टेक्स्ट की तुलना करें

दो टेक्स्ट फ़ाइलों के बीच अंतर ढूंढें

रियल-टाइम एडिटर

अपरिवर्तित संक्षिप्त करें

लाइन रैप बंद

लेआउट

परिवर्तन हाइलाइट करें

सिंटैक्स हाइलाइटिंग

Diffchecker Desktop Diffchecker चलाने का सबसे सुरक्षित तरीका। Diffchecker Desktop ऐप पाएं: आपके diffs कभी आपके कंप्यूटर से बाहर नहीं जाते!Desktop पाएं

Untitled diff

बनाया गया 10 वर्ष पहलेDiff कभी समाप्त नहीं होता

156 हटाए गए

लाइनें
कुल
हटाया गया

अक्षर
कुल
हटाया गया

इस सुविधा का उपयोग जारी रखने के लिए, अपग्रेड करें Diffchecker Pro मूल्य देखें

271 लाइनें

105 जोड़े गए

लाइनें
कुल
जोड़ा गया

अक्षर
कुल
जोड़ा गया

इस सुविधा का उपयोग जारी रखने के लिए, अपग्रेड करें Diffchecker Pro मूल्य देखें

223 लाइनें

//===-- SimpleStreamChecker.cpp -----------------------------------------*- C++ -*--//

// The LLVM Compiler Infrastructure

// This file is distributed under the University of Illinois Open Source

// License. See LICENSE.TXT for details.

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

// Defines a checker for proper use of fopen/fclose APIs.

// - If a file has been closed with fclose, it should not be accessed again.

// Accessing a closed file results in undefined behavior.

// - If a file was opened with fopen, it must be closed with fclose before

// the execution ends. Failing to do so results in a resource leak.

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

#include "ClangSACheckers.h"

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

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

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

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

using namespace clang;

using namespace ento;

namespace {

typedef SmallVector<SymbolRef, 2> SymbolVector;

enum SimpleStreamState { Closed, Opened };

SmartStateTrait SimpleStreamTrait;

typedef SmallVector<const MemRegion *, 2> RegionVector;

struct StreamState {

class SimpleStreamModel

private:

: public Checker<check::ASTDecl<TranslationUnitDecl>, check::PostCall> {

enum Kind { Opened, Closed } K;

CallDescription OpenFn, CloseFn;

StreamState(Kind InK) : K(InK) { }

bool guaranteedNotToCloseFile(const CallEvent &Call) const;

public:

bool isOpened() const { return K == Opened; }

SimpleStreamModel() : OpenFn("fopen"), CloseFn("fclose") {}

bool isClosed() const { return K == Closed; }

static StreamState getOpened() { return StreamState(Opened); }

void checkASTDecl(const TranslationUnitDecl *D, AnalysisManager &AMgr,

static StreamState getClosed() { return StreamState(Closed); }

BugReporter &BR) const;

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

ProgramStateRef checkPointerEscape(ProgramStateRef State,

const InvalidatedSymbols &Escaped,

const CallEvent *Call,

PointerEscapeKind Kind) const;

};

} // end of anonymous namespace

bool operator==(const StreamState &X) const {

void SimpleStreamModel::checkASTDecl(const TranslationUnitDecl *D,

return K == X.K;

AnalysisManager &AMgr,

}

BugReporter &BR) const {

void Profile(llvm::FoldingSetNodeID &ID) const {

// Once the AST context is available, we can express the fact that our trait

ID.AddInteger(K);

// has type 'int'.

// FIXME: This is ugly. Maybe make a separate callback, or delay registering

// checkers until AST is constructed?

SimpleStreamTrait.initialize("SimpleStream", AMgr.getASTContext().IntTy);

}

Text moved with changes from lines 117-122 (98.1% similarity)

void SimpleStreamModel::checkPostCall(const CallEvent &Call,

CheckerContext &C) const {

if (!Call.isGlobalCFunction())

return;

if (Call.isCalled(OpenFn)) {

// Get the symbolic value corresponding to the file handle.

const MemRegion *FileDesc = Call.getReturnValue().getAsRegion();

if (!FileDesc)

return;

// Generate the next transition (an edge in the exploded graph).

