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	LLVM:1.1.1;
locks; strict;
comment	@// @;


1.1
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1.1.1.1
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1.1.1.2
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desc
@@


1.1
log
@Initial revision
@
text
@//===-- StreamChecker.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 checkers that model and check stream handling functions.
//
//===----------------------------------------------------------------------===//

#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/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"

using namespace clang;
using namespace ento;

namespace {

struct StreamState {
  enum Kind { Opened, Closed, OpenFailed, Escaped } K;
  const Stmt *S;

  StreamState(Kind k, const Stmt *s) : K(k), S(s) {}

  bool isOpened() const { return K == Opened; }
  bool isClosed() const { return K == Closed; }
  //bool isOpenFailed() const { return K == OpenFailed; }
  //bool isEscaped() const { return K == Escaped; }

  bool operator==(const StreamState &X) const {
    return K == X.K && S == X.S;
  }

  static StreamState getOpened(const Stmt *s) { return StreamState(Opened, s); }
  static StreamState getClosed(const Stmt *s) { return StreamState(Closed, s); }
  static StreamState getOpenFailed(const Stmt *s) {
    return StreamState(OpenFailed, s);
  }
  static StreamState getEscaped(const Stmt *s) {
    return StreamState(Escaped, s);
  }

  void Profile(llvm::FoldingSetNodeID &ID) const {
    ID.AddInteger(K);
    ID.AddPointer(S);
  }
};

class StreamChecker : public Checker<eval::Call,
                                     check::DeadSymbols > {
  mutable IdentifierInfo *II_fopen, *II_tmpfile, *II_fclose, *II_fread,
                 *II_fwrite,
                 *II_fseek, *II_ftell, *II_rewind, *II_fgetpos, *II_fsetpos,
                 *II_clearerr, *II_feof, *II_ferror, *II_fileno;
  mutable std::unique_ptr<BuiltinBug> BT_nullfp, BT_illegalwhence,
      BT_doubleclose, BT_ResourceLeak;

public:
  StreamChecker()
    : II_fopen(nullptr), II_tmpfile(nullptr), II_fclose(nullptr),
      II_fread(nullptr), II_fwrite(nullptr), II_fseek(nullptr),
      II_ftell(nullptr), II_rewind(nullptr), II_fgetpos(nullptr),
      II_fsetpos(nullptr), II_clearerr(nullptr), II_feof(nullptr),
      II_ferror(nullptr), II_fileno(nullptr) {}

  bool evalCall(const CallEvent &Call, CheckerContext &C) const;
  void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;

private:
  void Fopen(CheckerContext &C, const CallExpr *CE) const;
  void Tmpfile(CheckerContext &C, const CallExpr *CE) const;
  void Fclose(CheckerContext &C, const CallExpr *CE) const;
  void Fread(CheckerContext &C, const CallExpr *CE) const;
  void Fwrite(CheckerContext &C, const CallExpr *CE) const;
  void Fseek(CheckerContext &C, const CallExpr *CE) const;
  void Ftell(CheckerContext &C, const CallExpr *CE) const;
  void Rewind(CheckerContext &C, const CallExpr *CE) const;
  void Fgetpos(CheckerContext &C, const CallExpr *CE) const;
  void Fsetpos(CheckerContext &C, const CallExpr *CE) const;
  void Clearerr(CheckerContext &C, const CallExpr *CE) const;
  void Feof(CheckerContext &C, const CallExpr *CE) const;
  void Ferror(CheckerContext &C, const CallExpr *CE) const;
  void Fileno(CheckerContext &C, const CallExpr *CE) const;

  void OpenFileAux(CheckerContext &C, const CallExpr *CE) const;

  ProgramStateRef CheckNullStream(SVal SV, ProgramStateRef state,
                                 CheckerContext &C) const;
  ProgramStateRef CheckDoubleClose(const CallExpr *CE, ProgramStateRef state,
                                 CheckerContext &C) const;
};

} // end anonymous namespace

REGISTER_MAP_WITH_PROGRAMSTATE(StreamMap, SymbolRef, StreamState)


bool StreamChecker::evalCall(const CallEvent &Call, CheckerContext &C) const {
  const auto *FD = dyn_cast_or_null<FunctionDecl>(Call.getDecl());
  if (!FD || FD->getKind() != Decl::Function)
    return false;

  const auto *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
    return false;

  ASTContext &Ctx = C.getASTContext();
  if (!II_fopen)
    II_fopen = &Ctx.Idents.get("fopen");
  if (!II_tmpfile)
    II_tmpfile = &Ctx.Idents.get("tmpfile");
  if (!II_fclose)
    II_fclose = &Ctx.Idents.get("fclose");
  if (!II_fread)
    II_fread = &Ctx.Idents.get("fread");
  if (!II_fwrite)
    II_fwrite = &Ctx.Idents.get("fwrite");
  if (!II_fseek)
    II_fseek = &Ctx.Idents.get("fseek");
  if (!II_ftell)
    II_ftell = &Ctx.Idents.get("ftell");
  if (!II_rewind)
    II_rewind = &Ctx.Idents.get("rewind");
  if (!II_fgetpos)
    II_fgetpos = &Ctx.Idents.get("fgetpos");
  if (!II_fsetpos)
    II_fsetpos = &Ctx.Idents.get("fsetpos");
  if (!II_clearerr)
    II_clearerr = &Ctx.Idents.get("clearerr");
  if (!II_feof)
    II_feof = &Ctx.Idents.get("feof");
  if (!II_ferror)
    II_ferror = &Ctx.Idents.get("ferror");
  if (!II_fileno)
    II_fileno = &Ctx.Idents.get("fileno");

  if (FD->getIdentifier() == II_fopen) {
    Fopen(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_tmpfile) {
    Tmpfile(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_fclose) {
    Fclose(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_fread) {
    Fread(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_fwrite) {
    Fwrite(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_fseek) {
    Fseek(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_ftell) {
    Ftell(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_rewind) {
    Rewind(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_fgetpos) {
    Fgetpos(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_fsetpos) {
    Fsetpos(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_clearerr) {
    Clearerr(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_feof) {
    Feof(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_ferror) {
    Ferror(C, CE);
    return true;
  }
  if (FD->getIdentifier() == II_fileno) {
    Fileno(C, CE);
    return true;
  }

  return false;
}

void StreamChecker::Fopen(CheckerContext &C, const CallExpr *CE) const {
  OpenFileAux(C, CE);
}

void StreamChecker::Tmpfile(CheckerContext &C, const CallExpr *CE) const {
  OpenFileAux(C, CE);
}

void StreamChecker::OpenFileAux(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  SValBuilder &svalBuilder = C.getSValBuilder();
  const LocationContext *LCtx = C.getPredecessor()->getLocationContext();
  DefinedSVal RetVal = svalBuilder.conjureSymbolVal(nullptr, CE, LCtx,
                                                    C.blockCount())
      .castAs<DefinedSVal>();
  state = state->BindExpr(CE, C.getLocationContext(), RetVal);

  ConstraintManager &CM = C.getConstraintManager();
  // Bifurcate the state into two: one with a valid FILE* pointer, the other
  // with a NULL.
  ProgramStateRef stateNotNull, stateNull;
  std::tie(stateNotNull, stateNull) = CM.assumeDual(state, RetVal);

  if (SymbolRef Sym = RetVal.getAsSymbol()) {
    // if RetVal is not NULL, set the symbol's state to Opened.
    stateNotNull =
      stateNotNull->set<StreamMap>(Sym,StreamState::getOpened(CE));
    stateNull =
      stateNull->set<StreamMap>(Sym, StreamState::getOpenFailed(CE));

    C.addTransition(stateNotNull);
    C.addTransition(stateNull);
  }
}

void StreamChecker::Fclose(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = CheckDoubleClose(CE, C.getState(), C);
  if (state)
    C.addTransition(state);
}

void StreamChecker::Fread(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  if (!CheckNullStream(C.getSVal(CE->getArg(3)), state, C))
    return;
}

void StreamChecker::Fwrite(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  if (!CheckNullStream(C.getSVal(CE->getArg(3)), state, C))
    return;
}

void StreamChecker::Fseek(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  if (!(state = CheckNullStream(C.getSVal(CE->getArg(0)), state, C)))
    return;
  // Check the legality of the 'whence' argument of 'fseek'.
  SVal Whence = state->getSVal(CE->getArg(2), C.getLocationContext());
  Optional<nonloc::ConcreteInt> CI = Whence.getAs<nonloc::ConcreteInt>();

  if (!CI)
    return;

  int64_t x = CI->getValue().getSExtValue();
  if (x >= 0 && x <= 2)
    return;

  if (ExplodedNode *N = C.generateNonFatalErrorNode(state)) {
    if (!BT_illegalwhence)
      BT_illegalwhence.reset(
          new BuiltinBug(this, "Illegal whence argument",
                         "The whence argument to fseek() should be "
                         "SEEK_SET, SEEK_END, or SEEK_CUR."));
    C.emitReport(std::make_unique<PathSensitiveBugReport>(
        *BT_illegalwhence, BT_illegalwhence->getDescription(), N));
  }
}

void StreamChecker::Ftell(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  if (!CheckNullStream(C.getSVal(CE->getArg(0)), state, C))
    return;
}

void StreamChecker::Rewind(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  if (!CheckNullStream(C.getSVal(CE->getArg(0)), state, C))
    return;
}

void StreamChecker::Fgetpos(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  if (!CheckNullStream(C.getSVal(CE->getArg(0)), state, C))
    return;
}

void StreamChecker::Fsetpos(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  if (!CheckNullStream(C.getSVal(CE->getArg(0)), state, C))
    return;
}

void StreamChecker::Clearerr(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  if (!CheckNullStream(C.getSVal(CE->getArg(0)), state, C))
    return;
}

void StreamChecker::Feof(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  if (!CheckNullStream(C.getSVal(CE->getArg(0)), state, C))
    return;
}

void StreamChecker::Ferror(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  if (!CheckNullStream(C.getSVal(CE->getArg(0)), state, C))
    return;
}

void StreamChecker::Fileno(CheckerContext &C, const CallExpr *CE) const {
  ProgramStateRef state = C.getState();
  if (!CheckNullStream(C.getSVal(CE->getArg(0)), state, C))
    return;
}

ProgramStateRef StreamChecker::CheckNullStream(SVal SV, ProgramStateRef state,
                                    CheckerContext &C) const {
  Optional<DefinedSVal> DV = SV.getAs<DefinedSVal>();
  if (!DV)
    return nullptr;

  ConstraintManager &CM = C.getConstraintManager();
  ProgramStateRef stateNotNull, stateNull;
  std::tie(stateNotNull, stateNull) = CM.assumeDual(state, *DV);

  if (!stateNotNull && stateNull) {
    if (ExplodedNode *N = C.generateErrorNode(stateNull)) {
      if (!BT_nullfp)
        BT_nullfp.reset(new BuiltinBug(this, "NULL stream pointer",
                                       "Stream pointer might be NULL."));
      C.emitReport(std::make_unique<PathSensitiveBugReport>(
          *BT_nullfp, BT_nullfp->getDescription(), N));
    }
    return nullptr;
  }
  return stateNotNull;
}

