exec.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.

use crate::{
	debug::{CallInterceptor, CallSpan, Tracing},
	gas::GasMeter,
	limits,
	primitives::{ExecReturnValue, StorageDeposit},
	runtime_decl_for_revive_api::{Decode, Encode, RuntimeDebugNoBound, TypeInfo},
	storage::{self, meter::Diff, WriteOutcome},
	transient_storage::TransientStorage,
	BalanceOf, CodeHash, CodeInfo, CodeInfoOf, Config, ContractInfo, ContractInfoOf, DebugBuffer,
	Error, Event, Pallet as Contracts, LOG_TARGET,
};
use alloc::vec::Vec;
use core::{fmt::Debug, marker::PhantomData, mem};
use frame_support::{
	crypto::ecdsa::ECDSAExt,
	dispatch::{DispatchResult, DispatchResultWithPostInfo},
	ensure,
	storage::{with_transaction, TransactionOutcome},
	traits::{
		fungible::{Inspect, Mutate},
		tokens::{Fortitude, Preservation},
		Contains, OriginTrait, Time,
	},
	weights::Weight,
	Blake2_128Concat, BoundedVec, StorageHasher,
};
use frame_system::{
	pallet_prelude::{BlockNumberFor, OriginFor},
	Pallet as System, RawOrigin,
};
use sp_core::{
	ecdsa::Public as ECDSAPublic,
	sr25519::{Public as SR25519Public, Signature as SR25519Signature},
	ConstU32, Get,
};
use sp_io::{crypto::secp256k1_ecdsa_recover_compressed, hashing::blake2_256};
use sp_runtime::{
	traits::{BadOrigin, Convert, Dispatchable, Zero},
	DispatchError,
};

pub type AccountIdOf<T> = <T as frame_system::Config>::AccountId;
pub type MomentOf<T> = <<T as Config>::Time as Time>::Moment;
pub type ExecResult = Result<ExecReturnValue, ExecError>;

/// A type that represents a topic of an event. At the moment a hash is used.
pub type TopicOf<T> = <T as frame_system::Config>::Hash;

/// Type for variable sized storage key. Used for transparent hashing.
type VarSizedKey = BoundedVec<u8, ConstU32<{ limits::STORAGE_KEY_BYTES }>>;

/// Combined key type for both fixed and variable sized storage keys.
pub enum Key {
	/// Variant for fixed sized keys.
	Fix([u8; 32]),
	/// Variant for variable sized keys.
	Var(VarSizedKey),
}

impl Key {
	/// Reference to the raw unhashed key.
	///
	/// # Note
	///
	/// Only used by benchmarking in order to generate storage collisions on purpose.
	#[cfg(feature = "runtime-benchmarks")]
	pub fn unhashed(&self) -> &[u8] {
		match self {
			Key::Fix(v) => v.as_ref(),
			Key::Var(v) => v.as_ref(),
		}
	}

	/// The hashed key that has be used as actual key to the storage trie.
	pub fn hash(&self) -> Vec<u8> {
		match self {
			Key::Fix(v) => blake2_256(v.as_slice()).to_vec(),
			Key::Var(v) => Blake2_128Concat::hash(v.as_slice()),
		}
	}

	pub fn from_fixed(v: [u8; 32]) -> Self {
		Self::Fix(v)
	}

	pub fn try_from_var(v: Vec<u8>) -> Result<Self, ()> {
		VarSizedKey::try_from(v).map(Self::Var).map_err(|_| ())
	}
}

/// Origin of the error.
///
/// Call or instantiate both called into other contracts and pass through errors happening
/// in those to the caller. This enum is for the caller to distinguish whether the error
/// happened during the execution of the callee or in the current execution context.
#[derive(Copy, Clone, PartialEq, Eq, Debug, codec::Decode, codec::Encode)]
pub enum ErrorOrigin {
	/// Caller error origin.
	///
	/// The error happened in the current execution context rather than in the one
	/// of the contract that is called into.
	Caller,
	/// The error happened during execution of the called contract.
	Callee,
}

/// Error returned by contract execution.
#[derive(Copy, Clone, PartialEq, Eq, Debug, codec::Decode, codec::Encode)]
pub struct ExecError {
	/// The reason why the execution failed.
	pub error: DispatchError,
	/// Origin of the error.
	pub origin: ErrorOrigin,
}

impl<T: Into<DispatchError>> From<T> for ExecError {
	fn from(error: T) -> Self {
		Self { error: error.into(), origin: ErrorOrigin::Caller }
	}
}

