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denoland-deno/ext/ffi/callback.rs
Divy Srivastava a2db70a8d0
refactor(ext/ffi): split into multiple parts (#16950)
- [x] `dlfcn.rs` - `dlopen()`-related code.
- [x] `turbocall.rs` - Call trampoline JIT compiler. 
- [x] `repr.rs` - Pointer representation. Home of the UnsafePointerView
ops.
- [x] `symbol.rs` - Function symbol related code.
- [x] `callback.rs` - Home of `Deno.UnsafeCallback` ops.
- [x] `ir.rs` - Intermediate representation for values. Home of the
`NativeValue` type.
- [x] `call.rs` - Generic call ops. Home to everything related to
calling FFI symbols.
- [x] `static.rs` - static symbol support

I find easier to work with this setup, I eventually want to expand
TurboCall to unroll type conversion loop in generic calls, generate code
for individual symbols (lazy function pointers), etc.
2022-12-12 14:14:20 +00:00

562 lines
18 KiB
Rust

// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
use crate::check_unstable;
use crate::symbol::NativeType;
use crate::FfiPermissions;
use crate::FfiState;
use crate::ForeignFunction;
use crate::PendingFfiAsyncWork;
use crate::LOCAL_ISOLATE_POINTER;
use crate::MAX_SAFE_INTEGER;
use crate::MIN_SAFE_INTEGER;
use deno_core::error::AnyError;
use deno_core::futures::channel::mpsc;
use deno_core::op;
use deno_core::serde_v8;
use deno_core::v8;
use deno_core::CancelFuture;
use deno_core::CancelHandle;
use deno_core::OpState;
use deno_core::Resource;
use deno_core::ResourceId;
use libffi::middle::Cif;
use serde::Deserialize;
use std::borrow::Cow;
use std::cell::RefCell;
use std::ffi::c_void;
use std::future::Future;
use std::future::IntoFuture;
use std::pin::Pin;
use std::ptr;
use std::ptr::NonNull;
use std::rc::Rc;
use std::sync::mpsc::sync_channel;
use std::task::Poll;
use std::task::Waker;
#[derive(Clone)]
pub struct PtrSymbol {
pub cif: libffi::middle::Cif,
pub ptr: libffi::middle::CodePtr,
}
impl PtrSymbol {
pub fn new(fn_ptr: usize, def: &ForeignFunction) -> Self {
let ptr = libffi::middle::CodePtr::from_ptr(fn_ptr as _);
let cif = libffi::middle::Cif::new(
def
.parameters
.clone()
.into_iter()
.map(libffi::middle::Type::from),
def.result.into(),
);
Self { cif, ptr }
}
}
#[allow(clippy::non_send_fields_in_send_ty)]
// SAFETY: unsafe trait must have unsafe implementation
unsafe impl Send for PtrSymbol {}
// SAFETY: unsafe trait must have unsafe implementation
unsafe impl Sync for PtrSymbol {}
struct UnsafeCallbackResource {
cancel: Rc<CancelHandle>,
// Closure is never directly touched, but it keeps the C callback alive
// until `close()` method is called.
#[allow(dead_code)]
closure: libffi::middle::Closure<'static>,
info: *mut CallbackInfo,
}
impl Resource for UnsafeCallbackResource {
fn name(&self) -> Cow<str> {
"unsafecallback".into()
}
fn close(self: Rc<Self>) {
self.cancel.cancel();
// SAFETY: This drops the closure and the callback info associated with it.
// Any retained function pointers to the closure become dangling pointers.
// It is up to the user to know that it is safe to call the `close()` on the
// UnsafeCallback instance.
unsafe {
let info = Box::from_raw(self.info);
let isolate = info.isolate.as_mut().unwrap();
let _ = v8::Global::from_raw(isolate, info.callback);
let _ = v8::Global::from_raw(isolate, info.context);
}
}
}
struct CallbackInfo {
pub parameters: Vec<NativeType>,
pub result: NativeType,
pub async_work_sender: mpsc::UnboundedSender<PendingFfiAsyncWork>,
pub callback: NonNull<v8::Function>,
pub context: NonNull<v8::Context>,
pub isolate: *mut v8::Isolate,
pub waker: Option<Waker>,
}
impl Future for CallbackInfo {
type Output = ();
fn poll(
mut self: Pin<&mut Self>,
cx: &mut std::task::Context<'_>,
) -> std::task::Poll<Self::Output> {
// Always replace the waker to make sure it's bound to the proper Future.
self.waker.replace(cx.waker().clone());
// The future for the CallbackInfo never resolves: It can only be canceled.