ProgramStateRef StreamChecker::CheckDoubleClose(const CallExpr *CE,
                                               ProgramStateRef state,
                                               CheckerContext &C) const {
  SymbolRef Sym = C.getSVal(CE->getArg(0)).getAsSymbol();
  if (!Sym)
    return state;

  const StreamState *SS = state->get<StreamMap>(Sym);

  // If the file stream is not tracked, return.
  if (!SS)
    return state;

  // Check: Double close a File Descriptor could cause undefined behaviour.
  // Conforming to man-pages
  if (SS->isClosed()) {
    ExplodedNode *N = C.generateErrorNode();
    if (N) {
      if (!BT_doubleclose)
        BT_doubleclose.reset(new BuiltinBug(
            this, "Double fclose", "Try to close a file Descriptor already"
                                   " closed. Cause undefined behaviour."));
      C.emitReport(std::make_unique<PathSensitiveBugReport>(
          *BT_doubleclose, BT_doubleclose->getDescription(), N));
    }
    return nullptr;
  }

  // Close the File Descriptor.
  return state->set<StreamMap>(Sym, StreamState::getClosed(CE));
}

void StreamChecker::checkDeadSymbols(SymbolReaper &SymReaper,
                                     CheckerContext &C) const {
  ProgramStateRef state = C.getState();

  // TODO: Clean up the state.
  const StreamMapTy &Map = state->get<StreamMap>();
  for (const auto &I: Map) {
    SymbolRef Sym = I.first;
    const StreamState &SS = I.second;
    if (!SymReaper.isDead(Sym) || !SS.isOpened())
      continue;

    ExplodedNode *N = C.generateErrorNode();
    if (!N)
      return;

    if (!BT_ResourceLeak)
      BT_ResourceLeak.reset(
          new BuiltinBug(this, "Resource Leak",
                         "Opened File never closed. Potential Resource leak."));
    C.emitReport(std::make_unique<PathSensitiveBugReport>(
        *BT_ResourceLeak, BT_ResourceLeak->getDescription(), N));
  }
}

void ento::registerStreamChecker(CheckerManager &mgr) {
  mgr.registerChecker<StreamChecker>();
}

bool ento::shouldRegisterStreamChecker(const LangOptions &LO) {
  return true;
}
@


1.1.1.1
log
@Import 01f3a59fb3e2542fce74c768718f594d0debd0da from the LLVM mono-repo:
clang (without test/, unittests/, www/)
llvm (without test/, unittests/)
@
text
@@


1.1.1.1.4.1
log
@sync with head
@
text
@a21 1
#include <functional>
a24 1
using namespace std::placeholders;
d28 3
a30 1
struct FnDescription;
d32 1
a32 13
/// State of the stream error flags.
/// Sometimes it is not known to the checker what error flags are set.
/// This is indicated by setting more than one flag to true.
/// This is an optimization to avoid state splits.
/// A stream can either be in FEOF or FERROR but not both at the same time.
/// Multiple flags are set to handle the corresponding states together.
struct StreamErrorState {
  /// The stream can be in state where none of the error flags set.
  bool NoError = true;
  /// The stream can be in state where the EOF indicator is set.
  bool FEof = false;
  /// The stream can be in state where the error indicator is set.
  bool FError = false;
d34 4
a37 3
  bool isNoError() const { return NoError && !FEof && !FError; }
  bool isFEof() const { return !NoError && FEof && !FError; }
  bool isFError() const { return !NoError && !FEof && FError; }
d39 2
a40 2
  bool operator==(const StreamErrorState &ES) const {
    return NoError == ES.NoError && FEof == ES.FEof && FError == ES.FError;
d43 4
a46 4
  bool operator!=(const StreamErrorState &ES) const { return !(*this == ES); }

  StreamErrorState operator|(const StreamErrorState &E) const {
    return {NoError || E.NoError, FEof || E.FEof, FError || E.FError};
d48 2
a49 3

  StreamErrorState operator&(const StreamErrorState &E) const {
    return {NoError && E.NoError, FEof && E.FEof, FError && E.FError};
a51 5
  StreamErrorState operator~() const { return {!NoError, !FEof, !FError}; }

  /// Returns if the StreamErrorState is a valid object.
  operator bool() const { return NoError || FEof || FError; }

d53 2
a54 3
    ID.AddBoolean(NoError);
    ID.AddBoolean(FEof);
    ID.AddBoolean(FError);
d58 8
a65 3
const StreamErrorState ErrorNone{true, false, false};
const StreamErrorState ErrorFEof{false, true, false};
const StreamErrorState ErrorFError{false, false, true};
d67 7
a73 89
/// Full state information about a stream pointer.
struct StreamState {
  /// The last file operation called in the stream.
  const FnDescription *LastOperation;

  /// State of a stream symbol.
  /// FIXME: We need maybe an "escaped" state later.
  enum KindTy {
    Opened, /// Stream is opened.
    Closed, /// Closed stream (an invalid stream pointer after it was closed).
    OpenFailed /// The last open operation has failed.
  } State;

  /// State of the error flags.
  /// Ignored in non-opened stream state but must be NoError.
  StreamErrorState const ErrorState;

  /// Indicate if the file has an "indeterminate file position indicator".
  /// This can be set at a failing read or write or seek operation.
  /// If it is set no more read or write is allowed.
  /// This value is not dependent on the stream error flags:
  /// The error flag may be cleared with `clearerr` but the file position
  /// remains still indeterminate.
  /// This value applies to all error states in ErrorState except FEOF.
  /// An EOF+indeterminate state is the same as EOF state.
  bool const FilePositionIndeterminate = false;

  StreamState(const FnDescription *L, KindTy S, const StreamErrorState &ES,
              bool IsFilePositionIndeterminate)
      : LastOperation(L), State(S), ErrorState(ES),
        FilePositionIndeterminate(IsFilePositionIndeterminate) {
    assert((!ES.isFEof() || !IsFilePositionIndeterminate) &&
           "FilePositionIndeterminate should be false in FEof case.");
    assert((State == Opened || ErrorState.isNoError()) &&
           "ErrorState should be None in non-opened stream state.");
  }

  bool isOpened() const { return State == Opened; }
  bool isClosed() const { return State == Closed; }
  bool isOpenFailed() const { return State == OpenFailed; }

  bool operator==(const StreamState &X) const {
    // In not opened state error state should always NoError, so comparison
    // here is no problem.
    return LastOperation == X.LastOperation && State == X.State &&
           ErrorState == X.ErrorState &&
           FilePositionIndeterminate == X.FilePositionIndeterminate;
  }

  static StreamState getOpened(const FnDescription *L,
                               const StreamErrorState &ES = ErrorNone,
                               bool IsFilePositionIndeterminate = false) {
    return StreamState{L, Opened, ES, IsFilePositionIndeterminate};
  }
  static StreamState getClosed(const FnDescription *L) {
    return StreamState{L, Closed, {}, false};
  }
  static StreamState getOpenFailed(const FnDescription *L) {
    return StreamState{L, OpenFailed, {}, false};
  }

  void Profile(llvm::FoldingSetNodeID &ID) const {
    ID.AddPointer(LastOperation);
    ID.AddInteger(State);
    ID.AddInteger(ErrorState);
    ID.AddBoolean(FilePositionIndeterminate);
  }
};

class StreamChecker;
using FnCheck = std::function<void(const StreamChecker *, const FnDescription *,
                                   const CallEvent &, CheckerContext &)>;

using ArgNoTy = unsigned int;
static const ArgNoTy ArgNone = std::numeric_limits<ArgNoTy>::max();

struct FnDescription {
  FnCheck PreFn;
  FnCheck EvalFn;
  ArgNoTy StreamArgNo;
};

/// Get the value of the stream argument out of the passed call event.
/// The call should contain a function that is described by Desc.
SVal getStreamArg(const FnDescription *Desc, const CallEvent &Call) {
  assert(Desc && Desc->StreamArgNo != ArgNone &&
         "Try to get a non-existing stream argument.");
  return Call.getArgSVal(Desc->StreamArgNo);
}
a74 42
/// Create a conjured symbol return value for a call expression.
DefinedSVal makeRetVal(CheckerContext &C, const CallExpr *CE) {
  assert(CE && "Expecting a call expression.");

  const LocationContext *LCtx = C.getLocationContext();
  return C.getSValBuilder()
      .conjureSymbolVal(nullptr, CE, LCtx, C.blockCount())
      .castAs<DefinedSVal>();
}

ProgramStateRef bindAndAssumeTrue(ProgramStateRef State, CheckerContext &C,
                                  const CallExpr *CE) {
  DefinedSVal RetVal = makeRetVal(C, CE);
  State = State->BindExpr(CE, C.getLocationContext(), RetVal);
  State = State->assume(RetVal, true);
  assert(State && "Assumption on new value should not fail.");
  return State;
}

ProgramStateRef bindInt(uint64_t Value, ProgramStateRef State,
                        CheckerContext &C, const CallExpr *CE) {
  State = State->BindExpr(CE, C.getLocationContext(),
                          C.getSValBuilder().makeIntVal(Value, false));
  return State;
}

class StreamChecker : public Checker<check::PreCall, eval::Call,
                                     check::DeadSymbols, check::PointerEscape> {
  BugType BT_FileNull{this, "NULL stream pointer", "Stream handling error"};
  BugType BT_UseAfterClose{this, "Closed stream", "Stream handling error"};
  BugType BT_UseAfterOpenFailed{this, "Invalid stream",
                                "Stream handling error"};
  BugType BT_IndeterminatePosition{this, "Invalid stream state",
                                   "Stream handling error"};
  BugType BT_IllegalWhence{this, "Illegal whence argument",
                           "Stream handling error"};
  BugType BT_StreamEof{this, "Stream already in EOF", "Stream handling error"};
  BugType BT_ResourceLeak{this, "Resource leak", "Stream handling error",
                          /*SuppressOnSink =*/true};

public:
  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
a76 7
  ProgramStateRef checkPointerEscape(ProgramStateRef State,
                                     const InvalidatedSymbols &Escaped,
                                     const CallEvent *Call,
                                     PointerEscapeKind Kind) const;

  /// If true, evaluate special testing stream functions.
  bool TestMode = false;
d79 21
a99 166
  CallDescriptionMap<FnDescription> FnDescriptions = {
      {{"fopen"}, {nullptr, &StreamChecker::evalFopen, ArgNone}},
      {{"freopen", 3},
       {&StreamChecker::preFreopen, &StreamChecker::evalFreopen, 2}},
      {{"tmpfile"}, {nullptr, &StreamChecker::evalFopen, ArgNone}},
      {{"fclose", 1},
       {&StreamChecker::preDefault, &StreamChecker::evalFclose, 0}},
      {{"fread", 4},
       {&StreamChecker::preFread,
        std::bind(&StreamChecker::evalFreadFwrite, _1, _2, _3, _4, true), 3}},
      {{"fwrite", 4},
       {&StreamChecker::preFwrite,
        std::bind(&StreamChecker::evalFreadFwrite, _1, _2, _3, _4, false), 3}},
      {{"fseek", 3}, {&StreamChecker::preFseek, &StreamChecker::evalFseek, 0}},
      {{"ftell", 1}, {&StreamChecker::preDefault, nullptr, 0}},
      {{"rewind", 1}, {&StreamChecker::preDefault, nullptr, 0}},
      {{"fgetpos", 2}, {&StreamChecker::preDefault, nullptr, 0}},
      {{"fsetpos", 2}, {&StreamChecker::preDefault, nullptr, 0}},
      {{"clearerr", 1},
       {&StreamChecker::preDefault, &StreamChecker::evalClearerr, 0}},
      {{"feof", 1},
       {&StreamChecker::preDefault,
        std::bind(&StreamChecker::evalFeofFerror, _1, _2, _3, _4, ErrorFEof),
        0}},
      {{"ferror", 1},
       {&StreamChecker::preDefault,
        std::bind(&StreamChecker::evalFeofFerror, _1, _2, _3, _4, ErrorFError),
        0}},
      {{"fileno", 1}, {&StreamChecker::preDefault, nullptr, 0}},
  };

