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Diffstat (limited to '')
-rw-r--r-- | js/public/ArrayBufferMaybeShared.h | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/js/public/ArrayBufferMaybeShared.h b/js/public/ArrayBufferMaybeShared.h new file mode 100644 index 0000000000..2a972c96a4 --- /dev/null +++ b/js/public/ArrayBufferMaybeShared.h @@ -0,0 +1,109 @@ +/* -*- 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, size_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&); + +/** + * Returns whether the passed array buffer is 'large': its byteLength >= 2 GB. + * + * |obj| must pass a JS::IsArrayBufferObjectMaybeShared test. + */ +extern JS_PUBLIC_API bool IsLargeArrayBufferMaybeShared(JSObject* obj); + +/** + * Returns whether the passed array buffer is resizable or growable for shared + * array buffers. + * + * |obj| must pass a JS::IsArrayBufferObjectMaybeShared test. + */ +extern JS_PUBLIC_API bool IsResizableArrayBufferMaybeShared(JSObject* obj); + +} // namespace JS + +#endif /* js_ArrayBufferMaybeShared_h */ |