clang  8.0.0svn
NSErrorChecker.cpp
Go to the documentation of this file.
1 //=- NSErrorChecker.cpp - Coding conventions for uses of NSError -*- 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 a CheckNSError, a flow-insenstive check
11 // that determines if an Objective-C class interface correctly returns
12 // a non-void return type.
13 //
14 // File under feature request PR 2600.
15 //
16 //===----------------------------------------------------------------------===//
17 
18 #include "ClangSACheckers.h"
19 #include "clang/AST/Decl.h"
20 #include "clang/AST/DeclObjC.h"
26 #include "llvm/ADT/SmallString.h"
27 #include "llvm/Support/raw_ostream.h"
28 
29 using namespace clang;
30 using namespace ento;
31 
32 static bool IsNSError(QualType T, IdentifierInfo *II);
33 static bool IsCFError(QualType T, IdentifierInfo *II);
34 
35 //===----------------------------------------------------------------------===//
36 // NSErrorMethodChecker
37 //===----------------------------------------------------------------------===//
38 
39 namespace {
40 class NSErrorMethodChecker
41  : public Checker< check::ASTDecl<ObjCMethodDecl> > {
42  mutable IdentifierInfo *II;
43 
44 public:
45  NSErrorMethodChecker() : II(nullptr) {}
46 
47  void checkASTDecl(const ObjCMethodDecl *D,
48  AnalysisManager &mgr, BugReporter &BR) const;
49 };
50 }
51 
52 void NSErrorMethodChecker::checkASTDecl(const ObjCMethodDecl *D,
53  AnalysisManager &mgr,
54  BugReporter &BR) const {
56  return;
57  if (!D->getReturnType()->isVoidType())
58  return;
59 
60  if (!II)
61  II = &D->getASTContext().Idents.get("NSError");
62 
63  bool hasNSError = false;
64  for (const auto *I : D->parameters()) {
65  if (IsNSError(I->getType(), II)) {
66  hasNSError = true;
67  break;
68  }
69  }
70 
71  if (hasNSError) {
72  const char *err = "Method accepting NSError** "
73  "should have a non-void return value to indicate whether or not an "
74  "error occurred";
75  PathDiagnosticLocation L =
76  PathDiagnosticLocation::create(D, BR.getSourceManager());
77  BR.EmitBasicReport(D, this, "Bad return type when passing NSError**",
78  "Coding conventions (Apple)", err, L);
79  }
80 }
81 
82 //===----------------------------------------------------------------------===//
83 // CFErrorFunctionChecker
84 //===----------------------------------------------------------------------===//
85 
86 namespace {
87 class CFErrorFunctionChecker
88  : public Checker< check::ASTDecl<FunctionDecl> > {
89  mutable IdentifierInfo *II;
90 
91 public:
92  CFErrorFunctionChecker() : II(nullptr) {}
93 
94  void checkASTDecl(const FunctionDecl *D,
95  AnalysisManager &mgr, BugReporter &BR) const;
96 };
97 }
98 
99 void CFErrorFunctionChecker::checkASTDecl(const FunctionDecl *D,
100  AnalysisManager &mgr,
101  BugReporter &BR) const {
103  return;
104  if (!D->getReturnType()->isVoidType())
105  return;
106 
107  if (!II)
108  II = &D->getASTContext().Idents.get("CFErrorRef");
109 
110  bool hasCFError = false;
111  for (auto I : D->parameters()) {
112  if (IsCFError(I->getType(), II)) {
113  hasCFError = true;
114  break;
115  }
116  }
117 
118  if (hasCFError) {
119  const char *err = "Function accepting CFErrorRef* "
120  "should have a non-void return value to indicate whether or not an "
121  "error occurred";
122  PathDiagnosticLocation L =
123  PathDiagnosticLocation::create(D, BR.getSourceManager());
124  BR.EmitBasicReport(D, this, "Bad return type when passing CFErrorRef*",
125  "Coding conventions (Apple)", err, L);
126  }
127 }
128 
129 //===----------------------------------------------------------------------===//
130 // NSOrCFErrorDerefChecker
131 //===----------------------------------------------------------------------===//
132 
133 namespace {
134 
135 class NSErrorDerefBug : public BugType {
136 public:
137  NSErrorDerefBug(const CheckerBase *Checker)
138  : BugType(Checker, "NSError** null dereference",
139  "Coding conventions (Apple)") {}
140 };
141 
142 class CFErrorDerefBug : public BugType {
143 public:
144  CFErrorDerefBug(const CheckerBase *Checker)
145  : BugType(Checker, "CFErrorRef* null dereference",
146  "Coding conventions (Apple)") {}
147 };
148 
149 }
150 
151 namespace {
152 class NSOrCFErrorDerefChecker
153  : public Checker< check::Location,
154  check::Event<ImplicitNullDerefEvent> > {
155  mutable IdentifierInfo *NSErrorII, *CFErrorII;
156  mutable std::unique_ptr<NSErrorDerefBug> NSBT;
157  mutable std::unique_ptr<CFErrorDerefBug> CFBT;
158 public:
159  bool ShouldCheckNSError, ShouldCheckCFError;
160  NSOrCFErrorDerefChecker() : NSErrorII(nullptr), CFErrorII(nullptr),
161  ShouldCheckNSError(0), ShouldCheckCFError(0) { }
162 
163  void checkLocation(SVal loc, bool isLoad, const Stmt *S,
164  CheckerContext &C) const;
165  void checkEvent(ImplicitNullDerefEvent event) const;
166 };
167 }
168 
169 typedef llvm::ImmutableMap<SymbolRef, unsigned> ErrorOutFlag;
170 REGISTER_TRAIT_WITH_PROGRAMSTATE(NSErrorOut, ErrorOutFlag)
171 REGISTER_TRAIT_WITH_PROGRAMSTATE(CFErrorOut, ErrorOutFlag)
172 
173 template <typename T>
174 static bool hasFlag(SVal val, ProgramStateRef state) {
175  if (SymbolRef sym = val.getAsSymbol())
176  if (const unsigned *attachedFlags = state->get<T>(sym))
177  return *attachedFlags;
178  return false;
179 }
180 
181 template <typename T>
182 static void setFlag(ProgramStateRef state, SVal val, CheckerContext &C) {
183  // We tag the symbol that the SVal wraps.
