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//! Boa's implementation of ECMAScript's global `ArrayBuffer` and `SharedArrayBuffer` objects
//!
//! More information:
//! - [ECMAScript reference][spec]
//! - [MDN documentation][mdn]
//!
//! [spec]: https://tc39.es/ecma262/#sec-arraybuffer-objects
//! [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer
#![deny(unsafe_op_in_unsafe_fn)]
#![deny(clippy::undocumented_unsafe_blocks)]
pub(crate) mod shared;
pub(crate) mod utils;
#[cfg(test)]
mod tests;
use std::ops::{Deref, DerefMut};
pub use shared::SharedArrayBuffer;
use std::sync::atomic::Ordering;
use crate::{
builtins::BuiltInObject,
context::intrinsics::{Intrinsics, StandardConstructor, StandardConstructors},
error::JsNativeError,
js_string,
object::{internal_methods::get_prototype_from_constructor, JsObject, Object},
property::Attribute,
realm::Realm,
string::common::StaticJsStrings,
symbol::JsSymbol,
Context, JsArgs, JsData, JsResult, JsString, JsValue,
};
use boa_gc::{Finalize, GcRef, GcRefMut, Trace};
use boa_profiler::Profiler;
use self::utils::{SliceRef, SliceRefMut};
use super::{
typed_array::TypedArray, Array, BuiltInBuilder, BuiltInConstructor, DataView, IntrinsicObject,
};
#[derive(Debug, Clone, Copy)]
pub(crate) enum BufferRef<B, S> {
Buffer(B),
SharedBuffer(S),
}
impl<B, S> BufferRef<B, S>
where
B: Deref<Target = ArrayBuffer>,
S: Deref<Target = SharedArrayBuffer>,
{
/// Gets the inner data of the buffer.
pub(crate) fn bytes(&self, ordering: Ordering) -> Option<SliceRef<'_>> {
match self {
Self::Buffer(buf) => buf.deref().bytes().map(SliceRef::Slice),
Self::SharedBuffer(buf) => Some(SliceRef::AtomicSlice(buf.deref().bytes(ordering))),
}
}
/// Gets the inner data of the buffer without accessing the current atomic length.
///
/// Returns `None` if the buffer is detached or if the provided `len` is bigger than
/// the allocated buffer.
#[track_caller]
pub(crate) fn bytes_with_len(&self, len: usize) -> Option<SliceRef<'_>> {
match self {
Self::Buffer(buf) => buf.deref().bytes_with_len(len).map(SliceRef::Slice),
Self::SharedBuffer(buf) => Some(SliceRef::AtomicSlice(buf.deref().bytes_with_len(len))),
}
}
pub(crate) fn is_fixed_len(&self) -> bool {
match self {
Self::Buffer(buf) => buf.is_fixed_len(),
Self::SharedBuffer(buf) => buf.is_fixed_len(),
}
}
}
#[derive(Debug)]
pub(crate) enum BufferRefMut<B, S> {
Buffer(B),
SharedBuffer(S),
}
impl<B, S> BufferRefMut<B, S>
where
B: DerefMut<Target = ArrayBuffer>,
S: DerefMut<Target = SharedArrayBuffer>,
{
pub(crate) fn bytes(&mut self, ordering: Ordering) -> Option<SliceRefMut<'_>> {
match self {
Self::Buffer(buf) => buf.deref_mut().bytes_mut().map(SliceRefMut::Slice),
Self::SharedBuffer(buf) => {
Some(SliceRefMut::AtomicSlice(buf.deref_mut().bytes(ordering)))
}
}
}
/// Gets the mutable inner data of the buffer without accessing the current atomic length.
///
/// Returns `None` if the buffer is detached or if the provided `len` is bigger than
/// the allocated buffer.
pub(crate) fn bytes_with_len(&mut self, len: usize) -> Option<SliceRefMut<'_>> {
match self {
Self::Buffer(buf) => buf
.deref_mut()
.bytes_with_len_mut(len)
.map(SliceRefMut::Slice),
Self::SharedBuffer(buf) => Some(SliceRefMut::AtomicSlice(
buf.deref_mut().bytes_with_len(len),
)),
}
}
}
/// A `JsObject` containing a bytes buffer as its inner data.
#[derive(Debug, Clone, Trace, Finalize)]
#[boa_gc(unsafe_no_drop)]
pub(crate) enum BufferObject {
Buffer(JsObject<ArrayBuffer>),
SharedBuffer(JsObject<SharedArrayBuffer>),
}
impl From<BufferObject> for JsObject {
fn from(value: BufferObject) -> Self {
match value {
BufferObject::Buffer(buf) => buf.upcast(),
BufferObject::SharedBuffer(buf) => buf.upcast(),
}
}
}
impl From<BufferObject> for JsValue {
fn from(value: BufferObject) -> Self {
JsValue::from(JsObject::from(value))
}
}
impl BufferObject {
/// Gets the buffer data of the object.
#[inline]
#[must_use]
pub(crate) fn as_buffer(
&self,
) -> BufferRef<GcRef<'_, ArrayBuffer>, GcRef<'_, SharedArrayBuffer>> {
match self {
Self::Buffer(buf) => BufferRef::Buffer(GcRef::map(buf.borrow(), |o| &o.data)),
Self::SharedBuffer(buf) => {
BufferRef::SharedBuffer(GcRef::map(buf.borrow(), |o| &o.data))
}
}
}
/// Gets the mutable buffer data of the object
#[inline]
pub(crate) fn as_buffer_mut(
&self,
) -> BufferRefMut<
GcRefMut<'_, Object<ArrayBuffer>, ArrayBuffer>,
GcRefMut<'_, Object<SharedArrayBuffer>, SharedArrayBuffer>,
> {
match self {
Self::Buffer(buf) => {
BufferRefMut::Buffer(GcRefMut::map(buf.borrow_mut(), |o| &mut o.data))
}
Self::SharedBuffer(buf) => {
BufferRefMut::SharedBuffer(GcRefMut::map(buf.borrow_mut(), |o| &mut o.data))
}
}
}
/// Returns `true` if the buffer objects point to the same buffer.
#[inline]
pub(crate) fn equals(lhs: &Self, rhs: &Self) -> bool {
match (lhs, rhs) {
(BufferObject::Buffer(lhs), BufferObject::Buffer(rhs)) => JsObject::equals(lhs, rhs),
(BufferObject::SharedBuffer(lhs), BufferObject::SharedBuffer(rhs)) => {
if JsObject::equals(lhs, rhs) {
return true;
}
let lhs = lhs.borrow();
let rhs = rhs.borrow();
std::ptr::eq(lhs.data.as_ptr(), rhs.data.as_ptr())
}
_ => false,
}
}
}
/// The internal representation of an `ArrayBuffer` object.
#[derive(Debug, Clone, Trace, Finalize, JsData)]
pub struct ArrayBuffer {
/// The `[[ArrayBufferData]]` internal slot.
data: Option<Vec<u8>>,
/// The `[[ArrayBufferMaxByteLength]]` internal slot.
max_byte_len: Option<u64>,
/// The `[[ArrayBufferDetachKey]]` internal slot.
detach_key: JsValue,
}
impl ArrayBuffer {
pub(crate) fn from_data(data: Vec<u8>, detach_key: JsValue) -> Self {
Self {
data: Some(data),
max_byte_len: None,
detach_key,
}
}
pub(crate) fn len(&self) -> usize {
self.data.as_ref().map_or(0, Vec::len)
}
pub(crate) fn bytes(&self) -> Option<&[u8]> {
self.data.as_deref()
}
pub(crate) fn bytes_mut(&mut self) -> Option<&mut [u8]> {
self.data.as_deref_mut()
}
pub(crate) fn vec_mut(&mut self) -> Option<&mut Vec<u8>> {
self.data.as_mut()
}
/// Gets the inner bytes of the buffer without accessing the current atomic length.
#[track_caller]
pub(crate) fn bytes_with_len(&self, len: usize) -> Option<&[u8]> {
if let Some(s) = self.data.as_deref() {
Some(&s[..len])
} else {
None
}
}
/// Gets the mutable inner bytes of the buffer without accessing the current atomic length.