/// The type of origins supported by the contracts pallet.
#[derive(Clone, Encode, Decode, PartialEq, TypeInfo, RuntimeDebugNoBound)]
pub enum Origin<T: Config> {
	Root,
	Signed(T::AccountId),
}

impl<T: Config> Origin<T> {
	/// Creates a new Signed Caller from an AccountId.
	pub fn from_account_id(account_id: T::AccountId) -> Self {
		Origin::Signed(account_id)
	}
	/// Creates a new Origin from a `RuntimeOrigin`.
	pub fn from_runtime_origin(o: OriginFor<T>) -> Result<Self, DispatchError> {
		match o.into() {
			Ok(RawOrigin::Root) => Ok(Self::Root),
			Ok(RawOrigin::Signed(t)) => Ok(Self::Signed(t)),
			_ => Err(BadOrigin.into()),
		}
	}
	/// Returns the AccountId of a Signed Origin or an error if the origin is Root.
	pub fn account_id(&self) -> Result<&T::AccountId, DispatchError> {
		match self {
			Origin::Signed(id) => Ok(id),
			Origin::Root => Err(DispatchError::RootNotAllowed),
		}
	}
}

/// An interface that provides access to the external environment in which the
/// smart-contract is executed.
///
/// This interface is specialized to an account of the executing code, so all
/// operations are implicitly performed on that account.
///
/// # Note
///
/// This trait is sealed and cannot be implemented by downstream crates.
pub trait Ext: sealing::Sealed {
	type T: Config;

	/// Call (possibly transferring some amount of funds) into the specified account.
	///
	/// Returns the code size of the called contract.
	fn call(
		&mut self,
		gas_limit: Weight,
		deposit_limit: BalanceOf<Self::T>,
		to: AccountIdOf<Self::T>,
		value: BalanceOf<Self::T>,
		input_data: Vec<u8>,
		allows_reentry: bool,
		read_only: bool,
	) -> Result<ExecReturnValue, ExecError>;

	/// Execute code in the current frame.
	///
	/// Returns the code size of the called contract.
	fn delegate_call(
		&mut self,
		code: CodeHash<Self::T>,
		input_data: Vec<u8>,
	) -> Result<ExecReturnValue, ExecError>;

	/// Instantiate a contract from the given code.
	///
	/// Returns the original code size of the called contract.
	/// The newly created account will be associated with `code`. `value` specifies the amount of
	/// value transferred from the caller to the newly created account.
	fn instantiate(
		&mut self,
		gas_limit: Weight,
		deposit_limit: BalanceOf<Self::T>,
		code: CodeHash<Self::T>,
		value: BalanceOf<Self::T>,
		input_data: Vec<u8>,
		salt: &[u8],
	) -> Result<(AccountIdOf<Self::T>, ExecReturnValue), ExecError>;

	/// Transfer all funds to `beneficiary` and delete the contract.
	///
	/// Since this function removes the self contract eagerly, if succeeded, no further actions
	/// should be performed on this `Ext` instance.
	///
	/// This function will fail if the same contract is present on the contract
	/// call stack.
	fn terminate(&mut self, beneficiary: &AccountIdOf<Self::T>) -> DispatchResult;

	/// Transfer some amount of funds into the specified account.
	fn transfer(&mut self, to: &AccountIdOf<Self::T>, value: BalanceOf<Self::T>) -> DispatchResult;

	/// Returns the storage entry of the executing account by the given `key`.
	///
	/// Returns `None` if the `key` wasn't previously set by `set_storage` or
	/// was deleted.
	fn get_storage(&mut self, key: &Key) -> Option<Vec<u8>>;

	/// Returns `Some(len)` (in bytes) if a storage item exists at `key`.
	///
	/// Returns `None` if the `key` wasn't previously set by `set_storage` or
	/// was deleted.
	fn get_storage_size(&mut self, key: &Key) -> Option<u32>;

	/// Sets the storage entry by the given key to the specified value. If `value` is `None` then
	/// the storage entry is deleted.
	fn set_storage(
		&mut self,
		key: &Key,
		value: Option<Vec<u8>>,
		take_old: bool,
	) -> Result<WriteOutcome, DispatchError>;

	/// Returns the transient storage entry of the executing account for the given `key`.
	///
	/// Returns `None` if the `key` wasn't previously set by `set_transient_storage` or
	/// was deleted.
	fn get_transient_storage(&self, key: &Key) -> Option<Vec<u8>>;