ProgramStateRef State = C.getState();

State = State->bindLoc(SimpleStreamTrait, FileDesc, Opened);

C.addTransition(State);

} else if (Call.isCalled(CloseFn)) {

// Get the symbolic value corresponding to the file handle.

const MemRegion *FileDesc = Call.getArgSVal(0).getAsRegion();

if (!FileDesc)

return;

// Generate the next transition, in which the stream is closed.

ProgramStateRef State = C.getState();

State = State->bindLoc(SimpleStreamTrait, FileDesc, Closed);

C.addTransition(State);

}

};

}

class SimpleStreamChecker : public Checker<check::PostCall,

namespace {

check::PreCall,

class SimpleStreamChecker

check::DeadSymbols,

: public Checker<check::PreCall, check::DeadSymbols> {

check::PointerEscape> {

CallDescription CloseFn;

CallDescription OpenFn, CloseFn;

std::unique_ptr<BugType> DoubleCloseBugType;

std::unique_ptr<BugType> LeakBugType;

void reportDoubleClose(SymbolRef FileDescSym,

void reportDoubleClose(const MemRegion *FileDescReg,

const CallEvent &Call,

CheckerContext &C) const;

void reportLeaks(ArrayRef<SymbolRef> LeakedStreams, CheckerContext &C,

void reportLeaks(ArrayRef<const MemRegion *> LeakedStreams, CheckerContext &C,

ExplodedNode *ErrNode) const;

bool guaranteedNotToCloseFile(const CallEvent &Call) const;

public:

SimpleStreamChecker();

/// Process fopen.

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

/// Process fclose.

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

/// Detect leaks.

void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;

/// Stop tracking addresses which escape.

ProgramStateRef checkPointerEscape(ProgramStateRef State,

const InvalidatedSymbols &Escaped,

const CallEvent *Call,

PointerEscapeKind Kind) const;

};

} // end anonymous namespace

/// The state of the checker is a map from tracked stream symbols to their

/// state. Let's store it in the ProgramState.

REGISTER_MAP_WITH_PROGRAMSTATE(StreamMap, SymbolRef, StreamState)

namespace {

class StopTrackingCallback final : public SymbolVisitor {

ProgramStateRef state;

public:

StopTrackingCallback(ProgramStateRef st) : state(st) {}

ProgramStateRef getState() const { return state; }

bool VisitSymbol(SymbolRef sym) override {

state = state->remove<StreamMap>(sym);

return true;

}

};

} // end anonymous namespace

SimpleStreamChecker::SimpleStreamChecker()

SimpleStreamChecker::SimpleStreamChecker() : CloseFn("fclose", 1) {

: OpenFn("fopen"), CloseFn("fclose", 1) {

// Initialize the bug types.

DoubleCloseBugType.reset(

new BugType(this, "Double fclose", "Unix Stream API Error"));

LeakBugType.reset(

new BugType(this, "Resource Leak", "Unix Stream API Error"));

// Sinks are higher importance bugs as well as calls to assert() or exit(0).

LeakBugType->setSuppressOnSink(true);

}

Text moved with changes to lines 60-65 (98.1% similarity)

void SimpleStreamChecker::checkPostCall(const CallEvent &Call,

CheckerContext &C) const {

if (!Call.isGlobalCFunction())

return;

if (!Call.isCalled(OpenFn))

return;

// Get the symbolic value corresponding to the file handle.

SymbolRef FileDesc = Call.getReturnValue().getAsSymbol();

if (!FileDesc)

return;

// Generate the next transition (an edge in the exploded graph).

ProgramStateRef State = C.getState();

State = State->set<StreamMap>(FileDesc, StreamState::getOpened());

C.addTransition(State);

}

void SimpleStreamChecker::checkPreCall(const CallEvent &Call,

CheckerContext &C) const {

if (!Call.isGlobalCFunction())

return;

if (!Call.isCalled(CloseFn))

return;

// Get the symbolic value corresponding to the file handle.

SymbolRef FileDesc = Call.getArgSVal(0).getAsSymbol();

const MemRegion *FileDesc = Call.getArgSVal(0).getAsRegion();

if (!FileDesc)

return;

// Check if the stream has already been closed.

ProgramStateRef State = C.getState();

const StreamState *SS = State->get<StreamMap>(FileDesc);

SVal Val = State->getSVal(SimpleStreamTrait, FileDesc);

if (SS && SS->isClosed()) {

if (Val.isConstant(Closed)) {

reportDoubleClose(FileDesc, Call, C);

return;

}

// Generate the next transition, in which the stream is closed.

