The Tor Browser: security/sandbox/chromium/base/memory/scoped

security/sandbox/chromium/base/memory/scoped_ptr.h@ca08bd8f51b2 (annotated)

security/sandbox/chromium/base/memory/scoped_ptr.h

Wed, 31 Dec 2014 06:55:46 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:55:46 +0100
changeset 1: ca08bd8f51b2
permissions: -rw-r--r--

Added tag TORBROWSER_REPLICA for changeset 6474c204b198

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 // Scopers help you manage ownership of a pointer, helping you easily manage the
 // a pointer within a scope, and automatically destroying the pointer at the
 // end of a scope.  There are two main classes you will use, which correspond
 // to the operators new/delete and new[]/delete[].
 //
 // Example usage (scoped_ptr<T>):
 //   {
 //     scoped_ptr<Foo> foo(new Foo("wee"));
 //   }  // foo goes out of scope, releasing the pointer with it.
 //
 //   {
 //     scoped_ptr<Foo> foo;          // No pointer managed.
 //     foo.reset(new Foo("wee"));    // Now a pointer is managed.
 //     foo.reset(new Foo("wee2"));   // Foo("wee") was destroyed.
 //     foo.reset(new Foo("wee3"));   // Foo("wee2") was destroyed.
 //     foo->Method();                // Foo::Method() called.
 //     foo.get()->Method();          // Foo::Method() called.
 //     SomeFunc(foo.release());      // SomeFunc takes ownership, foo no longer
 //                                   // manages a pointer.
 //     foo.reset(new Foo("wee4"));   // foo manages a pointer again.
 //     foo.reset();                  // Foo("wee4") destroyed, foo no longer
 //                                   // manages a pointer.
 //   }  // foo wasn't managing a pointer, so nothing was destroyed.
 //
 // Example usage (scoped_ptr<T[]>):
 //   {
 //     scoped_ptr<Foo[]> foo(new Foo[100]);
 //     foo.get()->Method();  // Foo::Method on the 0th element.
 //     foo[10].Method();     // Foo::Method on the 10th element.
 //   }
 //
 // These scopers also implement part of the functionality of C++11 unique_ptr
 // in that they are "movable but not copyable."  You can use the scopers in
 // the parameter and return types of functions to signify ownership transfer
 // in to and out of a function.  When calling a function that has a scoper
 // as the argument type, it must be called with the result of an analogous
 // scoper's Pass() function or another function that generates a temporary;
 // passing by copy will NOT work.  Here is an example using scoped_ptr:
 //
 //   void TakesOwnership(scoped_ptr<Foo> arg) {
 //     // Do something with arg
 //   }
 //   scoped_ptr<Foo> CreateFoo() {
 //     // No need for calling Pass() because we are constructing a temporary
 //     // for the return value.
 //     return scoped_ptr<Foo>(new Foo("new"));
 //   }
 //   scoped_ptr<Foo> PassThru(scoped_ptr<Foo> arg) {
 //     return arg.Pass();
 //   }
 //
 //   {
 //     scoped_ptr<Foo> ptr(new Foo("yay"));  // ptr manages Foo("yay").
 //     TakesOwnership(ptr.Pass());           // ptr no longer owns Foo("yay").
 //     scoped_ptr<Foo> ptr2 = CreateFoo();   // ptr2 owns the return Foo.
 //     scoped_ptr<Foo> ptr3 =                // ptr3 now owns what was in ptr2.
 //         PassThru(ptr2.Pass());            // ptr2 is correspondingly NULL.
 //   }
 //
 // Notice that if you do not call Pass() when returning from PassThru(), or
 // when invoking TakesOwnership(), the code will not compile because scopers
 // are not copyable; they only implement move semantics which require calling
 // the Pass() function to signify a destructive transfer of state. CreateFoo()
 // is different though because we are constructing a temporary on the return
 // line and thus can avoid needing to call Pass().
