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248 lines
10 KiB
C++
248 lines
10 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* vim: set ts=8 sts=4 et sw=4 tw=99:
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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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#ifndef js_StructuredClone_h
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#define js_StructuredClone_h
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#include "mozilla/NullPtr.h"
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#include <stdint.h>
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#include "jstypes.h"
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#include "js/RootingAPI.h"
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#include "js/TypeDecls.h"
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#include "js/Value.h"
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struct JSRuntime;
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struct JSStructuredCloneReader;
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struct JSStructuredCloneWriter;
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// API for the HTML5 internal structured cloning algorithm.
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namespace JS {
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enum TransferableOwnership {
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// Transferable data has not been filled in yet
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SCTAG_TMO_UNFILLED = 0,
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// Structured clone buffer does not yet own the data
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SCTAG_TMO_UNOWNED = 1,
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// All values at least this large are owned by the clone buffer
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SCTAG_TMO_FIRST_OWNED = 2,
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// Data is a pointer that can be freed
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SCTAG_TMO_ALLOC_DATA = 2,
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// Data is a SharedArrayBufferObject's buffer
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SCTAG_TMO_SHARED_BUFFER = 3,
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// Data is a memory mapped pointer
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SCTAG_TMO_MAPPED_DATA = 4,
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// Data is embedding-specific. The engine can free it by calling the
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// freeTransfer op. The embedding can also use SCTAG_TMO_USER_MIN and
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// greater, up to 32 bits, to distinguish specific ownership variants.
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SCTAG_TMO_CUSTOM = 5,
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SCTAG_TMO_USER_MIN
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};
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} /* namespace JS */
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// Read structured data from the reader r. This hook is used to read a value
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// previously serialized by a call to the WriteStructuredCloneOp hook.
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//
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// tag and data are the pair of uint32_t values from the header. The callback
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// may use the JS_Read* APIs to read any other relevant parts of the object
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// from the reader r. closure is any value passed to the JS_ReadStructuredClone
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// function. Return the new object on success, nullptr on error/exception.
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typedef JSObject *(*ReadStructuredCloneOp)(JSContext *cx, JSStructuredCloneReader *r,
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uint32_t tag, uint32_t data, void *closure);
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// Structured data serialization hook. The engine can write primitive values,
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// Objects, Arrays, Dates, RegExps, TypedArrays, ArrayBuffers, Sets, Maps,
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// and SharedTypedArrays. Any other type of object requires application support.
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// This callback must first use the JS_WriteUint32Pair API to write an object
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// header, passing a value greater than JS_SCTAG_USER to the tag parameter.
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// Then it can use the JS_Write* APIs to write any other relevant parts of
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// the value v to the writer w. closure is any value passed to the
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// JS_WriteStructuredClone function.
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//
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// Return true on success, false on error/exception.
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typedef bool (*WriteStructuredCloneOp)(JSContext *cx, JSStructuredCloneWriter *w,
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JS::HandleObject obj, void *closure);
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// This is called when JS_WriteStructuredClone is given an invalid transferable.
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// To follow HTML5, the application must throw a DATA_CLONE_ERR DOMException
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// with error set to one of the JS_SCERR_* values.
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typedef void (*StructuredCloneErrorOp)(JSContext *cx, uint32_t errorid);
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// This is called when JS_ReadStructuredClone receives a transferable object
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// not known to the engine. If this hook does not exist or returns false, the
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// JS engine calls the reportError op if set, otherwise it throws a
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// DATA_CLONE_ERR DOM Exception. This method is called before any other
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// callback and must return a non-null object in returnObject on success.
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typedef bool (*ReadTransferStructuredCloneOp)(JSContext *cx, JSStructuredCloneReader *r,
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uint32_t tag, void *content, uint64_t extraData,
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void *closure,
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JS::MutableHandleObject returnObject);
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// Called when JS_WriteStructuredClone receives a transferable object not
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// handled by the engine. If this hook does not exist or returns false, the JS
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// engine will call the reportError hook or fall back to throwing a
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// DATA_CLONE_ERR DOM Exception. This method is called before any other
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// callback.
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//
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// tag: indicates what type of transferable this is. Must be greater than
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// 0xFFFF0201 (value of the internal SCTAG_TRANSFER_MAP_PENDING_ENTRY)
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//
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// ownership: see TransferableOwnership, above. Used to communicate any needed
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// ownership info to the FreeTransferStructuredCloneOp.
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//
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// content, extraData: what the ReadTransferStructuredCloneOp will receive
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//
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typedef bool (*TransferStructuredCloneOp)(JSContext *cx,
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JS::Handle<JSObject*> obj,
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void *closure,
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// Output:
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uint32_t *tag,
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JS::TransferableOwnership *ownership,
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void **content,
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uint64_t *extraData);
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// Called when JS_ClearStructuredClone has to free an unknown transferable
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// object. Note that it should never trigger a garbage collection (and will
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// assert in a debug build if it does.)
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typedef void (*FreeTransferStructuredCloneOp)(uint32_t tag, JS::TransferableOwnership ownership,
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void *content, uint64_t extraData, void *closure);
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// The maximum supported structured-clone serialization format version.
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// Increment this when anything at all changes in the serialization format.
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// (Note that this does not need to be bumped for Transferable-only changes,
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// since they are never saved to persistent storage.)
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#define JS_STRUCTURED_CLONE_VERSION 5
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struct JSStructuredCloneCallbacks {
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ReadStructuredCloneOp read;
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WriteStructuredCloneOp write;
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StructuredCloneErrorOp reportError;
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ReadTransferStructuredCloneOp readTransfer;
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TransferStructuredCloneOp writeTransfer;
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FreeTransferStructuredCloneOp freeTransfer;
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};
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// Note: if the *data contains transferable objects, it can be read only once.
