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// Copyright 2018-2020 Parity Technologies (UK) Ltd. // // 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. //! Utilities and helper routines that are useful for both ink! messages //! and ink! constructors. use crate::ir; use core::fmt; use proc_macro2::{ Ident, Span, }; use quote::ToTokens as _; use syn::spanned::Spanned as _; /// The kind of externally callable smart contract entity. #[derive(Debug, Copy, Clone)] pub enum CallableKind { /// An ink! message externally callable. Message, /// An ink! constructor externally callable. Constructor, } impl fmt::Display for CallableKind { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { match self { Self::Message => write!(f, "message"), Self::Constructor => write!(f, "constructor"), } } } /// Wrapper for a callable that adds its composed selector. #[derive(Debug)] pub struct CallableWithSelector<'a, C> { /// The composed selector computed by the associated implementation block /// and the given callable. composed_selector: ir::Selector, /// The parent implementation block. item_impl: &'a ir::ItemImpl, /// The actual callable. callable: &'a C, } impl<C> Copy for CallableWithSelector<'_, C> {} impl<C> Clone for CallableWithSelector<'_, C> { fn clone(&self) -> Self { Self { composed_selector: self.composed_selector, item_impl: self.item_impl, callable: self.callable, } } } impl<'a, C> CallableWithSelector<'a, C> where C: Callable, { /// Creates a new wrapper around the given callable and parent impl block. pub(super) fn new(item_impl: &'a ir::ItemImpl, callable: &'a C) -> Self { Self { composed_selector: compose_selector(item_impl, callable), item_impl, callable, } } } impl<'a, C> CallableWithSelector<'a, C> { /// Returns the composed selector of the ink! callable the the impl block. pub fn composed_selector(&self) -> ir::Selector { self.composed_selector } /// Returns a shared reference to the underlying callable. pub fn callable(&self) -> &'a C { self.callable } /// Returns the parent implementation block of the ink! callable. pub fn item_impl(&self) -> &'a ir::ItemImpl { self.item_impl } } impl<'a, C> Callable for CallableWithSelector<'a, C> where C: Callable, { fn kind(&self) -> CallableKind { <C as Callable>::kind(&self.callable) } fn ident(&self) -> &Ident { <C as Callable>::ident(&self.callable) } fn user_provided_selector(&self) -> Option<&ir::Selector> { <C as Callable>::user_provided_selector(&self.callable) } fn is_payable(&self) -> bool { <C as Callable>::is_payable(&self.callable) } fn visibility(&self) -> Visibility { <C as Callable>::visibility(&self.callable) } fn inputs(&self) -> InputsIter { <C as Callable>::inputs(&self.callable) } fn inputs_span(&self) -> Span { <C as Callable>::inputs_span(&self.callable) } fn statements(&self) -> &[syn::Stmt] { <C as Callable>::statements(&self.callable) } } impl<'a, C> ::core::ops::Deref for CallableWithSelector<'a, C> { type Target = C; fn deref(&self) -> &Self::Target { &self.callable } } /// An ink! callable. /// /// This is either an ink! message or an ink! constructor. /// Used to share common behavior between different callable types. pub trait Callable { /// Returns the kind of the ink! callable. fn kind(&self) -> CallableKind; /// Returns the identifier of the ink! callable. fn ident(&self) -> &Ident; /// Returns the selector of the ink! callable if any has been manually set. fn user_provided_selector(&self) -> Option<&ir::Selector>; /// Returns `true` if the ink! callable is flagged as payable. /// /// # Note /// /// Flagging as payable is done using the `#[ink(payable)]` attribute. fn is_payable(&self) -> bool; /// Returns the visibility of the ink! callable. fn visibility(&self) -> Visibility; /// Returns an iterator yielding all input parameters of