#[track_caller]
pub(crate) fn bytes_with_len_mut(&mut self, len: usize) -> Option<&mut [u8]> {
if let Some(s) = self.data.as_deref_mut() {
Some(&mut s[..len])
} else {
None
}
}
/// Detaches the inner data of this `ArrayBuffer`, returning the original buffer if still
/// present.
///
/// # Errors
///
/// Throws an error if the provided detach key is invalid.
pub fn detach(&mut self, key: &JsValue) -> JsResult<Option<Vec<u8>>> {
if !JsValue::same_value(&self.detach_key, key) {
return Err(JsNativeError::typ()
.with_message("Cannot detach array buffer with different key")
.into());
}
Ok(self.data.take())
}
/// `IsDetachedBuffer ( arrayBuffer )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-isdetachedbuffer
pub(crate) const fn is_detached(&self) -> bool {
// 1. If arrayBuffer.[[ArrayBufferData]] is null, return true.
// 2. Return false.
self.data.is_none()
}
pub(crate) fn is_fixed_len(&self) -> bool {
self.max_byte_len.is_none()
}
}
impl IntrinsicObject for ArrayBuffer {
fn init(realm: &Realm) {
let _timer = Profiler::global().start_event(std::any::type_name::<Self>(), "init");
let flag_attributes = Attribute::CONFIGURABLE | Attribute::NON_ENUMERABLE;
let get_species = BuiltInBuilder::callable(realm, Self::get_species)
.name(js_string!("get [Symbol.species]"))
.build();
let get_byte_length = BuiltInBuilder::callable(realm, Self::get_byte_length)
.name(js_string!("get byteLength"))
.build();
let get_resizable = BuiltInBuilder::callable(realm, Self::get_resizable)
.name(js_string!("get resizable"))
.build();
let get_max_byte_length = BuiltInBuilder::callable(realm, Self::get_max_byte_length)
.name(js_string!("get maxByteLength"))
.build();
#[cfg(feature = "experimental")]
let get_detached = BuiltInBuilder::callable(realm, Self::get_detached)
.name(js_string!("get detached"))
.build();
let builder = BuiltInBuilder::from_standard_constructor::<Self>(realm)
.static_accessor(
JsSymbol::species(),
Some(get_species),
None,
Attribute::CONFIGURABLE,
)
.static_method(Self::is_view, js_string!("isView"), 1)
.accessor(
js_string!("byteLength"),
Some(get_byte_length),
None,
flag_attributes,
)
.accessor(
js_string!("resizable"),
Some(get_resizable),
None,
flag_attributes,
)
.accessor(
js_string!("maxByteLength"),
Some(get_max_byte_length),
None,
flag_attributes,
)
.method(Self::resize, js_string!("resize"), 1)
.method(Self::slice, js_string!("slice"), 2)
.property(
JsSymbol::to_string_tag(),
Self::NAME,
Attribute::READONLY | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
);
#[cfg(feature = "experimental")]
let builder = builder
.accessor(
js_string!("detached"),
Some(get_detached),
None,
flag_attributes,
)
.method(Self::transfer::<false>, js_string!("transfer"), 0)
.method(
Self::transfer::<true>,
js_string!("transferToFixedLength"),
0,
);
builder.build();
}
fn get(intrinsics: &Intrinsics) -> JsObject {
Self::STANDARD_CONSTRUCTOR(intrinsics.constructors()).constructor()
}
}
impl BuiltInObject for ArrayBuffer {
const NAME: JsString = StaticJsStrings::ARRAY_BUFFER;
}
impl BuiltInConstructor for ArrayBuffer {
const LENGTH: usize = 1;
const STANDARD_CONSTRUCTOR: fn(&StandardConstructors) -> &StandardConstructor =
StandardConstructors::array_buffer;
/// `ArrayBuffer ( length )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-arraybuffer-length
fn constructor(
new_target: &JsValue,
args: &[JsValue],
context: &mut Context,
) -> JsResult<JsValue> {
// 1. If NewTarget is undefined, throw a TypeError exception.
if new_target.is_undefined() {
return Err(JsNativeError::typ()
.with_message("ArrayBuffer.constructor called with undefined new target")
.into());
}
// 2. Let byteLength be ? ToIndex(length).
let byte_len = args.get_or_undefined(0).to_index(context)?;
// 3. Let requestedMaxByteLength be ? GetArrayBufferMaxByteLengthOption(options).
let max_byte_len = get_max_byte_len(args.get_or_undefined(1), context)?;
// 4. Return ? AllocateArrayBuffer(NewTarget, byteLength, requestedMaxByteLength).
