Preserve journal file permissions.

Fixes jbms#231

beancount_import/journal_editor.py

@@ -235,11 +235,22 @@ def get_partially_booked_entries(pre_booking_entries: Entries,
 
 
 class _AtomicWriter(atomicwrites.AtomicWriter):
-    """Wrapper that calls `os.stat` after close but before the rename."""
+    """Wrapper that preserves permissions and calls `os.stat` after close.
+
+    Two changes on top of AtomicWriter:
+    - Preserve permissions of the file.
+    - Calls `os.stat` after close but before the rename.
+    """
 
     def __init__(self, path, **kwargs):
         super().__init__(path, **kwargs)
         self.stat_result_after_close = None
+        self._permissions = os.stat(path).st_mode
+
+    def get_fileobject(self, **kwargs):
+        f = super().get_fileobject(**kwargs)
+        os.chmod(f.name, mode=self._permissions)
+        return f
 
     def sync(self, f):
         super().sync(f)

beancount_import/journal_editor_test.py

@@ -4,8 +4,10 @@
 from beancount.core.data import Transaction, Posting, EMPTY_SET
 from beancount.core.number import MISSING, Decimal
 from beancount.core.amount import Amount
+import os
 import pytest
 import py
+import stat
 
 from . import journal_editor
 from . import test_util
@@ -139,6 +141,29 @@ def test_simple(tmpdir):
 """)
     check_journal_entries(editor)
 
+def test_permissions(tmpdir):
+    journal_path = create_journal(
+        tmpdir, """
+2015-02-01 * "Test transaction"
+  Assets:Account-A  100 USD
+  Assets:Account-B
+""")
+    # Set unusual permissions. We'll check that they are preserved.
+    os.chmod(journal_path, mode = stat.S_IRUSR | stat.S_IWUSR | stat.S_IXGRP)
+    # In case the OS doesn't support arbitrary inputs to os.chmod,
+    # check what we were actually able to set the mode to.
+    original_mode = os.stat(journal_path).st_mode
+    editor = journal_editor.JournalEditor(journal_path)
+    stage = editor.stage_changes()
+    old_entry = editor.entries[0]
+    new_entry = old_entry._replace(postings=[
+        old_entry.postings[0]._replace(meta=dict(note="Hello")),
+        old_entry.postings[1],
+    ])
+    stage.change_entry(old_entry, new_entry)
+    result = stage.apply()
+    assert os.stat(journal_path).st_mode == original_mode
+
 
 def test_transaction_add_meta(tmpdir):
     journal_path = create_journal(