//== PutenvWithAutoChecker.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 file defines PutenvWithAutoChecker which finds calls of ``putenv``

// function with automatic variable as the argument.

// https://wiki.sei.cmu.edu/confluence/x/6NYxBQ

//

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

#include "../AllocationState.h"

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

#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"

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

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

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

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

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

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

using namespace clang;

using namespace ento;

namespace {

class PutenvWithAutoChecker : public Checker<check::PostCall> {

private:

  BugType BT{this, "'putenv' function should not be called with auto variables",

             categories::SecurityError};

  const CallDescription Putenv{{"putenv"}, 1};

public:

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

};

} // namespace

void PutenvWithAutoChecker::checkPostCall(const CallEvent &Call,

                                          CheckerContext &C) const {

  if (!Putenv.matches(Call))

    return;

  SVal ArgV = Call.getArgSVal(0);

  const Expr *ArgExpr = Call.getArgExpr(0);

  const MemSpaceRegion *MSR = ArgV.getAsRegion()->getMemorySpace();

  if (!isa<StackSpaceRegion>(MSR))

    return;

  StringRef ErrorMsg = "The 'putenv' function should not be called with "

                       "arguments that have automatic storage";

  ExplodedNode *N = C.generateErrorNode();

  auto Report = std::make_unique<PathSensitiveBugReport>(BT, ErrorMsg, N);

  // Track the argument.

  bugreporter::trackExpressionValue(Report->getErrorNode(), ArgExpr, *Report);

  C.emitReport(std::move(Report));

}

void ento::registerPutenvWithAuto(CheckerManager &Mgr) {

  Mgr.registerChecker<PutenvWithAutoChecker>();

}

bool ento::shouldRegisterPutenvWithAuto(const CheckerManager &) { return true; }