Merge pull request #1006: stop the installer space check at an unavailable drive root (Luxury213)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

installer/steps.py

@@ -168,7 +168,8 @@ def run_tool(ctx, step, script, args, parse=None, cwd=None):
 def free_bytes(path):
     """Free bytes on the disk of path (its nearest existing parent) and that parent's device."""
     p = Path(path)
-    while not p.exists():
+    # An unavailable drive or share has no existing ancestor: let disk_usage report its OS error at the root.
+    while not p.exists() and p.parent != p:
         p = p.parent
     return shutil.disk_usage(p).free, os.stat(p).st_dev
 

tests/installer_test.py

@@ -489,6 +489,29 @@ class CleanupTest(unittest.TestCase):
         self.assertEqual(self.run_cleanup(), 'cleanup.romfs_unreadable')
 
 
+class FreeSpaceTest(unittest.TestCase):
+    def test_missing_folders_use_the_nearest_existing_parent(self):
+        with tempfile.TemporaryDirectory() as d:
+            parent = Path(d)
+            path = parent / 'missing' / 'install'
+            with mock.patch.object(steps.shutil, 'disk_usage', return_value=SimpleNamespace(free=1234)) as usage:
+                self.assertEqual(steps.free_bytes(path), (1234, parent.stat().st_dev))
+            usage.assert_called_once_with(parent)
+            self.assertFalse(path.parent.exists())
+
+    def test_missing_root_reports_the_filesystem_error(self):
+        path = Path(ROOT.anchor) / 'missing' / 'install'
+        root = Path(path.anchor)
+        error = FileNotFoundError(2, 'No such file or directory', str(root))
+        # Bound the failed existence checks so the old parent walk cannot hang the test suite.
+        with mock.patch.object(Path, 'exists', side_effect=[False] * (len(path.parents) + 1)):
+            with mock.patch.object(steps.shutil, 'disk_usage', side_effect=error) as usage:
+                with self.assertRaises(FileNotFoundError) as raised:
+                    steps.free_bytes(path)
+        self.assertIs(raised.exception, error)
+        usage.assert_called_once_with(root)
+
+
 class BaseGameCheckTest(unittest.TestCase):
     """Issue #261: an update NSP chosen as the base game was reported as "not Tears of the Kingdom"."""
     BASE, UPDATE = '0100F2C0115B6000', '0100F2C0115B6800'