NoReturnFunctionChecker.cpp revision 263508
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 "clang/AST/Attr.h" 17#include "clang/StaticAnalyzer/Core/Checker.h" 18#include "clang/StaticAnalyzer/Core/CheckerManager.h" 19#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" 20#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 21#include "llvm/ADT/StringSwitch.h" 22#include <cstdarg> 23 24using namespace clang; 25using namespace ento; 26 27namespace { 28 29class NoReturnFunctionChecker : public Checker< check::PostCall, 30 check::PostObjCMessage > { 31public: 32 void checkPostCall(const CallEvent &CE, CheckerContext &C) const; 33 void checkPostObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const; 34}; 35 36} 37 38void NoReturnFunctionChecker::checkPostCall(const CallEvent &CE, 39 CheckerContext &C) const { 40 ProgramStateRef state = C.getState(); 41 bool BuildSinks = false; 42 43 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(CE.getDecl())) 44 BuildSinks = FD->getAttr<AnalyzerNoReturnAttr>() || FD->isNoReturn(); 45 46 const Expr *Callee = CE.getOriginExpr(); 47 if (!BuildSinks && Callee) 48 BuildSinks = getFunctionExtInfo(Callee->getType()).getNoReturn(); 49 50 if (!BuildSinks && CE.isGlobalCFunction()) { 51 if (const IdentifierInfo *II = CE.getCalleeIdentifier()) { 52 // HACK: Some functions are not marked noreturn, and don't return. 53 // Here are a few hardwired ones. If this takes too long, we can 54 // potentially cache these results. 55 BuildSinks 56 = llvm::StringSwitch<bool>(StringRef(II->getName())) 57 .Case("exit", true) 58 .Case("panic", true) 59 .Case("error", true) 60 .Case("Assert", true) 61 // FIXME: This is just a wrapper around throwing an exception. 62 // Eventually inter-procedural analysis should handle this easily. 63 .Case("ziperr", true) 64 .Case("assfail", true) 65 .Case("db_error", true) 66 .Case("__assert", true) 67 // For the purpose of static analysis, we do not care that 68 // this MSVC function will return if the user decides to continue. 69 .Case("_wassert", true) 70 .Case("__assert_rtn", true) 71 .Case("__assert_fail", true) 72 .Case("dtrace_assfail", true) 73 .Case("yy_fatal_error", true) 74 .Case("_XCAssertionFailureHandler", true) 75 .Case("_DTAssertionFailureHandler", true) 76 .Case("_TSAssertionFailureHandler", true) 77 .Default(false); 78 } 79 } 80 81 if (BuildSinks) 82 C.generateSink(); 83} 84 85static bool END_WITH_NULL isMultiArgSelector(const Selector *Sel, ...) { 86 va_list argp; 87 va_start(argp, Sel); 88 89 unsigned Slot = 0; 90 const char *Arg; 91 while ((Arg = va_arg(argp, const char *))) { 92 if (!Sel->getNameForSlot(Slot).equals(Arg)) 93 break; // still need to va_end! 94 ++Slot; 95 } 96 97 va_end(argp); 98 99 // We only succeeded if we made it to the end of the argument list. 100 return (Arg == NULL); 101} 102 103void NoReturnFunctionChecker::checkPostObjCMessage(const ObjCMethodCall &Msg, 104 CheckerContext &C) const { 105 // Check if the method is annotated with analyzer_noreturn. 106 if (const ObjCMethodDecl *MD = Msg.getDecl()) { 107 MD = MD->getCanonicalDecl(); 108 if (MD->hasAttr<AnalyzerNoReturnAttr>()) { 109 C.generateSink(); 110 return; 111 } 112 } 113 114 // HACK: This entire check is to handle two messages in the Cocoa frameworks: 115 // -[NSAssertionHandler 116 // handleFailureInMethod:object:file:lineNumber:description:] 117 // -[NSAssertionHandler 118 // handleFailureInFunction:file:lineNumber:description:] 119 // Eventually these should be annotated with __attribute__((noreturn)). 120 // Because ObjC messages use dynamic dispatch, it is not generally safe to 121 // assume certain methods can't return. In cases where it is definitely valid, 122 // see if you can mark the methods noreturn or analyzer_noreturn instead of 123 // adding more explicit checks to this method. 124 125 if (!Msg.isInstanceMessage()) 126 return; 127 128 const ObjCInterfaceDecl *Receiver = Msg.getReceiverInterface(); 129 if (!Receiver) 130 return; 131 if (!Receiver->getIdentifier()->isStr("NSAssertionHandler")) 132 return; 133 134 Selector Sel = Msg.getSelector(); 135 switch (Sel.getNumArgs()) { 136 default: 137 return; 138 case 4: 139 if (!isMultiArgSelector(&Sel, "handleFailureInFunction", "file", 140 "lineNumber", "description", NULL)) 141 return; 142 break; 143 case 5: 144 if (!isMultiArgSelector(&Sel, "handleFailureInMethod", "object", "file", 145 "lineNumber", "description", NULL)) 146 return; 147 break; 148 } 149 150 // If we got here, it's one of the messages we care about. 151 C.generateSink(); 152} 153 154 155void ento::registerNoReturnFunctionChecker(CheckerManager &mgr) { 156 mgr.registerChecker<NoReturnFunctionChecker>(); 157} 158