the ink! callable. fn inputs(&self) -> InputsIter; /// Returns the span of the inputs of the ink! callable. fn inputs_span(&self) -> Span; /// Returns a slice over shared references to the statements of the callable. fn statements(&self) -> &[syn::Stmt]; } /// Returns the composed selector of the ink! callable. /// /// Composition takes into account the given [`ir::ItemImpl`]. /// /// # Details /// /// Given /// - the callable's identifier `i` /// - the optionally set callable's selector `s` /// - the impl blocks trait path in case it implements a trait, `P` /// - the impl blocks optional user provided namespace `S` /// /// Then the selector is composed in the following way: /// /// - If `s` is given we simply return `s`. /// - Otherwise if `T` is not `None` (trait impl block) we concatenate /// `S`, `T` and `i` with `::` as separator if `T` refers to a full-path. /// If `T` refers to a relative path or is just an identifier we only take /// its last segment `p` (e.g. the trait's identifier) into consideration /// and use it instead of `P` in the above concatenation. /// In the following we refer to the resulting concatenation as `C`. /// - Now we take the BLAKE-2 hash of `C` which results in 32 bytes of output /// and take the first 4 bytes that are returned in order as the composed /// selector. /// /// # Examples /// /// ## Overriding the composed selector /// /// Given /// /// ```no_compile /// impl MyStorage { /// #[ink(message, selector = "0xDEADBEEF")] /// fn my_message(&self) {} /// } /// ``` /// /// ... then the selector of `my_message` is simply `0xDEADBEEF` since it overrides /// the composed selector. /// /// ## Inherent implementation block /// /// Given /// /// ```no_compile /// impl MyStorage { /// #[ink(message)] /// fn my_message(&self) {} /// } /// ``` /// /// ... then the selector of `my_message` is composed such as: /// ```no_compile /// BLAKE2("my_message".to_string().as_bytes())[0..4] /// ``` /// /// ## Trait implementation block /// /// Given /// /// ```no_compile /// impl MyTrait for MyStorage { /// #[ink(message)] /// fn my_message(&self) {} /// } /// ``` /// /// ... then the selector of `my_message` is composed such as: /// ```no_compile /// BLAKE2("MyTrait::my_message".to_string().as_bytes())[0..4] /// ``` /// /// ## Using full path for trait /// /// Given /// /// ```no_compile /// impl ::my_full::long_path::MyTrait for MyStorage { /// #[ink(message)] /// fn my_message(&self) {} /// } /// ``` /// /// ... then the selector of `my_message` is composed such as: /// ```no_compile /// BLAKE2("::my_full::long_path::MyTrait::my_message".to_string().as_bytes())[0..4] /// ``` /// /// ## Using a namespace /// /// Given /// /// ```no_compile /// #[ink(namespace = "my_namespace")] /// impl MyTrait for MyStorage { /// #[ink(message)] /// fn my_message(&self) {} /// } /// ``` /// /// ... then the selector of `my_message` is composed such as: /// ```no_compile /// BLAKE2("my_namespace::MyTrait::my_message".to_string().as_bytes())[0..4] /// ``` /// /// ## Note /// /// All above examples work similarly for ink! constructors interchangeably. /// /// ## Usage Recommendations /// /// These recommendation mainly apply to trait implementation blocks: /// /// - The recommandation by the ink! team is to use the full-path approach /// wherever possible; OR import the trait and use only its identifier with /// an additional namespace if required to disambiguate selectors. /// - Try not to intermix the above recommendations. /// - Avoid directly setting the selector of an ink! message or constuctor. /// Only do this if nothing else helps and you need a very specific selector, /// e.g. in case of backwards compatibility. /// - Do not use the namespace unless required to disambiguate. pub fn compose_selector<C>(item_impl: &ir::ItemImpl, callable: &C) -> ir::Selector where C: Callable, { if let Some(selector) = callable.user_provided_selector() { return *selector } let callable_ident = callable.ident().to_string().into_bytes(); let namespace_bytes = item_impl .namespace() .map(|namespace| namespace.as_bytes().to_vec()) .unwrap_or_default(); let separator = &b"::"[..]; let joined = match item_impl.trait_path() { None => { // Inherent implementation block: if namespace_bytes.is_empty() { callable_ident } else { [namespace_bytes, callable_ident].join(separator) } } Some(path) => { // Trait implementation block: // // We need to separate between full-path, e.g. `::my::full::Path` // starting with `::` and relative paths for the composition. let path_bytes = if path.leading_colon.is_some() { let mut str_repr = path.to_token_stream().to_string(); str_repr.retain(|c| !c.is_whitespace()); str_repr.into_bytes() } else { path.segments .last() .expect("encountered empty trait path") .ident .to_string() .into_bytes() }; if namespace_bytes.is_empty() { [path_bytes, callable_ident].join(separator) } else { [namespace_bytes, path_bytes, callable_ident].join(separator) } } }; let hash = <blake2::Blake2b as blake2::Digest>::digest(&joined); ir::Selector::new([hash[0], hash[1], hash[2], hash[3]]) } /// Ensures that common invariants of externally callable ink! entities are met. /// /// # Errors /// /// In case any of the common externally callable invariants are not met: /// - This is `true` if the externally callable is: /// - generic /// - const (compile-time evaluatable) /// - async (async WebAssembly smart contract calling is not allowed) /// - unsafe (caller provided assertions not yet stable) /// - Furthermore this is `true` if the externally callable is defined for a /// non default ABI (e.g. `extern "C"`) or doesn't have valid visibility. pub(super) fn ensure_callable_invariants( method_item: &syn::ImplItemMethod, kind: CallableKind, ) -> Result<(), syn::Error> { let bad_visibility = match &method_item.vis { syn::Visibility::Inherited => None, syn::Visibility::Restricted(vis_restricted) => Some(vis_restricted.span()), syn::Visibility::Crate(vis_crate) => Some(vis_crate.span()), syn::Visibility::Public(_) => None, }; if let Some(bad_visibility) = bad_visibility { return Err(format_err!( bad_visibility, "ink! {}s must have public or inherited visibility", kind )) } if !method_item.sig.generics.params.is_empty() { return Err(format_err_spanned!( method_item.sig.generics.params, "ink! {}s must not be generic", kind, )) } if method_item.sig.constness.is_some() { return Err(format_err_spanned!( method_item.sig.constness, "ink! {}s must not be const", kind, )) } if method_item.sig.asyncness.is_some() { return Err(format_err_spanned!( method_item.sig.asyncness, "ink! {}s must not be async", kind, )) } if method_item.sig.unsafety.is_some() { return Err(format_err_spanned!( method_item.sig.unsafety, "ink! {}s must not be unsafe", kind, )) } if method_item.sig.abi.is_some() { return Err(format_err_spanned!( method_item.sig.abi, "ink! {}s must have explicit ABI", kind, )) } if method_item.sig.variadic.is_some() { return Err(format_err_spanned!( method_item.sig.variadic, "ink! {}s must not be variadic", kind, )) } Ok(()) } /// The visibility of an ink! message or constructor. #[derive(Debug, Clone)] pub enum Visibility { Public(syn::VisPublic), Inherited, } impl Visibility { /// Returns `true` if the visibility of the ink! message of constructor is public (`pub`). /// /// # Note /// /// Messages in normal implementation blocks must have public visibility. pub fn is_pub(&self) -> bool { matches!(self, Self::Public(_)) } /// Returns `true` if the visibility of the ink! message of constructor is inherited. /// /// # Note /// /// Messages in trait implementation blocks must have inherited visibility. pub fn is_inherited(&self) -> bool { matches!