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