Move more bindings code to script_bindings (#35578)

* Move JSContext wrapper to script_bindings.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

* Move webidl constant bindings to script_bindings.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

* Move CanGc to script_bindings.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

* Move Dom<T> and Root<T> types to script_bindings.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

* Formatting.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

* Extra docs for new traits.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

* Fix clippy warnings.

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

---------

Signed-off-by: Josh Matthews <josh@joshmatthews.net>
This commit is contained in:
Josh Matthews 2025-02-21 23:46:56 -05:00 committed by GitHub
parent 54286229ea
commit 35f21e426b
No known key found for this signature in database
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23 changed files with 788 additions and 641 deletions

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@ -0,0 +1,70 @@
/* 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 https://mozilla.org/MPL/2.0/. */
//! WebIDL constants.
use std::ffi::CStr;
use js::jsapi::{JSPROP_ENUMERATE, JSPROP_PERMANENT, JSPROP_READONLY};
use js::jsval::{BooleanValue, DoubleValue, Int32Value, JSVal, NullValue, UInt32Value};
use js::rooted;
use js::rust::wrappers::JS_DefineProperty;
use js::rust::HandleObject;
use crate::script_runtime::JSContext;
/// Representation of an IDL constant.
#[derive(Clone)]
pub struct ConstantSpec {
/// name of the constant.
pub name: &'static CStr,
/// value of the constant.
pub value: ConstantVal,
}
/// Representation of an IDL constant value.
#[derive(Clone)]
#[allow(dead_code)]
pub enum ConstantVal {
/// `long` constant.
Int(i32),
/// `unsigned long` constant.
Uint(u32),
/// `double` constant.
Double(f64),
/// `boolean` constant.
Bool(bool),
/// `null` constant.
Null,
}
impl ConstantSpec {
/// Returns a `JSVal` that represents the value of this `ConstantSpec`.
pub fn get_value(&self) -> JSVal {
match self.value {
ConstantVal::Null => NullValue(),
ConstantVal::Int(i) => Int32Value(i),
ConstantVal::Uint(u) => UInt32Value(u),
ConstantVal::Double(d) => DoubleValue(d),
ConstantVal::Bool(b) => BooleanValue(b),
}
}
}
/// Defines constants on `obj`.
/// Fails on JSAPI failure.
pub fn define_constants(cx: JSContext, obj: HandleObject, constants: &[ConstantSpec]) {
for spec in constants {
rooted!(in(*cx) let value = spec.get_value());
unsafe {
assert!(JS_DefineProperty(
*cx,
obj,
spec.name.as_ptr(),
value.handle(),
(JSPROP_ENUMERATE | JSPROP_READONLY | JSPROP_PERMANENT) as u32
));
}
}
}