  CallDescriptionMap<FnDescription> FnTestDescriptions = {
      {{"StreamTesterChecker_make_feof_stream", 1},
       {nullptr,
        std::bind(&StreamChecker::evalSetFeofFerror, _1, _2, _3, _4, ErrorFEof),
        0}},
      {{"StreamTesterChecker_make_ferror_stream", 1},
       {nullptr,
        std::bind(&StreamChecker::evalSetFeofFerror, _1, _2, _3, _4,
                  ErrorFError),
        0}},
  };

  void evalFopen(const FnDescription *Desc, const CallEvent &Call,
                 CheckerContext &C) const;

  void preFreopen(const FnDescription *Desc, const CallEvent &Call,
                  CheckerContext &C) const;
  void evalFreopen(const FnDescription *Desc, const CallEvent &Call,
                   CheckerContext &C) const;

  void evalFclose(const FnDescription *Desc, const CallEvent &Call,
                  CheckerContext &C) const;

  void preFread(const FnDescription *Desc, const CallEvent &Call,
                CheckerContext &C) const;

  void preFwrite(const FnDescription *Desc, const CallEvent &Call,
                 CheckerContext &C) const;

  void evalFreadFwrite(const FnDescription *Desc, const CallEvent &Call,
                       CheckerContext &C, bool IsFread) const;

  void preFseek(const FnDescription *Desc, const CallEvent &Call,
                CheckerContext &C) const;
  void evalFseek(const FnDescription *Desc, const CallEvent &Call,
                 CheckerContext &C) const;

  void preDefault(const FnDescription *Desc, const CallEvent &Call,
                  CheckerContext &C) const;

  void evalClearerr(const FnDescription *Desc, const CallEvent &Call,
                    CheckerContext &C) const;

  void evalFeofFerror(const FnDescription *Desc, const CallEvent &Call,
                      CheckerContext &C,
                      const StreamErrorState &ErrorKind) const;

  void evalSetFeofFerror(const FnDescription *Desc, const CallEvent &Call,
                         CheckerContext &C,
                         const StreamErrorState &ErrorKind) const;

  /// Check that the stream (in StreamVal) is not NULL.
  /// If it can only be NULL a fatal error is emitted and nullptr returned.
  /// Otherwise the return value is a new state where the stream is constrained
  /// to be non-null.
  ProgramStateRef ensureStreamNonNull(SVal StreamVal, CheckerContext &C,
                                      ProgramStateRef State) const;

  /// Check that the stream is the opened state.
  /// If the stream is known to be not opened an error is generated
  /// and nullptr returned, otherwise the original state is returned.
  ProgramStateRef ensureStreamOpened(SVal StreamVal, CheckerContext &C,
                                     ProgramStateRef State) const;

  /// Check that the stream has not an invalid ("indeterminate") file position,
  /// generate warning for it.
  /// (EOF is not an invalid position.)
  /// The returned state can be nullptr if a fatal error was generated.
  /// It can return non-null state if the stream has not an invalid position or
  /// there is execution path with non-invalid position.
  ProgramStateRef
  ensureNoFilePositionIndeterminate(SVal StreamVal, CheckerContext &C,
                                    ProgramStateRef State) const;

  /// Check the legality of the 'whence' argument of 'fseek'.
  /// Generate error and return nullptr if it is found to be illegal.
  /// Otherwise returns the state.
  /// (State is not changed here because the "whence" value is already known.)
  ProgramStateRef ensureFseekWhenceCorrect(SVal WhenceVal, CheckerContext &C,
                                           ProgramStateRef State) const;

  /// Generate warning about stream in EOF state.
  /// There will be always a state transition into the passed State,
  /// by the new non-fatal error node or (if failed) a normal transition,
  /// to ensure uniform handling.
  void reportFEofWarning(CheckerContext &C, ProgramStateRef State) const;

  /// Emit resource leak warnings for the given symbols.
  /// Createn a non-fatal error node for these, and returns it (if any warnings
  /// were generated). Return value is non-null.
  ExplodedNode *reportLeaks(const SmallVector<SymbolRef, 2> &LeakedSyms,
                            CheckerContext &C, ExplodedNode *Pred) const;

  /// Find the description data of the function called by a call event.
  /// Returns nullptr if no function is recognized.
  const FnDescription *lookupFn(const CallEvent &Call) const {
    // Recognize "global C functions" with only integral or pointer arguments
    // (and matching name) as stream functions.
    if (!Call.isGlobalCFunction())
      return nullptr;
    for (auto P : Call.parameters()) {
      QualType T = P->getType();
      if (!T->isIntegralOrEnumerationType() && !T->isPointerType())
        return nullptr;
    }

    return FnDescriptions.lookup(Call);
  }

  /// Generate a message for BugReporterVisitor if the stored symbol is
  /// marked as interesting by the actual bug report.
  struct NoteFn {
    const CheckerNameRef CheckerName;
    SymbolRef StreamSym;
    std::string Message;

    std::string operator()(PathSensitiveBugReport &BR) const {
      if (BR.isInteresting(StreamSym) &&
          CheckerName == BR.getBugType().getCheckerName())
        return Message;

      return "";
    }
  };

  const NoteTag *constructNoteTag(CheckerContext &C, SymbolRef StreamSym,
                                  const std::string &Message) const {
    return C.getNoteTag(NoteFn{getCheckerName(), StreamSym, Message});
  }

  /// Searches for the ExplodedNode where the file descriptor was acquired for
  /// StreamSym.
  static const ExplodedNode *getAcquisitionSite(const ExplodedNode *N,
                                                SymbolRef StreamSym,
                                                CheckerContext &C);
a105 34
inline void assertStreamStateOpened(const StreamState *SS) {
  assert(SS->isOpened() &&
         "Previous create of error node for non-opened stream failed?");
}

const ExplodedNode *StreamChecker::getAcquisitionSite(const ExplodedNode *N,
                                                      SymbolRef StreamSym,
                                                      CheckerContext &C) {
  ProgramStateRef State = N->getState();
  // When bug type is resource leak, exploded node N may not have state info
  // for leaked file descriptor, but predecessor should have it.
  if (!State->get<StreamMap>(StreamSym))
    N = N->getFirstPred();

  const ExplodedNode *Pred = N;
  while (N) {
    State = N->getState();
    if (!State->get<StreamMap>(StreamSym))
      return Pred;
    Pred = N;
    N = N->getFirstPred();
  }

  return nullptr;
}

void StreamChecker::checkPreCall(const CallEvent &Call,
                                 CheckerContext &C) const {
  const FnDescription *Desc = lookupFn(Call);
  if (!Desc || !Desc->PreFn)
    return;

  Desc->PreFn(this, Desc, Call, C);
}
d108 2
a109 4
  const FnDescription *Desc = lookupFn(Call);
  if (!Desc && TestMode)
    Desc = FnTestDescriptions.lookup(Call);
  if (!Desc || !Desc->EvalFn)
d112 1
a112 9
  Desc->EvalFn(this, Desc, Call, C);

  return C.isDifferent();
}

void StreamChecker::evalFopen(const FnDescription *Desc, const CallEvent &Call,
                              CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
d114 1
a114 1
    return;
d116 106
a221 5
  DefinedSVal RetVal = makeRetVal(C, CE);
  SymbolRef RetSym = RetVal.getAsSymbol();
  assert(RetSym && "RetVal must be a symbol here.");

  State = State->BindExpr(CE, C.getLocationContext(), RetVal);
d223 1
d226 9
a234 21
  ProgramStateRef StateNotNull, StateNull;
  std::tie(StateNotNull, StateNull) =
      C.getConstraintManager().assumeDual(State, RetVal);

  StateNotNull =
      StateNotNull->set<StreamMap>(RetSym, StreamState::getOpened(Desc));
  StateNull =
      StateNull->set<StreamMap>(RetSym, StreamState::getOpenFailed(Desc));

  C.addTransition(StateNotNull,
                  constructNoteTag(C, RetSym, "Stream opened here"));
  C.addTransition(StateNull);
}

void StreamChecker::preFreopen(const FnDescription *Desc, const CallEvent &Call,
                               CheckerContext &C) const {
  // Do not allow NULL as passed stream pointer but allow a closed stream.
  ProgramStateRef State = C.getState();
  State = ensureStreamNonNull(getStreamArg(Desc, Call), C, State);
  if (!State)
    return;
d236 3
a238 1
  C.addTransition(State);
d241 4
a244 64
void StreamChecker::evalFreopen(const FnDescription *Desc,
                                const CallEvent &Call,
                                CheckerContext &C) const {
  ProgramStateRef State = C.getState();

  auto *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
    return;

  Optional<DefinedSVal> StreamVal =
      getStreamArg(Desc, Call).getAs<DefinedSVal>();
  if (!StreamVal)
    return;

  SymbolRef StreamSym = StreamVal->getAsSymbol();
  // Do not care about concrete values for stream ("(FILE *)0x12345"?).
  // FIXME: Can be stdin, stdout, stderr such values?
  if (!StreamSym)
    return;

  // Do not handle untracked stream. It is probably escaped.
  if (!State->get<StreamMap>(StreamSym))
    return;

  // Generate state for non-failed case.
  // Return value is the passed stream pointer.
  // According to the documentations, the stream is closed first
  // but any close error is ignored. The state changes to (or remains) opened.
  ProgramStateRef StateRetNotNull =
      State->BindExpr(CE, C.getLocationContext(), *StreamVal);
  // Generate state for NULL return value.
  // Stream switches to OpenFailed state.
  ProgramStateRef StateRetNull = State->BindExpr(CE, C.getLocationContext(),
                                                 C.getSValBuilder().makeNull());

  StateRetNotNull =
      StateRetNotNull->set<StreamMap>(StreamSym, StreamState::getOpened(Desc));
  StateRetNull =
      StateRetNull->set<StreamMap>(StreamSym, StreamState::getOpenFailed(Desc));

  C.addTransition(StateRetNotNull,
                  constructNoteTag(C, StreamSym, "Stream reopened here"));
  C.addTransition(StateRetNull);
}

void StreamChecker::evalFclose(const FnDescription *Desc, const CallEvent &Call,
                               CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SymbolRef Sym = getStreamArg(Desc, Call).getAsSymbol();
  if (!Sym)
    return;

  const StreamState *SS = State->get<StreamMap>(Sym);
  if (!SS)
    return;

  assertStreamStateOpened(SS);

