lib.rs

// 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.

//! # Contract Pallet
//!
//! The Contract module provides functionality for the runtime to deploy and execute WebAssembly
//! smart-contracts.
//!
//! - [`Config`]
//! - [`Call`]
//!
//! ## Overview
//!
//! This module extends accounts based on the [`Currency`] trait to have smart-contract
//! functionality. It can be used with other modules that implement accounts based on [`Currency`].
//! These "smart-contract accounts" have the ability to instantiate smart-contracts and make calls
//! to other contract and non-contract accounts.
//!
//! The smart-contract code is stored once in a code cache, and later retrievable via its hash.
//! This means that multiple smart-contracts can be instantiated from the same hash, without
//! replicating the code each time.
//!
//! When a smart-contract is called, its associated code is retrieved via the code hash and gets
//! executed. This call can alter the storage entries of the smart-contract account, instantiate new
//! smart-contracts, or call other smart-contracts.
//!
//! Finally, when an account is reaped, its associated code and storage of the smart-contract
//! account will also be deleted.
//!
//! ### Gas
//!
//! Senders must specify a gas limit with every call, as all instructions invoked by the
//! smart-contract require gas. Unused gas is refunded after the call, regardless of the execution
//! outcome.
//!
//! If the gas limit is reached, then all calls and state changes (including balance transfers) are
//! only reverted at the current call's contract level. For example, if contract A calls B and B
//! runs out of gas mid-call, then all of B's calls are reverted. Assuming correct error handling by
//! contract A, A's other calls and state changes still persist.
//!
//! ### Notable Scenarios
//!
//! Contract call failures are not always cascading. When failures occur in a sub-call, they do not
//! "bubble up", and the call will only revert at the specific contract level. For example, if
//! contract A calls contract B, and B fails, A can decide how to handle that failure, either
//! proceeding or reverting A's changes.
//!
//! ## Interface
//!
//! ### Dispatchable functions
//!
//! * [`Pallet::instantiate_with_code`] - Deploys a new contract from the supplied wasm binary,
//! optionally transferring
//! some balance. This instantiates a new smart contract account with the supplied code and
//! calls its constructor to initialize the contract.
//! * [`Pallet::instantiate`] - The same as `instantiate_with_code` but instead of uploading new
//! code an existing `code_hash` is supplied.
//! * [`Pallet::call`] - Makes a call to an account, optionally transferring some balance.
//!
//! ## Usage
//!
//! The Contract module is a work in progress. The following examples show how this Contract module
//! can be used to instantiate and call contracts.
//!
//! * [`ink`](https://github.com/paritytech/ink) is
//! an [`eDSL`](https://wiki.haskell.org/Embedded_domain_specific_language) that enables writing
//! WebAssembly based smart contracts in the Rust programming language.

#![cfg_attr(not(feature = "std"), no_std)]
#![cfg_attr(feature = "runtime-benchmarks", recursion_limit = "1024")]

#[macro_use]
mod gas;
mod address;
mod benchmarking;
mod exec;
mod migration;
mod schedule;
mod storage;
mod wasm;

pub mod chain_extension;
pub mod weights;

#[cfg(test)]
mod tests;

use crate::{
	exec::{AccountIdOf, ExecError, Executable, Stack as ExecStack},
	gas::GasMeter,
	storage::{meter::Meter as StorageMeter, ContractInfo, DeletedContract},
	wasm::{OwnerInfo, PrefabWasmModule, TryInstantiate},
	weights::WeightInfo,
};
use codec::{Codec, Encode, HasCompact};
use frame_support::{
	dispatch::{Dispatchable, GetDispatchInfo, Pays, PostDispatchInfo},
	ensure,
	traits::{
		tokens::fungible::Inspect, ConstU32, Contains, Currency, Get, Randomness,
		ReservableCurrency, Time,
	},
	weights::{OldWeight, Weight},
	BoundedVec, WeakBoundedVec,
};
use frame_system::Pallet as System;
use pallet_contracts_primitives::{
	Code, CodeUploadResult, CodeUploadReturnValue, ContractAccessError, ContractExecResult,
	ContractInstantiateResult, ExecReturnValue, GetStorageResult, InstantiateReturnValue,
	StorageDeposit,
};
use scale_info::TypeInfo;
use smallvec::Array;
use sp_runtime::traits::{Convert, Hash, Saturating, StaticLookup};
use sp_std::{fmt::Debug, marker::PhantomData, prelude::*};

pub use crate::{
	address::{AddressGenerator, DefaultAddressGenerator},
	exec::{Frame, VarSizedKey as StorageKey},
	migration::Migration,
	pallet::*,
	schedule::{HostFnWeights, InstructionWeights, Limits, Schedule},
	wasm::Determinism,
};

#[cfg(doc)]
pub use crate::wasm::api_doc;

type CodeHash<T> = <T as frame_system::Config>::Hash;
type TrieId = BoundedVec<u8, ConstU32<128>>;
type BalanceOf<T> =
	<<T as Config>::Currency as Currency<<T as frame_system::Config>::AccountId>>::Balance;
type CodeVec<T> = BoundedVec<u8, <T as Config>::MaxCodeLen>;
type RelaxedCodeVec<T> = WeakBoundedVec<u8, <T as Config>::MaxCodeLen>;
type AccountIdLookupOf<T> = <<T as frame_system::Config>::Lookup as StaticLookup>::Source;
type DebugBufferVec<T> = BoundedVec<u8, <T as Config>::MaxDebugBufferLen>;

/// Used as a sentinel value when reading and writing contract memory.
///
/// It is usually used to signal `None` to a contract when only a primitive is allowed
/// and we don't want to go through encoding a full Rust type. Using `u32::Max` is a safe
/// sentinel because contracts are never allowed to use such a large amount of resources
/// that this value makes sense for a memory location or length.
const SENTINEL: u32 = u32::MAX;

#[frame_support::pallet]
pub mod pallet {
	use super::*;
	use frame_support::pallet_prelude::*;
	use frame_system::pallet_prelude::*;

	/// The current storage version.
	const STORAGE_VERSION: StorageVersion = StorageVersion::new(9);

	#[pallet::pallet]
	#[pallet::storage_version(STORAGE_VERSION)]
	pub struct Pallet<T>(PhantomData<T>);

	#[pallet::config]
	pub trait Config: frame_system::Config {
		/// The time implementation used to supply timestamps to contracts through `seal_now`.
		type Time: Time;

		/// The generator used to supply randomness to contracts through `seal_random`.
		///
		/// # Deprecated
		///
		/// Codes using the randomness functionality cannot be uploaded. Neither can contracts
		/// be instantiated from existing codes that use this deprecated functionality. It will
		/// be removed eventually. Hence for new `pallet-contracts` deployments it is okay
		/// to supply a dummy implementation for this type (because it is never used).
		type Randomness: Randomness<Self::Hash, Self::BlockNumber>;

		/// The currency in which fees are paid and contract balances are held.
		type Currency: ReservableCurrency<Self::AccountId>
			+ Inspect<Self::AccountId, Balance = BalanceOf<Self>>;

		/// The overarching event type.
		type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;

		/// The overarching call type.
		type RuntimeCall: Dispatchable<RuntimeOrigin = Self::RuntimeOrigin, PostInfo = PostDispatchInfo>
			+ GetDispatchInfo
			+ codec::Decode
			+ IsType<<Self as frame_system::Config>::RuntimeCall>;