//=== MallocChecker.cpp - A malloc/free checker -------------------*- 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 a variety of memory management related checkers, such as
// leak, double free, and use-after-free.
//
// The following checkers are defined here:
//
//   * MallocChecker
//       Despite its name, it models all sorts of memory allocations and
//       de- or reallocation, including but not limited to malloc, free,
//       relloc, new, delete. It also reports on a variety of memory misuse
//       errors.
//       Many other checkers interact very closely with this checker, in fact,
//       most are merely options to this one. Other checkers may register
//       MallocChecker, but do not enable MallocChecker's reports (more details
//       to follow around its field, ChecksEnabled).
//       It also has a boolean "Optimistic" checker option, which if set to true
//       will cause the checker to model user defined memory management related
//       functions annotated via the attribute ownership_takes, ownership_holds
//       and ownership_returns.
//
//   * NewDeleteChecker
//       Enables the modeling of new, new[], delete, delete[] in MallocChecker,
//       and checks for related double-free and use-after-free errors.
//
//   * NewDeleteLeaksChecker
//       Checks for leaks related to new, new[], delete, delete[].
//       Depends on NewDeleteChecker.
//
//   * MismatchedDeallocatorChecker
//       Enables checking whether memory is deallocated with the corresponding
//       allocation function in MallocChecker, such as malloc() allocated
//       regions are only freed by free(), new by delete, new[] by delete[].
//
//  InnerPointerChecker interacts very closely with MallocChecker, but unlike
//  the above checkers, it has it's own file, hence the many InnerPointerChecker
//  related headers and non-static functions.
//
//===----------------------------------------------------------------------===//

#include "AllocationState.h"
#include "InterCheckerAPI.h"
#include "NoOwnershipChangeVisitor.h"
#include "clang/AST/Attr.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ParentMap.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/Analysis/ProgramPoint.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Lex/Lexer.h"
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Checkers/Taint.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/BugReporter/CommonBugCategories.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerHelpers.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/DynamicExtent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState_Fwd.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <functional>
#include <optional>
#include <utility>

using namespace clang;
using namespace ento;
using namespace std::placeholders;

//===----------------------------------------------------------------------===//
// The types of allocation we're modeling. This is used to check whether a
// dynamically allocated object is deallocated with the correct function, like
// not using operator delete on an object created by malloc(), or alloca regions
// aren't ever deallocated manually.
//===----------------------------------------------------------------------===//

namespace {

// Used to check correspondence between allocators and deallocators.
enum AllocationFamilyKind {
  AF_None,
  AF_Malloc,
  AF_CXXNew,
  AF_CXXNewArray,
  AF_IfNameIndex,
  AF_Alloca,
  AF_InnerBuffer,
  AF_Custom,
};

struct AllocationFamily {
  AllocationFamilyKind Kind;
  std::optional<StringRef> CustomName;

  explicit AllocationFamily(AllocationFamilyKind AKind,
                            std::optional<StringRef> Name = std::nullopt)
      : Kind(AKind), CustomName(Name) {
    assert((Kind != AF_Custom || CustomName.has_value()) &&
           "Custom family must specify also the name");

    // Preseve previous behavior when "malloc" class means AF_Malloc
    if (Kind == AF_Custom && CustomName.value() == "malloc") {
      Kind = AF_Malloc;
      CustomName = std::nullopt;
    }
  }

  bool operator==(const AllocationFamily &Other) const {
    return std::tie(Kind, CustomName) == std::tie(Other.Kind, Other.CustomName);
  }

  bool operator!=(const AllocationFamily &Other) const {
    return !(*this == Other);
  }

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

    if (Kind == AF_Custom)
      ID.AddString(CustomName.value());
  }
};

} // end of anonymous namespace

/// Print names of allocators and deallocators.
///
/// \returns true on success.
static bool printMemFnName(raw_ostream &os, CheckerContext &C, const Expr *E);

/// Print expected name of an allocator based on the deallocator's family
/// derived from the DeallocExpr.
static void printExpectedAllocName(raw_ostream &os, AllocationFamily Family);

/// Print expected name of a deallocator based on the allocator's
/// family.
static void printExpectedDeallocName(raw_ostream &os, AllocationFamily Family);

//===----------------------------------------------------------------------===//
// The state of a symbol, in terms of memory management.
//===----------------------------------------------------------------------===//

namespace {

class RefState {
  enum Kind {
    // Reference to allocated memory.
    Allocated,
    // Reference to zero-allocated memory.
    AllocatedOfSizeZero,
    // Reference to released/freed memory.
    Released,
    // The responsibility for freeing resources has transferred from
    // this reference. A relinquished symbol should not be freed.
    Relinquished,
    // We are no longer guaranteed to have observed all manipulations
    // of this pointer/memory. For example, it could have been
    // passed as a parameter to an opaque function.
    Escaped
  };

  const Stmt *S;

  Kind K;
  AllocationFamily Family;

  RefState(Kind k, const Stmt *s, AllocationFamily family)
      : S(s), K(k), Family(family) {
    assert(family.Kind != AF_None);
  }

public:
  bool isAllocated() const { return K == Allocated; }
  bool isAllocatedOfSizeZero() const { return K == AllocatedOfSizeZero; }
  bool isReleased() const { return K == Released; }
  bool isRelinquished() const { return K == Relinquished; }
  bool isEscaped() const { return K == Escaped; }
  AllocationFamily getAllocationFamily() const { return Family; }
  const Stmt *getStmt() const { return S; }

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

  static RefState getAllocated(AllocationFamily family, const Stmt *s) {
    return RefState(Allocated, s, family);
  }
  static RefState getAllocatedOfSizeZero(const RefState *RS) {
    return RefState(AllocatedOfSizeZero, RS->getStmt(),
                    RS->getAllocationFamily());
  }
  static RefState getReleased(AllocationFamily family, const Stmt *s) {
    return RefState(Released, s, family);
  }
  static RefState getRelinquished(AllocationFamily family, const Stmt *s) {
    return RefState(Relinquished, s, family);
  }
  static RefState getEscaped(const RefState *RS) {
    return RefState(Escaped, RS->getStmt(), RS->getAllocationFamily());
  }

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

  LLVM_DUMP_METHOD void dump(raw_ostream &OS) const {
    switch (K) {
#define CASE(ID) case ID: OS << #ID; break;
    CASE(Allocated)
    CASE(AllocatedOfSizeZero)
    CASE(Released)
    CASE(Relinquished)
    CASE(Escaped)
    }
  }

  LLVM_DUMP_METHOD void dump() const { dump(llvm::errs()); }
};

} // end of anonymous namespace

REGISTER_MAP_WITH_PROGRAMSTATE(RegionState, SymbolRef, RefState)

/// Check if the memory associated with this symbol was released.
static bool isReleased(SymbolRef Sym, CheckerContext &C);

/// Update the RefState to reflect the new memory allocation.
/// The optional \p RetVal parameter specifies the newly allocated pointer
/// value; if unspecified, the value of expression \p E is used.
static ProgramStateRef
MallocUpdateRefState(CheckerContext &C, const Expr *E, ProgramStateRef State,
                     AllocationFamily Family,
                     std::optional<SVal> RetVal = std::nullopt);

//===----------------------------------------------------------------------===//
// The modeling of memory reallocation.
//
// The terminology 'toPtr' and 'fromPtr' will be used:
//   toPtr = realloc(fromPtr, 20);
//===----------------------------------------------------------------------===//

REGISTER_SET_WITH_PROGRAMSTATE(ReallocSizeZeroSymbols, SymbolRef)

namespace {

/// The state of 'fromPtr' after reallocation is known to have failed.
enum OwnershipAfterReallocKind {
  // The symbol needs to be freed (e.g.: realloc)
  OAR_ToBeFreedAfterFailure,
  // The symbol has been freed (e.g.: reallocf)
  OAR_FreeOnFailure,
  // The symbol doesn't have to freed (e.g.: we aren't sure if, how and where
  // 'fromPtr' was allocated:
  //    void Haha(int *ptr) {
  //      ptr = realloc(ptr, 67);
  //      // ...
  //    }
  // ).
  OAR_DoNotTrackAfterFailure
};

/// Stores information about the 'fromPtr' symbol after reallocation.
///
/// This is important because realloc may fail, and that needs special modeling.
/// Whether reallocation failed or not will not be known until later, so we'll
/// store whether upon failure 'fromPtr' will be freed, or needs to be freed
/// later, etc.
struct ReallocPair {

  // The 'fromPtr'.
  SymbolRef ReallocatedSym;
  OwnershipAfterReallocKind Kind;

  ReallocPair(SymbolRef S, OwnershipAfterReallocKind K)
      : ReallocatedSym(S), Kind(K) {}
  void Profile(llvm::FoldingSetNodeID &ID) const {
    ID.AddInteger(Kind);
    ID.AddPointer(ReallocatedSym);
  }
  bool operator==(const ReallocPair &X) const {
    return ReallocatedSym == X.ReallocatedSym &&
           Kind == X.Kind;
  }
};

} // end of anonymous namespace

REGISTER_MAP_WITH_PROGRAMSTATE(ReallocPairs, SymbolRef, ReallocPair)

static bool isStandardNew(const FunctionDecl *FD);
static bool isStandardNew(const CallEvent &Call) {
  if (!Call.getDecl() || !isa<FunctionDecl>(Call.getDecl()))
    return false;
  return isStandardNew(cast<FunctionDecl>(Call.getDecl()));
}

static bool isStandardDelete(const FunctionDecl *FD);
static bool isStandardDelete(const CallEvent &Call) {
  if (!Call.getDecl() || !isa<FunctionDecl>(Call.getDecl()))
    return false;
  return isStandardDelete(cast<FunctionDecl>(Call.getDecl()));
}

/// Tells if the callee is one of the builtin new/delete operators, including
/// placement operators and other standard overloads.
template <typename T> static bool isStandardNewDelete(const T &FD) {
  return isStandardDelete(FD) || isStandardNew(FD);
}

namespace {

//===----------------------------------------------------------------------===//
// Utility classes that provide access to the bug types and can model that some
// of the bug types are shared by multiple checker frontends.
//===----------------------------------------------------------------------===//

#define BUGTYPE_PROVIDER(NAME, DEF)                                            \
  struct NAME : virtual public CheckerFrontend {                               \
    BugType NAME##Bug{this, DEF, categories::MemoryError};                     \
  };

BUGTYPE_PROVIDER(DoubleFree, "Double free")

struct Leak : virtual public CheckerFrontend {
  // Leaks should not be reported if they are post-dominated by a sink:
  // (1) Sinks are higher importance bugs.
  // (2) NoReturnFunctionChecker uses sink nodes to represent paths ending
  //     with __noreturn functions such as assert() or exit(). We choose not
  //     to report leaks on such paths.
  BugType LeakBug{this, "Memory leak", categories::MemoryError,
                  /*SuppressOnSink=*/true};
};

BUGTYPE_PROVIDER(UseFree, "Use-after-free")
BUGTYPE_PROVIDER(BadFree, "Bad free")
BUGTYPE_PROVIDER(FreeAlloca, "Free 'alloca()'")
BUGTYPE_PROVIDER(MismatchedDealloc, "Bad deallocator")
BUGTYPE_PROVIDER(OffsetFree, "Offset free")
BUGTYPE_PROVIDER(UseZeroAllocated, "Use of zero allocated")

#undef BUGTYPE_PROVIDER

template <typename... BT_PROVIDERS>
struct DynMemFrontend : virtual public CheckerFrontend, public BT_PROVIDERS... {
  template <typename T> const T *getAs() const {
    if constexpr (std::is_same_v<T, CheckerFrontend> ||
                  (std::is_same_v<T, BT_PROVIDERS> || ...))
      return static_cast<const T *>(this);
    return nullptr;
  }
};

//===----------------------------------------------------------------------===//
// Definition of the MallocChecker class.
//===----------------------------------------------------------------------===//

class MallocChecker
    : public CheckerFamily<
          check::DeadSymbols, check::PointerEscape, check::ConstPointerEscape,
          check::PreStmt<ReturnStmt>, check::EndFunction, check::PreCall,
          check::PostCall, eval::Call, check::NewAllocator,
          check::PostStmt<BlockExpr>, check::PostObjCMessage, check::Location,
          eval::Assume> {
public:
  /// In pessimistic mode, the checker assumes that it does not know which
  /// functions might free the memory.
  /// In optimistic mode, the checker assumes that all user-defined functions
  /// which might free a pointer are annotated.
  bool ShouldIncludeOwnershipAnnotatedFunctions = false;

  bool ShouldRegisterNoOwnershipChangeVisitor = false;

  // This checker family implements many bug types and frontends, and several
  // bug types are shared between multiple frontends, so most of the frontends
  // are declared with the helper class DynMemFrontend.
  // FIXME: There is no clear reason for separating NewDelete vs NewDeleteLeaks
  // while e.g. MallocChecker covers both non-leak and leak bugs together. It
  // would be nice to redraw the boundaries between the frontends in a more
  // logical way.
  DynMemFrontend<DoubleFree, Leak, UseFree, BadFree, FreeAlloca, OffsetFree,
                 UseZeroAllocated>
      MallocChecker;
  DynMemFrontend<DoubleFree, UseFree, BadFree, OffsetFree, UseZeroAllocated>
      NewDeleteChecker;
  DynMemFrontend<Leak> NewDeleteLeaksChecker;
  DynMemFrontend<FreeAlloca, MismatchedDealloc> MismatchedDeallocatorChecker;
  DynMemFrontend<UseFree> InnerPointerChecker;
  // This last frontend is associated with a single bug type which is not used
  // elsewhere and has a different bug category, so it's declared separately.
  CheckerFrontendWithBugType TaintedAllocChecker{"Tainted Memory Allocation",
                                                 categories::TaintedData};

  using LeakInfo = std::pair<const ExplodedNode *, const MemRegion *>;

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

  ProgramStateRef
  handleSmartPointerConstructorArguments(const CallEvent &Call,
                                         ProgramStateRef State) const;
  ProgramStateRef handleSmartPointerRelatedCalls(const CallEvent &Call,
                                                 CheckerContext &C,
                                                 ProgramStateRef State) const;
  void checkNewAllocator(const CXXAllocatorCall &Call, CheckerContext &C) const;
  void checkPostObjCMessage(const ObjCMethodCall &Call, CheckerContext &C) const;
  void checkPostStmt(const BlockExpr *BE, CheckerContext &C) const;
  void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
  void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const;
  void checkEndFunction(const ReturnStmt *S, CheckerContext &C) const;
  ProgramStateRef evalAssume(ProgramStateRef state, SVal Cond,
                            bool Assumption) const;
  void checkLocation(SVal l, bool isLoad, const Stmt *S,
                     CheckerContext &C) const;

  ProgramStateRef checkPointerEscape(ProgramStateRef State,
                                    const InvalidatedSymbols &Escaped,
                                    const CallEvent *Call,
                                    PointerEscapeKind Kind) const;
  ProgramStateRef checkConstPointerEscape(ProgramStateRef State,
                                          const InvalidatedSymbols &Escaped,
                                          const CallEvent *Call,
                                          PointerEscapeKind Kind) const;

  void printState(raw_ostream &Out, ProgramStateRef State,
                  const char *NL, const char *Sep) const override;

  StringRef getDebugTag() const override { return "MallocChecker"; }

private:
#define CHECK_FN(NAME)                                                         \
  void NAME(ProgramStateRef State, const CallEvent &Call, CheckerContext &C)   \
      const;

  CHECK_FN(checkFree)
  CHECK_FN(checkIfNameIndex)
  CHECK_FN(checkBasicAlloc)
  CHECK_FN(checkKernelMalloc)
  CHECK_FN(checkCalloc)
  CHECK_FN(checkAlloca)
  CHECK_FN(checkStrdup)
  CHECK_FN(checkIfFreeNameIndex)
  CHECK_FN(checkCXXNewOrCXXDelete)
  CHECK_FN(checkGMalloc0)
  CHECK_FN(checkGMemdup)
  CHECK_FN(checkGMallocN)
  CHECK_FN(checkGMallocN0)
  CHECK_FN(preGetDelimOrGetLine)
  CHECK_FN(checkGetDelimOrGetLine)
  CHECK_FN(checkReallocN)
  CHECK_FN(checkOwnershipAttr)

  void checkRealloc(ProgramStateRef State, const CallEvent &Call,
                    CheckerContext &C, bool ShouldFreeOnFail) const;

  using CheckFn =
      std::function<void(const class MallocChecker *, ProgramStateRef State,
                         const CallEvent &Call, CheckerContext &C)>;

  const CallDescriptionMap<CheckFn> PreFnMap{
      // NOTE: the following CallDescription also matches the C++ standard
      // library function std::getline(); the callback will filter it out.
      {{CDM::CLibrary, {"getline"}, 3}, &MallocChecker::preGetDelimOrGetLine},
      {{CDM::CLibrary, {"getdelim"}, 4}, &MallocChecker::preGetDelimOrGetLine},
  };

  const CallDescriptionMap<CheckFn> PostFnMap{
      // NOTE: the following CallDescription also matches the C++ standard
      // library function std::getline(); the callback will filter it out.
      {{CDM::CLibrary, {"getline"}, 3}, &MallocChecker::checkGetDelimOrGetLine},
      {{CDM::CLibrary, {"getdelim"}, 4},
       &MallocChecker::checkGetDelimOrGetLine},
  };

  const CallDescriptionMap<CheckFn> FreeingMemFnMap{
      {{CDM::CLibrary, {"free"}, 1}, &MallocChecker::checkFree},
      {{CDM::CLibrary, {"if_freenameindex"}, 1},
       &MallocChecker::checkIfFreeNameIndex},
      {{CDM::CLibrary, {"kfree"}, 1}, &MallocChecker::checkFree},
      {{CDM::CLibrary, {"g_free"}, 1}, &MallocChecker::checkFree},
  };

  bool isFreeingCall(const CallEvent &Call) const;
  static bool isFreeingOwnershipAttrCall(const FunctionDecl *Func);
  static bool isFreeingOwnershipAttrCall(const CallEvent &Call);
  static bool isAllocatingOwnershipAttrCall(const FunctionDecl *Func);
  static bool isAllocatingOwnershipAttrCall(const CallEvent &Call);

  friend class NoMemOwnershipChangeVisitor;

  CallDescriptionMap<CheckFn> AllocaMemFnMap{
      {{CDM::CLibrary, {"alloca"}, 1}, &MallocChecker::checkAlloca},
      {{CDM::CLibrary, {"_alloca"}, 1}, &MallocChecker::checkAlloca},
      // The line for "alloca" also covers "__builtin_alloca", but the
      // _with_align variant must be listed separately because it takes an
      // extra argument:
      {{CDM::CLibrary, {"__builtin_alloca_with_align"}, 2},
       &MallocChecker::checkAlloca},
  };

  CallDescriptionMap<CheckFn> AllocatingMemFnMap{
      {{CDM::CLibrary, {"malloc"}, 1}, &MallocChecker::checkBasicAlloc},
      {{CDM::CLibrary, {"malloc"}, 3}, &MallocChecker::checkKernelMalloc},
      {{CDM::CLibrary, {"calloc"}, 2}, &MallocChecker::checkCalloc},
      {{CDM::CLibrary, {"valloc"}, 1}, &MallocChecker::checkBasicAlloc},
      {{CDM::CLibrary, {"strndup"}, 2}, &MallocChecker::checkStrdup},
      {{CDM::CLibrary, {"strdup"}, 1}, &MallocChecker::checkStrdup},
      {{CDM::CLibrary, {"_strdup"}, 1}, &MallocChecker::checkStrdup},
      {{CDM::CLibrary, {"kmalloc"}, 2}, &MallocChecker::checkKernelMalloc},
      {{CDM::CLibrary, {"if_nameindex"}, 1}, &MallocChecker::checkIfNameIndex},
      {{CDM::CLibrary, {"wcsdup"}, 1}, &MallocChecker::checkStrdup},
      {{CDM::CLibrary, {"_wcsdup"}, 1}, &MallocChecker::checkStrdup},
      {{CDM::CLibrary, {"g_malloc"}, 1}, &MallocChecker::checkBasicAlloc},
      {{CDM::CLibrary, {"g_malloc0"}, 1}, &MallocChecker::checkGMalloc0},
      {{CDM::CLibrary, {"g_try_malloc"}, 1}, &MallocChecker::checkBasicAlloc},
      {{CDM::CLibrary, {"g_try_malloc0"}, 1}, &MallocChecker::checkGMalloc0},
      {{CDM::CLibrary, {"g_memdup"}, 2}, &MallocChecker::checkGMemdup},
      {{CDM::CLibrary, {"g_malloc_n"}, 2}, &MallocChecker::checkGMallocN},
      {{CDM::CLibrary, {"g_malloc0_n"}, 2}, &MallocChecker::checkGMallocN0},
      {{CDM::CLibrary, {"g_try_malloc_n"}, 2}, &MallocChecker::checkGMallocN},
      {{CDM::CLibrary, {"g_try_malloc0_n"}, 2}, &MallocChecker::checkGMallocN0},
  };