(self, Self::Inherited) } /// Returns the associated span if any. pub fn span(&self) -> Option<Span> { match self { Self::Public(vis_public) => Some(vis_public.span()), Self::Inherited => None, } } } /// Iterator over the input parameters of an ink! message or constructor. /// /// Does not yield the self receiver of ink! messages. pub struct InputsIter<'a> { iter: syn::punctuated::Iter<'a, syn::FnArg>, } impl<'a> From<&'a ir::Message> for InputsIter<'a> { fn from(message: &'a ir::Message) -> Self { Self { iter: message.item.sig.inputs.iter(), } } } impl<'a> From<&'a ir::Constructor> for InputsIter<'a> { fn from(constructor: &'a ir::Constructor) -> Self { Self { iter: constructor.item.sig.inputs.iter(), } } } impl<'a> Iterator for InputsIter<'a> { type Item = &'a syn::PatType; fn next(&mut self) -> Option<Self::Item> { 'repeat: loop { match self.iter.next() { None => return None, Some(syn::FnArg::Typed(pat_typed)) => return Some(pat_typed), Some(syn::FnArg::Receiver(_)) => continue 'repeat, } } } } #[cfg(test)] mod tests { use super::*; use core::{ convert::TryFrom, fmt::Debug, }; pub enum ExpectedSelector { Raw([u8; 4]), Blake2(Vec<u8>), } impl From<[u8; 4]> for ExpectedSelector { fn from(raw_selector: [u8; 4]) -> Self { ExpectedSelector::Raw(raw_selector) } } impl From<Vec<u8>> for ExpectedSelector { fn from(blake2_input: Vec<u8>) -> Self { ExpectedSelector::Blake2(blake2_input) } } impl ExpectedSelector { pub fn expected_selector(self) -> ir::Selector { match self { Self::Raw(raw_selector) => ir::Selector::new(raw_selector), Self::Blake2(blake2_input) => { let hash = <blake2::Blake2b as blake2::Digest>::digest(&blake2_input); ir::Selector::new([hash[0], hash[1], hash[2], hash[3]]) } } } } /// Asserts that the given ink! implementation block and the given ink! /// message result in the same composed selector as the expected bytes. fn assert_compose_selector<C, S>( item_impl: syn::ItemImpl, item_method: syn::ImplItemMethod, expected_selector: S, ) where C: Callable + TryFrom<syn::ImplItemMethod>, <C as TryFrom<syn::ImplItemMethod>>::Error: Debug, S: Into<ExpectedSelector>, { assert_eq!( compose_selector( &<ir::ItemImpl as TryFrom<syn::ItemImpl>>::try_from(item_impl).unwrap(), &<C as TryFrom<syn::ImplItemMethod>>::try_from(item_method).unwrap(), ), expected_selector.into().expected_selector(), ) } #[test] fn compose_selector_works() { assert_compose_selector::<ir::Message, _>( syn::parse_quote! { #[ink(impl)] impl MyStorage {} }, syn::parse_quote! { #[ink(message)] fn my_message(&self) {} }, b"my_message".to_vec(), ); assert_compose_selector::<ir::Message, _>( syn::parse_quote! { #[ink(impl)] impl MyTrait for MyStorage {} }, syn::parse_quote! { #[ink(message)] fn my_message(&self) {} }, b"MyTrait::my_message".to_vec(), ); assert_compose_selector::<ir::Message, _>( syn::parse_quote! { #[ink(impl)] impl ::my::full::path::MyTrait for MyStorage {} }, syn::parse_quote! { #[ink(message)] fn my_message(&self) {} }, b"::my::full::path::MyTrait::my_message".to_vec(), ); assert_compose_selector::<ir::Message, _>( syn::parse_quote! { #[ink(impl, namespace = "my_namespace")] impl MyTrait for MyStorage {} }, syn::parse_quote! { #[ink(message)] fn my_message(&self) {} }, b"my_namespace::MyTrait::my_message".to_vec(), ); assert_compose_selector::<ir::Message, _>( syn::parse_quote! { #[ink(impl)] impl MyTrait for MyStorage {} }, syn::parse_quote! { #[ink(message, selector = "0xDEADBEEF")] fn my_message(&self) {} }, [0xDE, 0xAD, 0xBE, 0xEF], ); assert_compose_selector::<ir::Message, _>( syn::parse_quote! { #[ink(impl)] impl relative::path_to::MyTrait for MyStorage {} }, syn::parse_quote! { #[ink(message)] fn my_message(&self) {} }, b"MyTrait::my_message".to_vec(), ); } }