Ok(Self::allocate(new_target, byte_len, max_byte_len, context)?
.upcast()
.into())
}
}
impl ArrayBuffer {
/// `ArrayBuffer.isView ( arg )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-arraybuffer.isview
#[allow(clippy::unnecessary_wraps)]
fn is_view(_: &JsValue, args: &[JsValue], _context: &mut Context) -> JsResult<JsValue> {
// 1. If Type(arg) is not Object, return false.
// 2. If arg has a [[ViewedArrayBuffer]] internal slot, return true.
// 3. Return false.
Ok(args
.get_or_undefined(0)
.as_object()
.map(|obj| obj.is::<TypedArray>() || obj.is::<DataView>())
.unwrap_or_default()
.into())
}
/// `get ArrayBuffer [ @@species ]`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-get-arraybuffer-@@species
#[allow(clippy::unnecessary_wraps)]
fn get_species(this: &JsValue, _: &[JsValue], _: &mut Context) -> JsResult<JsValue> {
// 1. Return the this value.
Ok(this.clone())
}
/// `get ArrayBuffer.prototype.byteLength`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-get-arraybuffer.prototype.bytelength
pub(crate) fn get_byte_length(
this: &JsValue,
_args: &[JsValue],
_: &mut Context,
) -> JsResult<JsValue> {
// 1. Let O be the this value.
// 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
// 3. If IsSharedArrayBuffer(O) is true, throw a TypeError exception.
let buf = this
.as_object()
.and_then(JsObject::downcast_ref::<Self>)
.ok_or_else(|| {
JsNativeError::typ()
.with_message("get ArrayBuffer.prototype.byteLength called with invalid `this`")
})?;
// 4. If IsDetachedBuffer(O) is true, return +0𝔽.
// 5. Let length be O.[[ArrayBufferByteLength]].
// 6. Return 𝔽(length).
Ok(buf.len().into())
}
/// [`get ArrayBuffer.prototype.maxByteLength`][spec].
///
/// [spec]: https://tc39.es/ecma262/#sec-get-arraybuffer.prototype.maxbytelength
pub(crate) fn get_max_byte_length(
this: &JsValue,
_args: &[JsValue],
_context: &mut Context,
) -> JsResult<JsValue> {
// 1. Let O be the this value.
// 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
// 3. If IsSharedArrayBuffer(O) is true, throw a TypeError exception.
let buf = this
.as_object()
.and_then(JsObject::downcast_ref::<Self>)
.ok_or_else(|| {
JsNativeError::typ().with_message(
"get ArrayBuffer.prototype.maxByteLength called with invalid `this`",
)
})?;
// 4. If IsDetachedBuffer(O) is true, return +0𝔽.
let Some(data) = buf.bytes() else {
return Ok(JsValue::from(0));
};
// 5. If IsFixedLengthArrayBuffer(O) is true, then
// a. Let length be O.[[ArrayBufferByteLength]].
// 6. Else,
// a. Let length be O.[[ArrayBufferMaxByteLength]].
// 7. Return 𝔽(length).
Ok(buf.max_byte_len.unwrap_or(data.len() as u64).into())
}
/// [`get ArrayBuffer.prototype.resizable`][spec].
///
/// [spec]: https://tc39.es/ecma262/#sec-get-arraybuffer.prototype.resizable
pub(crate) fn get_resizable(
this: &JsValue,
_args: &[JsValue],
_context: &mut Context,
) -> JsResult<JsValue> {
// 1. Let O be the this value.
// 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
// 3. If IsSharedArrayBuffer(O) is true, throw a TypeError exception.
let buf = this
.as_object()
.and_then(JsObject::downcast_ref::<Self>)
.ok_or_else(|| {
JsNativeError::typ()
.with_message("get ArrayBuffer.prototype.resizable called with invalid `this`")
})?;
// 4. If IsFixedLengthArrayBuffer(O) is false, return true; otherwise return false.
