// This file is part of Substrate. // Copyright (C) Parity Technologies (UK) Ltd. // SPDX-License-Identifier: Apache-2.0 // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. //! Substrate runtime interface //! //! This crate provides types, traits and macros around runtime interfaces. A runtime interface is //! a fixed interface between a Substrate runtime (also called the "guest") and a Substrate node //! (also called the "host"). For a native runtime the interface maps to direct function calls of //! the implementation. For a non-native runtime the interface maps to an external function call. //! These external functions are exported by the runtime and they map to the same implementation //! as the native calls, just with some extra code to marshal them through the FFI boundary. //! //! # Using a type in a runtime interface //! //! Every argument type and return type must be wrapped in a marker newtype specifying the //! marshalling strategy used to pass the value through the FFI boundary between the host //! and the runtime. The only exceptions to this rule are a couple of basic, primitive types //! which can be passed directly through the FFI boundary and which don't require any special //! handling besides a straightforward, direct conversion. //! //! You can find the strategy wrapper types in the [`crate::pass_by`] module. //! //! The newtype wrappers are automatically stripped away when the function is called //! and applied when the function returns by the `runtime_interface` macro. //! //! # Declaring a runtime interface //! //! Declaring a runtime interface is similar to declaring a trait in Rust: //! //! ``` //! # mod wrapper { //! # use sp_runtime_interface::pass_by::PassFatPointerAndRead; //! //! #[sp_runtime_interface::runtime_interface] //! trait RuntimeInterface { //! fn some_function(value: PassFatPointerAndRead<&[u8]>) -> bool { //! value.iter().all(|v| *v > 125) //! } //! } //! # } //! ``` //! //! For more information on declaring a runtime interface, see //! [`#[runtime_interface]`](./attr.runtime_interface.html). #![no_std] pub extern crate alloc; extern crate self as sp_runtime_interface; #[doc(hidden)] #[cfg(not(substrate_runtime))] pub use sp_wasm_interface; #[doc(hidden)] pub use sp_tracing; #[doc(hidden)] pub use sp_std; /// Attribute macro for transforming a trait declaration into a runtime interface. /// /// A runtime interface is a fixed interface between a Substrate compatible runtime and the /// native node. This interface is callable from a native and a wasm runtime. The macro will /// generate the corresponding code for the native implementation and the code for calling from /// the wasm side to the native implementation. /// /// The macro expects the runtime interface declaration as trait declaration: /// /// ``` /// # mod wrapper { /// # use sp_runtime_interface::runtime_interface; /// # use sp_runtime_interface::pass_by::{PassFatPointerAndDecode, PassFatPointerAndRead, AllocateAndReturnFatPointer}; /// /// #[runtime_interface] /// trait Interface { /// /// A function that can be called from native/wasm. /// /// /// /// The implementation given to this function is only compiled on native. /// fn call(data: PassFatPointerAndRead<&[u8]>) -> AllocateAndReturnFatPointer> { /// // Here you could call some rather complex code that only compiles on native or /// // is way faster in native than executing it in wasm. /// Vec::new() /// } /// /// Call function, but different version. /// /// /// /// For new runtimes, only function with latest version is reachable. /// /// But old version (above) is still accessible for old runtimes. /// /// Default version is 1. /// #[version(2)] /// fn call(data: PassFatPointerAndRead<&[u8]>) -> AllocateAndReturnFatPointer> { /// // Here you could call some rather complex code that only compiles on native or /// // is way faster in native than executing it in wasm. /// [17].to_vec() /// } /// /// /// Call function, different version and only being registered. /// /// /// /// This `register_only` version is only being registered, aka exposed to the runtime, /// /// but the runtime will still use the version 2 of this function. This is useful for when /// /// new host functions should be introduced. Adding new host functions requires that all /// /// nodes have the host functions available, because otherwise they fail at instantiation /// /// of the runtime. With `register_only` the function will not be used when compiling the /// /// runtime, but it will already be there for a future version of the runtime that will /// /// switch to using these host function. /// #[version(3, register_only)] /// fn call(data: PassFatPointerAndRead<&[u8]>) -> AllocateAndReturnFatPointer> { /// // Here you could call some rather complex code that only compiles on native or /// // is way faster in native than executing it in wasm. /// [18].to_vec() /// } /// /// /// A function can take a `&self` or `&mut self` argument to get access to the /// /// `Externalities`. (The generated method