State = State->set<StreamMap>(FileDesc, StreamState::getClosed());

C.addTransition(State);

}

static bool isLeaked(SymbolRef Sym, const StreamState &SS,

static bool isLeaked(const MemRegion *Reg, ProgramStateRef State) {

bool IsSymDead, ProgramStateRef State) {

// If a symbol is NULL, assume that fopen failed on this path.

if (IsSymDead && SS.isOpened()) {

// A symbol should only be considered leaked if it is non-null.

// If a symbol is NULL, assume that fopen failed on this path.

if (const SymbolicRegion *SR = Reg->getSymbolicBase()) {

// A symbol should only be considered leaked if it is non-null.

SymbolRef Sym = SR->getSymbol();

ConstraintManager &CMgr = State->getConstraintManager();

ConditionTruthVal OpenFailed = CMgr.isNull(State, Sym);

return !OpenFailed.isConstrainedTrue();

}

return false;

}

void SimpleStreamChecker::checkDeadSymbols(SymbolReaper &SymReaper,

CheckerContext &C) const {

ProgramStateRef State = C.getState();

SymbolVector LeakedStreams;

RegionVector LeakedStreams;

StreamMapTy TrackedStreams = State->get<StreamMap>();

// FIXME: Iterate through trait, not through dead symbols (might be faster)?

for (StreamMapTy::iterator I = TrackedStreams.begin(),

for (auto I = SymReaper.dead_begin(), E = SymReaper.dead_end(); I != E; ++I) {

E = TrackedStreams.end(); I != E; ++I) {

// FIXME: This gets uglier with ghost fields.

SymbolRef Sym = I->first;

const MemRegion *FileDesc = C.getSValBuilder().makeLoc(*I).getAsRegion();

bool IsSymDead = SymReaper.isDead(Sym);

SVal Val = State->getSVal(SimpleStreamTrait, FileDesc);

if (!Val.isConstant(Opened))

continue;

// Collect leaked symbols.

if (isLeaked(Sym, I->second, IsSymDead, State))

if (isLeaked(FileDesc, State))

LeakedStreams.push_back(Sym);

LeakedStreams.push_back(FileDesc);

// Remove the dead symbol from the streams map.

if (IsSymDead)

State = State->remove<StreamMap>(Sym);

}

if (LeakedStreams.empty())

return;

ExplodedNode *N = C.generateNonFatalErrorNode(State);

if (!N)

return;

reportLeaks(LeakedStreams, C, N);

}

void SimpleStreamChecker::reportDoubleClose(SymbolRef FileDescSym,

void SimpleStreamChecker::reportDoubleClose(const MemRegion *FileDescReg,

const CallEvent &Call,

CheckerContext &C) const {

// We reached a bug, stop exploring the path here by generating a sink.

ExplodedNode *ErrNode = C.generateErrorNode();

// If we've already reached this node on another path, return.

if (!ErrNode)

return;

// Generate the report.

auto R = llvm::make_unique<BugReport>(*DoubleCloseBugType,

"Closing a previously closed file stream", ErrNode);

R->addRange(Call.getSourceRange());

R->markInteresting(FileDescSym);

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

}

void SimpleStreamChecker::reportLeaks(ArrayRef<SymbolRef> LeakedStreams,

void SimpleStreamChecker::reportLeaks(ArrayRef<const MemRegion *> LeakedStreams,

CheckerContext &C,

ExplodedNode *ErrNode) const {

// Attach bug reports to the leak node.

// TODO: Identify the leaked file descriptor.

for (SymbolRef LeakedStream : LeakedStreams) {

for (const MemRegion *LeakedStream : LeakedStreams) {

auto R = llvm::make_unique<BugReport>(*LeakBugType,

"Opened file is never closed; potential resource leak", ErrNode);

R->markInteresting(LeakedStream);

if (const SymbolicRegion *SR = LeakedStream->getSymbolicBase())

R->markInteresting(SR->getSymbol());

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

}

bool SimpleStreamChecker::guaranteedNotToCloseFile(const CallEvent &Call) const{

void ento::registerSimpleStreamCheckerV3(CheckerManager &mgr) {

// If it's not in a system header, assume it might close a file.

mgr.registerChecker<SimpleStreamModel>();

if (!Call.isInSystemHeader())

return false;

// Handle cases where we know a buffer's /address/ can escape.

if (Call.argumentsMayEscape())

return false;

// Note, even though fclose closes the file, we do not list it here

// since the checker is modeling the call.

return true;

}

// If the pointer we are tracking escaped, do not track the symbol as

// we cannot reason about it anymore.

