// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
// Think of Resources as File Descriptors. They are integers that are allocated
// by the privileged side of Deno which refer to various rust objects that need
// to be persisted between various ops. For example, network sockets are
// resources. Resources may or may not correspond to a real operating system
// file descriptor (hence the different name).
use crate::error::bad_resource_id;
use crate::error::custom_error;
use crate::error::not_supported;
use crate::io::BufMutView;
use crate::io::BufView;
use crate::io::WriteOutcome;
use anyhow::Error;
use futures::Future;
use std::any::type_name;
use std::any::Any;
use std::any::TypeId;
use std::borrow::Cow;
use std::collections::BTreeMap;
use std::io::IsTerminal;
use std::iter::Iterator;
use std::pin::Pin;
use std::rc::Rc;
/// Returned by resource read/write/shutdown methods
pub type AsyncResult<T> = Pin<Box<dyn Future<Output = Result<T, Error>>>>;
/// Represents an underlying handle for a platform. On unix, everything is an `fd`. On Windows, everything
/// is a Windows handle except for sockets (which are `SOCKET`s).
#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
#[allow(unused)]
pub enum ResourceHandle {
/// A file handle/descriptor.
Fd(ResourceHandleFd),
/// A socket handle/file descriptor.
Socket(ResourceHandleSocket),
}
#[cfg(unix)]
pub type ResourceHandleFd = std::os::fd::RawFd;
#[cfg(unix)]
pub type ResourceHandleSocket = std::os::fd::RawFd;
#[cfg(windows)]
pub type ResourceHandleFd = std::os::windows::io::RawHandle;
#[cfg(windows)]
pub type ResourceHandleSocket = std::os::windows::io::RawSocket;
impl ResourceHandle {
/// Converts a file-like thing to a [`ResourceHandle`].
#[cfg(windows)]
pub fn from_fd_like(io: &impl std::os::windows::io::AsRawHandle) -> Self {
Self::Fd(io.as_raw_handle())
}
/// Converts a file-like thing to a [`ResourceHandle`].
#[cfg(unix)]
pub fn from_fd_like(io: &impl std::os::unix::io::AsRawFd) -> Self {
Self::Fd(io.as_raw_fd())
}
/// Converts a socket-like thing to a [`ResourceHandle`].
#[cfg(windows)]
pub fn from_socket_like(io: &impl std::os::windows::io::AsRawSocket) -> Self {
Self::Socket(io.as_raw_socket())
}
/// Converts a socket-like thing to a [`ResourceHandle`].
#[cfg(unix)]
pub fn from_socket_like(io: &impl std::os::unix::io::AsRawFd) -> Self {
Self::Socket(io.as_raw_fd())
}
/// Runs a basic validity check on the handle, but cannot fully determine if the handle is valid for use.
pub fn is_valid(&self) -> bool {
#[cfg(windows)]
{
match self {
// NULL or INVALID_HANDLE_VALUE
Self::Fd(handle) => {
!handle.is_null()
&& *handle != -1_isize as std::os::windows::io::RawHandle
}
// INVALID_SOCKET
Self::Socket(socket) => {
*socket != -1_i64 as std::os::windows::io::RawSocket
}
}
}
#[cfg(unix)]
{
match self {
Self::Fd(fd) => *fd >= 0,
Self::Socket(fd) => *fd >= 0,
}
}
}
/// Returns this as a file-descriptor-like handle.
pub fn as_fd_like(&self) -> Option<ResourceHandleFd> {
match self {
Self::Fd(fd) => Some(*fd),
_ => None,
}
}
/// Returns this as a socket-like handle.
pub fn as_socket_like(&self) -> Option<ResourceHandleSocket> {
match self {
Self::Socket(socket) => Some(*socket),
_ => None,
}
}
/// Determines if this handle is a terminal. Analagous to [`std::io::IsTerminal`].
pub fn is_terminal(&self) -> bool {
match self {
Self::Fd(fd) if self.is_valid() => {
#[cfg(windows)]
{
// SAFETY: The resource remains open for the for the duration of borrow_raw
unsafe {
std::os::windows::io::BorrowedHandle::borrow_raw(*fd).is_terminal()
}
}
#[cfg(unix)]
{
// SAFETY: The resource remains open for the for the duration of borrow_raw
unsafe { std::os::fd::BorrowedFd::borrow_raw(*fd).is_terminal() }
}
}
_ => false,
}
}
}
/// Resources are Rust objects that are attached to a [deno_core::JsRuntime].