  // Close the File Descriptor.
  // Regardless if the close fails or not, stream becomes "closed"
  // and can not be used any more.
  State = State->set<StreamMap>(Sym, StreamState::getClosed(Desc));

  C.addTransition(State);
d247 3
a249 6
void StreamChecker::preFread(const FnDescription *Desc, const CallEvent &Call,
                             CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SVal StreamVal = getStreamArg(Desc, Call);
  State = ensureStreamNonNull(StreamVal, C, State);
  if (!State)
a250 15
  State = ensureStreamOpened(StreamVal, C, State);
  if (!State)
    return;
  State = ensureNoFilePositionIndeterminate(StreamVal, C, State);
  if (!State)
    return;

  SymbolRef Sym = StreamVal.getAsSymbol();
  if (Sym && State->get<StreamMap>(Sym)) {
    const StreamState *SS = State->get<StreamMap>(Sym);
    if (SS->ErrorState & ErrorFEof)
      reportFEofWarning(C, State);
  } else {
    C.addTransition(State);
  }
d253 3
a255 12
void StreamChecker::preFwrite(const FnDescription *Desc, const CallEvent &Call,
                              CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SVal StreamVal = getStreamArg(Desc, Call);
  State = ensureStreamNonNull(StreamVal, C, State);
  if (!State)
    return;
  State = ensureStreamOpened(StreamVal, C, State);
  if (!State)
    return;
  State = ensureNoFilePositionIndeterminate(StreamVal, C, State);
  if (!State)
a256 2

  C.addTransition(State);
d259 3
a261 6
void StreamChecker::evalFreadFwrite(const FnDescription *Desc,
                                    const CallEvent &Call, CheckerContext &C,
                                    bool IsFread) const {
  ProgramStateRef State = C.getState();
  SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
  if (!StreamSym)
d263 3
d267 1
a267 2
  const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
d270 2
a271 5
  Optional<NonLoc> SizeVal = Call.getArgSVal(1).getAs<NonLoc>();
  if (!SizeVal)
    return;
  Optional<NonLoc> NMembVal = Call.getArgSVal(2).getAs<NonLoc>();
  if (!NMembVal)
d274 8
a281 19
  const StreamState *SS = State->get<StreamMap>(StreamSym);
  if (!SS)
    return;

  assertStreamStateOpened(SS);

  // C'99 standard, §7.19.8.1.3, the return value of fread:
  // The fread function returns the number of elements successfully read, which
  // may be less than nmemb if a read error or end-of-file is encountered. If
  // size or nmemb is zero, fread returns zero and the contents of the array and
  // the state of the stream remain unchanged.

  if (State->isNull(*SizeVal).isConstrainedTrue() ||
      State->isNull(*NMembVal).isConstrainedTrue()) {
    // This is the "size or nmemb is zero" case.
    // Just return 0, do nothing more (not clear the error flags).
    State = bindInt(0, State, C, CE);
    C.addTransition(State);
    return;
d283 1
d285 3
a287 27
  // Generate a transition for the success state.
  // If we know the state to be FEOF at fread, do not add a success state.
  if (!IsFread || (SS->ErrorState != ErrorFEof)) {
    ProgramStateRef StateNotFailed =
        State->BindExpr(CE, C.getLocationContext(), *NMembVal);
    if (StateNotFailed) {
      StateNotFailed = StateNotFailed->set<StreamMap>(
          StreamSym, StreamState::getOpened(Desc));
      C.addTransition(StateNotFailed);
    }
  }

  // Add transition for the failed state.
  Optional<NonLoc> RetVal = makeRetVal(C, CE).castAs<NonLoc>();
  assert(RetVal && "Value should be NonLoc.");
  ProgramStateRef StateFailed =
      State->BindExpr(CE, C.getLocationContext(), *RetVal);
  if (!StateFailed)
    return;
  auto Cond = C.getSValBuilder()
                  .evalBinOpNN(State, BO_LT, *RetVal, *NMembVal,
                               C.getASTContext().IntTy)
                  .getAs<DefinedOrUnknownSVal>();
  if (!Cond)
    return;
  StateFailed = StateFailed->assume(*Cond, true);
  if (!StateFailed)
d289 1
d291 3
a293 24
  StreamErrorState NewES;
  if (IsFread)
    NewES = (SS->ErrorState == ErrorFEof) ? ErrorFEof : ErrorFEof | ErrorFError;
  else
    NewES = ErrorFError;
  // If a (non-EOF) error occurs, the resulting value of the file position
  // indicator for the stream is indeterminate.
  StreamState NewState = StreamState::getOpened(Desc, NewES, !NewES.isFEof());
  StateFailed = StateFailed->set<StreamMap>(StreamSym, NewState);
  C.addTransition(StateFailed);
}

void StreamChecker::preFseek(const FnDescription *Desc, const CallEvent &Call,
                             CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SVal StreamVal = getStreamArg(Desc, Call);
  State = ensureStreamNonNull(StreamVal, C, State);
  if (!State)
    return;
  State = ensureStreamOpened(StreamVal, C, State);
  if (!State)
    return;
  State = ensureFseekWhenceCorrect(Call.getArgSVal(2), C, State);
  if (!State)
a294 2

  C.addTransition(State);
d297 3
a299 5
void StreamChecker::evalFseek(const FnDescription *Desc, const CallEvent &Call,
                              CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
  if (!StreamSym)
d301 1
d303 3
a305 2
  const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
d307 1
d309 3
a311 2
  // Ignore the call if the stream is not tracked.
  if (!State->get<StreamMap>(StreamSym))
d313 1
d315 3
a317 36
  DefinedSVal RetVal = makeRetVal(C, CE);

  // Make expression result.
  State = State->BindExpr(CE, C.getLocationContext(), RetVal);

  // Bifurcate the state into failed and non-failed.
  // Return zero on success, nonzero on error.
  ProgramStateRef StateNotFailed, StateFailed;
  std::tie(StateFailed, StateNotFailed) =
      C.getConstraintManager().assumeDual(State, RetVal);

  // Reset the state to opened with no error.
  StateNotFailed =
      StateNotFailed->set<StreamMap>(StreamSym, StreamState::getOpened(Desc));
  // We get error.
  // It is possible that fseek fails but sets none of the error flags.
  // If fseek failed, assume that the file position becomes indeterminate in any
  // case.
  StateFailed = StateFailed->set<StreamMap>(
      StreamSym,
      StreamState::getOpened(Desc, ErrorNone | ErrorFEof | ErrorFError, true));

  C.addTransition(StateNotFailed);
  C.addTransition(StateFailed);
}

void StreamChecker::evalClearerr(const FnDescription *Desc,
                                 const CallEvent &Call,
                                 CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
  if (!StreamSym)
    return;

  const StreamState *SS = State->get<StreamMap>(StreamSym);
  if (!SS)
a318 8

  assertStreamStateOpened(SS);

  // FilePositionIndeterminate is not cleared.
  State = State->set<StreamMap>(
      StreamSym,
      StreamState::getOpened(Desc, ErrorNone, SS->FilePositionIndeterminate));
  C.addTransition(State);
d321 3
a323 14
void StreamChecker::evalFeofFerror(const FnDescription *Desc,
                                   const CallEvent &Call, CheckerContext &C,
                                   const StreamErrorState &ErrorKind) const {
  ProgramStateRef State = C.getState();
  SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
  if (!StreamSym)
    return;

  const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
    return;

  const StreamState *SS = State->get<StreamMap>(StreamSym);
  if (!SS)
a324 23

  assertStreamStateOpened(SS);

  if (SS->ErrorState & ErrorKind) {
    // Execution path with error of ErrorKind.
    // Function returns true.
    // From now on it is the only one error state.
    ProgramStateRef TrueState = bindAndAssumeTrue(State, C, CE);
    C.addTransition(TrueState->set<StreamMap>(
        StreamSym, StreamState::getOpened(Desc, ErrorKind,
                                          SS->FilePositionIndeterminate &&
                                              !ErrorKind.isFEof())));
  }
  if (StreamErrorState NewES = SS->ErrorState & (~ErrorKind)) {
    // Execution path(s) with ErrorKind not set.
    // Function returns false.
    // New error state is everything before minus ErrorKind.
    ProgramStateRef FalseState = bindInt(0, State, C, CE);
    C.addTransition(FalseState->set<StreamMap>(
        StreamSym,
        StreamState::getOpened(
            Desc, NewES, SS->FilePositionIndeterminate && !NewES.isFEof())));
  }
d327 3
a329 9
void StreamChecker::preDefault(const FnDescription *Desc, const CallEvent &Call,
                               CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SVal StreamVal = getStreamArg(Desc, Call);
  State = ensureStreamNonNull(StreamVal, C, State);
  if (!State)
    return;
  State = ensureStreamOpened(StreamVal, C, State);
  if (!State)
a330 2

  C.addTransition(State);
d333 5
a337 19
void StreamChecker::evalSetFeofFerror(const FnDescription *Desc,
                                      const CallEvent &Call, CheckerContext &C,
                                      const StreamErrorState &ErrorKind) const {
  ProgramStateRef State = C.getState();
  SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
  assert(StreamSym && "Operation not permitted on non-symbolic stream value.");
  const StreamState *SS = State->get<StreamMap>(StreamSym);
  assert(SS && "Stream should be tracked by the checker.");
  State = State->set<StreamMap>(
      StreamSym, StreamState::getOpened(SS->LastOperation, ErrorKind));
  C.addTransition(State);
}

ProgramStateRef
StreamChecker::ensureStreamNonNull(SVal StreamVal, CheckerContext &C,
                                   ProgramStateRef State) const {
  auto Stream = StreamVal.getAs<DefinedSVal>();
  if (!Stream)
    return State;
d340 2
d343 5
a347 5
  ProgramStateRef StateNotNull, StateNull;
  std::tie(StateNotNull, StateNull) = CM.assumeDual(C.getState(), *Stream);

  if (!StateNotNull && StateNull) {
    if (ExplodedNode *N = C.generateErrorNode(StateNull)) {
d349 1
a349 1
          BT_FileNull, "Stream pointer might be NULL.", N));
d353 1
a353 2

  return StateNotNull;
d356 4
a359 4
ProgramStateRef StreamChecker::ensureStreamOpened(SVal StreamVal,
                                                  CheckerContext &C,
                                                  ProgramStateRef State) const {
  SymbolRef Sym = StreamVal.getAsSymbol();
d361 3
a363 1
    return State;
d365 1
a365 1
  const StreamState *SS = State->get<StreamMap>(Sym);
d367 1
a367 1
    return State;
d369 2
a371 2
    // Using a stream pointer after 'fclose' causes undefined behavior
    // according to cppreference.com .
d374 4
d379 1
a379 3
          BT_UseAfterClose,
          "Stream might be already closed. Causes undefined behaviour.", N));
      return nullptr;
a380 64

    return State;
  }

  if (SS->isOpenFailed()) {
    // Using a stream that has failed to open is likely to cause problems.
    // This should usually not occur because stream pointer is NULL.
    // But freopen can cause a state when stream pointer remains non-null but
    // failed to open.
    ExplodedNode *N = C.generateErrorNode();
    if (N) {
      C.emitReport(std::make_unique<PathSensitiveBugReport>(
          BT_UseAfterOpenFailed,
          "Stream might be invalid after "
          "(re-)opening it has failed. "
          "Can cause undefined behaviour.",
          N));
      return nullptr;
    }
    return State;
  }

  return State;
}

ProgramStateRef StreamChecker::ensureNoFilePositionIndeterminate(
    SVal StreamVal, CheckerContext &C, ProgramStateRef State) const {
  static const char *BugMessage =
      "File position of the stream might be 'indeterminate' "
      "after a failed operation. "
      "Can cause undefined behavior.";

