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//===--- PthreadLockChecker.cpp - Check for locking problems ---*- C++ -*--===//

// The LLVM Compiler Infrastructure

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

// License. See LICENSE.TXT for details.

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

// This defines PthreadLockChecker, a simple lock -> unlock checker.

// Also handles XNU locks, which behave similarly enough to share code.

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

#include "ClangSACheckers.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/ProgramStateTrait.h"

#include "llvm/ADT/ImmutableList.h"

using namespace clang;

using namespace ento;

namespace {

enum PthreadMutexLockState { Destroyed, Locked, Unlocked };

enum LockingSemantics { NotApplicable = 0, PthreadSemantics, XNUSemantics };

struct LockState {

SmartStateTrait PthreadLockMutexStateTrait;

enum Kind { Destroyed, Locked, Unlocked } K;

SmartStateTrait PthreadLockStackPointerTrait;

private:

struct InitLockSpec {

LockState(Kind K) : K(K) {}

unsigned ArgNo;

};

llvm::StringMap<InitLockSpec> InitLockFunctions = {

{ "pthread_mutex_init" , { 0 } }

};

public:

struct AcquireSpec {

static LockState getLocked() { return LockState(Locked); }

unsigned ArgNo;

static LockState getUnlocked() { return LockState(Unlocked); }

bool IsTrylock;

static LockState getDestroyed() { return LockState(Destroyed); }

LockingSemantics Semantics;

};

llvm::StringMap<AcquireSpec> AcquireLockFunctions = {

{ "pthread_mutex_lock", { 0, false, PthreadSemantics } },

{ "pthread_rwlock_rdlock", { 0, false, PthreadSemantics } },

{ "pthread_rwlock_wrlock", { 0, false, PthreadSemantics } },

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

{ "lck_mtx_lock", { 0, false, XNUSemantics } },

return K == X.K;

{ "lck_rw_lock_exclusive", { 0, false, XNUSemantics } },

}

{ "lck_rw_lock_shared", { 0, false, XNUSemantics } },

bool isLocked() const { return K == Locked; }

{ "pthread_mutex_trylock", { 0, true, PthreadSemantics } },

bool isUnlocked() const { return K == Unlocked; }

{ "pthread_rwlock_tryrdlock", { 0, true, PthreadSemantics } },

bool isDestroyed() const { return K == Destroyed; }

{ "pthread_rwlock_trywrlock", { 0, true, PthreadSemantics } },

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

{ "lck_mtx_try_lock", { 0, true, XNUSemantics } },

ID.AddInteger(K);

{ "lck_rw_try_lock_exclusive", { 0, true, XNUSemantics } },

}

{ "lck_rw_try_lock_shared", { 0, true, XNUSemantics } }

};

Text moved with changes to lines 272-277 (99.2% similarity)

class PthreadLockChecker : public Checker< check::PostStmt<CallExpr> > {

struct ReleaseLockSpec {

mutable std::unique_ptr<BugType> BT_doublelock;

unsigned ArgNo;

mutable std::unique_ptr<BugType> BT_doubleunlock;

};

mutable std::unique_ptr<BugType> BT_destroylock;

llvm::StringMap<ReleaseLockSpec> ReleaseLockFunctions = {

mutable std::unique_ptr<BugType> BT_initlock;

{ "pthread_mutex_unlock", { 0 } },

mutable std::unique_ptr<BugType> BT_lor;

{ "pthread_rwlock_unlock", { 0 } },

enum LockingSemantics {

{ "lck_mtx_unlock", { 0 } },

NotApplicable = 0,

{ "lck_rw_done", { 0 } }

PthreadSemantics,

};

XNUSemantics

struct DestroyLockSpec {

unsigned ArgNo;

};

llvm::StringMap<DestroyLockSpec> DestroyLockFunctions = {

{ "pthread_mutex_destroy", { 0 } },

{ "lck_mtx_destroy", { 0 } },

};