/// They are identified in JS by a numeric ID (the resource ID, or rid).
/// Resources can be created in ops. Resources can also be retrieved in ops by
/// their rid. Resources are not thread-safe - they can only be accessed from
/// the thread that the JsRuntime lives on.
///
/// Resources are reference counted in Rust. This means that they can be
/// cloned and passed around. When the last reference is dropped, the resource
/// is automatically closed. As long as the resource exists in the resource
/// table, the reference count is at least 1.
///
/// ### Readable
///
/// Readable resources are resources that can have data read from. Examples of
/// this are files, sockets, or HTTP streams.
///
/// Readables can be read from from either JS or Rust. In JS one can use
/// `Deno.core.read()` to read from a single chunk of data from a readable. In
/// Rust one can directly call `read()` or `read_byob()`. The Rust side code is
/// used to implement ops like `op_slice`.
///
/// A distinction can be made between readables that produce chunks of data
/// themselves (they allocate the chunks), and readables that fill up
/// bring-your-own-buffers (BYOBs). The former is often the case for framed
/// protocols like HTTP, while the latter is often the case for kernel backed
/// resources like files and sockets.
///
/// All readables must implement `read()`. If resources can support an optimized
/// path for BYOBs, they should also implement `read_byob()`. For kernel backed
/// resources it often makes sense to implement `read_byob()` first, and then
/// implement `read()` as an operation that allocates a new chunk with
/// `len == limit`, then calls `read_byob()`, and then returns a chunk sliced to
/// the number of bytes read. Kernel backed resources can use the
/// [deno_core::impl_readable_byob] macro to implement optimized `read_byob()`
/// and `read()` implementations from a single `Self::read()` method.
///
/// ### Writable
///
/// Writable resources are resources that can have data written to. Examples of
/// this are files, sockets, or HTTP streams.
///
/// Writables can be written to from either JS or Rust. In JS one can use
/// `Deno.core.write()` to write to a single chunk of data to a writable. In
/// Rust one can directly call `write()`. The latter is used to implement ops
/// like `op_slice`.
pub trait Resource: Any + 'static {
/// Returns a string representation of the resource which is made available
/// to JavaScript code through `op_resources`. The default implementation
/// returns the Rust type name, but specific resource types may override this
/// trait method.
fn name(&self) -> Cow<str> {
type_name::<Self>().into()
}
/// Read a single chunk of data from the resource. This operation returns a
/// `BufView` that represents the data that was read. If a zero length buffer
/// is returned, it indicates that the resource has reached EOF.
///
/// If this method is not implemented, the default implementation will error
/// with a "not supported" error.
///
/// If a readable can provide an optimized path for BYOBs, it should also
/// implement `read_byob()`.
fn read(self: Rc<Self>, limit: usize) -> AsyncResult<BufView> {
_ = limit;
Box::pin(futures::future::err(not_supported()))
}
/// Read a single chunk of data from the resource into the provided `BufMutView`.
///
/// This operation returns the number of bytes read. If zero bytes are read,
/// it indicates that the resource has reached EOF.
///
/// If this method is not implemented explicitly, the default implementation
/// will call `read()` and then copy the data into the provided buffer. For
/// readable resources that can provide an optimized path for BYOBs, it is
/// strongly recommended to override this method.
fn read_byob(
self: Rc<Self>,
mut buf: BufMutView,
) -> AsyncResult<(usize, BufMutView)> {
Box::pin(async move {
let read = self.read(buf.len()).await?;
let nread = read.len();
buf[..nread].copy_from_slice(&read);
Ok((nread, buf))
})
}
/// Write an error state to this resource, if the resource supports it.
fn write_error(self: Rc<Self>, _error: Error) -> AsyncResult<()> {
Box::pin(futures::future::err(not_supported()))
}
/// Write a single chunk of data to the resource. The operation may not be
/// able to write the entire chunk, in which case it should return the number
/// of bytes written. Additionally it should return the `BufView` that was
/// passed in.
