script/dom/bindings/
structuredclone.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5//! This module implements structured cloning, as defined by [HTML](https://html.spec.whatwg.org/multipage/#safe-passing-of-structured-data).
6
7use std::ffi::CStr;
8use std::os::raw;
9use std::ptr;
10
11use base::id::{
12    BlobId, DomExceptionId, DomMatrixId, DomPointId, DomQuadId, DomRectId, ImageBitmapId, Index,
13    MessagePortId, NamespaceIndex, OffscreenCanvasId, PipelineNamespaceId, QuotaExceededErrorId,
14};
15use constellation_traits::{
16    BlobImpl, DomException, DomMatrix, DomPoint, DomQuad, DomRect, MessagePortImpl,
17    Serializable as SerializableInterface, SerializableImageBitmap, SerializableQuotaExceededError,
18    StructuredSerializedData, TransferableOffscreenCanvas, Transferrable as TransferrableInterface,
19    TransformStreamData,
20};
21use js::gc::RootedVec;
22use js::glue::{
23    CopyJSStructuredCloneData, GetLengthOfJSStructuredCloneData, WriteBytesToJSStructuredCloneData,
24};
25use js::jsapi::{
26    CloneDataPolicy, HandleObject as RawHandleObject, Heap, JS_IsExceptionPending,
27    JS_ReadUint32Pair, JS_STRUCTURED_CLONE_VERSION, JS_WriteUint32Pair, JSContext, JSObject,
28    JSStructuredCloneCallbacks, JSStructuredCloneReader, JSStructuredCloneWriter,
29    MutableHandleObject as RawMutableHandleObject, StructuredCloneScope, TransferableOwnership,
30};
31use js::jsval::UndefinedValue;
32use js::rust::wrappers::{JS_ReadStructuredClone, JS_WriteStructuredClone};
33use js::rust::{
34    CustomAutoRooterGuard, HandleValue, JSAutoStructuredCloneBufferWrapper, MutableHandleValue,
35};
36use rustc_hash::FxHashMap;
37use script_bindings::conversions::{IDLInterface, SafeToJSValConvertible};
38use strum::IntoEnumIterator;
39
40use crate::dom::bindings::conversions::root_from_object;
41use crate::dom::bindings::error::{Error, Fallible};
42use crate::dom::bindings::root::DomRoot;
43use crate::dom::bindings::serializable::{Serializable, StorageKey};
44use crate::dom::bindings::transferable::Transferable;
45use crate::dom::blob::Blob;
46use crate::dom::dompoint::DOMPoint;
47use crate::dom::dompointreadonly::DOMPointReadOnly;
48use crate::dom::globalscope::GlobalScope;
49use crate::dom::imagebitmap::ImageBitmap;
50use crate::dom::messageport::MessagePort;
51use crate::dom::offscreencanvas::OffscreenCanvas;
52use crate::dom::readablestream::ReadableStream;
53use crate::dom::types::{
54    DOMException, DOMMatrix, DOMMatrixReadOnly, DOMQuad, DOMRect, DOMRectReadOnly,
55    QuotaExceededError, TransformStream,
56};
57use crate::dom::writablestream::WritableStream;
58use crate::realms::{AlreadyInRealm, InRealm, enter_realm};
59use crate::script_runtime::{CanGc, JSContext as SafeJSContext};
60
61// TODO: Should we add Min and Max const to https://github.com/servo/rust-mozjs/blob/master/src/consts.rs?
62// TODO: Determine for sure which value Min and Max should have.
63// NOTE: Current values found at https://dxr.mozilla.org/mozilla-central/
64// rev/ff04d410e74b69acfab17ef7e73e7397602d5a68/js/public/StructuredClone.h#323
65#[repr(u32)]
66pub(super) enum StructuredCloneTags {
67    /// To support additional types, add new tags with values incremented from the last one before Max.
