Update the method for retrieving the device label. (#155)

core/embed/extmod/modtrezorconfig/modtrezorconfig.c

@@ -351,6 +351,41 @@ STATIC mp_obj_t mod_trezorconfig_set_needs_backup(mp_obj_t needs_backup) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_trezorconfig_set_needs_backup_obj,
                                  mod_trezorconfig_set_needs_backup);
 
+/// def get_val_len(app: int, key: int, public: bool = False) -> int:
+///     """
+///     Gets the length of the value of the given key for the given app (or None
+///     if not set). Raises a RuntimeError if decryption or authentication of
+///     the stored value fails.
+///     """
+STATIC mp_obj_t mod_trezorconfig_get_val_len(size_t n_args,
+                                             const mp_obj_t *args) {
+  uint32_t key = trezor_obj_get_uint(args[1]);
+
+  bool is_private = key & (1 << 31);
+
+  secbool (*reader)(uint16_t, void *, uint16_t) =
+      is_private ? se_get_private_region : se_get_public_region;
+
+  // key is position
+  key &= ~(1 << 31);
+
+  uint8_t temp[4] = {0};
+  if (sectrue != reader(key, temp, 3)) {
+    return mp_const_none;
+  }
+  // has flag
+  if (temp[0] != 1) {
+    return mp_const_none;
+  }
+
+  uint16_t len = 0;
+  len = (temp[1] << 8) + temp[2];
+
+  return mp_obj_new_int_from_uint(len);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorconfig_get_val_len_obj, 2,
+                                           3, mod_trezorconfig_get_val_len);
+
 /// def get(app: int, key: int, public: bool = False) -> bytes | None:
 ///     """
 ///     Gets the value of the given key for the given app (or None if not set).
@@ -1118,6 +1153,8 @@ STATIC const mp_rom_map_elem_t mp_module_trezorconfig_globals_table[] = {
      MP_ROM_PTR(&mod_trezorconfig_has_wipe_code_obj)},
     {MP_ROM_QSTR(MP_QSTR_change_wipe_code),
      MP_ROM_PTR(&mod_trezorconfig_change_wipe_code_obj)},
+    {MP_ROM_QSTR(MP_QSTR_get_val_len),
+     MP_ROM_PTR(&mod_trezorconfig_get_val_len_obj)},
     {MP_ROM_QSTR(MP_QSTR_get), MP_ROM_PTR(&mod_trezorconfig_get_obj)},
     {MP_ROM_QSTR(MP_QSTR_set), MP_ROM_PTR(&mod_trezorconfig_set_obj)},
     {MP_ROM_QSTR(MP_QSTR_delete), MP_ROM_PTR(&mod_trezorconfig_delete_obj)},

core/mocks/generated/trezorconfig.pyi

@@ -113,6 +113,15 @@ def set_needs_backup(needs_backup: bool = False) -> bool:
     """
 
 
+# extmod/modtrezorconfig/modtrezorconfig.c
+def get_val_len(app: int, key: int, public: bool = False) -> int:
+    """
+    Gets the length of the value of the given key for the given app (or None if not set).
+    Raises a RuntimeError if decryption or authentication of the stored
+    value fails.
+    """
+
+
 # extmod/modtrezorconfig/modtrezorconfig.c
 def get(app: int, key: int, public: bool = False) -> bytes | None:
     """

core/src/storage/common.py

@@ -25,6 +25,10 @@ def get(app: int, key: int, public: bool = False) -> bytes | None:
     return config.get(app, key, public)
 
 
+def get_val_len(app: int, key: int, public: bool = False) -> int | None:
+    return config.get_val_len(app, key, public)
+
+
 def delete(
     app: int, key: int, public: bool = False, writable_locked: bool = False
 ) -> None:

core/src/storage/device.py

@@ -265,6 +265,7 @@
     DEVICE_ID = struct_public["device_id"][0]
     _VERSION = struct_public["version"][0]
     _LANGUAGE = struct_public["language"][0]
+    _LABEL_DEPRECATED = struct_public["label_deprecated"][0]
     _LABEL = struct_public["label"][0]
     _USE_PASSPHRASE = struct_public["use_passphrase"][0]
     _PASSPHRASE_ALWAYS_ON_DEVICE = struct_public["passphrase_always_on_device"][0]
@@ -723,6 +724,10 @@ def get_label() -> str:
     global _LABEL_VALUE
     if _LABEL_VALUE is None:
         label = common.get(_NAMESPACE, _LABEL, True)  # public
+        if label is None:
+            previous_label_len = common.get_val_len(_NAMESPACE, _LABEL_DEPRECATED, True)
+            if previous_label_len is not None and 0 < previous_label_len < 16:
+                label = common.get(_NAMESPACE, _LABEL_DEPRECATED, True)
         _LABEL_VALUE = label.decode() if label else utils.DEFAULT_LABEL
     return _LABEL_VALUE