//== RetainSummaryManager.cpp - Summaries for reference counting --*- C++ -*--// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This file defines summaries implementation for retain counting, which // implements a reference count checker for Core Foundation, Cocoa // and OSObject (on Mac OS X). // //===----------------------------------------------------------------------===// #include "clang/Analysis/DomainSpecific/CocoaConventions.h" #include "clang/Analysis/RetainSummaryManager.h" #include "clang/AST/Attr.h" #include "clang/AST/DeclCXX.h" #include "clang/AST/DeclObjC.h" #include "clang/AST/ParentMap.h" #include "clang/ASTMatchers/ASTMatchFinder.h" using namespace clang; using namespace ento; template constexpr static bool isOneOf() { return false; } /// Helper function to check whether the class is one of the /// rest of varargs. template constexpr static bool isOneOf() { return std::is_same::value || isOneOf(); } namespace { /// Fake attribute class for RC* attributes. struct GeneralizedReturnsRetainedAttr { static bool classof(const Attr *A) { if (auto AA = dyn_cast(A)) return AA->getAnnotation() == "rc_ownership_returns_retained"; return false; } }; struct GeneralizedReturnsNotRetainedAttr { static bool classof(const Attr *A) { if (auto AA = dyn_cast(A)) return AA->getAnnotation() == "rc_ownership_returns_not_retained"; return false; } }; struct GeneralizedConsumedAttr { static bool classof(const Attr *A) { if (auto AA = dyn_cast(A)) return AA->getAnnotation() == "rc_ownership_consumed"; return false; } }; } template Optional RetainSummaryManager::hasAnyEnabledAttrOf(const Decl *D, QualType QT) { ObjKind K; if (isOneOf()) { if (!TrackObjCAndCFObjects) return None; K = ObjKind::CF; } else if (isOneOf()) { if (!TrackObjCAndCFObjects) return None; if (isOneOf() && !cocoa::isCocoaObjectRef(QT)) return None; K = ObjKind::ObjC; } else if (isOneOf()) { if (!TrackOSObjects) return None; K = ObjKind::OS; } else if (isOneOf()) { K = ObjKind::Generalized; } else { llvm_unreachable("Unexpected attribute"); } if (D->hasAttr()) return K; return None; } template Optional RetainSummaryManager::hasAnyEnabledAttrOf(const Decl *D, QualType QT) { if (auto Out = hasAnyEnabledAttrOf(D, QT)) return Out; return hasAnyEnabledAttrOf(D, QT); } const RetainSummary * RetainSummaryManager::getPersistentSummary(const RetainSummary &OldSumm) { // Unique "simple" summaries -- those without ArgEffects. if (OldSumm.isSimple()) { ::llvm::FoldingSetNodeID ID; OldSumm.Profile(ID); void *Pos; CachedSummaryNode *N = SimpleSummaries.FindNodeOrInsertPos(ID, Pos); if (!N) { N = (CachedSummaryNode *) BPAlloc.Allocate(); new (N) CachedSummaryNode(OldSumm); SimpleSummaries.InsertNode(N, Pos); } return &N->getValue(); } RetainSummary *Summ = (RetainSummary *) BPAlloc.Allocate(); new (Summ) RetainSummary(OldSumm); return Summ; } static bool isSubclass(const Decl *D, StringRef ClassName) { using namespace ast_matchers; DeclarationMatcher SubclassM = cxxRecordDecl(isSameOrDerivedFrom(std::string(ClassName))); return !(match(SubclassM, *D, D->getASTContext()).empty()); } static bool isExactClass(const Decl *D, StringRef ClassName) { using namespace ast_matchers; DeclarationMatcher sameClassM = cxxRecordDecl(hasName(std::string(ClassName))); return !(match(sameClassM, *D, D->getASTContext()).empty()); } static bool isOSObjectSubclass(const Decl *D) { return D && isSubclass(D, "OSMetaClassBase") && !isExactClass(D, "OSMetaClass"); } static bool isOSObjectDynamicCast(StringRef S) { return S == "safeMetaCast"; } static bool isOSObjectRequiredCast(StringRef S) { return S == "requiredMetaCast"; } static bool isOSObjectThisCast(StringRef S) { return S == "metaCast"; } static bool isOSObjectPtr(QualType QT) { return isOSObjectSubclass(QT->getPointeeCXXRecordDecl()); } static bool isISLObjectRef(QualType Ty) { return StringRef(Ty.getAsString()).startswith("isl_"); } static bool isOSIteratorSubclass(const Decl *D) { return isSubclass(D, "OSIterator"); } static bool hasRCAnnotation(const Decl *D, StringRef rcAnnotation) { for (const auto *Ann : D->specific_attrs()) { if (Ann->getAnnotation() == rcAnnotation) return true; } return false; } static bool isRetain(const FunctionDecl *FD, StringRef FName) { return FName.startswith_insensitive("retain") || FName.endswith_insensitive("retain"); } static bool isRelease(const FunctionDecl *FD, StringRef FName) { return FName.startswith_insensitive("release") || FName.endswith_insensitive("release"); } static bool isAutorelease(const FunctionDecl *FD, StringRef FName) { return FName.startswith_insensitive("autorelease") || FName.endswith_insensitive("autorelease"); } static bool isMakeCollectable(StringRef FName) { return FName.contains_insensitive("MakeCollectable"); } /// A function is OSObject related if it is declared on a subclass /// of OSObject, or any of the parameters is a subclass of an OSObject. static bool isOSObjectRelated(const CXXMethodDecl *MD) { if (isOSObjectSubclass(MD->getParent())) return