///
/// If this method is not implemented, the default implementation will error
/// with a "not supported" error.
fn write(self: Rc<Self>, buf: BufView) -> AsyncResult<WriteOutcome> {
_ = buf;
Box::pin(futures::future::err(not_supported()))
}
/// Write an entire chunk of data to the resource. Unlike `write()`, this will
/// ensure the entire chunk is written. If the operation is not able to write
/// the entire chunk, an error is to be returned.
///
/// By default this method will call `write()` repeatedly until the entire
/// chunk is written. Resources that can write the entire chunk in a single
/// operation using an optimized path should override this method.
fn write_all(self: Rc<Self>, view: BufView) -> AsyncResult<()> {
Box::pin(async move {
let mut view = view;
let this = self;
while !view.is_empty() {
let resp = this.clone().write(view).await?;
match resp {
WriteOutcome::Partial {
nwritten,
view: new_view,
} => {
view = new_view;
view.advance_cursor(nwritten);
}
WriteOutcome::Full { .. } => break,
}
}
Ok(())
})
}
/// The same as [`read_byob()`][Resource::read_byob], but synchronous.
fn read_byob_sync(self: Rc<Self>, data: &mut [u8]) -> Result<usize, Error> {
_ = data;
Err(not_supported())
}
/// The same as [`write()`][Resource::write], but synchronous.
fn write_sync(self: Rc<Self>, data: &[u8]) -> Result<usize, Error> {
_ = data;
Err(not_supported())
}
/// The shutdown method can be used to asynchronously close the resource. It
/// is not automatically called when the resource is dropped or closed.
///
/// If this method is not implemented, the default implementation will error
/// with a "not supported" error.
fn shutdown(self: Rc<Self>) -> AsyncResult<()> {
Box::pin(futures::future::err(not_supported()))
}
/// Resources may implement the `close()` trait method if they need to do
/// resource specific clean-ups, such as cancelling pending futures, after a
/// resource has been removed from the resource table.
fn close(self: Rc<Self>) {}
/// Resources backed by a file descriptor or socket handle can let ops know
/// to allow for low-level optimizations.
fn backing_handle(self: Rc<Self>) -> Option<ResourceHandle> {
#[allow(deprecated)]
self.backing_fd().map(ResourceHandle::Fd)
}
/// Resources backed by a file descriptor can let ops know to allow for
/// low-level optimizations.
#[deprecated = "Use backing_handle"]
fn backing_fd(self: Rc<Self>) -> Option<ResourceHandleFd> {
None
}
fn size_hint(&self) -> (u64, Option<u64>) {
(0, None)
}
}
impl dyn Resource {
#[inline(always)]
fn is<T: Resource>(&self) -> bool {
self.type_id() == TypeId::of::<T>()
}
#[inline(always)]
#[allow(clippy::needless_lifetimes)]
pub fn downcast_rc<'a, T: Resource>(self: &'a Rc<Self>) -> Option<&'a Rc<T>> {
if self.is::<T>() {
let ptr = self as *const Rc<_> as *const Rc<T>;
// TODO(piscisaureus): safety comment
#[allow(clippy::undocumented_unsafe_blocks)]
Some(unsafe { &*ptr })
} else {
None
}
}
}
/// A `ResourceId` is an integer value referencing a resource. It could be
/// considered to be the Deno equivalent of a `file descriptor` in POSIX like
/// operating systems. Elsewhere in the code base it is commonly abbreviated
/// to `rid`.
// TODO: use `u64` instead?
pub type ResourceId = u32;
/// Map-like data structure storing Deno's resources (equivalent to file
/// descriptors).
///
/// Provides basic methods for element access. A resource can be of any type.
/// Different types of resources can be stored in the same map, and provided
/// with a name for description.
///
/// Each resource is identified through a _resource ID (rid)_, which acts as
/// the key in the map.
#[derive(Default)]
pub struct ResourceTable {
index: BTreeMap<ResourceId, Rc<dyn Resource>>,
next_rid: ResourceId,
}
impl ResourceTable {
/// Returns the number of resources currently active in the resource table.