 //
 // Pass() properly handles upcast in assignment, i.e. you can assign
 // scoped_ptr<Child> to scoped_ptr<Parent>:
 //
 //   scoped_ptr<Foo> foo(new Foo());
 //   scoped_ptr<FooParent> parent = foo.Pass();
 //
 // PassAs<>() should be used to upcast return value in return statement:
 //
 //   scoped_ptr<Foo> CreateFoo() {
 //     scoped_ptr<FooChild> result(new FooChild());
 //     return result.PassAs<Foo>();
 //   }
 //
 // Note that PassAs<>() is implemented only for scoped_ptr<T>, but not for
 // scoped_ptr<T[]>. This is because casting array pointers may not be safe.
 #ifndef BASE_MEMORY_SCOPED_PTR_H_
 #define BASE_MEMORY_SCOPED_PTR_H_
 // This is an implementation designed to match the anticipated future TR2
 // implementation of the scoped_ptr class and scoped_ptr_malloc (deprecated).
 #include <assert.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <algorithm>  // For std::swap().
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/move.h"
 #include "base/template_util.h"
 namespace base {
 namespace subtle {
 class RefCountedBase;
 class RefCountedThreadSafeBase;
 }  // namespace subtle
 // Function object which deletes its parameter, which must be a pointer.
 // If C is an array type, invokes 'delete[]' on the parameter; otherwise,
 // invokes 'delete'. The default deleter for scoped_ptr<T>.
 template <class T>
 struct DefaultDeleter {
   DefaultDeleter() {}
   template <typename U> DefaultDeleter(const DefaultDeleter<U>& other) {
     // IMPLEMENTATION NOTE: C++11 20.7.1.1.2p2 only provides this constructor
     // if U* is implicitly convertible to T* and U is not an array type.
     //
     // Correct implementation should use SFINAE to disable this
     // constructor. However, since there are no other 1-argument constructors,
     // using a COMPILE_ASSERT() based on is_convertible<> and requiring
     // complete types is simpler and will cause compile failures for equivalent
     // misuses.
     //
     // Note, the is_convertible<U*, T*> check also ensures that U is not an
     // array. T is guaranteed to be a non-array, so any U* where U is an array
     // cannot convert to T*.
     enum { T_must_be_complete = sizeof(T) };
     enum { U_must_be_complete = sizeof(U) };
     COMPILE_ASSERT((base::is_convertible<U*, T*>::value),
                    U_ptr_must_implicitly_convert_to_T_ptr);
   }
   inline void operator()(T* ptr) const {
     enum { type_must_be_complete = sizeof(T) };
     delete ptr;
   }
 };
 // Specialization of DefaultDeleter for array types.
 template <class T>
 struct DefaultDeleter<T[]> {
   inline void operator()(T* ptr) const {
     enum { type_must_be_complete = sizeof(T) };
     delete[] ptr;
   }
  private:
   // Disable this operator for any U != T because it is undefined to execute
   // an array delete when the static type of the array mismatches the dynamic
   // type.
   //
   // References:
   //   C++98 [expr.delete]p3
   //   http://cplusplus.github.com/LWG/lwg-defects.html#938
   template <typename U> void operator()(U* array) const;
 };
 template <class T, int n>
 struct DefaultDeleter<T[n]> {
   // Never allow someone to declare something like scoped_ptr<int[10]>.
   COMPILE_ASSERT(sizeof(T) == -1, do_not_use_array_with_size_as_type);
 };
 // Function object which invokes 'free' on its parameter, which must be
 // a pointer. Can be used to store malloc-allocated pointers in scoped_ptr:
 //
 // scoped_ptr<int, base::FreeDeleter> foo_ptr(
 //     static_cast<int*>(malloc(sizeof(int))));
 struct FreeDeleter {
   inline void operator()(void* ptr) const {
     free(ptr);
   }
 };
 namespace internal {
 template <typename T> struct IsNotRefCounted {
   enum {
     value = !base::is_convertible<T*, base::subtle::RefCountedBase*>::value &&
         !base::is_convertible<T*, base::subtle::RefCountedThreadSafeBase*>::
             value
   };
 };
 // Minimal implementation of the core logic of scoped_ptr, suitable for
 // reuse in both scoped_ptr and its specializations.
