Merge lp:~mterry/duplicity/guard-tarinfo into lp:duplicity/0.6

[Michael Terry]

A deja-dup user described a duplicity traceback that seemed preventable:

https://bugs.launchpad.net/ubuntu/+source/deja-dup/+bug/616482/comments/3

Here's a fix. It's not clear that this will help the user (something else is likely wrong for us to get to this point), but it will presumably allow them to get further.

Since _proc_gnulong() can return None, it's output needs to be checked before being used.

=== modified file 'duplicity/tarfile.py'
--- duplicity/tarfile.py	2010-07-22 19:15:11 +0000
+++ duplicity/tarfile.py	2011-06-23 15:50:58 +0000
@@ -562,6 +562,8 @@
         # statement, we must process this first.
         if tarinfo.type in (GNUTYPE_LONGLINK, GNUTYPE_LONGNAME):
             tarinfo = self._proc_gnulong(tarinfo, tarinfo.type)
+            if not tarinfo:
+                return None
 
         if tarinfo.issparse():
             assert 0, "Sparse file support turned off"
@@ -1111,6 +1113,7 @@
         tarinfo = self._buftoinfo(buf)
         if tarinfo.type in (GNUTYPE_LONGLINK, GNUTYPE_LONGNAME):
             tarinfo = self._proc_gnulong(tarinfo, tarinfo.type)
+            if not tarinfo: return None
         if name is not None:
             tarinfo.name = name
         if linkname is not None: