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      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 
     25 using namespace clang;
     26 using namespace ento;
     27 
     28 namespace {
     29 
     30 class NoReturnFunctionChecker : public Checker< check::PostCall,
     31                                                 check::PostObjCMessage > {
     32   mutable Selector HandleFailureInFunctionSel;
     33   mutable Selector HandleFailureInMethodSel;
     34 public:
     35   void checkPostCall(const CallEvent &CE, CheckerContext &C) const;
     36   void checkPostObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
     37 };
     38 
     39 }
     40 
     41 void 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 
     87 void 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 
    142 void ento::registerNoReturnFunctionChecker(CheckerManager &mgr) {
    143   mgr.registerChecker<NoReturnFunctionChecker>();
    144 }
    145