From 2225e431d6a8702495bf6432ba4bf1f8bc6a0742 Mon Sep 17 00:00:00 2001
From: Benjamin Dauvergne <bdauvergne@entrouvert.com>
Date: Mon, 22 Feb 2021 23:30:20 +0100
Subject: [PATCH 2/3] formdef: prevent hiding of EOFError on new style pickled
 formdef (#51327)

---
 tests/test_formdef.py | 20 ++++++++++++++++++++
 wcs/formdef.py        |  5 ++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/tests/test_formdef.py b/tests/test_formdef.py
index b54b3fe5..6578ed40 100644
--- a/tests/test_formdef.py
+++ b/tests/test_formdef.py
@@ -622,3 +622,23 @@ def test_pickle_2to3_conversion(pub):
     assert formdef.fields[0].label == 'Test'
     assert formdef.workflow.possible_status[0].items[0].varname == 'blah'
     assert formdef.workflow.possible_status[0].items[0].formdef.fields[0].varname == 'str'
+
+
+def test_lightweight(pub):
+    FormDef.wipe()
+    formdef = FormDef()
+    formdef.name = 'basic formdef'
+    formdef.fields = [
+        StringField(id='1', label='Test', type='string', varname='foo'),
+    ]
+    formdef.store()
+
+    # load works
+    FormDef.get(formdef.id)
+
+    # truncate the pickle, now load should fail
+    with open(formdef.get_object_filename(), 'rb+') as fd:
+        pickle.load(fd)
+        fd.truncate(fd.tell())
+    with pytest.raises(KeyError):
+        FormDef.get(formdef.id)
diff --git a/wcs/formdef.py b/wcs/formdef.py
index 7bede6b7..b11d9c37 100644
--- a/wcs/formdef.py
+++ b/wcs/formdef.py
@@ -1551,7 +1551,10 @@ class FormDef(StorableObject):
             try:
                 o.fields = pickle.load(fd, **PICKLE_KWARGS)
             except EOFError:
-                pass  # old format
+                if isinstance(getattr(o, 'fields', None), list):
+                    pass  # old format
+                else:
+                    raise
         return o
 
     @classmethod
-- 
2.30.0