Script: implement ReadableStreamBYOBReader::Read (#35040)

* Script: implement ReadableStreamBYOBReader::Read

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

* fix ReadRequest::close_steps

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

* fix clippy

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

* implement viewed_buffer_array_byte_length and byte_length

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

* fix clippy

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

* Correct BufferSource implemntation

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

* Correct detach_buffer implemantation

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

* fix JS_IsArrayBufferViewObject usage

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

* Reduce BufferSource to two variants ArrayBuffer and ArrayBufferView

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

* Add more doc and use promise.reject_error

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

---------

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

components/script/dom/bindings/buffer_source.rs

@@ -11,7 +11,9 @@ use std::ptr;
 use std::sync::Arc;
 
 use js::jsapi::{
-    Heap, JSObject, JS_GetArrayBufferViewBuffer, JS_IsArrayBufferViewObject, NewExternalArrayBuffer,
+    GetArrayBufferByteLength, Heap, IsDetachedArrayBufferObject, JSObject,
+    JS_GetArrayBufferViewBuffer, JS_GetArrayBufferViewByteLength, JS_IsArrayBufferViewObject,
+    JS_IsTypedArrayObject, NewExternalArrayBuffer,
 };
 use js::rust::wrappers::DetachArrayBuffer;
 use js::rust::{CustomAutoRooterGuard, Handle, MutableHandleObject};
@@ -23,54 +25,26 @@ use js::typedarray::{
 use crate::dom::globalscope::GlobalScope;
 use crate::script_runtime::JSContext;
 
-/// <https://webidl.spec.whatwg.org/#BufferSource>
-#[allow(dead_code)]
+// Represents a `BufferSource` as defined in the WebIDL specification.
+///
+/// A `BufferSource` is either an `ArrayBuffer` or an `ArrayBufferView`, which
+/// provides a view onto an `ArrayBuffer`.
+///
+/// See: <https://webidl.spec.whatwg.org/#BufferSource>
 pub(crate) enum BufferSource {
-    Int8Array(Box<Heap<*mut JSObject>>),
-    Int16Array(Box<Heap<*mut JSObject>>),
-    Int32Array(Box<Heap<*mut JSObject>>),
-    Uint8Array(Box<Heap<*mut JSObject>>),
-    Uint16Array(Box<Heap<*mut JSObject>>),
-    Uint32Array(Box<Heap<*mut JSObject>>),
-    Uint8ClampedArray(Box<Heap<*mut JSObject>>),
-    BigInt64Array(Box<Heap<*mut JSObject>>),
-    BigUint64Array(Box<Heap<*mut JSObject>>),
-    Float32Array(Box<Heap<*mut JSObject>>),
-    Float64Array(Box<Heap<*mut JSObject>>),
-    DataView(Box<Heap<*mut JSObject>>),
+    /// Represents an `ArrayBufferView` (e.g., `Uint8Array`, `DataView`).
+    /// See: <https://webidl.spec.whatwg.org/#ArrayBufferView>
+    ArrayBufferView(Box<Heap<*mut JSObject>>),
+
+    /// Represents an `ArrayBuffer`, a fixed-length binary data buffer.
+    /// See: <https://webidl.spec.whatwg.org/#idl-ArrayBuffer>
+    #[allow(dead_code)]
     ArrayBuffer(Box<Heap<*mut JSObject>>),
+
+    /// Default variant, used as a placeholder in initialization.
     Default(Box<Heap<*mut JSObject>>),
 }
 
-pub(crate) struct HeapBufferSource<T> {
-    buffer_source: BufferSource,
-    phantom: PhantomData<T>,
-}
-
-unsafe impl<T> crate::dom::bindings::trace::JSTraceable for HeapBufferSource<T> {
-    #[inline]
-    unsafe fn trace(&self, tracer: *mut js::jsapi::JSTracer) {
-        match &self.buffer_source {
-            BufferSource::Int8Array(buffer) |
-            BufferSource::Int16Array(buffer) |
-            BufferSource::Int32Array(buffer) |
-            BufferSource::Uint8Array(buffer) |
-            BufferSource::Uint16Array(buffer) |
-            BufferSource::Uint32Array(buffer) |
-            BufferSource::Uint8ClampedArray(buffer) |
-            BufferSource::BigInt64Array(buffer) |
-            BufferSource::BigUint64Array(buffer) |
-            BufferSource::Float32Array(buffer) |
-            BufferSource::Float64Array(buffer) |
-            BufferSource::DataView(buffer) |
-            BufferSource::ArrayBuffer(buffer) |
-            BufferSource::Default(buffer) => {
-                buffer.trace(tracer);
-            },
-        }
-    }
-}
-
 pub(crate) fn new_initialized_heap_buffer_source<T>(
     init: HeapTypedArrayInit,
 ) -> Result<HeapBufferSource<T>, ()>
@@ -93,18 +67,7 @@ where
             let heap_buffer_source = HeapBufferSource::<T>::default();
 