/// Resources taken from the table do not contribute to this count.
pub fn len(&self) -> usize {
self.index.len()
}
/// Returns whether this table is empty.
pub fn is_empty(&self) -> bool {
self.index.is_empty()
}
/// Inserts resource into the resource table, which takes ownership of it.
///
/// The resource type is erased at runtime and must be statically known
/// when retrieving it through `get()`.
///
/// Returns a unique resource ID, which acts as a key for this resource.
pub fn add<T: Resource>(&mut self, resource: T) -> ResourceId {
self.add_rc(Rc::new(resource))
}
/// Inserts a `Rc`-wrapped resource into the resource table.
///
/// The resource type is erased at runtime and must be statically known
/// when retrieving it through `get()`.
///
/// Returns a unique resource ID, which acts as a key for this resource.
pub fn add_rc<T: Resource>(&mut self, resource: Rc<T>) -> ResourceId {
let resource = resource as Rc<dyn Resource>;
self.add_rc_dyn(resource)
}
pub fn add_rc_dyn(&mut self, resource: Rc<dyn Resource>) -> ResourceId {
let rid = self.next_rid;
let removed_resource = self.index.insert(rid, resource);
assert!(removed_resource.is_none());
self.next_rid += 1;
rid
}
/// Returns true if any resource with the given `rid` exists.
pub fn has(&self, rid: ResourceId) -> bool {
self.index.contains_key(&rid)
}
/// Returns a reference counted pointer to the resource of type `T` with the
/// given `rid`. If `rid` is not present or has a type different than `T`,
/// this function returns `None`.
pub fn get<T: Resource>(&self, rid: ResourceId) -> Result<Rc<T>, Error> {
self
.index
.get(&rid)
.and_then(|rc| rc.downcast_rc::<T>())
.map(Clone::clone)
.ok_or_else(bad_resource_id)
}
pub fn get_any(&self, rid: ResourceId) -> Result<Rc<dyn Resource>, Error> {
self
.index
.get(&rid)
.map(Clone::clone)
.ok_or_else(bad_resource_id)
}
/// Replaces a resource with a new resource.
///
/// Panics if the resource does not exist.
pub fn replace<T: Resource>(&mut self, rid: ResourceId, resource: T) {
let result = self
.index
.insert(rid, Rc::new(resource) as Rc<dyn Resource>);
assert!(result.is_some());
}
/// Removes a resource of type `T` from the resource table and returns it.
/// If a resource with the given `rid` exists but its type does not match `T`,
/// it is not removed from the resource table. Note that the resource's
/// `close()` method is *not* called.
///
/// Also note that there might be a case where
/// the returned `Rc<T>` is referenced by other variables. That is, we cannot
/// assume that `Rc::strong_count(&returned_rc)` is always equal to 1 on success.
/// In particular, be really careful when you want to extract the inner value of
/// type `T` from `Rc<T>`.
pub fn take<T: Resource>(&mut self, rid: ResourceId) -> Result<Rc<T>, Error> {
let resource = self.get::<T>(rid)?;
self.index.remove(&rid);
Ok(resource)
}
/// Removes a resource from the resource table and returns it. Note that the
/// resource's `close()` method is *not* called.
///
/// Also note that there might be a
/// case where the returned `Rc<T>` is referenced by other variables. That is,
/// we cannot assume that `Rc::strong_count(&returned_rc)` is always equal to 1
/// on success. In particular, be really careful when you want to extract the
/// inner value of type `T` from `Rc<T>`.
pub fn take_any(
&mut self,
rid: ResourceId,
) -> Result<Rc<dyn Resource>, Error> {
self.index.remove(&rid).ok_or_else(bad_resource_id)
}
/// Removes the resource with the given `rid` from the resource table. If the
/// only reference to this resource existed in the resource table, this will
/// cause the resource to be dropped. However, since resources are reference
/// counted, therefore pending ops are not automatically cancelled. A resource
/// may implement the `close()` method to perform clean-ups such as canceling
/// ops.
