fn move_inner()

in key/aziot-keys/src/key_pair.rs [828:923]
82 lines of code
5 McCabe index (conditional complexity)

fn move_inner(
    from: &[crate::implementation::Location],
    to: &[crate::implementation::Location],
) -> Result<(), crate::AZIOT_KEYS_RC> {
    let from = from.first().ok_or_else(|| {
        crate::implementation::err_external("no valid location for source key pair")
    })?;
    let to = to.first().ok_or_else(|| {
        crate::implementation::err_external("no valid location for destination key pair")
    })?;

    match (from, to) {
        (
            crate::implementation::Location::Filesystem(from),
            crate::implementation::Location::Filesystem(to),
        ) => {
            // Rename key in filesystem.
            std::fs::rename(from, to).map_err(crate::implementation::err_external)
        }

        (
            crate::implementation::Location::Filesystem(_),
            crate::implementation::Location::Pkcs11 { .. },
        ) => {
            // Importing a key using this function is not supported.
            Err(crate::implementation::err_invalid_parameter(
                "to",
                "cannot move filesystem key to pkcs11",
            ))
        }

        (
            crate::implementation::Location::Pkcs11 {
                lib_path: lib_path_from,
                uri: from,
            },
            crate::implementation::Location::Pkcs11 {
                lib_path: lib_path_to,
                uri: to,
            },
        ) => {
            let from_label = from.object_label.as_deref().ok_or_else(|| {
                crate::implementation::err_invalid_parameter(
                    "from",
                    "source key missing object label",
                )
            })?;

            let to_label = to.object_label.as_deref().ok_or_else(|| {
                crate::implementation::err_invalid_parameter(
                    "to",
                    "destination key missing object label",
                )
            })?;

            // Delete any existing key pair with the 'to' label.
            let pkcs11_context = pkcs11::Context::load(lib_path_to.clone())
                .map_err(crate::implementation::err_external)?;
            let pkcs11_slot = pkcs11_context
                .find_slot(&to.slot_identifier)
                .map_err(crate::implementation::err_external)?;
            let pkcs11_session = pkcs11_context
                .open_session(pkcs11_slot, to.pin.clone())
                .map_err(crate::implementation::err_external)?;

            pkcs11_session
                .delete_key_pair(to_label)
                .map_err(crate::implementation::err_external)?;

            // Rename key by changing label.
            let pkcs11_context = pkcs11::Context::load(lib_path_from.clone())
                .map_err(crate::implementation::err_external)?;
            let pkcs11_slot = pkcs11_context
                .find_slot(&from.slot_identifier)
                .map_err(crate::implementation::err_external)?;
            let pkcs11_session = pkcs11_context
                .open_session(pkcs11_slot, from.pin.clone())
                .map_err(crate::implementation::err_external)?;

            pkcs11_session
                .rename_key_pair(from_label, to_label)
                .map_err(crate::implementation::err_external)
        }

        (
            crate::implementation::Location::Pkcs11 { .. },
            crate::implementation::Location::Filesystem(_),
        ) => {
            // Cannot export keys to filesystem.
            Err(crate::implementation::err_invalid_parameter(
                "to",
                "cannot move pkcs11 key to filesystem",
            ))
        }
    }
}