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@ -8,18 +8,23 @@ use js::conversions::{
latin1_to_string, ConversionResult, FromJSValConvertible, ToJSValConvertible,
};
use js::error::throw_type_error;
use js::glue::{GetProxyHandlerExtra, IsProxyHandlerFamily};
use js::glue::{
GetProxyHandlerExtra, GetProxyReservedSlot, IsProxyHandlerFamily, IsWrapper,
JS_GetReservedSlot, UnwrapObjectDynamic,
};
use js::jsapi::{
JSContext, JSObject, JSString, JS_DeprecatedStringHasLatin1Chars,
JS_GetLatin1StringCharsAndLength, JS_GetTwoByteStringCharsAndLength, JS_NewStringCopyN,
};
use js::jsval::{ObjectValue, StringValue};
use js::jsval::{ObjectValue, StringValue, UndefinedValue};
use js::rust::{
get_object_class, is_dom_class, maybe_wrap_value, HandleValue, MutableHandleValue, ToString,
get_object_class, is_dom_class, is_dom_object, maybe_wrap_value, HandleValue,
MutableHandleValue, ToString,
};
use crate::inheritance::Castable;
use crate::reflector::Reflector;
use crate::reflector::{DomObject, Reflector};
use crate::root::DomRoot;
use crate::str::{ByteString, DOMString, USVString};
use crate::utils::{DOMClass, DOMJSClass};
@ -199,6 +204,27 @@ impl ToJSValConvertible for Reflector {
}
}
impl<T: DomObject + IDLInterface> FromJSValConvertible for DomRoot<T> {
type Config = ();
unsafe fn from_jsval(
cx: *mut JSContext,
value: HandleValue,
_config: Self::Config,
) -> Result<ConversionResult<DomRoot<T>>, ()> {
Ok(match root_from_handlevalue(value, cx) {
Ok(result) => ConversionResult::Success(result),
Err(()) => ConversionResult::Failure("value is not an object".into()),
})
}
}
impl<T: DomObject> ToJSValConvertible for DomRoot<T> {
unsafe fn to_jsval(&self, cx: *mut JSContext, rval: MutableHandleValue) {
self.reflector().to_jsval(cx, rval);
}
}
/// Get the `DOMClass` from `obj`, or `Err(())` if `obj` is not a DOM object.
///
/// # Safety
@ -230,3 +256,134 @@ pub unsafe fn is_dom_proxy(obj: *mut JSObject) -> bool {
((*clasp).flags & js::JSCLASS_IS_PROXY) != 0 && IsProxyHandlerFamily(obj)
}
}
/// The index of the slot wherein a pointer to the reflected DOM object is
/// stored for non-proxy bindings.
// We use slot 0 for holding the raw object. This is safe for both
// globals and non-globals.
pub const DOM_OBJECT_SLOT: u32 = 0;
/// Get the private pointer of a DOM object from a given reflector.
///
/// # Safety
/// obj must point to a valid non-null JS object.
pub unsafe fn private_from_object(obj: *mut JSObject) -> *const libc::c_void {
let mut value = UndefinedValue();
if is_dom_object(obj) {
JS_GetReservedSlot(obj, DOM_OBJECT_SLOT, &mut value);
} else {
debug_assert!(is_dom_proxy(obj));
GetProxyReservedSlot(obj, 0, &mut value);
};
if value.is_undefined() {
ptr::null()
} else {
value.to_private()
}
}
pub enum PrototypeCheck {
Derive(fn(&'static DOMClass) -> bool),
Depth { depth: usize, proto_id: u16 },
}
/// Get a `*const libc::c_void` for the given DOM object, unwrapping any
/// wrapper around it first, and checking if the object is of the correct type.
///
/// Returns Err(()) if `obj` is an opaque security wrapper or if the object is
/// not an object for a DOM object of the given type (as defined by the
/// proto_id and proto_depth).
///
/// # Safety
/// obj must point to a valid, non-null JS object.
/// cx must point to a valid, non-null JS context.
#[inline]
#[allow(clippy::result_unit_err)]
pub unsafe fn private_from_proto_check(
mut obj: *mut JSObject,
cx: *mut JSContext,
proto_check: PrototypeCheck,
) -> Result<*const libc::c_void, ()> {
let dom_class = get_dom_class(obj).or_else(|_| {
if IsWrapper(obj) {
trace!("found wrapper");
obj = UnwrapObjectDynamic(obj, cx, /* stopAtWindowProxy = */ false);
if obj.is_null() {
trace!("unwrapping security wrapper failed");
Err(())
} else {
assert!(!IsWrapper(obj));
trace!("unwrapped successfully");
get_dom_class(obj)
}
} else {
trace!("not a dom wrapper");
Err(())
}
})?;
let prototype_matches = match proto_check {
PrototypeCheck::Derive(f) => (f)(dom_class),
PrototypeCheck::Depth { depth, proto_id } => {
dom_class.interface_chain[depth] as u16 == proto_id
},
};
if prototype_matches {
trace!("good prototype");
Ok(private_from_object(obj))
} else {
trace!("bad prototype");
Err(())
}
}
/// Get a `*const T` for a DOM object accessible from a `JSObject`.
///
/// # Safety
/// obj must point to a valid, non-null JS object.
/// cx must point to a valid, non-null JS context.
#[allow(clippy::result_unit_err)]
pub unsafe fn native_from_object<T>(obj: *mut JSObject, cx: *mut JSContext) -> Result<*const T, ()>
where
T: DomObject + IDLInterface,
{
unsafe {
private_from_proto_check(obj, cx, PrototypeCheck::Derive(T::derives))
.map(|ptr| ptr as *const T)
}
}
/// Get a `DomRoot<T>` for the given DOM object, unwrapping any wrapper
/// around it first, and checking if the object is of the correct type.
///
/// Returns Err(()) if `obj` is an opaque security wrapper or if the object is
/// not a reflector for a DOM object of the given type (as defined by the
/// proto_id and proto_depth).
///
/// # Safety
/// obj must point to a valid, non-null JS object.
/// cx must point to a valid, non-null JS context.
#[allow(clippy::result_unit_err)]
pub unsafe fn root_from_object<T>(obj: *mut JSObject, cx: *mut JSContext) -> Result<DomRoot<T>, ()>
where
T: DomObject + IDLInterface,
{
native_from_object(obj, cx).map(|ptr| unsafe { DomRoot::from_ref(&*ptr) })
}
/// Get a `DomRoot<T>` for a DOM object accessible from a `HandleValue`.
/// Caller is responsible for throwing a JS exception if needed in case of error.
///
/// # Safety
/// cx must point to a valid, non-null JS context.
#[allow(clippy::result_unit_err)]
pub unsafe fn root_from_handlevalue<T>(v: HandleValue, cx: *mut JSContext) -> Result<DomRoot<T>, ()>
where
T: DomObject + IDLInterface,
{
if !v.get().is_object() {
return Err(());
}
root_from_object(v.get().to_object(), cx)
}