  CallDescriptionMap<CheckFn> ReallocatingMemFnMap{
      {{CDM::CLibrary, {"realloc"}, 2},
       std::bind(&MallocChecker::checkRealloc, _1, _2, _3, _4, false)},
      {{CDM::CLibrary, {"reallocf"}, 2},
       std::bind(&MallocChecker::checkRealloc, _1, _2, _3, _4, true)},
      {{CDM::CLibrary, {"g_realloc"}, 2},
       std::bind(&MallocChecker::checkRealloc, _1, _2, _3, _4, false)},
      {{CDM::CLibrary, {"g_try_realloc"}, 2},
       std::bind(&MallocChecker::checkRealloc, _1, _2, _3, _4, false)},
      {{CDM::CLibrary, {"g_realloc_n"}, 3}, &MallocChecker::checkReallocN},
      {{CDM::CLibrary, {"g_try_realloc_n"}, 3}, &MallocChecker::checkReallocN},
  };

  bool isMemCall(const CallEvent &Call) const;
  bool hasOwnershipReturns(const CallEvent &Call) const;
  bool hasOwnershipTakesHolds(const CallEvent &Call) const;
  void reportTaintBug(StringRef Msg, ProgramStateRef State, CheckerContext &C,
                      llvm::ArrayRef<SymbolRef> TaintedSyms,
                      AllocationFamily Family) const;

  void checkTaintedness(CheckerContext &C, const CallEvent &Call,
                        const SVal SizeSVal, ProgramStateRef State,
                        AllocationFamily Family) const;

  // TODO: Remove mutable by moving the initializtaion to the registry function.
  mutable std::optional<uint64_t> KernelZeroFlagVal;

  using KernelZeroSizePtrValueTy = std::optional<int>;
  /// Store the value of macro called `ZERO_SIZE_PTR`.
  /// The value is initialized at first use, before first use the outer
  /// Optional is empty, afterwards it contains another Optional that indicates
  /// if the macro value could be determined, and if yes the value itself.
  mutable std::optional<KernelZeroSizePtrValueTy> KernelZeroSizePtrValue;

  /// Process C++ operator new()'s allocation, which is the part of C++
  /// new-expression that goes before the constructor.
  [[nodiscard]] ProgramStateRef
  processNewAllocation(const CXXAllocatorCall &Call, CheckerContext &C,
                       AllocationFamily Family) const;

  /// Perform a zero-allocation check.
  ///
  /// \param [in] Call The expression that allocates memory.
  /// \param [in] IndexOfSizeArg Index of the argument that specifies the size
  ///   of the memory that needs to be allocated. E.g. for malloc, this would be
  ///   0.
  /// \param [in] RetVal Specifies the newly allocated pointer value;
  ///   if unspecified, the value of expression \p E is used.
  [[nodiscard]] static ProgramStateRef
  ProcessZeroAllocCheck(CheckerContext &C, const CallEvent &Call,
                        const unsigned IndexOfSizeArg, ProgramStateRef State,
                        std::optional<SVal> RetVal = std::nullopt);

  /// Model functions with the ownership_returns attribute.
  ///
  /// User-defined function may have the ownership_returns attribute, which
  /// annotates that the function returns with an object that was allocated on
  /// the heap, and passes the ownertship to the callee.
  ///
  ///   void __attribute((ownership_returns(malloc, 1))) *my_malloc(size_t);
  ///
  /// It has two parameters:
  ///   - first: name of the resource (e.g. 'malloc')
  ///   - (OPTIONAL) second: size of the allocated region
  ///
  /// \param [in] Call The expression that allocates memory.
  /// \param [in] Att The ownership_returns attribute.
  /// \param [in] State The \c ProgramState right before allocation.
  /// \returns The ProgramState right after allocation.
  [[nodiscard]] ProgramStateRef
  MallocMemReturnsAttr(CheckerContext &C, const CallEvent &Call,
                       const OwnershipAttr *Att, ProgramStateRef State) const;
  /// Models memory allocation.
  ///
  /// \param [in] C Checker context.
  /// \param [in] Call The expression that allocates memory.
  /// \param [in] State The \c ProgramState right before allocation.
  /// \param [in] isAlloca Is the allocation function alloca-like
  /// \returns The ProgramState with returnValue bound
  [[nodiscard]] ProgramStateRef MallocBindRetVal(CheckerContext &C,
                                                 const CallEvent &Call,
                                                 ProgramStateRef State,
                                                 bool isAlloca) const;

  /// Models memory allocation.
  ///
  /// \param [in] Call The expression that allocates memory.
  /// \param [in] SizeEx Size of the memory that needs to be allocated.
  /// \param [in] Init The value the allocated memory needs to be initialized.
  /// with. For example, \c calloc initializes the allocated memory to 0,
  /// malloc leaves it undefined.
  /// \param [in] State The \c ProgramState right before allocation.
  /// \returns The ProgramState right after allocation.
  [[nodiscard]] ProgramStateRef
  MallocMemAux(CheckerContext &C, const CallEvent &Call, const Expr *SizeEx,
               SVal Init, ProgramStateRef State, AllocationFamily Family) const;

  /// Models memory allocation.
  ///
  /// \param [in] Call The expression that allocates memory.
  /// \param [in] Size Size of the memory that needs to be allocated.
  /// \param [in] Init The value the allocated memory needs to be initialized.
  /// with. For example, \c calloc initializes the allocated memory to 0,
  /// malloc leaves it undefined.
  /// \param [in] State The \c ProgramState right before allocation.
  /// \returns The ProgramState right after allocation.
  [[nodiscard]] ProgramStateRef MallocMemAux(CheckerContext &C,
                                             const CallEvent &Call, SVal Size,
                                             SVal Init, ProgramStateRef State,
                                             AllocationFamily Family) const;

  // Check if this malloc() for special flags. At present that means M_ZERO or
  // __GFP_ZERO (in which case, treat it like calloc).
  [[nodiscard]] std::optional<ProgramStateRef>
  performKernelMalloc(const CallEvent &Call, CheckerContext &C,
                      const ProgramStateRef &State) const;

  /// Model functions with the ownership_takes and ownership_holds attributes.
  ///
  /// User-defined function may have the ownership_takes and/or ownership_holds
  /// attributes, which annotates that the function frees the memory passed as a
  /// parameter.
  ///
  ///   void __attribute((ownership_takes(malloc, 1))) my_free(void *);
  ///   void __attribute((ownership_holds(malloc, 1))) my_hold(void *);
  ///
  /// They have two parameters:
  ///   - first: name of the resource (e.g. 'malloc')
  ///   - second: index of the parameter the attribute applies to
  ///
  /// \param [in] Call The expression that frees memory.
  /// \param [in] Att The ownership_takes or ownership_holds attribute.
  /// \param [in] State The \c ProgramState right before allocation.
  /// \returns The ProgramState right after deallocation.
  [[nodiscard]] ProgramStateRef FreeMemAttr(CheckerContext &C,
                                            const CallEvent &Call,
                                            const OwnershipAttr *Att,
                                            ProgramStateRef State) const;

  /// Models memory deallocation.
  ///
  /// \param [in] Call The expression that frees memory.
  /// \param [in] State The \c ProgramState right before allocation.
  /// \param [in] Num Index of the argument that needs to be freed. This is
  ///   normally 0, but for custom free functions it may be different.
  /// \param [in] Hold Whether the parameter at \p Index has the ownership_holds
  ///   attribute.
  /// \param [out] IsKnownToBeAllocated Whether the memory to be freed is known
  ///   to have been allocated, or in other words, the symbol to be freed was
  ///   registered as allocated by this checker. In the following case, \c ptr
  ///   isn't known to be allocated.
  ///      void Haha(int *ptr) {
  ///        ptr = realloc(ptr, 67);
  ///        // ...
  ///      }
  /// \param [in] ReturnsNullOnFailure Whether the memory deallocation function
  ///   we're modeling returns with Null on failure.
  /// \returns The ProgramState right after deallocation.
  [[nodiscard]] ProgramStateRef
  FreeMemAux(CheckerContext &C, const CallEvent &Call, ProgramStateRef State,
             unsigned Num, bool Hold, bool &IsKnownToBeAllocated,
             AllocationFamily Family, bool ReturnsNullOnFailure = false) const;

  /// Models memory deallocation.
  ///
  /// \param [in] ArgExpr The variable who's pointee needs to be freed.
  /// \param [in] Call The expression that frees the memory.
  /// \param [in] State The \c ProgramState right before allocation.
  ///   normally 0, but for custom free functions it may be different.
  /// \param [in] Hold Whether the parameter at \p Index has the ownership_holds
  ///   attribute.
  /// \param [out] IsKnownToBeAllocated Whether the memory to be freed is known
  ///   to have been allocated, or in other words, the symbol to be freed was
  ///   registered as allocated by this checker. In the following case, \c ptr
  ///   isn't known to be allocated.
  ///      void Haha(int *ptr) {
  ///        ptr = realloc(ptr, 67);
  ///        // ...
  ///      }
  /// \param [in] ReturnsNullOnFailure Whether the memory deallocation function
  ///   we're modeling returns with Null on failure.
  /// \param [in] ArgValOpt Optional value to use for the argument instead of
  /// the one obtained from ArgExpr.
  /// \returns The ProgramState right after deallocation.
  [[nodiscard]] ProgramStateRef
  FreeMemAux(CheckerContext &C, const Expr *ArgExpr, const CallEvent &Call,
             ProgramStateRef State, bool Hold, bool &IsKnownToBeAllocated,
             AllocationFamily Family, bool ReturnsNullOnFailure = false,
             std::optional<SVal> ArgValOpt = {}) const;

  // TODO: Needs some refactoring, as all other deallocation modeling
  // functions are suffering from out parameters and messy code due to how
  // realloc is handled.
  //
  /// Models memory reallocation.
  ///
  /// \param [in] Call The expression that reallocated memory
  /// \param [in] ShouldFreeOnFail Whether if reallocation fails, the supplied
  ///   memory should be freed.
  /// \param [in] State The \c ProgramState right before reallocation.
  /// \param [in] SuffixWithN Whether the reallocation function we're modeling
  ///   has an '_n' suffix, such as g_realloc_n.
  /// \returns The ProgramState right after reallocation.
  [[nodiscard]] ProgramStateRef
  ReallocMemAux(CheckerContext &C, const CallEvent &Call, bool ShouldFreeOnFail,
                ProgramStateRef State, AllocationFamily Family,
                bool SuffixWithN = false) const;

  /// Evaluates the buffer size that needs to be allocated.
  ///
  /// \param [in] Blocks The amount of blocks that needs to be allocated.
  /// \param [in] BlockBytes The size of a block.
  /// \returns The symbolic value of \p Blocks * \p BlockBytes.
  [[nodiscard]] static SVal evalMulForBufferSize(CheckerContext &C,
                                                 const Expr *Blocks,
                                                 const Expr *BlockBytes);

  /// Models zero initialized array allocation.
  ///
  /// \param [in] Call The expression that reallocated memory
  /// \param [in] State The \c ProgramState right before reallocation.
  /// \returns The ProgramState right after allocation.
  [[nodiscard]] ProgramStateRef CallocMem(CheckerContext &C,
                                          const CallEvent &Call,
                                          ProgramStateRef State) const;

  /// See if deallocation happens in a suspicious context. If so, escape the
  /// pointers that otherwise would have been deallocated and return true.
  bool suppressDeallocationsInSuspiciousContexts(const CallEvent &Call,
                                                 CheckerContext &C) const;

  /// If in \p S  \p Sym is used, check whether \p Sym was already freed.
  bool checkUseAfterFree(SymbolRef Sym, CheckerContext &C, const Stmt *S) const;

  /// If in \p S \p Sym is used, check whether \p Sym was allocated as a zero
  /// sized memory region.
  void checkUseZeroAllocated(SymbolRef Sym, CheckerContext &C,
                             const Stmt *S) const;

  /// Check if the function is known to free memory, or if it is
  /// "interesting" and should be modeled explicitly.
  ///
  /// \param [out] EscapingSymbol A function might not free memory in general,
  ///   but could be known to free a particular symbol. In this case, false is
  ///   returned and the single escaping symbol is returned through the out
  ///   parameter.
  ///
  /// We assume that pointers do not escape through calls to system functions
  /// not handled by this checker.
  bool mayFreeAnyEscapedMemoryOrIsModeledExplicitly(const CallEvent *Call,
                                   ProgramStateRef State,
                                   SymbolRef &EscapingSymbol) const;

  /// Implementation of the checkPointerEscape callbacks.
  [[nodiscard]] ProgramStateRef
  checkPointerEscapeAux(ProgramStateRef State,
                        const InvalidatedSymbols &Escaped,
                        const CallEvent *Call, PointerEscapeKind Kind,
                        bool IsConstPointerEscape) const;

  // Implementation of the checkPreStmt and checkEndFunction callbacks.
  void checkEscapeOnReturn(const ReturnStmt *S, CheckerContext &C) const;

  ///@{
  /// Returns a pointer to the checker frontend corresponding to the given
  /// family or symbol. The template argument T may be either CheckerFamily or
  /// a BUGTYPE_PROVIDER class; in the latter case the query is restricted to
  /// frontends that descend from that PROVIDER class (i.e. can emit that bug
  /// type). Note that this may return a frontend which is disabled.
  template <class T>
  const T *getRelevantFrontendAs(AllocationFamily Family) const;

  template <class T>
  const T *getRelevantFrontendAs(CheckerContext &C, SymbolRef Sym) const;
  ///@}
  static bool SummarizeValue(raw_ostream &os, SVal V);
  static bool SummarizeRegion(ProgramStateRef State, raw_ostream &os,
                              const MemRegion *MR);

  void HandleNonHeapDealloc(CheckerContext &C, SVal ArgVal, SourceRange Range,
                            const Expr *DeallocExpr,
                            AllocationFamily Family) const;

  void HandleFreeAlloca(CheckerContext &C, SVal ArgVal,
                        SourceRange Range) const;

  void HandleMismatchedDealloc(CheckerContext &C, SourceRange Range,
                               const Expr *DeallocExpr, const RefState *RS,
                               SymbolRef Sym, bool OwnershipTransferred) const;

  void HandleOffsetFree(CheckerContext &C, SVal ArgVal, SourceRange Range,
                        const Expr *DeallocExpr, AllocationFamily Family,
                        const Expr *AllocExpr = nullptr) const;

  void HandleUseAfterFree(CheckerContext &C, SourceRange Range,
                          SymbolRef Sym) const;

  void HandleDoubleFree(CheckerContext &C, SourceRange Range, bool Released,
                        SymbolRef Sym, SymbolRef PrevSym) const;

  void HandleUseZeroAlloc(CheckerContext &C, SourceRange Range,
                          SymbolRef Sym) const;

  void HandleFunctionPtrFree(CheckerContext &C, SVal ArgVal, SourceRange Range,
                             const Expr *FreeExpr,
                             AllocationFamily Family) const;

  /// Find the location of the allocation for Sym on the path leading to the
  /// exploded node N.
  static LeakInfo getAllocationSite(const ExplodedNode *N, SymbolRef Sym,
                                    CheckerContext &C);

  void HandleLeak(SymbolRef Sym, ExplodedNode *N, CheckerContext &C) const;

  /// Test if value in ArgVal equals to value in macro `ZERO_SIZE_PTR`.
  bool isArgZERO_SIZE_PTR(ProgramStateRef State, CheckerContext &C,
                          SVal ArgVal) const;
};
} // end anonymous namespace

//===----------------------------------------------------------------------===//
// Definition of NoOwnershipChangeVisitor.
//===----------------------------------------------------------------------===//

namespace {
class NoMemOwnershipChangeVisitor final : public NoOwnershipChangeVisitor {
protected:
  /// Syntactically checks whether the callee is a deallocating function. Since
  /// we have no path-sensitive information on this call (we would need a
  /// CallEvent instead of a CallExpr for that), its possible that a
  /// deallocation function was called indirectly through a function pointer,
  /// but we are not able to tell, so this is a best effort analysis.
  /// See namespace `memory_passed_to_fn_call_free_through_fn_ptr` in
  /// clang/test/Analysis/NewDeleteLeaks.cpp.
  bool isFreeingCallAsWritten(const CallExpr &Call) const {
    const auto *MallocChk = static_cast<const MallocChecker *>(&Checker);
    if (MallocChk->FreeingMemFnMap.lookupAsWritten(Call) ||
        MallocChk->ReallocatingMemFnMap.lookupAsWritten(Call))
      return true;

    if (const auto *Func =
            llvm::dyn_cast_or_null<FunctionDecl>(Call.getCalleeDecl()))
      return MallocChecker::isFreeingOwnershipAttrCall(Func);

    return false;
  }

  bool hasResourceStateChanged(ProgramStateRef CallEnterState,
                               ProgramStateRef CallExitEndState) final {
    return CallEnterState->get<RegionState>(Sym) !=
           CallExitEndState->get<RegionState>(Sym);
  }

  /// Heuristically guess whether the callee intended to free memory. This is
  /// done syntactically, because we are trying to argue about alternative
  /// paths of execution, and as a consequence we don't have path-sensitive
  /// information.
  bool doesFnIntendToHandleOwnership(const Decl *Callee,
                                     ASTContext &ACtx) final {
    const FunctionDecl *FD = dyn_cast<FunctionDecl>(Callee);

    // Given that the stack frame was entered, the body should always be
    // theoretically obtainable. In case of body farms, the synthesized body
    // is not attached to declaration, thus triggering the '!FD->hasBody()'
    // branch. That said, would a synthesized body ever intend to handle
    // ownership? As of today they don't. And if they did, how would we
    // put notes inside it, given that it doesn't match any source locations?
    if (!FD || !FD->hasBody())
      return false;
    using namespace clang::ast_matchers;

    auto Matches = match(findAll(stmt(anyOf(cxxDeleteExpr().bind("delete"),
                                            callExpr().bind("call")))),
                         *FD->getBody(), ACtx);
    for (BoundNodes Match : Matches) {
      if (Match.getNodeAs<CXXDeleteExpr>("delete"))
        return true;

      if (const auto *Call = Match.getNodeAs<CallExpr>("call"))
        if (isFreeingCallAsWritten(*Call))
          return true;
    }
    // TODO: Ownership might change with an attempt to store the allocated
    // memory, not only through deallocation. Check for attempted stores as
    // well.
    return false;
  }

  PathDiagnosticPieceRef emitNote(const ExplodedNode *N) final {
    PathDiagnosticLocation L = PathDiagnosticLocation::create(
        N->getLocation(),
        N->getState()->getStateManager().getContext().getSourceManager());
    return std::make_shared<PathDiagnosticEventPiece>(
        L, "Returning without deallocating memory or storing the pointer for "
           "later deallocation");
  }

public:
  NoMemOwnershipChangeVisitor(SymbolRef Sym, const MallocChecker *Checker)
      : NoOwnershipChangeVisitor(Sym, Checker) {}

  void Profile(llvm::FoldingSetNodeID &ID) const override {
    static int Tag = 0;
    ID.AddPointer(&Tag);
    ID.AddPointer(Sym);
  }
};

} // end anonymous namespace

//===----------------------------------------------------------------------===//
// Definition of MallocBugVisitor.
//===----------------------------------------------------------------------===//

namespace {
/// The bug visitor which allows us to print extra diagnostics along the
/// BugReport path. For example, showing the allocation site of the leaked
/// region.
class MallocBugVisitor final : public BugReporterVisitor {
protected:
  enum NotificationMode { Normal, ReallocationFailed };