ProgramStateRef

SimpleStreamChecker::checkPointerEscape(ProgramStateRef State,

const InvalidatedSymbols &Escaped,

const CallEvent *Call,

PointerEscapeKind Kind) const {

// If we know that the call cannot close a file, there is nothing to do.

if (Kind == PSK_DirectEscapeOnCall && guaranteedNotToCloseFile(*Call)) {

return State;

}

for (InvalidatedSymbols::const_iterator I = Escaped.begin(),

E = Escaped.end();

I != E; ++I) {

SymbolRef Sym = *I;

// The symbol escaped. Optimistically, assume that the corresponding file

// handle will be closed somewhere else.

State = State->remove<StreamMap>(Sym);

}

return State;

}

void ento::registerSimpleStreamChecker(CheckerManager &mgr) {

mgr.registerChecker<SimpleStreamChecker>();

}

सेव किए गए Diffs

ऑरिजनल टेक्स्ट

फ़ाइल खोलें

//===-- SimpleStreamChecker.cpp -----------------------------------------*- C++ -*--//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Defines a checker for proper use of fopen/fclose APIs.
//   - If a file has been closed with fclose, it should not be accessed again.
//   Accessing a closed file results in undefined behavior.
//   - If a file was opened with fopen, it must be closed with fclose before
//   the execution ends. Failing to do so results in a resource leak.
//
//===----------------------------------------------------------------------===//

#include "ClangSACheckers.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"

using namespace clang;
using namespace ento;

namespace {
typedef SmallVector<SymbolRef, 2> SymbolVector;

struct StreamState {
private:
  enum Kind { Opened, Closed } K;
  StreamState(Kind InK) : K(InK) { }

public:
  bool isOpened() const { return K == Opened; }
  bool isClosed() const { return K == Closed; }

static StreamState getOpened() { return StreamState(Opened); }
  static StreamState getClosed() { return StreamState(Closed); }

bool operator==(const StreamState &X) const {
    return K == X.K;
  }
  void Profile(llvm::FoldingSetNodeID &ID) const {
    ID.AddInteger(K);
  }
};

class SimpleStreamChecker : public Checker<check::PostCall,
                                           check::PreCall,
                                           check::DeadSymbols,
                                           check::PointerEscape> {
  CallDescription OpenFn, CloseFn;

std::unique_ptr<BugType> DoubleCloseBugType;
  std::unique_ptr<BugType> LeakBugType;

void reportDoubleClose(SymbolRef FileDescSym,
                         const CallEvent &Call,
                         CheckerContext &C) const;

void reportLeaks(ArrayRef<SymbolRef> LeakedStreams, CheckerContext &C,
                   ExplodedNode *ErrNode) const;

bool guaranteedNotToCloseFile(const CallEvent &Call) const;

public:
  SimpleStreamChecker();

/// Process fopen.
  void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
  /// Process fclose.
  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;

void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;

/// Stop tracking addresses which escape.
  ProgramStateRef checkPointerEscape(ProgramStateRef State,
                                    const InvalidatedSymbols &Escaped,
                                    const CallEvent *Call,
                                    PointerEscapeKind Kind) const;
};

} // end anonymous namespace

/// The state of the checker is a map from tracked stream symbols to their
/// state. Let's store it in the ProgramState.
REGISTER_MAP_WITH_PROGRAMSTATE(StreamMap, SymbolRef, StreamState)

namespace {
class StopTrackingCallback final : public SymbolVisitor {
  ProgramStateRef state;
public:
  StopTrackingCallback(ProgramStateRef st) : state(st) {}
  ProgramStateRef getState() const { return state; }

bool VisitSymbol(SymbolRef sym) override {
    state = state->remove<StreamMap>(sym);
    return true;
  }
};
} // end anonymous namespace

