1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621
use crate::callable::{NativeCallable, WasmtimeFn, WrappedCallable}; use crate::{Callable, FuncType, Store, Trap, Val, ValType}; use anyhow::{ensure, Context as _}; use std::fmt; use std::mem; use std::panic::{self, AssertUnwindSafe}; use std::ptr; use std::rc::Rc; use wasmtime_runtime::{InstanceHandle, VMContext, VMFunctionBody}; /// A WebAssembly function which can be called. /// /// This type can represent a number of callable items, such as: /// /// * An exported function from a WebAssembly module. /// * A user-defined function used to satisfy an import. /// /// These types of callable items are all wrapped up in this `Func` and can be /// used to both instantiate an [`Instance`](crate::Instance) as well as be /// extracted from an [`Instance`](crate::Instance). /// /// # `Func` and `Clone` /// /// Functions are internally reference counted so you can `clone` a `Func`. The /// cloning process only performs a shallow clone, so two cloned `Func` /// instances are equivalent in their functionality. #[derive(Clone)] pub struct Func { _store: Store, callable: Rc<dyn WrappedCallable + 'static>, ty: FuncType, } macro_rules! wrappers { ($( $(#[$doc:meta])* ($name:ident $(,$args:ident)*) )*) => ($( $(#[$doc])* pub fn $name<F, $($args,)* R>(store: &Store, func: F) -> Func where F: Fn($($args),*) -> R + 'static, $($args: WasmTy,)* R: WasmRet, { #[allow(non_snake_case)] unsafe extern "C" fn shim<F, $($args,)* R>( vmctx: *mut VMContext, _caller_vmctx: *mut VMContext, $($args: $args::Abi,)* ) -> R::Abi where F: Fn($($args),*) -> R + 'static, $($args: WasmTy,)* R: WasmRet, { let ret = { let instance = InstanceHandle::from_vmctx(vmctx); let func = instance.host_state().downcast_ref::<F>().expect("state"); panic::catch_unwind(AssertUnwindSafe(|| { func($($args::from_abi(_caller_vmctx, $args)),*) })) }; match ret { Ok(ret) => ret.into_abi(), Err(panic) => wasmtime_runtime::resume_panic(panic), } } let mut _args = Vec::new(); $($args::push(&mut _args);)* let mut ret = Vec::new(); R::push(&mut ret); let ty = FuncType::new(_args.into(), ret.into()); unsafe { let (instance, export) = crate::trampoline::generate_raw_func_export( &ty, std::slice::from_raw_parts_mut( shim::<F, $($args,)* R> as *mut _, 0, ), store, Box::new(func), ) .expect("failed to generate export"); let callable = Rc::new(WasmtimeFn::new(store, instance, export)); Func::from_wrapped(store, ty, callable) } } )*) } macro_rules! getters { ($( $(#[$doc:meta])* ($name:ident $(,$args:ident)*) )*) => ($( $(#[$doc])* #[allow(non_snake_case)] pub fn $name<$($args,)* R>(&self) -> anyhow::Result<impl Fn($($args,)*) -> Result<R, Trap>> where $($args: WasmTy,)* R: WasmTy, { // Verify all the paramers match the expected parameters, and that // there are no extra parameters... let mut params = self.ty().params().iter().cloned(); let n = 0; $( let n = n + 1; $args::matches(&mut params) .with_context(|| format!("Type mismatch in argument {}", n))?; )* ensure!(params.next().is_none(), "Type mismatch: too many arguments (expected {})", n); // ... then do the same for the results... let mut results = self.ty().results().iter().cloned(); R::matches(&mut results) .context("Type mismatch in return type")?; ensure!(results.next().is_none(), "Type mismatch: too many return values (expected 1)"); // ... and then once we've passed the typechecks we can hand out our // object since our `transmute` below should be safe! let (address, vmctx) = match self.wasmtime_export() { wasmtime_runtime::Export::Function { address, vmctx, signature: _} => { (*address, *vmctx) } _ => panic!("expected function export"), }; Ok(move |$($args: $args),*| -> Result<R, Trap> { unsafe { let f = mem::transmute::< *const VMFunctionBody, unsafe extern "C" fn( *mut VMContext, *mut VMContext, $($args::Abi,)* ) -> R::Abi, >(address); let mut ret = None; $(let $args = $args.into_abi();)* wasmtime_runtime::catch_traps(vmctx, || { ret = Some(f(vmctx, ptr::null_mut(), $($args,)*)); }).map_err(Trap::from_jit)?; Ok(R::from_abi(vmctx, ret.unwrap())) } }) } )*) } impl Func { /// Creates a new `Func` with the given arguments, typically to create a /// user-defined function to pass as an import to a module. /// /// * `store` - a cache of data where information