	/// Returns `Some(len)` (in bytes) if a transient storage item exists at `key`.
	///
	/// Returns `None` if the `key` wasn't previously set by `set_transient_storage` or
	/// was deleted.
	fn get_transient_storage_size(&self, key: &Key) -> Option<u32>;

	/// Sets the transient storage entry for the given key to the specified value. If `value` is
	/// `None` then the storage entry is deleted.
	fn set_transient_storage(
		&mut self,
		key: &Key,
		value: Option<Vec<u8>>,
		take_old: bool,
	) -> Result<WriteOutcome, DispatchError>;

	/// Returns the caller.
	fn caller(&self) -> Origin<Self::T>;

	/// Check if a contract lives at the specified `address`.
	fn is_contract(&self, address: &AccountIdOf<Self::T>) -> bool;

	/// Returns the code hash of the contract for the given `address`.
	///
	/// Returns `None` if the `address` does not belong to a contract.
	fn code_hash(&self, address: &AccountIdOf<Self::T>) -> Option<CodeHash<Self::T>>;

	/// Returns the code hash of the contract being executed.
	fn own_code_hash(&mut self) -> &CodeHash<Self::T>;

	/// Check if the caller of the current contract is the origin of the whole call stack.
	///
	/// This can be checked with `is_contract(self.caller())` as well.
	/// However, this function does not require any storage lookup and therefore uses less weight.
	fn caller_is_origin(&self) -> bool;

	/// Check if the caller is origin, and this origin is root.
	fn caller_is_root(&self) -> bool;

	/// Returns a reference to the account id of the current contract.
	fn address(&self) -> &AccountIdOf<Self::T>;

	/// Returns the balance of the current contract.
	///
	/// The `value_transferred` is already added.
	fn balance(&self) -> BalanceOf<Self::T>;

	/// Returns the value transferred along with this call.
	fn value_transferred(&self) -> BalanceOf<Self::T>;

	/// Returns a reference to the timestamp of the current block
	fn now(&self) -> &MomentOf<Self::T>;

	/// Returns the minimum balance that is required for creating an account.
	fn minimum_balance(&self) -> BalanceOf<Self::T>;

	/// Deposit an event with the given topics.
	///
	/// There should not be any duplicates in `topics`.
	fn deposit_event(&mut self, topics: Vec<TopicOf<Self::T>>, data: Vec<u8>);

	/// Returns the current block number.
	fn block_number(&self) -> BlockNumberFor<Self::T>;

	/// Returns the maximum allowed size of a storage item.
	fn max_value_size(&self) -> u32;

	/// Returns the price for the specified amount of weight.
	fn get_weight_price(&self, weight: Weight) -> BalanceOf<Self::T>;

	/// Get an immutable reference to the nested gas meter.
	fn gas_meter(&self) -> &GasMeter<Self::T>;

	/// Get a mutable reference to the nested gas meter.
	fn gas_meter_mut(&mut self) -> &mut GasMeter<Self::T>;

	/// Charges `diff` from the meter.
	fn charge_storage(&mut self, diff: &Diff);

	/// Append a string to the debug buffer.
	///
	/// It is added as-is without any additional new line.
	///
	/// This is a no-op if debug message recording is disabled which is always the case
	/// when the code is executing on-chain.
	///
	/// Returns `true` if debug message recording is enabled. Otherwise `false` is returned.
	fn append_debug_buffer(&mut self, msg: &str) -> bool;

	/// Returns `true` if debug message recording is enabled. Otherwise `false` is returned.
	fn debug_buffer_enabled(&self) -> bool;

	/// Call some dispatchable and return the result.
	fn call_runtime(&self, call: <Self::T as Config>::RuntimeCall) -> DispatchResultWithPostInfo;

	/// Recovers ECDSA compressed public key based on signature and message hash.
	fn ecdsa_recover(&self, signature: &[u8; 65], message_hash: &[u8; 32]) -> Result<[u8; 33], ()>;

	/// Verify a sr25519 signature.
	fn sr25519_verify(&self, signature: &[u8; 64], message: &[u8], pub_key: &[u8; 32]) -> bool;

	/// Returns Ethereum address from the ECDSA compressed public key.
	fn ecdsa_to_eth_address(&self, pk: &[u8; 33]) -> Result<[u8; 20], ()>;

	/// Tests sometimes need to modify and inspect the contract info directly.
	#[cfg(any(test, feature = "runtime-benchmarks"))]
	fn contract_info(&mut self) -> &mut ContractInfo<Self::T>;