View file

@ -18,12 +18,14 @@ extern crate log;
extern crate malloc_size_of_derive;
pub mod callback;
pub mod constant;
pub mod conversions;
pub mod inheritance;
pub mod reflector;
pub mod root;
pub mod script_runtime;
pub mod str;
mod trace;
pub mod trace;
pub mod utils;
#[allow(non_snake_case)]

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@ -0,0 +1,432 @@
/* 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 https://mozilla.org/MPL/2.0/. */
use std::cell::{Cell, UnsafeCell};
use std::hash::{Hash, Hasher};
use std::ops::Deref;
use std::{fmt, mem, ptr};
use js::gc::Traceable as JSTraceable;
use js::jsapi::{JSObject, JSTracer};
use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
use style::thread_state;
use crate::conversions::DerivedFrom;
use crate::inheritance::Castable;
use crate::reflector::{DomObject, MutDomObject, Reflector};
use crate::trace::trace_reflector;
/// A rooted value.
#[cfg_attr(crown, crown::unrooted_must_root_lint::allow_unrooted_interior)]
pub struct Root<T: StableTraceObject> {
/// The value to root.
value: T,
/// List that ensures correct dynamic root ordering
root_list: *const RootCollection,
}
impl<T> Root<T>
where
T: StableTraceObject + 'static,
{
/// Create a new stack-bounded root for the provided value.
/// It gives out references which cannot outlive this new `Root`.
///
/// # Safety
/// It must not outlive its associated `RootCollection`.
#[cfg_attr(crown, allow(crown::unrooted_must_root))]
pub unsafe fn new(value: T) -> Self {
unsafe fn add_to_root_list(object: *const dyn JSTraceable) -> *const RootCollection {
assert_in_script();
STACK_ROOTS.with(|root_list| {
let root_list = &*root_list.get().unwrap();
root_list.root(object);
root_list
})
}
let root_list = add_to_root_list(value.stable_trace_object());
Root { value, root_list }
}
}
/// `StableTraceObject` represents values that can be rooted through a stable address that will
/// not change for their whole lifetime.
/// It is an unsafe trait that requires implementors to ensure certain safety guarantees.
///
/// # Safety
///
/// Implementors of this trait must ensure that the `trace` method correctly accounts for all
/// owned and referenced objects, so that the garbage collector can accurately determine which
/// objects are still in use. Failing to adhere to this contract may result in undefined behavior,
/// such as use-after-free errors.
pub unsafe trait StableTraceObject {
/// Returns a stable trace object which address won't change for the whole
/// lifetime of the value.
fn stable_trace_object(&self) -> *const dyn JSTraceable;
}
unsafe impl<T> StableTraceObject for Dom<T>
where
T: DomObject,
{
fn stable_trace_object(&self) -> *const dyn JSTraceable {
// The JSTraceable impl for Reflector doesn't actually do anything,
// so we need this shenanigan to actually trace the reflector of the
// T pointer in Dom<T>.
#[cfg_attr(crown, allow(crown::unrooted_must_root))]
struct ReflectorStackRoot(Reflector);
unsafe impl JSTraceable for ReflectorStackRoot {
unsafe fn trace(&self, tracer: *mut JSTracer) {
trace_reflector(tracer, "on stack", &self.0);
}
}
unsafe { &*(self.reflector() as *const Reflector as *const ReflectorStackRoot) }
}
}
unsafe impl<T> StableTraceObject for MaybeUnreflectedDom<T>
where
T: DomObject,
{
fn stable_trace_object(&self) -> *const dyn JSTraceable {
// The JSTraceable impl for Reflector doesn't actually do anything,
// so we need this shenanigan to actually trace the reflector of the
// T pointer in Dom<T>.
#[cfg_attr(crown, allow(crown::unrooted_must_root))]
struct MaybeUnreflectedStackRoot<T>(T);
unsafe impl<T> JSTraceable for MaybeUnreflectedStackRoot<T>
where
T: DomObject,
{