is stored, typically /// shared with a [`Module`](crate::Module). /// /// * `ty` - the signature of this function, used to indicate what the /// inputs and outputs are, which must be WebAssembly types. /// /// * `callable` - a type implementing the [`Callable`] trait which /// is the implementation of this `Func` value. /// /// Note that the implementation of `callable` must adhere to the `ty` /// signature given, error or traps may occur if it does not respect the /// `ty` signature. pub fn new(store: &Store, ty: FuncType, callable: Rc<dyn Callable + 'static>) -> Self { let callable = Rc::new(NativeCallable::new(callable, &ty, &store)); Func::from_wrapped(store, ty, callable) } wrappers! { /// Creates a new `Func` from the given Rust closure, which takes 0 /// arguments. /// /// For more information about this function, see [`Func::wrap1`]. (wrap0) /// Creates a new `Func` from the given Rust closure, which takes 1 /// argument. /// /// This function will create a new `Func` which, when called, will /// execute the given Rust closure. Unlike [`Func::new`] the target /// function being called is known statically so the type signature can /// be inferred. Rust types will map to WebAssembly types as follows: /// /// /// | Rust Argument Type | WebAssembly Type | /// |--------------------|------------------| /// | `i32` | `i32` | /// | `i64` | `i64` | /// | `f32` | `f32` | /// | `f64` | `f64` | /// | (not supported) | `v128` | /// | (not supported) | `anyref` | /// /// Any of the Rust types can be returned from the closure as well, in /// addition to some extra types /// /// | Rust Return Type | WebAssembly Return Type | Meaning | /// |-------------------|-------------------------|-------------------| /// | `()` | nothing | no return value | /// | `Result<T, Trap>` | `T` | function may trap | /// /// Note that when using this API (and the related `wrap*` family of /// functions), the intention is to create as thin of a layer as /// possible for when WebAssembly calls the function provided. With /// sufficient inlining and optimization the WebAssembly will call /// straight into `func` provided, with no extra fluff entailed. (wrap1, A1) /// Creates a new `Func` from the given Rust closure, which takes 2 /// arguments. /// /// For more information about this function, see [`Func::wrap1`]. (wrap2, A1, A2) /// Creates a new `Func` from the given Rust closure, which takes 3 /// arguments. /// /// For more information about this function, see [`Func::wrap1`]. (wrap3, A1, A2, A3) /// Creates a new `Func` from the given Rust closure, which takes 4 /// arguments. /// /// For more information about this function, see [`Func::wrap1`]. (wrap4, A1, A2, A3, A4) /// Creates a new `Func` from the given Rust closure, which takes 5 /// arguments. /// /// For more information about this function, see [`Func::wrap1`]. (wrap5, A1, A2, A3, A4, A5) /// Creates a new `Func` from the given Rust closure, which takes 6 /// arguments. /// /// For more information about this function, see [`Func::wrap1`]. (wrap6, A1, A2, A3, A4, A5, A6) /// Creates a new `Func` from the given Rust closure, which takes 7 /// arguments. /// /// For more information about this function, see [`Func::wrap1`]. (wrap7, A1, A2, A3, A4, A5, A6, A7) /// Creates a new `Func` from the given Rust closure, which takes 8 /// arguments. /// /// For more information about this function, see [`Func::wrap1`]. (wrap8, A1, A2, A3, A4, A5, A6, A7, A8) /// Creates a new `Func` from the given Rust closure, which takes 9 /// arguments. /// /// For more information about this function, see [`Func::wrap1`]. (wrap9, A1, A2, A3, A4, A5, A6, A7, A8, A9) /// Creates a new `Func` from the given Rust closure, which takes 10 /// arguments. /// /// For more information about this function, see [`Func::wrap1`]. (wrap10, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10) } fn from_wrapped( store: &Store, ty: FuncType, callable: Rc<dyn WrappedCallable + 'static>, ) -> Func { Func { _store: store.clone(), callable, ty, } } /// Returns the underlying wasm type that this `Func` has. pub fn ty(&self) -> &FuncType { &self.ty } /// Returns the number of parameters that this function takes. pub fn param_arity(&self) -> usize { self.ty.params().len() } /// Returns the number of