use BoundedVec for the debug buffer

bin/node/runtime/src/lib.rs

@@ -1194,6 +1194,7 @@ impl pallet_contracts::Config for Runtime {
 	type MaxCodeLen = ConstU32<{ 128 * 1024 }>;
 	type MaxStorageKeyLen = ConstU32<128>;
 	type UnsafeUnstableInterface = ConstBool<false>;
+	type MaxDebugBufferLen = ConstU32<{ 2 * 1024 * 1024 }>;
 }
 
 impl pallet_sudo::Config for Runtime {

frame/contracts/src/exec.rs

@@ -18,13 +18,12 @@
 use crate::{
 	gas::GasMeter,
 	storage::{self, Storage, WriteOutcome},
-	BalanceOf, CodeHash, Config, ContractInfo, ContractInfoOf, Determinism, Error, Event, Nonce,
-	Pallet as Contracts, Schedule,
+	BalanceOf, CodeHash, Config, ContractInfo, ContractInfoOf, DebugBufferVec, Determinism, Error,
+	Event, Nonce, Pallet as Contracts, Schedule,
 };
 use frame_support::{
 	crypto::ecdsa::ECDSAExt,
 	dispatch::{DispatchError, DispatchResult, DispatchResultWithPostInfo, Dispatchable},
-	ensure,
 	storage::{with_transaction, TransactionOutcome},
 	traits::{Contains, Currency, ExistenceRequirement, OriginTrait, Randomness, Time},
 	weights::Weight,
@@ -410,7 +409,7 @@ pub struct Stack<'a, T: Config, E> {
 	///
 	/// 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 Vec<u8>>,
+	debug_message: Option<&'a mut DebugBufferVec<T>>,
 	/// The determinism requirement of this call stack.
 	determinism: Determinism,
 	/// No executable is held by the struct but influences its behaviour.
@@ -618,7 +617,7 @@ where
 		schedule: &'a Schedule<T>,
 		value: BalanceOf<T>,
 		input_data: Vec<u8>,
-		debug_message: Option<&'a mut Vec<u8>>,
+		debug_message: Option<&'a mut DebugBufferVec<T>>,
 		determinism: Determinism,
 	) -> Result<ExecReturnValue, ExecError> {
 		let (mut stack, executable) = Self::new(
@@ -653,7 +652,7 @@ where
 		value: BalanceOf<T>,
 		input_data: Vec<u8>,
 		salt: &[u8],
-		debug_message: Option<&'a mut Vec<u8>>,
+		debug_message: Option<&'a mut DebugBufferVec<T>>,
 	) -> Result<(T::AccountId, ExecReturnValue), ExecError> {
 		let (mut stack, executable) = Self::new(
 			FrameArgs::Instantiate {
@@ -682,7 +681,7 @@ where
 		storage_meter: &'a mut storage::meter::Meter<T>,
 		schedule: &'a Schedule<T>,
 		value: BalanceOf<T>,
-		debug_message: Option<&'a mut Vec<u8>>,
+		debug_message: Option<&'a mut DebugBufferVec<T>>,
 		determinism: Determinism,
 	) -> Result<(Self, E), ExecError> {
 		let (first_frame, executable, nonce) = Self::new_frame(
@@ -1332,12 +1331,7 @@ where
 	fn append_debug_buffer(&mut self, msg: &str) -> Result<bool, ()> {
 		if let Some(buffer) = &mut self.debug_message {
 			if !msg.is_empty() {
-				ensure!(
-					buffer.len().checked_add(msg.len()).ok_or(())? <=
-						self.schedule.limits.debug_buffer_len as usize,
-					()
-				);
-				buffer.extend(msg.as_bytes());
+				buffer.try_append(&mut msg.as_bytes().to_vec())?;
 			}
 			Ok(true)
 		} else {
@@ -2518,7 +2512,7 @@ mod tests {
 			exec_success()
 		});
 
-		let mut debug_buffer = Vec::new();
+		let mut debug_buffer = DebugBufferVec::<Test>::try_from(Vec::new()).unwrap();
 
 		ExtBuilder::default().build().execute_with(|| {
 			let min_balance = <Test as Config>::Currency::minimum_balance();
@@ -2541,7 +2535,7 @@ mod tests {
 			.unwrap();
 		});
 
-		assert_eq!(&String::from_utf8(debug_buffer).unwrap(), "This is a testMore text");
+		assert_eq!(&String::from_utf8(debug_buffer.to_vec()).unwrap(), "This is a testMore text");
 	}
 
 	#[test]
@@ -2556,7 +2550,7 @@ mod tests {
 			exec_trapped()
 		});
 
-		let mut debug_buffer = Vec::new();
+		let mut debug_buffer = DebugBufferVec::<Test>::try_from(Vec::new()).unwrap();
 
 		ExtBuilder::default().build().execute_with(|| {
 			let min_balance = <Test as Config>::Currency::minimum_balance();
@@ -2579,7 +2573,7 @@ mod tests {
 			assert!(result.is_err());
 		});
 