	/// Get a mutable reference to the transient storage.
	/// Useful in benchmarks when it is sometimes necessary to modify and inspect the transient
	/// storage directly.
	#[cfg(feature = "runtime-benchmarks")]
	fn transient_storage(&mut self) -> &mut TransientStorage<Self::T>;

	/// Sets new code hash for existing contract.
	fn set_code_hash(&mut self, hash: CodeHash<Self::T>) -> DispatchResult;

	/// Returns the number of times the specified contract exists on the call stack. Delegated calls
	/// Increment the reference count of a of a stored code by one.
	///
	/// # Errors
	///
	/// [`Error::CodeNotFound`] is returned if no stored code found having the specified
	/// `code_hash`.
	fn increment_refcount(code_hash: CodeHash<Self::T>) -> DispatchResult;

	/// Decrement the reference count of a stored code by one.
	///
	/// # Note
	///
	/// A contract whose reference count dropped to zero isn't automatically removed. A
	/// `remove_code` transaction must be submitted by the original uploader to do so.
	fn decrement_refcount(code_hash: CodeHash<Self::T>);

	/// Adds a delegate dependency to [`ContractInfo`]'s `delegate_dependencies` field.
	///
	/// This ensures that the delegated contract is not removed while it is still in use. It
	/// increases the reference count of the code hash and charges a fraction (see
	/// [`Config::CodeHashLockupDepositPercent`]) of the code deposit.
	///
	/// # Errors
	///
	/// - [`Error::MaxDelegateDependenciesReached`]
	/// - [`Error::CannotAddSelfAsDelegateDependency`]
	/// - [`Error::DelegateDependencyAlreadyExists`]
	fn lock_delegate_dependency(&mut self, code_hash: CodeHash<Self::T>) -> DispatchResult;

	/// Removes a delegate dependency from [`ContractInfo`]'s `delegate_dependencies` field.
	///
	/// This is the counterpart of [`Self::lock_delegate_dependency`]. It decreases the reference
	/// count and refunds the deposit that was charged by [`Self::lock_delegate_dependency`].
	///
	/// # Errors
	///
	/// - [`Error::DelegateDependencyNotFound`]
	fn unlock_delegate_dependency(&mut self, code_hash: &CodeHash<Self::T>) -> DispatchResult;

	/// Returns the number of locked delegate dependencies.
	///
	/// Note: Requires &mut self to access the contract info.
	fn locked_delegate_dependencies_count(&mut self) -> usize;

	/// Check if running in read-only context.
	fn is_read_only(&self) -> bool;
}

/// Describes the different functions that can be exported by an [`Executable`].
#[derive(
	Copy,
	Clone,
	PartialEq,
	Eq,
	sp_core::RuntimeDebug,
	codec::Decode,
	codec::Encode,
	codec::MaxEncodedLen,
	scale_info::TypeInfo,
)]
pub enum ExportedFunction {
	/// The constructor function which is executed on deployment of a contract.
	Constructor,
	/// The function which is executed when a contract is called.
	Call,
}

/// A trait that represents something that can be executed.
///
/// In the on-chain environment this would be represented by a wasm module. This trait exists in
/// order to be able to mock the wasm logic for testing.
pub trait Executable<T: Config>: Sized {
	/// Load the executable from storage.
	///
	/// # Note
	/// Charges size base load weight from the gas meter.
	fn from_storage(
		code_hash: CodeHash<T>,
		gas_meter: &mut GasMeter<T>,
	) -> Result<Self, DispatchError>;

	/// Execute the specified exported function and return the result.
	///
	/// When the specified function is `Constructor` the executable is stored and its
	/// refcount incremented.
	///
	/// # Note
	///
	/// This functions expects to be executed in a storage transaction that rolls back
	/// all of its emitted storage changes.
	fn execute<E: Ext<T = T>>(
		self,
		ext: &mut E,
		function: ExportedFunction,
		input_data: Vec<u8>,
	) -> ExecResult;

	/// The code info of the executable.
	fn code_info(&self) -> &CodeInfo<T>;