68    Min = 0xFFFF8000,
69    DomBlob = 0xFFFF8001,
70    MessagePort = 0xFFFF8002,
71    Principals = 0xFFFF8003,
72    DomPointReadOnly = 0xFFFF8004,
73    DomPoint = 0xFFFF8005,
74    ReadableStream = 0xFFFF8006,
75    DomException = 0xFFFF8007,
76    WritableStream = 0xFFFF8008,
77    TransformStream = 0xFFFF8009,
78    ImageBitmap = 0xFFFF800A,
79    OffscreenCanvas = 0xFFFF800B,
80    QuotaExceededError = 0xFFFF800C,
81    DomRect = 0xFFFF800D,
82    DomRectReadOnly = 0xFFFF800E,
83    DomQuad = 0xFFFF800F,
84    DomMatrix = 0xFFFF8010,
85    DomMatrixReadOnly = 0xFFFF8011,
86    Max = 0xFFFFFFFF,
87}
88
89impl From<SerializableInterface> for StructuredCloneTags {
90    fn from(v: SerializableInterface) -> Self {
91        match v {
92            SerializableInterface::Blob => StructuredCloneTags::DomBlob,
93            SerializableInterface::DomPoint => StructuredCloneTags::DomPoint,
94            SerializableInterface::DomPointReadOnly => StructuredCloneTags::DomPointReadOnly,
95            SerializableInterface::DomRect => StructuredCloneTags::DomRect,
96            SerializableInterface::DomRectReadOnly => StructuredCloneTags::DomRectReadOnly,
97            SerializableInterface::DomQuad => StructuredCloneTags::DomQuad,
98            SerializableInterface::DomMatrix => StructuredCloneTags::DomMatrix,
99            SerializableInterface::DomMatrixReadOnly => StructuredCloneTags::DomMatrixReadOnly,
100            SerializableInterface::DomException => StructuredCloneTags::DomException,
101            SerializableInterface::ImageBitmap => StructuredCloneTags::ImageBitmap,
102            SerializableInterface::QuotaExceededError => StructuredCloneTags::QuotaExceededError,
103        }
104    }
105}
106
107impl From<TransferrableInterface> for StructuredCloneTags {
108    fn from(v: TransferrableInterface) -> Self {
109        match v {
110            TransferrableInterface::ImageBitmap => StructuredCloneTags::ImageBitmap,
111            TransferrableInterface::MessagePort => StructuredCloneTags::MessagePort,
112            TransferrableInterface::OffscreenCanvas => StructuredCloneTags::OffscreenCanvas,
113            TransferrableInterface::ReadableStream => StructuredCloneTags::ReadableStream,
114            TransferrableInterface::WritableStream => StructuredCloneTags::WritableStream,
115            TransferrableInterface::TransformStream => StructuredCloneTags::TransformStream,
116        }
117    }
118}
119
120fn reader_for_type(
121    val: SerializableInterface,
122) -> unsafe fn(
123    &GlobalScope,
124    *mut JSStructuredCloneReader,
125    &mut StructuredDataReader<'_>,
126    CanGc,
127) -> *mut JSObject {
128    match val {
129        SerializableInterface::Blob => read_object::<Blob>,
130        SerializableInterface::DomPoint => read_object::<DOMPoint>,
131        SerializableInterface::DomPointReadOnly => read_object::<DOMPointReadOnly>,
132        SerializableInterface::DomRect => read_object::<DOMRect>,
133        SerializableInterface::DomRectReadOnly => read_object::<DOMRectReadOnly>,
134        SerializableInterface::DomQuad => read_object::<DOMQuad>,
135        SerializableInterface::DomMatrix => read_object::<DOMMatrix>,
136        SerializableInterface::DomMatrixReadOnly => read_object::<DOMMatrixReadOnly>,
137        SerializableInterface::DomException => read_object::<DOMException>,
138        SerializableInterface::ImageBitmap => read_object::<ImageBitmap>,
139        SerializableInterface::QuotaExceededError => read_object::<QuotaExceededError>,
140    }
141}
142
143unsafe fn read_object<T: Serializable>(
144    owner: &GlobalScope,
145    r: *mut JSStructuredCloneReader,
146    sc_reader: &mut StructuredDataReader<'_>,
147    can_gc: CanGc,
148) -> *mut JSObject {
149    let mut name_space: u32 = 0;
150    let mut index: u32 = 0;
151    unsafe {
152        assert!(JS_ReadUint32Pair(
153            r,
154            &mut name_space as *mut u32,
155            &mut index as *mut u32
156        ));
157    }
158    let storage_key = StorageKey { index, name_space };
159
160    // 1. Re-build the key for the storage location
161    // of the serialized object.
162    let id: NamespaceIndex<T::Index> = storage_key.into();
163
164    // 2. Get the transferred object from its storage, using the key.
