Optimize interpreter::blockchain::{load_contract_code, code_copy to read contract starting from offset

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Changed 
+- [#847](https://github.com/FuelLabs/fuel-vm/pull/847): Remove `contract_read`, and change `load_contract_code`, `code_copy` and `code_root`  to explicitly load the contract code in a buffer. Also check for mismatches between contract size stored and actual size of contract in those functions.
+
 ### Fixed
 - [860](https://github.com/FuelLabs/fuel-vm/pull/860): Fixed missing fuzzing coverage report in CI.
 

fuel-vm/src/interpreter/blockchain.rs

@@ -60,6 +60,7 @@ use fuel_storage::{
 use fuel_tx::{
     consts::BALANCE_ENTRY_SIZE,
     BlobId,
+    Contract,
     ContractIdExt,
     DependentCost,
     Receipt,
@@ -636,8 +637,12 @@ where
             self.gas_cost,
             charge_len,
         )?;
-        let contract = super::contract::contract(self.storage, &contract_id)?;
-        let contract_bytes = contract.as_ref().as_ref();
+
+        let contract_buffer: Vec<u8> = load_contract_code_from_storage(
+            self.storage,
+            contract_len as usize,
+            &contract_id,
+        )?;
 
         let new_sp = ssp.saturating_add(length);
         self.memory.grow_stack(new_sp)?;
@@ -654,7 +659,7 @@ where
         copy_from_slice_zero_fill(
             self.memory,
             owner,
-            contract_bytes,
+            &contract_buffer,
             region_start,
             contract_offset,
             length,
@@ -870,6 +875,28 @@ where
     }
 }
 
+fn load_contract_code_from_storage<S>(
+    storage: &S,
+    contract_len: usize,
+    contract_id: &ContractId,
+) -> Result<Vec<u8>, RuntimeError<<S as InterpreterStorage>::DataError>>
+where
+    S: InterpreterStorage,
+{
+    let mut contract_buffer: Vec<u8> = alloc::vec![0u8; contract_len as usize];
+    storage
+        .read_contract(&contract_id, &mut contract_buffer)
+        .transpose()
+        .ok_or(PanicReason::ContractNotFound)?
+        .map_err(RuntimeError::Storage)?;
+
+    if contract_buffer.len() != contract_len as usize {
+        Err(PanicReason::ContractMismatch)?
+    } else {
+        Ok(contract_buffer)
+    }
+}
+
 struct BurnCtx<'vm, S> {
     storage: &'vm mut S,
     context: &'vm Context,
@@ -994,9 +1021,14 @@ where
         self.memory.write(self.owner, dst_addr, length)?;
         self.input_contracts.check(&contract_id)?;
 
-        let contract = super::contract::contract(self.storage, &contract_id)?;
-        let contract_bytes = contract.as_ref().as_ref();
-        let contract_len = contract_bytes.len();
+        let contract_len = contract_size(self.storage, &contract_id)?;
+
+        let mut contract_buffer = load_contract_code_from_storage(
+            self.storage,
+            contract_len as usize,
+            &contract_id,
+        )?;
+
         let charge_len = core::cmp::max(contract_len as u64, length);
         let profiler = ProfileGas {
             pc: self.pc.as_ref(),
@@ -1016,7 +1048,7 @@ where
         copy_from_slice_zero_fill(
             self.memory,
             self.owner,
-            contract.as_ref().as_ref(),
+            &contract_buffer,
             dst_addr,
             contract_offset,
             length,
@@ -1112,13 +1144,11 @@ impl<'vm, S> CodeRootCtx<'vm, S> {
             self.gas_cost,
             len as u64,
         )?;
-        let root = self
-            .storage
-            .storage_contract(&contract_id)
-            .transpose()
-            .ok_or(PanicReason::ContractNotFound)?
-            .map_err(RuntimeError::Storage)?
-            .root();
+
+        let buf: Vec<u8> =
+            load_contract_code_from_storage(self.storage, len as usize, &contract_id)?;
+
+        let root = Contract::root_from_code(buf);
 
         self.memory.write_bytes(self.owner, a, *root)?;
 

fuel-vm/src/interpreter/contract.rs

@@ -44,7 +44,6 @@ use fuel_asm::{
 };
 use fuel_storage::StorageSize;
 use fuel_tx::{
-    Contract,
     Output,
     Receipt,
 };
@@ -55,8 +54,6 @@ use fuel_types::{
     ContractId,
 };
 
-use alloc::borrow::Cow;
-
 impl<M, S, Tx, Ecal> Interpreter<M, S, Tx, Ecal>
 where
     M: Memory,
@@ -179,19 +176,6 @@ where
     }
 }
 
-pub(crate) fn contract<'s, S>(
-    storage: &'s S,
-    contract: &ContractId,
-) -> IoResult<Cow<'s, Contract>, S::DataError>
-where
-    S: InterpreterStorage,
-{
-    storage
-        .storage_contract(contract)
-        .map_err(RuntimeError::Storage)?
-        .ok_or_else(|| PanicReason::ContractNotFound.into())
-}
-
 struct ContractBalanceCtx<'vm, S> {
     storage: &'vm S,
     memory: &'vm mut MemoryInstance,

fuel-vm/src/storage/interpreter.rs

@@ -145,15 +145,6 @@ pub trait InterpreterStorage:
         Ok(())
     }
 
-    /// Fetch a previously inserted contract code from the chain state for a
-    /// given contract.
-    fn storage_contract(
-        &self,
-        id: &ContractId,
-    ) -> Result<Option<Cow<'_, Contract>>, Self::DataError> {
-        StorageInspect::<ContractsRawCode>::get(self, id)
-    }
-
     /// Fetch the size of a previously inserted contract code from the chain state for a
     /// given contract.
     fn storage_contract_size(

fuel-vm/src/storage/memory.rs

@@ -268,7 +268,8 @@ impl StorageRead<ContractsRawCode> for MemoryStorage {
     ) -> Result<Option<usize>, Self::Error> {
         Ok(self.memory.contracts.get(key).map(|c| {
             let len = buf.len().min(c.as_ref().len());
-            buf.copy_from_slice(&c.as_ref()[..len]);
+            buf[..len].copy_from_slice(&c.as_ref()[..len]);
+            buf[len..].fill(0);
             len
         }))
     }