} // end anonymous namespace

namespace {

class PthreadLockMutexStateModel

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

check::PostStmt<CallExpr>> {

public:

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

BugReporter &BR) const;

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

void AcquireLock(CheckerContext &C, const CallExpr *CE, SVal lock,

bool isTryLock, enum LockingSemantics semantics) const;

void ReleaseLock(CheckerContext &C, const CallExpr *CE, SVal lock) const;

void DestroyLock(CheckerContext &C, const CallExpr *CE, SVal Lock) const;

void InitLock(CheckerContext &C, const CallExpr *CE, SVal Lock) const;

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

};

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//===--- PthreadLockChecker.cpp - Check for locking problems ---*- C++ -*--===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This defines PthreadLockChecker, a simple lock -> unlock checker.
// Also handles XNU locks, which behave similarly enough to share code.
//
//===----------------------------------------------------------------------===//

#include "ClangSACheckers.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/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
#include "llvm/ADT/ImmutableList.h"

using namespace clang;
using namespace ento;

namespace {

struct LockState {
  enum Kind { Destroyed, Locked, Unlocked } K;

private:
  LockState(Kind K) : K(K) {}

public:
  static LockState getLocked() { return LockState(Locked); }
  static LockState getUnlocked() { return LockState(Unlocked); }
  static LockState getDestroyed() { return LockState(Destroyed); }

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

bool isLocked() const { return K == Locked; }
  bool isUnlocked() const { return K == Unlocked; }
  bool isDestroyed() const { return K == Destroyed; }

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

class PthreadLockChecker : public Checker< check::PostStmt<CallExpr> > {
  mutable std::unique_ptr<BugType> BT_doublelock;
  mutable std::unique_ptr<BugType> BT_doubleunlock;
  mutable std::unique_ptr<BugType> BT_destroylock;
  mutable std::unique_ptr<BugType> BT_initlock;
  mutable std::unique_ptr<BugType> BT_lor;
  enum LockingSemantics {
    NotApplicable = 0,
    PthreadSemantics,
    XNUSemantics
  };
public:
  void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;

void AcquireLock(CheckerContext &C, const CallExpr *CE, SVal lock,
                   bool isTryLock, enum LockingSemantics semantics) const;

void ReleaseLock(CheckerContext &C, const CallExpr *CE, SVal lock) const;
  void DestroyLock(CheckerContext &C, const CallExpr *CE, SVal Lock) const;
  void InitLock(CheckerContext &C, const CallExpr *CE, SVal Lock) const;
  void reportUseDestroyedBug(CheckerContext &C, const CallExpr *CE) const;
};
} // end anonymous namespace

// GDM Entry for tracking lock state.
REGISTER_LIST_WITH_PROGRAMSTATE(LockSet, const MemRegion *)

REGISTER_MAP_WITH_PROGRAMSTATE(LockMap, const MemRegion *, LockState)

void PthreadLockChecker::checkPostStmt(const CallExpr *CE,
                                       CheckerContext &C) const {
  ProgramStateRef state = C.getState();
  const LocationContext *LCtx = C.getLocationContext();
  StringRef FName = C.getCalleeName(CE);
  if (FName.empty())
    return;

if (CE->getNumArgs() != 1 && CE->getNumArgs() != 2)
    return;