 template <class T, class D>
 class scoped_ptr_impl {
  public:
   explicit scoped_ptr_impl(T* p) : data_(p) { }
   // Initializer for deleters that have data parameters.
   scoped_ptr_impl(T* p, const D& d) : data_(p, d) {}
   // Templated constructor that destructively takes the value from another
   // scoped_ptr_impl.
   template <typename U, typename V>
   scoped_ptr_impl(scoped_ptr_impl<U, V>* other)
       : data_(other->release(), other->get_deleter()) {
     // We do not support move-only deleters.  We could modify our move
     // emulation to have base::subtle::move() and base::subtle::forward()
     // functions that are imperfect emulations of their C++11 equivalents,
     // but until there's a requirement, just assume deleters are copyable.
   }
   template <typename U, typename V>
   void TakeState(scoped_ptr_impl<U, V>* other) {
     // See comment in templated constructor above regarding lack of support
     // for move-only deleters.
     reset(other->release());
     get_deleter() = other->get_deleter();
   }
   ~scoped_ptr_impl() {
     if (data_.ptr != NULL) {
       // Not using get_deleter() saves one function call in non-optimized
       // builds.
       static_cast<D&>(data_)(data_.ptr);
     }
   }
   void reset(T* p) {
     // This is a self-reset, which is no longer allowed: http://crbug.com/162971
     if (p != NULL && p == data_.ptr)
       abort();
     // Note that running data_.ptr = p can lead to undefined behavior if
     // get_deleter()(get()) deletes this. In order to pevent this, reset()
     // should update the stored pointer before deleting its old value.
     //
     // However, changing reset() to use that behavior may cause current code to
     // break in unexpected ways. If the destruction of the owned object
     // dereferences the scoped_ptr when it is destroyed by a call to reset(),
     // then it will incorrectly dispatch calls to |p| rather than the original
     // value of |data_.ptr|.
     //
     // During the transition period, set the stored pointer to NULL while
     // deleting the object. Eventually, this safety check will be removed to
     // prevent the scenario initially described from occuring and
     // http://crbug.com/176091 can be closed.
     T* old = data_.ptr;
     data_.ptr = NULL;
     if (old != NULL)
       static_cast<D&>(data_)(old);
     data_.ptr = p;
   }
   T* get() const { return data_.ptr; }
   D& get_deleter() { return data_; }
   const D& get_deleter() const { return data_; }
   void swap(scoped_ptr_impl& p2) {
     // Standard swap idiom: 'using std::swap' ensures that std::swap is
     // present in the overload set, but we call swap unqualified so that
     // any more-specific overloads can be used, if available.
     using std::swap;
     swap(static_cast<D&>(data_), static_cast<D&>(p2.data_));
     swap(data_.ptr, p2.data_.ptr);
   }
   T* release() {
     T* old_ptr = data_.ptr;
     data_.ptr = NULL;
     return old_ptr;
   }
  private:
   // Needed to allow type-converting constructor.
   template <typename U, typename V> friend class scoped_ptr_impl;
   // Use the empty base class optimization to allow us to have a D
   // member, while avoiding any space overhead for it when D is an
   // empty class.  See e.g. http://www.cantrip.org/emptyopt.html for a good
   // discussion of this technique.
   struct Data : public D {
     explicit Data(T* ptr_in) : ptr(ptr_in) {}
     Data(T* ptr_in, const D& other) : D(other), ptr(ptr_in) {}
     T* ptr;
   };
   Data data_;
   DISALLOW_COPY_AND_ASSIGN(scoped_ptr_impl);
 };
 }  // namespace internal
 }  // namespace base
 // A scoped_ptr<T> is like a T*, except that the destructor of scoped_ptr<T>
 // automatically deletes the pointer it holds (if any).
 // That is, scoped_ptr<T> owns the T object that it points to.
