From edea587f3586974dfd50fa56899d7afef6c50375 Mon Sep 17 00:00:00 2001
From: Thomas Waldmann <tw@waldmann-edv.de>
Date: Thu, 28 Jul 2016 22:10:29 +0200
Subject: [PATCH 1/3] catch unpacker exceptions, resync, fixes #1351

---
 borg/archive.py | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/borg/archive.py b/borg/archive.py
index 9964f5f27..ac7d77565 100644
--- a/borg/archive.py
+++ b/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

From 852c583076efa8fbc29d576b2cd3c932b7f9c726 Mon Sep 17 00:00:00 2001
From: Thomas Waldmann <tw@waldmann-edv.de>
Date: Thu, 28 Jul 2016 22:12:34 +0200
Subject: [PATCH 2/3] handle unpacker exception with tighter scope

---
 borg/archive.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/borg/archive.py b/borg/archive.py
index ac7d77565..854544779 100644
--- a/borg/archive.py
+++ b/borg/archive.py
@@ -792,13 +792,14 @@ class RobustUnpacker:
                 self._unpacker.feed(data)
                 try:
                     item = next(self._unpacker)
+                except (TypeError, ValueError, StopIteration):
+                    # Ignore exceptions that might be raised when feeding
+                    # msgpack with invalid data
+                    pass
+                else:
                     if self.validator(item):
                         self._resync = False
                         return item
-                # Ignore exceptions that might be raised when feeding
-                # msgpack with invalid data
-                except (TypeError, ValueError, StopIteration):
-                    pass
                 data = data[1:]
         else:
             try:

From 97383e9e6051dd174b588a18e67aff65acc7b5b6 Mon Sep 17 00:00:00 2001
From: Thomas Waldmann <tw@waldmann-edv.de>
Date: Thu, 28 Jul 2016 22:23:38 +0200
Subject: [PATCH 3/3] transform unpacker exception only at 1 place

---
 borg/archive.py | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/borg/archive.py b/borg/archive.py
index 854544779..653e2dd1c 100644
--- a/borg/archive.py
+++ b/borg/archive.py
@@ -779,6 +779,14 @@ class RobustUnpacker:
         return self
 
     def __next__(self):
+        def unpack_next():
+            try:
+                return next(self._unpacker)
+            except (TypeError, ValueError) as err:
+                # transform exceptions that might be raised when feeding
+                # msgpack with invalid data to a more specific exception
+                raise self.UnpackerCrashed(str(err))
+
         if self._resync:
             data = b''.join(self._buffered_data)
             while self._resync:
@@ -791,10 +799,9 @@ class RobustUnpacker:
                 self._unpacker = msgpack.Unpacker(object_hook=StableDict)
                 self._unpacker.feed(data)
                 try:
-                    item = next(self._unpacker)
-                except (TypeError, ValueError, StopIteration):
-                    # Ignore exceptions that might be raised when feeding
-                    # msgpack with invalid data
+                    item = unpack_next()
+                except (self.UnpackerCrashed, StopIteration):
+                    # as long as we are resyncing, we also ignore StopIteration
                     pass
                 else:
                     if self.validator(item):
@@ -802,10 +809,7 @@ class RobustUnpacker:
                         return item
                 data = data[1:]
         else:
-            try:
-                return next(self._unpacker)
-            except (TypeError, ValueError) as err:
-                raise self.UnpackerCrashed(str(err))
+            return unpack_next()
 
 
 class ArchiveChecker: