1 //
2 // Copyright (c) 2019 Apple, Inc. All rights reserved.
3 //
4 // @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 //
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27 //
28
29 #ifndef XNU_LIBKERN_LIBKERN_CXX_OS_SHARED_PTR_H
30 #define XNU_LIBKERN_LIBKERN_CXX_OS_SHARED_PTR_H
31
32 #include <libkern/c++/intrusive_shared_ptr.h>
33 #include <libkern/c++/OSMetaClass.h>
34
35 struct intrusive_osobject_retainer {
36 static void
retainintrusive_osobject_retainer37 retain(OSMetaClassBase const& obj)
38 {
39 obj.retain();
40 }
41 static void
releaseintrusive_osobject_retainer42 release(OSMetaClassBase const& obj)
43 {
44 obj.release();
45 }
46 };
47
48 template <typename Tag>
49 struct intrusive_tagged_osobject_retainer {
50 static void
retainintrusive_tagged_osobject_retainer51 retain(OSMetaClassBase const& obj)
52 {
53 obj.taggedRetain(OSTypeID(Tag));
54 }
55 static void
releaseintrusive_tagged_osobject_retainer56 release(OSMetaClassBase const& obj)
57 {
58 obj.taggedRelease(OSTypeID(Tag));
59 }
60 };
61
62 inline constexpr auto OSNoRetain = libkern::no_retain;
63 inline constexpr auto OSRetain = libkern::retain;
64
65 template <typename T>
66 class __attribute__((trivial_abi)) OSSharedPtr: public libkern::intrusive_shared_ptr<T, intrusive_osobject_retainer> {
67 using libkern::intrusive_shared_ptr<T, intrusive_osobject_retainer>::intrusive_shared_ptr;
68 };
69
70 template <typename T, typename Tag>
71 class __attribute__((trivial_abi)) OSTaggedSharedPtr: public libkern::intrusive_shared_ptr<T, intrusive_tagged_osobject_retainer<Tag> > {
72 using libkern::intrusive_shared_ptr<T, intrusive_tagged_osobject_retainer<Tag> >::intrusive_shared_ptr;
73 };
74
75 template <typename T>
76 OSSharedPtr<T>
OSMakeShared()77 OSMakeShared()
78 {
79 T* memory = OSTypeAlloc(T);
80 // OSTypeAlloc returns an object with a refcount of 1, so we must not
81 // retain when constructing the shared pointer.
82 return OSSharedPtr<T>(memory, OSNoRetain);
83 }
84
85 template <typename Destination, typename Source>
86 OSSharedPtr<Destination>
OSDynamicPtrCast(OSSharedPtr<Source> const & source)87 OSDynamicPtrCast(OSSharedPtr<Source> const& source)
88 {
89 Destination* raw = OSDynamicCast(Destination, source.get());
90 if (raw == nullptr) {
91 return nullptr;
92 } else {
93 OSSharedPtr<Destination> dest(raw, OSRetain);
94 return dest;
95 }
96 }
97
98 template <typename Destination, typename Source>
99 OSSharedPtr<Destination>
OSDynamicPtrCast(OSSharedPtr<Source> && source)100 OSDynamicPtrCast(OSSharedPtr<Source> && source)
101 {
102 Destination* raw = OSDynamicCast(Destination, source.get());
103 if (raw == nullptr) {
104 return nullptr;
105 } else {
106 OSSharedPtr<Destination> dest(raw, OSNoRetain);
107 source.detach(); // we stole the retain!
108 return dest;
109 }
110 }
111
112 template <typename Destination, typename Tag, typename Source>
113 OSTaggedSharedPtr<Destination, Tag>
OSDynamicPtrCast(OSTaggedSharedPtr<Source,Tag> const & source)114 OSDynamicPtrCast(OSTaggedSharedPtr<Source, Tag> const& source)
115 {
116 Destination* raw = OSDynamicCast(Destination, source.get());
117 if (raw == nullptr) {
118 return nullptr;
119 } else {
120 OSTaggedSharedPtr<Destination, Tag> dest(raw, OSRetain);
121 return dest;
122 }
123 }
124
125 template <typename To, typename From>
126 OSSharedPtr<To>
OSStaticPtrCast(OSSharedPtr<From> const & ptr)127 OSStaticPtrCast(OSSharedPtr<From> const& ptr) noexcept
128 {
129 return OSSharedPtr<To>(static_cast<To*>(ptr.get()), OSRetain);
130 }
131
132 template <typename To, typename From>
133 OSSharedPtr<To>
OSStaticPtrCast(OSSharedPtr<From> && ptr)134 OSStaticPtrCast(OSSharedPtr<From>&& ptr) noexcept
135 {
136 return OSSharedPtr<To>(static_cast<To*>(ptr.detach()), OSNoRetain);
137 }
138
139 template <typename To, typename From>
140 OSSharedPtr<To>
OSConstPtrCast(OSSharedPtr<From> const & ptr)141 OSConstPtrCast(OSSharedPtr<From> const& ptr) noexcept
142 {
143 return OSSharedPtr<To>(const_cast<To*>(ptr.get()), OSRetain);
144 }
145
146 template <typename To, typename From>
147 OSSharedPtr<To>
OSConstPtrCast(OSSharedPtr<From> && ptr)148 OSConstPtrCast(OSSharedPtr<From>&& ptr) noexcept
149 {
150 return OSSharedPtr<To>(const_cast<To*>(ptr.detach()), OSNoRetain);
151 }
152
153 #endif // !XNU_LIBKERN_LIBKERN_CXX_OS_SHARED_PTR_H
154