the case where the container has no elements.
104  SVal FalseV = svalBuilder.makeTruthVal(0);
105  ProgramStateRef noElems = state->BindExpr(S, LCtx, FalseV);
106 
108  if (const TypedValueRegion *R =
109  dyn_cast<TypedValueRegion>(MV->getRegion())) {
110  // FIXME: The proper thing to do is to really iterate over the
111  // container. We will do this with dispatch logic to the store.
112  // For now, just 'conjure' up a symbolic value.
113  QualType T = R->getValueType();
114  assert(Loc::isLocType(T));
115  SymbolRef Sym = SymMgr.conjureSymbol(elem, LCtx, T,
116  currBldrCtx->blockCount());
117  SVal V = svalBuilder.makeLoc(Sym);
118  hasElems = hasElems->bindLoc(elementV, V);
119 
120  // Bind the location to 'nil' on the false branch.
121  SVal nilV = svalBuilder.makeIntVal(0, T);
122  noElems = noElems->bindLoc(elementV, nilV);
123  }
124 
125  // Create the new nodes.
126  Bldr.generateNode(S, Pred, hasElems);
127  Bldr.generateNode(S, Pred, noElems);
128  }
129 
130  // Finally, run any custom checkers.
131  // FIXME: Eventually all pre- and post-checks should live in VisitStmt.
132  getCheckerManager().runCheckersForPostStmt(Dst, Tmp, S, *this);
133 }
134 
136  ExplodedNode *Pred,
137  ExplodedNodeSet &Dst) {
140  CEMgr.getObjCMethodCall(ME, Pred->getState(), Pred->getLocationContext());
141 
142  // Handle the previsits checks.
143  ExplodedNodeSet dstPrevisit;
145  *Msg, *this);
146  ExplodedNodeSet dstGenericPrevisit;
147  getCheckerManager().runCheckersForPreCall(dstGenericPrevisit, dstPrevisit,
148  *Msg, *this);
149 
150  // Proceed with evaluate the message expression.
151  ExplodedNodeSet dstEval;
152  StmtNodeBuilder Bldr(dstGenericPrevisit, dstEval, *currBldrCtx);
153 
154  for (ExplodedNodeSet::iterator DI = dstGenericPrevisit.begin(),
155  DE = dstGenericPrevisit.end(); DI != DE; ++DI) {
156  ExplodedNode *Pred = *DI;
157  ProgramStateRef State = Pred->getState();
158  CallEventRef<ObjCMethodCall> UpdatedMsg = Msg.cloneWithState(State);
159 
160  if (UpdatedMsg->isInstanceMessage()) {
161  SVal recVal = UpdatedMsg->getReceiverSVal();
162  if (!recVal.isUndef()) {
163  // Bifurcate the state into nil and non-nil ones.
164  DefinedOrUnknownSVal receiverVal =
165  recVal.castAs<DefinedOrUnknownSVal>();
166 
167  ProgramStateRef notNilState, nilState;
168  std::tie(notNilState, nilState) = State->assume(receiverVal);
169 
170  // There are three cases: can be nil or non-nil, must be nil, must be
171  // non-nil. We ignore must be nil, and merge the rest two into non-nil.
172  // FIXME: This ignores many potential bugs (<rdar://problem/11733396>).
173  // Revisit once we have lazier constraints.
174  if (nilState && !notNilState) {
175  continue;
176  }
177 
178  // Check if the "raise" message was sent.
179  assert(notNilState);
180  if (ObjCNoRet.isImplicitNoReturn(ME)) {
181  // If we raise an exception, for now treat it as a sink.
182  // Eventually we will want to handle exceptions properly.
183  Bldr.generateSink(ME, Pred, State);
184  continue;
185  }
186 
187  // Generate a transition to non-Nil state.
188  if (notNilState != State) {
189  Pred = Bldr.generateNode(ME, Pred, notNilState);
190  assert(Pred && "Should have cached out already!");
191  }
192  }
193  } else {
194  // Check for special class methods that are known to not return
195  // and that we should treat as a sink.
196  if (ObjCNoRet.isImplicitNoReturn(ME)) {
197  // If we raise an exception, for now treat it as a sink.
198  // Eventually we will want to handle exceptions properly.
199  Bldr.generateSink(ME, Pred, Pred->getState());
200  continue;
201  }
202  }
203 
204  defaultEvalCall(Bldr, Pred, *UpdatedMsg);
205  }
206 
207  ExplodedNodeSet dstPostvisit;
208  getCheckerManager().runCheckersForPostCall(dstPostvisit, dstEval,
209  *Msg, *this);
210 
211  // Finally, perform the post-condition check of the ObjCMessageExpr and store
212  // the created nodes in 'Dst'.
214  *Msg, *this);
215 }
const Expr * getBase() const
Definition: ExprObjC.h:504
TypedValueRegion - An abstract class representing regions having a typed value.
Definition: MemRegion.h:498
nonloc::ConcreteInt makeIntVal(const IntegerLiteral *integer)
Definition: SValBuilder.h:232
This builder class is useful for generating nodes that resulted from visiting a statement. The main difference from its parent NodeBuilder is that it creates a statement specific ProgramPoint.