             match &heap_buffer_source.buffer_source {
-                BufferSource::Int8Array(buffer) |
-                BufferSource::Int16Array(buffer) |
-                BufferSource::Int32Array(buffer) |
-                BufferSource::Uint8Array(buffer) |
-                BufferSource::Uint16Array(buffer) |
-                BufferSource::Uint32Array(buffer) |
-                BufferSource::Uint8ClampedArray(buffer) |
-                BufferSource::BigInt64Array(buffer) |
-                BufferSource::BigUint64Array(buffer) |
-                BufferSource::Float32Array(buffer) |
-                BufferSource::Float64Array(buffer) |
-                BufferSource::DataView(buffer) |
+                BufferSource::ArrayBufferView(buffer) |
                 BufferSource::ArrayBuffer(buffer) |
                 BufferSource::Default(buffer) => {
                     buffer.set(*array);
@@ -121,11 +84,22 @@ pub(crate) enum HeapTypedArrayInit {
     Info { len: u32, cx: JSContext },
 }
 
+pub(crate) struct HeapBufferSource<T> {
+    buffer_source: BufferSource,
+    phantom: PhantomData<T>,
+}
+
 impl<T> HeapBufferSource<T>
 where
-    T: TypedArrayElement + TypedArrayElementCreator,
-    T::Element: Clone + Copy,
+    T: TypedArrayElement,
 {
+    pub(crate) fn new(buffer_source: BufferSource) -> HeapBufferSource<T> {
+        HeapBufferSource {
+            buffer_source,
+            phantom: PhantomData,
+        }
+    }
+
     pub(crate) fn default() -> HeapBufferSource<T> {
         HeapBufferSource {
             buffer_source: BufferSource::Default(Box::default()),
@@ -133,47 +107,128 @@ where
         }
     }
 
-    pub(crate) fn set_data(&self, cx: JSContext, data: &[T::Element]) -> Result<(), ()> {
-        rooted!(in (*cx) let mut array = ptr::null_mut::<JSObject>());
-        let _: TypedArray<T, *mut JSObject> = create_buffer_source(cx, data, array.handle_mut())?;
-
+    pub(crate) fn is_initialized(&self) -> bool {
         match &self.buffer_source {
-            BufferSource::Int8Array(buffer) |
-            BufferSource::Int16Array(buffer) |
-            BufferSource::Int32Array(buffer) |
-            BufferSource::Uint8Array(buffer) |
-            BufferSource::Uint16Array(buffer) |
-            BufferSource::Uint32Array(buffer) |
-            BufferSource::Uint8ClampedArray(buffer) |
-            BufferSource::BigInt64Array(buffer) |
-            BufferSource::BigUint64Array(buffer) |
-            BufferSource::Float32Array(buffer) |
-            BufferSource::Float64Array(buffer) |
-            BufferSource::DataView(buffer) |
+            BufferSource::ArrayBufferView(buffer) |
             BufferSource::ArrayBuffer(buffer) |
-            BufferSource::Default(buffer) => {
-                buffer.set(*array);
-            },
+            BufferSource::Default(buffer) => !buffer.get().is_null(),
         }
-        Ok(())
     }
 
