gecko-dev/js/public/StructuredClone.h

248 lines
10 KiB
C++

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