Ok(JsValue::from(!buf.is_fixed_len()))
}
/// [`get ArrayBuffer.prototype.detached`][spec].
///
/// [spec]: https://tc39.es/proposal-arraybuffer-transfer/#sec-get-arraybuffer.prototype.detached
#[cfg(feature = "experimental")]
fn get_detached(
this: &JsValue,
_args: &[JsValue],
_context: &mut Context,
) -> JsResult<JsValue> {
// 1. Let O be the this value.
// 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
// 3. If IsSharedArrayBuffer(O) is true, throw a TypeError exception.
let buf = this
.as_object()
.and_then(JsObject::downcast_ref::<Self>)
.ok_or_else(|| {
JsNativeError::typ()
.with_message("get ArrayBuffer.prototype.detached called with invalid `this`")
})?;
// 4. Return IsDetachedBuffer(O).
Ok(buf.is_detached().into())
}
/// [`ArrayBuffer.prototype.resize ( newLength )`][spec].
///
/// [spec]: https://tc39.es/ecma262/#sec-arraybuffer.prototype.resize
pub(crate) fn resize(
this: &JsValue,
args: &[JsValue],
context: &mut Context,
) -> JsResult<JsValue> {
// 1. Let O be the this value.
// 2. Perform ? RequireInternalSlot(O, [[ArrayBufferMaxByteLength]]).
// 3. If IsSharedArrayBuffer(O) is true, throw a TypeError exception.
let buf = this
.as_object()
.and_then(|o| o.clone().downcast::<Self>().ok())
.ok_or_else(|| {
JsNativeError::typ()
.with_message("ArrayBuffer.prototype.resize called with invalid `this`")
})?;
let Some(max_byte_len) = buf.borrow().data.max_byte_len else {
return Err(JsNativeError::typ()
.with_message("ArrayBuffer.resize: cannot resize a fixed-length buffer")
.into());
};
// 4. Let newByteLength be ? ToIndex(newLength).
let new_byte_length = args.get_or_undefined(0).to_index(context)?;
let mut buf = buf.borrow_mut();
// 5. If IsDetachedBuffer(O) is true, throw a TypeError exception.
let Some(buf) = buf.data.vec_mut() else {
return Err(JsNativeError::typ()
.with_message("ArrayBuffer.resize: cannot resize a detached buffer")
.into());
};
// 6. If newByteLength > O.[[ArrayBufferMaxByteLength]], throw a RangeError exception.
if new_byte_length > max_byte_len {
return Err(JsNativeError::range()
.with_message(
"ArrayBuffer.resize: new byte length exceeds buffer's maximum byte length",
)
.into());
}
// TODO: 7. Let hostHandled be ? HostResizeArrayBuffer(O, newByteLength).
// 8. If hostHandled is handled, return undefined.
// Used in engines to handle WASM buffers in a special way, but we don't
// have a WASM interpreter in place yet.
// 9. Let oldBlock be O.[[ArrayBufferData]].
// 10. Let newBlock be ? CreateByteDataBlock(newByteLength).
// 11. Let copyLength be min(newByteLength, O.[[ArrayBufferByteLength]]).
// 12. Perform CopyDataBlockBytes(newBlock, 0, oldBlock, 0, copyLength).
// 13. NOTE: Neither creation of the new Data Block nor copying from the old Data Block are observable.
// Implementations may implement this method as in-place growth or shrinkage.
// 14. Set O.[[ArrayBufferData]] to newBlock.
// 15. Set O.[[ArrayBufferByteLength]] to newByteLength.
buf.resize(new_byte_length as usize, 0);
// 16. Return undefined.
Ok(JsValue::undefined())
}
/// `ArrayBuffer.prototype.slice ( start, end )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-arraybuffer.prototype.slice
fn slice(this: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
// 1. Let O be the this value.
// 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
// 3. If IsSharedArrayBuffer(O) is true, throw a TypeError exception.
let buf = this
.as_object()
.and_then(|o| o.clone().downcast::<Self>().ok())
.ok_or_else(|| {
JsNativeError::typ()
.with_message("ArrayBuffer.slice called with invalid `this` value")
})?;
let len = {
let buf = buf.borrow();
// 4. If IsDetachedBuffer(O) is true, throw a TypeError exception.
if buf.data.is_detached() {
return Err(JsNativeError::typ()
.with_message("ArrayBuffer.slice called with detached buffer")
.into());
}
// 5. Let len be O.[[ArrayBufferByteLength]].
buf.data.len() as u64
};
// 6. Let relativeStart be ? ToIntegerOrInfinity(start).
