From 389b8f1698f696e880d122b2cf2338441b37d058 Mon Sep 17 00:00:00 2001
From: Hero Bird <robin.freyler@gmail.com>
Date: Thu, 23 Jan 2020 15:13:49 +0100
Subject: [PATCH] [contracts] Add ext_tombstone_deposit (#4722)
* [contracts] add ext_tombstone_deposit
* [contracts] update tombstone_deposit docs
---
substrate/frame/contracts/src/exec.rs | 7 ++
substrate/frame/contracts/src/lib.rs | 2 +
substrate/frame/contracts/src/wasm/mod.rs | 66 +++++++++++++++++++
substrate/frame/contracts/src/wasm/runtime.rs | 17 +++++
4 files changed, 92 insertions(+)
diff --git a/substrate/frame/contracts/src/exec.rs b/substrate/frame/contracts/src/exec.rs
index 9d786c320b5..ceaccd35cb6 100644
--- a/substrate/frame/contracts/src/exec.rs
+++ b/substrate/frame/contracts/src/exec.rs
@@ -161,6 +161,9 @@ pub trait Ext {
/// Returns the minimum balance that is required for creating an account.
fn minimum_balance(&self) -> BalanceOf<Self::T>;
+ /// Returns the deposit required to create a tombstone upon contract eviction.
+ fn tombstone_deposit(&self) -> BalanceOf<Self::T>;
+
/// Returns a random number for the current block with the given subject.
fn random(&self, subject: &[u8]) -> SeedOf<Self::T>;
@@ -779,6 +782,10 @@ where
self.ctx.config.existential_deposit
}
+ fn tombstone_deposit(&self) -> BalanceOf<T> {
+ self.ctx.config.tombstone_deposit
+ }
+
fn deposit_event(&mut self, topics: Vec<T::Hash>, data: Vec<u8>) {
self.ctx.deferred.push(DeferredAction::DepositEvent {
topics,
diff --git a/substrate/frame/contracts/src/lib.rs b/substrate/frame/contracts/src/lib.rs
index 40ce86518a5..d16462d8bf5 100644
--- a/substrate/frame/contracts/src/lib.rs
+++ b/substrate/frame/contracts/src/lib.rs
@@ -969,6 +969,7 @@ impl<T: Trait> OnFreeBalanceZero<T::AccountId> for Module<T> {
pub struct Config<T: Trait> {
pub schedule: Schedule,
pub existential_deposit: BalanceOf<T>,
+ pub tombstone_deposit: BalanceOf<T>,
pub max_depth: u32,
pub max_value_size: u32,
pub contract_account_instantiate_fee: BalanceOf<T>,
@@ -981,6 +982,7 @@ impl<T: Trait> Config<T> {
Config {
schedule: <Module<T>>::current_schedule(),
existential_deposit: T::Currency::minimum_balance(),
+ tombstone_deposit: T::TombstoneDeposit::get(),
max_depth: T::MaxDepth::get(),
max_value_size: T::MaxValueSize::get(),
contract_account_instantiate_fee: T::ContractFee::get(),
diff --git a/substrate/frame/contracts/src/wasm/mod.rs b/substrate/frame/contracts/src/wasm/mod.rs
index 60402cf3a09..1ea2067a8d2 100644
--- a/substrate/frame/contracts/src/wasm/mod.rs
+++ b/substrate/frame/contracts/src/wasm/mod.rs
@@ -299,6 +299,10 @@ mod tests {
666
}
+ fn tombstone_deposit(&self) -> u64 {
+ 16
+ }
+
fn random(&self, subject: &[u8]) -> H256 {
H256::from_slice(subject)
}
@@ -397,6 +401,9 @@ mod tests {
fn minimum_balance(&self) -> u64 {
(**self).minimum_balance()
}
+ fn tombstone_deposit(&self) -> u64 {
+ (**self).tombstone_deposit()
+ }
fn random(&self, subject: &[u8]) -> H256 {
(**self).random(subject)
}
@@ -1271,6 +1278,65 @@ mod tests {
).unwrap();
}
+ const CODE_TOMBSTONE_DEPOSIT: &str = r#"
+(module
+ (import "env" "ext_tombstone_deposit" (func $ext_tombstone_deposit))
+ (import "env" "ext_scratch_size" (func $ext_scratch_size (result i32)))
+ (import "env" "ext_scratch_read" (func $ext_scratch_read (param i32 i32 i32)))
+ (import "env" "memory" (memory 1 1))
+
+ (func $assert (param i32)
+ (block $ok
+ (br_if $ok
+ (get_local 0)
+ )
+ (unreachable)
+ )
+ )
+
+ (func (export "call")
+ (call $ext_tombstone_deposit)
+
+ ;; assert $ext_scratch_size == 8
+ (call $assert
+ (i32.eq
+ (call $ext_scratch_size)
+ (i32.const 8)
+ )
+ )
+
+ ;; copy contents of the scratch buffer into the contract's memory.
+ (call $ext_scratch_read
+ (i32.const 8) ;; Pointer in memory to the place where to copy.
+ (i32.const 0) ;; Offset from the start of the scratch buffer.
+ (i32.const 8) ;; Count of bytes to copy.
+ )
+
+ ;; assert that contents of the buffer is equal to the i64 value of 16.
+ (call $assert
+ (i64.eq
+ (i64.load
+ (i32.const 8)
+ )
+ (i64.const 16)
+ )
+ )
+ )
+ (func (export "deploy"))
+)
+"#;
+
+ #[test]
+ fn tombstone_deposit() {
+ let mut gas_meter = GasMeter::with_limit(50_000, 1);
+ let _ = execute(
+ CODE_TOMBSTONE_DEPOSIT,
+ vec![],
+ MockExt::default(),
+ &mut gas_meter,
+ ).unwrap();
+ }
+
const CODE_RANDOM: &str = r#"
(module
(import "env" "ext_random" (func $ext_random (param i32 i32)))
diff --git a/substrate/frame/contracts/src/wasm/runtime.rs b/substrate/frame/contracts/src/wasm/runtime.rs
index 75751b6d359..07cb8cb524e 100644
--- a/substrate/frame/contracts/src/wasm/runtime.rs
+++ b/substrate/frame/contracts/src/wasm/runtime.rs
@@ -623,6 +623,23 @@ define_env!(Env, <E: Ext>,
Ok(())
},
+ // Stores the tombstone deposit into the scratch buffer.
+ //
+ // The data is encoded as T::Balance. The current contents of the scratch
+ // buffer are overwritten.
+ //
+ // # Note
+ //
+ // The tombstone deposit is on top of the existential deposit. So in order for
+ // a contract to leave a tombstone the balance of the contract must not go
+ // below the sum of existential deposit and the tombstone deposit. The sum
+ // is commonly referred as subsistence threshold in code.
+ ext_tombstone_deposit(ctx) => {
+ ctx.scratch_buf.clear();
+ ctx.ext.tombstone_deposit().encode_to(&mut ctx.scratch_buf);
+ Ok(())
+ },
+
// Decodes the given buffer as a `T::Call` and adds it to the list
// of to-be-dispatched calls.
//
--
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