true; for (ParmVarDecl *Param : MD->parameters()) { QualType PT = Param->getType()->getPointeeType(); if (!PT.isNull()) if (CXXRecordDecl *RD = PT->getAsCXXRecordDecl()) if (isOSObjectSubclass(RD)) return true; } return false; } bool RetainSummaryManager::isKnownSmartPointer(QualType QT) { QT = QT.getCanonicalType(); const auto *RD = QT->getAsCXXRecordDecl(); if (!RD) return false; const IdentifierInfo *II = RD->getIdentifier(); if (II && II->getName() == "smart_ptr") if (const auto *ND = dyn_cast(RD->getDeclContext())) if (ND->getNameAsString() == "os") return true; return false; } const RetainSummary * RetainSummaryManager::getSummaryForOSObject(const FunctionDecl *FD, StringRef FName, QualType RetTy) { assert(TrackOSObjects && "Requesting a summary for an OSObject but OSObjects are not tracked"); if (RetTy->isPointerType()) { const CXXRecordDecl *PD = RetTy->getPointeeType()->getAsCXXRecordDecl(); if (PD && isOSObjectSubclass(PD)) { if (isOSObjectDynamicCast(FName) || isOSObjectRequiredCast(FName) || isOSObjectThisCast(FName)) return getDefaultSummary(); // TODO: Add support for the slightly common *Matching(table) idiom. // Cf. IOService::nameMatching() etc. - these function have an unusual // contract of returning at +0 or +1 depending on their last argument. if (FName.endswith("Matching")) { return getPersistentStopSummary(); } // All objects returned with functions *not* starting with 'get', // or iterators, are returned at +1. if ((!FName.startswith("get") && !FName.startswith("Get")) || isOSIteratorSubclass(PD)) { return getOSSummaryCreateRule(FD); } else { return getOSSummaryGetRule(FD); } } } if (const auto *MD = dyn_cast(FD)) { const CXXRecordDecl *Parent = MD->getParent(); if (Parent && isOSObjectSubclass(Parent)) { if (FName == "release" || FName == "taggedRelease") return getOSSummaryReleaseRule(FD); if (FName == "retain" || FName == "taggedRetain") return getOSSummaryRetainRule(FD); if (FName == "free") return getOSSummaryFreeRule(FD); if (MD->getOverloadedOperator() == OO_New) return getOSSummaryCreateRule(MD); } } return nullptr; } const RetainSummary *RetainSummaryManager::getSummaryForObjCOrCFObject( const FunctionDecl *FD, StringRef FName, QualType RetTy, const FunctionType *FT, bool &AllowAnnotations) { ArgEffects ScratchArgs(AF.getEmptyMap()); std::string RetTyName = RetTy.getAsString(); if (FName == "pthread_create" || FName == "pthread_setspecific") { // Part of: and . // This will be addressed better with IPA. return getPersistentStopSummary(); } else if(FName == "NSMakeCollectable") { // Handle: id NSMakeCollectable(CFTypeRef) AllowAnnotations = false; return RetTy->isObjCIdType() ? getUnarySummary(FT, DoNothing) : getPersistentStopSummary(); } else if (FName == "CMBufferQueueDequeueAndRetain" || FName == "CMBufferQueueDequeueIfDataReadyAndRetain") { // Part of: . return getPersistentSummary(RetEffect::MakeOwned(ObjKind::CF), ScratchArgs, ArgEffect(DoNothing), ArgEffect(DoNothing)); } else if (FName == "CFPlugInInstanceCreate") { return getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs); } else if (FName == "IORegistryEntrySearchCFProperty" || (RetTyName == "CFMutableDictionaryRef" && (FName == "IOBSDNameMatching" || FName == "IOServiceMatching" || FName == "IOServiceNameMatching" || FName == "IORegistryEntryIDMatching" || FName == "IOOpenFirmwarePathMatching"))) { // Part of . (IOKit) // This should be addressed using a API table. return getPersistentSummary(RetEffect::MakeOwned(ObjKind::CF), ScratchArgs, ArgEffect(DoNothing), ArgEffect(DoNothing)); } else if (FName == "IOServiceGetMatchingService" || FName == "IOServiceGetMatchingServices") { // FIXES: // This should be addressed using a API table. This strcmp is also // a little gross, but there is no need to super optimize here. ScratchArgs = AF.add(ScratchArgs, 1, ArgEffect(DecRef, ObjKind::CF)); return getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs, ArgEffect(DoNothing), ArgEffect(DoNothing)); } else if (FName == "IOServiceAddNotification" || FName == "IOServiceAddMatchingNotification") { // Part of . (IOKit) // This should be addressed using a API table. ScratchArgs = AF.add(ScratchArgs, 2, ArgEffect(DecRef, ObjKind::CF)); return getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs, ArgEffect(DoNothing), ArgEffect(DoNothing)); } else if (FName == "CVPixelBufferCreateWithBytes") { // FIXES: // Eventually this can be improved by recognizing that the pixel // buffer passed to CVPixelBufferCreateWithBytes is released via // a callback and doing full IPA to make sure this is done correctly. // FIXME: This function has an out parameter that returns an // allocated object. ScratchArgs = AF.add(ScratchArgs, 7, ArgEffect(StopTracking)); return getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs, ArgEffect(DoNothing), ArgEffect(DoNothing)); } else if (FName == "CGBitmapContextCreateWithData") { // FIXES: // Eventually this can be improved by recognizing that 'releaseInfo' // passed to