results this function produces. pub fn result_arity(&self) -> usize { self.ty.results().len() } /// Invokes this function with the `params` given, returning the results and /// any trap, if one occurs. /// /// The `params` here must match the type signature of this `Func`, or a /// trap will occur. If a trap occurs while executing this function, then a /// trap will also be returned. /// /// This function should not panic unless the underlying function itself /// initiates a panic. pub fn call(&self, params: &[Val]) -> Result<Box<[Val]>, Trap> { let mut results = vec![Val::null(); self.result_arity()]; self.callable.call(params, &mut results)?; Ok(results.into_boxed_slice()) } pub(crate) fn wasmtime_export(&self) -> &wasmtime_runtime::Export { self.callable.wasmtime_export() } pub(crate) fn from_wasmtime_function( export: wasmtime_runtime::Export, store: &Store, instance_handle: InstanceHandle, ) -> Self { // This is only called with `Export::Function`, and since it's coming // from wasmtime_runtime itself we should support all the types coming // out of it, so assert such here. let ty = if let wasmtime_runtime::Export::Function { signature, .. } = &export { FuncType::from_wasmtime_signature(signature.clone()) .expect("core wasm signature should be supported") } else { panic!("expected function export") }; let callable = WasmtimeFn::new(store, instance_handle, export); Func::from_wrapped(store, ty, Rc::new(callable)) } getters! { /// Extracts a natively-callable object from this `Func`, if the /// signature matches. /// /// See the [`Func::get1`] method for more documentation. (get0) /// Extracts a natively-callable object from this `Func`, if the /// signature matches. /// /// This function serves as an optimized version of the [`Func::call`] /// method if the type signature of a function is statically known to /// the program. This method is faster than `call` on a few metrics: /// /// * Runtime type-checking only happens once, when this method is /// called. /// * The result values, if any, aren't boxed into a vector. /// * Arguments and return values don't go through boxing and unboxing. /// * No trampolines are used to transfer control flow to/from JIT code, /// instead this function jumps directly into JIT code. /// /// For more information about which Rust types match up to which wasm /// types, see the documentation on [`Func::wrap1`]. /// /// # Return /// /// This function will return `None` if the type signature asserted /// statically does not match the runtime type signature. `Some`, /// however, will be returned if the underlying function takes one /// parameter of type `A` and returns the parameter `R`. Currently `R` /// can either be `()` (no return values) or one wasm type. At this time /// a multi-value return isn't supported. /// /// The returned closure will always return a `Result<R, Trap>` and an /// `Err` is returned if a trap happens while the wasm is executing. (get1, A1) /// Extracts a natively-callable object from this `Func`, if the /// signature matches. /// /// See the [`Func::get1`] method for more documentation. (get2, A1, A2) /// Extracts a natively-callable object from this `Func`, if the /// signature matches. /// /// See the [`Func::get1`] method for more documentation. (get3, A1, A2, A3) /// Extracts a natively-callable object from this `Func`, if the /// signature matches. /// /// See the [`Func::get1`] method for more documentation. (get4, A1, A2, A3, A4) /// Extracts a natively-callable object from this `Func`, if the /// signature matches. /// /// See the [`Func::get1`] method for more documentation. (get5, A1, A2, A3, A4, A5) /// Extracts a natively-callable object from this `Func`, if the /// signature matches. /// /// See the [`Func::get1`] method for more documentation. (get6, A1, A2, A3, A4, A5, A6) /// Extracts a natively-callable object from this `Func`, if the /// signature matches. /// /// See the [`Func::get1`] method for more documentation. (get7, A1, A2, A3, A4, A5, A6, A7) /// Extracts a natively-callable object from this `Func`, if the /// signature matches. /// /// See the [`Func::get1`] method for more documentation. (get8, A1, A2, A3, A4, A5, A6, A7, A8) /// Extracts a natively-callable object from this `Func`, if the /// signature