fixup! Snapshot persistence to disk

Author: ludfjig

src/hyperlight_host/src/sandbox/snapshot.rs

@@ -1563,6 +1563,44 @@ mod snapshot_file_tests {
         );
     }
 
+    #[test]
+    fn hypervisor_mismatch_rejected() {
+        let snapshot = create_snapshot_from_binary();
+
+        let dir = tempfile::tempdir().unwrap();
+        let snap_path = dir.path().join("wrong_hv.hls");
+        snapshot.to_file(&snap_path).unwrap();
+
+        // Overwrite the hypervisor tag (offset 168, 8 bytes) with a
+        // valid but wrong hypervisor tag.
+        use super::HypervisorTag;
+        let current = HypervisorTag::current().unwrap();
+        let wrong_tag = match current {
+            HypervisorTag::Whp => HypervisorTag::Kvm,
+            _ => HypervisorTag::Whp,
+        };
+        {
+            use std::io::{Seek, SeekFrom, Write};
+            let mut file = std::fs::OpenOptions::new()
+                .write(true)
+                .open(&snap_path)
+                .unwrap();
+            file.seek(SeekFrom::Start(168)).unwrap();
+            file.write_all(&(wrong_tag as u64).to_le_bytes()).unwrap();
+        }
+
+        let result = Snapshot::from_file(&snap_path);
+        let err_msg = match result {
+            Err(e) => format!("{}", e),
+            Ok(_) => panic!("expected load to fail with hypervisor mismatch"),
+        };
+        assert!(
+            err_msg.contains("hypervisor mismatch"),
+            "expected hypervisor mismatch error, got: {}",
+            err_msg
+        );
+    }
+
     #[test]
     fn restore_from_loaded_snapshot() {
         let mut sbox = create_test_sandbox();