CGBitmapContextCreateWithData is released via // a callback and doing full IPA to make sure this is done correctly. ScratchArgs = AF.add(ScratchArgs, 8, ArgEffect(ArgEffect(StopTracking))); return getPersistentSummary(RetEffect::MakeOwned(ObjKind::CF), ScratchArgs, ArgEffect(DoNothing), ArgEffect(DoNothing)); } else if (FName == "CVPixelBufferCreateWithPlanarBytes") { // FIXES: // Eventually this can be improved by recognizing that the pixel // buffer passed to CVPixelBufferCreateWithPlanarBytes is released // via a callback and doing full IPA to make sure this is done // correctly. ScratchArgs = AF.add(ScratchArgs, 12, ArgEffect(StopTracking)); return getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs, ArgEffect(DoNothing), ArgEffect(DoNothing)); } else if (FName == "VTCompressionSessionEncodeFrame") { // The context argument passed to VTCompressionSessionEncodeFrame() // is passed to the callback specified when creating the session // (e.g. with VTCompressionSessionCreate()) which can release it. // To account for this possibility, conservatively stop tracking // the context. ScratchArgs = AF.add(ScratchArgs, 5, ArgEffect(StopTracking)); return getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs, ArgEffect(DoNothing), ArgEffect(DoNothing)); } else if (FName == "dispatch_set_context" || FName == "xpc_connection_set_context") { // - The analyzer currently doesn't have // a good way to reason about the finalizer function for libdispatch. // If we pass a context object that is memory managed, stop tracking it. // - Same problem, but for XPC. // FIXME: this hack should possibly go away once we can handle // libdispatch and XPC finalizers. ScratchArgs = AF.add(ScratchArgs, 1, ArgEffect(StopTracking)); return getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs, ArgEffect(DoNothing), ArgEffect(DoNothing)); } else if (FName.startswith("NSLog")) { return getDoNothingSummary(); } else if (FName.startswith("NS") && FName.contains("Insert")) { // Whitelist NSXXInsertXX, for example NSMapInsertIfAbsent, since they can // be deallocated by NSMapRemove. (radar://11152419) ScratchArgs = AF.add(ScratchArgs, 1, ArgEffect(StopTracking)); ScratchArgs = AF.add(ScratchArgs, 2, ArgEffect(StopTracking)); return getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs, ArgEffect(DoNothing), ArgEffect(DoNothing)); } if (RetTy->isPointerType()) { // For CoreFoundation ('CF') types. if (cocoa::isRefType(RetTy, "CF", FName)) { if (isRetain(FD, FName)) { // CFRetain isn't supposed to be annotated. However, this may as // well be a user-made "safe" CFRetain function that is incorrectly // annotated as cf_returns_retained due to lack of better options. // We want to ignore such annotation. AllowAnnotations = false; return getUnarySummary(FT, IncRef); } else if (isAutorelease(FD, FName)) { // The headers use cf_consumed, but we can fully model CFAutorelease // ourselves. AllowAnnotations = false; return getUnarySummary(FT, Autorelease); } else if (isMakeCollectable(FName)) { AllowAnnotations = false; return getUnarySummary(FT, DoNothing); } else { return getCFCreateGetRuleSummary(FD); } } // For CoreGraphics ('CG') and CoreVideo ('CV') types. if (cocoa::isRefType(RetTy, "CG", FName) || cocoa::isRefType(RetTy, "CV", FName)) { if (isRetain(FD, FName)) return getUnarySummary(FT, IncRef); else return getCFCreateGetRuleSummary(FD); } // For all other CF-style types, use the Create/Get // rule for summaries but don't support Retain functions // with framework-specific prefixes. if (coreFoundation::isCFObjectRef(RetTy)) { return getCFCreateGetRuleSummary(FD); } if (FD->hasAttr()) { return getCFCreateGetRuleSummary(FD); } } // Check for release functions, the only kind of functions that we care // about that don't return a pointer type. if (FName.startswith("CG") || FName.startswith("CF")) { // Test for 'CGCF'. FName = FName.substr(FName.startswith("CGCF") ? 4 : 2); if (isRelease(FD, FName)) return getUnarySummary(FT, DecRef); else { assert(ScratchArgs.isEmpty()); // Remaining CoreFoundation and CoreGraphics functions. // We use to assume that they all strictly followed the ownership idiom // and that ownership cannot be transferred. While this is technically // correct, many methods allow a tracked object to escape. For example: // // CFMutableDictionaryRef x = CFDictionaryCreateMutable(...); // CFDictionaryAddValue(y, key, x); // CFRelease(x); // ... it is okay to use 'x' since 'y' has a reference to it // // We handle this and similar cases with the follow heuristic. If the // function name contains "InsertValue", "SetValue", "AddValue", // "AppendValue", or "SetAttribute", then we assume that arguments may // "escape." This means that something else holds on to the object, // allowing it be used even after its local retain count drops to 0. ArgEffectKind E = (StrInStrNoCase(FName, "InsertValue") != StringRef::npos || StrInStrNoCase(FName, "AddValue") != StringRef::npos || StrInStrNoCase(FName, "SetValue") != StringRef::npos || StrInStrNoCase(FName, "AppendValue") != StringRef::npos || StrInStrNoCase(FName, "SetAttribute") != StringRef::npos) ? MayEscape : DoNothing; return getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs, ArgEffect(DoNothing), ArgEffect(E, ObjKind::CF)); } } return nullptr; } const RetainSummary * RetainSummaryManager::generateSummary(const FunctionDecl *FD, bool &AllowAnnotations) { // We generate "stop" summaries for implicitly defined functions. if (FD->isImplicit()) return getPersistentStopSummary(); const IdentifierInfo *II = FD->getIdentifier(); StringRef FName = II ? II->getName() : ""; // Strip away preceding '_'. Doing this here will effect all the checks // down below. FName = FName.substr(FName.find_first_not_of('_')); // Inspect the result type. Strip away any typedefs. const auto *FT = FD->getType()->castAs(); QualType RetTy = FT->getReturnType(); if (TrackOSObjects) if (const RetainSummary *S = getSummaryForOSObject(FD, FName, RetTy)) return S; if (const auto *MD = dyn_cast(FD)) if (!isOSObjectRelated(MD)) return getPersistentSummary(RetEffect::MakeNoRet(), ArgEffects(AF.getEmptyMap()), ArgEffect(DoNothing), ArgEffect(StopTracking), ArgEffect(DoNothing)); if (TrackObjCAndCFObjects) if (const RetainSummary *S = getSummaryForObjCOrCFObject(FD, FName, RetTy, FT, AllowAnnotations)) return S; return getDefaultSummary(); } const RetainSummary * RetainSummaryManager::getFunctionSummary(const FunctionDecl *FD) { // If we don't know what function we're calling, use our default summary. if (!FD) return getDefaultSummary(); // Look up a summary in our cache of FunctionDecls -> Summaries. FuncSummariesTy::iterator I = FuncSummaries.find(FD); if (I != FuncSummaries.end()) return I->second; // No summary? Generate one. bool AllowAnnotations = true; const RetainSummary *S = generateSummary(FD, AllowAnnotations); // Annotations override defaults. if (AllowAnnotations) updateSummaryFromAnnotations(S, FD); FuncSummaries[FD] = S; return S; } //===----------------------------------------------------------------------===// // Summary creation for functions (largely uses of Core Foundation). //===----------------------------------------------------------------------===// static ArgEffect getStopTrackingHardEquivalent(ArgEffect E) { switch (E.getKind()) { case DoNothing: case Autorelease: case DecRefBridgedTransferred: case IncRef: case UnretainedOutParameter: case RetainedOutParameter: case RetainedOutParameterOnZero: case RetainedOutParameterOnNonZero: case MayEscape: case StopTracking: case StopTrackingHard: return E.withKind(StopTrackingHard); case DecRef: case DecRefAndStopTrackingHard: return E.withKind(DecRefAndStopTrackingHard); case Dealloc: return E.withKind(Dealloc); } llvm_unreachable("Unknown ArgEffect kind"); } const RetainSummary * RetainSummaryManager::updateSummaryForNonZeroCallbackArg(const RetainSummary *S, AnyCall &C) { ArgEffect RecEffect = getStopTrackingHardEquivalent(S->getReceiverEffect()); ArgEffect DefEffect = getStopTrackingHardEquivalent(S->getDefaultArgEffect()); ArgEffects ScratchArgs(AF.getEmptyMap()); ArgEffects CustomArgEffects = S->getArgEffects(); for (ArgEffects::iterator I = CustomArgEffects.begin(), E = CustomArgEffects.end(); I != E; ++I) { ArgEffect Translated = getStopTrackingHardEquivalent(I->second); if (Translated.getKind() != DefEffect.getKind()) ScratchArgs = AF.add(ScratchArgs, I->first, Translated); } RetEffect RE = RetEffect::MakeNoRetHard(); // Special cases where the callback argument CANNOT free the return value. // This can generally only happen if we know that the callback will only be // called when the return value is already being deallocated. if (const IdentifierInfo *Name = C.getIdentifier()) { // When the CGBitmapContext is deallocated, the callback here will free // the associated data buffer. // The callback in dispatch_data_create frees the buffer, but not // the data object. if (Name->isStr("CGBitmapContextCreateWithData") || Name->isStr("dispatch_data_create")) RE = S->getRetEffect(); } return getPersistentSummary(RE, ScratchArgs, RecEffect, DefEffect); } void RetainSummaryManager::updateSummaryForReceiverUnconsumedSelf( const RetainSummary *&S) { RetainSummaryTemplate Template(S, *this); Template->setReceiverEffect(ArgEffect(DoNothing)); Template->setRetEffect(RetEffect::MakeNoRet()); } void RetainSummaryManager::updateSummaryForArgumentTypes( const AnyCall &C, const RetainSummary *&RS) { RetainSummaryTemplate Template(RS, *this); unsigned parm_idx = 0; for (auto pi = C.param_begin(), pe = C.param_end(); pi != pe; ++pi, ++parm_idx) { QualType QT = (*pi)->getType(); // Skip already created values. if (RS->getArgEffects().contains(parm_idx)) continue; ObjKind K = ObjKind::AnyObj; if (isISLObjectRef(QT)) { K = ObjKind::Generalized; } else if (isOSObjectPtr(QT)) { K = ObjKind::OS; } else if (cocoa::isCocoaObjectRef(QT)) { K = ObjKind::ObjC; } else if (coreFoundation::isCFObjectRef(QT)) { K = ObjKind::CF; } if (K != ObjKind::AnyObj) Template->addArg(AF, parm_idx, ArgEffect(RS->getDefaultArgEffect().getKind(), K)); } } const RetainSummary * RetainSummaryManager::getSummary(AnyCall C, bool HasNonZeroCallbackArg, bool IsReceiverUnconsumedSelf, QualType ReceiverType) { const RetainSummary *Summ; switch (C.getKind()) { case AnyCall::Function: case AnyCall::Constructor: case AnyCall::InheritedConstructor: case AnyCall::Allocator: case AnyCall::Deallocator: Summ = getFunctionSummary(cast_or_null(C.getDecl())); break; case AnyCall::Block: case AnyCall::Destructor: // FIXME: These calls are currently unsupported. return getPersistentStopSummary(); case AnyCall::ObjCMethod: { const auto *ME = cast_or_null(C.getExpr()); if (!ME) { Summ = getMethodSummary(cast(C.getDecl())); } else if (ME->isInstanceMessage()) { Summ = getInstanceMethodSummary(ME, ReceiverType); } else { Summ = getClassMethodSummary(ME); } break; } } if (HasNonZeroCallbackArg) Summ = updateSummaryForNonZeroCallbackArg(Summ, C); if (IsReceiverUnconsumedSelf) updateSummaryForReceiverUnconsumedSelf(Summ); updateSummaryForArgumentTypes(C, Summ); assert(Summ && "Unknown call type?"); return Summ; } const RetainSummary * RetainSummaryManager::getCFCreateGetRuleSummary(const FunctionDecl *FD) { if (coreFoundation::followsCreateRule(FD)) return getCFSummaryCreateRule(FD); return getCFSummaryGetRule(FD); } bool RetainSummaryManager::isTrustedReferenceCountImplementation( const Decl *FD) { return hasRCAnnotation(FD, "rc_ownership_trusted_implementation"); } Optional RetainSummaryManager::canEval(const CallExpr *CE, const FunctionDecl *FD, bool &hasTrustedImplementationAnnotation) { IdentifierInfo *II = FD->getIdentifier(); if (!II) return None; StringRef FName = II->getName(); FName = FName.substr(FName.find_first_not_of('_')); QualType ResultTy = CE->getCallReturnType(Ctx); if (ResultTy->isObjCIdType()) { if (II->isStr("NSMakeCollectable")) return BehaviorSummary::Identity; } else if (ResultTy->isPointerType()) { // Handle: (CF|CG|CV)Retain // CFAutorelease // It's okay to be a little sloppy here. if (FName == "CMBufferQueueDequeueAndRetain" || FName == "CMBufferQueueDequeueIfDataReadyAndRetain") { // Part of: . // These are not retain. They just return something and retain it. return None; } if (CE->getNumArgs() == 1 && (cocoa::isRefType(ResultTy, "CF", FName) || cocoa::isRefType(ResultTy, "CG", FName) || cocoa::isRefType(ResultTy, "CV", FName)) && (isRetain(FD, FName) || isAutorelease(FD, FName) || isMakeCollectable(FName))) return BehaviorSummary::Identity; // safeMetaCast is called by OSDynamicCast. // We assume that OSDynamicCast is either an identity (cast is OK, // the input was non-zero), // or that it returns zero (when the cast failed, or the input // was zero). if (TrackOSObjects) { if (isOSObjectDynamicCast(FName) && FD->param_size() >= 1) { return BehaviorSummary::IdentityOrZero; } else if (isOSObjectRequiredCast(FName) && FD->param_size() >= 1) { return BehaviorSummary::Identity; } else if (isOSObjectThisCast(FName) && isa(FD) && !cast(FD)->isStatic()) { return BehaviorSummary::IdentityThis; } } const FunctionDecl* FDD = FD->getDefinition(); if (FDD && isTrustedReferenceCountImplementation(FDD)) { hasTrustedImplementationAnnotation = true; return BehaviorSummary::Identity; } } if (const auto *MD = dyn_cast(FD)) { const CXXRecordDecl *Parent = MD->getParent(); if (TrackOSObjects && Parent && isOSObjectSubclass(Parent)) if (FName == "release" || FName == "retain") return BehaviorSummary::NoOp; } return None; } const RetainSummary * RetainSummaryManager::getUnarySummary(const FunctionType* FT, ArgEffectKind AE) { // Unary functions have no arg effects by definition. ArgEffects ScratchArgs(AF.getEmptyMap()); // Verify that this is *really* a unary function. This can // happen if people do weird things. const FunctionProtoType* FTP = dyn_cast(FT); if (!FTP || FTP->getNumParams() != 1) return getPersistentStopSummary(); ArgEffect Effect(AE, ObjKind::CF); ScratchArgs = AF.add(ScratchArgs, 0, Effect); return getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs, ArgEffect(DoNothing), ArgEffect(DoNothing)); } const RetainSummary * RetainSummaryManager::getOSSummaryRetainRule(const FunctionDecl *FD) { return getPersistentSummary(RetEffect::MakeNoRet(), AF.getEmptyMap(), /*ReceiverEff=*/ArgEffect(DoNothing), /*DefaultEff=*/ArgEffect(DoNothing), /*ThisEff=*/ArgEffect(IncRef, ObjKind::OS)); } const RetainSummary * RetainSummaryManager::getOSSummaryReleaseRule(const FunctionDecl *FD) { return getPersistentSummary(RetEffect::MakeNoRet(), AF.getEmptyMap(), /*ReceiverEff=*/ArgEffect(DoNothing), /*DefaultEff=*/ArgEffect(DoNothing), /*ThisEff=*/ArgEffect(DecRef, ObjKind::OS)); } const RetainSummary * RetainSummaryManager::getOSSummaryFreeRule(const FunctionDecl *FD) { return getPersistentSummary(RetEffect::MakeNoRet(), AF.getEmptyMap(), /*ReceiverEff=*/ArgEffect(DoNothing), /*DefaultEff=*/ArgEffect(DoNothing), /*ThisEff=*/ArgEffect(Dealloc, ObjKind::OS)); } const