	/// The code hash of the executable.
	fn code_hash(&self) -> &CodeHash<T>;
}

/// The complete call stack of a contract execution.
///
/// The call stack is initiated by either a signed origin or one of the contract RPC calls.
/// This type implements `Ext` and by that exposes the business logic of contract execution to
/// the runtime module which interfaces with the contract (the wasm blob) itself.
pub struct Stack<'a, T: Config, E> {
	/// The origin that initiated the call stack. It could either be a Signed plain account that
	/// holds an account id or Root.
	///
	/// # Note
	///
	/// Please note that it is possible that the id of a Signed origin belongs to a contract rather
	/// than a plain account when being called through one of the contract RPCs where the
	/// client can freely choose the origin. This usually makes no sense but is still possible.
	origin: Origin<T>,
	/// The gas meter where costs are charged to.
	gas_meter: &'a mut GasMeter<T>,
	/// The storage meter makes sure that the storage deposit limit is obeyed.
	storage_meter: &'a mut storage::meter::Meter<T>,
	/// The timestamp at the point of call stack instantiation.
	timestamp: MomentOf<T>,
	/// The block number at the time of call stack instantiation.
	block_number: BlockNumberFor<T>,
	/// The actual call stack. One entry per nested contract called/instantiated.
	/// This does **not** include the [`Self::first_frame`].
	frames: BoundedVec<Frame<T>, ConstU32<{ limits::CALL_STACK_DEPTH }>>,
	/// Statically guarantee that each call stack has at least one frame.
	first_frame: Frame<T>,
	/// A text buffer used to output human readable information.
	///
	/// All the bytes added to this field should be valid UTF-8. The buffer has no defined
	/// structure and is intended to be shown to users as-is for debugging purposes.
	debug_message: Option<&'a mut DebugBuffer>,
	/// Transient storage used to store data, which is kept for the duration of a transaction.
	transient_storage: TransientStorage<T>,
	/// No executable is held by the struct but influences its behaviour.
	_phantom: PhantomData<E>,
}

/// Represents one entry in the call stack.
///
/// For each nested contract call or instantiate one frame is created. It holds specific
/// information for the said call and caches the in-storage `ContractInfo` data structure.
struct Frame<T: Config> {
	/// The account id of the executing contract.
	account_id: T::AccountId,
	/// The cached in-storage data of the contract.
	contract_info: CachedContract<T>,
	/// The amount of balance transferred by the caller as part of the call.
	value_transferred: BalanceOf<T>,
	/// Determines whether this is a call or instantiate frame.
	entry_point: ExportedFunction,
	/// The gas meter capped to the supplied gas limit.
	nested_gas: GasMeter<T>,
	/// The storage meter for the individual call.
	nested_storage: storage::meter::NestedMeter<T>,
	/// If `false` the contract enabled its defense against reentrance attacks.
	allows_reentry: bool,
	/// If `true` subsequent calls cannot modify storage.
	read_only: bool,
	/// The caller of the currently executing frame which was spawned by `delegate_call`.
	delegate_caller: Option<Origin<T>>,
}

/// Used in a delegate call frame arguments in order to override the executable and caller.
struct DelegatedCall<T: Config, E> {
	/// The executable which is run instead of the contracts own `executable`.
	executable: E,
	/// The caller of the contract.
	caller: Origin<T>,
}

/// Parameter passed in when creating a new `Frame`.
///
/// It determines whether the new frame is for a call or an instantiate.
enum FrameArgs<'a, T: Config, E> {
	Call {
		/// The account id of the contract that is to be called.
		dest: T::AccountId,
		/// If `None` the contract info needs to be reloaded from storage.
		cached_info: Option<ContractInfo<T>>,
		/// This frame was created by `seal_delegate_call` and hence uses different code than
		/// what is stored at [`Self::Call::dest`]. Its caller ([`DelegatedCall::caller`]) is the
		/// account which called the caller contract
		delegated_call: Option<DelegatedCall<T, E>>,
	},
	Instantiate {
		/// The contract or signed origin which instantiates the new contract.
		sender: T::AccountId,
		/// The executable whose `deploy` function is run.
		executable: E,
		/// A salt used in the contract address derivation of the new contract.
		salt: &'a [u8],
		/// The input data is used in the contract address derivation of the new contract.
		input_data: &'a [u8],
	},
}

/// Describes the different states of a contract as contained in a `Frame`.
enum CachedContract<T: Config> {
	/// The cached contract is up to date with the in-storage value.
	Cached(ContractInfo<T>),
	/// A recursive call into the same contract did write to the contract info.
	///
	/// In this case the cached contract is stale and needs to be reloaded from storage.
	Invalidated,
	/// The current contract executed `terminate` and removed the contract.
	///
	/// In this case a reload is neither allowed nor possible. Please note that recursive
	/// calls cannot remove a contract as this is checked and denied.
	Terminated,
}

impl<T: Config> CachedContract<T> {
	/// Return `Some(ContractInfo)` if the contract is in cached state. `None` otherwise.
	fn into_contract(self) -> Option<ContractInfo<T>> {
		if let CachedContract::Cached(contract) = self {
			Some(contract)
		} else {
			None
		}
	}

