Some printing

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

Author: ludfjig

src/hyperlight_host/src/sandbox/initialized_multi_use.rs

@@ -349,6 +349,34 @@ impl MultiUseSandbox {
         // The restored snapshot is now our most current snapshot
         self.snapshot = Some(snapshot.clone());
 
+        // DEBUG: Verify snapshot memory was correctly written to shared_mem.
+        // Compare the first 4KB of the snapshot with what's in shared_mem
+        // to detect if restore_from_snapshot failed silently.
+        {
+            let snap_bytes = snapshot.memory();
+            let check_len = 4096.min(snap_bytes.len());
+            let mut host_bytes = vec![0u8; check_len];
+            if self
+                .mem_mgr
+                .shared_mem
+                .copy_to_slice(&mut host_bytes, 0)
+                .is_ok()
+            {
+                if host_bytes[..check_len] != snap_bytes[..check_len] {
+                    let first_diff = host_bytes
+                        .iter()
+                        .zip(snap_bytes.iter())
+                        .position(|(a, b)| a != b);
+                    println!(
+                        "SNAPSHOT MISMATCH: first diff at byte {}, host={:#x} snap={:#x}",
+                        first_diff.unwrap_or(0),
+                        host_bytes[first_diff.unwrap_or(0)],
+                        snap_bytes[first_diff.unwrap_or(0)],
+                    );
+                }
+            }
+        }
+
         // Clear poison state when successfully restoring from snapshot.
         //
         // # Safety:
@@ -714,6 +742,27 @@ impl MultiUseSandbox {
 
             self.mem_mgr.write_guest_function_call(buffer)?;
 
+            // DEBUG: Check if snapshot memory is still intact before dispatch.
+            // If this fires, something corrupted host memory between restore and dispatch.
+            {
+                let check_len = 4096.min(self.mem_mgr.shared_mem.mem_size());
+                let mut host_bytes = vec![0u8; check_len];
+                if self
+                    .mem_mgr
+                    .shared_mem
+                    .copy_to_slice(&mut host_bytes, 0)
+                    .is_ok()
+                {
+                    // Check if the first page is all zeros (which would indicate corruption)
+                    let all_zero = host_bytes.iter().all(|&b| b == 0);
+                    if all_zero {
+                        println!(
+                            "PRE-DISPATCH: first 4KB of shared_mem is ALL ZEROS — snapshot data lost"
+                        );
+                    }
+                }
+            }
+
             let dispatch_res = self.vm.dispatch_call_from_host(
                 &mut self.mem_mgr,
                 &self.host_funcs,