165    let objects = T::serialized_storage(StructuredData::Reader(sc_reader));
166    let objects_map = objects
167        .as_mut()
168        .expect("The SC holder does not have any relevant objects");
169    let serialized = objects_map
170        .remove(&id)
171        .expect("No object to be deserialized found.");
172    if objects_map.is_empty() {
173        *objects = None;
174    }
175
176    if let Ok(obj) = T::deserialize(owner, serialized, can_gc) {
177        let reflector = obj.reflector().get_jsobject().get();
178        sc_reader.roots.push(Heap::boxed(reflector));
179        return reflector;
180    }
181    warn!("Reading structured data failed in {:?}.", owner.get_url());
182    ptr::null_mut()
183}
184
185unsafe fn write_object<T: Serializable>(
186    interface: SerializableInterface,
187    owner: &GlobalScope,
188    object: &T,
189    w: *mut JSStructuredCloneWriter,
190    sc_writer: &mut StructuredDataWriter,
191) -> bool {
192    if let Ok((new_id, serialized)) = object.serialize() {
193        let objects = T::serialized_storage(StructuredData::Writer(sc_writer))
194            .get_or_insert(FxHashMap::default());
195        objects.insert(new_id, serialized);
196        let storage_key = StorageKey::new(new_id);
197
198        unsafe {
199            assert!(JS_WriteUint32Pair(
200                w,
201                StructuredCloneTags::from(interface) as u32,
202                0
203            ));
204            assert!(JS_WriteUint32Pair(
205                w,
206                storage_key.name_space,
207                storage_key.index
208            ));
209        }
210        return true;
211    }
212    warn!("Writing structured data failed in {:?}.", owner.get_url());
213    false
214}
215
216unsafe extern "C" fn read_callback(
217    cx: *mut JSContext,
218    r: *mut JSStructuredCloneReader,
219    _policy: *const CloneDataPolicy,
220    tag: u32,
221    _data: u32,
222    closure: *mut raw::c_void,
223) -> *mut JSObject {
224    assert!(
225        tag < StructuredCloneTags::Max as u32,
226        "tag should be lower than StructuredCloneTags::Max"
227    );
228    assert!(
229        tag > StructuredCloneTags::Min as u32,
230        "tag should be higher than StructuredCloneTags::Min"
231    );
232
233    unsafe {
234        let sc_reader = &mut *(closure as *mut StructuredDataReader<'_>);
235        let in_realm_proof = AlreadyInRealm::assert_for_cx(SafeJSContext::from_ptr(cx));
236        let global = GlobalScope::from_context(cx, InRealm::Already(&in_realm_proof));
237        for serializable in SerializableInterface::iter() {
238            if tag == StructuredCloneTags::from(serializable) as u32 {
239                let reader = reader_for_type(serializable);
240                return reader(&global, r, sc_reader, CanGc::note());
241            }
242        }
243    }
244
245    ptr::null_mut()
246}
247
248enum OperationError {
249    InterfaceDoesNotMatch,
250    Exception(Error),
251}
252
253unsafe fn try_serialize<T: Serializable + IDLInterface>(
254    val: SerializableInterface,
255    cx: *mut JSContext,
256    object: RawHandleObject,
257    global: &GlobalScope,
258    w: *mut JSStructuredCloneWriter,
259    writer: &mut StructuredDataWriter,
260) -> Result<bool, OperationError> {
261    let object = unsafe { root_from_object::<T>(*object, cx) };
262    if let Ok(obj) = object {
263        return unsafe { Ok(write_object(val, global, &*obj, w, writer)) };
264    }
265    Err(OperationError::InterfaceDoesNotMatch)
266}
267
268type SerializeOperation = unsafe fn(
269    SerializableInterface,
270    *mut JSContext,
271    RawHandleObject,
272    &GlobalScope,
273    *mut JSStructuredCloneWriter,
274    &mut StructuredDataWriter,
275) -> Result<bool, OperationError>;
276
277fn serialize_for_type(val: SerializableInterface) -> SerializeOperation {
278    match val {
279        SerializableInterface::Blob => try_serialize::<Blob>,
280        SerializableInterface::DomPoint => try_serialize::<DOMPoint>,
281        SerializableInterface::DomPointReadOnly => try_serialize::<DOMPointReadOnly>,
282        SerializableInterface::DomRect => try_serialize::<DOMRect>,
283        SerializableInterface::DomRectReadOnly => try_serialize::<DOMRectReadOnly>,
284        SerializableInterface::DomQuad => try_serialize::<DOMQuad>,
285        SerializableInterface::DomMatrix => try_serialize::<DOMMatrix>,
286        SerializableInterface::DomMatrixReadOnly => try_serialize::<DOMMatrixReadOnly>,
287        SerializableInterface::DomException => try_serialize::<DOMException>,
288        SerializableInterface::ImageBitmap => try_serialize::<ImageBitmap>,
289        SerializableInterface::QuotaExceededError => try_serialize::<QuotaExceededError>,
290    }
291}
292
293unsafe extern "C" fn write_callback(
294    cx: *mut JSContext,
295    w: *mut JSStructuredCloneWriter,
296    obj: RawHandleObject,
