TryDecodeEntireState check for storage types and pallets

substrate/frame/support/procedural/src/pallet/expand/storage.rs

@@ -849,11 +849,11 @@ pub fn expand_storages(def: &mut Def) -> proc_macro2::TokenStream {
 			impl<#type_impl_gen> #frame_support::traits::TryDecodeEntireStorage
 			for #pallet_ident<#type_use_gen> #completed_where_clause
 			{
-				fn try_decode_entire_state() -> Result<usize, &'static str> {
+				fn try_decode_entire_state() -> Result<usize, #frame_support::traits::TryDecodeEntireStorageError> {
 					// simply delegate impl to a tuple of all storage items we have.
 					//
 					// NOTE: for now, we have to exclude storage items that are feature gated.
-					<( #( #storage_names ),*) as frame_support::traits::TryDecodeEntireStorage>::try_decode_entire_state()
+					<( #( #storage_names ),*) as #frame_support::traits::TryDecodeEntireStorage>::try_decode_entire_state()
 				}
 			}
 		)

substrate/frame/support/src/storage/migration.rs

@@ -408,12 +408,24 @@ impl<AllPallets: crate::traits::TryDecodeEntireStorage> crate::traits::OnRuntime
 	}
 
 	fn post_upgrade(_: Vec<u8>) -> Result<(), sp_runtime::TryRuntimeError> {
-		let decoded = AllPallets::try_decode_entire_state()?;
+		let decoded = match AllPallets::try_decode_entire_state() {
+			Ok(bytes) => bytes,
+			Err(err) => {
+				log::info!(
+					target: crate::LOG_TARGET,
+					"failed to decode the entire state: {}", err
+				);
+				// NOTE: This only supports static strings.
+				return Err("failed to decode a value from the storage".into())
+			}
+		};
+
 		log::info!(
 			target: crate::LOG_TARGET,
 			"decoded the entire state, total size = {} bytes",
 			decoded
 		);
+
 		Ok(())
 	}
 }

substrate/frame/support/src/traits.rs

@@ -126,5 +126,5 @@ pub use tx_pause::{TransactionPause, TransactionPauseError};
 mod try_runtime;
 #[cfg(feature = "try-runtime")]
 pub use try_runtime::{
-	Select as TryStateSelect, TryDecodeEntireStorage, TryState, UpgradeCheckSelect,
+	Select as TryStateSelect, TryDecodeEntireStorageError, TryDecodeEntireStorage, TryState, UpgradeCheckSelect,
 };

substrate/frame/support/src/traits/try_runtime.rs

@@ -63,26 +63,47 @@ impl Default for Select {
 /// decoded bytes if `Ok(_)`.
 pub trait TryDecodeEntireStorage {
 	/// Decode the entire data under the given storage, returning `Ok(bytes_decoded)` if success.
-	fn try_decode_entire_state() -> Result<usize, &'static str>;
+	fn try_decode_entire_state() -> Result<usize, TryDecodeEntireStorageError>;
 }
 
 #[cfg_attr(all(not(feature = "tuples-96"), not(feature = "tuples-128")), impl_for_tuples(64))]
 #[cfg_attr(all(feature = "tuples-96", not(feature = "tuples-128")), impl_for_tuples(96))]
 #[cfg_attr(feature = "tuples-128", impl_for_tuples(128))]
 impl TryDecodeEntireStorage for Tuple {
-	fn try_decode_entire_state() -> Result<usize, &'static str> {
+	fn try_decode_entire_state() -> Result<usize, TryDecodeEntireStorageError> {
 		let mut len = 0usize;
 		for_tuples!( #( len = len.saturating_add(Tuple::try_decode_entire_state()?); )* );
 		Ok(len)
 	}
 }
 
