catch incomplete trailing header in tolerant recovery

This makes decryption in recovery mode resistant against
malformed trailing data which would otherwise error out for the
entire buffered chunk on account of a decryption failure.

diff --git a/deltatar/deltatar.py b/deltatar/deltatar.py
index 1b15a0a..9a96467 100644 (file)
--- a/deltatar/deltatar.py
+++ b/deltatar/deltatar.py
@@ -1382,7 +1382,7 @@ class DeltaTar(object):
             helper = RestoreHelper(self, cwd, backup_path=backup_tar_path,
                                    tarobj=index_it.tar_obj)
         elif mode == "diff":
-            helper = RestoreHelper(self, cwd, backup_indexes_paths)
+            helper = RestoreHelper(self, cwd, backup_indexes_paths, disaster=disaster)
             # get iterator from newest index at _data[0]
             index_it = self.iterate_index_path(helper._data[0]["path"])
 
@@ -1861,7 +1861,8 @@ class RestoreHelper(object):
                     concat='#' in self._deltatar.mode,
                     encryption=index_data["decryptor"],
                     new_volume_handler=index_data['new_volume_handler'],
-                    save_to_members=False)
+                    save_to_members=False,
+                    tolerant=self._disaster)
 
                 member = index_data['tarobj'].__iter__().__next__()
 

diff --git a/deltatar/tarfile.py b/deltatar/tarfile.py
index 49678cc..2629e44 100644 (file)
--- a/deltatar/tarfile.py
+++ b/deltatar/tarfile.py
@@ -1017,9 +1017,15 @@ class _Stream:
             if self.arcmode & ARCMODE_ENCRYPT:
                 if self.remainder <= 0:
                     # prepare next object
-                    if self._init_read_encrypt () is False: # EOF
-                        buf = None
-                        break # while
+                    try:
+                        if self._init_read_encrypt () is False: # EOF
+                            buf = None
+                            break # while
+                    except DecryptionError:
+                        if self.tolerant:
+                            self.buf = b"".join (t [good_crypto:])
+                            return b"".join (t [:good_crypto])
+                        raise
 
                 # only read up to the end of the encrypted object
                 todo = min (size, self.remainder)
@@ -2072,7 +2078,7 @@ class TarFile(object):
 
     @classmethod
     def open(cls, name=None, mode="r", fileobj=None, bufsize=RECORDSIZE,
-             encryption=None, compresslevel=9, **kwargs):
+             encryption=None, compresslevel=9, tolerant=False, **kwargs):
         """Open a tar archive for reading, writing or appending. Return
            an appropriate TarFile class.
 
@@ -2169,7 +2175,7 @@ class TarFile(object):
 
             stream = _Stream(name, filemode, comptype, fileobj, bufsize,
                              concat=True, encryption=encryption,
-                             compresslevel=compresslevel)
+                             compresslevel=compresslevel, tolerant=tolerant)
             kwargs ["concat"] = True
             try:
                 t = cls(name, filemode, stream, **kwargs)