297    _same_process_scope_required: *mut bool,
298    closure: *mut raw::c_void,
299) -> bool {
300    unsafe {
301        let sc_writer = &mut *(closure as *mut StructuredDataWriter);
302        let in_realm_proof = AlreadyInRealm::assert_for_cx(SafeJSContext::from_ptr(cx));
303        let global = GlobalScope::from_context(cx, InRealm::Already(&in_realm_proof));
304        for serializable in SerializableInterface::iter() {
305            let serializer = serialize_for_type(serializable);
306            if let Ok(result) = serializer(serializable, cx, obj, &global, w, sc_writer) {
307                return result;
308            }
309        }
310    }
311    false
312}
313
314fn receiver_for_type(
315    val: TransferrableInterface,
316) -> fn(&GlobalScope, &mut StructuredDataReader<'_>, u64, RawMutableHandleObject) -> Result<(), ()>
317{
318    match val {
319        TransferrableInterface::ImageBitmap => receive_object::<ImageBitmap>,
320        TransferrableInterface::MessagePort => receive_object::<MessagePort>,
321        TransferrableInterface::OffscreenCanvas => receive_object::<OffscreenCanvas>,
322        TransferrableInterface::ReadableStream => receive_object::<ReadableStream>,
323        TransferrableInterface::WritableStream => receive_object::<WritableStream>,
324        TransferrableInterface::TransformStream => receive_object::<TransformStream>,
325    }
326}
327
328fn receive_object<T: Transferable>(
329    owner: &GlobalScope,
330    sc_reader: &mut StructuredDataReader<'_>,
331    extra_data: u64,
332    return_object: RawMutableHandleObject,
333) -> Result<(), ()> {
334    // 1. Re-build the key for the storage location
335    // of the transferred object.
336    let big: [u8; 8] = extra_data.to_ne_bytes();
337    let (name_space, index) = big.split_at(4);
338
339    let namespace_id = PipelineNamespaceId(u32::from_ne_bytes(
340        name_space
341            .try_into()
342            .expect("name_space to be a slice of four."),
343    ));
344    let id: NamespaceIndex<T::Index> = NamespaceIndex {
345        namespace_id,
346        index: Index::new(u32::from_ne_bytes(
347            index.try_into().expect("index to be a slice of four."),
348        ))
349        .expect("Index to be non-zero"),
350    };
351
352    // 2. Get the transferred object from its storage, using the key.
353    let storage = T::serialized_storage(StructuredData::Reader(sc_reader));
354    let serialized = if let Some(objects) = storage.as_mut() {
355        let object = objects.remove(&id).expect("Transferred port to be stored");
356        if objects.is_empty() {
357            *storage = None;
358        }
359        object
360    } else {
361        panic!(
362            "An interface was transfer-received, yet the SC holder does not have any serialized objects"
363        );
364    };
365
366    let Ok(received) = T::transfer_receive(owner, id, serialized) else {
367        return Err(());
368    };
369    return_object.set(received.reflector().rootable().get());
370    sc_reader.roots.push(Heap::boxed(return_object.get()));
371    Ok(())
372}
373
374unsafe extern "C" fn read_transfer_callback(
375    cx: *mut JSContext,
376    _r: *mut JSStructuredCloneReader,
377    _policy: *const CloneDataPolicy,
378    tag: u32,
379    _content: *mut raw::c_void,
380    extra_data: u64,
381    closure: *mut raw::c_void,
382    return_object: RawMutableHandleObject,
383) -> bool {
384    let sc_reader = unsafe { &mut *(closure as *mut StructuredDataReader<'_>) };
385    let in_realm_proof = unsafe { AlreadyInRealm::assert_for_cx(SafeJSContext::from_ptr(cx)) };
386    let owner = unsafe { GlobalScope::from_context(cx, InRealm::Already(&in_realm_proof)) };
387
388    for transferrable in TransferrableInterface::iter() {
389        if tag == StructuredCloneTags::from(transferrable) as u32 {
390            let transfer_receiver = receiver_for_type(transferrable);
391            if transfer_receiver(&owner, sc_reader, extra_data, return_object).is_ok() {
392                return true;
393            }
394        }
395    }
396    false
397}
398
399unsafe fn try_transfer<T: Transferable + IDLInterface>(
400    interface: TransferrableInterface,
401    obj: RawHandleObject,
402    cx: *mut JSContext,
403    sc_writer: &mut StructuredDataWriter,
404    tag: *mut u32,
405    ownership: *mut TransferableOwnership,
406    extra_data: *mut u64,
407) -> Result<(), OperationError> {
408    let object = unsafe { root_from_object::<T>(*obj, cx) };
409    let Ok(object) = object else {
410        return Err(OperationError::InterfaceDoesNotMatch);
411    };
412
413    unsafe { *tag = StructuredCloneTags::from(interface) as u32 };
414    unsafe { *ownership = TransferableOwnership::SCTAG_TMO_CUSTOM };
415
416    let (id, object) = object.transfer().map_err(OperationError::Exception)?;
417
418    // 2. Store the transferred object at a given key.
