From 24c41f10bb29857cc7fcb316d47ac055c15537f7 Mon Sep 17 00:00:00 2001
From: Cyrill Leutwiler <cyrill@parity.io>
Date: Fri, 1 Sep 2023 14:33:15 +0200
Subject: [PATCH] Contracts: `seal0::balance` should return the free balance
(#1254)
---
.../frame/contracts/fixtures/balance.wat | 42 ++++++++++++++++
substrate/frame/contracts/fixtures/drain.wat | 35 +++++++++++--
substrate/frame/contracts/src/exec.rs | 8 ++-
substrate/frame/contracts/src/tests.rs | 50 +++++++++++++++++++
4 files changed, 128 insertions(+), 7 deletions(-)
create mode 100644 substrate/frame/contracts/fixtures/balance.wat
diff --git a/substrate/frame/contracts/fixtures/balance.wat b/substrate/frame/contracts/fixtures/balance.wat
new file mode 100644
index 00000000000..d86d5c4b1c6
--- /dev/null
+++ b/substrate/frame/contracts/fixtures/balance.wat
@@ -0,0 +1,42 @@
+(module
+ (import "seal0" "seal_balance" (func $seal_balance (param i32 i32)))
+ (import "env" "memory" (memory 1 1))
+
+ ;; [0, 8) reserved for $seal_balance output
+
+ ;; [8, 16) length of the buffer for $seal_balance
+ (data (i32.const 8) "\08")
+
+ ;; [16, inf) zero initialized
+
+ (func $assert (param i32)
+ (block $ok
+ (br_if $ok
+ (get_local 0)
+ )
+ (unreachable)
+ )
+ )
+
+ (func (export "deploy"))
+
+ (func (export "call")
+ (call $seal_balance (i32.const 0) (i32.const 8))
+
+ ;; Balance should be encoded as a u64.
+ (call $assert
+ (i32.eq
+ (i32.load (i32.const 8))
+ (i32.const 8)
+ )
+ )
+
+ ;; Assert the free balance to be zero.
+ (call $assert
+ (i64.eq
+ (i64.load (i32.const 0))
+ (i64.const 0)
+ )
+ )
+ )
+)
diff --git a/substrate/frame/contracts/fixtures/drain.wat b/substrate/frame/contracts/fixtures/drain.wat
index 9f126898fac..cb8ff0aed61 100644
--- a/substrate/frame/contracts/fixtures/drain.wat
+++ b/substrate/frame/contracts/fixtures/drain.wat
@@ -1,14 +1,20 @@
(module
(import "seal0" "seal_balance" (func $seal_balance (param i32 i32)))
+ (import "seal0" "seal_minimum_balance" (func $seal_minimum_balance (param i32 i32)))
(import "seal0" "seal_transfer" (func $seal_transfer (param i32 i32 i32 i32) (result i32)))
(import "env" "memory" (memory 1 1))
;; [0, 8) reserved for $seal_balance output
- ;; [8, 16) length of the buffer
+ ;; [8, 16) length of the buffer for $seal_balance
(data (i32.const 8) "\08")
- ;; [16, inf) zero initialized
+ ;; [16, 24) reserved for $seal_minimum_balance
+
+ ;; [24, 32) length of the buffer for $seal_minimum_balance
+ (data (i32.const 24) "\08")
+
+ ;; [32, inf) zero initialized
(func $assert (param i32)
(block $ok
@@ -33,13 +39,32 @@
)
)
- ;; Try to self-destruct by sending full balance to the 0 address.
+ ;; Get the minimum balance.
+ (call $seal_minimum_balance (i32.const 16) (i32.const 24))
+
+ ;; Minimum balance should be encoded as a u64.
+ (call $assert
+ (i32.eq
+ (i32.load (i32.const 24))
+ (i32.const 8)
+ )
+ )
+
+ ;; Make the transferred value exceed the balance by adding the minimum balance.
+ (i64.store (i32.const 0)
+ (i64.add
+ (i64.load (i32.const 0))
+ (i64.load (i32.const 16))
+ )
+ )
+
+ ;; Try to self-destruct by sending more balance to the 0 address.
;; The call will fail because a contract transfer has a keep alive requirement
(call $assert
(i32.eq
(call $seal_transfer
- (i32.const 16) ;; Pointer to destination address
- (i32.const 32) ;; Length of destination address
+ (i32.const 32) ;; Pointer to destination address
+ (i32.const 48) ;; Length of destination address
(i32.const 0) ;; Pointer to the buffer with value to transfer
(i32.const 8) ;; Length of the buffer with value to transfer
)
diff --git a/substrate/frame/contracts/src/exec.rs b/substrate/frame/contracts/src/exec.rs
index 38c15a807c5..894667280b7 100644
--- a/substrate/frame/contracts/src/exec.rs
+++ b/substrate/frame/contracts/src/exec.rs
@@ -30,7 +30,7 @@ use frame_support::{
storage::{with_transaction, TransactionOutcome},
traits::{
fungible::{Inspect, Mutate},
- tokens::Preservation,
+ tokens::{Fortitude, Preservation},
Contains, OriginTrait, Randomness, Time,
},
weights::Weight,
@@ -1368,7 +1368,11 @@ where
}
fn balance(&self) -> BalanceOf<T> {
- T::Currency::balance(&self.top_frame().account_id)
+ T::Currency::reducible_balance(
+ &self.top_frame().account_id,
+ Preservation::Preserve,
+ Fortitude::Polite,
+ )
}
fn value_transferred(&self) -> BalanceOf<T> {
diff --git a/substrate/frame/contracts/src/tests.rs b/substrate/frame/contracts/src/tests.rs
index 9d03a29b038..0c0a2f7f932 100644
--- a/substrate/frame/contracts/src/tests.rs
+++ b/substrate/frame/contracts/src/tests.rs
@@ -5891,3 +5891,53 @@ fn root_cannot_instantiate() {
);
});
}
+
+#[test]
+fn balance_api_returns_free_balance() {
+ let (wasm, _code_hash) = compile_module::<Test>("balance").unwrap();
+ ExtBuilder::default().existential_deposit(200).build().execute_with(|| {
+ let _ = <Test as Config>::Currency::set_balance(&ALICE, 1_000_000);
+
+ // Instantiate the BOB contract without any extra balance.
+ let addr = Contracts::bare_instantiate(
+ ALICE,
+ 0,
+ GAS_LIMIT,
+ None,
+ Code::Upload(wasm.to_vec()),
+ vec![],
+ vec![],
+ DebugInfo::Skip,
+ CollectEvents::Skip,
+ )
+ .result
+ .unwrap()
+ .account_id;
+
+ let value = 0;
+ // Call BOB which makes it call the balance runtime API.
+ // The contract code asserts that the returned balance is 0.
+ assert_ok!(Contracts::call(
+ RuntimeOrigin::signed(ALICE),
+ addr.clone(),
+ value,
+ GAS_LIMIT,
+ None,
+ vec![]
+ ));
+
+ let value = 1;
+ // Calling with value will trap the contract.
+ assert_err_ignore_postinfo!(
+ Contracts::call(
+ RuntimeOrigin::signed(ALICE),
+ addr.clone(),
+ value,
+ GAS_LIMIT,
+ None,
+ vec![]
+ ),
+ <Error<Test>>::ContractTrapped
+ );
+ });
+}
--
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