From d859734ed9ca34407b83747563fd77efa9fdafaf Mon Sep 17 00:00:00 2001
From: Shaun Wang <spxwang@gmail.com>
Date: Wed, 10 Mar 2021 03:46:30 +1300
Subject: [PATCH] Replace XCM `Error::Undefined` usage (#2580)
* Replace undefined error in currency adapter.
* Update tranact asset errors.
* Update TransactAsset trait documentations.
* Update currency adapter error documentation.
---
polkadot/xcm/src/v0/traits.rs | 1 +
.../xcm/xcm-builder/src/currency_adapter.rs | 54 +++++++++++++++----
polkadot/xcm/xcm-executor/src/traits.rs | 6 ++-
3 files changed, 51 insertions(+), 10 deletions(-)
diff --git a/polkadot/xcm/src/v0/traits.rs b/polkadot/xcm/src/v0/traits.rs
index eafeca8661c..542db15dd03 100644
--- a/polkadot/xcm/src/v0/traits.rs
+++ b/polkadot/xcm/src/v0/traits.rs
@@ -37,6 +37,7 @@ pub enum Error {
FailedToDecode,
BadOrigin,
ExceedsMaxMessageSize,
+ FailedToTransactAsset(#[codec(skip)] &'static str),
}
impl From<()> for Error {
diff --git a/polkadot/xcm/xcm-builder/src/currency_adapter.rs b/polkadot/xcm/xcm-builder/src/currency_adapter.rs
index 09b61ab6bb5..7883d5959d7 100644
--- a/polkadot/xcm/xcm-builder/src/currency_adapter.rs
+++ b/polkadot/xcm/xcm-builder/src/currency_adapter.rs
@@ -15,11 +15,33 @@
// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
use sp_std::{result, convert::TryInto, marker::PhantomData};
-use xcm::v0::{Error, Result, MultiAsset, MultiLocation};
+use xcm::v0::{Error as XcmError, Result, MultiAsset, MultiLocation};
use sp_arithmetic::traits::SaturatedConversion;
use frame_support::traits::{ExistenceRequirement::AllowDeath, WithdrawReasons};
use xcm_executor::traits::{MatchesFungible, LocationConversion, TransactAsset};
+/// Asset transaction errors.
+enum Error {
+ /// Asset not found.
+ AssetNotFound,
+ /// `MultiLocation` to `AccountId` Conversion failed.
+ AccountIdConversionFailed,
+ /// `u128` amount to currency `Balance` conversion failed.
+ AmountToBalanceConversionFailed,
+}
+
+impl From<Error> for XcmError {
+ fn from(e: Error) -> Self {
+ match e {
+ Error::AssetNotFound => XcmError::FailedToTransactAsset("AssetNotFound"),
+ Error::AccountIdConversionFailed =>
+ XcmError::FailedToTransactAsset("AccountIdConversionFailed"),
+ Error::AmountToBalanceConversionFailed =>
+ XcmError::FailedToTransactAsset("AmountToBalanceConversionFailed"),
+ }
+ }
+}
+
pub struct CurrencyAdapter<Currency, Matcher, AccountIdConverter, AccountId>(
PhantomData<Currency>,
PhantomData<Matcher>,
@@ -36,19 +58,33 @@ impl<
fn deposit_asset(what: &MultiAsset, who: &MultiLocation) -> Result {
// Check we handle this asset.
- let amount: u128 = Matcher::matches_fungible(&what).ok_or(())?.saturated_into();
- let who = AccountIdConverter::from_location(who).ok_or(())?;
- let balance_amount = amount.try_into().map_err(|_| ())?;
+ let amount: u128 = Matcher::matches_fungible(&what)
+ .ok_or(XcmError::from(Error::AssetNotFound))?
+ .saturated_into();
+ let who = AccountIdConverter::from_location(who)
+ .ok_or(XcmError::from(Error::AccountIdConversionFailed))?;
+ let balance_amount = amount
+ .try_into()
+ .map_err(|_| XcmError::from(Error::AmountToBalanceConversionFailed))?;
let _imbalance = Currency::deposit_creating(&who, balance_amount);
Ok(())
}
- fn withdraw_asset(what: &MultiAsset, who: &MultiLocation) -> result::Result<MultiAsset, Error> {
+ fn withdraw_asset(
+ what: &MultiAsset,
+ who: &MultiLocation
+ ) -> result::Result<MultiAsset, XcmError> {
// Check we handle this asset.
- let amount: u128 = Matcher::matches_fungible(&what).ok_or(())?.saturated_into();
- let who = AccountIdConverter::from_location(who).ok_or(())?;
- let balance_amount = amount.try_into().map_err(|_| ())?;
- Currency::withdraw(&who, balance_amount, WithdrawReasons::TRANSFER, AllowDeath).map_err(|_| ())?;
+ let amount: u128 = Matcher::matches_fungible(&what)
+ .ok_or(XcmError::from(Error::AssetNotFound))?
+ .saturated_into();
+ let who = AccountIdConverter::from_location(who)
+ .ok_or(XcmError::from(Error::AccountIdConversionFailed))?;
+ let balance_amount = amount
+ .try_into()
+ .map_err(|_| XcmError::from(Error::AmountToBalanceConversionFailed))?;
+ Currency::withdraw(&who, balance_amount, WithdrawReasons::TRANSFER, AllowDeath)
+ .map_err(|e| XcmError::FailedToTransactAsset(e.into()))?;
Ok(what.clone())
}
}
diff --git a/polkadot/xcm/xcm-executor/src/traits.rs b/polkadot/xcm/xcm-executor/src/traits.rs
index d01791dfa23..a5fc2040f66 100644
--- a/polkadot/xcm/xcm-executor/src/traits.rs
+++ b/polkadot/xcm/xcm-executor/src/traits.rs
@@ -57,15 +57,19 @@ impl<T: Get<(MultiAsset, MultiLocation)>> FilterAssetLocation for Case<T> {
/// different ways.
pub trait TransactAsset {
/// Deposit the `what` asset into the account of `who`.
+ ///
+ /// Implementations should return `XcmError::FailedToTransactAsset` if deposit failed.
fn deposit_asset(what: &MultiAsset, who: &MultiLocation) -> XcmResult;
/// Withdraw the given asset from the consensus system. Return the actual asset withdrawn. In
/// the case of `what` being a wildcard, this may be something more specific.
+ ///
+ /// Implementations should return `XcmError::FailedToTransactAsset` if withdraw failed.
fn withdraw_asset(what: &MultiAsset, who: &MultiLocation) -> Result<MultiAsset, XcmError>;
/// Move an `asset` `from` one location in `to` another location.
///
- /// Undefined if from account doesn't own this asset.
+ /// Returns `XcmError::FailedToTransactAsset` if transfer failed.
fn transfer_asset(asset: &MultiAsset, from: &MultiLocation, to: &MultiLocation) -> Result<MultiAsset, XcmError> {
let withdrawn = Self::withdraw_asset(asset, from)?;
Self::deposit_asset(&withdrawn, to)?;
--
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