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//===-- 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 {

enum SimpleStreamState { Closed, Opened };

SmartStateTrait SimpleStreamTrait;

typedef SmallVector<SymbolRef, 2> SymbolVector;

typedef SmallVector<const MemRegion *, 2> RegionVector;

class SimpleStreamModel

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

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

check::PointerEscape> {

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

bool SimpleStreamModel::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;

}

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.

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

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.

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

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);

}

ProgramStateRef SimpleStreamModel::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 (auto 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.

// FIXME: We're doing double lookup here, and we could have probably just

// deleted the binding, because our checker doesn't discriminate between

// different kind of unknowns.

if (State->hasAnyBinding(SimpleStreamTrait, Sym))

State = State->bindLoc(SimpleStreamTrait, Sym, UnknownVal());

}

return State;

}

namespace {

class SimpleStreamChecker

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

CallDescription CloseFn;

std::unique_ptr<BugType> DoubleCloseBugType;

std::unique_ptr<BugType> LeakBugType;

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//===-- 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 {
enum SimpleStreamState { Closed, Opened };
SmartStateTrait SimpleStreamTrait;
typedef SmallVector<SymbolRef, 2> SymbolVector;

class SimpleStreamModel
    : public Checker<check::ASTDecl<TranslationUnitDecl>, check::PostCall,
                     check::PointerEscape> {
  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

bool SimpleStreamModel::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;
}

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

ProgramStateRef SimpleStreamModel::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 (auto 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.
    // FIXME: We're doing double lookup here, and we could have probably just
    // deleted the binding, because our checker doesn't discriminate between
    // different kind of unknowns.
    if (State->hasAnyBinding(SimpleStreamTrait, Sym))
      State = State->bindLoc(SimpleStreamTrait, Sym, UnknownVal());
  }
  return State;
}

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

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"));

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::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();
  SVal Val = State->getSVal(SimpleStreamTrait, FileDesc);
  if (Val.isConstant(Closed)) {
    reportDoubleClose(FileDesc, Call, C);
    return;
  }
}

static bool isLeaked(SymbolRef Sym, 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.
  ConstraintManager &CMgr = State->getConstraintManager();
  ConditionTruthVal OpenFailed = CMgr.isNull(State, Sym);
  return !OpenFailed.isConstrainedTrue();
}

void SimpleStreamChecker::checkDeadSymbols(SymbolReaper &SymReaper,
                                           CheckerContext &C) const {
  ProgramStateRef State = C.getState();
  SymbolVector 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) {
    SymbolRef FileDesc = *I;
    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(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));
  }
}

void ento::registerSimpleStreamCheckerV2(CheckerManager &mgr) {
  mgr.registerChecker<SimpleStreamModel>();
  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 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;

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;

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>();
}