-		assert_eq!(&String::from_utf8(debug_buffer).unwrap(), "This is a testMore text");
+		assert_eq!(&String::from_utf8(debug_buffer.to_vec()).unwrap(), "This is a testMore text");
 	}
 
 	#[test]
@@ -2593,7 +2587,8 @@ mod tests {
 		});
 
 		// Pre-fill the buffer up to its limit
-		let mut debug_buffer = vec![0u8; schedule.limits.debug_buffer_len as usize];
+		let mut debug_buffer =
+			DebugBufferVec::<Test>::try_from(vec![0u8; DebugBufferVec::<Test>::bound()]).unwrap();
 
 		ExtBuilder::default().build().execute_with(|| {
 			let min_balance = <Test as Config>::Currency::minimum_balance();

frame/contracts/src/lib.rs

@@ -142,6 +142,7 @@ type BalanceOf<T> =
 type CodeVec<T> = BoundedVec<u8, <T as Config>::MaxCodeLen>;
 type RelaxedCodeVec<T> = WeakBoundedVec<u8, <T as Config>::MaxCodeLen>;
 type AccountIdLookupOf<T> = <<T as frame_system::Config>::Lookup as StaticLookup>::Source;
+type DebugBufferVec<T> = BoundedVec<u8, <T as Config>::MaxDebugBufferLen>;
 
 /// Used as a sentinel value when reading and writing contract memory.
 ///
@@ -344,6 +345,10 @@ pub mod pallet {
 		/// Do **not** set to `true` on productions chains.
 		#[pallet::constant]
 		type UnsafeUnstableInterface: Get<bool>;
+
+		/// The maximum length of the debug buffer in bytes.
+		#[pallet::constant]
+		type MaxDebugBufferLen: Get<u32>;
 	}
 
 	#[pallet::hooks]
@@ -952,7 +957,7 @@ where
 		debug: bool,
 		determinism: Determinism,
 	) -> ContractExecResult<BalanceOf<T>> {
-		let mut debug_message = if debug { Some(Vec::new()) } else { None };
+		let mut debug_message = if debug { Some(DebugBufferVec::<T>::default()) } else { None };
 		let output = Self::internal_call(
 			origin,
 			dest,
@@ -968,7 +973,7 @@ where
 			gas_consumed: output.gas_meter.gas_consumed(),
 			gas_required: output.gas_meter.gas_required(),
 			storage_deposit: output.storage_deposit,
-			debug_message: debug_message.unwrap_or_default(),
+			debug_message: debug_message.unwrap_or_default().to_vec(),
 		}
 	}
 
@@ -994,7 +999,7 @@ where
 		salt: Vec<u8>,
 		debug: bool,
 	) -> ContractInstantiateResult<T::AccountId, BalanceOf<T>> {
-		let mut debug_message = if debug { Some(Vec::new()) } else { None };
+		let mut debug_message = if debug { Some(DebugBufferVec::<T>::default()) } else { None };
 		let output = Self::internal_instantiate(
 			origin,
 			value,
@@ -1013,7 +1018,7 @@ where
 			gas_consumed: output.gas_meter.gas_consumed(),
 			gas_required: output.gas_meter.gas_required(),
 			storage_deposit: output.storage_deposit,
-			debug_message: debug_message.unwrap_or_default(),
+			debug_message: debug_message.unwrap_or_default().to_vec(),
 		}
 	}
 
@@ -1104,7 +1109,7 @@ where
 		gas_limit: Weight,
 		storage_deposit_limit: Option<BalanceOf<T>>,
 		data: Vec<u8>,
-		debug_message: Option<&mut Vec<u8>>,
+		debug_message: Option<&mut DebugBufferVec<T>>,
 		determinism: Determinism,
 	) -> InternalCallOutput<T> {
 		let mut gas_meter = GasMeter::new(gas_limit);
@@ -1147,7 +1152,7 @@ where
 		code: Code<CodeHash<T>>,
 		data: Vec<u8>,
 		salt: Vec<u8>,
-		mut debug_message: Option<&mut Vec<u8>>,
+		mut debug_message: Option<&mut DebugBufferVec<T>>,
 	) -> InternalInstantiateOutput<T> {
 		let mut storage_deposit = Default::default();
 		let mut gas_meter = GasMeter::new(gas_limit);
@@ -1163,7 +1168,9 @@ where
 						TryInstantiate::Skip,
 					)
 					.map_err(|(err, msg)| {
-						debug_message.as_mut().map(|buffer| buffer.extend(msg.as_bytes()));
+						debug_message
+							.as_mut()
+							.map(|buffer| buffer.try_append(&mut msg.as_bytes().to_vec()));
 						err
 					})?;
 					// The open deposit will be charged during execution when the

frame/contracts/src/tests.rs

@@ -415,6 +415,7 @@ impl Config for Test {
 	type MaxCodeLen = ConstU32<{ 128 * 1024 }>;
 	type MaxStorageKeyLen = ConstU32<128>;
 	type UnsafeUnstableInterface = UnstableInterface;
+	type MaxDebugBufferLen = ConstU32<{ 2 * 1024 * 1024 }>;
 }
 
 pub const ALICE: AccountId32 = AccountId32::new([1u8; 32]);