419    let objects = T::serialized_storage(StructuredData::Writer(sc_writer))
420        .get_or_insert(FxHashMap::default());
421    objects.insert(id, object);
422
423    let index = id.index.0.get();
424
425    let mut big: [u8; 8] = [0; 8];
426    let name_space = id.namespace_id.0.to_ne_bytes();
427    let index = index.to_ne_bytes();
428
429    let (left, right) = big.split_at_mut(4);
430    left.copy_from_slice(&name_space);
431    right.copy_from_slice(&index);
432
433    // 3. Return a u64 representation of the key where the object is stored.
434    unsafe { *extra_data = u64::from_ne_bytes(big) };
435    Ok(())
436}
437
438type TransferOperation = unsafe fn(
439    TransferrableInterface,
440    RawHandleObject,
441    *mut JSContext,
442    &mut StructuredDataWriter,
443    *mut u32,
444    *mut TransferableOwnership,
445    *mut u64,
446) -> Result<(), OperationError>;
447
448fn transfer_for_type(val: TransferrableInterface) -> TransferOperation {
449    match val {
450        TransferrableInterface::ImageBitmap => try_transfer::<ImageBitmap>,
451        TransferrableInterface::MessagePort => try_transfer::<MessagePort>,
452        TransferrableInterface::OffscreenCanvas => try_transfer::<OffscreenCanvas>,
453        TransferrableInterface::ReadableStream => try_transfer::<ReadableStream>,
454        TransferrableInterface::WritableStream => try_transfer::<WritableStream>,
455        TransferrableInterface::TransformStream => try_transfer::<TransformStream>,
456    }
457}
458
459/// <https://html.spec.whatwg.org/multipage/#structuredserializewithtransfer>
460unsafe extern "C" fn write_transfer_callback(
461    cx: *mut JSContext,
462    obj: RawHandleObject,
463    closure: *mut raw::c_void,
464    tag: *mut u32,
465    ownership: *mut TransferableOwnership,
466    _content: *mut *mut raw::c_void,
467    extra_data: *mut u64,
468) -> bool {
469    let sc_writer = unsafe { &mut *(closure as *mut StructuredDataWriter) };
470    for transferable in TransferrableInterface::iter() {
471        let try_transfer = transfer_for_type(transferable);
472
473        let transfer_result =
474            unsafe { try_transfer(transferable, obj, cx, sc_writer, tag, ownership, extra_data) };
475        match transfer_result {
476            Err(error) => match error {
477                OperationError::InterfaceDoesNotMatch => {},
478                OperationError::Exception(error) => {
479                    sc_writer.error = Some(error);
480                    return false;
481                },
482            },
483            Ok(..) => return true,
484        }
485    }
486
487    false
488}
489
490unsafe extern "C" fn free_transfer_callback(
491    _tag: u32,
492    _ownership: TransferableOwnership,
493    _content: *mut raw::c_void,
494    _extra_data: u64,
495    _closure: *mut raw::c_void,
496) {
497}
498
499unsafe fn can_transfer_for_type(
500    transferable: TransferrableInterface,
501    obj: RawHandleObject,
502    cx: *mut JSContext,
503) -> Result<bool, ()> {
504    unsafe fn can_transfer<T: Transferable + IDLInterface>(
505        obj: RawHandleObject,
506        cx: *mut JSContext,
507    ) -> Result<bool, ()> {
508        unsafe { root_from_object::<T>(*obj, cx).map(|o| Transferable::can_transfer(&*o)) }
509    }
510
511    unsafe {
512        match transferable {
513            TransferrableInterface::ImageBitmap => can_transfer::<ImageBitmap>(obj, cx),
514            TransferrableInterface::MessagePort => can_transfer::<MessagePort>(obj, cx),