// 7. If relativeStart = -∞, let first be 0.
// 8. Else if relativeStart < 0, let first be max(len + relativeStart, 0).
// 9. Else, let first be min(relativeStart, len).
let first = Array::get_relative_start(context, args.get_or_undefined(0), len)?;
// 10. If end is undefined, let relativeEnd be len; else let relativeEnd be ? ToIntegerOrInfinity(end).
// 11. If relativeEnd = -∞, let final be 0.
// 12. Else if relativeEnd < 0, let final be max(len + relativeEnd, 0).
// 13. Else, let final be min(relativeEnd, len).
let final_ = Array::get_relative_end(context, args.get_or_undefined(1), len)?;
// 14. Let newLen be max(final - first, 0).
let new_len = final_.saturating_sub(first);
// 15. Let ctor be ? SpeciesConstructor(O, %ArrayBuffer%).
let ctor = buf
.clone()
.upcast()
.species_constructor(StandardConstructors::array_buffer, context)?;
// 16. Let new be ? Construct(ctor, « 𝔽(newLen) »).
let new = ctor.construct(&[new_len.into()], Some(&ctor), context)?;
// 17. Perform ? RequireInternalSlot(new, [[ArrayBufferData]]).
// 18. If IsSharedArrayBuffer(new) is true, throw a TypeError exception.
let Ok(new) = new.downcast::<Self>() else {
return Err(JsNativeError::typ()
.with_message("ArrayBuffer constructor returned invalid object")
.into());
};
// 20. If SameValue(new, O) is true, throw a TypeError exception.
if JsObject::equals(&buf, &new) {
return Err(JsNativeError::typ()
.with_message("new ArrayBuffer is the same as this ArrayBuffer")
.into());
}
{
// 19. If IsDetachedBuffer(new) is true, throw a TypeError exception.
// 25. Let toBuf be new.[[ArrayBufferData]].
let mut new = new.borrow_mut();
let Some(to_buf) = new.data.bytes_mut() else {
return Err(JsNativeError::typ()
.with_message("ArrayBuffer constructor returned detached ArrayBuffer")
.into());
};
// 21. If new.[[ArrayBufferByteLength]] < newLen, throw a TypeError exception.
if (to_buf.len() as u64) < new_len {
return Err(JsNativeError::typ()
.with_message("new ArrayBuffer length too small")
.into());
}
// 22. NOTE: Side-effects of the above steps may have detached O.
// 23. If IsDetachedBuffer(O) is true, throw a TypeError exception.
// 24. Let fromBuf be O.[[ArrayBufferData]].
let buf = buf.borrow();
let Some(from_buf) = buf.data.bytes() else {
return Err(JsNativeError::typ()
.with_message("ArrayBuffer detached while ArrayBuffer.slice was running")
.into());
};
// 26. Perform CopyDataBlockBytes(toBuf, 0, fromBuf, first, newLen).
let first = first as usize;
let new_len = new_len as usize;
to_buf[..new_len].copy_from_slice(&from_buf[first..first + new_len]);
}
// 27. Return new.
Ok(new.upcast().into())
}
/// [`ArrayBuffer.prototype.transfer ( [ newLength ] )`][transfer] and
/// [`ArrayBuffer.prototype.transferToFixedLength ( [ newLength ] )`][transferFL]
///
/// [transfer]: https://tc39.es/proposal-arraybuffer-transfer/#sec-arraybuffer.prototype.transfer
/// [transferFL]: https://tc39.es/proposal-arraybuffer-transfer/#sec-arraybuffer.prototype.transfertofixedlength
#[cfg(feature = "experimental")]
fn transfer<const TO_FIXED_LENGTH: bool>(
this: &JsValue,
args: &[JsValue],
context: &mut Context,
) -> JsResult<JsValue> {
// 1. Let O be the this value.