Poll::Pending
}
}
unsafe extern "C" fn deno_ffi_callback(
_cif: &libffi::low::ffi_cif,
result: &mut c_void,
args: *const *const c_void,
info: &CallbackInfo,
) {
LOCAL_ISOLATE_POINTER.with(|s| {
if ptr::eq(*s.borrow(), info.isolate) {
// Own isolate thread, okay to call directly
do_ffi_callback(info, result, args);
} else {
let async_work_sender = &info.async_work_sender;
// SAFETY: Safe as this function blocks until `do_ffi_callback` completes and a response message is received.
let result: &'static mut c_void = std::mem::transmute(result);
let info: &'static CallbackInfo = std::mem::transmute(info);
let (response_sender, response_receiver) = sync_channel::<()>(0);
let fut = Box::new(move || {
do_ffi_callback(info, result, args);
response_sender.send(()).unwrap();
});
async_work_sender.unbounded_send(fut).unwrap();
if let Some(waker) = info.waker.as_ref() {
// Make sure event loop wakes up to receive our message before we start waiting for a response.
waker.wake_by_ref();
}
response_receiver.recv().unwrap();
}
});
}
unsafe fn do_ffi_callback(
info: &CallbackInfo,
result: &mut c_void,
args: *const *const c_void,
) {
let callback: NonNull<v8::Function> = info.callback;
let context: NonNull<v8::Context> = info.context;
let isolate: *mut v8::Isolate = info.isolate;
let isolate = &mut *isolate;
let callback = v8::Global::from_raw(isolate, callback);
let context = std::mem::transmute::<
NonNull<v8::Context>,
v8::Local<v8::Context>,
>(context);
// Call from main thread. If this callback is being triggered due to a
// function call coming from Deno itself, then this callback will build
// ontop of that stack.
// If this callback is being triggered outside of Deno (for example from a
// signal handler) then this will either create an empty new stack if
// Deno currently has nothing running and is waiting for promises to resolve,
// or will (very incorrectly) build ontop of whatever stack exists.
// The callback will even be called through from a `while (true)` liveloop, but
// it somehow cannot change the values that the loop sees, even if they both
// refer the same `let bool_value`.
let mut cb_scope = v8::CallbackScope::new(context);
let scope = &mut v8::HandleScope::new(&mut cb_scope);
let func = callback.open(scope);
let result = result as *mut c_void;
let vals: &[*const c_void] =
std::slice::from_raw_parts(args, info.parameters.len() as usize);
let mut params: Vec<v8::Local<v8::Value>> = vec![];
for (native_type, val) in info.parameters.iter().zip(vals) {
let value: v8::Local<v8::Value> = match native_type {
NativeType::Bool => {
let value = *((*val) as *const bool);
v8::Boolean::new(scope, value).into()
}
NativeType::F32 => {
let value = *((*val) as *const f32);
v8::Number::new(scope, value as f64).into()
}
NativeType::F64 => {
let value = *((*val) as *const f64);
v8::Number::new(scope, value).into()
}
NativeType::I8 => {
let value = *((*val) as *const i8);
v8::Integer::new(scope, value as i32).into()
}
NativeType::U8 => {
let value = *((*val) as *const u8);
v8::Integer::new_from_unsigned(scope, value as u32).into()
}
NativeType::I16 => {
let value = *((*val) as *const i16);
v8::Integer::new(scope, value as i32).into()
}
NativeType::U16 => {
let value = *((*val) as *const u16);
v8::Integer::new_from_unsigned(scope, value as u32).into()
}
NativeType::I32 => {
let value = *((*val) as *const i32);
v8::Integer::new(scope, value).into()
}
NativeType::U32 => {
let value = *((*val) as *const u32);
v8::Integer::new_from_unsigned(scope, value).into()
}
NativeType::I64 | NativeType::ISize => {
let result = *((*val) as *const i64);
if result > MAX_SAFE_INTEGER as i64 || result < MIN_SAFE_INTEGER as i64
{
v8::BigInt::new_from_i64(scope, result).into()
} else {
v8::Number::new(scope, result as f64).into()
}
}
NativeType::U64 | NativeType::USize => {
let result = *((*val) as *const u64);
if result > MAX_SAFE_INTEGER as u64 {
v8::BigInt::new_from_u64(scope, result).into()
} else {
v8::Number::new(scope, result as f64).into()
}
}
NativeType::Pointer | NativeType::Buffer | NativeType::Function => {
let result = *((*val) as *const usize);
if result > MAX_SAFE_INTEGER as usize {
v8::BigInt::new_from_u64(scope, result as u64).into()
} else {
v8::Number::new(scope, result as f64).into()
}
}
NativeType::Void => unreachable!(),
};
params.push(value);
}
let recv = v8::undefined(scope);
let call_result = func.call(scope, recv.into(), &params);
std::mem::forget(callback);
if call_result.is_none() {
// JS function threw an exception. Set the return value to zero and return.