unsafe fn trace(&self, tracer: *mut JSTracer) {
if self.0.reflector().get_jsobject().is_null() {
self.0.trace(tracer);
} else {
trace_reflector(tracer, "on stack", self.0.reflector());
}
}
}
unsafe { &*(self.ptr.as_ptr() as *const T as *const MaybeUnreflectedStackRoot<T>) }
}
}
impl<T> Deref for Root<T>
where
T: Deref + StableTraceObject,
{
type Target = <T as Deref>::Target;
fn deref(&self) -> &Self::Target {
assert_in_script();
&self.value
}
}
impl<T> Drop for Root<T>
where
T: StableTraceObject,
{
fn drop(&mut self) {
unsafe {
(*self.root_list).unroot(self.value.stable_trace_object());
}
}
}
impl<T: fmt::Debug + StableTraceObject> fmt::Debug for Root<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.value.fmt(f)
}
}
impl<T: fmt::Debug + DomObject> fmt::Debug for Dom<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
(**self).fmt(f)
}
}
/// A traced reference to a DOM object
///
/// This type is critical to making garbage collection work with the DOM,
/// but it is very dangerous; if garbage collection happens with a `Dom<T>`
/// on the stack, the `Dom<T>` can point to freed memory.
///
/// This should only be used as a field in other DOM objects.
#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
#[repr(transparent)]
pub struct Dom<T> {
ptr: ptr::NonNull<T>,
}
// Dom<T> is similar to Rc<T>, in that it's not always clear how to avoid double-counting.
// For now, we choose not to follow any such pointers.
impl<T> MallocSizeOf for Dom<T> {
fn size_of(&self, _ops: &mut MallocSizeOfOps) -> usize {
0
}
}
impl<T> PartialEq for Dom<T> {
fn eq(&self, other: &Dom<T>) -> bool {
self.ptr.as_ptr() == other.ptr.as_ptr()
}
}
impl<'a, T: DomObject> PartialEq<&'a T> for Dom<T> {
fn eq(&self, other: &&'a T) -> bool {
*self == Dom::from_ref(*other)
}
}
impl<T> Eq for Dom<T> {}
impl<T> Hash for Dom<T> {
fn hash<H: Hasher>(&self, state: &mut H) {
self.ptr.as_ptr().hash(state)
}
}
impl<T> Clone for Dom<T> {
#[inline]
#[cfg_attr(crown, allow(crown::unrooted_must_root))]
fn clone(&self) -> Self {
assert_in_script();
Dom { ptr: self.ptr }
}
}
impl<T: DomObject> Dom<T> {
/// Create a `Dom<T>` from a `&T`
#[cfg_attr(crown, allow(crown::unrooted_must_root))]
pub fn from_ref(obj: &T) -> Dom<T> {
assert_in_script();
Dom {
ptr: ptr::NonNull::from(obj),
}
}
/// Return a rooted version of this DOM object ([`DomRoot<T>`]) suitable for use on the stack.
pub fn as_rooted(&self) -> DomRoot<T> {
DomRoot::from_ref(self)
}
pub fn as_ptr(&self) -> *const T {
self.ptr.as_ptr()
}
}
impl<T: DomObject> Deref for Dom<T> {
type Target = T;
fn deref(&self) -> &T {
assert_in_script();
// We can only have &Dom<T> from a rooted thing, so it's safe to deref
// it to &T.
unsafe { &*self.ptr.as_ptr() }
}
}
unsafe impl<T: DomObject> JSTraceable for Dom<T> {
unsafe fn trace(&self, trc: *mut JSTracer) {
let trace_string;
let trace_info = if cfg!(debug_assertions) {
trace_string = format!("for {} on heap", ::std::any::type_name::<T>());
&trace_string[..]
} else {
"for DOM object on heap"
};
trace_reflector(trc, trace_info, (*self.ptr.as_ptr()).reflector());
}
}
/// A traced reference to a DOM object that may not be reflected yet.
#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
pub struct MaybeUnreflectedDom<T> {
ptr: ptr::NonNull<T>,
}
impl<T> MaybeUnreflectedDom<T>
where
T: DomObject,
{
/// Create a new MaybeUnreflectedDom value from the given boxed DOM object.
///
/// # Safety
/// TODO: unclear why this is marked unsafe.
#[cfg_attr(crown, allow(crown::unrooted_must_root))]
pub unsafe fn from_box(value: Box<T>) -> Self {
Self {
ptr: Box::leak(value).into(),
}
}
}
impl<T> Root<MaybeUnreflectedDom<T>>
where
T: DomObject,
{
pub fn as_ptr(&self) -> *const T {