515            TransferrableInterface::OffscreenCanvas => can_transfer::<OffscreenCanvas>(obj, cx),
516            TransferrableInterface::ReadableStream => can_transfer::<ReadableStream>(obj, cx),
517            TransferrableInterface::WritableStream => can_transfer::<WritableStream>(obj, cx),
518            TransferrableInterface::TransformStream => can_transfer::<TransformStream>(obj, cx),
519        }
520    }
521}
522
523unsafe extern "C" fn can_transfer_callback(
524    cx: *mut JSContext,
525    obj: RawHandleObject,
526    _same_process_scope_required: *mut bool,
527    _closure: *mut raw::c_void,
528) -> bool {
529    for transferable in TransferrableInterface::iter() {
530        let can_transfer = unsafe { can_transfer_for_type(transferable, obj, cx) };
531        if let Ok(can_transfer) = can_transfer {
532            return can_transfer;
533        }
534    }
535    false
536}
537
538unsafe extern "C" fn report_error_callback(
539    _cx: *mut JSContext,
540    _errorid: u32,
541    closure: *mut raw::c_void,
542    error_message: *const ::std::os::raw::c_char,
543) {
544    let msg_result = unsafe { CStr::from_ptr(error_message).to_str().map(str::to_string) };
545
546    if let Ok(msg) = msg_result {
547        let error = unsafe { &mut *(closure as *mut Option<Error>) };
548
549        if error.is_none() {
550            *error = Some(Error::DataClone(Some(msg)));
551        }
552    }
553}
554
555unsafe extern "C" fn sab_cloned_callback(
556    _cx: *mut JSContext,
557    _receiving: bool,
558    _closure: *mut ::std::os::raw::c_void,
559) -> bool {
560    false
561}
562
563static STRUCTURED_CLONE_CALLBACKS: JSStructuredCloneCallbacks = JSStructuredCloneCallbacks {
564    read: Some(read_callback),
565    write: Some(write_callback),
566    reportError: Some(report_error_callback),
567    readTransfer: Some(read_transfer_callback),
568    writeTransfer: Some(write_transfer_callback),
569    freeTransfer: Some(free_transfer_callback),
570    canTransfer: Some(can_transfer_callback),
571    sabCloned: Some(sab_cloned_callback),
572};
573
574pub(crate) enum StructuredData<'a, 'b> {
575    Reader(&'a mut StructuredDataReader<'b>),
576    Writer(&'a mut StructuredDataWriter),
577}
578
579/// Reader and writer structs for results from, and inputs to, structured-data read/write operations.
580/// <https://html.spec.whatwg.org/multipage/#safe-passing-of-structured-data>
581#[repr(C)]
582pub(crate) struct StructuredDataReader<'a> {
583    /// A error record.
584    error: Option<Error>,
585    /// Rooted copies of every deserialized object to ensure they are not garbage collected.
586    roots: RootedVec<'a, Box<Heap<*mut JSObject>>>,
587    /// A map of port implementations,
588    /// used as part of the "transfer-receiving" steps of ports,
589    /// to produce the DOM ports stored in `message_ports` above.
590    pub(crate) port_impls: Option<FxHashMap<MessagePortId, MessagePortImpl>>,
591    /// A map of transform stream implementations,
592    pub(crate) transform_streams_port_impls: Option<FxHashMap<MessagePortId, TransformStreamData>>,
593    /// A map of blob implementations,
594    /// used as part of the "deserialize" steps of blobs,
595    /// to produce the DOM blobs stored in `blobs` above.
596    pub(crate) blob_impls: Option<FxHashMap<BlobId, BlobImpl>>,
597    /// A map of serialized points.
598    pub(crate) points: Option<FxHashMap<DomPointId, DomPoint>>,
599    /// A map of serialized rects.
600    pub(crate) rects: Option<FxHashMap<DomRectId, DomRect>>,
601    /// A map of serialized quads.