+    pub(crate) fn get_buffer(&self) -> Result<TypedArray<T, *mut JSObject>, ()> {
+        TypedArray::from(match &self.buffer_source {
+            BufferSource::ArrayBufferView(buffer) |
+            BufferSource::ArrayBuffer(buffer) |
+            BufferSource::Default(buffer) => buffer.get(),
+        })
+    }
+
+    /// <https://tc39.es/ecma262/#sec-detacharraybuffer>
+    pub(crate) fn detach_buffer(&self, cx: JSContext) -> bool {
+        assert!(self.is_initialized());
+        match &self.buffer_source {
+            BufferSource::ArrayBufferView(buffer) | BufferSource::Default(buffer) => {
+                let mut is_shared = false;
+                unsafe {
+                    // assert buffer is an ArrayBuffer view
+                    assert!(JS_IsArrayBufferViewObject(*buffer.handle()));
+                    rooted!(in (*cx) let view_buffer =
+                            JS_GetArrayBufferViewBuffer(*cx, buffer.handle(), &mut is_shared));
+                    // This buffer is always created unshared
+                    debug_assert!(!is_shared);
+                    // Detach the ArrayBuffer
+                    DetachArrayBuffer(*cx, view_buffer.handle())
+                }
+            },
+            BufferSource::ArrayBuffer(buffer) => unsafe {
+                DetachArrayBuffer(*cx, Handle::from_raw(buffer.handle()))
+            },
+        }
+    }
+
+    pub(crate) fn buffer_to_option(&self) -> Option<TypedArray<T, *mut JSObject>> {
+        if self.is_initialized() {
+            self.get_buffer().ok()
+        } else {
+            warn!("Buffer not initialized.");
+            None
+        }
+    }
+
+    pub(crate) fn is_detached_buffer(&self, cx: JSContext) -> bool {
+        assert!(self.is_initialized());
+        match &self.buffer_source {
+            BufferSource::ArrayBufferView(buffer) | BufferSource::Default(buffer) => {
+                let mut is_shared = false;
+                unsafe {
+                    assert!(JS_IsArrayBufferViewObject(*buffer.handle()));
+                    rooted!(in (*cx) let view_buffer =
+                            JS_GetArrayBufferViewBuffer(*cx, buffer.handle(), &mut is_shared));
+                    debug_assert!(!is_shared);
+                    IsDetachedArrayBufferObject(*view_buffer.handle())
+                }
+            },
+            BufferSource::ArrayBuffer(buffer) => unsafe {
+                IsDetachedArrayBufferObject(*buffer.handle())
+            },
+        }
+    }
+
+    pub(crate) fn viewed_buffer_array_byte_length(&self, cx: JSContext) -> usize {
+        assert!(self.is_initialized());
+        match &self.buffer_source {
+            BufferSource::ArrayBufferView(buffer) | BufferSource::Default(buffer) => {
+                let mut is_shared = false;
+                unsafe {
+                    assert!(JS_IsArrayBufferViewObject(*buffer.handle()));
+                    rooted!(in (*cx) let view_buffer =
+                            JS_GetArrayBufferViewBuffer(*cx, buffer.handle(), &mut is_shared));
+                    debug_assert!(!is_shared);
+                    GetArrayBufferByteLength(*view_buffer.handle())
+                }
+            },
+            BufferSource::ArrayBuffer(buffer) => unsafe {
+                GetArrayBufferByteLength(*buffer.handle())
+            },
+        }
+    }
+
+    pub(crate) fn byte_length(&self) -> usize {
+        match &self.buffer_source {
+            BufferSource::ArrayBufferView(buffer) | BufferSource::Default(buffer) => unsafe {
+                JS_GetArrayBufferViewByteLength(*buffer.handle())
+            },
+            BufferSource::ArrayBuffer(buffer) => unsafe {
+                GetArrayBufferByteLength(*buffer.handle())
+            },
+        }
+    }
+
+    pub(crate) fn array_length(&self) -> usize {
+        self.get_buffer().unwrap().len()
+    }
+
+    /// <https://tc39.es/ecma262/#typedarray>
+    pub(crate) fn has_typed_array_name(&self) -> bool {
+        match &self.buffer_source {
+            BufferSource::ArrayBufferView(buffer) | BufferSource::Default(buffer) => unsafe {
+                JS_IsTypedArrayObject(*buffer.handle())
+            },
+            BufferSource::ArrayBuffer(_) => false,
+        }
+    }
+}
+
+impl<T> HeapBufferSource<T>
+where
+    T: TypedArrayElement + TypedArrayElementCreator,
+    T::Element: Clone + Copy,
+{
     pub(crate) fn acquire_data(&self, cx: JSContext) -> Result<Vec<T::Element>, ()> {
         assert!(self.is_initialized());
 
         typedarray!(in(*cx) let array: TypedArray = match &self.buffer_source {
-            BufferSource::Int8Array(buffer) |
-            BufferSource::Int16Array(buffer) |
-            BufferSource::Int32Array(buffer) |
-            BufferSource::Uint8Array(buffer) |
-            BufferSource::Uint16Array(buffer) |
-            BufferSource::Uint32Array(buffer) |
-            BufferSource::Uint8ClampedArray(buffer) |
-            BufferSource::BigInt64Array(buffer) |
-            BufferSource::BigUint64Array(buffer) |
-            BufferSource::Float32Array(buffer) |
-            BufferSource::Float64Array(buffer) |
-            BufferSource::DataView(buffer) |
+            BufferSource::ArrayBufferView(buffer) |
             BufferSource::ArrayBuffer(buffer) |
             BufferSource::Default(buffer) => {
                 buffer.get()
@@ -190,18 +245,7 @@ where
         };
 
         match &self.buffer_source {
-            BufferSource::Int8Array(buffer) |
-            BufferSource::Int16Array(buffer) |
-            BufferSource::Int32Array(buffer) |
-            BufferSource::Uint8Array(buffer) |
-            BufferSource::Uint16Array(buffer) |
-            BufferSource::Uint32Array(buffer) |
-            BufferSource::Uint8ClampedArray(buffer) |
-            BufferSource::BigInt64Array(buffer) |
-            BufferSource::BigUint64Array(buffer) |
-            BufferSource::Float32Array(buffer) |
-            BufferSource::Float64Array(buffer) |
-            BufferSource::DataView(buffer) |
+            BufferSource::ArrayBufferView(buffer) |
             BufferSource::ArrayBuffer(buffer) |
             BufferSource::Default(buffer) => {
                 buffer.set(ptr::null_mut());
@@ -210,43 +254,6 @@ where
         data
     }
 
-    /// <https://tc39.es/ecma262/#sec-detacharraybuffer>
-    pub(crate) fn detach_buffer(&self, cx: JSContext) -> bool {
-        match &self.buffer_source {
-            BufferSource::Int8Array(buffer) |
-            BufferSource::Int16Array(buffer) |
-            BufferSource::Int32Array(buffer) |
-            BufferSource::Uint8Array(buffer) |
-            BufferSource::Uint16Array(buffer) |
-            BufferSource::Uint32Array(buffer) |
-            BufferSource::Uint8ClampedArray(buffer) |
-            BufferSource::BigInt64Array(buffer) |
-            BufferSource::BigUint64Array(buffer) |
-            BufferSource::Float32Array(buffer) |
-            BufferSource::Float64Array(buffer) |
-            BufferSource::DataView(buffer) |
-            BufferSource::ArrayBuffer(buffer) |
-            BufferSource::Default(buffer) => {
-                assert!(self.is_initialized());
-                let mut is_shared = false;
-                unsafe {
-                    if JS_IsArrayBufferViewObject(*buffer.handle()) {
-                        // If it is an ArrayBuffer view, get the buffer using JS_GetArrayBufferViewBuffer
-                        rooted!(in (*cx) let view_buffer =
-                            JS_GetArrayBufferViewBuffer(*cx, buffer.handle(), &mut is_shared));
-                        // This buffer is always created unshared
-                        debug_assert!(!is_shared);
-                        // Detach the ArrayBuffer
-                        DetachArrayBuffer(*cx, view_buffer.handle())
-                    } else {
-                        // If it's not an ArrayBuffer view, Detach the buffer directly
-                        DetachArrayBuffer(*cx, Handle::from_raw(buffer.handle()))
-                    }
-                }
-            },
-        }
-    }
-
     pub(crate) fn copy_data_to(
         &self,
         cx: JSContext,
@@ -256,18 +263,7 @@ where
     ) -> Result<(), ()> {
         assert!(self.is_initialized());
         typedarray!(in(*cx) let array: TypedArray = match &self.buffer_source {
-            BufferSource::Int8Array(buffer) |
-            BufferSource::Int16Array(buffer) |
-            BufferSource::Int32Array(buffer) |
-            BufferSource::Uint8Array(buffer) |
-            BufferSource::Uint16Array(buffer) |
-            BufferSource::Uint32Array(buffer) |
-            BufferSource::Uint8ClampedArray(buffer) |
-            BufferSource::BigInt64Array(buffer) |
-            BufferSource::BigUint64Array(buffer) |
-            BufferSource::Float32Array(buffer) |
-            BufferSource::Float64Array(buffer) |
-            BufferSource::DataView(buffer) |
+            BufferSource::ArrayBufferView(buffer) |
             BufferSource::ArrayBuffer(buffer) |
             BufferSource::Default(buffer) => {
                 buffer.get()
@@ -294,18 +290,7 @@ where
     ) -> Result<(), ()> {
         assert!(self.is_initialized());
         typedarray!(in(*cx) let mut array: TypedArray = match &self.buffer_source {
-            BufferSource::Int8Array(buffer) |
-            BufferSource::Int16Array(buffer) |
-            BufferSource::Int32Array(buffer) |
-            BufferSource::Uint8Array(buffer) |
-            BufferSource::Uint16Array(buffer) |
-            BufferSource::Uint32Array(buffer) |
-            BufferSource::Uint8ClampedArray(buffer) |
-            BufferSource::BigInt64Array(buffer) |
-            BufferSource::BigUint64Array(buffer) |
-            BufferSource::Float32Array(buffer) |
-            BufferSource::Float64Array(buffer) |
-            BufferSource::DataView(buffer) |
+            BufferSource::ArrayBufferView(buffer) |
             BufferSource::ArrayBuffer(buffer) |
             BufferSource::Default(buffer) => {
                 buffer.get()
@@ -324,50 +309,30 @@ where
         Ok(())
     }
 
-    pub(crate) fn is_initialized(&self) -> bool {
+    pub(crate) fn set_data(&self, cx: JSContext, data: &[T::Element]) -> Result<(), ()> {
+        rooted!(in (*cx) let mut array = ptr::null_mut::<JSObject>());
+        let _: TypedArray<T, *mut JSObject> = create_buffer_source(cx, data, array.handle_mut())?;
+
         match &self.buffer_source {
-            BufferSource::Int8Array(buffer) |
-            BufferSource::Int16Array(buffer) |
-            BufferSource::Int32Array(buffer) |
-            BufferSource::Uint8Array(buffer) |
-            BufferSource::Uint16Array(buffer) |
-            BufferSource::Uint32Array(buffer) |
-            BufferSource::Uint8ClampedArray(buffer) |
-            BufferSource::BigInt64Array(buffer) |
-            BufferSource::BigUint64Array(buffer) |
-            BufferSource::Float32Array(buffer) |
-            BufferSource::Float64Array(buffer) |
-            BufferSource::DataView(buffer) |
+            BufferSource::ArrayBufferView(buffer) |
             BufferSource::ArrayBuffer(buffer) |
-            BufferSource::Default(buffer) => !buffer.get().is_null(),
+            BufferSource::Default(buffer) => {
+                buffer.set(*array);
+            },
         }
+        Ok(())
     }
+}
 