matches. /// /// See the [`Func::get1`] method for more documentation. (get9, A1, A2, A3, A4, A5, A6, A7, A8, A9) /// Extracts a natively-callable object from this `Func`, if the /// signature matches. /// /// See the [`Func::get1`] method for more documentation. (get10, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10) } } impl fmt::Debug for Func { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "Func") } } /// A trait implemented for types which can be arguments to closures passed to /// [`Func::wrap1`] and friends. /// /// This trait should not be implemented by user types. This trait may change at /// any time internally. The types which implement this trait, however, are /// stable over time. /// /// For more information see [`Func::wrap1`] pub trait WasmTy { #[doc(hidden)] type Abi: Copy; #[doc(hidden)] fn push(dst: &mut Vec<ValType>); #[doc(hidden)] fn matches(tys: impl Iterator<Item = ValType>) -> anyhow::Result<()>; #[doc(hidden)] fn from_abi(vmctx: *mut VMContext, abi: Self::Abi) -> Self; #[doc(hidden)] fn into_abi(self) -> Self::Abi; } impl WasmTy for () { type Abi = (); fn push(_dst: &mut Vec<ValType>) {} fn matches(_tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> { Ok(()) } #[inline] fn from_abi(_vmctx: *mut VMContext, abi: Self::Abi) -> Self { abi } #[inline] fn into_abi(self) -> Self::Abi { self } } impl WasmTy for i32 { type Abi = Self; fn push(dst: &mut Vec<ValType>) { dst.push(ValType::I32); } fn matches(mut tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> { let next = tys.next(); ensure!( next == Some(ValType::I32), "Type mismatch, expected i32, got {:?}", next ); Ok(()) } #[inline] fn from_abi(_vmctx: *mut VMContext, abi: Self::Abi) -> Self { abi } #[inline] fn into_abi(self) -> Self::Abi { self } } impl WasmTy for i64 { type Abi = Self; fn push(dst: &mut Vec<ValType>) { dst.push(ValType::I64); } fn matches(mut tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> { let next = tys.next(); ensure!( next == Some(ValType::I64), "Type mismatch, expected i64, got {:?}", next ); Ok(()) } #[inline] fn from_abi(_vmctx: *mut VMContext, abi: Self::Abi) -> Self { abi } #[inline] fn into_abi(self) -> Self::Abi { self } } impl WasmTy for f32 { type Abi = Self; fn push(dst: &mut Vec<ValType>) { dst.push(ValType::F32); } fn matches(mut tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> { let next = tys.next(); ensure!( next == Some(ValType::F32), "Type mismatch, expected f32, got {:?}", next ); Ok(()) } #[inline] fn from_abi(_vmctx: *mut VMContext, abi: Self::Abi) -> Self { abi } #[inline] fn into_abi(self) -> Self::Abi { self } } impl WasmTy for f64 { type Abi = Self; fn push(dst: &mut Vec<ValType>) { dst.push(ValType::F64); } fn matches(mut tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> { let next = tys.next(); ensure!( next == Some(ValType::F64), "Type mismatch, expected f64, got {:?}", next ); Ok(()) } #[inline] fn from_abi(_vmctx: *mut VMContext, abi: Self::Abi) -> Self { abi } #[inline] fn into_abi(self) -> Self::Abi { self } } /// A trait implemented for types which can be returned from closures passed to /// [`Func::wrap1`] and friends. /// /// This trait should not be implemented by user types. This trait may change at /// any time internally. The types which implement this trait, however, are /// stable over time. /// /// For more information see [`Func::wrap1`] pub trait WasmRet { #[doc(hidden)] type Abi; #[doc(hidden)] fn push(dst: &mut Vec<ValType>); #[doc(hidden)] fn matches(tys: impl Iterator<Item = ValType>) -> anyhow::Result<()>; #[doc(hidden)] fn into_abi(self) -> Self::Abi; } impl<T: WasmTy> WasmRet for T { type Abi = T::Abi; fn push(dst: &mut Vec<ValType>) { T::push(dst) } fn matches(tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> { T::matches(tys) } #[inline] fn into_abi(self) -> Self::Abi { T::into_abi(self) } } impl<T: WasmTy> WasmRet for Result<T, Trap> { type Abi = T::Abi; fn push(dst: &mut Vec<ValType>) { T::push(dst) } fn matches(tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> { T::matches(tys) } #[inline] fn into_abi(self) -> Self::Abi { match self { Ok(val) => return val.into_abi(), Err(trap) => handle_trap(trap), } fn handle_trap(trap: Trap) -> ! { unsafe { wasmtime_runtime::raise_user_trap(Box::new(trap)) } } } }