602    pub(crate) quads: Option<FxHashMap<DomQuadId, DomQuad>>,
603    /// A map of serialized matrices.
604    pub(crate) matrices: Option<FxHashMap<DomMatrixId, DomMatrix>>,
605    /// A map of serialized exceptions.
606    pub(crate) exceptions: Option<FxHashMap<DomExceptionId, DomException>>,
607    /// A map of serialized quota exceeded errors.
608    pub(crate) quota_exceeded_errors:
609        Option<FxHashMap<QuotaExceededErrorId, SerializableQuotaExceededError>>,
610    // A map of serialized image bitmaps.
611    pub(crate) image_bitmaps: Option<FxHashMap<ImageBitmapId, SerializableImageBitmap>>,
612    /// A map of transferred image bitmaps.
613    pub(crate) transferred_image_bitmaps: Option<FxHashMap<ImageBitmapId, SerializableImageBitmap>>,
614    /// A map of transferred offscreen canvases.
615    pub(crate) offscreen_canvases:
616        Option<FxHashMap<OffscreenCanvasId, TransferableOffscreenCanvas>>,
617}
618
619/// A data holder for transferred and serialized objects.
620#[derive(Default)]
621#[repr(C)]
622pub(crate) struct StructuredDataWriter {
623    /// Error record.
624    pub(crate) error: Option<Error>,
625    /// Transferred ports.
626    pub(crate) ports: Option<FxHashMap<MessagePortId, MessagePortImpl>>,
627    /// Transferred transform streams.
628    pub(crate) transform_streams_port: Option<FxHashMap<MessagePortId, TransformStreamData>>,
629    /// Serialized points.
630    pub(crate) points: Option<FxHashMap<DomPointId, DomPoint>>,
631    /// Serialized rects.
632    pub(crate) rects: Option<FxHashMap<DomRectId, DomRect>>,
633    /// Serialized quads.
634    pub(crate) quads: Option<FxHashMap<DomQuadId, DomQuad>>,
635    /// Serialized matrices.
636    pub(crate) matrices: Option<FxHashMap<DomMatrixId, DomMatrix>>,
637    /// Serialized exceptions.
638    pub(crate) exceptions: Option<FxHashMap<DomExceptionId, DomException>>,
639    /// Serialized quota exceeded errors.
640    pub(crate) quota_exceeded_errors:
641        Option<FxHashMap<QuotaExceededErrorId, SerializableQuotaExceededError>>,
642    /// Serialized blobs.
643    pub(crate) blobs: Option<FxHashMap<BlobId, BlobImpl>>,
644    /// Serialized image bitmaps.
645    pub(crate) image_bitmaps: Option<FxHashMap<ImageBitmapId, SerializableImageBitmap>>,
646    /// Transferred image bitmaps.
647    pub(crate) transferred_image_bitmaps: Option<FxHashMap<ImageBitmapId, SerializableImageBitmap>>,
648    /// Transferred offscreen canvases.
649    pub(crate) offscreen_canvases:
650        Option<FxHashMap<OffscreenCanvasId, TransferableOffscreenCanvas>>,
651}
652
653/// Writes a structured clone. Returns a `DataClone` error if that fails.