  // The allocated region symbol tracked by the main analysis.
  SymbolRef Sym;

  // The mode we are in, i.e. what kind of diagnostics will be emitted.
  NotificationMode Mode;

  // A symbol from when the primary region should have been reallocated.
  SymbolRef FailedReallocSymbol;

  // A release function stack frame in which memory was released. Used for
  // miscellaneous false positive suppression.
  const StackFrameContext *ReleaseFunctionLC;

  bool IsLeak;

public:
  MallocBugVisitor(SymbolRef S, bool isLeak = false)
      : Sym(S), Mode(Normal), FailedReallocSymbol(nullptr),
        ReleaseFunctionLC(nullptr), IsLeak(isLeak) {}

  static void *getTag() {
    static int Tag = 0;
    return &Tag;
  }

  void Profile(llvm::FoldingSetNodeID &ID) const override {
    ID.AddPointer(getTag());
    ID.AddPointer(Sym);
  }

  /// Did not track -> allocated. Other state (released) -> allocated.
  static inline bool isAllocated(const RefState *RSCurr, const RefState *RSPrev,
                                 const Stmt *Stmt) {
    return (isa_and_nonnull<CallExpr, CXXNewExpr>(Stmt) &&
            (RSCurr &&
             (RSCurr->isAllocated() || RSCurr->isAllocatedOfSizeZero())) &&
            (!RSPrev ||
             !(RSPrev->isAllocated() || RSPrev->isAllocatedOfSizeZero())));
  }

  /// Did not track -> released. Other state (allocated) -> released.
  /// The statement associated with the release might be missing.
  static inline bool isReleased(const RefState *RSCurr, const RefState *RSPrev,
                                const Stmt *Stmt) {
    bool IsReleased =
        (RSCurr && RSCurr->isReleased()) && (!RSPrev || !RSPrev->isReleased());
    assert(!IsReleased || (isa_and_nonnull<CallExpr, CXXDeleteExpr>(Stmt)) ||
           (!Stmt && RSCurr->getAllocationFamily().Kind == AF_InnerBuffer));
    return IsReleased;
  }

  /// Did not track -> relinquished. Other state (allocated) -> relinquished.
  static inline bool isRelinquished(const RefState *RSCurr,
                                    const RefState *RSPrev, const Stmt *Stmt) {
    return (
        isa_and_nonnull<CallExpr, ObjCMessageExpr, ObjCPropertyRefExpr>(Stmt) &&
        (RSCurr && RSCurr->isRelinquished()) &&
        (!RSPrev || !RSPrev->isRelinquished()));
  }

  /// If the expression is not a call, and the state change is
  /// released -> allocated, it must be the realloc return value
  /// check. If we have to handle more cases here, it might be cleaner just
  /// to track this extra bit in the state itself.
  static inline bool hasReallocFailed(const RefState *RSCurr,
                                      const RefState *RSPrev,
                                      const Stmt *Stmt) {
    return ((!isa_and_nonnull<CallExpr>(Stmt)) &&
            (RSCurr &&
             (RSCurr->isAllocated() || RSCurr->isAllocatedOfSizeZero())) &&
            (RSPrev &&
             !(RSPrev->isAllocated() || RSPrev->isAllocatedOfSizeZero())));
  }

  PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
                                   BugReporterContext &BRC,
                                   PathSensitiveBugReport &BR) override;

  PathDiagnosticPieceRef getEndPath(BugReporterContext &BRC,
                                    const ExplodedNode *EndPathNode,
                                    PathSensitiveBugReport &BR) override {
    if (!IsLeak)
      return nullptr;

    PathDiagnosticLocation L = BR.getLocation();
    // Do not add the statement itself as a range in case of leak.
    return std::make_shared<PathDiagnosticEventPiece>(L, BR.getDescription(),
                                                      false);
  }

private:
  class StackHintGeneratorForReallocationFailed
      : public StackHintGeneratorForSymbol {
  public:
    StackHintGeneratorForReallocationFailed(SymbolRef S, StringRef M)
        : StackHintGeneratorForSymbol(S, M) {}

    std::string getMessageForArg(const Expr *ArgE, unsigned ArgIndex) override {
      // Printed parameters start at 1, not 0.
      ++ArgIndex;

      SmallString<200> buf;
      llvm::raw_svector_ostream os(buf);

      os << "Reallocation of " << ArgIndex << llvm::getOrdinalSuffix(ArgIndex)
         << " parameter failed";

      return std::string(os.str());
    }

    std::string getMessageForReturn(const CallExpr *CallExpr) override {
      return "Reallocation of returned value failed";
    }
  };
};
} // end anonymous namespace

// A map from the freed symbol to the symbol representing the return value of
// the free function.
REGISTER_MAP_WITH_PROGRAMSTATE(FreeReturnValue, SymbolRef, SymbolRef)

namespace {
class StopTrackingCallback final : public SymbolVisitor {
  ProgramStateRef state;

public:
  StopTrackingCallback(ProgramStateRef st) : state(std::move(st)) {}
  ProgramStateRef getState() const { return state; }

  bool VisitSymbol(SymbolRef sym) override {
    state = state->remove<RegionState>(sym);
    return true;
  }
};

/// EscapeTrackedCallback - A SymbolVisitor that marks allocated symbols as
/// escaped.
///
/// This visitor is used to suppress false positive leak reports when smart
/// pointers are nested in temporary objects passed by value to functions. When
/// the analyzer can't see the destructor calls for temporary objects, it may
/// incorrectly report leaks for memory that will be properly freed by the smart
/// pointer destructors.
///
/// The visitor traverses reachable symbols from a given set of memory regions
/// (typically smart pointer field regions) and marks any allocated symbols as
/// escaped. Escaped symbols are not reported as leaks by checkDeadSymbols.
class EscapeTrackedCallback final : public SymbolVisitor {
  ProgramStateRef State;

  explicit EscapeTrackedCallback(ProgramStateRef S) : State(std::move(S)) {}

public:
  bool VisitSymbol(SymbolRef Sym) override {
    if (const RefState *RS = State->get<RegionState>(Sym)) {
      if (RS->isAllocated() || RS->isAllocatedOfSizeZero()) {
        State = State->set<RegionState>(Sym, RefState::getEscaped(RS));
      }
    }
    return true;
  }

  /// Escape tracked regions reachable from the given roots.
  static ProgramStateRef
  EscapeTrackedRegionsReachableFrom(ArrayRef<const MemRegion *> Roots,
                                    ProgramStateRef State) {
    if (Roots.empty())
      return State;

    // scanReachableSymbols is expensive, so we use a single visitor for all
    // roots
    SmallVector<const MemRegion *, 10> Regions;
    EscapeTrackedCallback Visitor(State);
    for (const MemRegion *R : Roots) {
      Regions.push_back(R);
    }
    State->scanReachableSymbols(Regions, Visitor);
    return Visitor.State;
  }

  friend class SymbolVisitor;
};
} // end anonymous namespace

static bool isStandardNew(const FunctionDecl *FD) {
  if (!FD)
    return false;

  OverloadedOperatorKind Kind = FD->getOverloadedOperator();
  if (Kind != OO_New && Kind != OO_Array_New)
    return false;

  // This is standard if and only if it's not defined in a user file.
  SourceLocation L = FD->getLocation();
  // If the header for operator delete is not included, it's still defined
  // in an invalid source location. Check to make sure we don't crash.
  return !L.isValid() ||
         FD->getASTContext().getSourceManager().isInSystemHeader(L);
}

static bool isStandardDelete(const FunctionDecl *FD) {
  if (!FD)
    return false;

  OverloadedOperatorKind Kind = FD->getOverloadedOperator();
  if (Kind != OO_Delete && Kind != OO_Array_Delete)
    return false;

  bool HasBody = FD->hasBody(); // Prefer using the definition.

  // This is standard if and only if it's not defined in a user file.
  SourceLocation L = FD->getLocation();

  // If the header for operator delete is not included, it's still defined
  // in an invalid source location. Check to make sure we don't crash.
  const auto &SM = FD->getASTContext().getSourceManager();
  return L.isInvalid() || (!HasBody && SM.isInSystemHeader(L));
}

//===----------------------------------------------------------------------===//
// Methods of MallocChecker and MallocBugVisitor.
//===----------------------------------------------------------------------===//

bool MallocChecker::isFreeingOwnershipAttrCall(const CallEvent &Call) {
  const auto *Func = dyn_cast_or_null<FunctionDecl>(Call.getDecl());

  return Func && isFreeingOwnershipAttrCall(Func);
}

bool MallocChecker::isFreeingOwnershipAttrCall(const FunctionDecl *Func) {
  if (Func->hasAttrs()) {
    for (const auto *I : Func->specific_attrs<OwnershipAttr>()) {
      OwnershipAttr::OwnershipKind OwnKind = I->getOwnKind();
      if (OwnKind == OwnershipAttr::Takes || OwnKind == OwnershipAttr::Holds)
        return true;
    }
  }
  return false;
}

bool MallocChecker::isFreeingCall(const CallEvent &Call) const {
  if (FreeingMemFnMap.lookup(Call) || ReallocatingMemFnMap.lookup(Call))
    return true;

  return isFreeingOwnershipAttrCall(Call);
}

bool MallocChecker::isAllocatingOwnershipAttrCall(const CallEvent &Call) {
  const auto *Func = dyn_cast_or_null<FunctionDecl>(Call.getDecl());

  return Func && isAllocatingOwnershipAttrCall(Func);
}

bool MallocChecker::isAllocatingOwnershipAttrCall(const FunctionDecl *Func) {
  for (const auto *I : Func->specific_attrs<OwnershipAttr>()) {
    if (I->getOwnKind() == OwnershipAttr::Returns)
      return true;
  }

  return false;
}

bool MallocChecker::isMemCall(const CallEvent &Call) const {
  if (FreeingMemFnMap.lookup(Call) || AllocatingMemFnMap.lookup(Call) ||
      AllocaMemFnMap.lookup(Call) || ReallocatingMemFnMap.lookup(Call))
    return true;

  if (!ShouldIncludeOwnershipAnnotatedFunctions)
    return false;

  const auto *Func = dyn_cast<FunctionDecl>(Call.getDecl());
  return Func && Func->hasAttr<OwnershipAttr>();
}

std::optional<ProgramStateRef>
MallocChecker::performKernelMalloc(const CallEvent &Call, CheckerContext &C,
                                   const ProgramStateRef &State) const {
  // 3-argument malloc(), as commonly used in {Free,Net,Open}BSD Kernels:
  //
  // void *malloc(unsigned long size, struct malloc_type *mtp, int flags);
  //
  // One of the possible flags is M_ZERO, which means 'give me back an
  // allocation which is already zeroed', like calloc.

  // 2-argument kmalloc(), as used in the Linux kernel:
  //
  // void *kmalloc(size_t size, gfp_t flags);
  //
  // Has the similar flag value __GFP_ZERO.

  // This logic is largely cloned from O_CREAT in UnixAPIChecker, maybe some
  // code could be shared.

  ASTContext &Ctx = C.getASTContext();
  llvm::Triple::OSType OS = Ctx.getTargetInfo().getTriple().getOS();

  if (!KernelZeroFlagVal) {
    switch (OS) {
    case llvm::Triple::FreeBSD:
      KernelZeroFlagVal = 0x0100;
      break;
    case llvm::Triple::NetBSD:
      KernelZeroFlagVal = 0x0002;
      break;
    case llvm::Triple::OpenBSD:
      KernelZeroFlagVal = 0x0008;
      break;
    case llvm::Triple::Linux:
      // __GFP_ZERO
      KernelZeroFlagVal = 0x8000;
      break;
    default:
      // FIXME: We need a more general way of getting the M_ZERO value.
      // See also: O_CREAT in UnixAPIChecker.cpp.

      // Fall back to normal malloc behavior on platforms where we don't
      // know M_ZERO.
      return std::nullopt;
    }
  }

  // We treat the last argument as the flags argument, and callers fall-back to
  // normal malloc on a None return. This works for the FreeBSD kernel malloc
  // as well as Linux kmalloc.
  if (Call.getNumArgs() < 2)
    return std::nullopt;

  const Expr *FlagsEx = Call.getArgExpr(Call.getNumArgs() - 1);
  const SVal V = C.getSVal(FlagsEx);
  if (!isa<NonLoc>(V)) {
    // The case where 'V' can be a location can only be due to a bad header,
    // so in this case bail out.
    return std::nullopt;
  }

  NonLoc Flags = V.castAs<NonLoc>();
  NonLoc ZeroFlag = C.getSValBuilder()
                        .makeIntVal(*KernelZeroFlagVal, FlagsEx->getType())
                        .castAs<NonLoc>();
  SVal MaskedFlagsUC = C.getSValBuilder().evalBinOpNN(State, BO_And,
                                                      Flags, ZeroFlag,
                                                      FlagsEx->getType());
  if (MaskedFlagsUC.isUnknownOrUndef())
    return std::nullopt;
  DefinedSVal MaskedFlags = MaskedFlagsUC.castAs<DefinedSVal>();

  // Check if maskedFlags is non-zero.
  ProgramStateRef TrueState, FalseState;
  std::tie(TrueState, FalseState) = State->assume(MaskedFlags);

  // If M_ZERO is set, treat this like calloc (initialized).
  if (TrueState && !FalseState) {
    SVal ZeroVal = C.getSValBuilder().makeZeroVal(Ctx.CharTy);
    return MallocMemAux(C, Call, Call.getArgExpr(0), ZeroVal, TrueState,
                        AllocationFamily(AF_Malloc));
  }

  return std::nullopt;
}

SVal MallocChecker::evalMulForBufferSize(CheckerContext &C, const Expr *Blocks,
                                         const Expr *BlockBytes) {
  SValBuilder &SB = C.getSValBuilder();
  SVal BlocksVal = C.getSVal(Blocks);
  SVal BlockBytesVal = C.getSVal(BlockBytes);
  ProgramStateRef State = C.getState();
  SVal TotalSize = SB.evalBinOp(State, BO_Mul, BlocksVal, BlockBytesVal,
                                SB.getContext().getCanonicalSizeType());
  return TotalSize;
}

void MallocChecker::checkBasicAlloc(ProgramStateRef State,
                                    const CallEvent &Call,
                                    CheckerContext &C) const {
  State = MallocMemAux(C, Call, Call.getArgExpr(0), UndefinedVal(), State,
                       AllocationFamily(AF_Malloc));
  State = ProcessZeroAllocCheck(C, Call, 0, State);
  C.addTransition(State);
}

void MallocChecker::checkKernelMalloc(ProgramStateRef State,
                                      const CallEvent &Call,
                                      CheckerContext &C) const {
  std::optional<ProgramStateRef> MaybeState =
      performKernelMalloc(Call, C, State);
  if (MaybeState)
    State = *MaybeState;
  else
    State = MallocMemAux(C, Call, Call.getArgExpr(0), UndefinedVal(), State,
                         AllocationFamily(AF_Malloc));
  C.addTransition(State);
}

static bool isStandardRealloc(const CallEvent &Call) {
  const FunctionDecl *FD = dyn_cast<FunctionDecl>(Call.getDecl());
  assert(FD);
  ASTContext &AC = FD->getASTContext();
  return AC.hasSameType(FD->getDeclaredReturnType(), AC.VoidPtrTy) &&
         AC.hasSameType(FD->getParamDecl(0)->getType(), AC.VoidPtrTy) &&
         AC.hasSameType(FD->getParamDecl(1)->getType(), AC.getSizeType());
}

static bool isGRealloc(const CallEvent &Call) {
  const FunctionDecl *FD = dyn_cast<FunctionDecl>(Call.getDecl());
  assert(FD);
  ASTContext &AC = FD->getASTContext();

  return AC.hasSameType(FD->getDeclaredReturnType(), AC.VoidPtrTy) &&
         AC.hasSameType(FD->getParamDecl(0)->getType(), AC.VoidPtrTy) &&
         AC.hasSameType(FD->getParamDecl(1)->getType(), AC.UnsignedLongTy);
}

void MallocChecker::checkRealloc(ProgramStateRef State, const CallEvent &Call,
                                 CheckerContext &C,
                                 bool ShouldFreeOnFail) const {
  // Ignore calls to functions whose type does not match the expected type of
  // either the standard realloc or g_realloc from GLib.
  // FIXME: Should we perform this kind of checking consistently for each
  // function? If yes, then perhaps extend the `CallDescription` interface to
  // handle this.
  if (!isStandardRealloc(Call) && !isGRealloc(Call))
    return;

  State = ReallocMemAux(C, Call, ShouldFreeOnFail, State,
                        AllocationFamily(AF_Malloc));
  State = ProcessZeroAllocCheck(C, Call, 1, State);
  C.addTransition(State);
}

void MallocChecker::checkCalloc(ProgramStateRef State, const CallEvent &Call,
                                CheckerContext &C) const {
  State = CallocMem(C, Call, State);
  State = ProcessZeroAllocCheck(C, Call, 0, State);
  State = ProcessZeroAllocCheck(C, Call, 1, State);
  C.addTransition(State);
}

void MallocChecker::checkFree(ProgramStateRef State, const CallEvent &Call,
                              CheckerContext &C) const {
  bool IsKnownToBeAllocatedMemory = false;
  if (suppressDeallocationsInSuspiciousContexts(Call, C))
    return;
  State = FreeMemAux(C, Call, State, 0, false, IsKnownToBeAllocatedMemory,
                     AllocationFamily(AF_Malloc));
  C.addTransition(State);
}

void MallocChecker::checkAlloca(ProgramStateRef State, const CallEvent &Call,
                                CheckerContext &C) const {
  State = MallocMemAux(C, Call, Call.getArgExpr(0), UndefinedVal(), State,
                       AllocationFamily(AF_Alloca));
  State = ProcessZeroAllocCheck(C, Call, 0, State);
  C.addTransition(State);
}

void MallocChecker::checkStrdup(ProgramStateRef State, const CallEvent &Call,
                                CheckerContext &C) const {
  const auto *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
    return;
  State = MallocMemAux(C, Call, UnknownVal(), UnknownVal(), State,
                       AllocationFamily(AF_Malloc));

  C.addTransition(State);
}

void MallocChecker::checkIfNameIndex(ProgramStateRef State,
                                     const CallEvent &Call,
                                     CheckerContext &C) const {
  // Should we model this differently? We can allocate a fixed number of
  // elements with zeros in the last one.
  State = MallocMemAux(C, Call, UnknownVal(), UnknownVal(), State,
                       AllocationFamily(AF_IfNameIndex));

  C.addTransition(State);
}

void MallocChecker::checkIfFreeNameIndex(ProgramStateRef State,
                                         const CallEvent &Call,
                                         CheckerContext &C) const {
  bool IsKnownToBeAllocatedMemory = false;
  State = FreeMemAux(C, Call, State, 0, false, IsKnownToBeAllocatedMemory,
                     AllocationFamily(AF_IfNameIndex));
  C.addTransition(State);
}

static const Expr *getPlacementNewBufferArg(const CallExpr *CE,
                                            const FunctionDecl *FD) {
  // Checking for signature:
  // void* operator new  ( std::size_t count, void* ptr );
  // void* operator new[]( std::size_t count, void* ptr );
  if (CE->getNumArgs() != 2 || (FD->getOverloadedOperator() != OO_New &&
                                FD->getOverloadedOperator() != OO_Array_New))
    return nullptr;
  auto BuffType = FD->getParamDecl(1)->getType();
  if (BuffType.isNull() || !BuffType->isVoidPointerType())
    return nullptr;
  return CE->getArg(1);
}

void MallocChecker::checkCXXNewOrCXXDelete(ProgramStateRef State,
                                           const CallEvent &Call,
                                           CheckerContext &C) const {
  bool IsKnownToBeAllocatedMemory = false;
  const auto *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
    return;

  assert(isStandardNewDelete(Call));