if (FName == "pthread_mutex_lock" ||
      FName == "pthread_rwlock_rdlock" ||
      FName == "pthread_rwlock_wrlock")
    AcquireLock(C, CE, state->getSVal(CE->getArg(0), LCtx),
                false, PthreadSemantics);
  else if (FName == "lck_mtx_lock" ||
           FName == "lck_rw_lock_exclusive" ||
           FName == "lck_rw_lock_shared")
    AcquireLock(C, CE, state->getSVal(CE->getArg(0), LCtx),
                false, XNUSemantics);
  else if (FName == "pthread_mutex_trylock" ||
           FName == "pthread_rwlock_tryrdlock" ||
           FName == "pthread_rwlock_trywrlock")
    AcquireLock(C, CE, state->getSVal(CE->getArg(0), LCtx),
                true, PthreadSemantics);
  else if (FName == "lck_mtx_try_lock" ||
           FName == "lck_rw_try_lock_exclusive" ||
           FName == "lck_rw_try_lock_shared")
    AcquireLock(C, CE, state->getSVal(CE->getArg(0), LCtx),
                true, XNUSemantics);
  else if (FName == "pthread_mutex_unlock" ||
           FName == "pthread_rwlock_unlock" ||
           FName == "lck_mtx_unlock" ||
           FName == "lck_rw_done")
    ReleaseLock(C, CE, state->getSVal(CE->getArg(0), LCtx));
  else if (FName == "pthread_mutex_destroy" ||
           FName == "lck_mtx_destroy")
    DestroyLock(C, CE, state->getSVal(CE->getArg(0), LCtx));
  else if (FName == "pthread_mutex_init")
    InitLock(C, CE, state->getSVal(CE->getArg(0), LCtx));
}

void PthreadLockChecker::AcquireLock(CheckerContext &C, const CallExpr *CE,
                                     SVal lock, bool isTryLock,
                                     enum LockingSemantics semantics) const {

const MemRegion *lockR = lock.getAsRegion();
  if (!lockR)
    return;

ProgramStateRef state = C.getState();

SVal X = state->getSVal(CE, C.getLocationContext());
  if (X.isUnknownOrUndef())
    return;

DefinedSVal retVal = X.castAs<DefinedSVal>();

if (const LockState *LState = state->get<LockMap>(lockR)) {
    if (LState->isLocked()) {
      if (!BT_doublelock)
        BT_doublelock.reset(new BugType(this, "Double locking",
                                        "Lock checker"));
      ExplodedNode *N = C.generateErrorNode();
      if (!N)
        return;
      auto report = llvm::make_unique<BugReport>(
          *BT_doublelock, "This lock has already been acquired", N);
      report->addRange(CE->getArg(0)->getSourceRange());
      C.emitReport(std::move(report));
      return;
    } else if (LState->isDestroyed()) {
      reportUseDestroyedBug(C, CE);
      return;
    }
  }

ProgramStateRef lockSucc = state;
  if (isTryLock) {
    // Bifurcate the state, and allow a mode where the lock acquisition fails.
    ProgramStateRef lockFail;
    switch (semantics) {
    case PthreadSemantics:
      std::tie(lockFail, lockSucc) = state->assume(retVal);
      break;
    case XNUSemantics:
      std::tie(lockSucc, lockFail) = state->assume(retVal);
      break;
    default:
      llvm_unreachable("Unknown tryLock locking semantics");
    }
    assert(lockFail && lockSucc);
    C.addTransition(lockFail);

} else if (semantics == PthreadSemantics) {
    // Assume that the return value was 0.
    lockSucc = state->assume(retVal, false);
    assert(lockSucc);

} else {
    // XNU locking semantics return void on non-try locks
    assert((semantics == XNUSemantics) && "Unknown locking semantics");
    lockSucc = state;
  }

// Record that the lock was acquired.
  lockSucc = lockSucc->add<LockSet>(lockR);
  lockSucc = lockSucc->set<LockMap>(lockR, LockState::getLocked());
  C.addTransition(lockSucc);
}

void PthreadLockChecker::ReleaseLock(CheckerContext &C, const CallExpr *CE,
                                     SVal lock) const {

const MemRegion *lockR = lock.getAsRegion();
  if (!lockR)
    return;

ProgramStateRef state = C.getState();

if (const LockState *LState = state->get<LockMap>(lockR)) {
    if (LState->isUnlocked()) {
      if (!BT_doubleunlock)
        BT_doubleunlock.reset(new BugType(this, "Double unlocking",
                                          "Lock checker"));
      ExplodedNode *N = C.generateErrorNode();
      if (!N)
        return;
      auto Report = llvm::make_unique<BugReport>(
          *BT_doubleunlock, "This lock has already been unlocked", N);
      Report->addRange(CE->getArg(0)->getSourceRange());
      C.emitReport(std::move(Report));
      return;
    } else if (LState->isDestroyed()) {
      reportUseDestroyedBug(C, CE);
      return;
    }
  }