#[deprecated = "This method may deadlock. Use take() and close() instead."]
pub fn close(&mut self, rid: ResourceId) -> Result<(), Error> {
self
.index
.remove(&rid)
.ok_or_else(bad_resource_id)
.map(|resource| resource.close())
}
/// Returns an iterator that yields a `(id, name)` pair for every resource
/// that's currently in the resource table. This can be used for debugging
/// purposes or to implement the `op_resources` op. Note that the order in
/// which items appear is not specified.
///
/// # Example
///
/// ```
/// # use deno_core::ResourceTable;
/// # let resource_table = ResourceTable::default();
/// let resource_names = resource_table.names().collect::<Vec<_>>();
/// ```
pub fn names(&self) -> impl Iterator<Item = (ResourceId, Cow<str>)> {
self
.index
.iter()
.map(|(&id, resource)| (id, resource.name()))
}
/// Retrieves the [`ResourceHandleFd`] for a given resource, for potential optimization
/// purposes within ops.
pub fn get_fd(&self, rid: ResourceId) -> Result<ResourceHandleFd, Error> {
let Some(handle) = self.get_any(rid)?.backing_handle() else {
return Err(bad_resource_id());
};
let Some(fd) = handle.as_fd_like() else {
return Err(bad_resource_id());
};
if !handle.is_valid() {
return Err(custom_error("ReferenceError", "null or invalid handle"));
}
Ok(fd)
}
/// Retrieves the [`ResourceHandleSocket`] for a given resource, for potential optimization
/// purposes within ops.
pub fn get_socket(
&self,
rid: ResourceId,
) -> Result<ResourceHandleSocket, Error> {
let Some(handle) = self.get_any(rid)?.backing_handle() else {
return Err(bad_resource_id());
};
let Some(socket) = handle.as_socket_like() else {
return Err(bad_resource_id());
};
if !handle.is_valid() {
return Err(custom_error("ReferenceError", "null or invalid handle"));
}
Ok(socket)
}
/// Retrieves the [`ResourceHandle`] for a given resource, for potential optimization
/// purposes within ops.
pub fn get_handle(
&self,
rid: ResourceId,
) -> ::std::result::Result<ResourceHandle, ::anyhow::Error> {
let Some(handle) = self.get_any(rid)?.backing_handle() else {
return Err(bad_resource_id());
};
if !handle.is_valid() {
return Err(custom_error("ReferenceError", "null or invalid handle"));
}
Ok(handle)
}
}
#[macro_export]
macro_rules! impl_readable_byob {
() => {
fn read(
self: ::std::rc::Rc<Self>,
limit: ::core::primitive::usize,
) -> AsyncResult<$crate::BufView> {
::std::boxed::Box::pin(async move {
let mut vec = ::std::vec![0; limit];
let nread = self.read(&mut vec).await?;
if nread != vec.len() {
vec.truncate(nread);
}
let view = $crate::BufView::from(vec);
::std::result::Result::Ok(view)
})
}
fn read_byob(
self: ::std::rc::Rc<Self>,
mut buf: $crate::BufMutView,
) -> AsyncResult<(::core::primitive::usize, $crate::BufMutView)> {
::std::boxed::Box::pin(async move {
let nread = self.read(buf.as_mut()).await?;
::std::result::Result::Ok((nread, buf))
})
}
};
}
#[macro_export]
macro_rules! impl_writable {
(__write) => {
fn write(
self: ::std::rc::Rc<Self>,
view: $crate::BufView,
) -> $crate::AsyncResult<$crate::WriteOutcome> {
::std::boxed::Box::pin(async move {
let nwritten = self.write(&view).await?;
::std::result::Result::Ok($crate::WriteOutcome::Partial {
nwritten,
view,
})
})
}
};
(__write_all) => {
fn write_all(
self: ::std::rc::Rc<Self>,
view: $crate::BufView,
) -> $crate::AsyncResult<()> {
::std::boxed::Box::pin(async move {
self.write_all(&view).await?;
::std::result::Result::Ok(())
})
}
};
() => {
$crate::impl_writable!(__write);
};
(with_all) => {
$crate::impl_writable!(__write);
$crate::impl_writable!(__write_all);
};
}