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JS_PUBLIC_API(bool)
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JS_ReadStructuredClone(JSContext *cx, uint64_t *data, size_t nbytes, uint32_t version,
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JS::MutableHandleValue vp,
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const JSStructuredCloneCallbacks *optionalCallbacks, void *closure);
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// Note: On success, the caller is responsible for calling
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// JS_ClearStructuredClone(*datap, nbytes, optionalCallbacks, closure).
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JS_PUBLIC_API(bool)
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JS_WriteStructuredClone(JSContext *cx, JS::HandleValue v, uint64_t **datap, size_t *nbytesp,
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const JSStructuredCloneCallbacks *optionalCallbacks,
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void *closure, JS::HandleValue transferable);
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JS_PUBLIC_API(bool)
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JS_ClearStructuredClone(uint64_t *data, size_t nbytes,
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const JSStructuredCloneCallbacks *optionalCallbacks,
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void *closure);
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JS_PUBLIC_API(bool)
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JS_StructuredCloneHasTransferables(const uint64_t *data, size_t nbytes, bool *hasTransferable);
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JS_PUBLIC_API(bool)
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JS_StructuredClone(JSContext *cx, JS::HandleValue v, JS::MutableHandleValue vp,
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const JSStructuredCloneCallbacks *optionalCallbacks, void *closure);
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// RAII sugar for JS_WriteStructuredClone.
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class JS_PUBLIC_API(JSAutoStructuredCloneBuffer) {
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uint64_t *data_;
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size_t nbytes_;
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uint32_t version_;
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const JSStructuredCloneCallbacks *callbacks_;
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void *closure_;
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public:
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JSAutoStructuredCloneBuffer()
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: data_(nullptr), nbytes_(0), version_(JS_STRUCTURED_CLONE_VERSION),
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callbacks_(nullptr), closure_(nullptr)
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{}
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JSAutoStructuredCloneBuffer(const JSStructuredCloneCallbacks *callbacks, void *closure)
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: data_(nullptr), nbytes_(0), version_(JS_STRUCTURED_CLONE_VERSION),
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callbacks_(callbacks), closure_(closure)
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{}
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JSAutoStructuredCloneBuffer(JSAutoStructuredCloneBuffer &&other);
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JSAutoStructuredCloneBuffer &operator=(JSAutoStructuredCloneBuffer &&other);
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~JSAutoStructuredCloneBuffer() { clear(); }
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uint64_t *data() const { return data_; }
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size_t nbytes() const { return nbytes_; }
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void clear();
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// Copy some memory. It will be automatically freed by the destructor.
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bool copy(const uint64_t *data, size_t nbytes, uint32_t version=JS_STRUCTURED_CLONE_VERSION);
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// Adopt some memory. It will be automatically freed by the destructor.
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// data must have been allocated by the JS engine (e.g., extracted via
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// JSAutoStructuredCloneBuffer::steal).
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void adopt(uint64_t *data, size_t nbytes, uint32_t version=JS_STRUCTURED_CLONE_VERSION);
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// Remove the buffer so that it will not be automatically freed.
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// After this, the caller is responsible for feeding the memory back to
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// JSAutoStructuredCloneBuffer::adopt.
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void steal(uint64_t **datap, size_t *nbytesp, uint32_t *versionp=nullptr);
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bool read(JSContext *cx, JS::MutableHandleValue vp,
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const JSStructuredCloneCallbacks *optionalCallbacks=nullptr, void *closure=nullptr);
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bool write(JSContext *cx, JS::HandleValue v,
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const JSStructuredCloneCallbacks *optionalCallbacks=nullptr, void *closure=nullptr);
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bool write(JSContext *cx, JS::HandleValue v, JS::HandleValue transferable,
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const JSStructuredCloneCallbacks *optionalCallbacks=nullptr, void *closure=nullptr);
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private:
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// Copy and assignment are not supported.
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JSAutoStructuredCloneBuffer(const JSAutoStructuredCloneBuffer &other) MOZ_DELETE;
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JSAutoStructuredCloneBuffer &operator=(const JSAutoStructuredCloneBuffer &other) MOZ_DELETE;
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};
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// The range of tag values the application may use for its own custom object types.
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#define JS_SCTAG_USER_MIN ((uint32_t) 0xFFFF8000)
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#define JS_SCTAG_USER_MAX ((uint32_t) 0xFFFFFFFF)
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#define JS_SCERR_RECURSION 0
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#define JS_SCERR_TRANSFERABLE 1
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JS_PUBLIC_API(void)
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JS_SetStructuredCloneCallbacks(JSRuntime *rt, const JSStructuredCloneCallbacks *callbacks);
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JS_PUBLIC_API(bool)
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JS_ReadUint32Pair(JSStructuredCloneReader *r, uint32_t *p1, uint32_t *p2);
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JS_PUBLIC_API(bool)
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JS_ReadBytes(JSStructuredCloneReader *r, void *p, size_t len);
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JS_PUBLIC_API(bool)
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JS_ReadTypedArray(JSStructuredCloneReader *r, JS::MutableHandleValue vp);
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JS_PUBLIC_API(bool)
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JS_WriteUint32Pair(JSStructuredCloneWriter *w, uint32_t tag, uint32_t data);
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JS_PUBLIC_API(bool)
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JS_WriteBytes(JSStructuredCloneWriter *w, const void *p, size_t len);
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JS_PUBLIC_API(bool)
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JS_WriteTypedArray(JSStructuredCloneWriter *w, JS::HandleValue v);
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#endif /* js_StructuredClone_h */
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