LockSetTy LS = state->get<LockSet>();

// FIXME: Better analysis requires IPA for wrappers.

if (!LS.isEmpty()) {
    const MemRegion *firstLockR = LS.getHead();
    if (firstLockR != lockR) {
      if (!BT_lor)
        BT_lor.reset(new BugType(this, "Lock order reversal", "Lock checker"));
      ExplodedNode *N = C.generateErrorNode();
      if (!N)
        return;
      auto report = llvm::make_unique<BugReport>(
          *BT_lor, "This was not the most recently acquired lock. Possible "
                   "lock order reversal", N);
      report->addRange(CE->getArg(0)->getSourceRange());
      C.emitReport(std::move(report));
      return;
    }
    // Record that the lock was released.
    state = state->set<LockSet>(LS.getTail());
  }

state = state->set<LockMap>(lockR, LockState::getUnlocked());
  C.addTransition(state);
}

void PthreadLockChecker::DestroyLock(CheckerContext &C, const CallExpr *CE,
                                     SVal Lock) const {

const MemRegion *LockR = Lock.getAsRegion();
  if (!LockR)
    return;

ProgramStateRef State = C.getState();

const LockState *LState = State->get<LockMap>(LockR);
  if (!LState || LState->isUnlocked()) {
    State = State->set<LockMap>(LockR, LockState::getDestroyed());
    C.addTransition(State);
    return;
  }

StringRef Message;

if (LState->isLocked()) {
    Message = "This lock is still locked";
  } else {
    Message = "This lock has already been destroyed";
  }

if (!BT_destroylock)
    BT_destroylock.reset(new BugType(this, "Destroy invalid lock",
                                     "Lock checker"));
  ExplodedNode *N = C.generateErrorNode();
  if (!N)
    return;
  auto Report = llvm::make_unique<BugReport>(*BT_destroylock, Message, N);
  Report->addRange(CE->getArg(0)->getSourceRange());
  C.emitReport(std::move(Report));
}

void PthreadLockChecker::InitLock(CheckerContext &C, const CallExpr *CE,
                                  SVal Lock) const {

const MemRegion *LockR = Lock.getAsRegion();
  if (!LockR)
    return;

ProgramStateRef State = C.getState();

const struct LockState *LState = State->get<LockMap>(LockR);
  if (!LState || LState->isDestroyed()) {
    State = State->set<LockMap>(LockR, LockState::getUnlocked());
    C.addTransition(State);
    return;
  }

StringRef Message;

if (LState->isLocked()) {
    Message = "This lock is still being held";
  } else {
    Message = "This lock has already been initialized";
  }

if (!BT_initlock)
    BT_initlock.reset(new BugType(this, "Init invalid lock",
                                  "Lock checker"));
  ExplodedNode *N = C.generateErrorNode();
  if (!N)
    return;
  auto Report = llvm::make_unique<BugReport>(*BT_initlock, Message, N);
  Report->addRange(CE->getArg(0)->getSourceRange());
  C.emitReport(std::move(Report));
}

void PthreadLockChecker::reportUseDestroyedBug(CheckerContext &C,
                                               const CallExpr *CE) const {
  if (!BT_destroylock)
    BT_destroylock.reset(new BugType(this, "Use destroyed lock",
                                     "Lock checker"));
  ExplodedNode *N = C.generateErrorNode();
  if (!N)
    return;
  auto Report = llvm::make_unique<BugReport>(
      *BT_destroylock, "This lock has already been destroyed", N);
  Report->addRange(CE->getArg(0)->getSourceRange());
  C.emitReport(std::move(Report));
}

void ento::registerPthreadLockChecker(CheckerManager &mgr) {
  mgr.registerChecker<PthreadLockChecker>();
}