184  if (SymbolRef sym = val.getAsSymbol())
185  C.addTransition(state->set<T>(sym, true));
186 }
187 
188 static QualType parameterTypeFromSVal(SVal val, CheckerContext &C) {
189  const StackFrameContext * SFC = C.getStackFrame();
190  if (Optional<loc::MemRegionVal> X = val.getAs<loc::MemRegionVal>()) {
191  const MemRegion* R = X->getRegion();
192  if (const VarRegion *VR = R->getAs<VarRegion>())
193  if (const StackArgumentsSpaceRegion *
194  stackReg = dyn_cast<StackArgumentsSpaceRegion>(VR->getMemorySpace()))
195  if (stackReg->getStackFrame() == SFC)
196  return VR->getValueType();
197  }
198 
199  return QualType();
200 }
201 
202 void NSOrCFErrorDerefChecker::checkLocation(SVal loc, bool isLoad,
203  const Stmt *S,
204  CheckerContext &C) const {
205  if (!isLoad)
206  return;
207  if (loc.isUndef() || !loc.getAs<Loc>())
208  return;
209 
210  ASTContext &Ctx = C.getASTContext();
211  ProgramStateRef state = C.getState();
212 
213  // If we are loading from NSError**/CFErrorRef* parameter, mark the resulting
214  // SVal so that we can later check it when handling the
215  // ImplicitNullDerefEvent event.
216  // FIXME: Cumbersome! Maybe add hook at construction of SVals at start of
217  // function ?
218 
219  QualType parmT = parameterTypeFromSVal(loc, C);
220  if (parmT.isNull())
221  return;
222 
223  if (!NSErrorII)
224  NSErrorII = &Ctx.Idents.get("NSError");
225  if (!CFErrorII)
226  CFErrorII = &Ctx.Idents.get("CFErrorRef");
227 
228  if (ShouldCheckNSError && IsNSError(parmT, NSErrorII)) {
229  setFlag<NSErrorOut>(state, state->getSVal(loc.castAs<Loc>()), C);
230  return;
231  }
232 
233  if (ShouldCheckCFError && IsCFError(parmT, CFErrorII)) {
234  setFlag<CFErrorOut>(state, state->getSVal(loc.castAs<Loc>()), C);
235  return;
236  }
237 }
238 
239 void NSOrCFErrorDerefChecker::checkEvent(ImplicitNullDerefEvent event) const {
240  if (event.IsLoad)
241  return;
242 
243  SVal loc = event.Location;
244  ProgramStateRef state = event.SinkNode->getState();
245  BugReporter &BR = *event.BR;
246 
247  bool isNSError = hasFlag<NSErrorOut>(loc, state);
248  bool isCFError = false;
249  if (!isNSError)
250  isCFError = hasFlag<CFErrorOut>(loc, state);
251 
252  if (!(isNSError || isCFError))
253  return;
254 
255  // Storing to possible null NSError/CFErrorRef out parameter.
256  SmallString<128> Buf;
257  llvm::raw_svector_ostream os(Buf);
258 
259  os << "Potential null dereference. According to coding standards ";
260  os << (isNSError
261  ? "in 'Creating and Returning NSError Objects' the parameter"
262  : "documented in CoreFoundation/CFError.h the parameter");
263 
264  os << " may be null";
265 
266  BugType *bug = nullptr;
267  if (isNSError) {
268  if (!NSBT)
269  NSBT.reset(new NSErrorDerefBug(this));
270  bug = NSBT.get();
271  }
272  else {
273  if (!CFBT)
274  CFBT.reset(new CFErrorDerefBug(this));
275  bug = CFBT.get();
276  }
277  BR.emitReport(llvm::make_unique<BugReport>(*bug, os.str(), event.SinkNode));
278 }
279 
280 static bool IsNSError(QualType T, IdentifierInfo *II) {
281 
282  const PointerType* PPT = T->getAs<PointerType>();
283  if (!PPT)
284  return false;
285 
286  const ObjCObjectPointerType* PT =
288 
289  if (!PT)
290  return false;
291 
292  const ObjCInterfaceDecl *ID = PT->getInterfaceDecl();
293 
294  // FIXME: Can ID ever be NULL?
