catch unpacker exceptions, resync, fixes #1351

borg/archive.py

@@ -754,6 +754,9 @@ def valid_msgpacked_dict(d, keys_serialized):
 class RobustUnpacker:
     """A restartable/robust version of the streaming msgpack unpacker
     """
+    class UnpackerCrashed(Exception):
+        """raise if unpacker crashed"""
+
     def __init__(self, validator, item_keys):
         super().__init__()
         self.item_keys = [msgpack.packb(name) for name in item_keys]
@@ -798,7 +801,10 @@ class RobustUnpacker:
                     pass
                 data = data[1:]
         else:
-            return next(self._unpacker)
+            try:
+                return next(self._unpacker)
+            except (TypeError, ValueError) as err:
+                raise self.UnpackerCrashed(str(err))
 
 
 class ArchiveChecker:
@@ -1017,6 +1023,9 @@ class ArchiveChecker:
                                 yield item
                             else:
                                 report('Did not get expected metadata dict when unpacking item metadata', chunk_id, i)
+                    except RobustUnpacker.UnpackerCrashed as err:
+                        report('Unpacker crashed while unpacking item metadata, trying to resync...', chunk_id, i)
+                        unpacker.resync()
                     except Exception:
                         report('Exception while unpacking item metadata', chunk_id, i)
                         raise