1 //== ObjCSelfInitChecker.cpp - Checker for 'self' initialization -*- C++ -*--=//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This defines ObjCSelfInitChecker, a builtin check that checks for uses of
11 // 'self' before proper initialization.
13 //===----------------------------------------------------------------------===//
15 // This checks initialization methods to verify that they assign 'self' to the
16 // result of an initialization call (e.g. [super init], or [self initWith..])
17 // before using 'self' or any instance variable.
19 // To perform the required checking, values are tagged with flags that indicate
20 // 1) if the object is the one pointed to by 'self', and 2) if the object
21 // is the result of an initializer (e.g. [super init]).
23 // Uses of an object that is true for 1) but not 2) trigger a diagnostic.
24 // The uses that are currently checked are:
25 // - Using instance variables.
26 // - Returning the object.
28 // Note that we don't check for an invalid 'self' that is the receiver of an
29 // obj-c message expression to cut down false positives where logging functions
30 // get information from self (like its class) or doing "invalidation" on self
31 // when the initialization fails.
33 // Because the object that 'self' points to gets invalidated when a call
34 // receives a reference to 'self', the checker keeps track and passes the flags
35 // for 1) and 2) to the new object that 'self' points to after the call.
37 // FIXME (rdar://7937506): In the case of:
40 // Have an extra PathDiagnosticPiece in the path that says "called [super init],
41 // but didn't assign the result to self."
43 //===----------------------------------------------------------------------===//
45 // FIXME: Somehow stick the link to Apple's documentation about initializing
46 // objects in the diagnostics.
47 // http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ObjectiveC/Articles/ocAllocInit.html
49 #include "ClangSACheckers.h"
50 #include "clang/StaticAnalyzer/Core/Checker.h"
51 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
52 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
53 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
54 #include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h"
55 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
56 #include "clang/AST/ParentMap.h"
58 using namespace clang;
61 static bool shouldRunOnFunctionOrMethod(const NamedDecl *ND);
62 static bool isInitializationMethod(const ObjCMethodDecl *MD);
63 static bool isInitMessage(const ObjCMessage &msg);
64 static bool isSelfVar(SVal location, CheckerContext &C);
67 class ObjCSelfInitChecker : public Checker<
68 check::PostObjCMessage,
69 check::PostStmt<ObjCIvarRefExpr>,
70 check::PreStmt<ReturnStmt>,
71 check::PreStmt<CallExpr>,
72 check::PostStmt<CallExpr>,
75 void checkPostObjCMessage(ObjCMessage msg, CheckerContext &C) const;
76 void checkPostStmt(const ObjCIvarRefExpr *E, CheckerContext &C) const;
77 void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const;
78 void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
79 void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
80 void checkLocation(SVal location, bool isLoad, const Stmt *S,
81 CheckerContext &C) const;
83 } // end anonymous namespace
87 class InitSelfBug : public BugType {
88 const std::string desc;
90 InitSelfBug() : BugType("missing \"self = [(super or self) init...]\"",
91 "missing \"self = [(super or self) init...]\"") {}
94 } // end anonymous namespace
98 /// \brief No flag set.
100 /// \brief Value came from 'self'.
102 /// \brief Value came from the result of an initializer (e.g. [super init]).
103 SelfFlag_InitRes = 0x2
107 typedef llvm::ImmutableMap<SymbolRef, unsigned> SelfFlag;
108 namespace { struct CalledInit {}; }
109 namespace { struct PreCallSelfFlags {}; }
114 struct ProgramStateTrait<SelfFlag> : public ProgramStatePartialTrait<SelfFlag> {
115 static void *GDMIndex() { static int index = 0; return &index; }
118 struct ProgramStateTrait<CalledInit> : public ProgramStatePartialTrait<bool> {
119 static void *GDMIndex() { static int index = 0; return &index; }
122 /// \brief A call receiving a reference to 'self' invalidates the object that
123 /// 'self' contains. This keeps the "self flags" assigned to the 'self'
124 /// object before the call so we can assign them to the new object that 'self'
125 /// points to after the call.