SimpleStreamChecker::SimpleStreamChecker()
    : OpenFn("fopen"), CloseFn("fclose", 1) {
  // Initialize the bug types.
  DoubleCloseBugType.reset(
      new BugType(this, "Double fclose", "Unix Stream API Error"));

LeakBugType.reset(
      new BugType(this, "Resource Leak", "Unix Stream API Error"));
  // Sinks are higher importance bugs as well as calls to assert() or exit(0).
  LeakBugType->setSuppressOnSink(true);
}

void SimpleStreamChecker::checkPostCall(const CallEvent &Call,
                                        CheckerContext &C) const {
  if (!Call.isGlobalCFunction())
    return;

if (!Call.isCalled(OpenFn))
    return;

// Get the symbolic value corresponding to the file handle.
  SymbolRef FileDesc = Call.getReturnValue().getAsSymbol();
  if (!FileDesc)
    return;

// Generate the next transition (an edge in the exploded graph).
  ProgramStateRef State = C.getState();
  State = State->set<StreamMap>(FileDesc, StreamState::getOpened());
  C.addTransition(State);
}

void SimpleStreamChecker::checkPreCall(const CallEvent &Call,
                                       CheckerContext &C) const {
  if (!Call.isGlobalCFunction())
    return;

if (!Call.isCalled(CloseFn))
    return;

// Get the symbolic value corresponding to the file handle.
  SymbolRef FileDesc = Call.getArgSVal(0).getAsSymbol();
  if (!FileDesc)
    return;

// Check if the stream has already been closed.
  ProgramStateRef State = C.getState();
  const StreamState *SS = State->get<StreamMap>(FileDesc);
  if (SS && SS->isClosed()) {
    reportDoubleClose(FileDesc, Call, C);
    return;
  }

// Generate the next transition, in which the stream is closed.
  State = State->set<StreamMap>(FileDesc, StreamState::getClosed());
  C.addTransition(State);
}

static bool isLeaked(SymbolRef Sym, const StreamState &SS,
                     bool IsSymDead, ProgramStateRef State) {
  if (IsSymDead && SS.isOpened()) {
    // If a symbol is NULL, assume that fopen failed on this path.
    // A symbol should only be considered leaked if it is non-null.
    ConstraintManager &CMgr = State->getConstraintManager();
    ConditionTruthVal OpenFailed = CMgr.isNull(State, Sym);
    return !OpenFailed.isConstrainedTrue();
  }
  return false;
}

void SimpleStreamChecker::checkDeadSymbols(SymbolReaper &SymReaper,
                                           CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SymbolVector LeakedStreams;
  StreamMapTy TrackedStreams = State->get<StreamMap>();
  for (StreamMapTy::iterator I = TrackedStreams.begin(),
                             E = TrackedStreams.end(); I != E; ++I) {
    SymbolRef Sym = I->first;
    bool IsSymDead = SymReaper.isDead(Sym);

// Collect leaked symbols.
    if (isLeaked(Sym, I->second, IsSymDead, State))
      LeakedStreams.push_back(Sym);

// Remove the dead symbol from the streams map.
    if (IsSymDead)
      State = State->remove<StreamMap>(Sym);
  }

ExplodedNode *N = C.generateNonFatalErrorNode(State);
  if (!N)
    return;
  reportLeaks(LeakedStreams, C, N);
}

void SimpleStreamChecker::reportDoubleClose(SymbolRef FileDescSym,
                                            const CallEvent &Call,
                                            CheckerContext &C) const {
  // We reached a bug, stop exploring the path here by generating a sink.
  ExplodedNode *ErrNode = C.generateErrorNode();
  // If we've already reached this node on another path, return.
  if (!ErrNode)
    return;

// Generate the report.
  auto R = llvm::make_unique<BugReport>(*DoubleCloseBugType,
      "Closing a previously closed file stream", ErrNode);
  R->addRange(Call.getSourceRange());
  R->markInteresting(FileDescSym);
  C.emitReport(std::move(R));
}

void SimpleStreamChecker::reportLeaks(ArrayRef<SymbolRef> LeakedStreams,
                                      CheckerContext &C,
                                      ExplodedNode *ErrNode) const {
  // Attach bug reports to the leak node.
  // TODO: Identify the leaked file descriptor.
  for (SymbolRef LeakedStream : LeakedStreams) {
    auto R = llvm::make_unique<BugReport>(*LeakBugType,
        "Opened file is never closed; potential resource leak", ErrNode);
    R->markInteresting(LeakedStream);
    C.emitReport(std::move(R));
  }
}

bool SimpleStreamChecker::guaranteedNotToCloseFile(const CallEvent &Call) const{
  // If it's not in a system header, assume it might close a file.
  if (!Call.isInSystemHeader())
    return false;

