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103 lines
3.9 KiB
C++
103 lines
3.9 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/**
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* Functions for working with either ArrayBuffer or SharedArrayBuffer objects
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* in agnostic fashion.
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*/
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#ifndef js_ArrayBufferMaybeShared_h
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#define js_ArrayBufferMaybeShared_h
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#include <stdint.h> // uint8_t, uint32_t
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#include "jstypes.h" // JS_PUBLIC_API
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struct JS_PUBLIC_API JSContext;
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class JS_PUBLIC_API JSObject;
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namespace JS {
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class JS_PUBLIC_API AutoRequireNoGC;
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// TYPE TESTING
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/**
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* Check whether obj supports the JS::GetArrayBufferMaybeShared* APIs. Note
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* that this may return false if a security wrapper is encountered that denies
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* the unwrapping. If this test succeeds, then it is safe to call the various
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* predicate and accessor JSAPI calls defined below.
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*/
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extern JS_PUBLIC_API bool IsArrayBufferObjectMaybeShared(JSObject* obj);
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// ACCESSORS
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/*
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* Test for ArrayBufferMaybeShared subtypes and return the unwrapped object if
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* so, else nullptr. Never throws.
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*/
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extern JS_PUBLIC_API JSObject* UnwrapArrayBufferMaybeShared(JSObject* obj);
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/**
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* Get the length, sharedness, and data from an ArrayBufferMaybeShared subtypes.
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*
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* The computed length and data pointer may be invalidated by a GC or by an
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* unshared array buffer becoming detached. Callers must take care not to
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* perform any actions that could trigger a GC or result in an unshared array
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* buffer becoming detached. If such actions nonetheless must be performed,
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* callers should perform this call a second time (and sensibly handle results
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* that may be different from those returned the first time). (Sharedness is an
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* immutable characteristic of an array buffer or shared array buffer, so that
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* boolean remains valid across GC or detaching.)
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*
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* |obj| must be an ArrayBufferMaybeShared subtype: an ArrayBuffer or a
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* SharedArrayBuffer.
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*
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* |*length| will be set to bytes in the buffer.
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*
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* |*isSharedMemory| will be set to true if it is a SharedArrayBuffer, otherwise
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* to false.
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*
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* |*data| will be set to a pointer to the bytes in the buffer.
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*/
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extern JS_PUBLIC_API void GetArrayBufferMaybeSharedLengthAndData(
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JSObject* obj, size_t* length, bool* isSharedMemory, uint8_t** data);
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/**
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* Return a pointer to the start of the array buffer's data, and indicate
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* whether the data is from a shared array buffer through an outparam.
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*
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* The returned data pointer may be invalidated by a GC or by an unshared array
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* buffer becoming detached. Callers must take care not to perform any actions
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* that could trigger a GC or result in an unshared array buffer becoming
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* detached. If such actions nonetheless must be performed, callers should
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* perform this call a second time (and sensibly handle results that may be
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* different from those returned the first time). (Sharedness is an immutable
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* characteristic of an array buffer or shared array buffer, so that boolean
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* remains valid across GC or detaching.)
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*
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* |obj| must have passed a JS::IsArrayBufferObjectMaybeShared test, or somehow
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* be known that it would pass such a test: it is an ArrayBuffer or
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* SharedArrayBuffer or a wrapper of an ArrayBuffer/SharedArrayBuffer, and the
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* unwrapping will succeed.
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*
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* |*isSharedMemory| will be set to true if the typed array maps a
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* SharedArrayBuffer, otherwise to false.
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*/
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extern JS_PUBLIC_API uint8_t* GetArrayBufferMaybeSharedData(
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JSObject* obj, bool* isSharedMemory, const AutoRequireNoGC&);
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/**
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* Returns whether the passed array buffer is 'large': its byteLength >= 2 GB.
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* See also SetLargeArrayBuffersEnabled.
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*
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* |obj| must pass a JS::IsArrayBufferObjectMaybeShared test.
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*/
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extern JS_FRIEND_API bool IsLargeArrayBufferMaybeShared(JSObject* obj);
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} // namespace JS
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#endif /* js_ArrayBufferMaybeShared_h */
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