  // Process direct calls to operator new/new[]/delete/delete[] functions
  // as distinct from new/new[]/delete/delete[] expressions that are
  // processed by the checkPostStmt callbacks for CXXNewExpr and
  // CXXDeleteExpr.
  const FunctionDecl *FD = C.getCalleeDecl(CE);
  if (const auto *BufArg = getPlacementNewBufferArg(CE, FD)) {
    // Placement new does not allocate memory
    auto RetVal = State->getSVal(BufArg, Call.getLocationContext());
    State = State->BindExpr(CE, C.getLocationContext(), RetVal);
    C.addTransition(State);
    return;
  }

  switch (FD->getOverloadedOperator()) {
  case OO_New:
    State = MallocMemAux(C, Call, CE->getArg(0), UndefinedVal(), State,
                         AllocationFamily(AF_CXXNew));
    State = ProcessZeroAllocCheck(C, Call, 0, State);
    break;
  case OO_Array_New:
    State = MallocMemAux(C, Call, CE->getArg(0), UndefinedVal(), State,
                         AllocationFamily(AF_CXXNewArray));
    State = ProcessZeroAllocCheck(C, Call, 0, State);
    break;
  case OO_Delete:
    State = FreeMemAux(C, Call, State, 0, false, IsKnownToBeAllocatedMemory,
                       AllocationFamily(AF_CXXNew));
    break;
  case OO_Array_Delete:
    State = FreeMemAux(C, Call, State, 0, false, IsKnownToBeAllocatedMemory,
                       AllocationFamily(AF_CXXNewArray));
    break;
  default:
    assert(false && "not a new/delete operator");
    return;
  }

  C.addTransition(State);
}

void MallocChecker::checkGMalloc0(ProgramStateRef State, const CallEvent &Call,
                                  CheckerContext &C) const {
  SValBuilder &svalBuilder = C.getSValBuilder();
  SVal zeroVal = svalBuilder.makeZeroVal(svalBuilder.getContext().CharTy);
  State = MallocMemAux(C, Call, Call.getArgExpr(0), zeroVal, State,
                       AllocationFamily(AF_Malloc));
  State = ProcessZeroAllocCheck(C, Call, 0, State);
  C.addTransition(State);
}

void MallocChecker::checkGMemdup(ProgramStateRef State, const CallEvent &Call,
                                 CheckerContext &C) const {
  State = MallocMemAux(C, Call, Call.getArgExpr(1), UnknownVal(), State,
                       AllocationFamily(AF_Malloc));
  State = ProcessZeroAllocCheck(C, Call, 1, State);
  C.addTransition(State);
}

void MallocChecker::checkGMallocN(ProgramStateRef State, const CallEvent &Call,
                                  CheckerContext &C) const {
  SVal Init = UndefinedVal();
  SVal TotalSize = evalMulForBufferSize(C, Call.getArgExpr(0), Call.getArgExpr(1));
  State = MallocMemAux(C, Call, TotalSize, Init, State,
                       AllocationFamily(AF_Malloc));
  State = ProcessZeroAllocCheck(C, Call, 0, State);
  State = ProcessZeroAllocCheck(C, Call, 1, State);
  C.addTransition(State);
}

void MallocChecker::checkGMallocN0(ProgramStateRef State, const CallEvent &Call,
                                   CheckerContext &C) const {
  SValBuilder &SB = C.getSValBuilder();
  SVal Init = SB.makeZeroVal(SB.getContext().CharTy);
  SVal TotalSize = evalMulForBufferSize(C, Call.getArgExpr(0), Call.getArgExpr(1));
  State = MallocMemAux(C, Call, TotalSize, Init, State,
                       AllocationFamily(AF_Malloc));
  State = ProcessZeroAllocCheck(C, Call, 0, State);
  State = ProcessZeroAllocCheck(C, Call, 1, State);
  C.addTransition(State);
}

static bool isFromStdNamespace(const CallEvent &Call) {
  const Decl *FD = Call.getDecl();
  assert(FD && "a CallDescription cannot match a call without a Decl");
  return FD->isInStdNamespace();
}

void MallocChecker::preGetDelimOrGetLine(ProgramStateRef State,
                                         const CallEvent &Call,
                                         CheckerContext &C) const {
  // Discard calls to the C++ standard library function std::getline(), which
  // is completely unrelated to the POSIX getline() that we're checking.
  if (isFromStdNamespace(Call))
    return;

  const auto LinePtr = getPointeeVal(Call.getArgSVal(0), State);
  if (!LinePtr)
    return;

  // FreeMemAux takes IsKnownToBeAllocated as an output parameter, and it will
  // be true after the call if the symbol was registered by this checker.
  // We do not need this value here, as FreeMemAux will take care
  // of reporting any violation of the preconditions.
  bool IsKnownToBeAllocated = false;
  State = FreeMemAux(C, Call.getArgExpr(0), Call, State, false,
                     IsKnownToBeAllocated, AllocationFamily(AF_Malloc), false,
                     LinePtr);
  if (State)
    C.addTransition(State);
}

void MallocChecker::checkGetDelimOrGetLine(ProgramStateRef State,
                                           const CallEvent &Call,
                                           CheckerContext &C) const {
  // Discard calls to the C++ standard library function std::getline(), which
  // is completely unrelated to the POSIX getline() that we're checking.
  if (isFromStdNamespace(Call))
    return;

  // Handle the post-conditions of getline and getdelim:
  // Register the new conjured value as an allocated buffer.
  const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
    return;

  const auto LinePtrOpt = getPointeeVal(Call.getArgSVal(0), State);
  const auto SizeOpt = getPointeeVal(Call.getArgSVal(1), State);
  if (!LinePtrOpt || !SizeOpt || LinePtrOpt->isUnknownOrUndef() ||
      SizeOpt->isUnknownOrUndef())
    return;

  const auto LinePtr = LinePtrOpt->getAs<DefinedSVal>();
  const auto Size = SizeOpt->getAs<DefinedSVal>();
  const MemRegion *LinePtrReg = LinePtr->getAsRegion();
  if (!LinePtrReg)
    return;

  State = setDynamicExtent(State, LinePtrReg, *Size);
  C.addTransition(MallocUpdateRefState(C, CE, State,
                                       AllocationFamily(AF_Malloc), *LinePtr));
}

void MallocChecker::checkReallocN(ProgramStateRef State, const CallEvent &Call,
                                  CheckerContext &C) const {
  State = ReallocMemAux(C, Call, /*ShouldFreeOnFail=*/false, State,
                        AllocationFamily(AF_Malloc),
                        /*SuffixWithN=*/true);
  State = ProcessZeroAllocCheck(C, Call, 1, State);
  State = ProcessZeroAllocCheck(C, Call, 2, State);
  C.addTransition(State);
}

void MallocChecker::checkOwnershipAttr(ProgramStateRef State,
                                       const CallEvent &Call,
                                       CheckerContext &C) const {
  const auto *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
  if (!CE)
    return;
  const FunctionDecl *FD = C.getCalleeDecl(CE);
  if (!FD)
    return;
  if (ShouldIncludeOwnershipAnnotatedFunctions ||
      MismatchedDeallocatorChecker.isEnabled()) {
    // Check all the attributes, if there are any.
    // There can be multiple of these attributes.
    if (FD->hasAttrs())
      for (const auto *I : FD->specific_attrs<OwnershipAttr>()) {
        switch (I->getOwnKind()) {
        case OwnershipAttr::Returns:
          State = MallocMemReturnsAttr(C, Call, I, State);
          break;
        case OwnershipAttr::Takes:
        case OwnershipAttr::Holds:
          State = FreeMemAttr(C, Call, I, State);
          break;
        }
      }
  }
  C.addTransition(State);
}

bool MallocChecker::evalCall(const CallEvent &Call, CheckerContext &C) const {
  if (!Call.getOriginExpr())
    return false;

  ProgramStateRef State = C.getState();

  if (const CheckFn *Callback = FreeingMemFnMap.lookup(Call)) {
    (*Callback)(this, State, Call, C);
    return true;
  }

  if (const CheckFn *Callback = AllocatingMemFnMap.lookup(Call)) {
    State = MallocBindRetVal(C, Call, State, false);
    (*Callback)(this, State, Call, C);
    return true;
  }

  if (const CheckFn *Callback = ReallocatingMemFnMap.lookup(Call)) {
    State = MallocBindRetVal(C, Call, State, false);
    (*Callback)(this, State, Call, C);
    return true;
  }

  if (isStandardNew(Call)) {
    State = MallocBindRetVal(C, Call, State, false);
    checkCXXNewOrCXXDelete(State, Call, C);
    return true;
  }

  if (isStandardDelete(Call)) {
    checkCXXNewOrCXXDelete(State, Call, C);
    return true;
  }

  if (const CheckFn *Callback = AllocaMemFnMap.lookup(Call)) {
    State = MallocBindRetVal(C, Call, State, true);
    (*Callback)(this, State, Call, C);
    return true;
  }

  if (isFreeingOwnershipAttrCall(Call)) {
    checkOwnershipAttr(State, Call, C);
    return true;
  }

  if (isAllocatingOwnershipAttrCall(Call)) {
    State = MallocBindRetVal(C, Call, State, false);
    checkOwnershipAttr(State, Call, C);
    return true;
  }

  return false;
}

// Performs a 0-sized allocations check.
ProgramStateRef MallocChecker::ProcessZeroAllocCheck(
    CheckerContext &C, const CallEvent &Call, const unsigned IndexOfSizeArg,
    ProgramStateRef State, std::optional<SVal> RetVal) {
  if (!State)
    return nullptr;

  const Expr *Arg = nullptr;

  if (const CallExpr *CE = dyn_cast<CallExpr>(Call.getOriginExpr())) {
    Arg = CE->getArg(IndexOfSizeArg);
  } else if (const CXXNewExpr *NE =
                 dyn_cast<CXXNewExpr>(Call.getOriginExpr())) {
    if (NE->isArray()) {
      Arg = *NE->getArraySize();
    } else {
      return State;
    }
  } else {
    assert(false && "not a CallExpr or CXXNewExpr");
    return nullptr;
  }

  if (!RetVal)
    RetVal = State->getSVal(Call.getOriginExpr(), C.getLocationContext());

  assert(Arg);

  auto DefArgVal =
      State->getSVal(Arg, Call.getLocationContext()).getAs<DefinedSVal>();

  if (!DefArgVal)
    return State;

  // Check if the allocation size is 0.
  ProgramStateRef TrueState, FalseState;
  SValBuilder &SvalBuilder = State->getStateManager().getSValBuilder();
  DefinedSVal Zero =
      SvalBuilder.makeZeroVal(Arg->getType()).castAs<DefinedSVal>();

  std::tie(TrueState, FalseState) =
      State->assume(SvalBuilder.evalEQ(State, *DefArgVal, Zero));

  if (TrueState && !FalseState) {
    SymbolRef Sym = RetVal->getAsLocSymbol();
    if (!Sym)
      return State;

    const RefState *RS = State->get<RegionState>(Sym);
    if (RS) {
      if (RS->isAllocated())
        return TrueState->set<RegionState>(
            Sym, RefState::getAllocatedOfSizeZero(RS));
      return State;
    }
    // Case of zero-size realloc. Historically 'realloc(ptr, 0)' is treated as
    // 'free(ptr)' and the returned value from 'realloc(ptr, 0)' is not
    // tracked. Add zero-reallocated Sym to the state to catch references
    // to zero-allocated memory.
    return TrueState->add<ReallocSizeZeroSymbols>(Sym);
  }

  // Assume the value is non-zero going forward.
  assert(FalseState);
  return FalseState;
}

static QualType getDeepPointeeType(QualType T) {
  QualType Result = T, PointeeType = T->getPointeeType();
  while (!PointeeType.isNull()) {
    Result = PointeeType;
    PointeeType = PointeeType->getPointeeType();
  }
  return Result;
}

/// \returns true if the constructor invoked by \p NE has an argument of a
/// pointer/reference to a record type.
static bool hasNonTrivialConstructorCall(const CXXNewExpr *NE) {

  const CXXConstructExpr *ConstructE = NE->getConstructExpr();
  if (!ConstructE)
    return false;

  if (!NE->getAllocatedType()->getAsCXXRecordDecl())
    return false;

  const CXXConstructorDecl *CtorD = ConstructE->getConstructor();

  // Iterate over the constructor parameters.
  for (const auto *CtorParam : CtorD->parameters()) {

    QualType CtorParamPointeeT = CtorParam->getType()->getPointeeType();
    if (CtorParamPointeeT.isNull())
      continue;

    CtorParamPointeeT = getDeepPointeeType(CtorParamPointeeT);

    if (CtorParamPointeeT->getAsCXXRecordDecl())
      return true;
  }

  return false;
}

ProgramStateRef
MallocChecker::processNewAllocation(const CXXAllocatorCall &Call,
                                    CheckerContext &C,
                                    AllocationFamily Family) const {
  if (!isStandardNewDelete(Call))
    return nullptr;

  const CXXNewExpr *NE = Call.getOriginExpr();
  const ParentMap &PM = C.getLocationContext()->getParentMap();
  ProgramStateRef State = C.getState();

  // Non-trivial constructors have a chance to escape 'this', but marking all
  // invocations of trivial constructors as escaped would cause too great of
  // reduction of true positives, so let's just do that for constructors that
  // have an argument of a pointer-to-record type.
  if (!PM.isConsumedExpr(NE) && hasNonTrivialConstructorCall(NE))
    return State;

  // The return value from operator new is bound to a specified initialization
  // value (if any) and we don't want to loose this value. So we call
  // MallocUpdateRefState() instead of MallocMemAux() which breaks the
  // existing binding.
  SVal Target = Call.getObjectUnderConstruction();
  if (Call.getOriginExpr()->isArray()) {
    if (auto SizeEx = NE->getArraySize())
      checkTaintedness(C, Call, C.getSVal(*SizeEx), State,
                       AllocationFamily(AF_CXXNewArray));
  }

  State = MallocUpdateRefState(C, NE, State, Family, Target);
  State = ProcessZeroAllocCheck(C, Call, 0, State, Target);
  return State;
}

void MallocChecker::checkNewAllocator(const CXXAllocatorCall &Call,
                                      CheckerContext &C) const {
  if (!C.wasInlined) {
    ProgramStateRef State = processNewAllocation(
        Call, C,
        AllocationFamily(Call.getOriginExpr()->isArray() ? AF_CXXNewArray
                                                         : AF_CXXNew));
    C.addTransition(State);
  }
}

static bool isKnownDeallocObjCMethodName(const ObjCMethodCall &Call) {
  // If the first selector piece is one of the names below, assume that the
  // object takes ownership of the memory, promising to eventually deallocate it
  // with free().
  // Ex:  [NSData dataWithBytesNoCopy:bytes length:10];
  // (...unless a 'freeWhenDone' parameter is false, but that's checked later.)
  StringRef FirstSlot = Call.getSelector().getNameForSlot(0);
  return FirstSlot == "dataWithBytesNoCopy" ||
         FirstSlot == "initWithBytesNoCopy" ||
         FirstSlot == "initWithCharactersNoCopy";
}

static std::optional<bool> getFreeWhenDoneArg(const ObjCMethodCall &Call) {
  Selector S = Call.getSelector();

  // FIXME: We should not rely on fully-constrained symbols being folded.
  for (unsigned i = 1; i < S.getNumArgs(); ++i)
    if (S.getNameForSlot(i) == "freeWhenDone")
      return !Call.getArgSVal(i).isZeroConstant();

  return std::nullopt;
}

void MallocChecker::checkPostObjCMessage(const ObjCMethodCall &Call,
                                         CheckerContext &C) const {
  if (C.wasInlined)
    return;

  if (!isKnownDeallocObjCMethodName(Call))
    return;

  if (std::optional<bool> FreeWhenDone = getFreeWhenDoneArg(Call))
    if (!*FreeWhenDone)
      return;

  if (Call.hasNonZeroCallbackArg())
    return;

  bool IsKnownToBeAllocatedMemory;
  ProgramStateRef State = FreeMemAux(C, Call.getArgExpr(0), Call, C.getState(),
                                     /*Hold=*/true, IsKnownToBeAllocatedMemory,
                                     AllocationFamily(AF_Malloc),
                                     /*ReturnsNullOnFailure=*/true);

  C.addTransition(State);
}

ProgramStateRef
MallocChecker::MallocMemReturnsAttr(CheckerContext &C, const CallEvent &Call,
                                    const OwnershipAttr *Att,
                                    ProgramStateRef State) const {
  if (!State)
    return nullptr;

  auto attrClassName = Att->getModule()->getName();
  auto Family = AllocationFamily(AF_Custom, attrClassName);

  if (!Att->args().empty()) {
    return MallocMemAux(C, Call,
                        Call.getArgExpr(Att->args_begin()->getASTIndex()),
                        UnknownVal(), State, Family);
  }
  return MallocMemAux(C, Call, UnknownVal(), UnknownVal(), State, Family);
}

ProgramStateRef MallocChecker::MallocBindRetVal(CheckerContext &C,
                                                const CallEvent &Call,
                                                ProgramStateRef State,
                                                bool isAlloca) const {
  const Expr *CE = Call.getOriginExpr();

  // We expect the allocation functions to return a pointer.
  if (!Loc::isLocType(CE->getType()))
    return nullptr;

  unsigned Count = C.blockCount();
  SValBuilder &SVB = C.getSValBuilder();
  const LocationContext *LCtx = C.getPredecessor()->getLocationContext();
  DefinedSVal RetVal =
      isAlloca ? SVB.getAllocaRegionVal(CE, LCtx, Count)
               : SVB.getConjuredHeapSymbolVal(Call.getCFGElementRef(), LCtx,
                                              CE->getType(), Count);
  return State->BindExpr(CE, C.getLocationContext(), RetVal);
}

ProgramStateRef MallocChecker::MallocMemAux(CheckerContext &C,
                                            const CallEvent &Call,
                                            const Expr *SizeEx, SVal Init,
                                            ProgramStateRef State,
                                            AllocationFamily Family) const {
  if (!State)
    return nullptr;

  assert(SizeEx);
  return MallocMemAux(C, Call, C.getSVal(SizeEx), Init, State, Family);
}

void MallocChecker::reportTaintBug(StringRef Msg, ProgramStateRef State,
                                   CheckerContext &C,
                                   llvm::ArrayRef<SymbolRef> TaintedSyms,
                                   AllocationFamily Family) const {
  if (ExplodedNode *N = C.generateNonFatalErrorNode(State, this)) {
    auto R =
        std::make_unique<PathSensitiveBugReport>(TaintedAllocChecker, Msg, N);
    for (const auto *TaintedSym : TaintedSyms) {
      R->markInteresting(TaintedSym);
    }
    C.emitReport(std::move(R));
  }
}

void MallocChecker::checkTaintedness(CheckerContext &C, const CallEvent &Call,
                                     const SVal SizeSVal, ProgramStateRef State,
                                     AllocationFamily Family) const {
  if (!TaintedAllocChecker.isEnabled())
    return;
  std::vector<SymbolRef> TaintedSyms =
      taint::getTaintedSymbols(State, SizeSVal);
  if (TaintedSyms.empty())
    return;

  SValBuilder &SVB = C.getSValBuilder();
  QualType SizeTy = SVB.getContext().getSizeType();
  QualType CmpTy = SVB.getConditionType();
  // In case the symbol is tainted, we give a warning if the
  // size is larger than SIZE_MAX/4
  BasicValueFactory &BVF = SVB.getBasicValueFactory();
  const llvm::APSInt MaxValInt = BVF.getMaxValue(SizeTy);
  NonLoc MaxLength =
      SVB.makeIntVal(MaxValInt / APSIntType(MaxValInt).getValue(4));
  std::optional<NonLoc> SizeNL = SizeSVal.getAs<NonLoc>();
  auto Cmp = SVB.evalBinOpNN(State, BO_GE, *SizeNL, MaxLength, CmpTy)
                 .getAs<DefinedOrUnknownSVal>();
  if (!Cmp)
    return;
  auto [StateTooLarge, StateNotTooLarge] = State->assume(*Cmp);
  if (!StateTooLarge && StateNotTooLarge) {
    // We can prove that size is not too large so there is no issue.
    return;
  }

  std::string Callee = "Memory allocation function";
  if (Call.getCalleeIdentifier())
    Callee = Call.getCalleeIdentifier()->getName().str();
  reportTaintBug(
      Callee + " is called with a tainted (potentially attacker controlled) "
               "value. Make sure the value is bound checked.",
      State, C, TaintedSyms, Family);
}

ProgramStateRef MallocChecker::MallocMemAux(CheckerContext &C,
                                            const CallEvent &Call, SVal Size,
                                            SVal Init, ProgramStateRef State,
                                            AllocationFamily Family) const {
  if (!State)
    return nullptr;

  const Expr *CE = Call.getOriginExpr();