-    pub(crate) fn get_buffer(&self) -> Result<TypedArray<T, *mut JSObject>, ()> {
-        TypedArray::from(match &self.buffer_source {
-            BufferSource::Int8Array(buffer) |
-            BufferSource::Int16Array(buffer) |
-            BufferSource::Int32Array(buffer) |
-            BufferSource::Uint8Array(buffer) |
-            BufferSource::Uint16Array(buffer) |
-            BufferSource::Uint32Array(buffer) |
-            BufferSource::Uint8ClampedArray(buffer) |
-            BufferSource::BigInt64Array(buffer) |
-            BufferSource::BigUint64Array(buffer) |
-            BufferSource::Float32Array(buffer) |
-            BufferSource::Float64Array(buffer) |
-            BufferSource::DataView(buffer) |
+unsafe impl<T> crate::dom::bindings::trace::JSTraceable for HeapBufferSource<T> {
+    #[inline]
+    unsafe fn trace(&self, tracer: *mut js::jsapi::JSTracer) {
+        match &self.buffer_source {
+            BufferSource::ArrayBufferView(buffer) |
             BufferSource::ArrayBuffer(buffer) |
-            BufferSource::Default(buffer) => buffer.get(),
-        })
-    }
-
-    pub(crate) fn buffer_to_option(&self) -> Option<TypedArray<T, *mut JSObject>> {
-        if self.is_initialized() {
-            Some(self.get_buffer().expect("Failed to get buffer."))
-        } else {
-            warn!("Buffer not initialized.");
-            None
+            BufferSource::Default(buffer) => {
+                buffer.trace(tracer);
+            },
         }
     }
 }

components/script/dom/imagedata.rs

@@ -66,7 +66,7 @@ impl ImageData {
         can_gc: CanGc,
     ) -> Fallible<DomRoot<ImageData>> {
         let heap_typed_array = match new_initialized_heap_buffer_source::<ClampedU8>(
-            HeapTypedArrayInit::Buffer(BufferSource::Uint8ClampedArray(Heap::boxed(jsobject))),
+            HeapTypedArrayInit::Buffer(BufferSource::ArrayBufferView(Heap::boxed(jsobject))),
         ) {
             Ok(heap_typed_array) => heap_typed_array,
             Err(_) => return Err(Error::JSFailed),

components/script/dom/readablebytestreamcontroller.rs

@@ -4,13 +4,18 @@
 
 use dom_struct::dom_struct;
 use js::rust::HandleValue as SafeHandleValue;
+use js::typedarray::ArrayBufferViewU8;
 
+use super::bindings::buffer_source::HeapBufferSource;
+use super::bindings::codegen::Bindings::ReadableStreamBYOBReaderBinding::ReadableStreamBYOBReaderReadOptions;
+use super::readablestreambyobreader::ReadIntoRequest;
+use super::types::ReadableStreamBYOBRequest;
 use crate::dom::bindings::codegen::Bindings::ReadableByteStreamControllerBinding::ReadableByteStreamControllerMethods;
 use crate::dom::bindings::import::module::{Error, Fallible};
 use crate::dom::bindings::reflector::Reflector;
 use crate::dom::bindings::root::{DomRoot, MutNullableDom};
 use crate::dom::readablestream::ReadableStream;
-use crate::script_runtime::JSContext as SafeJSContext;
+use crate::script_runtime::{CanGc, JSContext as SafeJSContext};
 
 /// <https://streams.spec.whatwg.org/#readablebytestreamcontroller>
 #[dom_struct]
@@ -23,14 +28,22 @@ impl ReadableByteStreamController {
     pub(crate) fn set_stream(&self, stream: &ReadableStream) {
         self.stream.set(Some(stream))
     }
+
+    /// <https://streams.spec.whatwg.org/#readable-byte-stream-controller-pull-into>
+    pub(crate) fn perform_pull_into(
+        &self,
+        _read_into_request: &ReadIntoRequest,
+        _view: HeapBufferSource<ArrayBufferViewU8>,
+        _options: &ReadableStreamBYOBReaderReadOptions,
+        _can_gc: CanGc,
+    ) {
+        todo!()
+    }
 }
 
 impl ReadableByteStreamControllerMethods<crate::DomTypeHolder> for ReadableByteStreamController {
     /// <https://streams.spec.whatwg.org/#rbs-controller-byob-request>
-    fn GetByobRequest(
-        &self,
-    ) -> Fallible<Option<DomRoot<super::readablestreambyobrequest::ReadableStreamBYOBRequest>>>
-    {
+    fn GetByobRequest(&self) -> Fallible<Option<DomRoot<ReadableStreamBYOBRequest>>> {
         // TODO
         Err(Error::NotFound)
     }

components/script/dom/readablestream.rs

@@ -14,6 +14,7 @@ use js::rust::{
     HandleObject as SafeHandleObject, HandleValue as SafeHandleValue,
     MutableHandleValue as SafeMutableHandleValue,
 };
+use js::typedarray::ArrayBufferViewU8;
 
 use crate::dom::bindings::codegen::Bindings::QueuingStrategyBinding::QueuingStrategy;
 use crate::dom::bindings::codegen::Bindings::ReadableStreamBinding::{
@@ -45,6 +46,10 @@ use crate::realms::{enter_realm, InRealm};
 use crate::script_runtime::{CanGc, JSContext as SafeJSContext};
 use crate::dom::promisenativehandler::{Callback, PromiseNativeHandler};
 