127 struct ProgramStateTrait<PreCallSelfFlags> : public ProgramStatePartialTrait<unsigned> {
128 static void *GDMIndex() { static int index = 0; return &index; }
133 static SelfFlagEnum getSelfFlags(SVal val, const ProgramState *state) {
134 if (SymbolRef sym = val.getAsSymbol())
135 if (const unsigned *attachedFlags = state->get<SelfFlag>(sym))
136 return (SelfFlagEnum)*attachedFlags;
137 return SelfFlag_None;
140 static SelfFlagEnum getSelfFlags(SVal val, CheckerContext &C) {
141 return getSelfFlags(val, C.getState());
144 static void addSelfFlag(const ProgramState *state, SVal val,
145 SelfFlagEnum flag, CheckerContext &C) {
146 // We tag the symbol that the SVal wraps.
147 if (SymbolRef sym = val.getAsSymbol())
148 C.addTransition(state->set<SelfFlag>(sym, getSelfFlags(val, C) | flag));
151 static bool hasSelfFlag(SVal val, SelfFlagEnum flag, CheckerContext &C) {
152 return getSelfFlags(val, C) & flag;
155 /// \brief Returns true of the value of the expression is the object that 'self'
156 /// points to and is an object that did not come from the result of calling
158 static bool isInvalidSelf(const Expr *E, CheckerContext &C) {
159 SVal exprVal = C.getState()->getSVal(E);
160 if (!hasSelfFlag(exprVal, SelfFlag_Self, C))
161 return false; // value did not come from 'self'.
162 if (hasSelfFlag(exprVal, SelfFlag_InitRes, C))
163 return false; // 'self' is properly initialized.
168 static void checkForInvalidSelf(const Expr *E, CheckerContext &C,
169 const char *errorStr) {
173 if (!C.getState()->get<CalledInit>())
176 if (!isInvalidSelf(E, C))
179 // Generate an error node.
180 ExplodedNode *N = C.generateSink();
185 new BugReport(*new InitSelfBug(), errorStr, N);
186 C.EmitReport(report);
189 void ObjCSelfInitChecker::checkPostObjCMessage(ObjCMessage msg,
190 CheckerContext &C) const {
191 // When encountering a message that does initialization (init rule),
192 // tag the return value so that we know later on that if self has this value
193 // then it is properly initialized.
195 // FIXME: A callback should disable checkers at the start of functions.
196 if (!shouldRunOnFunctionOrMethod(dyn_cast<NamedDecl>(
197 C.getCurrentAnalysisContext()->getDecl())))
200 if (isInitMessage(msg)) {
201 // Tag the return value as the result of an initializer.
202 const ProgramState *state = C.getState();
204 // FIXME this really should be context sensitive, where we record
205 // the current stack frame (for IPA). Also, we need to clean this
206 // value out when we return from this method.
207 state = state->set<CalledInit>(true);
209 SVal V = state->getSVal(msg.getOriginExpr());
210 addSelfFlag(state, V, SelfFlag_InitRes, C);
214 // We don't check for an invalid 'self' in an obj-c message expression to cut
215 // down false positives where logging functions get information from self
216 // (like its class) or doing "invalidation" on self when the initialization
220 void ObjCSelfInitChecker::checkPostStmt(const ObjCIvarRefExpr *E,
221 CheckerContext &C) const {
222 // FIXME: A callback should disable checkers at the start of functions.
223 if (!shouldRunOnFunctionOrMethod(dyn_cast<NamedDecl>(
224 C.getCurrentAnalysisContext()->getDecl())))
227 checkForInvalidSelf(E->getBase(), C,
228 "Instance variable used while 'self' is not set to the result of "
229 "'[(super or self) init...]'");
232 void ObjCSelfInitChecker::checkPreStmt(const ReturnStmt *S,
233 CheckerContext &C) const {
234 // FIXME: A callback should disable checkers at the start of functions.
235 if (!shouldRunOnFunctionOrMethod(dyn_cast<NamedDecl>(
236 C.getCurrentAnalysisContext()->getDecl())))
239 checkForInvalidSelf(S->getRetValue(), C,
240 "Returning 'self' while it is not set to the result of "
241 "'[(super or self) init...]'");
244 // When a call receives a reference to 'self', [Pre/Post]VisitGenericCall pass
245 // the SelfFlags from the object 'self' point to before the call, to the new
246 // object after the call. This is to avoid invalidation of 'self' by logging
248 // Another common pattern in classes with multiple initializers is to put the
249 // subclass's common initialization bits into a static function that receives
250 // the value of 'self', e.g:
252 // if (!(self = [super init]))
254 // if (!(self = _commonInit(self)))
257 // Until we can use inter-procedural analysis, in such a call, transfer the
258 // SelfFlags to the result of the call.