// Handle cases where we know a buffer's /address/ can escape.
  if (Call.argumentsMayEscape())
    return false;

// Note, even though fclose closes the file, we do not list it here
  // since the checker is modeling the call.

return true;
}

// If the pointer we are tracking escaped, do not track the symbol as
// we cannot reason about it anymore.
ProgramStateRef
SimpleStreamChecker::checkPointerEscape(ProgramStateRef State,
                                        const InvalidatedSymbols &Escaped,
                                        const CallEvent *Call,
                                        PointerEscapeKind Kind) const {
  // If we know that the call cannot close a file, there is nothing to do.
  if (Kind == PSK_DirectEscapeOnCall && guaranteedNotToCloseFile(*Call)) {
    return State;
  }

for (InvalidatedSymbols::const_iterator I = Escaped.begin(),
                                          E = Escaped.end();
                                          I != E; ++I) {
    SymbolRef Sym = *I;

// The symbol escaped. Optimistically, assume that the corresponding file
    // handle will be closed somewhere else.
    State = State->remove<StreamMap>(Sym);
  }
  return State;
}

void ento::registerSimpleStreamChecker(CheckerManager &mgr) {
  mgr.registerChecker<SimpleStreamChecker>();
}

परिवर्तित टेक्स्ट

फ़ाइल खोलें

using namespace clang;
using namespace ento;

namespace {
enum SimpleStreamState { Closed, Opened };
SmartStateTrait SimpleStreamTrait;
typedef SmallVector<const MemRegion *, 2> RegionVector;

class SimpleStreamModel
    : public Checker<check::ASTDecl<TranslationUnitDecl>, check::PostCall> {
  CallDescription OpenFn, CloseFn;
  bool guaranteedNotToCloseFile(const CallEvent &Call) const;

public:
  SimpleStreamModel() : OpenFn("fopen"), CloseFn("fclose") {}

void checkASTDecl(const TranslationUnitDecl *D, AnalysisManager &AMgr,
                    BugReporter &BR) const;
  void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
  ProgramStateRef checkPointerEscape(ProgramStateRef State,
                                     const InvalidatedSymbols &Escaped,
                                     const CallEvent *Call,
                                     PointerEscapeKind Kind) const;
};
} // end of anonymous namespace

void SimpleStreamModel::checkASTDecl(const TranslationUnitDecl *D,
                                       AnalysisManager &AMgr,
                                       BugReporter &BR) const {
  // Once the AST context is available, we can express the fact that our trait
  // has type 'int'.
  // FIXME: This is ugly. Maybe make a separate callback, or delay registering
  // checkers until AST is constructed?
  SimpleStreamTrait.initialize("SimpleStream", AMgr.getASTContext().IntTy);
}

void SimpleStreamModel::checkPostCall(const CallEvent &Call,
                                        CheckerContext &C) const {
  if (!Call.isGlobalCFunction())
    return;

if (Call.isCalled(OpenFn)) {

// Get the symbolic value corresponding to the file handle.
    const MemRegion *FileDesc = Call.getReturnValue().getAsRegion();
    if (!FileDesc)
      return;

// Generate the next transition (an edge in the exploded graph).
    ProgramStateRef State = C.getState();
    State = State->bindLoc(SimpleStreamTrait, FileDesc, Opened);
    C.addTransition(State);

} else if (Call.isCalled(CloseFn)) {

// Get the symbolic value corresponding to the file handle.
    const MemRegion *FileDesc = Call.getArgSVal(0).getAsRegion();
    if (!FileDesc)
      return;

