1 //==- ObjCMissingSuperCallChecker.cpp - Check missing super-calls in ObjC --==//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines a ObjCMissingSuperCallChecker, a checker that
10 // analyzes a UIViewController implementation to determine if it
11 // correctly calls super in the methods where this is mandatory.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
16 #include "clang/Analysis/PathDiagnostic.h"
17 #include "clang/AST/DeclObjC.h"
18 #include "clang/AST/Expr.h"
19 #include "clang/AST/ExprObjC.h"
20 #include "clang/AST/RecursiveASTVisitor.h"
21 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
22 #include "clang/StaticAnalyzer/Core/Checker.h"
23 #include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
24 #include "llvm/ADT/SmallPtrSet.h"
25 #include "llvm/ADT/SmallString.h"
26 #include "llvm/Support/raw_ostream.h"
27
28 using namespace clang;
29 using namespace ento;
30
31 namespace {
32 struct SelectorDescriptor {
33 const char *SelectorName;
34 unsigned ArgumentCount;
35 };
36
37 //===----------------------------------------------------------------------===//
38 // FindSuperCallVisitor - Identify specific calls to the superclass.
39 //===----------------------------------------------------------------------===//
40
41 class FindSuperCallVisitor : public RecursiveASTVisitor<FindSuperCallVisitor> {
42 public:
FindSuperCallVisitor(Selector S)43 explicit FindSuperCallVisitor(Selector S) : DoesCallSuper(false), Sel(S) {}
44
VisitObjCMessageExpr(ObjCMessageExpr * E)45 bool VisitObjCMessageExpr(ObjCMessageExpr *E) {
46 if (E->getSelector() == Sel)
47 if (E->getReceiverKind() == ObjCMessageExpr::SuperInstance)
48 DoesCallSuper = true;
49
50 // Recurse if we didn't find the super call yet.
51 return !DoesCallSuper;
52 }
53
54 bool DoesCallSuper;
55
56 private:
57 Selector Sel;
58 };
59
60 //===----------------------------------------------------------------------===//
61 // ObjCSuperCallChecker
62 //===----------------------------------------------------------------------===//
63
64 class ObjCSuperCallChecker : public Checker<
65 check::ASTDecl<ObjCImplementationDecl> > {
66 public:
ObjCSuperCallChecker()67 ObjCSuperCallChecker() : IsInitialized(false) {}
68
69 void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager &Mgr,
70 BugReporter &BR) const;
71 private:
72 bool isCheckableClass(const ObjCImplementationDecl *D,
73 StringRef &SuperclassName) const;
74 void initializeSelectors(ASTContext &Ctx) const;
75 void fillSelectors(ASTContext &Ctx, ArrayRef<SelectorDescriptor> Sel,
76 StringRef ClassName) const;
77 mutable llvm::StringMap<llvm::SmallPtrSet<Selector, 16>> SelectorsForClass;
78 mutable bool IsInitialized;
79 };
80
81 }
82
83 /// Determine whether the given class has a superclass that we want
84 /// to check. The name of the found superclass is stored in SuperclassName.
85 ///
86 /// \param D The declaration to check for superclasses.
87 /// \param[out] SuperclassName On return, the found superclass name.
isCheckableClass(const ObjCImplementationDecl * D,StringRef & SuperclassName) const88 bool ObjCSuperCallChecker::isCheckableClass(const ObjCImplementationDecl *D,
89 StringRef &SuperclassName) const {
90 const ObjCInterfaceDecl *ID = D->getClassInterface()->getSuperClass();
91 for ( ; ID ; ID = ID->getSuperClass())
92 {
93 SuperclassName = ID->getIdentifier()->getName();
94 if (SelectorsForClass.count(SuperclassName))
95 return true;
96 }
97 return false;
98 }
99
fillSelectors(ASTContext & Ctx,ArrayRef<SelectorDescriptor> Sel,StringRef ClassName) const100 void ObjCSuperCallChecker::fillSelectors(ASTContext &Ctx,
101 ArrayRef<SelectorDescriptor> Sel,
102 StringRef ClassName) const {
103 llvm::SmallPtrSet<Selector, 16> &ClassSelectors =
104 SelectorsForClass[ClassName];
105 // Fill the Selectors SmallSet with all selectors we want to check.
106 for (ArrayRef<SelectorDescriptor>::iterator I = Sel.begin(), E = Sel.end();
107 I != E; ++I) {
108 SelectorDescriptor Descriptor = *I;
109 assert(Descriptor.ArgumentCount <= 1); // No multi-argument selectors yet.
110
111 // Get the selector.