// 2. Return ? ArrayBufferCopyAndDetach(O, newLength, preserve-resizability).
// Abstract operation `ArrayBufferCopyAndDetach ( arrayBuffer, newLength, preserveResizability )`
// https://tc39.es/proposal-arraybuffer-transfer/#sec-arraybuffercopyanddetach
let new_length = args.get_or_undefined(0);
// 1. Perform ? RequireInternalSlot(arrayBuffer, [[ArrayBufferData]]).
// 2. If IsSharedArrayBuffer(arrayBuffer) is true, throw a TypeError exception.
let buf = this
.as_object()
.and_then(|o| o.clone().downcast::<Self>().ok())
.ok_or_else(|| {
JsNativeError::typ().with_message(if TO_FIXED_LENGTH {
"ArrayBuffer.prototype.transferToFixedLength called with invalid `this`"
} else {
"ArrayBuffer.prototype.transfer called with invalid `this`"
})
})?;
// 3. If newLength is undefined, then
let new_len = if new_length.is_undefined() {
// a. Let newByteLength be arrayBuffer.[[ArrayBufferByteLength]].
buf.borrow().data.len() as u64
} else {
// 4. Else,
// a. Let newByteLength be ? ToIndex(newLength).
new_length.to_index(context)?
};
// 5. If IsDetachedBuffer(arrayBuffer) is true, throw a TypeError exception.
let Some(mut bytes) = buf.borrow_mut().data.data.take() else {
return Err(JsNativeError::typ()
.with_message("cannot transfer a detached buffer")
.into());
};
// 6. If preserveResizability is preserve-resizability and IsResizableArrayBuffer(arrayBuffer)
// is true, then
// a. Let newMaxByteLength be arrayBuffer.[[ArrayBufferMaxByteLength]].
// 7. Else,
// a. Let newMaxByteLength be empty.
let new_max_len = buf.borrow().data.max_byte_len.filter(|_| !TO_FIXED_LENGTH);
// 8. If arrayBuffer.[[ArrayBufferDetachKey]] is not undefined, throw a TypeError exception.
if !buf.borrow().data.detach_key.is_undefined() {
buf.borrow_mut().data.data = Some(bytes);
return Err(JsNativeError::typ()
.with_message("cannot transfer a buffer with a detach key")
.into());
}
// Effectively, the next steps only create a new object for the same vec, so we can skip all
// those steps and just make a single check + trigger the realloc.
// 9. Let newBuffer be ? AllocateArrayBuffer(%ArrayBuffer%, newByteLength, newMaxByteLength).
// 10. Let copyLength be min(newByteLength, arrayBuffer.[[ArrayBufferByteLength]]).
// 11. Let fromBlock be arrayBuffer.[[ArrayBufferData]].
// 12. Let toBlock be newBuffer.[[ArrayBufferData]].
// 13. Perform CopyDataBlockBytes(toBlock, 0, fromBlock, 0, copyLength).
// 14. NOTE: Neither creation of the new Data Block nor copying from the old Data Block are
// observable. Implementations may implement this method as a zero-copy move or a realloc.
// 15. Perform ! DetachArrayBuffer(arrayBuffer).
// 16. Return newBuffer.
if let Some(new_max_len) = new_max_len {
if new_len > new_max_len {
buf.borrow_mut().data.data = Some(bytes);
return Err(JsNativeError::range()
.with_message("`length` cannot be bigger than `maxByteLength`")
.into());
}
// Should only truncate without reallocating.
bytes.resize(new_len as usize, 0);
} else {
bytes.resize(new_len as usize, 0);
// Realloc the vec to fit onto the new exact length.
bytes.shrink_to_fit();
}
let prototype = context
.intrinsics()
.constructors()
.array_buffer()
.prototype();
Ok(JsObject::from_proto_and_data_with_shared_shape(
context.root_shape(),
prototype,
ArrayBuffer {
data: Some(bytes),
max_byte_len: new_max_len,
detach_key: JsValue::undefined(),
},
)
.into())
}
/// `AllocateArrayBuffer ( constructor, byteLength )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-allocatearraybuffer
pub(crate) fn allocate(
constructor: &JsValue,
byte_len: u64,
max_byte_len: Option<u64>,
context: &mut Context,
) -> JsResult<JsObject<ArrayBuffer>> {
// 1. Let slots be « [[ArrayBufferData]], [[ArrayBufferByteLength]], [[ArrayBufferDetachKey]] ».