// The exception continue propagating up the call chain when the event loop
// resumes.
match info.result {
NativeType::Bool => {
*(result as *mut bool) = false;
}
NativeType::U32 | NativeType::I32 => {
// zero is equal for signed and unsigned alike
*(result as *mut u32) = 0;
}
NativeType::F32 => {
*(result as *mut f32) = 0.0;
}
NativeType::F64 => {
*(result as *mut f64) = 0.0;
}
NativeType::U8 | NativeType::I8 => {
// zero is equal for signed and unsigned alike
*(result as *mut u8) = 0;
}
NativeType::U16 | NativeType::I16 => {
// zero is equal for signed and unsigned alike
*(result as *mut u16) = 0;
}
NativeType::Pointer
| NativeType::Buffer
| NativeType::Function
| NativeType::U64
| NativeType::I64 => {
*(result as *mut usize) = 0;
}
NativeType::Void => {
// nop
}
_ => {
unreachable!();
}
};
return;
}
let value = call_result.unwrap();
match info.result {
NativeType::Bool => {
let value = if let Ok(value) = v8::Local::<v8::Boolean>::try_from(value) {
value.is_true()
} else {
value.boolean_value(scope)
};
*(result as *mut bool) = value;
}
NativeType::I32 => {
let value = if let Ok(value) = v8::Local::<v8::Integer>::try_from(value) {
value.value() as i32
} else {
// Fallthrough, probably UB.
value
.int32_value(scope)
.expect("Unable to deserialize result parameter.") as i32
};
*(result as *mut i32) = value;
}
NativeType::F32 => {
let value = if let Ok(value) = v8::Local::<v8::Number>::try_from(value) {
value.value() as f32
} else {
// Fallthrough, probably UB.
value
.number_value(scope)
.expect("Unable to deserialize result parameter.") as f32
};
*(result as *mut f32) = value;
}
NativeType::F64 => {
let value = if let Ok(value) = v8::Local::<v8::Number>::try_from(value) {
value.value()
} else {
// Fallthrough, probably UB.
value
.number_value(scope)
.expect("Unable to deserialize result parameter.")
};
*(result as *mut f64) = value;
}
NativeType::Pointer | NativeType::Buffer | NativeType::Function => {
let pointer = if let Ok(value) =
v8::Local::<v8::ArrayBufferView>::try_from(value)
{
let byte_offset = value.byte_offset();
let backing_store = value
.buffer(scope)
.expect("Unable to deserialize result parameter.")
.get_backing_store();
&backing_store[byte_offset..] as *const _ as *const u8
} else if let Ok(value) = v8::Local::<v8::BigInt>::try_from(value) {
value.u64_value().0 as usize as *const u8
} else if let Ok(value) = v8::Local::<v8::ArrayBuffer>::try_from(value) {
let backing_store = value.get_backing_store();
&backing_store[..] as *const _ as *const u8
} else if let Ok(value) = v8::Local::<v8::Integer>::try_from(value) {
value.value() as usize as *const u8
} else if value.is_null() {
ptr::null()
} else {
// Fallthrough: Probably someone returned a number but this could
// also be eg. a string. This is essentially UB.
value
.integer_value(scope)
.expect("Unable to deserialize result parameter.") as usize
as *const u8
};
*(result as *mut *const u8) = pointer;
}
NativeType::I8 => {
let value = if let Ok(value) = v8::Local::<v8::Integer>::try_from(value) {
value.value() as i8
} else {
// Fallthrough, essentially UB.
value
.int32_value(scope)
.expect("Unable to deserialize result parameter.") as i8
};
*(result as *mut i8) = value;
}
NativeType::U8 => {
let value = if let Ok(value) = v8::Local::<v8::Integer>::try_from(value) {
value.value() as u8
} else {
// Fallthrough, essentially UB.
value
.uint32_value(scope)
.expect("Unable to deserialize result parameter.") as u8
};
*(result as *mut u8) = value;
}
NativeType::I16 => {
let value = if let Ok(value) = v8::Local::<v8::Integer>::try_from(value) {
value.value() as i16
} else {
// Fallthrough, essentially UB.
value
.int32_value(scope)
.expect("Unable to deserialize result parameter.") as i16
};
*(result as *mut i16) = value;
}
NativeType::U16 => {
let value = if let Ok(value) = v8::Local::<v8::Integer>::try_from(value) {
value.value() as u16
} else {
// Fallthrough, essentially UB.
value
.uint32_value(scope)
.expect("Unable to deserialize result parameter.") as u16
};
*(result as *mut u16) = value;
}
NativeType::U32 => {
let value = if let Ok(value) = v8::Local::<v8::Integer>::try_from(value) {
value.value() as u32
} else {
// Fallthrough, essentially UB.
value
.uint32_value(scope)
.expect("Unable to deserialize result parameter.")