112 IdentifierInfo *II = &Ctx.Idents.get(Descriptor.SelectorName);
113
114 Selector Sel = Ctx.Selectors.getSelector(Descriptor.ArgumentCount, &II);
115 ClassSelectors.insert(Sel);
116 }
117 }
118
initializeSelectors(ASTContext & Ctx) const119 void ObjCSuperCallChecker::initializeSelectors(ASTContext &Ctx) const {
120
121 { // Initialize selectors for: UIViewController
122 const SelectorDescriptor Selectors[] = {
123 { "addChildViewController", 1 },
124 { "viewDidAppear", 1 },
125 { "viewDidDisappear", 1 },
126 { "viewWillAppear", 1 },
127 { "viewWillDisappear", 1 },
128 { "removeFromParentViewController", 0 },
129 { "didReceiveMemoryWarning", 0 },
130 { "viewDidUnload", 0 },
131 { "viewDidLoad", 0 },
132 { "viewWillUnload", 0 },
133 { "updateViewConstraints", 0 },
134 { "encodeRestorableStateWithCoder", 1 },
135 { "restoreStateWithCoder", 1 }};
136
137 fillSelectors(Ctx, Selectors, "UIViewController");
138 }
139
140 { // Initialize selectors for: UIResponder
141 const SelectorDescriptor Selectors[] = {
142 { "resignFirstResponder", 0 }};
143
144 fillSelectors(Ctx, Selectors, "UIResponder");
145 }
146
147 { // Initialize selectors for: NSResponder
148 const SelectorDescriptor Selectors[] = {
149 { "encodeRestorableStateWithCoder", 1 },
150 { "restoreStateWithCoder", 1 }};
151
152 fillSelectors(Ctx, Selectors, "NSResponder");
153 }
154
155 { // Initialize selectors for: NSDocument
156 const SelectorDescriptor Selectors[] = {
157 { "encodeRestorableStateWithCoder", 1 },
158 { "restoreStateWithCoder", 1 }};
159
160 fillSelectors(Ctx, Selectors, "NSDocument");
161 }
162
163 IsInitialized = true;
164 }
165
checkASTDecl(const ObjCImplementationDecl * D,AnalysisManager & Mgr,BugReporter & BR) const166 void ObjCSuperCallChecker::checkASTDecl(const ObjCImplementationDecl *D,
167 AnalysisManager &Mgr,
168 BugReporter &BR) const {
169 ASTContext &Ctx = BR.getContext();
170
171 // We need to initialize the selector table once.
172 if (!IsInitialized)
173 initializeSelectors(Ctx);
174
175 // Find out whether this class has a superclass that we are supposed to check.
176 StringRef SuperclassName;
177 if (!isCheckableClass(D, SuperclassName))
178 return;
179
180
181 // Iterate over all instance methods.
182 for (auto *MD : D->instance_methods()) {
183 Selector S = MD->getSelector();
184 // Find out whether this is a selector that we want to check.
185 if (!SelectorsForClass[SuperclassName].count(S))
186 continue;
187
188 // Check if the method calls its superclass implementation.
189 if (MD->getBody())
190 {
191 FindSuperCallVisitor Visitor(S);
192 Visitor.TraverseDecl(MD);
193
194 // It doesn't call super, emit a diagnostic.
195 if (!Visitor.DoesCallSuper) {
196 PathDiagnosticLocation DLoc =
197 PathDiagnosticLocation::createEnd(MD->getBody(),
198 BR.getSourceManager(),
199 Mgr.getAnalysisDeclContext(D));
200
201 const char *Name = "Missing call to superclass";
202 SmallString<320> Buf;
203 llvm::raw_svector_ostream os(Buf);
204
205 os << "The '" << S.getAsString()
206 << "' instance method in " << SuperclassName.str() << " subclass '"
207 << *D << "' is missing a [super " << S.getAsString() << "] call";
208
209 BR.EmitBasicReport(MD, this, Name, categories::CoreFoundationObjectiveC,
210 os.str(), DLoc);
211 }
212 }
213 }
214 }
215
216
217 //===----------------------------------------------------------------------===//
218 // Check registration.
219 //===----------------------------------------------------------------------===//
220
registerObjCSuperCallChecker(CheckerManager & Mgr)221 void ento::registerObjCSuperCallChecker(CheckerManager &Mgr) {
222 Mgr.registerChecker<ObjCSuperCallChecker>();
223 }
224
shouldRegisterObjCSuperCallChecker(const CheckerManager & mgr)225 bool ento::shouldRegisterObjCSuperCallChecker(const CheckerManager &mgr) {
226 return true;
227 }
228
229 /*
230 ToDo list for expanding this check in the future, the list is not exhaustive.
231 There are also cases where calling super is suggested but not "mandatory".
232 In addition to be able to check the classes and methods below, architectural
233 improvements like being able to allow for the super-call to be done in a called
234 method would be good too.
235
236 UIDocument subclasses
237 - finishedHandlingError:recovered: (is multi-arg)
238 - finishedHandlingError:recovered: (is multi-arg)
239
240 UIViewController subclasses
241 - loadView (should *never* call super)
242 - transitionFromViewController:toViewController:
243 duration:options:animations:completion: (is multi-arg)
244
245 UICollectionViewController subclasses
246 - loadView (take care because UIViewController subclasses should NOT call super
247 in loadView, but UICollectionViewController subclasses should)
248
249 NSObject subclasses
250 - doesNotRecognizeSelector (it only has to call super if it doesn't throw)
251
252 UIPopoverBackgroundView subclasses (some of those are class methods)
253 - arrowDirection (should *never* call super)
254 - arrowOffset (should *never* call super)
255 - arrowBase (should *never* call super)
256 - arrowHeight (should *never* call super)
257 - contentViewInsets (should *never* call super)
258
259 UITextSelectionRect subclasses (some of those are properties)
260 - rect (should *never* call super)
261 - range (should *never* call super)
262 - writingDirection (should *never* call super)
263 - isVertical (should *never* call super)
264 - containsStart (should *never* call super)
265 - containsEnd (should *never* call super)
266 */
267