[BUGFIX] Handle settings on read-only filesystem (#465)

* Handle settings on read-only filesystems

* Cleanup

nam/train/core.py

@@ -982,7 +982,6 @@ def _get_configs(
     batch_size: int,
     fit_mrstft: bool,
 ):
-
     data_config = _get_data_config(
         input_version=input_version,
         input_path=input_path,
@@ -1564,13 +1563,13 @@ def validate_data(
     for split in Split:
         try:
             init_dataset(data_config, split)
-            pytorch_data_split_validation_dict[split.value] = (
-                _PyTorchDataSplitValidation(passed=True, msg=None)
-            )
+            pytorch_data_split_validation_dict[
+                split.value
+            ] = _PyTorchDataSplitValidation(passed=True, msg=None)
         except DataError as e:
-            pytorch_data_split_validation_dict[split.value] = (
-                _PyTorchDataSplitValidation(passed=False, msg=str(e))
-            )
+            pytorch_data_split_validation_dict[
+                split.value
+            ] = _PyTorchDataSplitValidation(passed=False, msg=str(e))
     pytorch_data_validation = _PyTorchDataValidation(
         passed=all(v.passed for v in pytorch_data_split_validation_dict.values()),
         **pytorch_data_split_validation_dict,

nam/train/gui/_resources/settings.py

@@ -42,13 +42,38 @@ def _get_settings() -> dict:
     """
     Make sure that ./settings.json exists; if it does, then read it. If not, empty dict.
     """
-
     if not _SETTINGS_JSON_PATH.exists():
-        _write_settings({})
-    with open(_SETTINGS_JSON_PATH, "r") as fp:
-        return json.load(fp)
+        return dict()
+    else:
+        with open(_SETTINGS_JSON_PATH, "r") as fp:
+            return json.load(fp)
+
+
+class _WriteSettings(object):
+    def __init__(self):
+        self._oserror = False
+
+    def __call__(self, *args, **kwargs):
+        if self._oserror:
+            return
+        # Try-catch for Issue 448
+        try:
+            return _write_settings_unsafe(*args, **kwargs)
+        except OSError as e:
+            if "Read-only filesystem" in str(e):
+                print(
+                    "Failed to write settings--NAM appears to be installed to a "
+                    "read-only filesystem. This is discouraged; consider installing to "
+                    "a location with user-level access."
+                )
+                self._oserror = True
+            else:
+                raise e
+
+
+_write_settings = _WriteSettings()
 
 
-def _write_settings(obj: dict):
+def _write_settings_unsafe(obj: dict):
     with open(_SETTINGS_JSON_PATH, "w") as fp:
         json.dump(obj, fp, indent=4)

tests/test_nam/test_train/test_gui/__init__.py

@@ -0,0 +1,3 @@
+# File: __init__.py
+# Created Date: Tuesday September 17th 2024
+# Author: Steven Atkinson ([email protected])

tests/test_nam/test_train/test_gui/test_resources/test_settings.py

@@ -0,0 +1,44 @@
+# File: test_resources.py
+# Created Date: Tuesday September 17th 2024
+# Author: Steven Atkinson ([email protected])
+
+from contextlib import contextmanager
+from pathlib import Path
+
+import pytest
+
+from nam.train.gui._resources import settings
+
+
+class TestReadOnly(object):
+    """
+    Issue 448
+    """
+
+    @pytest.mark.parametrize("path_key", tuple(pk for pk in settings.PathKey))
+    def test_get_last_path(self, path_key: settings.PathKey):
+        with self._mock_read_only():
+            last_path = settings.get_last_path(path_key)
+        assert last_path is None or isinstance(last_path, Path)
+
+    @pytest.mark.parametrize("path_key", tuple(pk for pk in settings.PathKey))
+    def test_set_last_path(self, path_key: settings.PathKey):
+        path = Path(__file__).parent / Path("dummy.txt")
+        with self._mock_read_only():
+            settings.set_last_path(path_key, path)
+
+    @contextmanager
+    def _mock_read_only(self):
+        def write_settings(*args, **kwargs):
+            raise OSError("Read-only filesystem")
+
+        try:
+            tmp = settings._write_settings_unsafe
+            settings._write_settings_unsafe = write_settings
+            yield
+        finally:
+            settings._write_settings_unsafe = tmp
+
+
+if __name__ == "__main__":
+    pytest.main()