295  if (ID)
296  return II == ID->getIdentifier();
297 
298  return false;
299 }
300 
301 static bool IsCFError(QualType T, IdentifierInfo *II) {
302  const PointerType* PPT = T->getAs<PointerType>();
303  if (!PPT) return false;
304 
305  const TypedefType* TT = PPT->getPointeeType()->getAs<TypedefType>();
306  if (!TT) return false;
307 
308  return TT->getDecl()->getIdentifier() == II;
309 }
310 
311 void ento::registerNSErrorChecker(CheckerManager &mgr) {
312  mgr.registerChecker<NSErrorMethodChecker>();
313  NSOrCFErrorDerefChecker *checker =
314  mgr.registerChecker<NSOrCFErrorDerefChecker>();
315  checker->ShouldCheckNSError = true;
316 }
317 
318 void ento::registerCFErrorChecker(CheckerManager &mgr) {
319  mgr.registerChecker<CFErrorFunctionChecker>();
320  NSOrCFErrorDerefChecker *checker =
321  mgr.registerChecker<NSOrCFErrorDerefChecker>();
322  checker->ShouldCheckCFError = true;
323 }
Represents a function declaration or definition.
Definition: Decl.h:1732
bool isThisDeclarationADefinition() const
Returns whether this specific method is a definition.
Definition: DeclObjC.h:507
PointerType - C99 6.7.5.1 - Pointer Declarators.
Definition: Type.h:2543
QualType getPointeeType() const
Definition: Type.h:2556
A (possibly-)qualified type.
Definition: Type.h:642
const SymExpr * SymbolRef
Stmt - This represents one statement.
Definition: Stmt.h:66
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
static bool IsCFError(QualType T, IdentifierInfo *II)
QualType getReturnType() const
Definition: Decl.h:2290
const T * getAs() const
Member-template getAs<specific type>&#39;.
Definition: Type.h:6716
ObjCMethodDecl - Represents an instance or class method declaration.
Definition: DeclObjC.h:139
IdentifierInfo * getIdentifier() const
Get the identifier that names this declaration, if there is one.
Definition: Decl.h:269
One of these records is kept for each identifier that is lexed.
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:154
i32 captured_struct **param SharedsTy A type which contains references the shared variables *param Shareds Context with the list of shared variables from the p *TaskFunction *param Data Additional data for task generation like final * state
IdentifierTable & Idents
Definition: ASTContext.h:565
ArrayRef< ParmVarDecl * > parameters() const
Definition: Decl.h:2250
static PathDiagnosticLocation create(const Decl *D, const SourceManager &SM)
Create a location corresponding to the given declaration.
llvm::ImmutableMap< SymbolRef, unsigned > ErrorOutFlag
Represents an ObjC class declaration.
Definition: DeclObjC.h:1164
QualType getReturnType() const
Definition: DeclObjC.h:323
static void setFlag(ProgramStateRef state, SVal val, CheckerContext &C)
bool isNull() const
Return true if this QualType doesn&#39;t point to a type yet.
Definition: Type.h:707
#define REGISTER_TRAIT_WITH_PROGRAMSTATE(Name, Type)
Declares a program state trait for type Type called Name, and introduce a type named NameTy...
IdentifierInfo & get(StringRef Name)
Return the identifier token info for the specified named identifier.
ASTContext & getASTContext() const LLVM_READONLY
Definition: DeclBase.cpp:376
static bool hasFlag(SVal val, ProgramStateRef state)
Dataflow Directional Tag Classes.
Represents a pointer to an Objective C object.
Definition: Type.h:5780
ObjCInterfaceDecl * getInterfaceDecl() const
If this pointer points to an Objective @interface type, gets the declaration for that interface...
Definition: Type.h:5836
const StackFrameContext * getStackFrame() const
TypedefNameDecl * getDecl() const
Definition: Type.h:4153
X
Add a minimal nested name specifier fixit hint to allow lookup of a tag name from an outer enclosing ...
Definition: SemaDecl.cpp:13855
bool isVoidType() const
Definition: Type.h:6530
bool doesThisDeclarationHaveABody() const
Returns whether this specific declaration of the function has a body.
Definition: Decl.h:1983
static bool IsNSError(QualType T, IdentifierInfo *II)
static QualType parameterTypeFromSVal(SVal val, CheckerContext &C)
ArrayRef< ParmVarDecl * > parameters() const
Definition: DeclObjC.h:367