From 07f3dd363d9fce66ad53dcdad9f80b72bf3bc1dd 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 | 29 ++++++++++++++++++++++++++---
 wcs/formdef.py        |  7 ++++++-
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/tests/test_formdef.py b/tests/test_formdef.py
index d4ad2e14..e3b44f51 100644
--- a/tests/test_formdef.py
+++ b/tests/test_formdef.py
@@ -259,10 +259,13 @@ def test_internal_identifier_migration(pub):
     formdef.fields = []
     formdef.store()
 
-    obj = pickle.load(open(formdef.get_object_filename(), 'rb'))
+    with open(formdef.get_object_filename(), 'rb') as fd:
+        obj = FormDef.storage_load(fd)
     del obj.internal_identifier
-    pickle.dump(obj, open(formdef.get_object_filename(), 'wb'))
-    assert pickle.load(open(formdef.get_object_filename(), 'rb')).internal_identifier is None
+    with open(formdef.get_object_filename(), 'wb') as fd:
+        fd.write(FormDef.storage_dumps(obj))
+    with open(formdef.get_object_filename(), 'rb') as fd:
+        assert pickle.load(fd).internal_identifier is None
     assert FormDef.get(formdef.id, ignore_migration=True).internal_identifier is None
 
     formdef = FormDef.get(formdef.id)
@@ -621,3 +624,23 @@ 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 880785c9..2855db01 100644
--- a/wcs/formdef.py
+++ b/wcs/formdef.py
@@ -1550,7 +1550,12 @@ 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
+                elif isinstance(o.__dict__.get(b'fields'), list):
+                    pass  # old format
+                else:
+                    raise
         return o
 
     @classmethod
-- 
2.30.0