does not require /// /// this argument, so the function can be called just with the `optional` argument) /// fn set_or_clear(&mut self, optional: PassFatPointerAndDecode>>) { /// match optional { /// Some(value) => self.set_storage([1, 2, 3, 4].to_vec(), value), /// None => self.clear_storage(&[1, 2, 3, 4]), /// } /// } /// /// /// A function can be gated behind a configuration (`cfg`) attribute. /// /// To prevent ambiguity and confusion about what will be the final exposed host /// /// functions list, conditionally compiled functions can't be versioned. /// /// That is, conditionally compiled functions with `version`s greater than 1 /// /// are not allowed. /// #[cfg(feature = "experimental-function")] /// fn gated_call(data: PassFatPointerAndRead<&[u8]>) -> AllocateAndReturnFatPointer> { /// [42].to_vec() /// } /// } /// # } /// ``` /// /// The given example will generate roughly the following code for native: /// /// ``` /// // The name of the trait is converted to snake case and used as mod name. /// // /// // Be aware that this module is not `public`, the visibility of the module is determined based /// // on the visibility of the trait declaration. /// mod interface { /// trait Interface { /// fn call_version_1(data: &[u8]) -> Vec; /// fn call_version_2(data: &[u8]) -> Vec; /// fn call_version_3(data: &[u8]) -> Vec; /// fn set_or_clear_version_1(&mut self, optional: Option>); /// #[cfg(feature = "experimental-function")] /// fn gated_call_version_1(data: &[u8]) -> Vec; /// } /// /// impl Interface for &mut dyn sp_externalities::Externalities { /// fn call_version_1(data: &[u8]) -> Vec { Vec::new() } /// fn call_version_2(data: &[u8]) -> Vec { [17].to_vec() } /// fn call_version_3(data: &[u8]) -> Vec { [18].to_vec() } /// fn set_or_clear_version_1(&mut self, optional: Option>) { /// match optional { /// Some(value) => self.set_storage([1, 2, 3, 4].to_vec(), value), /// None => self.clear_storage(&[1, 2, 3, 4]), /// } /// } /// #[cfg(feature = "experimental-function")] /// fn gated_call_version_1(data: &[u8]) -> Vec { [42].to_vec() } /// } /// /// pub fn call(data: &[u8]) -> Vec { /// // only latest version is exposed /// call_version_2(data) /// } /// /// fn call_version_1(data: &[u8]) -> Vec { /// <&mut dyn sp_externalities::Externalities as Interface>::call_version_1(data) /// } /// /// fn call_version_2(data: &[u8]) -> Vec { /// <&mut dyn sp_externalities::Externalities as Interface>::call_version_2(data) /// } /// /// fn call_version_3(data: &[u8]) -> Vec { /// <&mut dyn sp_externalities::Externalities as Interface>::call_version_3(data) /// } /// /// pub fn set_or_clear(optional: Option>) { /// set_or_clear_version_1(optional) /// } /// /// fn set_or_clear_version_1(optional: Option>) { /// sp_externalities::with_externalities(|mut ext| Interface::set_or_clear_version_1(&mut ext, optional)) /// .expect("`set_or_clear` called outside of an Externalities-provided environment.") /// } /// /// #[cfg(feature = "experimental-function")] /// pub fn gated_call(data: &[u8]) -> Vec { /// gated_call_version_1(data) /// } /// /// #[cfg(feature = "experimental-function")] /// fn gated_call_version_1(data: &[u8]) -> Vec { /// <&mut dyn sp_externalities::Externalities as Interface>::gated_call_version_1(data) /// } /// /// /// This type implements the `HostFunctions` trait (from `sp-wasm-interface`) and /// /// provides the host implementation for the wasm side. The host implementation converts the /// /// arguments from wasm to native and calls the corresponding native function. /// /// /// /// This type needs to be passed to the wasm executor, so that the host functions will be /// /// registered in the executor. /// pub struct HostFunctions; /// } /// ``` /// /// The given example will generate roughly the following code for wasm: /// /// ``` /// mod interface { /// mod extern_host_functions_impls { /// /// Every function is exported by the native code as `ext_FUNCTION_NAME_version_VERSION`. /// /// /// /// The type for each argument of the exported function depends on /// /// `::FFIType`. /// /// /// /// `key` holds the pointer and the length to the `data` slice. /// pub fn call(data: &[u8]) -> Vec { /// extern "C" { pub fn ext_call_version_2(key: u64); } /// // Should call into external `ext_call_version_2(<[u8] as IntoFFIValue>::into_ffi_value(key))` /// // But this is too much to replicate in a doc test so here we just return a dummy vector. /// // Note that we jump into the latest version not marked as `register_only` (i.e. version 2). /// Vec::new() /// } /// /// /// `key` holds the pointer and the length of the `option` value. /// pub fn set_or_clear(option: Option>) { /// extern "C" { pub fn ext_set_or_clear_version_1(key: u64); } /// // Same as above /// } /// /// /// `key` holds the pointer and the length to the `data` slice. /// #[cfg(feature = "experimental-function")] /// pub fn gated_call(data: &[u8]) -> Vec { /// extern "C" { pub fn ext_gated_call_version_1(key: u64); } /// /// Same as above /// Vec::new() /// } /// } /// /// /// The type is actually `ExchangeableFunction` (from `sp-runtime-interface`) and /// /// by default this is initialized to jump into the corresponding function in /// /// `extern_host_functions_impls`. /// /// /// /// This can be used to replace the implementation of the `call` function. /// /// Instead of calling into the host, the callee will automatically call the other /// /// implementation. /// /// /// /// To replace the implementation: /// /// /// /// `host_call.replace_implementation(some_other_impl)` /// pub static host_call: () = (); /// pub static host_set_or_clear: () = (); /// #[cfg(feature = "experimental-feature")] /// pub static gated_call: () = (); /// /// pub fn call(data: &[u8]) -> Vec { /// // This is the actual call: `host_call.get()(data)` /// // /// // But that does not work for several reasons in this example, so we just return an /// // empty vector. /// Vec::new() /// } /// /// pub fn set_or_clear(optional: Option>) { /// // Same as above /// } /// /// #[cfg(feature = "experimental-feature")] /// pub fn gated_call(data: &[u8]) -> Vec { /// // Same as above /// Vec::new() /// } /// } /// ``` /// /// # Argument and return types /// /// Every argument type and return type must be wrapped in a marker newtype specifying the /// marshalling strategy used to pass the value through the FFI boundary between the host /// and the runtime. The only exceptions to this rule are a couple of basic, primitive types /// which can be passed directly through the FFI boundary and which don't require any special /// handling besides a straightforward, direct conversion. /// /// The following table documents those types which can be passed between the host and the /// runtime without a marshalling strategy wrapper: /// /// | Type | FFI type | Conversion | /// |----|----|----| /// | `u8` | `u32` | zero-extended to 32-bits | /// | `u16` | `u32` | zero-extended to 32-bits | /// | `u32` | `u32` | `Identity` | /// | `u64` | `u64` | `Identity` | /// | `i8` | `i32` | sign-extended to 32-bits | /// | `i16` | `i32` | sign-extended to 32-bits | /// | `i32` | `i32` | `Identity` | /// | `i64` | `i64` | `Identity` | /// | `bool` | `u32` | `if v { 1 } else { 0 }` | /// | `*const T` | `u32` | `Identity` | /// /// `Identity` means that the value is passed as-is directly in a bit-exact fashion. /// /// You can find the strategy wrapper types in the [`crate::pass_by`] module. /// /// The newtype wrappers are automatically stripped away when the function is called /// and applied when the function returns by the `runtime_interface` macro. /// /// # Wasm only interfaces /// /// Some interfaces are only required from within the wasm runtime e.g. the allocator /// interface. To support this, the macro can be called like `#[runtime_interface(wasm_only)]`. /// This instructs the macro to make two significant changes to the generated code: /// /// 1. The generated functions are not callable from the native side. /// 2. The trait as shown above is not implemented for [`Externalities`] and is instead /// implemented for `FunctionContext` (from `sp-wasm-interface`). /// /// # Disable tracing /// By adding `no_tracing` to the list of options you can prevent the wasm-side interface from /// generating the default `sp-tracing`-calls. Note that this is rarely needed but only meant /// for the case when that would create a circular dependency. You usually _do not_ want to add /// this flag, as tracing doesn't cost you anything by default anyways (it is added as a no-op) /// but is super useful for debugging later. pub use sp_runtime_interface_proc_macro::runtime_interface; #[doc(hidden)] #[cfg(not(substrate_runtime))] pub use sp_externalities::{ set_and_run_with_externalities, with_externalities, ExtensionStore, Externalities, ExternalitiesExt, }; #[doc(hidden)] pub use codec; #[cfg(all(any(target_arch = "riscv32", target_arch = "riscv64"), substrate_runtime))] pub mod polkavm; #[cfg(not(substrate_runtime))] pub mod host; pub(crate) mod impls; pub mod pass_by; #[cfg(any(substrate_runtime, doc))] pub mod wasm; mod util; pub use util::{pack_ptr_and_len, unpack_ptr_and_len}; /// Something that can be used by the runtime interface as type to communicate between the runtime /// and the host. /// /// Every type that should be used in a runtime interface function signature needs to implement /// this trait. pub trait RIType: Sized { /// The raw FFI type that is used to pass `Self` through the host <-> runtime boundary. #[cfg(not(substrate_runtime))] type FFIType: sp_wasm_interface::IntoValue + sp_wasm_interface::TryFromValue + sp_wasm_interface::WasmTy; #[cfg(substrate_runtime)] type FFIType; /// The inner type without any serialization strategy wrapper. type Inner; } /// A raw pointer that can be used in a runtime interface function signature. #[cfg(substrate_runtime)] pub type Pointer = *mut T; /// A raw pointer that can be used in a runtime interface function signature. #[cfg(not(substrate_runtime))] pub type Pointer = sp_wasm_interface::Pointer;