 // Like a T*, a scoped_ptr<T> may hold either NULL or a pointer to a T object.
 // Also like T*, scoped_ptr<T> is thread-compatible, and once you
 // dereference it, you get the thread safety guarantees of T.
 //
 // The size of scoped_ptr is small. On most compilers, when using the
 // DefaultDeleter, sizeof(scoped_ptr<T>) == sizeof(T*). Custom deleters will
 // increase the size proportional to whatever state they need to have. See
 // comments inside scoped_ptr_impl<> for details.
 //
 // Current implementation targets having a strict subset of  C++11's
 // unique_ptr<> features. Known deficiencies include not supporting move-only
 // deleteres, function pointers as deleters, and deleters with reference
 // types.
 template <class T, class D = base::DefaultDeleter<T> >
 class scoped_ptr {
   MOVE_ONLY_TYPE_FOR_CPP_03(scoped_ptr, RValue)
   COMPILE_ASSERT(base::internal::IsNotRefCounted<T>::value,
                  T_is_refcounted_type_and_needs_scoped_refptr);
  public:
   // The element and deleter types.
   typedef T element_type;
   typedef D deleter_type;
   // Constructor.  Defaults to initializing with NULL.
   scoped_ptr() : impl_(NULL) { }
   // Constructor.  Takes ownership of p.
   explicit scoped_ptr(element_type* p) : impl_(p) { }
   // Constructor.  Allows initialization of a stateful deleter.
   scoped_ptr(element_type* p, const D& d) : impl_(p, d) { }
   // Constructor.  Allows construction from a scoped_ptr rvalue for a
   // convertible type and deleter.
   //
   // IMPLEMENTATION NOTE: C++11 unique_ptr<> keeps this constructor distinct
   // from the normal move constructor. By C++11 20.7.1.2.1.21, this constructor
   // has different post-conditions if D is a reference type. Since this
   // implementation does not support deleters with reference type,
   // we do not need a separate move constructor allowing us to avoid one
   // use of SFINAE. You only need to care about this if you modify the
   // implementation of scoped_ptr.
   template <typename U, typename V>
   scoped_ptr(scoped_ptr<U, V> other) : impl_(&other.impl_) {
     COMPILE_ASSERT(!base::is_array<U>::value, U_cannot_be_an_array);
   }
   // Constructor.  Move constructor for C++03 move emulation of this type.
   scoped_ptr(RValue rvalue) : impl_(&rvalue.object->impl_) { }
   // operator=.  Allows assignment from a scoped_ptr rvalue for a convertible
   // type and deleter.
   //
   // IMPLEMENTATION NOTE: C++11 unique_ptr<> keeps this operator= distinct from
   // the normal move assignment operator. By C++11 20.7.1.2.3.4, this templated
   // form has different requirements on for move-only Deleters. Since this
   // implementation does not support move-only Deleters, we do not need a
   // separate move assignment operator allowing us to avoid one use of SFINAE.
   // You only need to care about this if you modify the implementation of
   // scoped_ptr.
   template <typename U, typename V>
   scoped_ptr& operator=(scoped_ptr<U, V> rhs) {
     COMPILE_ASSERT(!base::is_array<U>::value, U_cannot_be_an_array);
     impl_.TakeState(&rhs.impl_);
     return *this;
   }
   // Reset.  Deletes the currently owned object, if any.
   // Then takes ownership of a new object, if given.
   void reset(element_type* p = NULL) { impl_.reset(p); }
   // Accessors to get the owned object.
   // operator* and operator-> will assert() if there is no current object.
   element_type& operator*() const {
     assert(impl_.get() != NULL);
     return *impl_.get();
   }
   element_type* operator->() const  {
     assert(impl_.get() != NULL);
     return impl_.get();
   }
   element_type* get() const { return impl_.get(); }
   // Access to the deleter.
   deleter_type& get_deleter() { return impl_.get_deleter(); }
   const deleter_type& get_deleter() const { return impl_.get_deleter(); }
   // Allow scoped_ptr<element_type> to be used in boolean expressions, but not
   // implicitly convertible to a real bool (which is dangerous).