+use super::bindings::buffer_source::HeapBufferSource;
+use super::bindings::codegen::Bindings::ReadableStreamBYOBReaderBinding::ReadableStreamBYOBReaderReadOptions;
+use super::readablestreambyobreader::ReadIntoRequest;
+
 /// The fulfillment handler for the reacting to sourceCancelPromise part of
 /// <https://streams.spec.whatwg.org/#readable-stream-cancel>.
 #[derive(Clone, JSTraceable, MallocSizeOf)]
@@ -296,7 +301,32 @@ impl ReadableStream {
                 .get()
                 .expect("Stream should have controller.")
                 .perform_pull_steps(read_request, can_gc),
-            ControllerType::Byte(_) => todo!(),
+            ControllerType::Byte(_) => {
+                unreachable!(
+                    "Pulling a chunk from a stream with a byte controller using a default reader"
+                )
+            },
+        }
+    }
+
+    /// Call into the pull steps of the controller,
+    /// as part of
+    /// <https://streams.spec.whatwg.org/#readable-stream-byob-reader-read>
+    pub(crate) fn perform_pull_into_steps(
+        &self,
+        read_into_request: &ReadIntoRequest,
+        view: HeapBufferSource<ArrayBufferViewU8>,
+        options: &ReadableStreamBYOBReaderReadOptions,
+        can_gc: CanGc,
+    ) {
+        match self.controller {
+            ControllerType::Byte(ref controller) => controller
+                .get()
+                .expect("Stream should have controller.")
+                .perform_pull_into(read_into_request, view, options, can_gc),
+            ControllerType::Default(_) => unreachable!(
+                "Pulling a chunk from a stream with a default controller using a BYOB reader"
+            ),
         }
     }
 
@@ -321,6 +351,28 @@ impl ReadableStream {
         }
     }
 
+    #[allow(dead_code)]
+    /// <https://streams.spec.whatwg.org/#readable-stream-add-read-into-request>
+    pub(crate) fn add_read_into_request(&self, read_request: &ReadIntoRequest) {
+        match self.reader {
+            // Assert: stream.[[reader]] implements ReadableStreamBYOBReader.
+            ReaderType::Default(_) => {
+                unreachable!("Adding a read into request can only be done on a BYOB reader.")
+            },
+            ReaderType::BYOB(ref reader) => {
+                let Some(reader) = reader.get() else {
+                    unreachable!("Attempt to add a read into request without having first acquired a reader.");
+                };
+
+                // Assert: stream.[[state]] is "readable" or "closed".
+                assert!(self.is_readable() || self.is_closed());
+
+                // Append readRequest to stream.[[reader]].[[readIntoRequests]].
+                reader.add_read_into_request(read_request);
+            },
+        }
+    }
+
     /// Endpoint to enqueue chunks directly from Rust.
     /// Note: in other use cases this call happens via the controller.
     pub(crate) fn enqueue_native(&self, bytes: Vec<u8>) {

components/script/dom/readablestreambyobreader.rs

@@ -12,8 +12,11 @@ use js::gc::CustomAutoRooterGuard;
 use js::jsapi::Heap;
 use js::jsval::{JSVal, UndefinedValue};
 use js::rust::{HandleObject as SafeHandleObject, HandleValue as SafeHandleValue};
-use js::typedarray::ArrayBufferView;
+use js::typedarray::{ArrayBufferView, ArrayBufferViewU8};
 
+use super::bindings::buffer_source::{BufferSource, HeapBufferSource};
+use super::bindings::codegen::Bindings::ReadableStreamBYOBReaderBinding::ReadableStreamBYOBReaderReadOptions;
+use super::bindings::codegen::Bindings::ReadableStreamDefaultReaderBinding::ReadableStreamReadResult;
 use super::bindings::reflector::reflect_dom_object;
 use super::readablestreamgenericreader::ReadableStreamGenericReader;
 use crate::dom::bindings::cell::DomRefCell;
@@ -29,26 +32,49 @@ use crate::dom::readablestream::ReadableStream;
 use crate::script_runtime::{CanGc, JSContext as SafeJSContext};
 
 /// <https://streams.spec.whatwg.org/#read-into-request>
-#[derive(JSTraceable, MallocSizeOf)]
+#[derive(Clone, JSTraceable, MallocSizeOf)]
 pub enum ReadIntoRequest {
     /// <https://streams.spec.whatwg.org/#byob-reader-read>
     Read(#[ignore_malloc_size_of = "Rc is hard"] Rc<Promise>),
 }
 
 impl ReadIntoRequest {
-    /// <https://streams.spec.whatwg.org/#read-into-request-chunk-steps>
-    pub fn chunk_steps(&self, _chunk: RootedTraceableBox<Heap<JSVal>>) {
-        todo!()
+    /// <https://streams.spec.whatwg.org/#ref-for-read-into-request-chunk-steps>
+    pub fn chunk_steps(&self, chunk: RootedTraceableBox<Heap<JSVal>>) {
+        // chunk steps, given chunk
+        // Resolve promise with «[ "value" → chunk, "done" → false ]».
+        match self {
+            ReadIntoRequest::Read(promise) => {
+                promise.resolve_native(&ReadableStreamReadResult {
+                    done: Some(false),
+                    value: chunk,
+                });
+            },
+        }
     }
 
