fix: limit export filename length to 255 bytes

fix #15

evernote_backup/note_exporter_util.py

@@ -91,25 +91,44 @@ def _get_non_existant_name(file_name: str, target_dir: Path) -> str:
 def _trim_name(file_name: str, max_len: int = MAX_FILE_NAME_LEN) -> str:
     """Trim file name to 255 characters while maintaining extension
     255 characters is max file name length on linux and macOS
-    Windows has a path limit of 260 characters which includes
-    the entire path (drive letter, path, and file name)
-    This does not trim the path length, just the file name
+    Windows has a filename limit of 260 bytes
+
+    Assuming character is one byte
+    Trimming only stem, extensions stays untouched
 
     max_len: if provided, trims to this length otherwise MAX_FILE_NAME_LEN
 
     Raises: ValueError if the file name is too long and cannot be trimmed
     """
-    if len(file_name) <= max_len:
+    if len(file_name.encode("utf-8")) <= max_len:
         return file_name
 
     orig = Path(file_name)
 
-    drop_chars = len(file_name) - max_len
-    trimmed_name = orig.stem[:-drop_chars]
+    if orig.suffix:
+        max_len_name = max_len - len(orig.suffix.encode("utf-8"))
+    else:
+        max_len_name = max_len
+
+    trimmed_name = _trim_string(orig.stem, max_len_name)
+
+    result_name = f"{trimmed_name}{orig.suffix}"
+
+    if len(result_name.encode("utf-8")) > max_len:
+        raise ValueError(
+            f"File name is too long but cannot be safely trimmed: {file_name}"
+        )
+
+    return result_name
+
+
+def _trim_string(string: str, max_len: int) -> str:
+    if max_len <= 0:
+        return ""
+
+    chars = list(string)
 
-    if not orig.suffix:
-        return trimmed_name
-    if len(orig.stem) > drop_chars:
-        return f"{trimmed_name}{orig.suffix}"
+    while sum(len(c.encode("utf-8")) for c in chars) > max_len:
+        chars.pop(-1)
 
-    raise ValueError(f"File name is too long but cannot be safely trimmed: {file_name}")
+    return "".join(chars)

tests/test_note_exporter_util.py

@@ -111,7 +111,7 @@ def test_safe_path_long_file_name(tmp_path):
     safe_path = SafePath(test_dir)
     result_file_path = safe_path.get_file("test1", long_file_name)
 
-    expected_file.touch()
+    result_file_path.touch()
 
     assert expected_file.is_file()
     assert result_file_path == expected_file
@@ -136,7 +136,7 @@ def test_safe_path_long_file_name_existing(tmp_path):
     safe_path = SafePath(test_dir)
     result_file_path = safe_path.get_file(long_file_name)
 
-    expected_file.touch()
+    result_file_path.touch()
 
     assert expected_file.is_file()
     assert result_file_path == expected_file
@@ -155,7 +155,26 @@ def test_safe_path_long_file_name_no_ext(tmp_path):
     safe_path = SafePath(test_dir)
     result_file_path = safe_path.get_file("test1", long_file_name)
 
-    expected_file.touch()
+    result_file_path.touch()
+
+    assert expected_file.is_file()
+    assert result_file_path == expected_file
+
+
+def test_safe_path_long_file_name_no_ext_unicode(tmp_path):
+    """Test that SafePath trims a long file name with no extension"""
+    test_dir = tmp_path / "test"
+
+    slightly_longer_than_supported = MAX_FILE_NAME_LEN * 2
+
+    long_file_name = "😁" * slightly_longer_than_supported
+    expected_file_name = "😁" * (MAX_FILE_NAME_LEN // len("😁".encode("utf-8")))
+    expected_file = tmp_path / "test" / "test1" / expected_file_name
+
+    safe_path = SafePath(test_dir)
+    result_file_path = safe_path.get_file("test1", long_file_name)
+
+    result_file_path.touch()
 
     assert expected_file.is_file()
     assert result_file_path == expected_file

tests/test_op_export.py

@@ -320,6 +320,37 @@ def test_export_single_notes_over_existing_overwrite(
     assert book2_existing_path.stat().st_size > 0
 
 
+@pytest.mark.usefixtures("fake_init_db")
+def test_export_single_notes_super_long_name(cli_invoker, fake_storage, tmp_path):
+    test_out_path = tmp_path / "test_out"
+
+    test_long_title = "😁" * 300
+    expected_note_name = f"{'😁' * 62}.enex"
+
+    test_notebooks = [Notebook(guid="nbid1", name="name1", stack=None)]
+
+    test_notes = [
+        Note(
+            guid="id1",
+            title=test_long_title,
+            content="test",
+            notebookGuid="nbid1",
+            active=True,
+        )
+    ]
+
+    fake_storage.notebooks.add_notebooks(test_notebooks)
+
+    for note in test_notes:
+        fake_storage.notes.add_note(note)
+
+    cli_invoker("export", "--database", "fake_db", "--single-notes", str(test_out_path))
+
+    note_path = test_out_path / "name1" / expected_note_name
+
+    assert note_path.is_file()
+
+
 @pytest.mark.usefixtures("fake_init_db")
 def test_export_no_trash(cli_invoker, fake_storage, tmp_path):
     test_out_path = tmp_path / "test_out"