   //
   // Note that this trick is only safe when the == and != operators
   // are declared explicitly, as otherwise "scoped_ptr1 ==
   // scoped_ptr2" will compile but do the wrong thing (i.e., convert
   // to Testable and then do the comparison).
  private:
   typedef base::internal::scoped_ptr_impl<element_type, deleter_type>
       scoped_ptr::*Testable;
  public:
   operator Testable() const { return impl_.get() ? &scoped_ptr::impl_ : NULL; }
   // Comparison operators.
   // These return whether two scoped_ptr refer to the same object, not just to
   // two different but equal objects.
   bool operator==(const element_type* p) const { return impl_.get() == p; }
   bool operator!=(const element_type* p) const { return impl_.get() != p; }
   // Swap two scoped pointers.
   void swap(scoped_ptr& p2) {
     impl_.swap(p2.impl_);
   }
   // Release a pointer.
   // The return value is the current pointer held by this object.
   // If this object holds a NULL pointer, the return value is NULL.
   // After this operation, this object will hold a NULL pointer,
   // and will not own the object any more.
   element_type* release() WARN_UNUSED_RESULT {
     return impl_.release();
   }
   // C++98 doesn't support functions templates with default parameters which
   // makes it hard to write a PassAs() that understands converting the deleter
   // while preserving simple calling semantics.
   //
   // Until there is a use case for PassAs() with custom deleters, just ignore
   // the custom deleter.
   template <typename PassAsType>
   scoped_ptr<PassAsType> PassAs() {
     return scoped_ptr<PassAsType>(Pass());
   }
  private:
   // Needed to reach into |impl_| in the constructor.
   template <typename U, typename V> friend class scoped_ptr;
   base::internal::scoped_ptr_impl<element_type, deleter_type> impl_;
   // Forbidden for API compatibility with std::unique_ptr.
   explicit scoped_ptr(int disallow_construction_from_null);
   // Forbid comparison of scoped_ptr types.  If U != T, it totally
   // doesn't make sense, and if U == T, it still doesn't make sense
   // because you should never have the same object owned by two different
   // scoped_ptrs.
   template <class U> bool operator==(scoped_ptr<U> const& p2) const;
   template <class U> bool operator!=(scoped_ptr<U> const& p2) const;
 };
 template <class T, class D>
 class scoped_ptr<T[], D> {
   MOVE_ONLY_TYPE_FOR_CPP_03(scoped_ptr, RValue)
  public:
   // The element and deleter types.
   typedef T element_type;
   typedef D deleter_type;
   // Constructor.  Defaults to initializing with NULL.
   scoped_ptr() : impl_(NULL) { }
   // Constructor. Stores the given array. Note that the argument's type
   // must exactly match T*. In particular:
   // - it cannot be a pointer to a type derived from T, because it is
   //   inherently unsafe in the general case to access an array through a
   //   pointer whose dynamic type does not match its static type (eg., if
   //   T and the derived types had different sizes access would be
   //   incorrectly calculated). Deletion is also always undefined
   //   (C++98 [expr.delete]p3). If you're doing this, fix your code.
   // - it cannot be NULL, because NULL is an integral expression, not a
   //   pointer to T. Use the no-argument version instead of explicitly
   //   passing NULL.
   // - it cannot be const-qualified differently from T per unique_ptr spec
   //   (http://cplusplus.github.com/LWG/lwg-active.html#2118). Users wanting
   //   to work around this may use implicit_cast<const T*>().
   //   However, because of the first bullet in this comment, users MUST
   //   NOT use implicit_cast<Base*>() to upcast the static type of the array.
   explicit scoped_ptr(element_type* array) : impl_(array) { }
   // Constructor.  Move constructor for C++03 move emulation of this type.
   scoped_ptr(RValue rvalue) : impl_(&rvalue.object->impl_) { }
   // operator=.  Move operator= for C++03 move emulation of this type.
   scoped_ptr& operator=(RValue rhs) {
     impl_.TakeState(&rhs.object->impl_);
     return *this;
   }
   // Reset.  Deletes the currently owned array, if any.