// Generate the next transition, in which the stream is closed.
    ProgramStateRef State = C.getState();
    State = State->bindLoc(SimpleStreamTrait, FileDesc, Closed);
    C.addTransition(State);
  }
}

namespace {
class SimpleStreamChecker
    : public Checker<check::PreCall, check::DeadSymbols> {
  CallDescription CloseFn;

std::unique_ptr<BugType> DoubleCloseBugType;
  std::unique_ptr<BugType> LeakBugType;

void reportDoubleClose(const MemRegion *FileDescReg,
                         const CallEvent &Call,
                         CheckerContext &C) const;

void reportLeaks(ArrayRef<const MemRegion *> LeakedStreams, CheckerContext &C,
                   ExplodedNode *ErrNode) const;

public:
  SimpleStreamChecker();

/// Process fclose.
  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;

/// Detect leaks.
  void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
};
} // end anonymous namespace

SimpleStreamChecker::SimpleStreamChecker() : CloseFn("fclose", 1) {
  // Initialize the bug types.
  DoubleCloseBugType.reset(
      new BugType(this, "Double fclose", "Unix Stream API Error"));

void SimpleStreamChecker::checkPreCall(const CallEvent &Call,
                                       CheckerContext &C) const {
  if (!Call.isGlobalCFunction())
    return;

if (!Call.isCalled(CloseFn))
    return;

// Get the symbolic value corresponding to the file handle.
  const MemRegion *FileDesc = Call.getArgSVal(0).getAsRegion();
  if (!FileDesc)
    return;

// Check if the stream has already been closed.
  ProgramStateRef State = C.getState();
  SVal Val = State->getSVal(SimpleStreamTrait, FileDesc);
  if (Val.isConstant(Closed)) {
    reportDoubleClose(FileDesc, Call, C);
    return;
  }
}

static bool isLeaked(const MemRegion *Reg, ProgramStateRef State) {
  // If a symbol is NULL, assume that fopen failed on this path.
  // A symbol should only be considered leaked if it is non-null.
  if (const SymbolicRegion *SR = Reg->getSymbolicBase()) {
    SymbolRef Sym = SR->getSymbol();
    ConstraintManager &CMgr = State->getConstraintManager();
    ConditionTruthVal OpenFailed = CMgr.isNull(State, Sym);
    return !OpenFailed.isConstrainedTrue();
  }
  return false;
}

void SimpleStreamChecker::checkDeadSymbols(SymbolReaper &SymReaper,
                                           CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  RegionVector LeakedStreams;
  // FIXME: Iterate through trait, not through dead symbols (might be faster)?
  for (auto I = SymReaper.dead_begin(), E = SymReaper.dead_end(); I != E; ++I) {
    // FIXME: This gets uglier with ghost fields.
    const MemRegion *FileDesc = C.getSValBuilder().makeLoc(*I).getAsRegion();
    SVal Val = State->getSVal(SimpleStreamTrait, FileDesc);
    if (!Val.isConstant(Opened))
      continue;

// Collect leaked symbols.
    if (isLeaked(FileDesc, State))
      LeakedStreams.push_back(FileDesc);
  }

if (LeakedStreams.empty())
    return;

ExplodedNode *N = C.generateNonFatalErrorNode(State);
  if (!N)
    return;
  reportLeaks(LeakedStreams, C, N);
}

void SimpleStreamChecker::reportDoubleClose(const MemRegion *FileDescReg,
                                            const CallEvent &Call,
                                            CheckerContext &C) const {
  // We reached a bug, stop exploring the path here by generating a sink.
  ExplodedNode *ErrNode = C.generateErrorNode();
  // If we've already reached this node on another path, return.
  if (!ErrNode)
    return;

void SimpleStreamChecker::reportLeaks(ArrayRef<const MemRegion *> LeakedStreams,
                                      CheckerContext &C,
                                      ExplodedNode *ErrNode) const {
  // Attach bug reports to the leak node.
  // TODO: Identify the leaked file descriptor.
  for (const MemRegion *LeakedStream : LeakedStreams) {
    auto R = llvm::make_unique<BugReport>(*LeakBugType,
        "Opened file is never closed; potential resource leak", ErrNode);
    if (const SymbolicRegion *SR = LeakedStream->getSymbolicBase())
      R->markInteresting(SR->getSymbol());
    C.emitReport(std::move(R));
  }
}

void ento::registerSimpleStreamCheckerV3(CheckerManager &mgr) {
  mgr.registerChecker<SimpleStreamModel>();
  mgr.registerChecker<SimpleStreamChecker>();
}