-    /// <https://streams.spec.whatwg.org/#read-into-request-close-steps>
-    pub fn close_steps(&self, _chunk: Option<RootedTraceableBox<Heap<JSVal>>>) {
-        todo!()
+    /// <https://streams.spec.whatwg.org/#ref-for-read-into-request-close-steps%E2%91%A0>
+    pub fn close_steps(&self, chunk: Option<RootedTraceableBox<Heap<JSVal>>>) {
+        // close steps, given chunk
+        // Resolve promise with «[ "value" → chunk, "done" → true ]».
+        match self {
+            ReadIntoRequest::Read(promise) => match chunk {
+                Some(chunk) => promise.resolve_native(&ReadableStreamReadResult {
+                    done: Some(true),
+                    value: chunk,
+                }),
+                None => promise.resolve_native(&()),
+            },
+        }
     }
 
-    /// <https://streams.spec.whatwg.org/#read-into-request-error-steps>
-    pub(crate) fn error_steps(&self, _e: SafeHandleValue) {
-        todo!()
+    /// <https://streams.spec.whatwg.org/#ref-for-read-into-request-error-steps>
+    pub(crate) fn error_steps(&self, e: SafeHandleValue) {
+        // error steps, given e
+        // Reject promise with e.
+        match self {
+            ReadIntoRequest::Read(promise) => promise.reject_native(&e),
+        }
     }
 }
 
@@ -163,6 +189,13 @@ impl ReadableStreamBYOBReader {
         mem::take(&mut *self.read_into_requests.borrow_mut())
     }
 
+    /// <https://streams.spec.whatwg.org/#readable-stream-add-read-into-request>
+    pub(crate) fn add_read_into_request(&self, read_request: &ReadIntoRequest) {
+        self.read_into_requests
+            .borrow_mut()
+            .push_back(read_request.clone());
+    }
+
     /// <https://streams.spec.whatwg.org/#readable-stream-cancel>
     pub(crate) fn close(&self) {
         // If reader is not undefined and reader implements ReadableStreamBYOBReader,
@@ -175,6 +208,36 @@ impl ReadableStreamBYOBReader {
             request.close_steps(None);
         }
     }
+
+    /// <https://streams.spec.whatwg.org/#readable-stream-byob-reader-read>
+    pub(crate) fn read(
+        &self,
+        view: HeapBufferSource<ArrayBufferViewU8>,
+        options: &ReadableStreamBYOBReaderReadOptions,
+        read_into_request: &ReadIntoRequest,
+        can_gc: CanGc,
+    ) {
+        // Let stream be reader.[[stream]].
+
+        // Assert: stream is not undefined.
+        assert!(self.stream.get().is_some());
+
+        let stream = self.stream.get().unwrap();
+
+        // Set stream.[[disturbed]] to true.
+        stream.set_is_disturbed(true);
+        // If stream.[[state]] is "errored", perform readIntoRequest’s error steps given stream.[[storedError]].
+        if stream.is_errored() {
+            let cx = GlobalScope::get_cx();
+            rooted!(in(*cx) let mut error = UndefinedValue());
+            stream.get_stored_error(error.handle_mut());
+            read_into_request.error_steps(error.handle());
+        } else {
+            // Otherwise,
+            // perform ! ReadableByteStreamControllerPullInto(stream.[[controller]], view, min, readIntoRequest).
+            stream.perform_pull_into_steps(read_into_request, view, options, can_gc);
+        }
+    }
 }
 
 impl ReadableStreamBYOBReaderMethods<crate::DomTypeHolder> for ReadableStreamBYOBReader {
@@ -194,9 +257,85 @@ impl ReadableStreamBYOBReaderMethods<crate::DomTypeHolder> for ReadableStreamBYO
     }
 