RetainSummary * RetainSummaryManager::getOSSummaryCreateRule(const FunctionDecl *FD) { return getPersistentSummary(RetEffect::MakeOwned(ObjKind::OS), AF.getEmptyMap()); } const RetainSummary * RetainSummaryManager::getOSSummaryGetRule(const FunctionDecl *FD) { return getPersistentSummary(RetEffect::MakeNotOwned(ObjKind::OS), AF.getEmptyMap()); } const RetainSummary * RetainSummaryManager::getCFSummaryCreateRule(const FunctionDecl *FD) { return getPersistentSummary(RetEffect::MakeOwned(ObjKind::CF), ArgEffects(AF.getEmptyMap())); } const RetainSummary * RetainSummaryManager::getCFSummaryGetRule(const FunctionDecl *FD) { return getPersistentSummary(RetEffect::MakeNotOwned(ObjKind::CF), ArgEffects(AF.getEmptyMap()), ArgEffect(DoNothing), ArgEffect(DoNothing)); } //===----------------------------------------------------------------------===// // Summary creation for Selectors. //===----------------------------------------------------------------------===// Optional RetainSummaryManager::getRetEffectFromAnnotations(QualType RetTy, const Decl *D) { if (hasAnyEnabledAttrOf(D, RetTy)) return ObjCAllocRetE; if (auto K = hasAnyEnabledAttrOf(D, RetTy)) return RetEffect::MakeOwned(*K); if (auto K = hasAnyEnabledAttrOf< CFReturnsNotRetainedAttr, OSReturnsNotRetainedAttr, GeneralizedReturnsNotRetainedAttr, NSReturnsNotRetainedAttr, NSReturnsAutoreleasedAttr>(D, RetTy)) return RetEffect::MakeNotOwned(*K); if (const auto *MD = dyn_cast(D)) for (const auto *PD : MD->overridden_methods()) if (auto RE = getRetEffectFromAnnotations(RetTy, PD)) return RE; return None; } /// \return Whether the chain of typedefs starting from @c QT /// has a typedef with a given name @c Name. static bool hasTypedefNamed(QualType QT, StringRef Name) { while (auto *T = dyn_cast(QT)) { const auto &Context = T->getDecl()->getASTContext(); if (T->getDecl()->getIdentifier() == &Context.Idents.get(Name)) return true; QT = T->getDecl()->getUnderlyingType(); } return false; } static QualType getCallableReturnType(const NamedDecl *ND) { if (const auto *FD = dyn_cast(ND)) { return FD->getReturnType(); } else if (const auto *MD = dyn_cast(ND)) { return MD->getReturnType(); } else { llvm_unreachable("Unexpected decl"); } } bool RetainSummaryManager::applyParamAnnotationEffect( const ParmVarDecl *pd, unsigned parm_idx, const NamedDecl *FD, RetainSummaryTemplate &Template) { QualType QT = pd->getType(); if (auto K = hasAnyEnabledAttrOf(pd, QT)) { Template->addArg(AF, parm_idx, ArgEffect(DecRef, *K)); return true; } else if (auto K = hasAnyEnabledAttrOf< CFReturnsRetainedAttr, OSReturnsRetainedAttr, OSReturnsRetainedOnNonZeroAttr, OSReturnsRetainedOnZeroAttr, GeneralizedReturnsRetainedAttr>(pd, QT)) { // For OSObjects, we try to guess whether the object is created based // on the return value. if (K == ObjKind::OS) { QualType QT = getCallableReturnType(FD); bool HasRetainedOnZero = pd->hasAttr(); bool HasRetainedOnNonZero = pd->hasAttr(); // The usual convention is to create an object on non-zero return, but // it's reverted if the typedef chain has a typedef kern_return_t, // because kReturnSuccess constant is defined as zero. // The convention can be overwritten by custom attributes. bool SuccessOnZero = HasRetainedOnZero || (hasTypedefNamed(QT, "kern_return_t") && !HasRetainedOnNonZero); bool ShouldSplit = !QT.isNull() && !QT->isVoidType(); ArgEffectKind AK = RetainedOutParameter; if (ShouldSplit && SuccessOnZero) { AK = RetainedOutParameterOnZero; } else if (ShouldSplit && (!SuccessOnZero || HasRetainedOnNonZero)) { AK = RetainedOutParameterOnNonZero; } Template->addArg(AF, parm_idx, ArgEffect(AK, ObjKind::OS)); } // For others: // Do nothing. Retained out parameters will either point to a +1 reference // or NULL, but the way you check for failure differs depending on the // API. Consequently, we don't have a good way to track them yet. return true; } else if (auto K = hasAnyEnabledAttrOf( pd, QT)) { Template->addArg(AF, parm_idx, ArgEffect(UnretainedOutParameter, *K)); return true; } if (const auto *MD = dyn_cast(FD)) { for (const auto *OD : MD->overridden_methods()) { const ParmVarDecl *OP = OD->parameters()[parm_idx]; if (applyParamAnnotationEffect(OP, parm_idx, OD, Template)) return true; } } return false; } void RetainSummaryManager::updateSummaryFromAnnotations(const RetainSummary *&Summ, const FunctionDecl *FD) { if (!FD) return; assert(Summ && "Must have a summary to add annotations to."); RetainSummaryTemplate Template(Summ, *this); // Effects on the parameters. unsigned parm_idx = 0; for (auto pi = FD->param_begin(), pe = FD->param_end(); pi != pe; ++pi, ++parm_idx) applyParamAnnotationEffect(*pi, parm_idx, FD, Template); QualType RetTy = FD->getReturnType(); if (Optional RetE = getRetEffectFromAnnotations(RetTy, FD)) Template->setRetEffect(*RetE); if (hasAnyEnabledAttrOf(FD, RetTy)) Template->setThisEffect(ArgEffect(DecRef, ObjKind::OS)); } void RetainSummaryManager::updateSummaryFromAnnotations(const RetainSummary *&Summ, const ObjCMethodDecl *MD) { if (!MD) return; assert(Summ && "Must have a valid summary to add annotations to"); RetainSummaryTemplate Template(Summ, *this); // Effects on the receiver. if (hasAnyEnabledAttrOf(MD, MD->getReturnType())) Template->setReceiverEffect(ArgEffect(DecRef, ObjKind::ObjC)); // Effects on the parameters. unsigned parm_idx = 0; for (auto pi = MD->param_begin(), pe = MD->param_end(); pi != pe; ++pi, ++parm_idx) applyParamAnnotationEffect(*pi, parm_idx, MD, Template); QualType RetTy = MD->getReturnType(); if (Optional RetE = getRetEffectFromAnnotations(RetTy, MD)) Template->setRetEffect(*RetE); } const RetainSummary * RetainSummaryManager::getStandardMethodSummary(const ObjCMethodDecl *MD, Selector S, QualType RetTy) { // Any special effects? ArgEffect ReceiverEff = ArgEffect(DoNothing, ObjKind::ObjC); RetEffect ResultEff = RetEffect::MakeNoRet(); // Check the method family, and apply any default annotations. switch (MD ? MD->getMethodFamily() : S.getMethodFamily()) { case OMF_None: case OMF_initialize: case OMF_performSelector: // Assume all Objective-C methods follow Cocoa Memory Management rules. // FIXME: Does the non-threaded performSelector family really belong here? // The selector could be, say, @selector(copy). if (cocoa::isCocoaObjectRef(RetTy)) ResultEff = RetEffect::MakeNotOwned(ObjKind::ObjC); else if (coreFoundation::isCFObjectRef(RetTy)) { // ObjCMethodDecl currently doesn't consider CF objects as valid return // values for alloc, new, copy, or mutableCopy, so we have to // double-check with the selector. This is ugly, but there aren't that // many Objective-C methods that return CF objects, right? if (MD) { switch (S.getMethodFamily()) { case OMF_alloc: case OMF_new: case OMF_copy: case OMF_mutableCopy: ResultEff = RetEffect::MakeOwned(ObjKind::CF); break; default: ResultEff = RetEffect::MakeNotOwned(ObjKind::CF); break; } } else { ResultEff = RetEffect::MakeNotOwned(ObjKind::CF); } } break; case OMF_init: ResultEff = ObjCInitRetE; ReceiverEff = ArgEffect(DecRef, ObjKind::ObjC); break; case OMF_alloc: case OMF_new: case OMF_copy: case OMF_mutableCopy: if (cocoa::isCocoaObjectRef(RetTy)) ResultEff = ObjCAllocRetE; else if (coreFoundation::isCFObjectRef(RetTy)) ResultEff = RetEffect::MakeOwned(ObjKind::CF); break; case OMF_autorelease: ReceiverEff = ArgEffect(Autorelease, ObjKind::ObjC); break; case OMF_retain: ReceiverEff = ArgEffect(IncRef, ObjKind::ObjC); break; case OMF_release: ReceiverEff = ArgEffect(DecRef, ObjKind::ObjC); break; case OMF_dealloc: ReceiverEff = ArgEffect(Dealloc, ObjKind::ObjC); break; case OMF_self: // -self is handled specially by the ExprEngine to propagate the receiver. break; case OMF_retainCount: case OMF_finalize: // These methods don't return objects. break; } // If one of the arguments in the selector has the keyword 'delegate' we // should stop tracking the reference count for the receiver. This is // because the reference count is quite possibly handled by a delegate // method. if (S.isKeywordSelector()) { for (unsigned i = 0, e = S.getNumArgs(); i != e; ++i) { StringRef Slot = S.getNameForSlot(i); if (Slot.substr(Slot.size() - 8).equals_insensitive("delegate")) { if (ResultEff == ObjCInitRetE) ResultEff = RetEffect::MakeNoRetHard(); else ReceiverEff = ArgEffect(StopTrackingHard, ObjKind::ObjC); } } } if (ReceiverEff.getKind() == DoNothing && ResultEff.getKind() == RetEffect::NoRet) return getDefaultSummary(); return getPersistentSummary(ResultEff, ArgEffects(AF.getEmptyMap()), ArgEffect(ReceiverEff), ArgEffect(MayEscape)); } const RetainSummary * RetainSummaryManager::getClassMethodSummary(const ObjCMessageExpr *ME) { assert(!ME->isInstanceMessage()); const ObjCInterfaceDecl *Class = ME->getReceiverInterface(); return getMethodSummary(ME->getSelector(), Class, ME->getMethodDecl(), ME->getType(), ObjCClassMethodSummaries); } const RetainSummary *RetainSummaryManager::getInstanceMethodSummary( const ObjCMessageExpr *ME, QualType ReceiverType) { const ObjCInterfaceDecl *ReceiverClass = nullptr; // We do better tracking of the type of the object than the core ExprEngine. // See if we have its type in our private state. if (!ReceiverType.isNull()) if (const auto *PT = ReceiverType->getAs()) ReceiverClass = PT->getInterfaceDecl(); // If we don't know what kind of object this is, fall back to its static type. if (!ReceiverClass) ReceiverClass = ME->getReceiverInterface(); // FIXME: The receiver could be a reference to a class, meaning that // we should use the class method. // id x = [NSObject class]; // [x performSelector:... withObject:... afterDelay:...]; Selector S = ME->getSelector(); const ObjCMethodDecl *Method = ME->getMethodDecl(); if (!Method && ReceiverClass) Method = ReceiverClass->getInstanceMethod(S); return getMethodSummary(S, ReceiverClass, Method, ME->getType(), ObjCMethodSummaries); } const RetainSummary * RetainSummaryManager::getMethodSummary(Selector S, const ObjCInterfaceDecl *ID, const ObjCMethodDecl *MD, QualType