Function prepare_sandbox_overlay_image

crates/openshell-driver-vm/src/driver.rs:4601–4650

(
    template_path: &Path,
    overlay_disk: &Path,
    tls_materials: Option<&GuestTlsMaterials>,
    sandbox_token: Option<&str>,
    preparation: OverlayPreparation,
    expected_size_bytes: u64,

}

fn prepare_sandbox_overlay_image(
    template_path: &Path,
    overlay_disk: &Path,
    tls_materials: Option<&GuestTlsMaterials>,
    sandbox_token: Option<&str>,
    preparation: OverlayPreparation,
    expected_size_bytes: u64,
) -> Result<(), String> {
    if preparation == OverlayPreparation::PreserveExisting {
        match fs::metadata(overlay_disk) {
            Ok(metadata) if metadata.is_file() && metadata.len() == expected_size_bytes => {
                if let Some(tls) = tls_materials {
                    inject_guest_tls_materials(overlay_disk, tls)?;
                }
                if let Some(token) = sandbox_token {
                    inject_guest_sandbox_token(overlay_disk, token)?;
                }
                return Ok(());
            }
            Ok(metadata) if metadata.is_file() => {
                return Err(format!(
                    "existing overlay disk '{}' has size {}, expected {}",
                    overlay_disk.display(),
                    metadata.len(),
                    expected_size_bytes
                ));
            }
            Ok(_) => {
                return Err(format!(
                    "existing overlay path '{}' is not a file",
                    overlay_disk.display()
                ));
            }
            Err(err) if err.kind() == std::io::ErrorKind::NotFound => {}
            Err(err) => {
                return Err(format!(
                    "stat overlay disk {}: {err}",
                    overlay_disk.display()
                ));
            }
        }
    }

    create_sandbox_overlay_image_from_template(
        template_path,
        overlay_disk,
        tls_materials,
        sandbox_token,
    )
}

fn inject_guest_tls_materials(
    overlay_disk: &Path,