};
*(result as *mut u32) = value;
}
NativeType::I64 => {
if let Ok(value) = v8::Local::<v8::BigInt>::try_from(value) {
*(result as *mut i64) = value.i64_value().0;
} else if let Ok(value) = v8::Local::<v8::Integer>::try_from(value) {
*(result as *mut i64) = value.value();
} else {
*(result as *mut i64) = value
.integer_value(scope)
.expect("Unable to deserialize result parameter.")
as i64;
}
}
NativeType::U64 => {
if let Ok(value) = v8::Local::<v8::BigInt>::try_from(value) {
*(result as *mut u64) = value.u64_value().0;
} else if let Ok(value) = v8::Local::<v8::Integer>::try_from(value) {
*(result as *mut u64) = value.value() as u64;
} else {
*(result as *mut u64) = value
.integer_value(scope)
.expect("Unable to deserialize result parameter.")
as u64;
}
}
NativeType::Void => {
// nop
}
_ => {
unreachable!();
}
};
}
#[op]
pub fn op_ffi_unsafe_callback_ref(
state: Rc<RefCell<OpState>>,
rid: ResourceId,
) -> Result<impl Future<Output = Result<(), AnyError>>, AnyError> {
let state = state.borrow();
let callback_resource =
state.resource_table.get::<UnsafeCallbackResource>(rid)?;
Ok(async move {
let info: &mut CallbackInfo =
// SAFETY: CallbackInfo pointer stays valid as long as the resource is still alive.
unsafe { callback_resource.info.as_mut().unwrap() };
// Ignore cancellation rejection
let _ = info
.into_future()
.or_cancel(callback_resource.cancel.clone())
.await;
Ok(())
})
}
#[op(fast)]
pub fn op_ffi_unsafe_callback_unref(
state: &mut deno_core::OpState,
rid: u32,
) -> Result<(), AnyError> {
state
.resource_table
.get::<UnsafeCallbackResource>(rid)?
.cancel
.cancel();
Ok(())
}
#[derive(Deserialize)]
pub struct RegisterCallbackArgs {
parameters: Vec<NativeType>,
result: NativeType,
}
#[op(v8)]
pub fn op_ffi_unsafe_callback_create<FP, 'scope>(
state: &mut deno_core::OpState,
scope: &mut v8::HandleScope<'scope>,
args: RegisterCallbackArgs,
cb: serde_v8::Value<'scope>,
) -> Result<serde_v8::Value<'scope>, AnyError>
where
FP: FfiPermissions + 'static,
{
check_unstable(state, "Deno.UnsafeCallback");
let permissions = state.borrow_mut::<FP>();
permissions.check(None)?;
let v8_value = cb.v8_value;
let cb = v8::Local::<v8::Function>::try_from(v8_value)?;
let isolate: *mut v8::Isolate = &mut *scope as &mut v8::Isolate;
LOCAL_ISOLATE_POINTER.with(|s| {
if s.borrow().is_null() {
s.replace(isolate);
}
});
let async_work_sender =
state.borrow_mut::<FfiState>().async_work_sender.clone();
let callback = v8::Global::new(scope, cb).into_raw();
let current_context = scope.get_current_context();
let context = v8::Global::new(scope, current_context).into_raw();
let info: *mut CallbackInfo = Box::leak(Box::new(CallbackInfo {
parameters: args.parameters.clone(),
result: args.result,
async_work_sender,
callback,
context,
isolate,
waker: None,
}));
let cif = Cif::new(
args.parameters.into_iter().map(libffi::middle::Type::from),
libffi::middle::Type::from(args.result),
);
// SAFETY: CallbackInfo is leaked, is not null and stays valid as long as the callback exists.
let closure = libffi::middle::Closure::new(cif, deno_ffi_callback, unsafe {
info.as_ref().unwrap()
});
let ptr = *closure.code_ptr() as usize;
let resource = UnsafeCallbackResource {
cancel: CancelHandle::new_rc(),
closure,
info,
};
let rid = state.resource_table.add(resource);
let rid_local = v8::Integer::new_from_unsigned(scope, rid);
let ptr_local: v8::Local<v8::Value> = if ptr > MAX_SAFE_INTEGER as usize {
v8::BigInt::new_from_u64(scope, ptr as u64).into()
} else {
v8::Number::new(scope, ptr as f64).into()
};
let array = v8::Array::new(scope, 2);
array.set_index(scope, 0, rid_local.into());
array.set_index(scope, 1, ptr_local);
let array_value: v8::Local<v8::Value> = array.into();
Ok(array_value.into())
}