Definition: CoreEngine.h:345
Manages the lifetime of CallEvent objects.
Definition: CallEvent.h:897
const Expr * getInit() const
Definition: Decl.h:1068
Defines the Objective-C statement AST node classes.
Symbolic value. These values used to capture symbolic execution of the program.
Definition: SymbolManager.h:42
LineState State
void runCheckersForPostObjCMessage(ExplodedNodeSet &Dst, const ExplodedNodeSet &Src, const ObjCMethodCall &msg, ExprEngine &Eng, bool wasInlined=false)
Run checkers for post-visiting obj-c messages.
static bool isLocType(QualType T)
Definition: SVals.h:291
ExplodedNode * generateSink(const Stmt *S, ExplodedNode *Pred, ProgramStateRef St, const ProgramPointTag *tag=nullptr, ProgramPoint::Kind K=ProgramPoint::PostStmtKind)
Definition: CoreEngine.h:385
void runCheckersForPreCall(ExplodedNodeSet &Dst, const ExplodedNodeSet &Src, const CallEvent &Call, ExprEngine &Eng)
Run checkers for pre-visiting obj-c messages.
void runCheckersForPostCall(ExplodedNodeSet &Dst, const ExplodedNodeSet &Src, const CallEvent &Call, ExprEngine &Eng, bool wasInlined=false)
Run checkers for post-visiting obj-c messages.
ObjCIvarDecl * getDecl()
Definition: ExprObjC.h:500
const LocationContext * getLocationContext() const
unsigned blockCount() const
Returns the number of times the current basic block has been visited on the exploded graph path...
Definition: CoreEngine.h:191
CheckerManager & getCheckerManager() const
Definition: ExprEngine.h:127
Loc makeLoc(SymbolRef sym)
Definition: SValBuilder.h:300
void runCheckersForPostStmt(ExplodedNodeSet &Dst, const ExplodedNodeSet &Src, const Stmt *S, ExprEngine &Eng, bool wasInlined=false)
Run checkers for post-visiting Stmts.
const ProgramStateRef & getState() const
void VisitLvalObjCIvarRefExpr(const ObjCIvarRefExpr *DR, ExplodedNode *Pred, ExplodedNodeSet &Dst)
Transfer function logic for computing the lvalue of an Objective-C ivar.
void runCheckersForPreObjCMessage(ExplodedNodeSet &Dst, const ExplodedNodeSet &Src, const ObjCMethodCall &msg, ExprEngine &Eng)
Run checkers for pre-visiting obj-c messages.
Optional< T > getAs() const
Convert to the specified SVal type, returning None if this SVal is not of the desired type...
Definition: SVals.h:86
Represents Objective-C's @synchronized statement.
Definition: StmtObjC.h:262
An expression that sends a message to the given Objective-C object or class.
Definition: ExprObjC.h:858
CallEventRef< ObjCMethodCall > getObjCMethodCall(const ObjCMessageExpr *E, ProgramStateRef State, const LocationContext *LCtx)
Definition: CallEvent.h:960
CallEventManager & getCallEventManager()
Definition: ProgramState.h:507
void VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S, ExplodedNode *Pred, ExplodedNodeSet &Dst)
bool isUndef() const
Definition: SVals.h:121
void runCheckersForPreStmt(ExplodedNodeSet &Dst, const ExplodedNodeSet &Src, const Stmt *S, ExprEngine &Eng)
Run checkers for pre-visiting Stmts.
const SymbolConjured * conjureSymbol(const Stmt *E, const LocationContext *LCtx, QualType T, unsigned VisitCount, const void *SymbolTag=nullptr)
ProgramStateManager & getStateManager() override
Definition: ExprEngine.h:298
bool isImplicitNoReturn(const ObjCMessageExpr *ME)
Represents Objective-C's collection statement.
Definition: StmtObjC.h:24
void VisitObjCAtSynchronizedStmt(const ObjCAtSynchronizedStmt *S, ExplodedNode *Pred, ExplodedNodeSet &Dst)
Transfer function logic for ObjCAtSynchronizedStmts.
void VisitObjCMessage(const ObjCMessageExpr *ME, ExplodedNode *Pred, ExplodedNodeSet &Dst)
ObjCIvarRefExpr - A reference to an ObjC instance variable.
Definition: ExprObjC.h:474
void defaultEvalCall(NodeBuilder &B, ExplodedNode *Pred, const CallEvent &Call)
Default implementation of call evaluation.
CallEventRef< T > cloneWithState(ProgramStateRef State) const
Definition: CallEvent.h:58
ExplodedNode * generateNode(const Stmt *S, ExplodedNode *Pred, ProgramStateRef St, const ProgramPointTag *tag=nullptr, ProgramPoint::Kind K=ProgramPoint::PostStmtKind)
Definition: CoreEngine.h:375
nonloc::ConcreteInt makeTruthVal(bool b, QualType type)
Definition: SValBuilder.h:288
T castAs() const
Convert to the specified SVal type, asserting that this SVal is of the desired type.
Definition: SVals.h:75