     /// <https://streams.spec.whatwg.org/#byob-reader-read>
-    fn Read(&self, _view: CustomAutoRooterGuard<ArrayBufferView>, can_gc: CanGc) -> Rc<Promise> {
-        // TODO
-        Promise::new(&self.reflector_.global(), can_gc)
+    #[allow(unsafe_code)]
+    fn Read(
+        &self,
+        view: CustomAutoRooterGuard<ArrayBufferView>,
+        options: &ReadableStreamBYOBReaderReadOptions,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        let view = HeapBufferSource::<ArrayBufferViewU8>::new(BufferSource::ArrayBufferView(
+            Heap::boxed(unsafe { *view.underlying_object() }),
+        ));
+
+        // Let promise be a new promise.
+        let promise = Promise::new(&self.global(), can_gc);
+
+        let cx = GlobalScope::get_cx();
+        // If view.[[ByteLength]] is 0, return a promise rejected with a TypeError exception.
+        if view.byte_length() == 0 {
+            promise.reject_error(Error::Type("view byte length is 0".to_owned()));
+            return promise;
+        }
+        // If view.[[ViewedArrayBuffer]].[[ArrayBufferByteLength]] is 0,
+        // return a promise rejected with a TypeError exception.
+        if view.viewed_buffer_array_byte_length(cx) == 0 {
+            promise.reject_error(Error::Type("viewed buffer byte length is 0".to_owned()));
+            return promise;
+        }
+
+        // If ! IsDetachedBuffer(view.[[ViewedArrayBuffer]]) is true,
+        // return a promise rejected with a TypeError exception.
+        if view.is_detached_buffer(cx) {
+            promise.reject_error(Error::Type("view is detached".to_owned()));
+            return promise;
+        }
+
+        // If options["min"] is 0, return a promise rejected with a TypeError exception.
+        if options.min == 0 {
+            promise.reject_error(Error::Type("min is 0".to_owned()));
+            return promise;
+        }
+
+        // If view has a [[TypedArrayName]] internal slot,
+        if view.has_typed_array_name() {
+            // If options["min"] > view.[[ArrayLength]], return a promise rejected with a RangeError exception.
+            if options.min > (view.array_length() as u64) {
+                promise.reject_error(Error::Type("min is greater than array length".to_owned()));
+                return promise;
+            }
+        } else {
+            // Otherwise (i.e., it is a DataView),
+            // If options["min"] > view.[[ByteLength]], return a promise rejected with a RangeError exception.
+            if options.min > (view.byte_length() as u64) {
+                promise.reject_error(Error::Type("min is greater than byte length".to_owned()));
+                return promise;
+            }
+        }
+
+        // If this.[[stream]] is undefined, return a promise rejected with a TypeError exception.
+        if self.stream.get().is_none() {
+            promise.reject_error(Error::Type("min is greater than byte length".to_owned()));
+            return promise;
+        }
+
+        // Let readIntoRequest be a new read-into request with the following items:
+        //
+        // chunk steps, given chunk
+        // Resolve promise with «[ "value" → chunk, "done" → false ]».
+        //
+        // close steps, given chunk
+        // Resolve promise with «[ "value" → chunk, "done" → true ]».
+        //
+        // error steps, given e
+        // Reject promise with e
+        let read_into_request = ReadIntoRequest::Read(promise.clone());
+
+        // Perform ! ReadableStreamBYOBReaderRead(this, view, options["min"], readIntoRequest).
+        self.read(view, options, &read_into_request, can_gc);
+
+        // Return promise.
+        promise
     }
 
     /// <https://streams.spec.whatwg.org/#byob-reader-release-lock>

components/script/dom/readablestreamdefaultreader.rs

@@ -49,6 +49,8 @@ impl ReadRequest {
     pub(crate) fn chunk_steps(&self, chunk: RootedTraceableBox<Heap<JSVal>>) {
         match self {
             ReadRequest::Read(promise) => {
+                // chunk steps, given chunk
+                // Resolve promise with «[ "value" → chunk, "done" → false ]».
                 promise.resolve_native(&ReadableStreamReadResult {
                     done: Some(false),
                     value: chunk,
@@ -64,6 +66,8 @@ impl ReadRequest {
     pub(crate) fn close_steps(&self) {
         match self {
             ReadRequest::Read(promise) => {
+                // close steps
+                // Resolve promise with «[ "value" → undefined, "done" → true ]».
                 let result = RootedTraceableBox::new(Heap::default());
                 result.set(UndefinedValue());
                 promise.resolve_native(&ReadableStreamReadResult {
@@ -80,7 +84,11 @@ impl ReadRequest {
     /// <https://streams.spec.whatwg.org/#read-request-error-steps>
     pub(crate) fn error_steps(&self, e: SafeHandleValue) {
         match self {
-            ReadRequest::Read(promise) => promise.reject_native(&e),
+            ReadRequest::Read(promise) => {
+                // error steps, given e
+                // Reject promise with e.
+                promise.reject_native(&e)
+            },
             ReadRequest::DefaultTee { tee_read_request } => {
                 tee_read_request.error_steps();
             },

components/script_bindings/webidls/ReadableStreamBYOBReader.webidl

@@ -10,10 +10,15 @@ interface ReadableStreamBYOBReader {
   constructor(ReadableStream stream);
 
   [NewObject]
-  Promise<ReadableStreamReadResult> read(ArrayBufferView view);
+  Promise<ReadableStreamReadResult> read(ArrayBufferView view,
+      optional ReadableStreamBYOBReaderReadOptions options = {}
+  );
 
   [Throws]
   undefined releaseLock();
 };
 ReadableStreamBYOBReader includes ReadableStreamGenericReader;
 
+dictionary ReadableStreamBYOBReaderReadOptions {
+  [EnforceRange] unsigned long long min = 1;
+};