Default rent allowance to max_value (#2461)

* Default rent allowance to max_value

* Bump spec version

* Fix exec test

* Address grumbles

* Make test comment less specific

* Default rent_allowance to max_value in exec

* Check default balance on creation

* Check default balance in deploy

* Use hex constant

Co-Authored-By: ascjones <ascjones@gmail.com>

* More specific code const

Co-Authored-By: ascjones <ascjones@gmail.com>

* Update srml/contract/src/tests.rs

Co-Authored-By: ascjones <ascjones@gmail.com>

* Update srml/contract/src/tests.rs

Co-Authored-By: ascjones <ascjones@gmail.com>

* Update srml/contract/src/tests.rs

Co-Authored-By: ascjones <ascjones@gmail.com>

substrate/node/runtime/src/lib.rs

@@ -58,7 +58,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: create_runtime_str!("node"),
 	impl_name: create_runtime_str!("substrate-node"),
 	authoring_version: 10,
-	spec_version: 69,
+	spec_version: 70,
 	impl_version: 70,
 	apis: RUNTIME_API_VERSIONS,
 };

substrate/srml/contract/src/account_db.rs

@@ -25,7 +25,7 @@ use rstd::cell::RefCell;
 use rstd::collections::btree_map::{BTreeMap, Entry};
 use rstd::prelude::*;
 use runtime_io::blake2_256;
-use runtime_primitives::traits::Zero;
+use runtime_primitives::traits::{Bounded, Zero};
 use srml_support::traits::{Currency, Imbalance, SignedImbalance, UpdateBalanceOutcome};
 use srml_support::{storage::child, StorageMap};
 use system;
@@ -123,7 +123,7 @@ impl<T: Trait> AccountDb<T> for DirectAccountDb {
 						storage_size: <Module<T>>::storage_size_offset(),
 						trie_id: <T as Trait>::TrieIdGenerator::trie_id(&address),
 						deduct_block: <system::Module<T>>::block_number(),
-						rent_allowance: <BalanceOf<T>>::zero(),
+						rent_allowance: <BalanceOf<T>>::max_value(),
 					}
 				} else {
 					// No contract exist and no code_hash provided
@@ -213,7 +213,7 @@ impl<'a, T: Trait> OverlayAccountDb<'a, T> {
 		let contract = local.entry(account.clone()).or_insert_with(|| Default::default());
 
 		contract.code_hash = Some(code_hash);
-		contract.rent_allowance = Some(<BalanceOf<T>>::zero());
+		contract.rent_allowance = Some(<BalanceOf<T>>::max_value());
 
 		Ok(())
 	}

substrate/srml/contract/src/exec.rs

@@ -20,7 +20,7 @@ use crate::account_db::{AccountDb, DirectAccountDb, OverlayAccountDb};
 use crate::gas::{GasMeter, Token, approx_gas_for_balance};
 
 use rstd::prelude::*;
-use runtime_primitives::traits::{CheckedAdd, CheckedSub, Zero};
+use runtime_primitives::traits::{Bounded, CheckedAdd, CheckedSub, Zero};
 use srml_support::{StorageMap, traits::{WithdrawReason, Currency}};
 use timestamp;
 
@@ -641,7 +641,7 @@ where
 
 	fn rent_allowance(&self) -> BalanceOf<T> {
 		self.ctx.overlay.get_rent_allowance(&self.ctx.self_account)
-			.unwrap_or(<BalanceOf<T>>::zero()) // Must never be triggered actually
+			.unwrap_or(<BalanceOf<T>>::max_value()) // Must never be triggered actually
 	}
 }
 