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#include "ClangSACheckers.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/ProgramStateTrait.h"
#include "llvm/ADT/ImmutableList.h"

using namespace clang;
using namespace ento;

namespace {
enum PthreadMutexLockState { Destroyed, Locked, Unlocked };
enum LockingSemantics { NotApplicable = 0, PthreadSemantics, XNUSemantics };

SmartStateTrait PthreadLockMutexStateTrait;
SmartStateTrait PthreadLockStackPointerTrait;

struct InitLockSpec {
  unsigned ArgNo;
};
llvm::StringMap<InitLockSpec> InitLockFunctions = {
  { "pthread_mutex_init" , { 0 } }
};

struct AcquireSpec {
  unsigned ArgNo;
  bool IsTrylock;
  LockingSemantics Semantics;
};
llvm::StringMap<AcquireSpec> AcquireLockFunctions = {
  { "pthread_mutex_lock",    { 0, false, PthreadSemantics } },
  { "pthread_rwlock_rdlock", { 0, false, PthreadSemantics } },
  { "pthread_rwlock_wrlock", { 0, false, PthreadSemantics } },

{ "lck_mtx_lock",          { 0, false, XNUSemantics } },
  { "lck_rw_lock_exclusive", { 0, false, XNUSemantics } },
  { "lck_rw_lock_shared",    { 0, false, XNUSemantics } },

{ "pthread_mutex_trylock",    { 0, true, PthreadSemantics } },
  { "pthread_rwlock_tryrdlock", { 0, true, PthreadSemantics } },
  { "pthread_rwlock_trywrlock", { 0, true, PthreadSemantics } },

{ "lck_mtx_try_lock",          { 0, true, XNUSemantics } },
  { "lck_rw_try_lock_exclusive", { 0, true, XNUSemantics } },
  { "lck_rw_try_lock_shared",    { 0, true, XNUSemantics } }
};

struct ReleaseLockSpec {
  unsigned ArgNo;
};
llvm::StringMap<ReleaseLockSpec> ReleaseLockFunctions = {
  { "pthread_mutex_unlock",  { 0 } },
  { "pthread_rwlock_unlock", { 0 } },
  { "lck_mtx_unlock",        { 0 } },
  { "lck_rw_done",           { 0 } }
};

struct DestroyLockSpec {
  unsigned ArgNo;
};
llvm::StringMap<DestroyLockSpec> DestroyLockFunctions = {
  { "pthread_mutex_destroy", { 0 } },
  { "lck_mtx_destroy",       { 0 } },
};
} // end anonymous namespace

namespace {
class PthreadLockMutexStateModel
    : public Checker<check::ASTDecl<TranslationUnitDecl>,
                     check::PostStmt<CallExpr>> {
public:
  void checkASTDecl(const TranslationUnitDecl *D, AnalysisManager &AMgr,
                    BugReporter &BR) const;
  void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
};
} // end anonymous namespace

void PthreadLockMutexStateModel::checkASTDecl(const TranslationUnitDecl *D,
                                              AnalysisManager &AMgr,
                                              BugReporter &BR) const {
  PthreadLockMutexStateTrait.initialize("PthreadLockMutexState",
                                        AMgr.getASTContext().IntTy);
}

void PthreadLockMutexStateModel::checkPostStmt(const CallExpr *CE,
                                               CheckerContext &C) const {
  ProgramStateRef state = C.getState();
  StringRef FName = C.getCalleeName(CE);
  if (FName.empty())
    return;

if (CE->getNumArgs() != 1 && CE->getNumArgs() != 2)
    return;

auto InitI = InitLockFunctions.find(FName);
  if (InitI != InitLockFunctions.end()) {
    const auto &Spec = InitI->second;
    const MemRegion *LockR = C.getSVal(CE->getArg(Spec.ArgNo)).getAsRegion();
    if (!LockR)
      return;

SVal OldLState = state->getSVal(PthreadLockMutexStateTrait, LockR);
    if (OldLState.isConstant(Locked) || OldLState.isConstant(Unlocked))
      state = state->bindLoc(PthreadLockMutexStateTrait, LockR, UndefinedVal());
    else
      state = state->bindLoc(PthreadLockMutexStateTrait, LockR, Unlocked);
    C.addTransition(state);
    return;
  }

auto AcquireI = AcquireLockFunctions.find(FName);
  if (AcquireI != AcquireLockFunctions.end()) {
    const auto &Spec = AcquireI->second;
    const MemRegion *LockR = C.getSVal(CE->getArg(Spec.ArgNo)).getAsRegion();
    if (!LockR)
      return;

SVal X = C.getSVal(CE);
    if (X.isUnknownOrUndef())
      return;
    DefinedSVal retVal = X.castAs<DefinedSVal>();

ProgramStateRef lockSucc = state;
    if (Spec.IsTrylock) {
      // Bifurcate the state, and allow a mode where the lock acquisition fails.
      ProgramStateRef lockFail;
      switch (Spec.Semantics) {
      case PthreadSemantics:
        std::tie(lockFail, lockSucc) = state->assume(retVal);
        break;
      case XNUSemantics:
        std::tie(lockSucc, lockFail) = state->assume(retVal);
        break;
      default:
        llvm_unreachable("Unknown tryLock locking semantics");
      }
      assert(lockFail && lockSucc);
      C.addTransition(lockFail);
    } else  if (Spec.Semantics == PthreadSemantics) {
      // Assume that the return value was 0.
      lockSucc = state->assume(retVal, false);
      assert(lockSucc);
    } else {
      // XNU locking semantics return void on non-try locks
      assert((Spec.Semantics == XNUSemantics) && "Unknown locking semantics");
      lockSucc = state;
    }
    lockSucc = lockSucc->bindLoc(PthreadLockMutexStateTrait, LockR, Locked);
    C.addTransition(lockSucc);
    return;
  }

auto ReleaseI = ReleaseLockFunctions.find(FName);
  if (ReleaseI != ReleaseLockFunctions.end()) {
    const auto &Spec = ReleaseI->second;
    const MemRegion *LockR = C.getSVal(CE->getArg(Spec.ArgNo)).getAsRegion();
    if (!LockR)
      return;

SVal OldLState = state->getSVal(PthreadLockMutexStateTrait, LockR);
    if (OldLState.isConstant(Destroyed))
      state = state->bindLoc(PthreadLockMutexStateTrait, LockR, UndefinedVal());
    else
      state = state->bindLoc(PthreadLockMutexStateTrait, LockR, Unlocked);
    C.addTransition(state);
    return;
  }

auto DestroyI = DestroyLockFunctions.find(FName);
  if (DestroyI != DestroyLockFunctions.end()) {
    const auto &Spec = DestroyI->second;
    const MemRegion *LockR = C.getSVal(CE->getArg(Spec.ArgNo)).getAsRegion();
    if (!LockR)
      return;

state = state->bindLoc(PthreadLockMutexStateTrait, LockR, Destroyed);
    C.addTransition(state);
    return;
  }
}

namespace {
class PthreadLockStackModel
    : public Checker<check::ASTDecl<TranslationUnitDecl>,
                     check::PostStmt<CallExpr>> {
public:
  void checkASTDecl(const TranslationUnitDecl *D, AnalysisManager &AMgr,
                    BugReporter &BR) const;
  void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
};
} // end anonymous namespace

void PthreadLockStackModel::checkASTDecl(const TranslationUnitDecl *D,
                                         AnalysisManager &AMgr,
                                         BugReporter &BR) const {
  ASTContext &ACtx = AMgr.getASTContext();
  PthreadLockStackPointerTrait.initialize("PthreadLockStackPointer",
                                          ACtx.getPointerType(ACtx.VoidPtrTy));
}

void PthreadLockStackModel::checkPostStmt(const CallExpr *CE,
                                          CheckerContext &C) const {
  ProgramStateRef state = C.getState();
  StringRef FName = C.getCalleeName(CE);
  if (FName.empty())
    return;

if (CE->getNumArgs() != 1 && CE->getNumArgs() != 2)
    return;

auto AcquireI = AcquireLockFunctions.find(FName);
  if (AcquireI != AcquireLockFunctions.end()) {
    const auto &Spec = AcquireI->second;
    SVal LockR = C.getSVal(CE->getArg(Spec.ArgNo));

// Record that the lock was acquired:
    SValBuilder &SVB = C.getSValBuilder();
    // 1. Increment the current stack pointer location.
    // In order to simplify code, we start at offset 1.
    SVal StackPointer = state->getSVal(PthreadLockStackPointerTrait);
    StackPointer = SVB.evalBinOp(state, BO_Add, StackPointer,
                                 SVB.makeIntValWithPtrWidth(1, true),
                                 PthreadLockStackPointerTrait.getTraitType());
    state = state->bindLoc(PthreadLockStackPointerTrait, StackPointer);
    // 2. Bind the mutex to the current stack pointer location,
    state = state->bindLoc(StackPointer.castAs<Loc>(), LockR);
    C.addTransition(state);
    return;
  }

// Record that the lock was released.
    SValBuilder &SVB = C.getSValBuilder();
    ASTContext &ACtx = SVB.getContext();
    // Essentially, just decrement the current stack pointer location.
    SVal StackPointer = state->getSVal(PthreadLockStackPointerTrait);
    StackPointer = SVB.evalBinOp(state, BO_Sub, StackPointer,
                                 SVB.makeIntValWithPtrWidth(1, true),
                                 ACtx.getPointerType(ACtx.VoidPtrTy));
    state = state->bindLoc(PthreadLockStackPointerTrait, StackPointer);
    C.addTransition(state);
    return;
  }
}

namespace {
class PthreadLockChecker : public Checker<check::PreStmt<CallExpr>> {
  mutable std::unique_ptr<BugType> BT_doublelock;
  mutable std::unique_ptr<BugType> BT_doubleunlock;
  mutable std::unique_ptr<BugType> BT_destroylock;
  mutable std::unique_ptr<BugType> BT_initlock;
  mutable std::unique_ptr<BugType> BT_lor;

void reportBug(std::unique_ptr<BugType> &BT, const Expr *E, CheckerContext &C,
                 StringRef BugName, StringRef Message) const;

public:
  void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
};
} // end anonymous namespace

void PthreadLockChecker::reportBug(std::unique_ptr<BugType> &BT, const Expr *E,
                                   CheckerContext &C, StringRef BugName,
                                   StringRef Message) const {
  if (!BT)
    BT.reset(new BugType(this, BugName, "Lock checker"));
  ExplodedNode *N = C.generateErrorNode();
  if (!N)
    return;
  auto report = llvm::make_unique<BugReport>(*BT, Message, N);
  report->addRange(E->getSourceRange());
  C.emitReport(std::move(report));
}

void PthreadLockChecker::checkPreStmt(const CallExpr *CE,
                                      CheckerContext &C) const {
  ProgramStateRef state = C.getState();
  StringRef FName = C.getCalleeName(CE);
  if (FName.empty())
    return;

if (CE->getNumArgs() != 1 && CE->getNumArgs() != 2)
    return;

auto InitI = InitLockFunctions.find(FName);
  if (InitI != InitLockFunctions.end()) {
    const auto &Spec = InitI->second;
    const Expr *LockE = CE->getArg(Spec.ArgNo);
    const MemRegion *LockR = C.getSVal(LockE).getAsRegion();
    if (!LockR)
      return;

SVal LState = state->getSVal(PthreadLockMutexStateTrait, LockR);
    if (!LState.isConstant() || LState.isConstant(Destroyed))
      return;

StringRef Message;

if (LState.isConstant(Locked)) {
      Message = "This lock is still being held";
    } else {
      Message = "This lock has already been initialized";
    }

reportBug(BT_initlock, LockE, C, "Init invalid lock", Message);
  }

auto AcquireI = AcquireLockFunctions.find(FName);
  if (AcquireI != AcquireLockFunctions.end()) {
    const auto &Spec = AcquireI->second;
    const Expr *LockE = CE->getArg(Spec.ArgNo);
    const MemRegion *LockR = C.getSVal(LockE).getAsRegion();
    if (!LockR)
      return;

SVal LState = state->getSVal(PthreadLockMutexStateTrait, LockR);
    if (LState.isConstant(Locked)) {
      reportBug(BT_doublelock, LockE, C, "Double locking",
                "This lock has already been acquired");
      return;
    }
    if (LState.isConstant(Destroyed)) {
      reportBug(BT_destroylock, LockE, C, "Use destroyed lock",
                "This lock has already been destroyed");
      return;
    }
    return;
  }

auto ReleaseI = ReleaseLockFunctions.find(FName);
  if (ReleaseI != ReleaseLockFunctions.end()) {
    const auto &Spec = ReleaseI->second;
    const Expr *LockE = CE->getArg(Spec.ArgNo);
    const MemRegion *LockR = C.getSVal(LockE).getAsRegion();
    if (!LockR)
      return;

SVal LState = state->getSVal(PthreadLockMutexStateTrait, LockR);
    if (LState.isConstant(Unlocked)) {
      reportBug(BT_doubleunlock, LockE, C, "Double unlocking",
                "This lock has already been unlocked");
      return;
    }

if (LState.isConstant(Destroyed)) {
      reportBug(BT_destroylock, LockE, C, "Use destroyed lock",
                "This lock has already been destroyed");
      return;
    }

const MemRegion *StackPointerR =
        state->getSVal(PthreadLockStackPointerTrait).getAsRegion();
    assert(StackPointerR);

// Below offset 0 on our stack lies the stack frame of the caller function
    // of the top-level function from which we've started our analysis. While
    // we've no problem symbolicating the mutex we last locked in that imaginary
    // caller code, our store model, which thinks of all different base regions
    // as certainly-different, would make us think we're unlocking a different
    // mutex, which is most likely incorrect, so we avoid this check.
    RegionOffset RO = StackPointerR->getAsOffset();
    assert(!RO.hasSymbolicOffset());
    if (RO.getOffset() <= 0) // Recall that we start from 1.
      return;

const MemRegion *firstLockR = state->getSVal(StackPointerR).getAsRegion();
    if (firstLockR && firstLockR != LockR) {
      reportBug(BT_lor, LockE, C, "Lock order reversal",
                "This was not the most recently acquired lock. Possible "
                "lock order reversal");
      return;
    }

return;
  }

auto DestroyI = DestroyLockFunctions.find(FName);
  if (DestroyI != DestroyLockFunctions.end()) {
    const auto &Spec = DestroyI->second;
    const Expr *LockE = CE->getArg(Spec.ArgNo);
    const MemRegion *LockR = C.getSVal(LockE).getAsRegion();
    if (!LockR)
      return;

SVal LState = state->getSVal(PthreadLockMutexStateTrait, LockR);
    if (!LState.isConstant() || LState.isConstant(Unlocked))
      return;

StringRef Message;

if (LState.isConstant(Locked)) {
      Message = "This lock is still locked";
    } else {
      Message = "This lock has already been destroyed";
    }

reportBug(BT_destroylock, LockE, C, "Destroy invalid lock", Message);
    return;
  }
}

void ento::registerPthreadLockCheckerV2(CheckerManager &mgr) {
  mgr.registerChecker<PthreadLockMutexStateModel>();
  mgr.registerChecker<PthreadLockStackModel>();
  mgr.registerChecker<PthreadLockChecker>();
}