DirectIvarAssignment.cpp revision bf24792e00a47fd9d74ff21e21d2cbffc6d62818 
1//=- DirectIvarAssignment.cpp - Check rules on ObjC properties -*- 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//  Check that Objective C properties follow the following rules:
11//    - The property should be set with the setter, not though a direct
12//      assignment.
13//
14//===----------------------------------------------------------------------===//
15
16#include "ClangSACheckers.h"
17#include "clang/StaticAnalyzer/Core/Checker.h"
18#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
19#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
20#include "clang/AST/DeclObjC.h"
21#include "clang/AST/StmtVisitor.h"
22#include "llvm/ADT/DenseMap.h"
23
24using namespace clang;
25using namespace ento;
26
27namespace {
28
29class DirectIvarAssignment :
30  public Checker<check::ASTDecl<ObjCImplementationDecl> > {
31
32  typedef llvm::DenseMap<const ObjCIvarDecl*,
33                         const ObjCPropertyDecl*> IvarToPropertyMapTy;
34
35  /// A helper class, which walks the AST and locates all assignments to ivars
36  /// in the given function.
37  class MethodCrawler : public ConstStmtVisitor<MethodCrawler> {
38    const IvarToPropertyMapTy &IvarToPropMap;
39    const ObjCMethodDecl *MD;
40    const ObjCInterfaceDecl *InterfD;
41    BugReporter &BR;
42    LocationOrAnalysisDeclContext DCtx;
43
44  public:
45    MethodCrawler(const IvarToPropertyMapTy &InMap, const ObjCMethodDecl *InMD,
46        const ObjCInterfaceDecl *InID,
47        BugReporter &InBR, AnalysisDeclContext *InDCtx)
48    : IvarToPropMap(InMap), MD(InMD), InterfD(InID), BR(InBR), DCtx(InDCtx) {}
49
50    void VisitStmt(const Stmt *S) { VisitChildren(S); }
51
52    void VisitBinaryOperator(const BinaryOperator *BO);
53
54    void VisitChildren(const Stmt *S) {
55      for (Stmt::const_child_range I = S->children(); I; ++I)
56        if (*I)
57         this->Visit(*I);
58    }
59  };
60
61public:
62  void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& Mgr,
63                    BugReporter &BR) const;
64};
65
66static const ObjCIvarDecl *findPropertyBackingIvar(const ObjCPropertyDecl *PD,
67                                               const ObjCInterfaceDecl *InterD,
68                                               ASTContext &Ctx) {
69  // Check for synthesized ivars.
70  ObjCIvarDecl *ID = PD->getPropertyIvarDecl();
71  if (ID)
72    return ID;
73
74  ObjCInterfaceDecl *NonConstInterD = const_cast<ObjCInterfaceDecl*>(InterD);
75
76  // Check for existing "_PropName".
77  ID = NonConstInterD->lookupInstanceVariable(PD->getDefaultSynthIvarName(Ctx));
78  if (ID)
79    return ID;
80
81  // Check for existing "PropName".
82  IdentifierInfo *PropIdent = PD->getIdentifier();
83  ID = NonConstInterD->lookupInstanceVariable(PropIdent);
84
85  return ID;
86}
87
88void DirectIvarAssignment::checkASTDecl(const ObjCImplementationDecl *D,
89                                       AnalysisManager& Mgr,
90                                       BugReporter &BR) const {
91  const ObjCInterfaceDecl *InterD = D->getClassInterface();
92
93
94  IvarToPropertyMapTy IvarToPropMap;
95
96  // Find all properties for this class.
97  for (ObjCInterfaceDecl::prop_iterator I = InterD->prop_begin(),
98      E = InterD->prop_end(); I != E; ++I) {
99    ObjCPropertyDecl *PD = *I;
100
101    // Find the corresponding IVar.
102    const ObjCIvarDecl *ID = findPropertyBackingIvar(PD, InterD,
103                                                     Mgr.getASTContext());
104
105    if (!ID)
106      continue;
107
108    // Store the IVar to property mapping.
109    IvarToPropMap[ID] = PD;
110  }
111
112  if (IvarToPropMap.empty())
113    return;
114
115  for (ObjCImplementationDecl::instmeth_iterator I = D->instmeth_begin(),
116      E = D->instmeth_end(); I != E; ++I) {
117
118    ObjCMethodDecl *M = *I;
119    AnalysisDeclContext *DCtx = Mgr.getAnalysisDeclContext(M);
120
121    // Skip the init, dealloc functions and any functions that might be doing
122    // initialization based on their name.
123    if (M->getMethodFamily() == OMF_init ||
124        M->getMethodFamily() == OMF_dealloc ||
125        M->getSelector().getNameForSlot(0).find("init") != StringRef::npos ||
126        M->getSelector().getNameForSlot(0).find("Init") != StringRef::npos)
127      continue;
128
129    const Stmt *Body = M->getBody();
130    assert(Body);
131
132    MethodCrawler MC(IvarToPropMap, M->getCanonicalDecl(), InterD, BR, DCtx);
133    MC.VisitStmt(Body);
134  }
135}
136
137void DirectIvarAssignment::MethodCrawler::VisitBinaryOperator(
138                                                    const BinaryOperator *BO) {
139  if (!BO->isAssignmentOp())
140    return;
141
142  const ObjCIvarRefExpr *IvarRef =
143          dyn_cast<ObjCIvarRefExpr>(BO->getLHS()->IgnoreParenCasts());
144
145  if (!IvarRef)
146    return;
147
148  if (const ObjCIvarDecl *D = IvarRef->getDecl()) {
149    IvarToPropertyMapTy::const_iterator I = IvarToPropMap.find(D);
150    if (I != IvarToPropMap.end()) {
151      const ObjCPropertyDecl *PD = I->second;
152
153      ObjCMethodDecl *GetterMethod =
154          InterfD->getInstanceMethod(PD->getGetterName());
155      ObjCMethodDecl *SetterMethod =
156          InterfD->getInstanceMethod(PD->getSetterName());
157
158      if (SetterMethod && SetterMethod->getCanonicalDecl() == MD)
159        return;
160
161      if (GetterMethod && GetterMethod->getCanonicalDecl() == MD)
162        return;
163
164      BR.EmitBasicReport(MD,
165          "Property access",
166          categories::CoreFoundationObjectiveC,
167          "Direct assignment to an instance variable backing a property; "
168          "use the setter instead", PathDiagnosticLocation(IvarRef,
169                                                          BR.getSourceManager(),
170                                                          DCtx));
171    }
172  }
173}
174}
175
176void ento::registerDirectIvarAssignment(CheckerManager &mgr) {
177  mgr.registerChecker<DirectIvarAssignment>();
178}
179