Merge pull request #54 from wwkimball/bugfix/ruamel-yaml-crash-wipes-…

…out-files-on-set

Bugfix/ruamel yaml crash wipes out files on set

CHANGES

@@ -1,3 +1,11 @@
+2.3.5:
+Bug Fixes:
+* Certain YAML constructs trigger AssertionErrors in ruamel.yaml during YAML
+  data writes.  This was causing yaml-set to generate empty files.  Until
+  https://sourceforge.net/p/ruamel-yaml/tickets/351/ is fixed, this patch
+  will revert the file contents to mitigate data loss under these conditions.
+  A specific test has been created to detect when the upstream issue is fixed.
+
 2.3.4:
 Bug Fixes:
 * Minor security patch:  Python already makes non-shell subprocess calls safe

setup.py

@@ -5,7 +5,7 @@
 
 setuptools.setup(
     name="yamlpath",
-    version="2.3.4",
+    version="2.3.5",
     description="Read and change YAML/Compatible data using powerful, intuitive, command-line friendly syntax",
     long_description=long_description,
     long_description_content_type="text/markdown",

tests/test_commands_yaml_set.py

@@ -434,7 +434,6 @@ def test_replace_backup_file(self, script_runner, tmp_path_factory):
             filedat = fhnd.read()
         assert filedat == content
 
-
     def test_nonref_changes(self, script_runner, tmp_path_factory):
         yamlin = """---
 somestring:
@@ -468,3 +467,35 @@ def test_nonref_changes(self, script_runner, tmp_path_factory):
         with open(yaml_file, 'r') as fhnd:
             filedat = fhnd.read()
         assert filedat == yamlout
+
+    @pytest.mark.xfail(strict=True, reason="https://sourceforge.net/p/ruamel-yaml/tickets/351/")
+    def test_commented_aliased_parent_hash(self, script_runner, tmp_path_factory):
+        yamlin = """---
+aliases:
+  - &key_alias hash
+
+*key_alias :
+  # Comment
+  key: value
+"""
+        yamlout = """---
+aliases:
+  - &key_alias hash
+
+*key_alias :
+  # Comment
+  key: new value
+"""
+        yaml_file = create_temp_yaml_file(tmp_path_factory, yamlin)
+        result = script_runner.run(
+            self.command,
+            "--change=/hash/key",
+            "--value=new value",
+            "--backup",
+            yaml_file
+        )
+        assert result.success, result.stderr
+
+        with open(yaml_file, 'r') as fhnd:
+            filedat = fhnd.read()
+        assert filedat == yamlout

yamlpath/commands/yaml_set.py

@@ -10,12 +10,13 @@
 Copyright 2018, 2019, 2020 William W. Kimball, Jr. MBA MSIS
 """
 import sys
+import tempfile
 import argparse
 import secrets
 import string
 from os import remove, access, R_OK
 from os.path import isfile, exists
-from shutil import copy2
+from shutil import copy2, copyfileobj
 
 from yamlpath.func import clone_node, get_yaml_data, get_yaml_editor
 from yamlpath import YAMLPath
@@ -335,8 +336,28 @@ def main():
 
     # Save the changed file
     log.verbose("Writing changed data to {}.".format(args.yaml_file))
-    with open(args.yaml_file, 'w') as yaml_dump:
-        yaml.dump(yaml_data, yaml_dump)
+    with tempfile.TemporaryFile() as tmphnd:
+        with open(args.yaml_file, 'rb') as inhnd:
+            copyfileobj(inhnd, tmphnd)
+
+        with open(args.yaml_file, 'w') as yaml_dump:
+            try:
+                yaml.dump(yaml_data, yaml_dump)
+            except AssertionError as ex:
+                yaml_dump.close()
+                tmphnd.seek(0)
+                with open(args.yaml_file, 'wb') as outhnd:
+                    copyfileobj(tmphnd, outhnd)
+
+                # No sense in preserving a backup file with no changes
+                if args.backup:
+                    remove(backup_file)
+
+                log.debug("Assertion error: {}".format(ex))
+                log.critical((
+                    "Indeterminate assertion error encountered while"
+                    + " attempting to write updated data to {}.  The original"
+                    + " file content was restored.").format(args.yaml_file), 3)
 
 if __name__ == "__main__":
     main()  # pragma: no cover

yamlpath/processor.py

@@ -689,7 +689,12 @@ def _get_optional_nodes(
         # pylint: disable=locally-disabled,too-many-nested-blocks
         if segments and len(segments) > depth:
             (segment_type, unstripped_attrs) = yaml_path.unescaped[depth]
-            stripped_attrs = segments[depth][1]
+            stripped_attrs: Union[
+                str,
+                int,
+                SearchTerms,
+                CollectorTerms
+            ] = segments[depth][1]
             except_segment = str(unstripped_attrs)
 
             self.logger.debug(