   // Then takes ownership of a new object, if given.
   void reset(element_type* array = NULL) { impl_.reset(array); }
   // Accessors to get the owned array.
   element_type& operator[](size_t i) const {
     assert(impl_.get() != NULL);
     return impl_.get()[i];
   }
   element_type* get() const { return impl_.get(); }
   // Access to the deleter.
   deleter_type& get_deleter() { return impl_.get_deleter(); }
   const deleter_type& get_deleter() const { return impl_.get_deleter(); }
   // Allow scoped_ptr<element_type> to be used in boolean expressions, but not
   // implicitly convertible to a real bool (which is dangerous).
  private:
   typedef base::internal::scoped_ptr_impl<element_type, deleter_type>
       scoped_ptr::*Testable;
  public:
   operator Testable() const { return impl_.get() ? &scoped_ptr::impl_ : NULL; }
   // Comparison operators.
   // These return whether two scoped_ptr refer to the same object, not just to
   // two different but equal objects.
   bool operator==(element_type* array) const { return impl_.get() == array; }
   bool operator!=(element_type* array) const { return impl_.get() != array; }
   // Swap two scoped pointers.
   void swap(scoped_ptr& p2) {
     impl_.swap(p2.impl_);
   }
   // Release a pointer.
   // The return value is the current pointer held by this object.
   // If this object holds a NULL pointer, the return value is NULL.
   // After this operation, this object will hold a NULL pointer,
   // and will not own the object any more.
   element_type* release() WARN_UNUSED_RESULT {
     return impl_.release();
   }
  private:
   // Force element_type to be a complete type.
   enum { type_must_be_complete = sizeof(element_type) };
   // Actually hold the data.
   base::internal::scoped_ptr_impl<element_type, deleter_type> impl_;
   // Disable initialization from any type other than element_type*, by
   // providing a constructor that matches such an initialization, but is
   // private and has no definition. This is disabled because it is not safe to
   // call delete[] on an array whose static type does not match its dynamic
   // type.
   template <typename U> explicit scoped_ptr(U* array);
   explicit scoped_ptr(int disallow_construction_from_null);
   // Disable reset() from any type other than element_type*, for the same
   // reasons as the constructor above.
   template <typename U> void reset(U* array);
   void reset(int disallow_reset_from_null);
   // Forbid comparison of scoped_ptr types.  If U != T, it totally
   // doesn't make sense, and if U == T, it still doesn't make sense
   // because you should never have the same object owned by two different
   // scoped_ptrs.
   template <class U> bool operator==(scoped_ptr<U> const& p2) const;
   template <class U> bool operator!=(scoped_ptr<U> const& p2) const;
 };
 // Free functions
 template <class T, class D>
 void swap(scoped_ptr<T, D>& p1, scoped_ptr<T, D>& p2) {
   p1.swap(p2);
 }
 template <class T, class D>
 bool operator==(T* p1, const scoped_ptr<T, D>& p2) {
   return p1 == p2.get();
 }
 template <class T, class D>
 bool operator!=(T* p1, const scoped_ptr<T, D>& p2) {
   return p1 != p2.get();
 }
 // DEPRECATED: Use scoped_ptr<C, base::FreeDeleter> instead.
 //
 // scoped_ptr_malloc<> is similar to scoped_ptr<>, but it accepts a
 // second template argument, the functor used to free the object.
 template<class C, class FreeProc = base::FreeDeleter>
 class scoped_ptr_malloc {
   MOVE_ONLY_TYPE_FOR_CPP_03(scoped_ptr_malloc, RValue)
  public:
   // The element type
   typedef C element_type;
   // Constructor.  Defaults to initializing with NULL.
   // There is no way to create an uninitialized scoped_ptr.