  SymbolRef Sym = StreamVal.getAsSymbol();
  if (!Sym)
    return State;

  const StreamState *SS = State->get<StreamMap>(Sym);
  if (!SS)
    return State;

  assert(SS->isOpened() && "First ensure that stream is opened.");

  if (SS->FilePositionIndeterminate) {
    if (SS->ErrorState & ErrorFEof) {
      // The error is unknown but may be FEOF.
      // Continue analysis with the FEOF error state.
      // Report warning because the other possible error states.
      ExplodedNode *N = C.generateNonFatalErrorNode(State);
      if (!N)
        return nullptr;

      C.emitReport(std::make_unique<PathSensitiveBugReport>(
          BT_IndeterminatePosition, BugMessage, N));
      return State->set<StreamMap>(
          Sym, StreamState::getOpened(SS->LastOperation, ErrorFEof, false));
    }

    // Known or unknown error state without FEOF possible.
    // Stop analysis, report error.
    ExplodedNode *N = C.generateErrorNode(State);
    if (N)
      C.emitReport(std::make_unique<PathSensitiveBugReport>(
          BT_IndeterminatePosition, BugMessage, N));

d384 2
a385 76
  return State;
}

ProgramStateRef
StreamChecker::ensureFseekWhenceCorrect(SVal WhenceVal, CheckerContext &C,
                                        ProgramStateRef State) const {
  Optional<nonloc::ConcreteInt> CI = WhenceVal.getAs<nonloc::ConcreteInt>();
  if (!CI)
    return State;

  int64_t X = CI->getValue().getSExtValue();
  if (X >= 0 && X <= 2)
    return State;

  if (ExplodedNode *N = C.generateNonFatalErrorNode(State)) {
    C.emitReport(std::make_unique<PathSensitiveBugReport>(
        BT_IllegalWhence,
        "The whence argument to fseek() should be "
        "SEEK_SET, SEEK_END, or SEEK_CUR.",
        N));
    return nullptr;
  }

  return State;
}

void StreamChecker::reportFEofWarning(CheckerContext &C,
                                      ProgramStateRef State) const {
  if (ExplodedNode *N = C.generateNonFatalErrorNode(State)) {
    C.emitReport(std::make_unique<PathSensitiveBugReport>(
        BT_StreamEof,
        "Read function called when stream is in EOF state. "
        "Function has no effect.",
        N));
    return;
  }
  C.addTransition(State);
}

ExplodedNode *
StreamChecker::reportLeaks(const SmallVector<SymbolRef, 2> &LeakedSyms,
                           CheckerContext &C, ExplodedNode *Pred) const {
  ExplodedNode *Err = C.generateNonFatalErrorNode(C.getState(), Pred);
  if (!Err)
    return Pred;

  for (SymbolRef LeakSym : LeakedSyms) {
    // Resource leaks can result in multiple warning that describe the same kind
    // of programming error:
    //  void f() {
    //    FILE *F = fopen("a.txt");
    //    if (rand()) // state split
    //      return; // warning
    //  } // warning
    // While this isn't necessarily true (leaking the same stream could result
    // from a different kinds of errors), the reduction in redundant reports
    // makes this a worthwhile heuristic.
    // FIXME: Add a checker option to turn this uniqueing feature off.
    const ExplodedNode *StreamOpenNode = getAcquisitionSite(Err, LeakSym, C);
    assert(StreamOpenNode && "Could not find place of stream opening.");
    PathDiagnosticLocation LocUsedForUniqueing =
        PathDiagnosticLocation::createBegin(
            StreamOpenNode->getStmtForDiagnostics(), C.getSourceManager(),
            StreamOpenNode->getLocationContext());

    std::unique_ptr<PathSensitiveBugReport> R =
        std::make_unique<PathSensitiveBugReport>(
            BT_ResourceLeak,
            "Opened stream never closed. Potential resource leak.", Err,
            LocUsedForUniqueing,
            StreamOpenNode->getLocationContext()->getDecl());
    R->markInteresting(LeakSym);
    C.emitReport(std::move(R));
  }

  return Err;
d390 1
a390 1
  ProgramStateRef State = C.getState();
d392 3
a394 4
  llvm::SmallVector<SymbolRef, 2> LeakedSyms;

  const StreamMapTy &Map = State->get<StreamMap>();
  for (const auto &I : Map) {
d397 1
a397 1
    if (!SymReaper.isDead(Sym))
a398 4
    if (SS.isOpened())
      LeakedSyms.push_back(Sym);
    State = State->remove<StreamMap>(Sym);
  }
d400 3
a402 3
  ExplodedNode *N = C.getPredecessor();
  if (!LeakedSyms.empty())
    N = reportLeaks(LeakedSyms, C, N);
d404 6
a409 21
  C.addTransition(State, N);
}

ProgramStateRef StreamChecker::checkPointerEscape(
    ProgramStateRef State, const InvalidatedSymbols &Escaped,
    const CallEvent *Call, PointerEscapeKind Kind) const {
  // Check for file-handling system call that is not handled by the checker.
  // FIXME: The checker should be updated to handle all system calls that take
  // 'FILE*' argument. These are now ignored.
  if (Kind == PSK_DirectEscapeOnCall && Call->isInSystemHeader())
    return State;

  for (SymbolRef Sym : Escaped) {
    // The symbol escaped.
    // From now the stream can be manipulated in unknown way to the checker,
    // it is not possible to handle it any more.
    // Optimistically, assume that the corresponding file handle will be closed
    // somewhere else.
    // Remove symbol from state so the following stream calls on this symbol are
    // not handled by the checker.
    State = State->remove<StreamMap>(Sym);
a410 9
  return State;
}

void ento::registerStreamChecker(CheckerManager &Mgr) {
  Mgr.registerChecker<StreamChecker>();
}

bool ento::shouldRegisterStreamChecker(const CheckerManager &Mgr) {
  return true;
d413 2
a414 3
void ento::registerStreamTesterChecker(CheckerManager &Mgr) {
  auto *Checker = Mgr.getChecker<StreamChecker>();
  Checker->TestMode = true;
d417 1
a417 1
bool ento::shouldRegisterStreamTesterChecker(const CheckerManager &Mgr) {
@


1.1.1.2
log
@Import clang 249b40b558955afe5ac2b549edcf2d7f859c8cc9.
@
text
@a21 1
#include <functional>
a24 1
using namespace std::placeholders;
d28 3
a30 1
struct FnDescription;
d32 1
a32 13
/// State of the stream error flags.
/// Sometimes it is not known to the checker what error flags are set.
/// This is indicated by setting more than one flag to true.
/// This is an optimization to avoid state splits.
/// A stream can either be in FEOF or FERROR but not both at the same time.
/// Multiple flags are set to handle the corresponding states together.
struct StreamErrorState {
  /// The stream can be in state where none of the error flags set.
  bool NoError = true;
  /// The stream can be in state where the EOF indicator is set.
  bool FEof = false;
  /// The stream can be in state where the error indicator is set.
  bool FError = false;
d34 4
a37 3
  bool isNoError() const { return NoError && !FEof && !FError; }
  bool isFEof() const { return !NoError && FEof && !FError; }
  bool isFError() const { return !NoError && !FEof && FError; }
d39 2
a40 2
  bool operator==(const StreamErrorState &ES) const {
    return NoError == ES.NoError && FEof == ES.FEof && FError == ES.FError;
d43 4
a46 4
  bool operator!=(const StreamErrorState &ES) const { return !(*this == ES); }

  StreamErrorState operator|(const StreamErrorState &E) const {
    return {NoError || E.NoError, FEof || E.FEof, FError || E.FError};
d48 2
a49 3

  StreamErrorState operator&(const StreamErrorState &E) const {
    return {NoError && E.NoError, FEof && E.FEof, FError && E.FError};
a51 5
  StreamErrorState operator~() const { return {!NoError, !FEof, !FError}; }

  /// Returns if the StreamErrorState is a valid object.
  operator bool() const { return NoError || FEof || FError; }

d53 2
a54 3
    ID.AddBoolean(NoError);
    ID.AddBoolean(FEof);
    ID.AddBoolean(FError);
d58 8
a65 3
const StreamErrorState ErrorNone{true, false, false};
const StreamErrorState ErrorFEof{false, true, false};
const StreamErrorState ErrorFError{false, false, true};
d67 7
a73 89
/// Full state information about a stream pointer.
struct StreamState {
  /// The last file operation called in the stream.
  const FnDescription *LastOperation;

  /// State of a stream symbol.
  /// FIXME: We need maybe an "escaped" state later.
  enum KindTy {
    Opened, /// Stream is opened.
    Closed, /// Closed stream (an invalid stream pointer after it was closed).
    OpenFailed /// The last open operation has failed.
  } State;

  /// State of the error flags.
  /// Ignored in non-opened stream state but must be NoError.
  StreamErrorState const ErrorState;

  /// Indicate if the file has an "indeterminate file position indicator".
  /// This can be set at a failing read or write or seek operation.
  /// If it is set no more read or write is allowed.
  /// This value is not dependent on the stream error flags:
  /// The error flag may be cleared with `clearerr` but the file position
  /// remains still indeterminate.
  /// This value applies to all error states in ErrorState except FEOF.
  /// An EOF+indeterminate state is the same as EOF state.
  bool const FilePositionIndeterminate = false;