  // We expect the malloc functions to return a pointer.
  // Should have been already checked.
  assert(Loc::isLocType(CE->getType()) &&
         "Allocation functions must return a pointer");

  const LocationContext *LCtx = C.getPredecessor()->getLocationContext();
  SVal RetVal = State->getSVal(CE, C.getLocationContext());

  // Fill the region with the initialization value.
  State = State->bindDefaultInitial(RetVal, Init, LCtx);

  // If Size is somehow undefined at this point, this line prevents a crash.
  if (Size.isUndef())
    Size = UnknownVal();

  checkTaintedness(C, Call, Size, State, AllocationFamily(AF_Malloc));

  // Set the region's extent.
  State = setDynamicExtent(State, RetVal.getAsRegion(),
                           Size.castAs<DefinedOrUnknownSVal>());

  return MallocUpdateRefState(C, CE, State, Family);
}

static ProgramStateRef MallocUpdateRefState(CheckerContext &C, const Expr *E,
                                            ProgramStateRef State,
                                            AllocationFamily Family,
                                            std::optional<SVal> RetVal) {
  if (!State)
    return nullptr;

  // Get the return value.
  if (!RetVal)
    RetVal = State->getSVal(E, C.getLocationContext());

  // We expect the malloc functions to return a pointer.
  if (!RetVal->getAs<Loc>())
    return nullptr;

  SymbolRef Sym = RetVal->getAsLocSymbol();

  // NOTE: If this was an `alloca()` call, then `RetVal` holds an
  // `AllocaRegion`, so `Sym` will be a nullpointer because `AllocaRegion`s do
  // not have an associated symbol. However, this distinct region type means
  // that we don't need to store anything about them in `RegionState`.

  if (Sym)
    return State->set<RegionState>(Sym, RefState::getAllocated(Family, E));

  return State;
}

ProgramStateRef MallocChecker::FreeMemAttr(CheckerContext &C,
                                           const CallEvent &Call,
                                           const OwnershipAttr *Att,
                                           ProgramStateRef State) const {
  if (!State)
    return nullptr;

  auto attrClassName = Att->getModule()->getName();
  auto Family = AllocationFamily(AF_Custom, attrClassName);

  bool IsKnownToBeAllocated = false;

  for (const auto &Arg : Att->args()) {
    ProgramStateRef StateI =
        FreeMemAux(C, Call, State, Arg.getASTIndex(),
                   Att->getOwnKind() == OwnershipAttr::Holds,
                   IsKnownToBeAllocated, Family);
    if (StateI)
      State = StateI;
  }
  return State;
}

ProgramStateRef MallocChecker::FreeMemAux(CheckerContext &C,
                                          const CallEvent &Call,
                                          ProgramStateRef State, unsigned Num,
                                          bool Hold, bool &IsKnownToBeAllocated,
                                          AllocationFamily Family,
                                          bool ReturnsNullOnFailure) const {
  if (!State)
    return nullptr;

  if (Call.getNumArgs() < (Num + 1))
    return nullptr;

  return FreeMemAux(C, Call.getArgExpr(Num), Call, State, Hold,
                    IsKnownToBeAllocated, Family, ReturnsNullOnFailure);
}

/// Checks if the previous call to free on the given symbol failed - if free
/// failed, returns true. Also, returns the corresponding return value symbol.
static bool didPreviousFreeFail(ProgramStateRef State,
                                SymbolRef Sym, SymbolRef &RetStatusSymbol) {
  const SymbolRef *Ret = State->get<FreeReturnValue>(Sym);
  if (Ret) {
    assert(*Ret && "We should not store the null return symbol");
    ConstraintManager &CMgr = State->getConstraintManager();
    ConditionTruthVal FreeFailed = CMgr.isNull(State, *Ret);
    RetStatusSymbol = *Ret;
    return FreeFailed.isConstrainedTrue();
  }
  return false;
}

static void printOwnershipTakesList(raw_ostream &os, CheckerContext &C,
                                    const Expr *E) {
  const CallExpr *CE = dyn_cast<CallExpr>(E);

  if (!CE)
    return;

  const FunctionDecl *FD = CE->getDirectCallee();
  if (!FD)
    return;

  // Only one ownership_takes attribute is allowed.
  for (const auto *I : FD->specific_attrs<OwnershipAttr>()) {
    if (I->getOwnKind() != OwnershipAttr::Takes)
      continue;

    os << ", which takes ownership of '" << I->getModule()->getName() << '\'';
    break;
  }
}

static bool printMemFnName(raw_ostream &os, CheckerContext &C, const Expr *E) {
  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
    // FIXME: This doesn't handle indirect calls.
    const FunctionDecl *FD = CE->getDirectCallee();
    if (!FD)
      return false;

    os << '\'' << *FD;

    if (!FD->isOverloadedOperator())
      os << "()";

    os << '\'';
    return true;
  }

  if (const ObjCMessageExpr *Msg = dyn_cast<ObjCMessageExpr>(E)) {
    if (Msg->isInstanceMessage())
      os << "-";
    else
      os << "+";
    Msg->getSelector().print(os);
    return true;
  }

  if (const CXXNewExpr *NE = dyn_cast<CXXNewExpr>(E)) {
    os << "'"
       << getOperatorSpelling(NE->getOperatorNew()->getOverloadedOperator())
       << "'";
    return true;
  }

  if (const CXXDeleteExpr *DE = dyn_cast<CXXDeleteExpr>(E)) {
    os << "'"
       << getOperatorSpelling(DE->getOperatorDelete()->getOverloadedOperator())
       << "'";
    return true;
  }

  return false;
}

static void printExpectedAllocName(raw_ostream &os, AllocationFamily Family) {

  switch (Family.Kind) {
  case AF_Malloc:
    os << "'malloc()'";
    return;
  case AF_CXXNew:
    os << "'new'";
    return;
  case AF_CXXNewArray:
    os << "'new[]'";
    return;
  case AF_IfNameIndex:
    os << "'if_nameindex()'";
    return;
  case AF_InnerBuffer:
    os << "container-specific allocator";
    return;
  case AF_Custom:
    os << Family.CustomName.value();
    return;
  case AF_Alloca:
  case AF_None:
    assert(false && "not a deallocation expression");
  }
}

static void printExpectedDeallocName(raw_ostream &os, AllocationFamily Family) {
  switch (Family.Kind) {
  case AF_Malloc:
    os << "'free()'";
    return;
  case AF_CXXNew:
    os << "'delete'";
    return;
  case AF_CXXNewArray:
    os << "'delete[]'";
    return;
  case AF_IfNameIndex:
    os << "'if_freenameindex()'";
    return;
  case AF_InnerBuffer:
    os << "container-specific deallocator";
    return;
  case AF_Custom:
    os << "function that takes ownership of '" << Family.CustomName.value()
       << "\'";
    return;
  case AF_Alloca:
  case AF_None:
    assert(false && "not a deallocation expression");
  }
}

ProgramStateRef
MallocChecker::FreeMemAux(CheckerContext &C, const Expr *ArgExpr,
                          const CallEvent &Call, ProgramStateRef State,
                          bool Hold, bool &IsKnownToBeAllocated,
                          AllocationFamily Family, bool ReturnsNullOnFailure,
                          std::optional<SVal> ArgValOpt) const {

  if (!State)
    return nullptr;

  SVal ArgVal = ArgValOpt.value_or(C.getSVal(ArgExpr));
  if (!isa<DefinedOrUnknownSVal>(ArgVal))
    return nullptr;
  DefinedOrUnknownSVal location = ArgVal.castAs<DefinedOrUnknownSVal>();

  // Check for null dereferences.
  if (!isa<Loc>(location))
    return nullptr;

  // The explicit NULL case, no operation is performed.
  ProgramStateRef notNullState, nullState;
  std::tie(notNullState, nullState) = State->assume(location);
  if (nullState && !notNullState)
    return nullptr;

  // Unknown values could easily be okay
  // Undefined values are handled elsewhere
  if (ArgVal.isUnknownOrUndef())
    return nullptr;

  const MemRegion *R = ArgVal.getAsRegion();
  const Expr *ParentExpr = Call.getOriginExpr();

  // NOTE: We detected a bug, but the checker under whose name we would emit the
  // error could be disabled. Generally speaking, the MallocChecker family is an
  // integral part of the Static Analyzer, and disabling any part of it should
  // only be done under exceptional circumstances, such as frequent false
  // positives. If this is the case, we can reasonably believe that there are
  // serious faults in our understanding of the source code, and even if we
  // don't emit an warning, we should terminate further analysis with a sink
  // node.

  // Nonlocs can't be freed, of course.
  // Non-region locations (labels and fixed addresses) also shouldn't be freed.
  if (!R) {
    // Exception:
    // If the macro ZERO_SIZE_PTR is defined, this could be a kernel source
    // code. In that case, the ZERO_SIZE_PTR defines a special value used for a
    // zero-sized memory block which is allowed to be freed, despite not being a
    // null pointer.
    if (Family.Kind != AF_Malloc || !isArgZERO_SIZE_PTR(State, C, ArgVal))
      HandleNonHeapDealloc(C, ArgVal, ArgExpr->getSourceRange(), ParentExpr,
                           Family);
    return nullptr;
  }

  R = R->StripCasts();

  // Blocks might show up as heap data, but should not be free()d
  if (isa<BlockDataRegion>(R)) {
    HandleNonHeapDealloc(C, ArgVal, ArgExpr->getSourceRange(), ParentExpr,
                         Family);
    return nullptr;
  }

  // Parameters, locals, statics, globals, and memory returned by
  // __builtin_alloca() shouldn't be freed.
  if (!R->hasMemorySpace<UnknownSpaceRegion, HeapSpaceRegion>(State)) {
    // Regions returned by malloc() are represented by SymbolicRegion objects
    // within HeapSpaceRegion. Of course, free() can work on memory allocated
    // outside the current function, so UnknownSpaceRegion is also a
    // possibility here.

    if (isa<AllocaRegion>(R))
      HandleFreeAlloca(C, ArgVal, ArgExpr->getSourceRange());
    else
      HandleNonHeapDealloc(C, ArgVal, ArgExpr->getSourceRange(), ParentExpr,
                           Family);

    return nullptr;
  }

  const SymbolicRegion *SrBase = dyn_cast<SymbolicRegion>(R->getBaseRegion());
  // Various cases could lead to non-symbol values here.
  // For now, ignore them.
  if (!SrBase)
    return nullptr;

  SymbolRef SymBase = SrBase->getSymbol();
  const RefState *RsBase = State->get<RegionState>(SymBase);
  SymbolRef PreviousRetStatusSymbol = nullptr;

  IsKnownToBeAllocated =
      RsBase && (RsBase->isAllocated() || RsBase->isAllocatedOfSizeZero());

  if (RsBase) {

    // Memory returned by alloca() shouldn't be freed.
    if (RsBase->getAllocationFamily().Kind == AF_Alloca) {
      HandleFreeAlloca(C, ArgVal, ArgExpr->getSourceRange());
      return nullptr;
    }

    // Check for double free first.
    if ((RsBase->isReleased() || RsBase->isRelinquished()) &&
        !didPreviousFreeFail(State, SymBase, PreviousRetStatusSymbol)) {
      HandleDoubleFree(C, ParentExpr->getSourceRange(), RsBase->isReleased(),
                       SymBase, PreviousRetStatusSymbol);
      return nullptr;
    }

    // If the pointer is allocated or escaped, but we are now trying to free it,
    // check that the call to free is proper.
    if (RsBase->isAllocated() || RsBase->isAllocatedOfSizeZero() ||
        RsBase->isEscaped()) {

      // Check if an expected deallocation function matches the real one.
      bool DeallocMatchesAlloc = RsBase->getAllocationFamily() == Family;
      if (!DeallocMatchesAlloc) {
        HandleMismatchedDealloc(C, ArgExpr->getSourceRange(), ParentExpr,
                                RsBase, SymBase, Hold);
        return nullptr;
      }

      // Check if the memory location being freed is the actual location
      // allocated, or an offset.
      RegionOffset Offset = R->getAsOffset();
      if (Offset.isValid() &&
          !Offset.hasSymbolicOffset() &&
          Offset.getOffset() != 0) {
        const Expr *AllocExpr = cast<Expr>(RsBase->getStmt());
        HandleOffsetFree(C, ArgVal, ArgExpr->getSourceRange(), ParentExpr,
                         Family, AllocExpr);
        return nullptr;
      }
    }
  }

  if (SymBase->getType()->isFunctionPointerType()) {
    HandleFunctionPtrFree(C, ArgVal, ArgExpr->getSourceRange(), ParentExpr,
                          Family);
    return nullptr;
  }

  // Clean out the info on previous call to free return info.
  State = State->remove<FreeReturnValue>(SymBase);

  // Keep track of the return value. If it is NULL, we will know that free
  // failed.
  if (ReturnsNullOnFailure) {
    SVal RetVal = C.getSVal(ParentExpr);
    SymbolRef RetStatusSymbol = RetVal.getAsSymbol();
    if (RetStatusSymbol) {
      C.getSymbolManager().addSymbolDependency(SymBase, RetStatusSymbol);
      State = State->set<FreeReturnValue>(SymBase, RetStatusSymbol);
    }
  }

  // If we don't know anything about this symbol, a free on it may be totally
  // valid. If this is the case, lets assume that the allocation family of the
  // freeing function is the same as the symbols allocation family, and go with
  // that.
  assert(!RsBase || (RsBase && RsBase->getAllocationFamily() == Family));

  // Assume that after memory is freed, it contains unknown values. This
  // conforts languages standards, since reading from freed memory is considered
  // UB and may result in arbitrary value.
  State = State->invalidateRegions({location}, Call.getCFGElementRef(),
                                   C.blockCount(), C.getLocationContext(),
                                   /*CausesPointerEscape=*/false,
                                   /*InvalidatedSymbols=*/nullptr);

  // Normal free.
  if (Hold)
    return State->set<RegionState>(SymBase,
                                   RefState::getRelinquished(Family,
                                                             ParentExpr));

  return State->set<RegionState>(SymBase,
                                 RefState::getReleased(Family, ParentExpr));
}

template <class T>
const T *MallocChecker::getRelevantFrontendAs(AllocationFamily Family) const {
  switch (Family.Kind) {
  case AF_Malloc:
  case AF_Alloca:
  case AF_Custom:
  case AF_IfNameIndex:
    return MallocChecker.getAs<T>();
  case AF_CXXNew:
  case AF_CXXNewArray: {
    const T *ND = NewDeleteChecker.getAs<T>();
    const T *NDL = NewDeleteLeaksChecker.getAs<T>();
    // Bugs corresponding to C++ new/delete allocations are split between these
    // two frontends.
    if constexpr (std::is_same_v<T, CheckerFrontend>) {
      assert(ND && NDL && "Casting to CheckerFrontend always succeeds");
      // Prefer NewDelete unless it's disabled and NewDeleteLeaks is enabled.
      return (!ND->isEnabled() && NDL->isEnabled()) ? NDL : ND;
    }
    assert(!(ND && NDL) &&
           "NewDelete and NewDeleteLeaks must not share a bug type");
    return ND ? ND : NDL;
  }
  case AF_InnerBuffer:
    return InnerPointerChecker.getAs<T>();
  case AF_None:
    assert(false && "no family");
    return nullptr;
  }
  assert(false && "unhandled family");
  return nullptr;
}
template <class T>
const T *MallocChecker::getRelevantFrontendAs(CheckerContext &C,
                                              SymbolRef Sym) const {
  if (C.getState()->contains<ReallocSizeZeroSymbols>(Sym))
    return MallocChecker.getAs<T>();

  const RefState *RS = C.getState()->get<RegionState>(Sym);
  assert(RS);
  return getRelevantFrontendAs<T>(RS->getAllocationFamily());
}

bool MallocChecker::SummarizeValue(raw_ostream &os, SVal V) {
  if (std::optional<nonloc::ConcreteInt> IntVal =
          V.getAs<nonloc::ConcreteInt>())
    os << "an integer (" << IntVal->getValue() << ")";
  else if (std::optional<loc::ConcreteInt> ConstAddr =
               V.getAs<loc::ConcreteInt>())
    os << "a constant address (" << ConstAddr->getValue() << ")";
  else if (std::optional<loc::GotoLabel> Label = V.getAs<loc::GotoLabel>())
    os << "the address of the label '" << Label->getLabel()->getName() << "'";
  else
    return false;

  return true;
}

bool MallocChecker::SummarizeRegion(ProgramStateRef State, raw_ostream &os,
                                    const MemRegion *MR) {
  switch (MR->getKind()) {
  case MemRegion::FunctionCodeRegionKind: {
    const NamedDecl *FD = cast<FunctionCodeRegion>(MR)->getDecl();
    if (FD)
      os << "the address of the function '" << *FD << '\'';
    else
      os << "the address of a function";
    return true;
  }
  case MemRegion::BlockCodeRegionKind:
    os << "block text";
    return true;
  case MemRegion::BlockDataRegionKind:
    // FIXME: where the block came from?
    os << "a block";
    return true;
  default: {
    const MemSpaceRegion *MS = MR->getMemorySpace(State);

    if (isa<StackLocalsSpaceRegion>(MS)) {
      const VarRegion *VR = dyn_cast<VarRegion>(MR);
      const VarDecl *VD;
      if (VR)
        VD = VR->getDecl();
      else
        VD = nullptr;

      if (VD)
        os << "the address of the local variable '" << VD->getName() << "'";
      else
        os << "the address of a local stack variable";
      return true;
    }

    if (isa<StackArgumentsSpaceRegion>(MS)) {
      const VarRegion *VR = dyn_cast<VarRegion>(MR);
      const VarDecl *VD;
      if (VR)
        VD = VR->getDecl();
      else
        VD = nullptr;

      if (VD)
        os << "the address of the parameter '" << VD->getName() << "'";
      else
        os << "the address of a parameter";
      return true;
    }

    if (isa<GlobalsSpaceRegion>(MS)) {
      const VarRegion *VR = dyn_cast<VarRegion>(MR);
      const VarDecl *VD;
      if (VR)
        VD = VR->getDecl();
      else
        VD = nullptr;

      if (VD) {
        if (VD->isStaticLocal())
          os << "the address of the static variable '" << VD->getName() << "'";
        else
          os << "the address of the global variable '" << VD->getName() << "'";
      } else
        os << "the address of a global variable";
      return true;
    }

    return false;
  }
  }
}

void MallocChecker::HandleNonHeapDealloc(CheckerContext &C, SVal ArgVal,
                                         SourceRange Range,
                                         const Expr *DeallocExpr,
                                         AllocationFamily Family) const {
  const BadFree *Frontend = getRelevantFrontendAs<BadFree>(Family);
  if (!Frontend)
    return;
  if (!Frontend->isEnabled()) {
    C.addSink();
    return;
  }

  if (ExplodedNode *N = C.generateErrorNode()) {
    SmallString<100> buf;
    llvm::raw_svector_ostream os(buf);

    const MemRegion *MR = ArgVal.getAsRegion();
    while (const ElementRegion *ER = dyn_cast_or_null<ElementRegion>(MR))
      MR = ER->getSuperRegion();

    os << "Argument to ";
    if (!printMemFnName(os, C, DeallocExpr))
      os << "deallocator";

    os << " is ";
    bool Summarized =
        MR ? SummarizeRegion(C.getState(), os, MR) : SummarizeValue(os, ArgVal);
    if (Summarized)
      os << ", which is not memory allocated by ";
    else
      os << "not memory allocated by ";

    printExpectedAllocName(os, Family);

    auto R = std::make_unique<PathSensitiveBugReport>(Frontend->BadFreeBug,
                                                      os.str(), N);
    R->markInteresting(MR);
    R->addRange(Range);
    C.emitReport(std::move(R));
  }
}

void MallocChecker::HandleFreeAlloca(CheckerContext &C, SVal ArgVal,
                                     SourceRange Range) const {
  const FreeAlloca *Frontend;

  if (MallocChecker.isEnabled())
    Frontend = &MallocChecker;
  else if (MismatchedDeallocatorChecker.isEnabled())
    Frontend = &MismatchedDeallocatorChecker;
  else {
    C.addSink();
    return;
  }

  if (ExplodedNode *N = C.generateErrorNode()) {
    auto R = std::make_unique<PathSensitiveBugReport>(
        Frontend->FreeAllocaBug,
        "Memory allocated by 'alloca()' should not be deallocated", N);
    R->markInteresting(ArgVal.getAsRegion());
    R->addRange(Range);
    C.emitReport(std::move(R));
  }
}

void MallocChecker::HandleMismatchedDealloc(CheckerContext &C,
                                            SourceRange Range,
                                            const Expr *DeallocExpr,
                                            const RefState *RS, SymbolRef Sym,
                                            bool OwnershipTransferred) const {
  if (!MismatchedDeallocatorChecker.isEnabled()) {
    C.addSink();
    return;
  }

  if (ExplodedNode *N = C.generateErrorNode()) {
    SmallString<100> buf;
    llvm::raw_svector_ostream os(buf);

    const Expr *AllocExpr = cast<Expr>(RS->getStmt());
    SmallString<20> AllocBuf;
    llvm::raw_svector_ostream AllocOs(AllocBuf);
    SmallString<20> DeallocBuf;
    llvm::raw_svector_ostream DeallocOs(DeallocBuf);

    if (OwnershipTransferred) {
      if (printMemFnName(DeallocOs, C, DeallocExpr))
        os << DeallocOs.str() << " cannot";
      else
        os << "Cannot";

      os << " take ownership of memory";

      if (printMemFnName(AllocOs, C, AllocExpr))
        os << " allocated by " << AllocOs.str();
    } else {
      os << "Memory";
      if (printMemFnName(AllocOs, C, AllocExpr))
        os << " allocated by " << AllocOs.str();

      os << " should be deallocated by ";
        printExpectedDeallocName(os, RS->getAllocationFamily());

        if (printMemFnName(DeallocOs, C, DeallocExpr))
          os << ", not " << DeallocOs.str();

        printOwnershipTakesList(os, C, DeallocExpr);
    }

    auto R = std::make_unique<PathSensitiveBugReport>(
        MismatchedDeallocatorChecker.MismatchedDeallocBug, os.str(), N);
    R->markInteresting(Sym);
    R->addRange(Range);
    R->addVisitor<MallocBugVisitor>(Sym);
    C.emitReport(std::move(R));
  }
}

void MallocChecker::HandleOffsetFree(CheckerContext &C, SVal ArgVal,
                                     SourceRange Range, const Expr *DeallocExpr,
                                     AllocationFamily Family,
                                     const Expr *AllocExpr) const {
  const OffsetFree *Frontend = getRelevantFrontendAs<OffsetFree>(Family);
  if (!Frontend)
    return;
  if (!Frontend->isEnabled()) {
    C.addSink();
    return;
  }