RetTy, ObjCMethodSummariesTy &CachedSummaries) { // Objective-C method summaries are only applicable to ObjC and CF objects. if (!TrackObjCAndCFObjects) return getDefaultSummary(); // Look up a summary in our summary cache. const RetainSummary *Summ = CachedSummaries.find(ID, S); if (!Summ) { Summ = getStandardMethodSummary(MD, S, RetTy); // Annotations override defaults. updateSummaryFromAnnotations(Summ, MD); // Memoize the summary. CachedSummaries[ObjCSummaryKey(ID, S)] = Summ; } return Summ; } void RetainSummaryManager::InitializeClassMethodSummaries() { ArgEffects ScratchArgs = AF.getEmptyMap(); // Create the [NSAssertionHandler currentHander] summary. addClassMethSummary("NSAssertionHandler", "currentHandler", getPersistentSummary(RetEffect::MakeNotOwned(ObjKind::ObjC), ScratchArgs)); // Create the [NSAutoreleasePool addObject:] summary. ScratchArgs = AF.add(ScratchArgs, 0, ArgEffect(Autorelease)); addClassMethSummary("NSAutoreleasePool", "addObject", getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs, ArgEffect(DoNothing), ArgEffect(Autorelease))); } void RetainSummaryManager::InitializeMethodSummaries() { ArgEffects ScratchArgs = AF.getEmptyMap(); // Create the "init" selector. It just acts as a pass-through for the // receiver. const RetainSummary *InitSumm = getPersistentSummary( ObjCInitRetE, ScratchArgs, ArgEffect(DecRef, ObjKind::ObjC)); addNSObjectMethSummary(GetNullarySelector("init", Ctx), InitSumm); // awakeAfterUsingCoder: behaves basically like an 'init' method. It // claims the receiver and returns a retained object. addNSObjectMethSummary(GetUnarySelector("awakeAfterUsingCoder", Ctx), InitSumm); // The next methods are allocators. const RetainSummary *AllocSumm = getPersistentSummary(ObjCAllocRetE, ScratchArgs); const RetainSummary *CFAllocSumm = getPersistentSummary(RetEffect::MakeOwned(ObjKind::CF), ScratchArgs); // Create the "retain" selector. RetEffect NoRet = RetEffect::MakeNoRet(); const RetainSummary *Summ = getPersistentSummary( NoRet, ScratchArgs, ArgEffect(IncRef, ObjKind::ObjC)); addNSObjectMethSummary(GetNullarySelector("retain", Ctx), Summ); // Create the "release" selector. Summ = getPersistentSummary(NoRet, ScratchArgs, ArgEffect(DecRef, ObjKind::ObjC)); addNSObjectMethSummary(GetNullarySelector("release", Ctx), Summ); // Create the -dealloc summary. Summ = getPersistentSummary(NoRet, ScratchArgs, ArgEffect(Dealloc, ObjKind::ObjC)); addNSObjectMethSummary(GetNullarySelector("dealloc", Ctx), Summ); // Create the "autorelease" selector. Summ = getPersistentSummary(NoRet, ScratchArgs, ArgEffect(Autorelease, ObjKind::ObjC)); addNSObjectMethSummary(GetNullarySelector("autorelease", Ctx), Summ); // For NSWindow, allocated objects are (initially) self-owned. // FIXME: For now we opt for false negatives with NSWindow, as these objects // self-own themselves. However, they only do this once they are displayed. // Thus, we need to track an NSWindow's display status. // This is tracked in . // See also http://llvm.org/bugs/show_bug.cgi?id=3714. const RetainSummary *NoTrackYet = getPersistentSummary(RetEffect::MakeNoRet(), ScratchArgs, ArgEffect(StopTracking), ArgEffect(StopTracking)); addClassMethSummary("NSWindow", "alloc", NoTrackYet); // For NSPanel (which subclasses NSWindow), allocated objects are not // self-owned. // FIXME: For now we don't track NSPanels. object for the same reason // as for NSWindow objects. addClassMethSummary("NSPanel", "alloc", NoTrackYet); // For NSNull, objects returned by +null are singletons that ignore // retain/release semantics. Just don't track them. // addClassMethSummary("NSNull", "null", NoTrackYet); // Don't track allocated autorelease pools, as it is okay to prematurely // exit a method. addClassMethSummary("NSAutoreleasePool", "alloc", NoTrackYet); addClassMethSummary("NSAutoreleasePool", "allocWithZone", NoTrackYet, false); addClassMethSummary("NSAutoreleasePool", "new", NoTrackYet); // Create summaries QCRenderer/QCView -createSnapShotImageOfType: addInstMethSummary("QCRenderer", AllocSumm, "createSnapshotImageOfType"); addInstMethSummary("QCView", AllocSumm, "createSnapshotImageOfType"); // Create summaries for CIContext, 'createCGImage' and // 'createCGLayerWithSize'. These objects are CF objects, and are not // automatically garbage collected. addInstMethSummary("CIContext", CFAllocSumm, "createCGImage", "fromRect"); addInstMethSummary("CIContext", CFAllocSumm, "createCGImage", "fromRect", "format", "colorSpace"); addInstMethSummary("CIContext", CFAllocSumm, "createCGLayerWithSize", "info"); } const RetainSummary * RetainSummaryManager::getMethodSummary(const ObjCMethodDecl *MD) { const ObjCInterfaceDecl *ID = MD->getClassInterface(); Selector S = MD->getSelector(); QualType ResultTy = MD->getReturnType(); ObjCMethodSummariesTy *CachedSummaries; if (MD->isInstanceMethod()) CachedSummaries = &ObjCMethodSummaries; else CachedSummaries = &ObjCClassMethodSummaries; return getMethodSummary(S, ID, MD, ResultTy, *CachedSummaries); }