  StreamState(const FnDescription *L, KindTy S, const StreamErrorState &ES,
              bool IsFilePositionIndeterminate)
      : LastOperation(L), State(S), ErrorState(ES),
        FilePositionIndeterminate(IsFilePositionIndeterminate) {
    assert((!ES.isFEof() || !IsFilePositionIndeterminate) &&
           "FilePositionIndeterminate should be false in FEof case.");
    assert((State == Opened || ErrorState.isNoError()) &&
           "ErrorState should be None in non-opened stream state.");
  }

  bool isOpened() const { return State == Opened; }
  bool isClosed() const { return State == Closed; }
  bool isOpenFailed() const { return State == OpenFailed; }

  bool operator==(const StreamState &X) const {
    // In not opened state error state should always NoError, so comparison
    // here is no problem.
    return LastOperation == X.LastOperation && State == X.State &&
           ErrorState == X.ErrorState &&
           FilePositionIndeterminate == X.FilePositionIndeterminate;
  }

  static StreamState getOpened(const FnDescription *L,
                               const StreamErrorState &ES = ErrorNone,
                               bool IsFilePositionIndeterminate = false) {
    return StreamState{L, Opened, ES, IsFilePositionIndeterminate};
  }
  static StreamState getClosed(const FnDescription *L) {
    return StreamState{L, Closed, {}, false};
  }
  static StreamState getOpenFailed(const FnDescription *L) {
    return StreamState{L, OpenFailed, {}, false};
  }

  void Profile(llvm::FoldingSetNodeID &ID) const {
    ID.AddPointer(LastOperation);
    ID.AddInteger(State);
    ID.AddInteger(ErrorState);
    ID.AddBoolean(FilePositionIndeterminate);
  }
};

class StreamChecker;
using FnCheck = std::function<void(const StreamChecker *, const FnDescription *,
                                   const CallEvent &, CheckerContext &)>;

using ArgNoTy = unsigned int;
static const ArgNoTy ArgNone = std::numeric_limits<ArgNoTy>::max();

struct FnDescription {
  FnCheck PreFn;
  FnCheck EvalFn;
  ArgNoTy StreamArgNo;
};

/// Get the value of the stream argument out of the passed call event.
/// The call should contain a function that is described by Desc.
SVal getStreamArg(const FnDescription *Desc, const CallEvent &Call) {
  assert(Desc && Desc->StreamArgNo != ArgNone &&
         "Try to get a non-existing stream argument.");
  return Call.getArgSVal(Desc->StreamArgNo);
}
a74 42
/// Create a conjured symbol return value for a call expression.
DefinedSVal makeRetVal(CheckerContext &C, const CallExpr *CE) {
  assert(CE && "Expecting a call expression.");

  const LocationContext *LCtx = C.getLocationContext();
  return C.getSValBuilder()
      .conjureSymbolVal(nullptr, CE, LCtx, C.blockCount())
      .castAs<DefinedSVal>();
}

ProgramStateRef bindAndAssumeTrue(ProgramStateRef State, CheckerContext &C,
                                  const CallExpr *CE) {
  DefinedSVal RetVal = makeRetVal(C, CE);
  State = State->BindExpr(CE, C.getLocationContext(), RetVal);
  State = State->assume(RetVal, true);
  assert(State && "Assumption on new value should not fail.");
  return State;
}

ProgramStateRef bindInt(uint64_t Value, ProgramStateRef State,
                        CheckerContext &C, const CallExpr *CE) {
  State = State->BindExpr(CE, C.getLocationContext(),
                          C.getSValBuilder().makeIntVal(Value, false));
  return State;
}

class StreamChecker : public Checker<check::PreCall, eval::Call,
                                     check::DeadSymbols, check::PointerEscape> {
  BugType BT_FileNull{this, "NULL stream pointer", "Stream handling error"};
  BugType BT_UseAfterClose{this, "Closed stream", "Stream handling error"};
  BugType BT_UseAfterOpenFailed{this, "Invalid stream",
                                "Stream handling error"};
  BugType BT_IndeterminatePosition{this, "Invalid stream state",
                                   "Stream handling error"};
  BugType BT_IllegalWhence{this, "Illegal whence argument",
                           "Stream handling error"};
  BugType BT_StreamEof{this, "Stream already in EOF", "Stream handling error"};
  BugType BT_ResourceLeak{this, "Resource leak", "Stream handling error",
                          /*SuppressOnSink =*/true};

public:
  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
a76 7
  ProgramStateRef checkPointerEscape(ProgramStateRef State,
                                     const InvalidatedSymbols &Escaped,
                                     const CallEvent *Call,
                                     PointerEscapeKind Kind) const;

  /// If true, evaluate special testing stream functions.
  bool TestMode = false;
d79 21
a99 166
  CallDescriptionMap<FnDescription> FnDescriptions = {
      {{"fopen"}, {nullptr, &StreamChecker::evalFopen, ArgNone}},
      {{"freopen", 3},
       {&StreamChecker::preFreopen, &StreamChecker::evalFreopen, 2}},
      {{"tmpfile"}, {nullptr, &StreamChecker::evalFopen, ArgNone}},
      {{"fclose", 1},
       {&StreamChecker::preDefault, &StreamChecker::evalFclose, 0}},
      {{"fread", 4},
       {&StreamChecker::preFread,
        std::bind(&StreamChecker::evalFreadFwrite, _1, _2, _3, _4, true), 3}},
      {{"fwrite", 4},
       {&StreamChecker::preFwrite,
        std::bind(&StreamChecker::evalFreadFwrite, _1, _2, _3, _4, false), 3}},
      {{"fseek", 3}, {&StreamChecker::preFseek, &StreamChecker::evalFseek, 0}},
      {{"ftell", 1}, {&StreamChecker::preDefault, nullptr, 0}},
      {{"rewind", 1}, {&StreamChecker::preDefault, nullptr, 0}},
      {{"fgetpos", 2}, {&StreamChecker::preDefault, nullptr, 0}},
      {{"fsetpos", 2}, {&StreamChecker::preDefault, nullptr, 0}},
      {{"clearerr", 1},
       {&StreamChecker::preDefault, &StreamChecker::evalClearerr, 0}},
      {{"feof", 1},
       {&StreamChecker::preDefault,
        std::bind(&StreamChecker::evalFeofFerror, _1, _2, _3, _4, ErrorFEof),
        0}},
      {{"ferror", 1},
       {&StreamChecker::preDefault,
        std::bind(&StreamChecker::evalFeofFerror, _1, _2, _3, _4, ErrorFError),
        0}},
      {{"fileno", 1}, {&StreamChecker::preDefault, nullptr, 0}},
  };

  CallDescriptionMap<FnDescription> FnTestDescriptions = {
      {{"StreamTesterChecker_make_feof_stream", 1},
       {nullptr,
        std::bind(&StreamChecker::evalSetFeofFerror, _1, _2, _3, _4, ErrorFEof),
        0}},
      {{"StreamTesterChecker_make_ferror_stream", 1},
       {nullptr,
        std::bind(&StreamChecker::evalSetFeofFerror, _1, _2, _3, _4,
                  ErrorFError),
        0}},
  };

  void evalFopen(const FnDescription *Desc, const CallEvent &Call,
                 CheckerContext &C) const;

  void preFreopen(const FnDescription *Desc, const CallEvent &Call,
                  CheckerContext &C) const;
  void evalFreopen(const FnDescription *Desc, const CallEvent &Call,
                   CheckerContext &C) const;

  void evalFclose(const FnDescription *Desc, const CallEvent &Call,
                  CheckerContext &C) const;

  void preFread(const FnDescription *Desc, const CallEvent &Call,
                CheckerContext &C) const;

  void preFwrite(const FnDescription *Desc, const CallEvent &Call,
                 CheckerContext &C) const;

  void evalFreadFwrite(const FnDescription *Desc, const CallEvent &Call,
                       CheckerContext &C, bool IsFread) const;

  void preFseek(const FnDescription *Desc, const CallEvent &Call,
                CheckerContext &C) const;
  void evalFseek(const FnDescription *Desc, const CallEvent &Call,
                 CheckerContext &C) const;

  void preDefault(const FnDescription *Desc, const CallEvent &Call,
                  CheckerContext &C) const;

  void evalClearerr(const FnDescription *Desc, const CallEvent &Call,
                    CheckerContext &C) const;

  void evalFeofFerror(const FnDescription *Desc, const CallEvent &Call,
                      CheckerContext &C,
                      const StreamErrorState &ErrorKind) const;

  void evalSetFeofFerror(const FnDescription *Desc, const CallEvent &Call,
                         CheckerContext &C,
                         const StreamErrorState &ErrorKind) const;

  /// Check that the stream (in StreamVal) is not NULL.
  /// If it can only be NULL a fatal error is emitted and nullptr returned.
  /// Otherwise the return value is a new state where the stream is constrained
  /// to be non-null.
  ProgramStateRef ensureStreamNonNull(SVal StreamVal, CheckerContext &C,
                                      ProgramStateRef State) const;

  /// Check that the stream is the opened state.
  /// If the stream is known to be not opened an error is generated
  /// and nullptr returned, otherwise the original state is returned.
  ProgramStateRef ensureStreamOpened(SVal StreamVal, CheckerContext &C,
                                     ProgramStateRef State) const;

  /// Check that the stream has not an invalid ("indeterminate") file position,
  /// generate warning for it.
  /// (EOF is not an invalid position.)
  /// The returned state can be nullptr if a fatal error was generated.
  /// It can return non-null state if the stream has not an invalid position or
  /// there is execution path with non-invalid position.
  ProgramStateRef
  ensureNoFilePositionIndeterminate(SVal StreamVal, CheckerContext &C,
                                    ProgramStateRef State) const;

  /// Check the legality of the 'whence' argument of 'fseek'.
  /// Generate error and return nullptr if it is found to be illegal.
  /// Otherwise returns the state.
  /// (State is not changed here because the "whence" value is already known.)
  ProgramStateRef ensureFseekWhenceCorrect(SVal WhenceVal, CheckerContext &C,
                                           ProgramStateRef State) const;

  /// Generate warning about stream in EOF state.
  /// There will be always a state transition into the passed State,
  /// by the new non-fatal error node or (if failed) a normal transition,
  /// to ensure uniform handling.
  void reportFEofWarning(CheckerContext &C, ProgramStateRef State) const;

  /// Emit resource leak warnings for the given symbols.
  /// Createn a non-fatal error node for these, and returns it (if any warnings
  /// were generated). Return value is non-null.
  ExplodedNode *reportLeaks(const SmallVector<SymbolRef, 2> &LeakedSyms,
                            CheckerContext &C, ExplodedNode *Pred) const;

  /// Find the description data of the function called by a call event.
  /// Returns nullptr if no function is recognized.
  const FnDescription *lookupFn(const CallEvent &Call) const {
    // Recognize "global C functions" with only integral or pointer arguments
    // (and matching name) as stream functions.
    if (!Call.isGlobalCFunction())
      return nullptr;
    for (auto P : Call.parameters()) {
      QualType T = P->getType();
      if (!T->isIntegralOrEnumerationType() && !T->isPointerType())
        return nullptr;
    }

    return FnDescriptions.lookup(Call);
  }

  /// Generate a message for BugReporterVisitor if the stored symbol is
  /// marked as interesting by the actual bug report.
  struct NoteFn {
    const CheckerNameRef CheckerName;
    SymbolRef StreamSym;
    std::string Message;

    std::string operator()(PathSensitiveBugReport &BR) const {
      if (BR.isInteresting(StreamSym) &&
          CheckerName == BR.getBugType().getCheckerName())
        return Message;

      return "";
    }
  };

  const NoteTag *constructNoteTag(CheckerContext &C, SymbolRef StreamSym,
                                  const std::string &Message) const {
    return C.getNoteTag(NoteFn{getCheckerName(), StreamSym, Message});
  }