   // The input parameter must be allocated with an allocator that matches the
   // Free functor.  For the default Free functor, this is malloc, calloc, or
   // realloc.
   explicit scoped_ptr_malloc(C* p = NULL): ptr_(p) {}
   // Constructor.  Move constructor for C++03 move emulation of this type.
   scoped_ptr_malloc(RValue rvalue)
       : ptr_(rvalue.object->release()) {
   }
   // Destructor.  If there is a C object, call the Free functor.
   ~scoped_ptr_malloc() {
     reset();
   }
   // operator=.  Move operator= for C++03 move emulation of this type.
   scoped_ptr_malloc& operator=(RValue rhs) {
     reset(rhs.object->release());
     return *this;
   }
   // Reset.  Calls the Free functor on the current owned object, if any.
   // Then takes ownership of a new object, if given.
   // this->reset(this->get()) works.
   void reset(C* p = NULL) {
     if (ptr_ != p) {
       if (ptr_ != NULL) {
         FreeProc free_proc;
         free_proc(ptr_);
       }
       ptr_ = p;
     }
   }
   // Get the current object.
   // operator* and operator-> will cause an assert() failure if there is
   // no current object.
   C& operator*() const {
     assert(ptr_ != NULL);
     return *ptr_;
   }
   C* operator->() const {
     assert(ptr_ != NULL);
     return ptr_;
   }
   C* get() const {
     return ptr_;
   }
   // Allow scoped_ptr_malloc<C> to be used in boolean expressions, but not
   // implicitly convertible to a real bool (which is dangerous).
   typedef C* scoped_ptr_malloc::*Testable;
   operator Testable() const { return ptr_ ? &scoped_ptr_malloc::ptr_ : NULL; }
   // Comparison operators.
   // These return whether a scoped_ptr_malloc and a plain pointer refer
   // to the same object, not just to two different but equal objects.
   // For compatibility with the boost-derived implementation, these
   // take non-const arguments.
   bool operator==(C* p) const {
     return ptr_ == p;
   }
   bool operator!=(C* p) const {
     return ptr_ != p;
   }
   // Swap two scoped pointers.
   void swap(scoped_ptr_malloc & b) {
     C* tmp = b.ptr_;
     b.ptr_ = ptr_;
     ptr_ = tmp;
   }
   // Release a pointer.
   // The return value is the current pointer held by this object.
   // If this object holds a NULL pointer, the return value is NULL.
   // After this operation, this object will hold a NULL pointer,
   // and will not own the object any more.
   C* release() WARN_UNUSED_RESULT {
     C* tmp = ptr_;
     ptr_ = NULL;
     return tmp;
   }
  private:
   C* ptr_;
   // no reason to use these: each scoped_ptr_malloc should have its own object
   template <class C2, class GP>
   bool operator==(scoped_ptr_malloc<C2, GP> const& p) const;
   template <class C2, class GP>
   bool operator!=(scoped_ptr_malloc<C2, GP> const& p) const;
 };
 template<class C, class FP> inline
 void swap(scoped_ptr_malloc<C, FP>& a, scoped_ptr_malloc<C, FP>& b) {
   a.swap(b);
 }
 template<class C, class FP> inline
 bool operator==(C* p, const scoped_ptr_malloc<C, FP>& b) {
   return p == b.get();
 }
 template<class C, class FP> inline
 bool operator!=(C* p, const scoped_ptr_malloc<C, FP>& b) {
   return p != b.get();
 }
 // A function to convert T* into scoped_ptr<T>
 // Doing e.g. make_scoped_ptr(new FooBarBaz<type>(arg)) is a shorter notation
 // for scoped_ptr<FooBarBaz<type> >(new FooBarBaz<type>(arg))
 template <typename T>
 scoped_ptr<T> make_scoped_ptr(T* ptr) {
   return scoped_ptr<T>(ptr);
 }
 #endif  // BASE_MEMORY_SCOPED_PTR_H_

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security/sandbox/chromium/base/memory/scoped_ptr.h@ca08bd8f51b2 (annotated)

security/sandbox/chromium/base/memory/scoped_ptr.h