	/// Return `Some(&mut ContractInfo)` if the contract is in cached state. `None` otherwise.
	fn as_contract(&mut self) -> Option<&mut ContractInfo<T>> {
		if let CachedContract::Cached(contract) = self {
			Some(contract)
		} else {
			None
		}
	}
}

impl<T: Config> Frame<T> {
	/// Return the `contract_info` of the current contract.
	fn contract_info(&mut self) -> &mut ContractInfo<T> {
		self.contract_info.get(&self.account_id)
	}

	/// Terminate and return the `contract_info` of the current contract.
	///
	/// # Note
	///
	/// Under no circumstances the contract is allowed to access the `contract_info` after
	/// a call to this function. This would constitute a programming error in the exec module.
	fn terminate(&mut self) -> ContractInfo<T> {
		self.contract_info.terminate(&self.account_id)
	}
}

/// Extract the contract info after loading it from storage.
///
/// This assumes that `load` was executed before calling this macro.
macro_rules! get_cached_or_panic_after_load {
	($c:expr) => {{
		if let CachedContract::Cached(contract) = $c {
			contract
		} else {
			panic!(
				"It is impossible to remove a contract that is on the call stack;\
				See implementations of terminate;\
				Therefore fetching a contract will never fail while using an account id
				that is currently active on the call stack;\
				qed"
			);
		}
	}};
}

/// Same as [`Stack::top_frame`].
///
/// We need this access as a macro because sometimes hiding the lifetimes behind
/// a function won't work out.
macro_rules! top_frame {
	($stack:expr) => {
		$stack.frames.last().unwrap_or(&$stack.first_frame)
	};
}

/// Same as [`Stack::top_frame_mut`].
///
/// We need this access as a macro because sometimes hiding the lifetimes behind
/// a function won't work out.
macro_rules! top_frame_mut {
	($stack:expr) => {
		$stack.frames.last_mut().unwrap_or(&mut $stack.first_frame)
	};
}

impl<T: Config> CachedContract<T> {
	/// Load the `contract_info` from storage if necessary.
	fn load(&mut self, account_id: &T::AccountId) {
		if let CachedContract::Invalidated = self {
			let contract = <ContractInfoOf<T>>::get(&account_id);
			if let Some(contract) = contract {
				*self = CachedContract::Cached(contract);
			}
		}
	}

	/// Return the cached contract_info.
	fn get(&mut self, account_id: &T::AccountId) -> &mut ContractInfo<T> {
		self.load(account_id);
		get_cached_or_panic_after_load!(self)
	}

	/// Terminate and return the contract info.
	fn terminate(&mut self, account_id: &T::AccountId) -> ContractInfo<T> {
		self.load(account_id);
		get_cached_or_panic_after_load!(mem::replace(self, Self::Terminated))
	}
}

impl<'a, T, E> Stack<'a, T, E>
where
	T: Config,
	E: Executable<T>,
{
	/// Create and run a new call stack by calling into `dest`.
	///
	/// # Note
	///
	/// `debug_message` should only ever be set to `Some` when executing as an RPC because
	/// it adds allocations and could be abused to drive the runtime into an OOM panic.
	///
	/// # Return Value
	///
	/// Result<(ExecReturnValue, CodeSize), (ExecError, CodeSize)>
	pub fn run_call(
		origin: Origin<T>,
		dest: T::AccountId,
		gas_meter: &'a mut GasMeter<T>,
		storage_meter: &'a mut storage::meter::Meter<T>,
		value: BalanceOf<T>,
		input_data: Vec<u8>,
		debug_message: Option<&'a mut DebugBuffer>,
	) -> Result<ExecReturnValue, ExecError> {
		let (mut stack, executable) = Self::new(
			FrameArgs::Call { dest, cached_info: None, delegated_call: None },
			origin,
			gas_meter,
			storage_meter,
			value,
			debug_message,
		)?;
		stack.run(executable, input_data)
	}

