1//=== NoReturnFunctionChecker.cpp -------------------------------*- 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 defines NoReturnFunctionChecker, which evaluates functions that do not 11// return to the caller. 12// 13//===----------------------------------------------------------------------===// 14 15#include "ClangSACheckers.h" 16#include "SelectorExtras.h" 17#include "clang/AST/Attr.h" 18#include "clang/StaticAnalyzer/Core/Checker.h" 19#include "clang/StaticAnalyzer/Core/CheckerManager.h" 20#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" 21#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 22#include "llvm/ADT/StringSwitch.h" 23#include <cstdarg> 24 25using namespace clang; 26using namespace ento; 27 28namespace { 29 30class NoReturnFunctionChecker : public Checker< check::PostCall, 31 check::PostObjCMessage > { 32 mutable Selector HandleFailureInFunctionSel; 33 mutable Selector HandleFailureInMethodSel; 34public: 35 void checkPostCall(const CallEvent &CE, CheckerContext &C) const; 36 void checkPostObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const; 37}; 38 39} 40 41void NoReturnFunctionChecker::checkPostCall(const CallEvent &CE, 42 CheckerContext &C) const { 43 bool BuildSinks = false; 44 45 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(CE.getDecl())) 46 BuildSinks = FD->hasAttr<AnalyzerNoReturnAttr>() || FD->isNoReturn(); 47 48 const Expr *Callee = CE.getOriginExpr(); 49 if (!BuildSinks && Callee) 50 BuildSinks = getFunctionExtInfo(Callee->getType()).getNoReturn(); 51 52 if (!BuildSinks && CE.isGlobalCFunction()) { 53 if (const IdentifierInfo *II = CE.getCalleeIdentifier()) { 54 // HACK: Some functions are not marked noreturn, and don't return. 55 // Here are a few hardwired ones. If this takes too long, we can 56 // potentially cache these results. 57 BuildSinks 58 = llvm::StringSwitch<bool>(StringRef(II->getName())) 59 .Case("exit", true) 60 .Case("panic", true) 61 .Case("error", true) 62 .Case("Assert", true) 63 // FIXME: This is just a wrapper around throwing an exception. 64 // Eventually inter-procedural analysis should handle this easily. 65 .Case("ziperr", true) 66 .Case("assfail", true) 67 .Case("db_error", true) 68 .Case("__assert", true) 69 // For the purpose of static analysis, we do not care that 70 // this MSVC function will return if the user decides to continue. 71 .Case("_wassert", true) 72 .Case("__assert_rtn", true) 73 .Case("__assert_fail", true) 74 .Case("dtrace_assfail", true) 75 .Case("yy_fatal_error", true) 76 .Case("_XCAssertionFailureHandler", true) 77 .Case("_DTAssertionFailureHandler", true) 78 .Case("_TSAssertionFailureHandler", true) 79 .Default(false); 80 } 81 } 82 83 if (BuildSinks) 84 C.generateSink(); 85} 86 87void NoReturnFunctionChecker::checkPostObjCMessage(const ObjCMethodCall &Msg, 88 CheckerContext &C) const { 89 // Check if the method is annotated with analyzer_noreturn. 90 if (const ObjCMethodDecl *MD = Msg.getDecl()) { 91 MD = MD->getCanonicalDecl(); 92 if (MD->hasAttr<AnalyzerNoReturnAttr>()) { 93 C.generateSink(); 94 return; 95 } 96 } 97 98 // HACK: This entire check is to handle two messages in the Cocoa frameworks: 99 // -[NSAssertionHandler 100 // handleFailureInMethod:object:file:lineNumber:description:] 101 // -[NSAssertionHandler 102 // handleFailureInFunction:file:lineNumber:description:] 103 // Eventually these should be annotated with __attribute__((noreturn)). 104 // Because ObjC messages use dynamic dispatch, it is not generally safe to 105 // assume certain methods can't return. In cases where it is definitely valid, 106 // see if you can mark the methods noreturn or analyzer_noreturn instead of 107 // adding more explicit checks to this method. 108 109 if (!Msg.isInstanceMessage()) 110 return; 111 112 const ObjCInterfaceDecl *Receiver = Msg.getReceiverInterface(); 113 if (!Receiver) 114 return; 115 if (!Receiver->getIdentifier()->isStr("NSAssertionHandler")) 116 return; 117 118 Selector Sel = Msg.getSelector(); 119 switch (Sel.getNumArgs()) { 120 default: 121 return; 122 case 4: 123 lazyInitKeywordSelector(HandleFailureInFunctionSel, C.getASTContext(), 124 "handleFailureInFunction", "file", "lineNumber", 125 "description", nullptr); 126 if (Sel != HandleFailureInFunctionSel) 127 return; 128 break; 129 case 5: 130 lazyInitKeywordSelector(HandleFailureInMethodSel, C.getASTContext(), 131 "handleFailureInMethod", "object", "file", 132 "lineNumber", "description", nullptr); 133 if (Sel != HandleFailureInMethodSel) 134 return; 135 break; 136 } 137 138 // If we got here, it's one of the messages we care about. 139 C.generateSink(); 140} 141 142void ento::registerNoReturnFunctionChecker(CheckerManager &mgr) { 143 mgr.registerChecker<NoReturnFunctionChecker>(); 144} 145