+/// A value could not be decoded.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct TryDecodeEntireStorageError {
+	/// The key of the undecodable value.
+	key: Vec<u8>,
+	/// The raw value.
+	raw: Option<Vec<u8>>,
+	/// The storage info of the key.
+	info: StorageInfo,
+}
+
+impl core::fmt::Display for TryDecodeEntireStorageError {
+	fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+		write!(
+			f,
+			"Failed to decode value at key {:?} with storage info {:?}. Raw value: {:?}",
+			self.key, self.info, self.raw,
+		)
+	}
+}
+
 /// Decode all the values based on the prefix of `info` to `V`.
 ///
 /// Basically, it decodes and sums up all the values who's key start with `info.prefix`. For values,
 /// this would be the value itself. For all sorts of maps, this should be all map items in the
 /// absence of key collision.
-fn decode_storage_info<V: Decode>(info: StorageInfo) -> Result<usize, &'static str> {
+fn decode_storage_info<V: Decode>(info: StorageInfo) -> Result<usize, TryDecodeEntireStorageError> {
 	let mut next_key = info.prefix.clone();
 	let mut decoded = 0;
 
@@ -92,9 +113,9 @@ fn decode_storage_info<V: Decode>(info: StorageInfo) -> Result<usize, &'static s
 			let len = bytes.len();
 			let _ = <V as DecodeAll>::decode_all(&mut bytes.as_ref()).map_err(|_| {
 				log::error!(target: crate::LOG_TARGET, "failed to decoded {:?}", info,);
-				"failed to decode value under existing key"
+				TryDecodeEntireStorageError { key: key.to_vec(), raw: Some(bytes.to_vec()), info: info.clone() }
 			})?;
-			Ok::<usize, &'static str>(len)
+			Ok::<usize, TryDecodeEntireStorageError>(len)
 		},
 	};
 
@@ -120,7 +141,7 @@ where
 	QueryKind: QueryKindTrait<Value, OnEmpty>,
 	OnEmpty: Get<QueryKind::Query> + 'static,
 {
-	fn try_decode_entire_state() -> Result<usize, &'static str> {
+	fn try_decode_entire_state() -> Result<usize, TryDecodeEntireStorageError> {
 		let info = Self::partial_storage_info()
 			.first()
 			.cloned()
@@ -140,7 +161,7 @@ where
 	OnEmpty: Get<QueryKind::Query> + 'static,
 	MaxValues: Get<Option<u32>>,
 {
-	fn try_decode_entire_state() -> Result<usize, &'static str> {
+	fn try_decode_entire_state() -> Result<usize, TryDecodeEntireStorageError> {
 		let info = Self::partial_storage_info()
 			.first()
 			.cloned()
@@ -167,7 +188,7 @@ impl<Prefix, Hasher, Key, Value, QueryKind, OnEmpty, MaxValues> TryDecodeEntireS
 	OnEmpty: Get<QueryKind::Query> + 'static,
 	MaxValues: Get<Option<u32>>,
 {
-	fn try_decode_entire_state() -> Result<usize, &'static str> {
+	fn try_decode_entire_state() -> Result<usize, TryDecodeEntireStorageError> {
 		let (map_info, counter_info) = match &Self::partial_storage_info()[..] {
 			[a, b] => (a.clone(), b.clone()),
 			_ => panic!("Counted map has two storage info items; qed"),
@@ -201,7 +222,7 @@ impl<Prefix, Hasher1, Key1, Hasher2, Key2, Value, QueryKind, OnEmpty, MaxValues>
 	OnEmpty: Get<QueryKind::Query> + 'static,
 	MaxValues: Get<Option<u32>>,
 {
-	fn try_decode_entire_state() -> Result<usize, &'static str> {
+	fn try_decode_entire_state() -> Result<usize, TryDecodeEntireStorageError> {
 		let info = Self::partial_storage_info()
 			.first()
 			.cloned()
@@ -220,7 +241,7 @@ where
 	OnEmpty: Get<QueryKind::Query> + 'static,
 	MaxValues: Get<Option<u32>>,
 {
-	fn try_decode_entire_state() -> Result<usize, &'static str> {
+	fn try_decode_entire_state() -> Result<usize, TryDecodeEntireStorageError> {
 		let info = Self::partial_storage_info()
 			.first()
 			.cloned()
@@ -239,7 +260,7 @@ where
 	OnEmpty: Get<QueryKind::Query> + 'static,
 	MaxValues: Get<Option<u32>>,
 {
-	fn try_decode_entire_state() -> Result<usize, &'static str> {
+	fn try_decode_entire_state() -> Result<usize, TryDecodeEntireStorageError> {
 		let (map_info, counter_info) = match &Self::partial_storage_info()[..] {
 			[a, b] => (a.clone(), b.clone()),
 			_ => panic!("Counted NMap has two storage info items; qed"),