self.value.ptr.as_ptr()
}
}
impl<T> Root<MaybeUnreflectedDom<T>>
where
T: MutDomObject,
{
/// Treat the given JS object as the reflector of this unreflected object.
///
/// # Safety
/// obj must point to a valid, non-null JS object.
pub unsafe fn reflect_with(self, obj: *mut JSObject) -> DomRoot<T> {
let ptr = self.as_ptr();
drop(self);
let root = DomRoot::from_ref(&*ptr);
root.init_reflector(obj);
root
}
}
/// A rooted reference to a DOM object.
pub type DomRoot<T> = Root<Dom<T>>;
impl<T: Castable> DomRoot<T> {
/// Cast a DOM object root upwards to one of the interfaces it derives from.
pub fn upcast<U>(root: DomRoot<T>) -> DomRoot<U>
where
U: Castable,
T: DerivedFrom<U>,
{
unsafe { mem::transmute::<DomRoot<T>, DomRoot<U>>(root) }
}
/// Cast a DOM object root downwards to one of the interfaces it might implement.
pub fn downcast<U>(root: DomRoot<T>) -> Option<DomRoot<U>>
where
U: DerivedFrom<T>,
{
if root.is::<U>() {
Some(unsafe { mem::transmute::<DomRoot<T>, DomRoot<U>>(root) })
} else {
None
}
}
}
impl<T: DomObject> DomRoot<T> {
/// Generate a new root from a reference
pub fn from_ref(unrooted: &T) -> DomRoot<T> {
unsafe { DomRoot::new(Dom::from_ref(unrooted)) }
}
/// Create a traced version of this rooted object.
///
/// # Safety
///
/// This should never be used to create on-stack values. Instead these values should always
/// end up as members of other DOM objects.
#[cfg_attr(crown, allow(crown::unrooted_must_root))]
pub fn as_traced(&self) -> Dom<T> {
Dom::from_ref(self)
}
}
impl<T> MallocSizeOf for DomRoot<T>
where
T: DomObject + MallocSizeOf,
{
fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize {
(**self).size_of(ops)
}
}
impl<T> PartialEq for DomRoot<T>
where
T: DomObject,
{
fn eq(&self, other: &Self) -> bool {
self.value == other.value
}
}
impl<T> Clone for DomRoot<T>
where
T: DomObject,
{
fn clone(&self) -> DomRoot<T> {
DomRoot::from_ref(self)
}
}
unsafe impl<T> JSTraceable for DomRoot<T>
where
T: DomObject,
{
unsafe fn trace(&self, _: *mut JSTracer) {
// Already traced.
}
}
/// A rooting mechanism for reflectors on the stack.
/// LIFO is not required.
///
/// See also [*Exact Stack Rooting - Storing a GCPointer on the CStack*][cstack].
///
/// [cstack]: https://developer.mozilla.org/en-US/docs/Mozilla/Projects/SpiderMonkey/Internals/GC/Exact_Stack_Rooting
pub struct RootCollection {
roots: UnsafeCell<Vec<*const dyn JSTraceable>>,
}
impl RootCollection {
/// Create an empty collection of roots
#[allow(clippy::new_without_default)]
pub fn new() -> RootCollection {
assert_in_script();
RootCollection {
roots: UnsafeCell::new(vec![]),
}
}
/// Starts tracking a trace object.
unsafe fn root(&self, object: *const dyn JSTraceable) {
assert_in_script();
(*self.roots.get()).push(object);
}
/// Stops tracking a trace object, asserting if it isn't found.
unsafe fn unroot(&self, object: *const dyn JSTraceable) {
assert_in_script();
let roots = &mut *self.roots.get();
match roots
.iter()
.rposition(|r| std::ptr::addr_eq(*r as *const (), object as *const ()))
{
Some(idx) => {
roots.remove(idx);
},
None => panic!("Can't remove a root that was never rooted!"),
}
}
}
thread_local!(pub static STACK_ROOTS: Cell<Option<*const RootCollection>> = const { Cell::new(None) });
/// SM Callback that traces the rooted reflectors
///
/// # Safety
/// tracer must point to a valid, non-null JS tracer object.
pub unsafe fn trace_roots(tracer: *mut JSTracer) {
trace!("tracing stack roots");
STACK_ROOTS.with(|collection| {
let collection = &*(*collection.get().unwrap()).roots.get();
for root in collection {
(**root).trace(tracer);
}
});
}
pub fn assert_in_script() {
debug_assert!(thread_state::get().is_script());
}