	/// Create and run a new call stack by instantiating a new contract.
	///
	/// # Note
	///
	/// `debug_message` should only ever be set to `Some` when executing as an RPC because
	/// it adds allocations and could be abused to drive the runtime into an OOM panic.
	///
	/// # Return Value
	///
	/// Result<(NewContractAccountId, ExecReturnValue), ExecError)>
	pub fn run_instantiate(
		origin: T::AccountId,
		executable: E,
		gas_meter: &'a mut GasMeter<T>,
		storage_meter: &'a mut storage::meter::Meter<T>,
		value: BalanceOf<T>,
		input_data: Vec<u8>,
		salt: &[u8],
		debug_message: Option<&'a mut DebugBuffer>,
	) -> Result<(T::AccountId, ExecReturnValue), ExecError> {
		let (mut stack, executable) = Self::new(
			FrameArgs::Instantiate {
				sender: origin.clone(),
				executable,
				salt,
				input_data: input_data.as_ref(),
			},
			Origin::from_account_id(origin),
			gas_meter,
			storage_meter,
			value,
			debug_message,
		)?;
		let account_id = stack.top_frame().account_id.clone();
		stack.run(executable, input_data).map(|ret| (account_id, ret))
	}

	#[cfg(all(feature = "runtime-benchmarks", feature = "riscv"))]
	pub fn bench_new_call(
		dest: T::AccountId,
		origin: Origin<T>,
		gas_meter: &'a mut GasMeter<T>,
		storage_meter: &'a mut storage::meter::Meter<T>,
		value: BalanceOf<T>,
		debug_message: Option<&'a mut DebugBuffer>,
	) -> (Self, E) {
		Self::new(
			FrameArgs::Call { dest, cached_info: None, delegated_call: None },
			origin,
			gas_meter,
			storage_meter,
			value,
			debug_message,
		)
		.unwrap()
	}

	/// Create a new call stack.
	fn new(
		args: FrameArgs<T, E>,
		origin: Origin<T>,
		gas_meter: &'a mut GasMeter<T>,
		storage_meter: &'a mut storage::meter::Meter<T>,
		value: BalanceOf<T>,
		debug_message: Option<&'a mut DebugBuffer>,
	) -> Result<(Self, E), ExecError> {
		let (first_frame, executable) = Self::new_frame(
			args,
			value,
			gas_meter,
			Weight::zero(),
			storage_meter,
			BalanceOf::<T>::zero(),
			false,
		)?;

		let stack = Self {
			origin,
			gas_meter,
			storage_meter,
			timestamp: T::Time::now(),
			block_number: <frame_system::Pallet<T>>::block_number(),
			first_frame,
			frames: Default::default(),
			debug_message,
			transient_storage: TransientStorage::new(limits::TRANSIENT_STORAGE_BYTES),
			_phantom: Default::default(),
		};

		Ok((stack, executable))
	}

	/// Construct a new frame.
	///
	/// This does not take `self` because when constructing the first frame `self` is
	/// not initialized, yet.
	fn new_frame<S: storage::meter::State + Default + Debug>(
		frame_args: FrameArgs<T, E>,
		value_transferred: BalanceOf<T>,
		gas_meter: &mut GasMeter<T>,
		gas_limit: Weight,
		storage_meter: &mut storage::meter::GenericMeter<T, S>,
		deposit_limit: BalanceOf<T>,
		read_only: bool,
	) -> Result<(Frame<T>, E), ExecError> {
		let (account_id, contract_info, executable, delegate_caller, entry_point) = match frame_args
		{
			FrameArgs::Call { dest, cached_info, delegated_call } => {
				let contract = if let Some(contract) = cached_info {
					contract
				} else {
					<ContractInfoOf<T>>::get(&dest).ok_or(<Error<T>>::ContractNotFound)?
				};

				let (executable, delegate_caller) =
					if let Some(DelegatedCall { executable, caller }) = delegated_call {
						(executable, Some(caller))
					} else {
						(E::from_storage(contract.code_hash, gas_meter)?, None)
					};

				(dest, contract, executable, delegate_caller, ExportedFunction::Call)
			},
			FrameArgs::Instantiate { sender, executable, salt, input_data } => {
				let account_id = Contracts::<T>::contract_address(
					&sender,
					&executable.code_hash(),
					input_data,
					salt,
				);
				let contract = ContractInfo::new(
					&account_id,
					<System<T>>::account_nonce(&sender),
					*executable.code_hash(),
				)?;
				(account_id, contract, executable, None, ExportedFunction::Constructor)
			},
		};

		let frame = Frame {
			delegate_caller,
			value_transferred,
			contract_info: CachedContract::Cached(contract_info),
			account_id,
			entry_point,
			nested_gas: gas_meter.nested(gas_limit),
			nested_storage: storage_meter.nested(deposit_limit),
			allows_reentry: true,
			read_only,
		};

