uvk5: Add a restricted version for unsupported firmwares

Since this is such a problem (new firmwares popping up everywhere),
add a fallback version-agnostic implementation of the base class
that is fully read-only (and won't upload). This will mean that
anyone with an unsupported firmware will be able to download the image
for inspection and make it easier for us to determine if we should
just whitelist the version.

chirp/drivers/uvk5.py

@@ -2075,11 +2075,45 @@ def detect_from_serial(cls, pipe):
         for rclass in cls.detected_models():
             if rclass.k5_approve_firmware(firmware):
                 return rclass
-        raise errors.RadioError('Firmware %r not supported' % firmware)
+
+        return UVK5RestrictedRadio
 
 
 @directory.register
 class RA79Radio(UVK5Radio):
     """Retevis RA79"""
     VENDOR = "Retevis"
     MODEL = "RA79"
+
+
+@directory.register
+@directory.detected_by(UVK5Radio)
+class UVK5RestrictedRadio(UVK5RadioBase):
+    VARIANT = 'unsupported'
+
+    @classmethod
+    def k5_approve_firmware(cls, firmware):
+        return False
+
+    def process_mmap(self):
+        firmware = self.metadata.get('uvk5_firmware', '<unknown>')
+        LOG.warning('Firmware %s is not supported by CHIRP. '
+                    'Image data will be read-only.', firmware)
+        self._memobj = bitwise.parse(MEM_FORMAT, self._mmap)
+
+    def sync_out(self):
+        raise errors.RadioError(
+            _('Upload is disabled due to unsupported firmware version'))
+
+    def get_memory(self, n):
+        mem = super().get_memory(n)
+        mem.immutable = dir(mem)
+        return mem
+
+    def set_memory(self, m):
+        raise errors.InvalidValueError(
+            _('Memories are read-only due to unsupported firmware version'))
+
+    def set_settings(self, settings):
+        raise errors.InvalidValueError(
+            _('Settings are read-only due to unsupported firmware version'))