fix(udev): restrict mode switching to intended devices and events

Take the aic.rules portion of #129: restrict 1111:1111 switching to
88M80 USB devices, target the event's bus/device address, and eject only
whole disks on add. Add selection fixtures and document the product
restriction. Keep installer paths and existing firmware handling unchanged.

Co-authored-by: rtk94 <richardtknepp@gmail.com>

tests/installer/test_udev.py

@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+"""Check device/event selection using fixtures; does not switch real devices.
+
+This models the basic equality/glob predicates used by aic.rules. Run
+udevadm verify separately to validate syntax with the real udev parser.
+"""
+
+from fnmatch import fnmatchcase
+from pathlib import Path
+import re
+import unittest
+
+
+RULES = (Path(__file__).resolve().parents[2] / "aic.rules").read_text().splitlines()
+
+
+def matching_rules(device):
+    result = []
+    for rule in RULES:
+        if not rule.strip() or rule.lstrip().startswith("#"):
+            continue
+        predicates = re.findall(r'([A-Z]+(?:\{[^}]+\})?)=="([^"]*)"', rule)
+        if predicates and all(fnmatchcase(device.get(key, ""), value) for key, value in predicates):
+            result.append(rule)
+    return result
+
+
+class UdevTests(unittest.TestCase):
+    def pandora(self, **changes):
+        device = {"ACTION": "add", "SUBSYSTEM": "usb", "ENV{DEVTYPE}": "usb_device",
+                  "ATTR{idVendor}": "1111", "ATTR{idProduct}": "1111", "ATTR{product}": "88M80"}
+        device.update(changes)
+        return device
+
+    def test_88m80_uses_event_bus_and_device_numbers(self):
+        for product in ("88M80", "88M80 USB WiFi"):
+            with self.subTest(product=product):
+                matches = matching_rules(self.pandora(**{"ATTR{product}": product}))
+                self.assertEqual(len(matches), 1)
+                # Both possible usb_modeswitch executable locations target this event's device.
+                self.assertEqual(matches[0].count("-b $attr{busnum} -g $attr{devnum}"), 2)
+
+    def test_generic_1111_flash_disk_is_not_switched(self):
+        for product in ("FLASH UDISK 2.30", "USB DISK", ""):
+            with self.subTest(product=product):
+                self.assertEqual(matching_rules(self.pandora(**{"ATTR{product}": product})), [])
+
+    def test_wrong_ids_interfaces_and_non_add_events_are_not_switched(self):
+        for changes in ({"ACTION": "change"}, {"ACTION": "remove"},
+                        {"ENV{DEVTYPE}": "usb_interface"}, {"ATTR{idVendor}": "2222"},
+                        {"ATTR{idProduct}": "8d80"}):
+            with self.subTest(changes=changes):
+                self.assertEqual(matching_rules(self.pandora(**changes)), [])
+
+    def test_eject_only_on_add_of_a_whole_supported_disk(self):
+        for product in ("5721", "5722", "5723", "5724", "5725", "5726", "5727", "572a", "572c", "572f"):
+            disk = {"ACTION": "add", "SUBSYSTEM": "block", "ENV{DEVTYPE}": "disk", "KERNEL": "sdb",
+                    "ATTRS{idVendor}": "a69c", "ATTRS{idProduct}": product}
+            with self.subTest(product=product):
+                matches = matching_rules(disk)
+                self.assertEqual(len(matches), 1)
+                self.assertIn('/usr/bin/eject /dev/%k', matches[0])
+                for changes in ({"ACTION": "change"}, {"ACTION": "remove"},
+                                {"ENV{DEVTYPE}": "partition", "KERNEL": "sdb1"}):
+                    self.assertEqual(matching_rules(dict(disk, **changes)), [])
+
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)