		Ok((frame, executable))
	}

	/// Create a subsequent nested frame.
	fn push_frame(
		&mut self,
		frame_args: FrameArgs<T, E>,
		value_transferred: BalanceOf<T>,
		gas_limit: Weight,
		deposit_limit: BalanceOf<T>,
		read_only: bool,
	) -> Result<E, ExecError> {
		if self.frames.len() as u32 == limits::CALL_STACK_DEPTH {
			return Err(Error::<T>::MaxCallDepthReached.into())
		}

		// We need to make sure that changes made to the contract info are not discarded.
		// See the `in_memory_changes_not_discarded` test for more information.
		// We do not store on instantiate because we do not allow to call into a contract
		// from its own constructor.
		let frame = self.top_frame();
		if let (CachedContract::Cached(contract), ExportedFunction::Call) =
			(&frame.contract_info, frame.entry_point)
		{
			<ContractInfoOf<T>>::insert(frame.account_id.clone(), contract.clone());
		}

		let frame = top_frame_mut!(self);
		let nested_gas = &mut frame.nested_gas;
		let nested_storage = &mut frame.nested_storage;
		let (frame, executable) = Self::new_frame(
			frame_args,
			value_transferred,
			nested_gas,
			gas_limit,
			nested_storage,
			deposit_limit,
			read_only,
		)?;
		self.frames.try_push(frame).map_err(|_| Error::<T>::MaxCallDepthReached)?;
		Ok(executable)
	}

	/// Run the current (top) frame.
	///
	/// This can be either a call or an instantiate.
	fn run(&mut self, executable: E, input_data: Vec<u8>) -> Result<ExecReturnValue, ExecError> {
		let frame = self.top_frame();
		let entry_point = frame.entry_point;
		let delegated_code_hash =
			if frame.delegate_caller.is_some() { Some(*executable.code_hash()) } else { None };

		self.transient_storage.start_transaction();

		let do_transaction = || {
			// We need to charge the storage deposit before the initial transfer so that
			// it can create the account in case the initial transfer is < ed.
			if entry_point == ExportedFunction::Constructor {
				// Root origin can't be used to instantiate a contract, so it is safe to assume that
				// if we reached this point the origin has an associated account.
				let origin = &self.origin.account_id()?;
				let frame = top_frame_mut!(self);
				frame.nested_storage.charge_instantiate(
					origin,
					&frame.account_id,
					frame.contract_info.get(&frame.account_id),
					executable.code_info(),
				)?;
				// Needs to be incremented before calling into the code so that it is visible
				// in case of recursion.
				<System<T>>::inc_account_nonce(self.caller().account_id()?);
			}

			// Every non delegate call or instantiate also optionally transfers the balance.
			self.initial_transfer()?;

			let contract_address = &top_frame!(self).account_id;

			let call_span = T::Debug::new_call_span(contract_address, entry_point, &input_data);

			let output = T::Debug::intercept_call(contract_address, entry_point, &input_data)
				.unwrap_or_else(|| {
					executable
						.execute(self, entry_point, input_data)
						.map_err(|e| ExecError { error: e.error, origin: ErrorOrigin::Callee })
				})?;

			call_span.after_call(&output);

			// Avoid useless work that would be reverted anyways.
			if output.did_revert() {
				return Ok(output)
			}

			// Storage limit is normally enforced as late as possible (when the last frame returns)
			// so that the ordering of storage accesses does not matter.
			// (However, if a special limit was set for a sub-call, it should be enforced right
			// after the sub-call returned. See below for this case of enforcement).
			if self.frames.is_empty() {
				let frame = &mut self.first_frame;
				frame.contract_info.load(&frame.account_id);
				let contract = frame.contract_info.as_contract();
				frame.nested_storage.enforce_limit(contract)?;
			}

			let frame = self.top_frame();
			let account_id = &frame.account_id.clone();
			match (entry_point, delegated_code_hash) {
				(ExportedFunction::Constructor, _) => {
					// It is not allowed to terminate a contract inside its constructor.
					if matches!(frame.contract_info, CachedContract::Terminated) {
						return Err(Error::<T>::TerminatedInConstructor.into())
					}

					// If a special limit was set for the sub-call, we enforce it here.
					// This is needed because contract constructor might write to storage.
					// The sub-call will be rolled back in case the limit is exhausted.
					let frame = self.top_frame_mut();
					let contract = frame.contract_info.as_contract();
					frame.nested_storage.enforce_subcall_limit(contract)?;

					let caller = self.caller().account_id()?.clone();

					// Deposit an instantiation event.