//=== NoReturnFunctionChecker.cpp -------------------------------*- 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 defines NoReturnFunctionChecker, which evaluates functions that do not

// return to the caller.

//

//===----------------------------------------------------------------------===//

#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"

#include "clang/AST/Attr.h"

#include "clang/Analysis/SelectorExtras.h"

#include "clang/StaticAnalyzer/Core/Checker.h"

#include "clang/StaticAnalyzer/Core/CheckerManager.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"

#include "llvm/ADT/StringSwitch.h"

#include <cstdarg>

using namespace clang;

using namespace ento;

namespace {

class NoReturnFunctionChecker : public Checker< check::PostCall,

                                                check::PostObjCMessage > {

  mutable Selector HandleFailureInFunctionSel;

  mutable Selector HandleFailureInMethodSel;

public:

  void checkPostCall(const CallEvent &CE, CheckerContext &C) const;

  void checkPostObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;

};

}

void NoReturnFunctionChecker::checkPostCall(const CallEvent &CE,

                                            CheckerContext &C) const {

  bool BuildSinks = false;

  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(CE.getDecl()))

    BuildSinks = FD->hasAttr<AnalyzerNoReturnAttr>() || 
FD->isNoReturn()105k
;

  if (const CallExpr *CExpr = dyn_cast_or_null<CallExpr>(CE.getOriginExpr());

      CExpr && 
!BuildSinks79.6k
) {

    if (const Expr *C = CExpr->getCallee())

      BuildSinks = getFunctionExtInfo(C->getType()).getNoReturn();

  }

  if (!BuildSinks && 
CE.isGlobalCFunction()109k
) {

    if (const IdentifierInfo *II = CE.getCalleeIdentifier()) {

      // HACK: Some functions are not marked noreturn, and don't return.

      //  Here are a few hardwired ones.  If this takes too long, we can

      //  potentially cache these results.

      BuildSinks

        = llvm::StringSwitch<bool>(StringRef(II->getName()))

            .Case("exit", true)

            .Case("panic", true)

            .Case("error", true)

            .Case("Assert", true)

            // FIXME: This is just a wrapper around throwing an exception.

            //  Eventually inter-procedural analysis should handle this easily.

            .Case("ziperr", true)

            .Case("assfail", true)

            .Case("db_error", true)

            .Case("__assert", true)

            .Case("__assert2", true)

            // For the purpose of static analysis, we do not care that

            //  this MSVC function will return if the user decides to continue.

            .Case("_wassert", true)

            .Case("__assert_rtn", true)

            .Case("__assert_fail", true)

            .Case("dtrace_assfail", true)

            .Case("yy_fatal_error", true)

            .Case("_XCAssertionFailureHandler", true)

            .Case("_DTAssertionFailureHandler", true)

            .Case("_TSAssertionFailureHandler", true)

            .Default(false);

    }

  }

  if (BuildSinks)

    C.generateSink(C.getState(), C.getPredecessor());

}

void NoReturnFunctionChecker::checkPostObjCMessage(const ObjCMethodCall &Msg,

                                                   CheckerContext &C) const {

  // Check if the method is annotated with analyzer_noreturn.

  if (const ObjCMethodDecl *MD = Msg.getDecl()) {

    MD = MD->getCanonicalDecl();

    if (MD->hasAttr<AnalyzerNoReturnAttr>()) {

      C.generateSink(C.getState(), C.getPredecessor());

      return;

    }

  }

  // HACK: This entire check is to handle two messages in the Cocoa frameworks:

  // -[NSAssertionHandler

  //    handleFailureInMethod:object:file:lineNumber:description:]

  // -[NSAssertionHandler

  //    handleFailureInFunction:file:lineNumber:description:]

  // Eventually these should be annotated with __attribute__((noreturn)).

  // Because ObjC messages use dynamic dispatch, it is not generally safe to

  // assume certain methods can't return. In cases where it is definitely valid,

  // see if you can mark the methods noreturn or analyzer_noreturn instead of

  // adding more explicit checks to this method.

  if (!Msg.isInstanceMessage())

    return;

  const ObjCInterfaceDecl *Receiver = Msg.getReceiverInterface();

  if (!Receiver)

    return;

  if (!Receiver->getIdentifier()->isStr("NSAssertionHandler"))

    return;

  Selector Sel = Msg.getSelector();

  switch (Sel.getNumArgs()) {

  default:

    return;

  case 4:

    lazyInitKeywordSelector(HandleFailureInFunctionSel, C.getASTContext(),

                            "handleFailureInFunction", "file", "lineNumber",

                            "description");

    if (Sel != HandleFailureInFunctionSel)

      return;

    break;

  case 5:

    lazyInitKeywordSelector(HandleFailureInMethodSel, C.getASTContext(),

                            "handleFailureInMethod", "object", "file",

                            "lineNumber", "description");

    if (Sel != HandleFailureInMethodSel)

      return;

    break;

  }

  // If we got here, it's one of the messages we care about.

  C.generateSink(C.getState(), C.getPredecessor());

}

void ento::registerNoReturnFunctionChecker(CheckerManager &mgr) {

  mgr.registerChecker<NoReturnFunctionChecker>();

}

bool ento::shouldRegisterNoReturnFunctionChecker(const CheckerManager &mgr) {

  return true;

}