Fix YAML string loading using Python loader (#86421)

changelogs/fragments/pyyaml-name.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - yaml loading - Fix traceback when parsing YAML strings (not files) when using the pure Python implementation of PyYAML.

lib/ansible/_internal/_yaml/_loader.py

@@ -13,22 +13,20 @@ from ._constructor import AnsibleConstructor, AnsibleInstrumentedConstructor
 if HAS_LIBYAML:
     from yaml.cyaml import CParser
 
-    class _YamlParser(CParser):
+    class _Parser(CParser):
         def __init__(self, stream: str | bytes | _io.IOBase) -> None:
             if isinstance(stream, (str, bytes)):
                 stream = AnsibleTagHelper.untag(stream)  # PyYAML + libyaml barfs on str/bytes subclasses
 
             CParser.__init__(self, stream)
 
-            self.name = getattr(stream, 'name', None)  # provide feature parity with the Python implementation (yaml.reader.Reader provides name)
-
 else:
     from yaml.composer import Composer
     from yaml.reader import Reader
     from yaml.scanner import Scanner
     from yaml.parser import Parser
 
-    class _YamlParser(Reader, Scanner, Parser, Composer):  # type: ignore[no-redef]
+    class _Parser(Reader, Scanner, Parser, Composer):  # type: ignore[no-redef]
         def __init__(self, stream: str | bytes | _io.IOBase) -> None:
             Reader.__init__(self, stream)
             Scanner.__init__(self)
@@ -36,6 +34,17 @@ else:
             Composer.__init__(self)
 
 
+class _YamlParser(_Parser):
+    def __init__(self, stream: str | bytes | _io.IOBase) -> None:
+        super().__init__(stream)
+
+        # The Python implementation of PyYAML (yaml.reader.Reader) provides self.name.
+        # However, it will fall back to "<...>" in various cases.
+        # The C implementation of PyYAML does not provide self.name.
+        # To provide consistency, name retrieval is re-implemented here.
+        self.name = getattr(stream, 'name', None)
+
+
 class AnsibleInstrumentedLoader(_YamlParser, AnsibleInstrumentedConstructor, Resolver):
     """Ansible YAML loader which supports Ansible custom behavior such as `Origin` tagging, but no Ansible-specific YAML tags."""
 

test/integration/targets/pyyaml/runme.sh

@@ -4,8 +4,18 @@ set -eu -o pipefail
 source virtualenv.sh
 set +x
 
+# Verify libyaml is in use.
+ansible --version | tee /dev/stderr | grep 'with libyaml'
+
+# Run tests with libyaml.
+ansible-playbook runme.yml "${@}"
+
 # deps are already installed, using --no-deps to avoid re-installing them
 # Install PyYAML without libyaml to validate ansible can run
 PYYAML_FORCE_LIBYAML=0 pip install --no-binary PyYAML --ignore-installed --no-cache-dir --no-deps PyYAML
 
+# Verify libyaml is not in use.
 ansible --version | tee /dev/stderr | grep 'without libyaml'
+
+# Run tests without libyaml.
+ansible-playbook runme.yml "${@}"

test/integration/targets/pyyaml/runme.yml

@@ -0,0 +1,9 @@
+- hosts: localhost
+  gather_facts: no
+  tasks:
+    - name: Read YAML from a string
+      assert:
+        that:
+          - "'1' | from_yaml == 1"
+          - "'[1]' | from_yaml == [1]"
+          - "'key: value' | from_yaml == {'key': 'value'}"