// 2. If maxByteLength is present and maxByteLength is not empty, let allocatingResizableBuffer be true; otherwise let allocatingResizableBuffer be false.
// 3. If allocatingResizableBuffer is true, then
// a. If byteLength > maxByteLength, throw a RangeError exception.
// b. Append [[ArrayBufferMaxByteLength]] to slots.
if let Some(max_byte_len) = max_byte_len {
if byte_len > max_byte_len {
return Err(JsNativeError::range()
.with_message("`length` cannot be bigger than `maxByteLength`")
.into());
}
}
// 4. Let obj be ? OrdinaryCreateFromConstructor(constructor, "%ArrayBuffer.prototype%", slots).
let prototype = get_prototype_from_constructor(
constructor,
StandardConstructors::array_buffer,
context,
)?;
// 5. Let block be ? CreateByteDataBlock(byteLength).
// Preemptively allocate for `max_byte_len` if possible.
// a. If it is not possible to create a Data Block block consisting of maxByteLength bytes, throw a RangeError exception.
// b. NOTE: Resizable ArrayBuffers are designed to be implementable with in-place growth. Implementations may
// throw if, for example, virtual memory cannot be reserved up front.
let block = create_byte_data_block(byte_len, max_byte_len, context)?;
let obj = JsObject::new(
context.root_shape(),
prototype,
Self {
// 6. Set obj.[[ArrayBufferData]] to block.
// 7. Set obj.[[ArrayBufferByteLength]] to byteLength.
data: Some(block),
// 8. If allocatingResizableBuffer is true, then
// c. Set obj.[[ArrayBufferMaxByteLength]] to maxByteLength.
max_byte_len,
detach_key: JsValue::Undefined,
},
);
// 9. Return obj.
Ok(obj)
}
}
/// Abstract operation [`GetArrayBufferMaxByteLengthOption ( options )`][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-getarraybuffermaxbytelengthoption
fn get_max_byte_len(options: &JsValue, context: &mut Context) -> JsResult<Option<u64>> {
// 1. If options is not an Object, return empty.
let Some(options) = options.as_object() else {
return Ok(None);
};
// 2. Let maxByteLength be ? Get(options, "maxByteLength").
let max_byte_len = options.get(js_string!("maxByteLength"), context)?;
// 3. If maxByteLength is undefined, return empty.
if max_byte_len.is_undefined() {
return Ok(None);
}
// 4. Return ? ToIndex(maxByteLength).
max_byte_len.to_index(context).map(Some)
}
/// `CreateByteDataBlock ( size )` abstract operation.
///
/// The abstract operation `CreateByteDataBlock` takes argument `size` (a non-negative
/// integer). For more information, check the [spec][spec].
///
/// [spec]: https://tc39.es/ecma262/#sec-createbytedatablock
pub(crate) fn create_byte_data_block(
size: u64,
max_buffer_size: Option<u64>,
context: &mut Context,
) -> JsResult<Vec<u8>> {
let alloc_size = max_buffer_size.unwrap_or(size);
assert!(size <= alloc_size);
if alloc_size > context.host_hooks().max_buffer_size(context) {
return Err(JsNativeError::range()
.with_message("cannot allocate a buffer that exceeds the maximum buffer size")
.into());
}
// 1. Let db be a new Data Block value consisting of size bytes. If it is impossible to
// create such a Data Block, throw a RangeError exception.
let alloc_size = alloc_size.try_into().map_err(|e| {
JsNativeError::range().with_message(format!("couldn't allocate the data block: {e}"))
})?;
let mut data_block = Vec::new();
data_block.try_reserve_exact(alloc_size).map_err(|e| {
JsNativeError::range().with_message(format!("couldn't allocate the data block: {e}"))
})?;
// since size <= alloc_size, then `size` must also fit inside a `usize`.
let size = size as usize;
// 2. Set all of the bytes of db to 0.
data_block.resize(size, 0);
// 3. Return db.
Ok(data_block)
}