Fix last iteration in sequential opcode (#2479)

Fixes #2022

Previously the read and write of the last key of the contract state was
creating error because of multiple bad checks of limits. Also the key
was increase in all case at the end of the loop causing the `increase()`
to fail on overflow even if there is values to be inserted left.

## Checklist
- [x] Breaking changes are clearly marked as such in the PR description
and changelog
- [x] New behavior is reflected in tests
- [x] [The specification](https://github.com/FuelLabs/fuel-specs/)
matches the implemented behavior (link update PR if changes are needed)

### Before requesting review
- [x] I have reviewed the code myself
- [x] I have created follow-up issues caused by this PR and linked them
here

---------

Co-authored-by: Green Baneling <[email protected]>

CHANGELOG.md

@@ -36,6 +36,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - [2369](https://github.com/FuelLabs/fuel-core/pull/2369): The `transaction_insertion_time_in_thread_pool_milliseconds` metric is properly collected.
 - [2413](https://github.com/FuelLabs/fuel-core/issues/2413): block production immediately errors if unable to lock the mutex.
 - [2389](https://github.com/FuelLabs/fuel-core/pull/2389): Fix construction of reverse iterator in RocksDB.
+- [2479](https://github.com/FuelLabs/fuel-core/pull/2479): Fix an error on the last iteration of the read and write sequential opcodes on contract storage.
 - [2478](https://github.com/FuelLabs/fuel-core/pull/2478): Fix proof created by `message_receipts_proof` function by ignoring the receipts from failed transactions to match `message_outbox_root`.
 - [2485](https://github.com/FuelLabs/fuel-core/pull/2485): Hardcode the timestamp of the genesis block and version of `tai64` to avoid breaking changes for us.
 

crates/storage/src/vm_storage.rs

@@ -344,11 +344,13 @@ where
         let mut state_key = Bytes32::zeroed();
 
         let mut results = Vec::new();
-        for _ in 0..range {
+        for i in 0..range {
+            if i != 0 {
+                key.increase()?;
+            }
             key.to_big_endian(state_key.as_mut());
             let multikey = ContractsStateKey::new(contract_id, &state_key);
             results.push(self.database.storage::<ContractsState>().get(&multikey)?);
-            key.increase()?;
         }
         Ok(results)
     }
@@ -367,12 +369,15 @@ where
 
         // verify key is in range
         current_key
-            .checked_add(U256::from(values.len()))
+            .checked_add(U256::from(values.len().saturating_sub(1)))
             .ok_or_else(|| anyhow!("range op exceeded available keyspace"))?;
 
         let mut key_bytes = Bytes32::zeroed();
         let mut found_unset = 0u32;
-        for value in values {
+        for (idx, value) in values.iter().enumerate() {
+            if idx != 0 {
+                current_key.increase()?;
+            }
             current_key.to_big_endian(key_bytes.as_mut());
 
             let option = self
@@ -385,8 +390,6 @@ where
                     .checked_add(1)
                     .expect("We've checked it above via `values.len()`");
             }
-
-            current_key.increase()?;
         }
 
         Ok(found_unset as usize)
@@ -403,7 +406,10 @@ where
         let mut current_key = U256::from_big_endian(start_key.as_ref());
 
         let mut key_bytes = Bytes32::zeroed();
-        for _ in 0..range {
+        for i in 0..range {
+            if i != 0 {
+                current_key.increase()?;
+            }
             current_key.to_big_endian(key_bytes.as_mut());
 
             let option = self
@@ -412,8 +418,6 @@ where
                 .take(&(contract_id, &key_bytes).into())?;
 
             found_unset |= option.is_none();
-
-            current_key.increase()?;
         }
 
         if found_unset {

tests/tests/vm_storage.rs

@@ -86,6 +86,11 @@ mod tests {
     => Err(())
     ; "read fails on partially initialized range if keyspace exceeded"
     )]
+    #[test_case(
+    &[(*u256_to_bytes32(U256::MAX), vec![0; 32])], *u256_to_bytes32(U256::MAX), 1
+    => Ok(vec![Some(vec![0; 32])])
+    ; "read success when reading last key"
+    )]
     fn read_sequential_range(
         prefilled_slots: &[([u8; 32], Vec<u8>)],
         start_key: [u8; 32],
@@ -161,6 +166,11 @@ mod tests {
     => Err(())
     ; "insert fails if start_key + range > u256::MAX"
     )]
+    #[test_case(
+    &[(*u256_to_bytes32(U256::MAX), vec![0; 32])], *u256_to_bytes32(U256::MAX), &[vec![1; 32]]
+    => Ok(true)
+    ; "try to modify only the last value of storage"
+    )]
     fn insert_range(
         prefilled_slots: &[([u8; 32], Vec<u8>)],
         start_key: [u8; 32],
@@ -255,6 +265,11 @@ mod tests {
     => (vec![], false)
     ; "remove multiple slots over partially uninitialized middle range"
     )]
+    #[test_case(
+    &[(*u256_to_bytes32(U256::MAX), vec![0; 32])], *u256_to_bytes32(U256::MAX), 1
+    => (vec![], true)
+    ; "try to modify only the last value of storage"
+    )]
     fn remove_range(
         prefilled_slots: &[([u8; 32], Vec<u8>)],
         start_key: [u8; 32],