260 void ObjCSelfInitChecker::checkPreStmt(const CallExpr *CE,
261 CheckerContext &C) const {
262 const ProgramState *state = C.getState();
263 for (CallExpr::const_arg_iterator
264 I = CE->arg_begin(), E = CE->arg_end(); I != E; ++I) {
265 SVal argV = state->getSVal(*I);
266 if (isSelfVar(argV, C)) {
267 unsigned selfFlags = getSelfFlags(state->getSVal(cast<Loc>(argV)), C);
268 C.addTransition(state->set<PreCallSelfFlags>(selfFlags));
270 } else if (hasSelfFlag(argV, SelfFlag_Self, C)) {
271 unsigned selfFlags = getSelfFlags(argV, C);
272 C.addTransition(state->set<PreCallSelfFlags>(selfFlags));
278 void ObjCSelfInitChecker::checkPostStmt(const CallExpr *CE,
279 CheckerContext &C) const {
280 const ProgramState *state = C.getState();
281 for (CallExpr::const_arg_iterator
282 I = CE->arg_begin(), E = CE->arg_end(); I != E; ++I) {
283 SVal argV = state->getSVal(*I);
284 if (isSelfVar(argV, C)) {
285 SelfFlagEnum prevFlags = (SelfFlagEnum)state->get<PreCallSelfFlags>();
286 state = state->remove<PreCallSelfFlags>();
287 addSelfFlag(state, state->getSVal(cast<Loc>(argV)), prevFlags, C);
289 } else if (hasSelfFlag(argV, SelfFlag_Self, C)) {
290 SelfFlagEnum prevFlags = (SelfFlagEnum)state->get<PreCallSelfFlags>();
291 state = state->remove<PreCallSelfFlags>();
292 addSelfFlag(state, state->getSVal(CE), prevFlags, C);
298 void ObjCSelfInitChecker::checkLocation(SVal location, bool isLoad,
300 CheckerContext &C) const {
301 // Tag the result of a load from 'self' so that we can easily know that the
302 // value is the object that 'self' points to.
303 const ProgramState *state = C.getState();
304 if (isSelfVar(location, C))
305 addSelfFlag(state, state->getSVal(cast<Loc>(location)), SelfFlag_Self, C);
308 // FIXME: A callback should disable checkers at the start of functions.
309 static bool shouldRunOnFunctionOrMethod(const NamedDecl *ND) {
313 const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(ND);
316 if (!isInitializationMethod(MD))
319 // self = [super init] applies only to NSObject subclasses.
320 // For instance, NSProxy doesn't implement -init.
321 ASTContext &Ctx = MD->getASTContext();
322 IdentifierInfo* NSObjectII = &Ctx.Idents.get("NSObject");
323 ObjCInterfaceDecl *ID = MD->getClassInterface()->getSuperClass();
324 for ( ; ID ; ID = ID->getSuperClass()) {
325 IdentifierInfo *II = ID->getIdentifier();
327 if (II == NSObjectII)
336 /// \brief Returns true if the location is 'self'.
337 static bool isSelfVar(SVal location, CheckerContext &C) {
338 AnalysisContext *analCtx = C.getCurrentAnalysisContext();
339 if (!analCtx->getSelfDecl())
341 if (!isa<loc::MemRegionVal>(location))
344 loc::MemRegionVal MRV = cast<loc::MemRegionVal>(location);
345 if (const DeclRegion *DR = dyn_cast<DeclRegion>(MRV.getRegion()))
346 return (DR->getDecl() == analCtx->getSelfDecl());
351 static bool isInitializationMethod(const ObjCMethodDecl *MD) {
352 return MD->getMethodFamily() == OMF_init;
355 static bool isInitMessage(const ObjCMessage &msg) {
356 return msg.getMethodFamily() == OMF_init;
359 //===----------------------------------------------------------------------===//
361 //===----------------------------------------------------------------------===//
363 void ento::registerObjCSelfInitChecker(CheckerManager &mgr) {
364 mgr.registerChecker<ObjCSelfInitChecker>();