  /// Searches for the ExplodedNode where the file descriptor was acquired for
  /// StreamSym.
  static const ExplodedNode *getAcquisitionSite(const ExplodedNode *N,
                                                SymbolRef StreamSym,
                                                CheckerContext &C);
a105 34
inline void assertStreamStateOpened(const StreamState *SS) {
  assert(SS->isOpened() &&
         "Previous create of error node for non-opened stream failed?");
}

const ExplodedNode *StreamChecker::getAcquisitionSite(const ExplodedNode *N,
                                                      SymbolRef StreamSym,
                                                      CheckerContext &C) {
  ProgramStateRef State = N->getState();
  // When bug type is resource leak, exploded node N may not have state info
  // for leaked file descriptor, but predecessor should have it.
  if (!State->get<StreamMap>(StreamSym))
    N = N->getFirstPred();

  const ExplodedNode *Pred = N;
  while (N) {
    State = N->getState();
    if (!State->get<StreamMap>(StreamSym))
      return Pred;
    Pred = N;
    N = N->getFirstPred();
  }

  return nullptr;
}

void StreamChecker::checkPreCall(const CallEvent &Call,
                                 CheckerContext &C) const {
  const FnDescription *Desc = lookupFn(Call);
  if (!Desc || !Desc->PreFn)
    return;

  Desc->PreFn(this, Desc, Call, C);
}
d108 2
a109 4
  const FnDescription *Desc = lookupFn(Call);
  if (!Desc && TestMode)
    Desc = FnTestDescriptions.lookup(Call);
  if (!Desc || !Desc->EvalFn)
d112 1
a112 9
  Desc->EvalFn(this, Desc, Call, C);

  return C.isDifferent();
}

void StreamChecker::evalFopen(const FnDescription *Desc, const CallEvent &Call,
                              CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
d114 1
a114 1
    return;
d116 106
a221 5
  DefinedSVal RetVal = makeRetVal(C, CE);
  SymbolRef RetSym = RetVal.getAsSymbol();
  assert(RetSym && "RetVal must be a symbol here.");

  State = State->BindExpr(CE, C.getLocationContext(), RetVal);
d223 1
d226 9
a234 21
  ProgramStateRef StateNotNull, StateNull;
  std::tie(StateNotNull, StateNull) =
      C.getConstraintManager().assumeDual(State, RetVal);

  StateNotNull =
      StateNotNull->set<StreamMap>(RetSym, StreamState::getOpened(Desc));
  StateNull =
      StateNull->set<StreamMap>(RetSym, StreamState::getOpenFailed(Desc));

  C.addTransition(StateNotNull,
                  constructNoteTag(C, RetSym, "Stream opened here"));
  C.addTransition(StateNull);
}

void StreamChecker::preFreopen(const FnDescription *Desc, const CallEvent &Call,
                               CheckerContext &C) const {
  // Do not allow NULL as passed stream pointer but allow a closed stream.
  ProgramStateRef State = C.getState();
  State = ensureStreamNonNull(getStreamArg(Desc, Call), C, State);
  if (!State)
    return;
d236 3
a238 1
  C.addTransition(State);
d241 4
a244 64
void StreamChecker::evalFreopen(const FnDescription *Desc,
                                const CallEvent &Call,
                                CheckerContext &C) const {
  ProgramStateRef State = C.getState();

  auto *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
    return;

  Optional<DefinedSVal> StreamVal =
      getStreamArg(Desc, Call).getAs<DefinedSVal>();
  if (!StreamVal)
    return;

  SymbolRef StreamSym = StreamVal->getAsSymbol();
  // Do not care about concrete values for stream ("(FILE *)0x12345"?).
  // FIXME: Can be stdin, stdout, stderr such values?
  if (!StreamSym)
    return;

  // Do not handle untracked stream. It is probably escaped.
  if (!State->get<StreamMap>(StreamSym))
    return;

  // Generate state for non-failed case.
  // Return value is the passed stream pointer.
  // According to the documentations, the stream is closed first
  // but any close error is ignored. The state changes to (or remains) opened.
  ProgramStateRef StateRetNotNull =
      State->BindExpr(CE, C.getLocationContext(), *StreamVal);
  // Generate state for NULL return value.
  // Stream switches to OpenFailed state.
  ProgramStateRef StateRetNull = State->BindExpr(CE, C.getLocationContext(),
                                                 C.getSValBuilder().makeNull());

  StateRetNotNull =
      StateRetNotNull->set<StreamMap>(StreamSym, StreamState::getOpened(Desc));
  StateRetNull =
      StateRetNull->set<StreamMap>(StreamSym, StreamState::getOpenFailed(Desc));

  C.addTransition(StateRetNotNull,
                  constructNoteTag(C, StreamSym, "Stream reopened here"));
  C.addTransition(StateRetNull);
}

void StreamChecker::evalFclose(const FnDescription *Desc, const CallEvent &Call,
                               CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SymbolRef Sym = getStreamArg(Desc, Call).getAsSymbol();
  if (!Sym)
    return;

  const StreamState *SS = State->get<StreamMap>(Sym);
  if (!SS)
    return;

  assertStreamStateOpened(SS);

  // Close the File Descriptor.
  // Regardless if the close fails or not, stream becomes "closed"
  // and can not be used any more.
  State = State->set<StreamMap>(Sym, StreamState::getClosed(Desc));

  C.addTransition(State);
d247 3
a249 6
void StreamChecker::preFread(const FnDescription *Desc, const CallEvent &Call,
                             CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SVal StreamVal = getStreamArg(Desc, Call);
  State = ensureStreamNonNull(StreamVal, C, State);
  if (!State)
a250 15
  State = ensureStreamOpened(StreamVal, C, State);
  if (!State)
    return;
  State = ensureNoFilePositionIndeterminate(StreamVal, C, State);
  if (!State)
    return;

  SymbolRef Sym = StreamVal.getAsSymbol();
  if (Sym && State->get<StreamMap>(Sym)) {
    const StreamState *SS = State->get<StreamMap>(Sym);
    if (SS->ErrorState & ErrorFEof)
      reportFEofWarning(C, State);
  } else {
    C.addTransition(State);
  }
d253 3
a255 12
void StreamChecker::preFwrite(const FnDescription *Desc, const CallEvent &Call,
                              CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SVal StreamVal = getStreamArg(Desc, Call);
  State = ensureStreamNonNull(StreamVal, C, State);
  if (!State)
    return;
  State = ensureStreamOpened(StreamVal, C, State);
  if (!State)
    return;
  State = ensureNoFilePositionIndeterminate(StreamVal, C, State);
  if (!State)
a256 2

  C.addTransition(State);
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void StreamChecker::evalFreadFwrite(const FnDescription *Desc,
                                    const CallEvent &Call, CheckerContext &C,
                                    bool IsFread) const {
  ProgramStateRef State = C.getState();
  SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
  if (!StreamSym)
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a267 2
  const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
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  Optional<NonLoc> SizeVal = Call.getArgSVal(1).getAs<NonLoc>();
  if (!SizeVal)
    return;
  Optional<NonLoc> NMembVal = Call.getArgSVal(2).getAs<NonLoc>();
  if (!NMembVal)
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  const StreamState *SS = State->get<StreamMap>(StreamSym);
  if (!SS)
    return;

  assertStreamStateOpened(SS);

  // C'99 standard, §7.19.8.1.3, the return value of fread:
  // The fread function returns the number of elements successfully read, which
  // may be less than nmemb if a read error or end-of-file is encountered. If
  // size or nmemb is zero, fread returns zero and the contents of the array and
  // the state of the stream remain unchanged.

  if (State->isNull(*SizeVal).isConstrainedTrue() ||
      State->isNull(*NMembVal).isConstrainedTrue()) {
    // This is the "size or nmemb is zero" case.
    // Just return 0, do nothing more (not clear the error flags).
    State = bindInt(0, State, C, CE);
    C.addTransition(State);
    return;
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a287 27
  // Generate a transition for the success state.
  // If we know the state to be FEOF at fread, do not add a success state.
  if (!IsFread || (SS->ErrorState != ErrorFEof)) {
    ProgramStateRef StateNotFailed =
        State->BindExpr(CE, C.getLocationContext(), *NMembVal);
    if (StateNotFailed) {
      StateNotFailed = StateNotFailed->set<StreamMap>(
          StreamSym, StreamState::getOpened(Desc));
      C.addTransition(StateNotFailed);
    }
  }

  // Add transition for the failed state.
  Optional<NonLoc> RetVal = makeRetVal(C, CE).castAs<NonLoc>();
  assert(RetVal && "Value should be NonLoc.");
  ProgramStateRef StateFailed =
      State->BindExpr(CE, C.getLocationContext(), *RetVal);
  if (!StateFailed)
    return;
  auto Cond = C.getSValBuilder()
                  .evalBinOpNN(State, BO_LT, *RetVal, *NMembVal,
                               C.getASTContext().IntTy)
                  .getAs<DefinedOrUnknownSVal>();
  if (!Cond)
    return;
  StateFailed = StateFailed->assume(*Cond, true);
  if (!StateFailed)
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a293 24
  StreamErrorState NewES;
  if (IsFread)
    NewES = (SS->ErrorState == ErrorFEof) ? ErrorFEof : ErrorFEof | ErrorFError;
  else
    NewES = ErrorFError;
  // If a (non-EOF) error occurs, the resulting value of the file position
  // indicator for the stream is indeterminate.
  StreamState NewState = StreamState::getOpened(Desc, NewES, !NewES.isFEof());
  StateFailed = StateFailed->set<StreamMap>(StreamSym, NewState);
  C.addTransition(StateFailed);
}

void StreamChecker::preFseek(const FnDescription *Desc, const CallEvent &Call,
                             CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SVal StreamVal = getStreamArg(Desc, Call);
  State = ensureStreamNonNull(StreamVal, C, State);
  if (!State)
    return;
  State = ensureStreamOpened(StreamVal, C, State);
  if (!State)
    return;
  State = ensureFseekWhenceCorrect(Call.getArgSVal(2), C, State);
  if (!State)
a294 2

  C.addTransition(State);
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void StreamChecker::evalFseek(const FnDescription *Desc, const CallEvent &Call,
                              CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
  if (!StreamSym)
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  const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
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  // Ignore the call if the stream is not tracked.
  if (!State->get<StreamMap>(StreamSym))
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a317 36
  DefinedSVal RetVal = makeRetVal(C, CE);

  // Make expression result.
  State = State->BindExpr(CE, C.getLocationContext(), RetVal);

  // Bifurcate the state into failed and non-failed.
  // Return zero on success, nonzero on error.
  ProgramStateRef StateNotFailed, StateFailed;
  std::tie(StateFailed, StateNotFailed) =
      C.getConstraintManager().assumeDual(State, RetVal);

  // Reset the state to opened with no error.
  StateNotFailed =
      StateNotFailed->set<StreamMap>(StreamSym, StreamState::getOpened(Desc));
  // We get error.
  // It is possible that fseek fails but sets none of the error flags.
  // If fseek failed, assume that the file position becomes indeterminate in any
  // case.
  StateFailed = StateFailed->set<StreamMap>(
      StreamSym,
      StreamState::getOpened(Desc, ErrorNone | ErrorFEof | ErrorFError, true));

  C.addTransition(StateNotFailed);
  C.addTransition(StateFailed);
}

void StreamChecker::evalClearerr(const FnDescription *Desc,
                                 const CallEvent &Call,
                                 CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
  if (!StreamSym)
    return;

  const StreamState *SS = State->get<StreamMap>(StreamSym);
  if (!SS)
a318 8

  assertStreamStateOpened(SS);

