rusk: Support a revert to a specified commit id

rusk/src/lib/error.rs

@@ -49,6 +49,8 @@ pub enum Error {
     InconsistentState(VerificationOutput),
     /// Other
     Other(Box<dyn std::error::Error>),
+    /// Commit not found amongst existing commits
+    CommitNotFound([u8; 32]),
 }
 
 impl std::error::Error for Error {}
@@ -140,6 +142,9 @@ impl fmt::Display for Error {
                     "Inconsistent state verification data {verification_output}",
                 )
             }
+            Error::CommitNotFound(commit_id) => {
+                write!(f, "Commit not found, id = {}", hex::encode(commit_id),)
+            }
         }
     }
 }

rusk/src/lib/lib.rs

@@ -334,9 +334,15 @@ impl Rusk {
         Ok(())
     }
 
-    pub fn revert(&self) -> Result<[u8; 32]> {
+    pub fn revert(&self, state_hash: [u8; 32]) -> Result<[u8; 32]> {
         let mut inner = self.inner.lock();
-        inner.current_commit = inner.base_commit;
+
+        let mut commits = &inner.vm.commits();
+        if !commits.contains(&state_hash) {
+            return Err(Error::CommitNotFound(state_hash));
+        }
+
+        inner.current_commit = state_hash;
         Ok(inner.current_commit)
     }
 

rusk/src/lib/vm.rs

@@ -149,9 +149,13 @@ impl VMExecution for Rusk {
         Ok(self.state_root())
     }
 
-    fn revert(&self) -> anyhow::Result<[u8; 32]> {
+    fn get_base_state_root(&self) -> anyhow::Result<[u8; 32]> {
+        Ok(self.base_root())
+    }
+
+    fn revert(&self, state_hash: [u8; 32]) -> anyhow::Result<[u8; 32]> {
         let state_hash = self
-            .revert()
+            .revert(state_hash)
             .map_err(|inner| anyhow::anyhow!("Cannot revert: {inner}"))?;
 
         Ok(state_hash)