-
Notifications
You must be signed in to change notification settings - Fork 54
/
ArrayBufferViewObject.h
154 lines (129 loc) · 4.83 KB
/
ArrayBufferViewObject.h
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef vm_ArrayBufferViewObject_h
#define vm_ArrayBufferViewObject_h
#include "builtin/TypedObjectConstants.h"
#include "vm/ArrayBufferObject.h"
#include "vm/NativeObject.h"
#include "vm/SharedArrayObject.h"
#include "vm/SharedMem.h"
namespace js {
/*
* ArrayBufferViewObject
*
* Common base class for all array buffer views (DataViewObject and
* TypedArrayObject).
*/
class ArrayBufferViewObject : public NativeObject {
public:
// Underlying (Shared)ArrayBufferObject.
static constexpr size_t BUFFER_SLOT = 0;
static_assert(BUFFER_SLOT == JS_TYPEDARRAYLAYOUT_BUFFER_SLOT,
"self-hosted code with burned-in constants must get the "
"right buffer slot");
// Slot containing length of the view in number of typed elements.
static constexpr size_t LENGTH_SLOT = 1;
static_assert(LENGTH_SLOT == JS_TYPEDARRAYLAYOUT_LENGTH_SLOT,
"self-hosted code with burned-in constants must get the "
"right length slot");
// Offset of view within underlying (Shared)ArrayBufferObject.
static constexpr size_t BYTEOFFSET_SLOT = 2;
static_assert(BYTEOFFSET_SLOT == JS_TYPEDARRAYLAYOUT_BYTEOFFSET_SLOT,
"self-hosted code with burned-in constants must get the "
"right byteOffset slot");
static constexpr size_t RESERVED_SLOTS = 3;
#ifdef DEBUG
static const uint8_t ZeroLengthArrayData = 0x4A;
#endif
// The raw pointer to the buffer memory, the "private" value.
//
// This offset is exposed for performance reasons - so that it
// need not be looked up on accesses.
static constexpr size_t DATA_SLOT = 3;
private:
void* dataPointerEither_() const {
// Note, do not check whether shared or not
// Keep synced with js::Get<Type>ArrayLengthAndData in jsfriendapi.h!
return static_cast<void*>(getPrivate(DATA_SLOT));
}
public:
MOZ_MUST_USE bool init(JSContext* cx, ArrayBufferObjectMaybeShared* buffer,
uint32_t byteOffset, uint32_t length,
uint32_t bytesPerElement);
static ArrayBufferObjectMaybeShared* bufferObject(
JSContext* cx, Handle<ArrayBufferViewObject*> obj);
void notifyBufferDetached();
void initDataPointer(SharedMem<uint8_t*> viewData) {
// Install a pointer to the buffer location that corresponds
// to offset zero within the typed array.
//
// The following unwrap is safe because the DATA_SLOT is
// accessed only from jitted code and from the
// dataPointerEither_() accessor above; in neither case does the
// raw pointer escape untagged into C++ code.
initPrivate(viewData.unwrap(/*safe - see above*/));
}
SharedMem<void*> dataPointerShared() const {
return SharedMem<void*>::shared(dataPointerEither_());
}
SharedMem<void*> dataPointerEither() const {
if (isSharedMemory()) {
return SharedMem<void*>::shared(dataPointerEither_());
}
return SharedMem<void*>::unshared(dataPointerEither_());
}
void* dataPointerUnshared() const {
MOZ_ASSERT(!isSharedMemory());
return dataPointerEither_();
}
static Value bufferValue(const ArrayBufferViewObject* view) {
return view->getFixedSlot(BUFFER_SLOT);
}
bool hasBuffer() const { return bufferValue(this).isObject(); }
ArrayBufferObject* bufferUnshared() const {
MOZ_ASSERT(!isSharedMemory());
ArrayBufferObjectMaybeShared* obj = bufferEither();
if (!obj) {
return nullptr;
}
return &obj->as<ArrayBufferObject>();
}
SharedArrayBufferObject* bufferShared() const {
MOZ_ASSERT(isSharedMemory());
ArrayBufferObjectMaybeShared* obj = bufferEither();
if (!obj) {
return nullptr;
}
return &obj->as<SharedArrayBufferObject>();
}
ArrayBufferObjectMaybeShared* bufferEither() const {
JSObject* obj = bufferValue(this).toObjectOrNull();
if (!obj) {
return nullptr;
}
MOZ_ASSERT(isSharedMemory() ? obj->is<SharedArrayBufferObject>()
: obj->is<ArrayBufferObject>());
return &obj->as<ArrayBufferObjectMaybeShared>();
}
bool hasDetachedBuffer() const {
// Shared buffers can't be detached.
if (isSharedMemory()) {
return false;
}
// A typed array with a null buffer has never had its buffer exposed to
// become detached.
ArrayBufferObject* buffer = bufferUnshared();
if (!buffer) {
return false;
}
return buffer->isDetached();
}
static void trace(JSTracer* trc, JSObject* obj);
};
} // namespace js
template <>
bool JSObject::is<js::ArrayBufferViewObject>() const;
#endif // vm_ArrayBufferViewObject_h