  // FilePositionIndeterminate is not cleared.
  State = State->set<StreamMap>(
      StreamSym,
      StreamState::getOpened(Desc, ErrorNone, SS->FilePositionIndeterminate));
  C.addTransition(State);
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void StreamChecker::evalFeofFerror(const FnDescription *Desc,
                                   const CallEvent &Call, CheckerContext &C,
                                   const StreamErrorState &ErrorKind) const {
  ProgramStateRef State = C.getState();
  SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
  if (!StreamSym)
    return;

  const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
    return;

  const StreamState *SS = State->get<StreamMap>(StreamSym);
  if (!SS)
a324 23

  assertStreamStateOpened(SS);

  if (SS->ErrorState & ErrorKind) {
    // Execution path with error of ErrorKind.
    // Function returns true.
    // From now on it is the only one error state.
    ProgramStateRef TrueState = bindAndAssumeTrue(State, C, CE);
    C.addTransition(TrueState->set<StreamMap>(
        StreamSym, StreamState::getOpened(Desc, ErrorKind,
                                          SS->FilePositionIndeterminate &&
                                              !ErrorKind.isFEof())));
  }
  if (StreamErrorState NewES = SS->ErrorState & (~ErrorKind)) {
    // Execution path(s) with ErrorKind not set.
    // Function returns false.
    // New error state is everything before minus ErrorKind.
    ProgramStateRef FalseState = bindInt(0, State, C, CE);
    C.addTransition(FalseState->set<StreamMap>(
        StreamSym,
        StreamState::getOpened(
            Desc, NewES, SS->FilePositionIndeterminate && !NewES.isFEof())));
  }
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void StreamChecker::preDefault(const FnDescription *Desc, const CallEvent &Call,
                               CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SVal StreamVal = getStreamArg(Desc, Call);
  State = ensureStreamNonNull(StreamVal, C, State);
  if (!State)
    return;
  State = ensureStreamOpened(StreamVal, C, State);
  if (!State)
a330 2

  C.addTransition(State);
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void StreamChecker::evalSetFeofFerror(const FnDescription *Desc,
                                      const CallEvent &Call, CheckerContext &C,
                                      const StreamErrorState &ErrorKind) const {
  ProgramStateRef State = C.getState();
  SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
  assert(StreamSym && "Operation not permitted on non-symbolic stream value.");
  const StreamState *SS = State->get<StreamMap>(StreamSym);
  assert(SS && "Stream should be tracked by the checker.");
  State = State->set<StreamMap>(
      StreamSym, StreamState::getOpened(SS->LastOperation, ErrorKind));
  C.addTransition(State);
}

ProgramStateRef
StreamChecker::ensureStreamNonNull(SVal StreamVal, CheckerContext &C,
                                   ProgramStateRef State) const {
  auto Stream = StreamVal.getAs<DefinedSVal>();
  if (!Stream)
    return State;
d340 2
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a347 5
  ProgramStateRef StateNotNull, StateNull;
  std::tie(StateNotNull, StateNull) = CM.assumeDual(C.getState(), *Stream);

  if (!StateNotNull && StateNull) {
    if (ExplodedNode *N = C.generateErrorNode(StateNull)) {
d349 1
a349 1
          BT_FileNull, "Stream pointer might be NULL.", N));
d353 1
a353 2

  return StateNotNull;
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a359 4
ProgramStateRef StreamChecker::ensureStreamOpened(SVal StreamVal,
                                                  CheckerContext &C,
                                                  ProgramStateRef State) const {
  SymbolRef Sym = StreamVal.getAsSymbol();
d361 3
a363 1
    return State;
d365 1
a365 1
  const StreamState *SS = State->get<StreamMap>(Sym);
d367 1
a367 1
    return State;
d369 2
a371 2
    // Using a stream pointer after 'fclose' causes undefined behavior
    // according to cppreference.com .
d374 4
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a379 3
          BT_UseAfterClose,
          "Stream might be already closed. Causes undefined behaviour.", N));
      return nullptr;
a380 64

    return State;
  }

  if (SS->isOpenFailed()) {
    // Using a stream that has failed to open is likely to cause problems.
    // This should usually not occur because stream pointer is NULL.
    // But freopen can cause a state when stream pointer remains non-null but
    // failed to open.
    ExplodedNode *N = C.generateErrorNode();
    if (N) {
      C.emitReport(std::make_unique<PathSensitiveBugReport>(
          BT_UseAfterOpenFailed,
          "Stream might be invalid after "
          "(re-)opening it has failed. "
          "Can cause undefined behaviour.",
          N));
      return nullptr;
    }
    return State;
  }

  return State;
}

ProgramStateRef StreamChecker::ensureNoFilePositionIndeterminate(
    SVal StreamVal, CheckerContext &C, ProgramStateRef State) const {
  static const char *BugMessage =
      "File position of the stream might be 'indeterminate' "
      "after a failed operation. "
      "Can cause undefined behavior.";

  SymbolRef Sym = StreamVal.getAsSymbol();
  if (!Sym)
    return State;

  const StreamState *SS = State->get<StreamMap>(Sym);
  if (!SS)
    return State;

  assert(SS->isOpened() && "First ensure that stream is opened.");

  if (SS->FilePositionIndeterminate) {
    if (SS->ErrorState & ErrorFEof) {
      // The error is unknown but may be FEOF.
      // Continue analysis with the FEOF error state.
      // Report warning because the other possible error states.
      ExplodedNode *N = C.generateNonFatalErrorNode(State);
      if (!N)
        return nullptr;

      C.emitReport(std::make_unique<PathSensitiveBugReport>(
          BT_IndeterminatePosition, BugMessage, N));
      return State->set<StreamMap>(
          Sym, StreamState::getOpened(SS->LastOperation, ErrorFEof, false));
    }

    // Known or unknown error state without FEOF possible.
    // Stop analysis, report error.
    ExplodedNode *N = C.generateErrorNode(State);
    if (N)
      C.emitReport(std::make_unique<PathSensitiveBugReport>(
          BT_IndeterminatePosition, BugMessage, N));

d384 2
a385 76
  return State;
}

ProgramStateRef
StreamChecker::ensureFseekWhenceCorrect(SVal WhenceVal, CheckerContext &C,
                                        ProgramStateRef State) const {
  Optional<nonloc::ConcreteInt> CI = WhenceVal.getAs<nonloc::ConcreteInt>();
  if (!CI)
    return State;

  int64_t X = CI->getValue().getSExtValue();
  if (X >= 0 && X <= 2)
    return State;

  if (ExplodedNode *N = C.generateNonFatalErrorNode(State)) {
    C.emitReport(std::make_unique<PathSensitiveBugReport>(
        BT_IllegalWhence,
        "The whence argument to fseek() should be "
        "SEEK_SET, SEEK_END, or SEEK_CUR.",
        N));
    return nullptr;
  }

  return State;
}

void StreamChecker::reportFEofWarning(CheckerContext &C,
                                      ProgramStateRef State) const {
  if (ExplodedNode *N = C.generateNonFatalErrorNode(State)) {
    C.emitReport(std::make_unique<PathSensitiveBugReport>(
        BT_StreamEof,
        "Read function called when stream is in EOF state. "
        "Function has no effect.",
        N));
    return;
  }
  C.addTransition(State);
}

ExplodedNode *
StreamChecker::reportLeaks(const SmallVector<SymbolRef, 2> &LeakedSyms,
                           CheckerContext &C, ExplodedNode *Pred) const {
  ExplodedNode *Err = C.generateNonFatalErrorNode(C.getState(), Pred);
  if (!Err)
    return Pred;

  for (SymbolRef LeakSym : LeakedSyms) {
    // Resource leaks can result in multiple warning that describe the same kind
    // of programming error:
    //  void f() {
    //    FILE *F = fopen("a.txt");
    //    if (rand()) // state split
    //      return; // warning
    //  } // warning
    // While this isn't necessarily true (leaking the same stream could result
    // from a different kinds of errors), the reduction in redundant reports
    // makes this a worthwhile heuristic.
    // FIXME: Add a checker option to turn this uniqueing feature off.
    const ExplodedNode *StreamOpenNode = getAcquisitionSite(Err, LeakSym, C);
    assert(StreamOpenNode && "Could not find place of stream opening.");
    PathDiagnosticLocation LocUsedForUniqueing =
        PathDiagnosticLocation::createBegin(
            StreamOpenNode->getStmtForDiagnostics(), C.getSourceManager(),
            StreamOpenNode->getLocationContext());

    std::unique_ptr<PathSensitiveBugReport> R =
        std::make_unique<PathSensitiveBugReport>(
            BT_ResourceLeak,
            "Opened stream never closed. Potential resource leak.", Err,
            LocUsedForUniqueing,
            StreamOpenNode->getLocationContext()->getDecl());
    R->markInteresting(LeakSym);
    C.emitReport(std::move(R));
  }

  return Err;
d390 1
a390 1
  ProgramStateRef State = C.getState();
d392 3
a394 4
  llvm::SmallVector<SymbolRef, 2> LeakedSyms;

  const StreamMapTy &Map = State->get<StreamMap>();
  for (const auto &I : Map) {
d397 1
a397 1
    if (!SymReaper.isDead(Sym))
a398 4
    if (SS.isOpened())
      LeakedSyms.push_back(Sym);
    State = State->remove<StreamMap>(Sym);
  }
d400 3
a402 3
  ExplodedNode *N = C.getPredecessor();
  if (!LeakedSyms.empty())
    N = reportLeaks(LeakedSyms, C, N);
d404 6
a409 21
  C.addTransition(State, N);
}

ProgramStateRef StreamChecker::checkPointerEscape(
    ProgramStateRef State, const InvalidatedSymbols &Escaped,
    const CallEvent *Call, PointerEscapeKind Kind) const {
  // Check for file-handling system call that is not handled by the checker.
  // FIXME: The checker should be updated to handle all system calls that take
  // 'FILE*' argument. These are now ignored.
  if (Kind == PSK_DirectEscapeOnCall && Call->isInSystemHeader())
    return State;

  for (SymbolRef Sym : Escaped) {
    // The symbol escaped.
    // From now the stream can be manipulated in unknown way to the checker,
    // it is not possible to handle it any more.
    // Optimistically, assume that the corresponding file handle will be closed
    // somewhere else.
    // Remove symbol from state so the following stream calls on this symbol are
    // not handled by the checker.
    State = State->remove<StreamMap>(Sym);
a410 9
  return State;
}

void ento::registerStreamChecker(CheckerManager &Mgr) {
  Mgr.registerChecker<StreamChecker>();
}

bool ento::shouldRegisterStreamChecker(const CheckerManager &Mgr) {
  return true;
d413 2
a414 3
void ento::registerStreamTesterChecker(CheckerManager &Mgr) {
  auto *Checker = Mgr.getChecker<StreamChecker>();
  Checker->TestMode = true;
d417 1
a417 1
bool ento::shouldRegisterStreamTesterChecker(const CheckerManager &Mgr) {
@