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

  SmallString<100> buf;
  llvm::raw_svector_ostream os(buf);
  SmallString<20> AllocNameBuf;
  llvm::raw_svector_ostream AllocNameOs(AllocNameBuf);

  const MemRegion *MR = ArgVal.getAsRegion();
  assert(MR && "Only MemRegion based symbols can have offset free errors");

  RegionOffset Offset = MR->getAsOffset();
  assert((Offset.isValid() &&
          !Offset.hasSymbolicOffset() &&
          Offset.getOffset() != 0) &&
         "Only symbols with a valid offset can have offset free errors");

  int offsetBytes = Offset.getOffset() / C.getASTContext().getCharWidth();

  os << "Argument to ";
  if (!printMemFnName(os, C, DeallocExpr))
    os << "deallocator";
  os << " is offset by "
     << offsetBytes
     << " "
     << ((abs(offsetBytes) > 1) ? "bytes" : "byte")
     << " from the start of ";
  if (AllocExpr && printMemFnName(AllocNameOs, C, AllocExpr))
    os << "memory allocated by " << AllocNameOs.str();
  else
    os << "allocated memory";

  auto R = std::make_unique<PathSensitiveBugReport>(Frontend->OffsetFreeBug,
                                                    os.str(), N);
  R->markInteresting(MR->getBaseRegion());
  R->addRange(Range);
  C.emitReport(std::move(R));
}

void MallocChecker::HandleUseAfterFree(CheckerContext &C, SourceRange Range,
                                       SymbolRef Sym) const {
  const UseFree *Frontend = getRelevantFrontendAs<UseFree>(C, Sym);
  if (!Frontend)
    return;
  if (!Frontend->isEnabled()) {
    C.addSink();
    return;
  }

  if (ExplodedNode *N = C.generateErrorNode()) {
    AllocationFamily AF =
        C.getState()->get<RegionState>(Sym)->getAllocationFamily();

    auto R = std::make_unique<PathSensitiveBugReport>(
        Frontend->UseFreeBug,
        AF.Kind == AF_InnerBuffer
            ? "Inner pointer of container used after re/deallocation"
            : "Use of memory after it is released",
        N);

    R->markInteresting(Sym);
    R->addRange(Range);
    R->addVisitor<MallocBugVisitor>(Sym);

    if (AF.Kind == AF_InnerBuffer)
      R->addVisitor(allocation_state::getInnerPointerBRVisitor(Sym));

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

void MallocChecker::HandleDoubleFree(CheckerContext &C, SourceRange Range,
                                     bool Released, SymbolRef Sym,
                                     SymbolRef PrevSym) const {
  const DoubleFree *Frontend = getRelevantFrontendAs<DoubleFree>(C, Sym);
  if (!Frontend)
    return;
  if (!Frontend->isEnabled()) {
    C.addSink();
    return;
  }

  if (ExplodedNode *N = C.generateErrorNode()) {
    auto R = std::make_unique<PathSensitiveBugReport>(
        Frontend->DoubleFreeBug,
        (Released ? "Attempt to release already released memory"
                  : "Attempt to release non-owned memory"),
        N);
    if (Range.isValid())
      R->addRange(Range);
    R->markInteresting(Sym);
    if (PrevSym)
      R->markInteresting(PrevSym);
    R->addVisitor<MallocBugVisitor>(Sym);
    C.emitReport(std::move(R));
  }
}

void MallocChecker::HandleUseZeroAlloc(CheckerContext &C, SourceRange Range,
                                       SymbolRef Sym) const {
  const UseZeroAllocated *Frontend =
      getRelevantFrontendAs<UseZeroAllocated>(C, Sym);
  if (!Frontend)
    return;
  if (!Frontend->isEnabled()) {
    C.addSink();
    return;
  }

  if (ExplodedNode *N = C.generateErrorNode()) {
    auto R = std::make_unique<PathSensitiveBugReport>(
        Frontend->UseZeroAllocatedBug, "Use of memory allocated with size zero",
        N);

    R->addRange(Range);
    if (Sym) {
      R->markInteresting(Sym);
      R->addVisitor<MallocBugVisitor>(Sym);
    }
    C.emitReport(std::move(R));
  }
}

void MallocChecker::HandleFunctionPtrFree(CheckerContext &C, SVal ArgVal,
                                          SourceRange Range,
                                          const Expr *FreeExpr,
                                          AllocationFamily Family) const {
  const BadFree *Frontend = getRelevantFrontendAs<BadFree>(Family);
  if (!Frontend)
    return;
  if (!Frontend->isEnabled()) {
    C.addSink();
    return;
  }

  if (ExplodedNode *N = C.generateErrorNode()) {
    SmallString<100> Buf;
    llvm::raw_svector_ostream Os(Buf);

    const MemRegion *MR = ArgVal.getAsRegion();
    while (const ElementRegion *ER = dyn_cast_or_null<ElementRegion>(MR))
      MR = ER->getSuperRegion();

    Os << "Argument to ";
    if (!printMemFnName(Os, C, FreeExpr))
      Os << "deallocator";

    Os << " is a function pointer";

    auto R = std::make_unique<PathSensitiveBugReport>(Frontend->BadFreeBug,
                                                      Os.str(), N);
    R->markInteresting(MR);
    R->addRange(Range);
    C.emitReport(std::move(R));
  }
}

ProgramStateRef
MallocChecker::ReallocMemAux(CheckerContext &C, const CallEvent &Call,
                             bool ShouldFreeOnFail, ProgramStateRef State,
                             AllocationFamily Family, bool SuffixWithN) const {
  if (!State)
    return nullptr;

  const CallExpr *CE = cast<CallExpr>(Call.getOriginExpr());

  if ((SuffixWithN && CE->getNumArgs() < 3) || CE->getNumArgs() < 2)
    return nullptr;

  const Expr *arg0Expr = CE->getArg(0);
  SVal Arg0Val = C.getSVal(arg0Expr);
  if (!isa<DefinedOrUnknownSVal>(Arg0Val))
    return nullptr;
  DefinedOrUnknownSVal arg0Val = Arg0Val.castAs<DefinedOrUnknownSVal>();

  SValBuilder &svalBuilder = C.getSValBuilder();

  DefinedOrUnknownSVal PtrEQ = svalBuilder.evalEQ(
      State, arg0Val, svalBuilder.makeNullWithType(arg0Expr->getType()));

  // Get the size argument.
  const Expr *Arg1 = CE->getArg(1);

  // Get the value of the size argument.
  SVal TotalSize = C.getSVal(Arg1);
  if (SuffixWithN)
    TotalSize = evalMulForBufferSize(C, Arg1, CE->getArg(2));
  if (!isa<DefinedOrUnknownSVal>(TotalSize))
    return nullptr;

  // Compare the size argument to 0.
  DefinedOrUnknownSVal SizeZero = svalBuilder.evalEQ(
      State, TotalSize.castAs<DefinedOrUnknownSVal>(),
      svalBuilder.makeIntValWithWidth(
          svalBuilder.getContext().getCanonicalSizeType(), 0));

  ProgramStateRef StatePtrIsNull, StatePtrNotNull;
  std::tie(StatePtrIsNull, StatePtrNotNull) = State->assume(PtrEQ);
  ProgramStateRef StateSizeIsZero, StateSizeNotZero;
  std::tie(StateSizeIsZero, StateSizeNotZero) = State->assume(SizeZero);
  // We only assume exceptional states if they are definitely true; if the
  // state is under-constrained, assume regular realloc behavior.
  bool PrtIsNull = StatePtrIsNull && !StatePtrNotNull;
  bool SizeIsZero = StateSizeIsZero && !StateSizeNotZero;

  // If the ptr is NULL and the size is not 0, the call is equivalent to
  // malloc(size).
  if (PrtIsNull && !SizeIsZero) {
    ProgramStateRef stateMalloc = MallocMemAux(
        C, Call, TotalSize, UndefinedVal(), StatePtrIsNull, Family);
    return stateMalloc;
  }

  // Proccess as allocation of 0 bytes.
  if (PrtIsNull && SizeIsZero)
    return State;

  assert(!PrtIsNull);

  bool IsKnownToBeAllocated = false;

  // If the size is 0, free the memory.
  if (SizeIsZero)
    // The semantics of the return value are:
    // If size was equal to 0, either NULL or a pointer suitable to be passed
    // to free() is returned. We just free the input pointer and do not add
    // any constrains on the output pointer.
    if (ProgramStateRef stateFree = FreeMemAux(
            C, Call, StateSizeIsZero, 0, false, IsKnownToBeAllocated, Family))
      return stateFree;

  // Default behavior.
  if (ProgramStateRef stateFree =
          FreeMemAux(C, Call, State, 0, false, IsKnownToBeAllocated, Family)) {

    ProgramStateRef stateRealloc =
        MallocMemAux(C, Call, TotalSize, UnknownVal(), stateFree, Family);
    if (!stateRealloc)
      return nullptr;

    OwnershipAfterReallocKind Kind = OAR_ToBeFreedAfterFailure;
    if (ShouldFreeOnFail)
      Kind = OAR_FreeOnFailure;
    else if (!IsKnownToBeAllocated)
      Kind = OAR_DoNotTrackAfterFailure;

    // Get the from and to pointer symbols as in toPtr = realloc(fromPtr, size).
    SymbolRef FromPtr = arg0Val.getLocSymbolInBase();
    SVal RetVal = stateRealloc->getSVal(CE, C.getLocationContext());
    SymbolRef ToPtr = RetVal.getAsSymbol();
    assert(FromPtr && ToPtr &&
           "By this point, FreeMemAux and MallocMemAux should have checked "
           "whether the argument or the return value is symbolic!");

    // Record the info about the reallocated symbol so that we could properly
    // process failed reallocation.
    stateRealloc = stateRealloc->set<ReallocPairs>(ToPtr,
                                                   ReallocPair(FromPtr, Kind));
    // The reallocated symbol should stay alive for as long as the new symbol.
    C.getSymbolManager().addSymbolDependency(ToPtr, FromPtr);
    return stateRealloc;
  }
  return nullptr;
}

ProgramStateRef MallocChecker::CallocMem(CheckerContext &C,
                                         const CallEvent &Call,
                                         ProgramStateRef State) const {
  if (!State)
    return nullptr;

  if (Call.getNumArgs() < 2)
    return nullptr;

  SValBuilder &svalBuilder = C.getSValBuilder();
  SVal zeroVal = svalBuilder.makeZeroVal(svalBuilder.getContext().CharTy);
  SVal TotalSize =
      evalMulForBufferSize(C, Call.getArgExpr(0), Call.getArgExpr(1));

  return MallocMemAux(C, Call, TotalSize, zeroVal, State,
                      AllocationFamily(AF_Malloc));
}

MallocChecker::LeakInfo MallocChecker::getAllocationSite(const ExplodedNode *N,
                                                         SymbolRef Sym,
                                                         CheckerContext &C) {
  const LocationContext *LeakContext = N->getLocationContext();
  // Walk the ExplodedGraph backwards and find the first node that referred to
  // the tracked symbol.
  const ExplodedNode *AllocNode = N;
  const MemRegion *ReferenceRegion = nullptr;

  while (N) {
    ProgramStateRef State = N->getState();
    if (!State->get<RegionState>(Sym))
      break;

    // Find the most recent expression bound to the symbol in the current
    // context.
    if (!ReferenceRegion) {
      if (const MemRegion *MR = C.getLocationRegionIfPostStore(N)) {
        SVal Val = State->getSVal(MR);
        if (Val.getAsLocSymbol() == Sym) {
          const VarRegion *VR = MR->getBaseRegion()->getAs<VarRegion>();
          // Do not show local variables belonging to a function other than
          // where the error is reported.
          if (!VR || (VR->getStackFrame() == LeakContext->getStackFrame()))
            ReferenceRegion = MR;
        }
      }
    }

    // Allocation node, is the last node in the current or parent context in
    // which the symbol was tracked.
    const LocationContext *NContext = N->getLocationContext();
    if (NContext == LeakContext ||
        NContext->isParentOf(LeakContext))
      AllocNode = N;
    N = N->pred_empty() ? nullptr : *(N->pred_begin());
  }

  return LeakInfo(AllocNode, ReferenceRegion);
}

void MallocChecker::HandleLeak(SymbolRef Sym, ExplodedNode *N,
                               CheckerContext &C) const {
  assert(N && "HandleLeak is only called with a non-null node");

  const RefState *RS = C.getState()->get<RegionState>(Sym);
  assert(RS && "cannot leak an untracked symbol");
  AllocationFamily Family = RS->getAllocationFamily();

  if (Family.Kind == AF_Alloca)
    return;

  const Leak *Frontend = getRelevantFrontendAs<Leak>(Family);
  // Note that for leaks we don't add a sink when the relevant frontend is
  // disabled because the leak is reported with a non-fatal error node, while
  // the sink would be the "silent" alternative of a (fatal) error node.
  if (!Frontend || !Frontend->isEnabled())
    return;

  // Most bug reports are cached at the location where they occurred.
  // With leaks, we want to unique them by the location where they were
  // allocated, and only report a single path.
  PathDiagnosticLocation LocUsedForUniqueing;
  const ExplodedNode *AllocNode = nullptr;
  const MemRegion *Region = nullptr;
  std::tie(AllocNode, Region) = getAllocationSite(N, Sym, C);

  const Stmt *AllocationStmt = AllocNode->getStmtForDiagnostics();
  if (AllocationStmt)
    LocUsedForUniqueing = PathDiagnosticLocation::createBegin(AllocationStmt,
                                              C.getSourceManager(),
                                              AllocNode->getLocationContext());

  SmallString<200> buf;
  llvm::raw_svector_ostream os(buf);
  if (Region && Region->canPrintPretty()) {
    os << "Potential leak of memory pointed to by ";
    Region->printPretty(os);
  } else {
    os << "Potential memory leak";
  }

  auto R = std::make_unique<PathSensitiveBugReport>(
      Frontend->LeakBug, os.str(), N, LocUsedForUniqueing,
      AllocNode->getLocationContext()->getDecl());
  R->markInteresting(Sym);
  R->addVisitor<MallocBugVisitor>(Sym, true);
  if (ShouldRegisterNoOwnershipChangeVisitor)
    R->addVisitor<NoMemOwnershipChangeVisitor>(Sym, this);
  C.emitReport(std::move(R));
}

void MallocChecker::checkDeadSymbols(SymbolReaper &SymReaper,
                                     CheckerContext &C) const
{
  ProgramStateRef state = C.getState();
  RegionStateTy OldRS = state->get<RegionState>();
  RegionStateTy::Factory &F = state->get_context<RegionState>();

  RegionStateTy RS = OldRS;
  SmallVector<SymbolRef, 2> Errors;
  for (auto [Sym, State] : RS) {
    if (SymReaper.isDead(Sym)) {
      if (State.isAllocated() || State.isAllocatedOfSizeZero())
        Errors.push_back(Sym);
      // Remove the dead symbol from the map.
      RS = F.remove(RS, Sym);
    }
  }

  if (RS == OldRS) {
    // We shouldn't have touched other maps yet.
    assert(state->get<ReallocPairs>() ==
           C.getState()->get<ReallocPairs>());
    assert(state->get<FreeReturnValue>() ==
           C.getState()->get<FreeReturnValue>());
    return;
  }

  // Cleanup the Realloc Pairs Map.
  ReallocPairsTy RP = state->get<ReallocPairs>();
  for (auto [Sym, ReallocPair] : RP) {
    if (SymReaper.isDead(Sym) || SymReaper.isDead(ReallocPair.ReallocatedSym)) {
      state = state->remove<ReallocPairs>(Sym);
    }
  }

  // Cleanup the FreeReturnValue Map.
  FreeReturnValueTy FR = state->get<FreeReturnValue>();
  for (auto [Sym, RetSym] : FR) {
    if (SymReaper.isDead(Sym) || SymReaper.isDead(RetSym)) {
      state = state->remove<FreeReturnValue>(Sym);
    }
  }

  // Generate leak node.
  ExplodedNode *N = C.getPredecessor();
  if (!Errors.empty()) {
    N = C.generateNonFatalErrorNode(C.getState());
    if (N) {
      for (SymbolRef Sym : Errors) {
        HandleLeak(Sym, N, C);
      }
    }
  }

  C.addTransition(state->set<RegionState>(RS), N);
}

// Allowlist of owning smart pointers we want to recognize.
// Start with unique_ptr and shared_ptr; weak_ptr is excluded intentionally
// because it does not own the pointee.
static bool isSmartPtrName(StringRef Name) {
  return Name == "unique_ptr" || Name == "shared_ptr";
}

// Check if a type is a smart owning pointer type.
static bool isSmartPtrType(QualType QT) {
  QT = QT->getCanonicalTypeUnqualified();

  if (const auto *TST = QT->getAs<TemplateSpecializationType>()) {
    const TemplateDecl *TD = TST->getTemplateName().getAsTemplateDecl();
    if (!TD)
      return false;

    const auto *ND = dyn_cast_or_null<NamedDecl>(TD->getTemplatedDecl());
    if (!ND)
      return false;

    // For broader coverage we recognize all template classes with names that
    // match the allowlist even if they are not declared in namespace 'std'.
    return isSmartPtrName(ND->getName());
  }

  return false;
}

/// Helper struct for collecting smart owning pointer field regions.
/// This allows both hasSmartPtrField and
/// collectSmartPtrFieldRegions to share the same traversal logic,
/// ensuring consistency.
struct FieldConsumer {
  const MemRegion *Reg;
  CheckerContext *C;
  llvm::SmallPtrSetImpl<const MemRegion *> *Out;