View file

@ -3,6 +3,35 @@
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
use std::cell::Cell;
use std::marker::PhantomData;
use std::ops::Deref;
use js::jsapi::JSContext as RawJSContext;
#[derive(Clone, Copy)]
#[repr(transparent)]
pub struct JSContext(*mut RawJSContext);
#[allow(unsafe_code)]
impl JSContext {
/// Create a new [`JSContext`] object from the given raw pointer.
///
/// # Safety
///
/// The `RawJSContext` argument must point to a valid `RawJSContext` in memory.
pub unsafe fn from_ptr(raw_js_context: *mut RawJSContext) -> Self {
JSContext(raw_js_context)
}
}
#[allow(unsafe_code)]
impl Deref for JSContext {
type Target = *mut RawJSContext;
fn deref(&self) -> &Self::Target {
&self.0
}
}
thread_local!(
static THREAD_ACTIVE: Cell<bool> = const { Cell::new(true) };
@ -15,3 +44,19 @@ pub fn runtime_is_alive() -> bool {
pub fn mark_runtime_dead() {
THREAD_ACTIVE.with(|t| t.set(false));
}
#[derive(Clone, Copy, Debug)]
/// A compile-time marker that there are operations that could trigger a JS garbage collection
/// operation within the current stack frame. It is trivially copyable, so it should be passed
/// as a function argument and reused when calling other functions whenever possible. Since it
/// is only meaningful within the current stack frame, it is impossible to move it to a different
/// thread or into a task that will execute asynchronously.
pub struct CanGc(PhantomData<*mut ()>);
impl CanGc {
/// Create a new CanGc value, representing that a GC operation is possible within the
/// current stack frame.
pub fn note() -> CanGc {
CanGc(PhantomData)
}
}

View file

@ -2,8 +2,37 @@
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
use js::glue::CallObjectTracer;
use js::jsapi::{GCTraceKindToAscii, Heap, JSObject, JSTracer, TraceKind};
use crate::reflector::Reflector;
use crate::str::{DOMString, USVString};
/// Trace the `JSObject` held by `reflector`.
///
/// # Safety
/// tracer must point to a valid, non-null JS tracer.
#[cfg_attr(crown, allow(crown::unrooted_must_root))]
pub unsafe fn trace_reflector(tracer: *mut JSTracer, description: &str, reflector: &Reflector) {
trace!("tracing reflector {}", description);
trace_object(tracer, description, reflector.rootable())
}
/// Trace a `JSObject`.
///
/// # Safety
/// tracer must point to a valid, non-null JS tracer.
pub unsafe fn trace_object(tracer: *mut JSTracer, description: &str, obj: &Heap<*mut JSObject>) {
unsafe {
trace!("tracing {}", description);
CallObjectTracer(
tracer,
obj.ptr.get() as *mut _,
GCTraceKindToAscii(TraceKind::Object),
);
}
}
/// For use on non-jsmanaged types
/// Use #[derive(JSTraceable)] on JS managed types
macro_rules! unsafe_no_jsmanaged_fields(