654pub(crate) fn write(
655    cx: SafeJSContext,
656    message: HandleValue,
657    transfer: Option<CustomAutoRooterGuard<Vec<*mut JSObject>>>,
658) -> Fallible<StructuredSerializedData> {
659    unsafe {
660        rooted!(in(*cx) let mut val = UndefinedValue());
661        if let Some(transfer) = transfer {
662            transfer.safe_to_jsval(cx, val.handle_mut());
663        }
664        let mut sc_writer = StructuredDataWriter::default();
665        let sc_writer_ptr = &mut sc_writer as *mut _;
666
667        let scbuf = JSAutoStructuredCloneBufferWrapper::new(
668            StructuredCloneScope::DifferentProcess,
669            &STRUCTURED_CLONE_CALLBACKS,
670        );
671        let scdata = &mut ((*scbuf.as_raw_ptr()).data_);
672        let policy = CloneDataPolicy {
673            allowIntraClusterClonableSharedObjects_: false,
674            allowSharedMemoryObjects_: false,
675        };
676        let result = JS_WriteStructuredClone(
677            *cx,
678            message,
679            scdata,
680            StructuredCloneScope::DifferentProcess,
681            &policy,
682            &STRUCTURED_CLONE_CALLBACKS,
683            sc_writer_ptr as *mut raw::c_void,
684            val.handle(),
685        );
686        if !result {
687            let error = if JS_IsExceptionPending(*cx) {
688                Error::JSFailed
689            } else {
690                sc_writer.error.unwrap_or(Error::DataClone(None))
691            };
692
693            return Err(error);
694        }
695
696        let nbytes = GetLengthOfJSStructuredCloneData(scdata);
697        let mut data = Vec::with_capacity(nbytes);
698        CopyJSStructuredCloneData(scdata, data.as_mut_ptr());
699        data.set_len(nbytes);
700
701        let data = StructuredSerializedData {
702            serialized: data,
703            ports: sc_writer.ports.take(),
704            transform_streams: sc_writer.transform_streams_port.take(),
705            points: sc_writer.points.take(),
706            rects: sc_writer.rects.take(),
707            quads: sc_writer.quads.take(),
708            matrices: sc_writer.matrices.take(),
709            exceptions: sc_writer.exceptions.take(),
710            quota_exceeded_errors: sc_writer.quota_exceeded_errors.take(),
711            blobs: sc_writer.blobs.take(),
712            image_bitmaps: sc_writer.image_bitmaps.take(),
713            transferred_image_bitmaps: sc_writer.transferred_image_bitmaps.take(),
714            offscreen_canvases: sc_writer.offscreen_canvases.take(),
715        };
716
717        Ok(data)
718    }
719}
720
721/// Read structured serialized data, possibly containing transferred objects.
722/// Returns a vec of rooted transfer-received ports, or an error.
723pub(crate) fn read(
724    global: &GlobalScope,
725    mut data: StructuredSerializedData,
726    rval: MutableHandleValue,
727) -> Fallible<Vec<DomRoot<MessagePort>>> {
728    let cx = GlobalScope::get_cx();
729    let _ac = enter_realm(global);
730    rooted_vec!(let mut roots);
731    let mut sc_reader = StructuredDataReader {
732        error: None,
733        roots,
734        port_impls: data.ports.take(),
735        transform_streams_port_impls: data.transform_streams.take(),
736        blob_impls: data.blobs.take(),
737        points: data.points.take(),
738        rects: data.rects.take(),
739        quads: data.quads.take(),
740        matrices: data.matrices.take(),
741        exceptions: data.exceptions.take(),
742        quota_exceeded_errors: data.quota_exceeded_errors.take(),
743        image_bitmaps: data.image_bitmaps.take(),
744        transferred_image_bitmaps: data.transferred_image_bitmaps.take(),
745        offscreen_canvases: data.offscreen_canvases.take(),
746    };
747    let sc_reader_ptr = &mut sc_reader as *mut _;
748    unsafe {
749        let scbuf = JSAutoStructuredCloneBufferWrapper::new(
750            StructuredCloneScope::DifferentProcess,
751            &STRUCTURED_CLONE_CALLBACKS,
752        );
753        let scdata = &mut ((*scbuf.as_raw_ptr()).data_);
754
755        WriteBytesToJSStructuredCloneData(
756            data.serialized.as_mut_ptr() as *const u8,
757            data.serialized.len(),
758            scdata,
759        );
760
761        let result = JS_ReadStructuredClone(
762            *cx,
763            scdata,
764            JS_STRUCTURED_CLONE_VERSION,
765            StructuredCloneScope::DifferentProcess,
766            rval,
767            &CloneDataPolicy {
768                allowIntraClusterClonableSharedObjects_: false,
769                allowSharedMemoryObjects_: false,
770            },
771            &STRUCTURED_CLONE_CALLBACKS,
772            sc_reader_ptr as *mut raw::c_void,
773        );
774        if !result {
775            let error = if JS_IsExceptionPending(*cx) {
776                Error::JSFailed
777            } else {
778                sc_reader.error.unwrap_or(Error::DataClone(None))
779            };
780
781            return Err(error);
782        }
783
784        let mut message_ports = vec![];
785        for reflector in sc_reader.roots.iter() {
786            let Ok(message_port) = root_from_object::<MessagePort>(reflector.get(), *cx) else {
787                continue;
788            };
789            message_ports.push(message_port);
790        }
791        // Any transfer-received port-impls should have been taken out.
792        assert!(sc_reader.port_impls.is_none());
793        Ok(message_ports)
794    }
795}
script/dom/bindings/structuredclone.rs

script/dom/bindings/
structuredclone.rs