  FieldConsumer(const MemRegion *Reg, CheckerContext &C,
                llvm::SmallPtrSetImpl<const MemRegion *> &Out)
      : Reg(Reg), C(&C), Out(&Out) {}

  void consume(const FieldDecl *FD) {
    SVal L = C->getState()->getLValue(FD, loc::MemRegionVal(Reg));
    if (const MemRegion *FR = L.getAsRegion())
      Out->insert(FR);
  }

  std::optional<FieldConsumer> switchToBase(const CXXRecordDecl *BaseDecl,
                                            bool IsVirtual) {
    // Get the base class region
    SVal BaseL =
        C->getState()->getLValue(BaseDecl, Reg->getAs<SubRegion>(), IsVirtual);
    if (const MemRegion *BaseObjRegion = BaseL.getAsRegion()) {
      // Return a consumer for the base class
      return FieldConsumer{BaseObjRegion, *C, *Out};
    }
    return std::nullopt;
  }
};

/// Check if a record type has smart owning pointer fields (directly or in base
/// classes). When FC is provided, also collect the field regions.
///
/// This function has dual behavior:
/// - When FC is nullopt: Returns true if smart pointer fields are found
/// - When FC is provided: Always returns false, but collects field regions
///   as a side effect through the FieldConsumer
///
/// Note: When FC is provided, the return value should be ignored since the
/// function performs full traversal for collection and always returns false
/// to avoid early termination.
static bool hasSmartPtrField(const CXXRecordDecl *CRD,
                             std::optional<FieldConsumer> FC = std::nullopt) {
  // Check direct fields
  for (const FieldDecl *FD : CRD->fields()) {
    if (isSmartPtrType(FD->getType())) {
      if (!FC)
        return true;
      FC->consume(FD);
    }
  }

  // Check fields from base classes
  for (const CXXBaseSpecifier &BaseSpec : CRD->bases()) {
    if (const CXXRecordDecl *BaseDecl =
            BaseSpec.getType()->getAsCXXRecordDecl()) {
      std::optional<FieldConsumer> NewFC;
      if (FC) {
        NewFC = FC->switchToBase(BaseDecl, BaseSpec.isVirtual());
        if (!NewFC)
          continue;
      }
      bool Found = hasSmartPtrField(BaseDecl, NewFC);
      if (Found && !FC)
        return true;
    }
  }
  return false;
}

/// Check if an expression is an rvalue record type passed by value.
static bool isRvalueByValueRecord(const Expr *AE) {
  if (AE->isGLValue())
    return false;

  QualType T = AE->getType();
  if (!T->isRecordType() || T->isReferenceType())
    return false;

  // Accept common temp/construct forms but don't overfit.
  return isa<CXXTemporaryObjectExpr, MaterializeTemporaryExpr, CXXConstructExpr,
             InitListExpr, ImplicitCastExpr, CXXBindTemporaryExpr>(AE);
}

/// Check if an expression is an rvalue record with smart owning pointer fields
/// passed by value.
static bool isRvalueByValueRecordWithSmartPtr(const Expr *AE) {
  if (!isRvalueByValueRecord(AE))
    return false;

  const auto *CRD = AE->getType()->getAsCXXRecordDecl();
  return CRD && hasSmartPtrField(CRD);
}

/// Check if a CXXRecordDecl has a name matching recognized smart pointer names.
static bool isSmartPtrRecord(const CXXRecordDecl *RD) {
  if (!RD)
    return false;

  // Check the record name directly and accept both std and custom smart pointer
  // implementations for broader coverage
  return isSmartPtrName(RD->getName());
}

/// Check if a call is a constructor of a smart owning pointer class that
/// accepts pointer parameters.
static bool isSmartPtrCall(const CallEvent &Call) {
  // Only check for smart pointer constructor calls
  const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(Call.getDecl());
  if (!CD)
    return false;

  const auto *RD = CD->getParent();
  if (!isSmartPtrRecord(RD))
    return false;

  // Check if constructor takes a pointer parameter
  for (const auto *Param : CD->parameters()) {
    QualType ParamType = Param->getType();
    if (ParamType->isPointerType() && !ParamType->isFunctionPointerType() &&
        !ParamType->isVoidPointerType()) {
      return true;
    }
  }

  return false;
}

/// Collect memory regions of smart owning pointer fields from a record type
/// (including fields from base classes).
static void
collectSmartPtrFieldRegions(const MemRegion *Reg, QualType RecQT,
                            CheckerContext &C,
                            llvm::SmallPtrSetImpl<const MemRegion *> &Out) {
  if (!Reg)
    return;

  const auto *CRD = RecQT->getAsCXXRecordDecl();
  if (!CRD)
    return;

  FieldConsumer FC{Reg, C, Out};
  hasSmartPtrField(CRD, FC);
}

/// Handle smart pointer constructor calls by escaping allocated symbols
/// that are passed as pointer arguments to the constructor.
ProgramStateRef MallocChecker::handleSmartPointerConstructorArguments(
    const CallEvent &Call, ProgramStateRef State) const {
  const auto *CD = cast<CXXConstructorDecl>(Call.getDecl());
  for (unsigned I = 0, E = std::min(Call.getNumArgs(), CD->getNumParams());
       I != E; ++I) {
    const Expr *ArgExpr = Call.getArgExpr(I);
    if (!ArgExpr)
      continue;

    QualType ParamType = CD->getParamDecl(I)->getType();
    if (ParamType->isPointerType() && !ParamType->isFunctionPointerType() &&
        !ParamType->isVoidPointerType()) {
      // This argument is a pointer being passed to smart pointer constructor
      SVal ArgVal = Call.getArgSVal(I);
      SymbolRef Sym = ArgVal.getAsSymbol();
      if (Sym && State->contains<RegionState>(Sym)) {
        const RefState *RS = State->get<RegionState>(Sym);
        if (RS && (RS->isAllocated() || RS->isAllocatedOfSizeZero())) {
          State = State->set<RegionState>(Sym, RefState::getEscaped(RS));
        }
      }
    }
  }
  return State;
}

/// Handle all smart pointer related processing in function calls.
/// This includes both direct smart pointer constructor calls and by-value
/// arguments containing smart pointer fields.
ProgramStateRef MallocChecker::handleSmartPointerRelatedCalls(
    const CallEvent &Call, CheckerContext &C, ProgramStateRef State) const {

  // Handle direct smart pointer constructor calls first
  if (isSmartPtrCall(Call)) {
    return handleSmartPointerConstructorArguments(Call, State);
  }

  // Handle smart pointer fields in by-value record arguments
  llvm::SmallPtrSet<const MemRegion *, 8> SmartPtrFieldRoots;
  for (unsigned I = 0, E = Call.getNumArgs(); I != E; ++I) {
    const Expr *AE = Call.getArgExpr(I);
    if (!AE)
      continue;
    AE = AE->IgnoreParenImpCasts();

    if (!isRvalueByValueRecordWithSmartPtr(AE))
      continue;

    // Find a region for the argument.
    SVal ArgVal = Call.getArgSVal(I);
    const MemRegion *ArgRegion = ArgVal.getAsRegion();
    // Collect direct smart owning pointer field regions
    collectSmartPtrFieldRegions(ArgRegion, AE->getType(), C,
                                SmartPtrFieldRoots);
  }

  // Escape symbols reachable from smart pointer fields
  if (!SmartPtrFieldRoots.empty()) {
    SmallVector<const MemRegion *, 8> SmartPtrFieldRootsVec(
        SmartPtrFieldRoots.begin(), SmartPtrFieldRoots.end());
    State = EscapeTrackedCallback::EscapeTrackedRegionsReachableFrom(
        SmartPtrFieldRootsVec, State);
  }

  return State;
}

void MallocChecker::checkPostCall(const CallEvent &Call,
                                  CheckerContext &C) const {
  // Handle existing post-call handlers first
  if (const auto *PostFN = PostFnMap.lookup(Call)) {
    (*PostFN)(this, C.getState(), Call, C);
    return; // Post-handler already called addTransition, we're done
  }

  // Handle smart pointer related processing only if no post-handler was called
  C.addTransition(handleSmartPointerRelatedCalls(Call, C, C.getState()));
}

void MallocChecker::checkPreCall(const CallEvent &Call,
                                 CheckerContext &C) const {

  if (const auto *DC = dyn_cast<CXXDeallocatorCall>(&Call)) {
    const CXXDeleteExpr *DE = DC->getOriginExpr();

    // FIXME: I don't see a good reason for restricting the check against
    // use-after-free violations to the case when NewDeleteChecker is disabled.
    // (However, if NewDeleteChecker is enabled, perhaps it would be better to
    // do this check a bit later?)
    if (!NewDeleteChecker.isEnabled())
      if (SymbolRef Sym = C.getSVal(DE->getArgument()).getAsSymbol())
        checkUseAfterFree(Sym, C, DE->getArgument());

    if (!isStandardNewDelete(DC->getDecl()))
      return;

    ProgramStateRef State = C.getState();
    bool IsKnownToBeAllocated;
    State = FreeMemAux(
        C, DE->getArgument(), Call, State,
        /*Hold*/ false, IsKnownToBeAllocated,
        AllocationFamily(DE->isArrayForm() ? AF_CXXNewArray : AF_CXXNew));

    C.addTransition(State);
    return;
  }

  // If we see a `CXXDestructorCall` (that is, an _implicit_ destructor call)
  // to a region that's symbolic and known to be already freed, then it must be
  // implicitly triggered by a `delete` expression. In this situation we should
  // emit a `DoubleFree` report _now_ (before entering the call to the
  // destructor) because otherwise the destructor call can trigger a
  // use-after-free bug (by accessing any member variable) and that would be
  // (technically valid, but) less user-friendly report than the `DoubleFree`.
  if (const auto *DC = dyn_cast<CXXDestructorCall>(&Call)) {
    SymbolRef Sym = DC->getCXXThisVal().getAsSymbol();
    if (!Sym)
      return;
    if (isReleased(Sym, C)) {
      HandleDoubleFree(C, SourceRange(), /*Released=*/true, Sym,
                       /*PrevSym=*/nullptr);
      return;
    }
  }

  // We need to handle getline pre-conditions here before the pointed region
  // gets invalidated by StreamChecker
  if (const auto *PreFN = PreFnMap.lookup(Call)) {
    (*PreFN)(this, C.getState(), Call, C);
    return;
  }

  // We will check for double free in the `evalCall` callback.
  // FIXME: It would be more logical to emit double free and use-after-free
  // reports via the same pathway (because double free is essentially a specia
  // case of use-after-free).
  if (const AnyFunctionCall *FC = dyn_cast<AnyFunctionCall>(&Call)) {
    const FunctionDecl *FD = FC->getDecl();
    if (!FD)
      return;

    // FIXME: I suspect we should remove `MallocChecker.isEnabled() &&` because
    // it's fishy that the enabled/disabled state of one frontend may influence
    // reports produced by other frontends.
    if (MallocChecker.isEnabled() && isFreeingCall(Call))
      return;
  }

  // Check if the callee of a method is deleted.
  if (const CXXInstanceCall *CC = dyn_cast<CXXInstanceCall>(&Call)) {
    SymbolRef Sym = CC->getCXXThisVal().getAsSymbol();
    if (!Sym || checkUseAfterFree(Sym, C, CC->getCXXThisExpr()))
      return;
  }

  // Check arguments for being used after free.
  for (unsigned I = 0, E = Call.getNumArgs(); I != E; ++I) {
    SVal ArgSVal = Call.getArgSVal(I);
    if (isa<Loc>(ArgSVal)) {
      SymbolRef Sym = ArgSVal.getAsSymbol(/*IncludeBaseRegions=*/true);
      if (!Sym)
        continue;
      if (checkUseAfterFree(Sym, C, Call.getArgExpr(I)))
        return;
    }
  }
}

void MallocChecker::checkPreStmt(const ReturnStmt *S,
                                 CheckerContext &C) const {
  checkEscapeOnReturn(S, C);
}

// In the CFG, automatic destructors come after the return statement.
// This callback checks for returning memory that is freed by automatic
// destructors, as those cannot be reached in checkPreStmt().
void MallocChecker::checkEndFunction(const ReturnStmt *S,
                                     CheckerContext &C) const {
  checkEscapeOnReturn(S, C);
}

void MallocChecker::checkEscapeOnReturn(const ReturnStmt *S,
                                        CheckerContext &C) const {
  if (!S)
    return;

  const Expr *E = S->getRetValue();
  if (!E)
    return;

  // Check if we are returning a symbol.
  ProgramStateRef State = C.getState();
  SVal RetVal = C.getSVal(E);
  SymbolRef Sym = RetVal.getAsSymbol();
  if (!Sym)
    // If we are returning a field of the allocated struct or an array element,
    // the callee could still free the memory.
    if (const MemRegion *MR = RetVal.getAsRegion())
      if (isa<FieldRegion, ElementRegion>(MR))
        if (const SymbolicRegion *BMR =
              dyn_cast<SymbolicRegion>(MR->getBaseRegion()))
          Sym = BMR->getSymbol();

  // Check if we are returning freed memory.
  if (Sym)
    checkUseAfterFree(Sym, C, E);
}

// TODO: Blocks should be either inlined or should call invalidate regions
// upon invocation. After that's in place, special casing here will not be
// needed.
void MallocChecker::checkPostStmt(const BlockExpr *BE,
                                  CheckerContext &C) const {

  // Scan the BlockDecRefExprs for any object the retain count checker
  // may be tracking.
  if (!BE->getBlockDecl()->hasCaptures())
    return;

  ProgramStateRef state = C.getState();
  const BlockDataRegion *R =
    cast<BlockDataRegion>(C.getSVal(BE).getAsRegion());

  auto ReferencedVars = R->referenced_vars();
  if (ReferencedVars.empty())
    return;

  SmallVector<const MemRegion*, 10> Regions;
  const LocationContext *LC = C.getLocationContext();
  MemRegionManager &MemMgr = C.getSValBuilder().getRegionManager();

  for (const auto &Var : ReferencedVars) {
    const VarRegion *VR = Var.getCapturedRegion();
    if (VR->getSuperRegion() == R) {
      VR = MemMgr.getVarRegion(VR->getDecl(), LC);
    }
    Regions.push_back(VR);
  }

  state =
    state->scanReachableSymbols<StopTrackingCallback>(Regions).getState();
  C.addTransition(state);
}

static bool isReleased(SymbolRef Sym, CheckerContext &C) {
  assert(Sym);
  const RefState *RS = C.getState()->get<RegionState>(Sym);
  return (RS && RS->isReleased());
}

bool MallocChecker::suppressDeallocationsInSuspiciousContexts(
    const CallEvent &Call, CheckerContext &C) const {
  if (Call.getNumArgs() == 0)
    return false;

  StringRef FunctionStr = "";
  if (const auto *FD = dyn_cast<FunctionDecl>(C.getStackFrame()->getDecl()))
    if (const Stmt *Body = FD->getBody())
      if (Body->getBeginLoc().isValid())
        FunctionStr =
            Lexer::getSourceText(CharSourceRange::getTokenRange(
                                     {FD->getBeginLoc(), Body->getBeginLoc()}),
                                 C.getSourceManager(), C.getLangOpts());

  // We do not model the Integer Set Library's retain-count based allocation.
  if (!FunctionStr.contains("__isl_"))
    return false;

  ProgramStateRef State = C.getState();

  for (const Expr *Arg : cast<CallExpr>(Call.getOriginExpr())->arguments())
    if (SymbolRef Sym = C.getSVal(Arg).getAsSymbol())
      if (const RefState *RS = State->get<RegionState>(Sym))
        State = State->set<RegionState>(Sym, RefState::getEscaped(RS));

  C.addTransition(State);
  return true;
}

bool MallocChecker::checkUseAfterFree(SymbolRef Sym, CheckerContext &C,
                                      const Stmt *S) const {

  if (isReleased(Sym, C)) {
    HandleUseAfterFree(C, S->getSourceRange(), Sym);
    return true;
  }

  return false;
}

void MallocChecker::checkUseZeroAllocated(SymbolRef Sym, CheckerContext &C,
                                          const Stmt *S) const {
  assert(Sym);

  if (const RefState *RS = C.getState()->get<RegionState>(Sym)) {
    if (RS->isAllocatedOfSizeZero())
      HandleUseZeroAlloc(C, RS->getStmt()->getSourceRange(), Sym);
  }
  else if (C.getState()->contains<ReallocSizeZeroSymbols>(Sym)) {
    HandleUseZeroAlloc(C, S->getSourceRange(), Sym);
  }
}

// Check if the location is a freed symbolic region.
void MallocChecker::checkLocation(SVal l, bool isLoad, const Stmt *S,
                                  CheckerContext &C) const {
  SymbolRef Sym = l.getLocSymbolInBase();
  if (Sym) {
    checkUseAfterFree(Sym, C, S);
    checkUseZeroAllocated(Sym, C, S);
  }
}

// If a symbolic region is assumed to NULL (or another constant), stop tracking
// it - assuming that allocation failed on this path.
ProgramStateRef MallocChecker::evalAssume(ProgramStateRef state,
                                              SVal Cond,
                                              bool Assumption) const {
  RegionStateTy RS = state->get<RegionState>();
  for (SymbolRef Sym : llvm::make_first_range(RS)) {
    // If the symbol is assumed to be NULL, remove it from consideration.
    ConstraintManager &CMgr = state->getConstraintManager();
    ConditionTruthVal AllocFailed = CMgr.isNull(state, Sym);
    if (AllocFailed.isConstrainedTrue())
      state = state->remove<RegionState>(Sym);
  }

  // Realloc returns 0 when reallocation fails, which means that we should
  // restore the state of the pointer being reallocated.
  ReallocPairsTy RP = state->get<ReallocPairs>();
  for (auto [Sym, ReallocPair] : RP) {
    // If the symbol is assumed to be NULL, remove it from consideration.
    ConstraintManager &CMgr = state->getConstraintManager();
    ConditionTruthVal AllocFailed = CMgr.isNull(state, Sym);
    if (!AllocFailed.isConstrainedTrue())
      continue;

    SymbolRef ReallocSym = ReallocPair.ReallocatedSym;
    if (const RefState *RS = state->get<RegionState>(ReallocSym)) {
      if (RS->isReleased()) {
        switch (ReallocPair.Kind) {
        case OAR_ToBeFreedAfterFailure:
          state = state->set<RegionState>(ReallocSym,
              RefState::getAllocated(RS->getAllocationFamily(), RS->getStmt()));
          break;
        case OAR_DoNotTrackAfterFailure:
          state = state->remove<RegionState>(ReallocSym);
          break;
        default:
          assert(ReallocPair.Kind == OAR_FreeOnFailure);
        }
      }
    }
    state = state->remove<ReallocPairs>(Sym);
  }

  return state;
}

bool MallocChecker::mayFreeAnyEscapedMemoryOrIsModeledExplicitly(
                                              const CallEvent *Call,
                                              ProgramStateRef State,
                                              SymbolRef &EscapingSymbol) const {
  assert(Call);
  EscapingSymbol = nullptr;

  // For now, assume that any C++ or block call can free memory.
  // TODO: If we want to be more optimistic here, we'll need to make sure that
  // regions escape to C++ containers. They seem to do that even now, but for
  // mysterious reasons.
  if (!isa<SimpleFunctionCall, ObjCMethodCall>(Call))
    return true;

  // Check Objective-C messages by selector name.
  if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(Call)) {
    // If it's not a framework call, or if it takes a callback, assume it
    // can free memory.
    if (!Call->isInSystemHeader() || Call->argumentsMayEscape())
      return true;

    // If it's a method we know about, handle it explicitly post-call.
    // This should happen before the "freeWhenDone" check below.
    if (isKnownDeallocObjCMethodName(*Msg))
      return false;

    // If there's a "freeWhenDone" parameter, but the method isn't one we know
    // about, we can't be sure that the object will use free() to deallocate the
    // memory, so we can't model it explicitly. The best we can do is use it to
    // decide whether the pointer escapes.
    if (std::optional<bool> FreeWhenDone = getFreeWhenDoneArg(*Msg))
      return *FreeWhenDone;

    // If the first selector piece ends with "NoCopy", and there is no
    // "freeWhenDone" parameter set to zero, we know ownership is being
    // transferred. Again, though, we can't be sure that the object will use
    // free() to deallocate the memory, so we can't model it explicitly.
    StringRef FirstSlot = Msg->getSelector().getNameForSlot(0);
    if (FirstSlot.ends_with("NoCopy"))
      return true;