@@ -658,7 +658,7 @@ where
 #[cfg(test)]
 mod tests {
 	use super::{
-		ExecFeeToken, ExecutionContext, Ext, Loader, EmptyOutputBuf, TransferFeeKind, TransferFeeToken,
+		BalanceOf, ExecFeeToken, ExecutionContext, Ext, Loader, EmptyOutputBuf, TransferFeeKind, TransferFeeToken,
 		Vm, VmExecResult, InstantiateReceipt, RawEvent,
 	};
 	use crate::account_db::AccountDb;
@@ -1373,7 +1373,7 @@ mod tests {
 		let vm = MockVm::new();
 		let mut loader = MockLoader::empty();
 		let rent_allowance_ch = loader.insert(|ctx| {
-			assert_eq!(ctx.ext.rent_allowance(), 0);
+			assert_eq!(ctx.ext.rent_allowance(), <BalanceOf<Test>>::max_value());
 			ctx.ext.set_rent_allowance(10);
 			assert_eq!(ctx.ext.rent_allowance(), 10);
 			VmExecResult::Ok

substrate/srml/contract/src/tests.rs

@@ -21,7 +21,7 @@
 
 use crate::account_db::{AccountDb, DirectAccountDb, OverlayAccountDb};
 use crate::{
-	ComputeDispatchFee, ContractAddressFor, ContractInfo, ContractInfoOf, GenesisConfig, Module,
+	BalanceOf, ComputeDispatchFee, ContractAddressFor, ContractInfo, ContractInfoOf, GenesisConfig, Module,
 	RawAliveContractInfo, RawEvent, Trait, TrieId, TrieIdFromParentCounter, TrieIdGenerator,
 };
 use assert_matches::assert_matches;
@@ -614,7 +614,6 @@ const CODE_SET_RENT: &str = r#"
 "#;
 const HASH_SET_RENT: [u8; 32] = hex!("a51c2a6f3f68936d4ae9abdb93b28eedcbd0f6f39770e168f9025f0c1e7094ef");
 
-
 /// Input data for each call in set_rent code
 mod call {
 	pub fn set_storage_4_byte() -> Vec<u8> { vec![] }
@@ -900,3 +899,89 @@ fn removals(trigger_call: impl Fn() -> bool) {
 		}
 	);
 }
+
+const CODE_CHECK_DEFAULT_RENT_ALLOWANCE: &str = r#"
+(module
+	(import "env" "ext_rent_allowance" (func $ext_rent_allowance))
+	(import "env" "ext_scratch_size" (func $ext_scratch_size (result i32)))
+	(import "env" "ext_scratch_copy" (func $ext_scratch_copy (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"))
+
+	(func (export "deploy")
+		;; fill the scratch buffer with the rent allowance.
+		(call $ext_rent_allowance)
+
+		;; 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_copy
+			(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 <BalanceOf<T>>::max_value().
+		(call $assert
+			(i64.eq
+				(i64.load
+					(i32.const 8)
+				)
+				(i64.const 0xFFFFFFFFFFFFFFFF)
+			)
+		)
+	)
+)
+"#;
+const HASH_CHECK_DEFAULT_RENT_ALLOWANCE: [u8; 32] = hex!("4f9ec2b94eea522cfff10b77ef4056c631045c00978a457d283950521ecf07b6");
+
+#[test]
+fn default_rent_allowance_on_create() {
+	let wasm = wabt::wat2wasm(CODE_CHECK_DEFAULT_RENT_ALLOWANCE).unwrap();
+
+	with_externalities(
+		&mut ExtBuilder::default().existential_deposit(50).build(),
+		|| {
+			// Create
+			Balances::deposit_creating(&ALICE, 1_000_000);
+			assert_ok!(Contract::put_code(Origin::signed(ALICE), 100_000, wasm));
+			assert_ok!(Contract::create(
+				Origin::signed(ALICE),
+				30_000,
+				100_000,
+				HASH_CHECK_DEFAULT_RENT_ALLOWANCE.into(),
+				vec![],
+			));
+
+			// Check creation
+			let bob_contract = super::ContractInfoOf::<Test>::get(BOB).unwrap().get_alive().unwrap();
+			assert_eq!(bob_contract.rent_allowance, <BalanceOf<Test>>::max_value());
+
+			// Advance blocks
+			System::initialize(&5, &[0u8; 32].into(), &[0u8; 32].into());
+
+			// Trigger rent through call
+			assert_ok!(Contract::call(Origin::signed(ALICE), BOB, 0, 100_000, call::null()));
+
+			// Check contract is still alive
+			let bob_contract = super::ContractInfoOf::<Test>::get(BOB).unwrap().get_alive();
+			assert!(bob_contract.is_some())
+		}
+	);
+}