1 | /* |
2 | * Copyright (C) 2017 Apple Inc. All rights reserved. |
3 | * |
4 | * Redistribution and use in source and binary forms, with or without |
5 | * modification, are permitted provided that the following conditions |
6 | * are met: |
7 | * 1. Redistributions of source code must retain the above copyright |
8 | * notice, this list of conditions and the following disclaimer. |
9 | * 2. Redistributions in binary form must reproduce the above copyright |
10 | * notice, this list of conditions and the following disclaimer in the |
11 | * documentation and/or other materials provided with the distribution. |
12 | * |
13 | * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' |
14 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
15 | * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
16 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS |
17 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
18 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
19 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
20 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
21 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
22 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF |
23 | * THE POSSIBILITY OF SUCH DAMAGE. |
24 | */ |
25 | |
26 | #pragma once |
27 | |
28 | #include <wtf/DumbPtrTraits.h> |
29 | #include <wtf/Gigacage.h> |
30 | #include <wtf/PtrTag.h> |
31 | |
32 | #include <climits> |
33 | |
34 | namespace WTF { |
35 | |
36 | constexpr bool tagCagedPtr = true; |
37 | |
38 | template<Gigacage::Kind passedKind, typename T, bool shouldTag = false, typename PtrTraits = DumbPtrTraits<T>> |
39 | class CagedPtr { |
40 | public: |
41 | static constexpr Gigacage::Kind kind = passedKind; |
42 | |
43 | CagedPtr() : CagedPtr(nullptr) { } |
44 | CagedPtr(std::nullptr_t) |
45 | : m_ptr(shouldTag ? tagArrayPtr<T>(nullptr, 0) : nullptr) |
46 | { } |
47 | |
48 | CagedPtr(T* ptr, unsigned size) |
49 | : m_ptr(shouldTag ? tagArrayPtr(ptr, size) : ptr) |
50 | { } |
51 | |
52 | T* get(unsigned size) const |
53 | { |
54 | ASSERT(m_ptr); |
55 | T* ptr = PtrTraits::unwrap(m_ptr); |
56 | T* cagedPtr = Gigacage::caged(kind, ptr); |
57 | T* untaggedPtr = shouldTag ? untagArrayPtr(mergePointers(ptr, cagedPtr), size) : cagedPtr; |
58 | return untaggedPtr; |
59 | } |
60 | |
61 | T* getMayBeNull(unsigned size) const |
62 | { |
63 | T* ptr = PtrTraits::unwrap(m_ptr); |
64 | T* cagedPtr = Gigacage::cagedMayBeNull(kind, ptr); |
65 | T* untaggedPtr = shouldTag ? untagArrayPtr(mergePointers(ptr, cagedPtr), size) : cagedPtr; |
66 | return untaggedPtr; |
67 | } |
68 | |
69 | T* getUnsafe() const |
70 | { |
71 | T* ptr = PtrTraits::unwrap(m_ptr); |
72 | ptr = shouldTag ? removeArrayPtrTag(ptr) : ptr; |
73 | return Gigacage::cagedMayBeNull(kind, ptr); |
74 | } |
75 | |
76 | // We need the template here so that the type of U is deduced at usage time rather than class time. U should always be T. |
77 | template<typename U = T> |
78 | typename std::enable_if<!std::is_same<void, U>::value, T>::type& |
79 | /* T& */ at(unsigned index, unsigned size) const { return get(size)[index]; } |
80 | |
81 | void recage(unsigned oldSize, unsigned newSize) |
82 | { |
83 | auto ptr = get(oldSize); |
84 | ASSERT(ptr == getUnsafe()); |
85 | *this = CagedPtr(ptr, newSize); |
86 | } |
87 | |
88 | CagedPtr(CagedPtr& other) |
89 | : m_ptr(other.m_ptr) |
90 | { |
91 | } |
92 | |
93 | CagedPtr& operator=(const CagedPtr& ptr) |
94 | { |
95 | m_ptr = ptr.m_ptr; |
96 | return *this; |
97 | } |
98 | |
99 | CagedPtr(CagedPtr&& other) |
100 | : m_ptr(PtrTraits::exchange(other.m_ptr, nullptr)) |
101 | { |
102 | } |
103 | |
104 | CagedPtr& operator=(CagedPtr&& ptr) |
105 | { |
106 | m_ptr = PtrTraits::exchange(ptr.m_ptr, nullptr); |
107 | return *this; |
108 | } |
109 | |
110 | bool operator==(const CagedPtr& other) const |
111 | { |
112 | bool result = m_ptr == other.m_ptr; |
113 | ASSERT(result == (getUnsafe() == other.getUnsafe())); |
114 | return result; |
115 | } |
116 | |
117 | bool operator!=(const CagedPtr& other) const |
118 | { |
119 | return !(*this == other); |
120 | } |
121 | |
122 | explicit operator bool() const |
123 | { |
124 | return getUnsafe() != nullptr; |
125 | } |
126 | |
127 | protected: |
128 | static inline T* mergePointers(T* sourcePtr, T* cagedPtr) |
129 | { |
130 | #if CPU(ARM64E) |
131 | constexpr unsigned numberOfPACBits = 25; |
132 | constexpr uintptr_t mask = (1ull << ((sizeof(T*) * CHAR_BIT) - numberOfPACBits)) - 1; |
133 | return reinterpret_cast<T*>((reinterpret_cast<uintptr_t>(sourcePtr) & ~mask) | (reinterpret_cast<uintptr_t>(cagedPtr) & mask)); |
134 | #else |
135 | UNUSED_PARAM(sourcePtr); |
136 | return cagedPtr; |
137 | #endif |
138 | } |
139 | |
140 | typename PtrTraits::StorageType m_ptr; |
141 | }; |
142 | |
143 | } // namespace WTF |
144 | |
145 | using WTF::CagedPtr; |
146 | using WTF::tagCagedPtr; |
147 | |
148 | |