    // If the first selector starts with addPointer, insertPointer,
    // or replacePointer, assume we are dealing with NSPointerArray or similar.
    // This is similar to C++ containers (vector); we still might want to check
    // that the pointers get freed by following the container itself.
    if (FirstSlot.starts_with("addPointer") ||
        FirstSlot.starts_with("insertPointer") ||
        FirstSlot.starts_with("replacePointer") ||
        FirstSlot == "valueWithPointer") {
      return true;
    }

    // We should escape receiver on call to 'init'. This is especially relevant
    // to the receiver, as the corresponding symbol is usually not referenced
    // after the call.
    if (Msg->getMethodFamily() == OMF_init) {
      EscapingSymbol = Msg->getReceiverSVal().getAsSymbol();
      return true;
    }

    // Otherwise, assume that the method does not free memory.
    // Most framework methods do not free memory.
    return false;
  }

  // At this point the only thing left to handle is straight function calls.
  const FunctionDecl *FD = cast<SimpleFunctionCall>(Call)->getDecl();
  if (!FD)
    return true;

  // If it's one of the allocation functions we can reason about, we model
  // its behavior explicitly.
  if (isMemCall(*Call))
    return false;

  // If it's not a system call, assume it frees memory.
  if (!Call->isInSystemHeader())
    return true;

  // White list the system functions whose arguments escape.
  const IdentifierInfo *II = FD->getIdentifier();
  if (!II)
    return true;
  StringRef FName = II->getName();

  // White list the 'XXXNoCopy' CoreFoundation functions.
  // We specifically check these before
  if (FName.ends_with("NoCopy")) {
    // Look for the deallocator argument. We know that the memory ownership
    // is not transferred only if the deallocator argument is
    // 'kCFAllocatorNull'.
    for (unsigned i = 1; i < Call->getNumArgs(); ++i) {
      const Expr *ArgE = Call->getArgExpr(i)->IgnoreParenCasts();
      if (const DeclRefExpr *DE = dyn_cast<DeclRefExpr>(ArgE)) {
        StringRef DeallocatorName = DE->getFoundDecl()->getName();
        if (DeallocatorName == "kCFAllocatorNull")
          return false;
      }
    }
    return true;
  }

  // Associating streams with malloced buffers. The pointer can escape if
  // 'closefn' is specified (and if that function does free memory),
  // but it will not if closefn is not specified.
  // Currently, we do not inspect the 'closefn' function (PR12101).
  if (FName == "funopen")
    if (Call->getNumArgs() >= 4 && Call->getArgSVal(4).isConstant(0))
      return false;

  // Do not warn on pointers passed to 'setbuf' when used with std streams,
  // these leaks might be intentional when setting the buffer for stdio.
  // http://stackoverflow.com/questions/2671151/who-frees-setvbuf-buffer
  if (FName == "setbuf" || FName =="setbuffer" ||
      FName == "setlinebuf" || FName == "setvbuf") {
    if (Call->getNumArgs() >= 1) {
      const Expr *ArgE = Call->getArgExpr(0)->IgnoreParenCasts();
      if (const DeclRefExpr *ArgDRE = dyn_cast<DeclRefExpr>(ArgE))
        if (const VarDecl *D = dyn_cast<VarDecl>(ArgDRE->getDecl()))
          if (D->getCanonicalDecl()->getName().contains("std"))
            return true;
    }
  }

  // A bunch of other functions which either take ownership of a pointer or
  // wrap the result up in a struct or object, meaning it can be freed later.
  // (See RetainCountChecker.) Not all the parameters here are invalidated,
  // but the Malloc checker cannot differentiate between them. The right way
  // of doing this would be to implement a pointer escapes callback.
  if (FName == "CGBitmapContextCreate" ||
      FName == "CGBitmapContextCreateWithData" ||
      FName == "CVPixelBufferCreateWithBytes" ||
      FName == "CVPixelBufferCreateWithPlanarBytes" ||
      FName == "OSAtomicEnqueue") {
    return true;
  }

  if (FName == "postEvent" &&
      FD->getQualifiedNameAsString() == "QCoreApplication::postEvent") {
    return true;
  }

  if (FName == "connectImpl" &&
      FD->getQualifiedNameAsString() == "QObject::connectImpl") {
    return true;
  }

  if (FName == "singleShotImpl" &&
      FD->getQualifiedNameAsString() == "QTimer::singleShotImpl") {
    return true;
  }

  // Handle cases where we know a buffer's /address/ can escape.
  // Note that the above checks handle some special cases where we know that
  // even though the address escapes, it's still our responsibility to free the
  // buffer.
  if (Call->argumentsMayEscape())
    return true;

  // Otherwise, assume that the function does not free memory.
  // Most system calls do not free the memory.
  return false;
}

ProgramStateRef MallocChecker::checkPointerEscape(ProgramStateRef State,
                                             const InvalidatedSymbols &Escaped,
                                             const CallEvent *Call,
                                             PointerEscapeKind Kind) const {
  return checkPointerEscapeAux(State, Escaped, Call, Kind,
                               /*IsConstPointerEscape*/ false);
}

ProgramStateRef MallocChecker::checkConstPointerEscape(ProgramStateRef State,
                                              const InvalidatedSymbols &Escaped,
                                              const CallEvent *Call,
                                              PointerEscapeKind Kind) const {
  // If a const pointer escapes, it may not be freed(), but it could be deleted.
  return checkPointerEscapeAux(State, Escaped, Call, Kind,
                               /*IsConstPointerEscape*/ true);
}

static bool checkIfNewOrNewArrayFamily(const RefState *RS) {
  return (RS->getAllocationFamily().Kind == AF_CXXNewArray ||
          RS->getAllocationFamily().Kind == AF_CXXNew);
}

ProgramStateRef MallocChecker::checkPointerEscapeAux(
    ProgramStateRef State, const InvalidatedSymbols &Escaped,
    const CallEvent *Call, PointerEscapeKind Kind,
    bool IsConstPointerEscape) const {
  // If we know that the call does not free memory, or we want to process the
  // call later, keep tracking the top level arguments.
  SymbolRef EscapingSymbol = nullptr;
  if (Kind == PSK_DirectEscapeOnCall &&
      !mayFreeAnyEscapedMemoryOrIsModeledExplicitly(Call, State,
                                                    EscapingSymbol) &&
      !EscapingSymbol) {
    return State;
  }

  for (SymbolRef sym : Escaped) {
    if (EscapingSymbol && EscapingSymbol != sym)
      continue;

    if (const RefState *RS = State->get<RegionState>(sym))
      if (RS->isAllocated() || RS->isAllocatedOfSizeZero())
        if (!IsConstPointerEscape || checkIfNewOrNewArrayFamily(RS))
          State = State->set<RegionState>(sym, RefState::getEscaped(RS));
  }
  return State;
}

bool MallocChecker::isArgZERO_SIZE_PTR(ProgramStateRef State, CheckerContext &C,
                                       SVal ArgVal) const {
  if (!KernelZeroSizePtrValue)
    KernelZeroSizePtrValue =
        tryExpandAsInteger("ZERO_SIZE_PTR", C.getPreprocessor());

  const llvm::APSInt *ArgValKnown =
      C.getSValBuilder().getKnownValue(State, ArgVal);
  return ArgValKnown && *KernelZeroSizePtrValue &&
         ArgValKnown->getSExtValue() == **KernelZeroSizePtrValue;
}

static SymbolRef findFailedReallocSymbol(ProgramStateRef currState,
                                         ProgramStateRef prevState) {
  ReallocPairsTy currMap = currState->get<ReallocPairs>();
  ReallocPairsTy prevMap = prevState->get<ReallocPairs>();

  for (const ReallocPairsTy::value_type &Pair : prevMap) {
    SymbolRef sym = Pair.first;
    if (!currMap.lookup(sym))
      return sym;
  }

  return nullptr;
}

static bool isReferenceCountingPointerDestructor(const CXXDestructorDecl *DD) {
  if (const IdentifierInfo *II = DD->getParent()->getIdentifier()) {
    StringRef N = II->getName();
    if (N.contains_insensitive("ptr") || N.contains_insensitive("pointer")) {
      if (N.contains_insensitive("ref") || N.contains_insensitive("cnt") ||
          N.contains_insensitive("intrusive") ||
          N.contains_insensitive("shared") || N.ends_with_insensitive("rc")) {
        return true;
      }
    }
  }
  return false;
}

PathDiagnosticPieceRef MallocBugVisitor::VisitNode(const ExplodedNode *N,
                                                   BugReporterContext &BRC,
                                                   PathSensitiveBugReport &BR) {
  ProgramStateRef state = N->getState();
  ProgramStateRef statePrev = N->getFirstPred()->getState();

  const RefState *RSCurr = state->get<RegionState>(Sym);
  const RefState *RSPrev = statePrev->get<RegionState>(Sym);

  const Stmt *S = N->getStmtForDiagnostics();
  // When dealing with containers, we sometimes want to give a note
  // even if the statement is missing.
  if (!S && (!RSCurr || RSCurr->getAllocationFamily().Kind != AF_InnerBuffer))
    return nullptr;

  const LocationContext *CurrentLC = N->getLocationContext();

  // If we find an atomic fetch_add or fetch_sub within the function in which
  // the pointer was released (before the release), this is likely a release
  // point of reference-counted object (like shared pointer).
  //
  // Because we don't model atomics, and also because we don't know that the
  // original reference count is positive, we should not report use-after-frees
  // on objects deleted in such functions. This can probably be improved
  // through better shared pointer modeling.
  if (ReleaseFunctionLC && (ReleaseFunctionLC == CurrentLC ||
                            ReleaseFunctionLC->isParentOf(CurrentLC))) {
    if (const auto *AE = dyn_cast<AtomicExpr>(S)) {
      // Check for manual use of atomic builtins.
      AtomicExpr::AtomicOp Op = AE->getOp();
      if (Op == AtomicExpr::AO__c11_atomic_fetch_add ||
          Op == AtomicExpr::AO__c11_atomic_fetch_sub) {
        BR.markInvalid(getTag(), S);
        // After report is considered invalid there is no need to proceed
        // futher.
        return nullptr;
      }
    } else if (const auto *CE = dyn_cast<CallExpr>(S)) {
      // Check for `std::atomic` and such. This covers both regular method calls
      // and operator calls.
      if (const auto *MD =
              dyn_cast_or_null<CXXMethodDecl>(CE->getDirectCallee())) {
        const CXXRecordDecl *RD = MD->getParent();
        // A bit wobbly with ".contains()" because it may be like
        // "__atomic_base" or something.
        if (StringRef(RD->getNameAsString()).contains("atomic")) {
          BR.markInvalid(getTag(), S);
          // After report is considered invalid there is no need to proceed
          // futher.
          return nullptr;
        }
      }
    }
  }

  // FIXME: We will eventually need to handle non-statement-based events
  // (__attribute__((cleanup))).

  // Find out if this is an interesting point and what is the kind.
  StringRef Msg;
  std::unique_ptr<StackHintGeneratorForSymbol> StackHint = nullptr;
  SmallString<256> Buf;
  llvm::raw_svector_ostream OS(Buf);

  if (Mode == Normal) {
    if (isAllocated(RSCurr, RSPrev, S)) {
      Msg = "Memory is allocated";
      StackHint = std::make_unique<StackHintGeneratorForSymbol>(
          Sym, "Returned allocated memory");
    } else if (isReleased(RSCurr, RSPrev, S)) {
      const auto Family = RSCurr->getAllocationFamily();
      switch (Family.Kind) {
      case AF_Alloca:
      case AF_Malloc:
      case AF_Custom:
      case AF_CXXNew:
      case AF_CXXNewArray:
      case AF_IfNameIndex:
        Msg = "Memory is released";
        StackHint = std::make_unique<StackHintGeneratorForSymbol>(
            Sym, "Returning; memory was released");
        break;
      case AF_InnerBuffer: {
        const MemRegion *ObjRegion =
            allocation_state::getContainerObjRegion(statePrev, Sym);
        const auto *TypedRegion = cast<TypedValueRegion>(ObjRegion);
        QualType ObjTy = TypedRegion->getValueType();
        OS << "Inner buffer of '" << ObjTy << "' ";

        if (N->getLocation().getKind() == ProgramPoint::PostImplicitCallKind) {
          OS << "deallocated by call to destructor";
          StackHint = std::make_unique<StackHintGeneratorForSymbol>(
              Sym, "Returning; inner buffer was deallocated");
        } else {
          OS << "reallocated by call to '";
          const Stmt *S = RSCurr->getStmt();
          if (const auto *MemCallE = dyn_cast<CXXMemberCallExpr>(S)) {
            OS << MemCallE->getMethodDecl()->getDeclName();
          } else if (const auto *OpCallE = dyn_cast<CXXOperatorCallExpr>(S)) {
            OS << OpCallE->getDirectCallee()->getDeclName();
          } else if (const auto *CallE = dyn_cast<CallExpr>(S)) {
            auto &CEMgr = BRC.getStateManager().getCallEventManager();
            CallEventRef<> Call =
                CEMgr.getSimpleCall(CallE, state, CurrentLC, {nullptr, 0});
            if (const auto *D = dyn_cast_or_null<NamedDecl>(Call->getDecl()))
              OS << D->getDeclName();
            else
              OS << "unknown";
          }
          OS << "'";
          StackHint = std::make_unique<StackHintGeneratorForSymbol>(
              Sym, "Returning; inner buffer was reallocated");
        }
        Msg = OS.str();
        break;
        }
        case AF_None:
          assert(false && "Unhandled allocation family!");
          return nullptr;
        }

        // Record the stack frame that is _responsible_ for this memory release
        // event. This will be used by the false positive suppression heuristics
        // that recognize the release points of reference-counted objects.
        //
        // Usually (e.g. in C) we say that the _responsible_ stack frame is the
        // current innermost stack frame:
        ReleaseFunctionLC = CurrentLC->getStackFrame();
        // ...but if the stack contains a destructor call, then we say that the
        // outermost destructor stack frame is the _responsible_ one:
        for (const LocationContext *LC = CurrentLC; LC; LC = LC->getParent()) {
          if (const auto *DD = dyn_cast<CXXDestructorDecl>(LC->getDecl())) {
            if (isReferenceCountingPointerDestructor(DD)) {
              // This immediately looks like a reference-counting destructor.
              // We're bad at guessing the original reference count of the
              // object, so suppress the report for now.
              BR.markInvalid(getTag(), DD);

              // After report is considered invalid there is no need to proceed
              // futher.
              return nullptr;
            }

            // Switch suspection to outer destructor to catch patterns like:
            // (note that class name is distorted to bypass
            // isReferenceCountingPointerDestructor() logic)
            //
            // SmartPointr::~SmartPointr() {
            //  if (refcount.fetch_sub(1) == 1)
            //    release_resources();
            // }
            // void SmartPointr::release_resources() {
            //   free(buffer);
            // }
            //
            // This way ReleaseFunctionLC will point to outermost destructor and
            // it would be possible to catch wider range of FP.
            //
            // NOTE: it would be great to support smth like that in C, since
            // currently patterns like following won't be supressed:
            //
            // void doFree(struct Data *data) { free(data); }
            // void putData(struct Data *data)
            // {
            //   if (refPut(data))
            //     doFree(data);
            // }
            ReleaseFunctionLC = LC->getStackFrame();
          }
        }

    } else if (isRelinquished(RSCurr, RSPrev, S)) {
      Msg = "Memory ownership is transferred";
      StackHint = std::make_unique<StackHintGeneratorForSymbol>(Sym, "");
    } else if (hasReallocFailed(RSCurr, RSPrev, S)) {
      Mode = ReallocationFailed;
      Msg = "Reallocation failed";
      StackHint = std::make_unique<StackHintGeneratorForReallocationFailed>(
          Sym, "Reallocation failed");

      if (SymbolRef sym = findFailedReallocSymbol(state, statePrev)) {
        // Is it possible to fail two reallocs WITHOUT testing in between?
        assert((!FailedReallocSymbol || FailedReallocSymbol == sym) &&
          "We only support one failed realloc at a time.");
        BR.markInteresting(sym);
        FailedReallocSymbol = sym;
      }
    }

  // We are in a special mode if a reallocation failed later in the path.
  } else if (Mode == ReallocationFailed) {
    assert(FailedReallocSymbol && "No symbol to look for.");

    // Is this is the first appearance of the reallocated symbol?
    if (!statePrev->get<RegionState>(FailedReallocSymbol)) {
      // We're at the reallocation point.
      Msg = "Attempt to reallocate memory";
      StackHint = std::make_unique<StackHintGeneratorForSymbol>(
          Sym, "Returned reallocated memory");
      FailedReallocSymbol = nullptr;
      Mode = Normal;
    }
  }

  if (Msg.empty()) {
    assert(!StackHint);
    return nullptr;
  }

  assert(StackHint);

  // Generate the extra diagnostic.
  PathDiagnosticLocation Pos;
  if (!S) {
    assert(RSCurr->getAllocationFamily().Kind == AF_InnerBuffer);
    auto PostImplCall = N->getLocation().getAs<PostImplicitCall>();
    if (!PostImplCall)
      return nullptr;
    Pos = PathDiagnosticLocation(PostImplCall->getLocation(),
                                 BRC.getSourceManager());
  } else {
    Pos = PathDiagnosticLocation(S, BRC.getSourceManager(),
                                 N->getLocationContext());
  }

  auto P = std::make_shared<PathDiagnosticEventPiece>(Pos, Msg, true);
  BR.addCallStackHint(P, std::move(StackHint));
  return P;
}

void MallocChecker::printState(raw_ostream &Out, ProgramStateRef State,
                               const char *NL, const char *Sep) const {

  RegionStateTy RS = State->get<RegionState>();

  if (!RS.isEmpty()) {
    Out << Sep << "MallocChecker :" << NL;
    for (auto [Sym, Data] : RS) {
      const RefState *RefS = State->get<RegionState>(Sym);
      AllocationFamily Family = RefS->getAllocationFamily();

      const CheckerFrontend *Frontend =
          getRelevantFrontendAs<CheckerFrontend>(Family);

      Sym->dumpToStream(Out);
      Out << " : ";
      Data.dump(Out);
      if (Frontend && Frontend->isEnabled())
        Out << " (" << Frontend->getName() << ")";
      Out << NL;
    }
  }
}

namespace clang {
namespace ento {
namespace allocation_state {

ProgramStateRef
markReleased(ProgramStateRef State, SymbolRef Sym, const Expr *Origin) {
  AllocationFamily Family(AF_InnerBuffer);
  return State->set<RegionState>(Sym, RefState::getReleased(Family, Origin));
}

} // end namespace allocation_state
} // end namespace ento
} // end namespace clang

// Intended to be used in InnerPointerChecker to register the part of
// MallocChecker connected to it.
void ento::registerInnerPointerCheckerAux(CheckerManager &Mgr) {
  Mgr.getChecker<MallocChecker>()->InnerPointerChecker.enable(Mgr);
}

void ento::registerDynamicMemoryModeling(CheckerManager &Mgr) {
  auto *Chk = Mgr.getChecker<MallocChecker>();
  // FIXME: This is a "hidden" undocumented frontend but there are public
  // checker options which are attached to it.
  CheckerNameRef DMMName = Mgr.getCurrentCheckerName();
  Chk->ShouldIncludeOwnershipAnnotatedFunctions =
      Mgr.getAnalyzerOptions().getCheckerBooleanOption(DMMName, "Optimistic");
  Chk->ShouldRegisterNoOwnershipChangeVisitor =
      Mgr.getAnalyzerOptions().getCheckerBooleanOption(
          DMMName, "AddNoOwnershipChangeNotes");
}

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

#define REGISTER_CHECKER(NAME)                                                 \
  void ento::register##NAME(CheckerManager &Mgr) {                             \
    Mgr.getChecker<MallocChecker>()->NAME.enable(Mgr);                         \
  }                                                                            \
                                                                               \
  bool ento::shouldRegister##NAME(const CheckerManager &) { return true; }

// TODO: NewDelete and NewDeleteLeaks shouldn't be registered when not in C++.
REGISTER_CHECKER(MallocChecker)
REGISTER_CHECKER(NewDeleteChecker)
REGISTER_CHECKER(NewDeleteLeaksChecker)
REGISTER_CHECKER(MismatchedDeallocatorChecker)
REGISTER_CHECKER(TaintedAllocChecker)