Split of metadata encoding for fmt6 and general stuff

11 files changed, 248 insertions, 203 deletions

diff --git a/metadata-speed b/metadata-speed
index 23cb1825..51d94405 100755
--- a/metadata-speed
+++ b/metadata-speed
@@ -37,10 +37,12 @@ def main():
     fs = obnamlib.LocalFS('.')
     fs.connect()
     metadata = obnamlib.read_metadata(fs, '.')
-    encoded = obnamlib.encode_metadata(metadata)
+    encoded = obnamlib.fmt_6.metadata_codec.encode_metadata(metadata)
     calibrate = measure(n, lambda: None)
-    encode = measure(n, lambda: obnamlib.encode_metadata(metadata))
-    decode = measure(n, lambda: obnamlib.decode_metadata(encoded))
+    encode = measure(
+        n, lambda: obnamlib.fmt_6.metadata_codec.encode_metadata(metadata))
+    decode = measure(
+        n, lambda: obnamlib.fmt_6.metadata_codec.decode_metadata(encoded))
     print 'encode: %.1f s' % (n/(encode - calibrate))
     print 'decode: %.1f s' % (n/(decode - calibrate))
 
diff --git a/obnamlib/__init__.py b/obnamlib/__init__.py
index 70c3ee57..b70a4174 100644
--- a/obnamlib/__init__.py
+++ b/obnamlib/__init__.py
@@ -154,14 +154,11 @@ from repo_dummy import RepositoryFormatDummy
 # Repository format 6 specific modules.
 #
 
-from fmt_6.metadata import (
+from metadata import (
     Metadata,
     read_metadata,
     set_metadata,
-    metadata_fields,
-    metadata_verify_fields,
-    encode_metadata,
-    decode_metadata)
+    metadata_fields)
 from fmt_6.repo_fmt_6 import RepositoryFormat6
 from fmt_6.repo_tree import RepositoryTree
 from fmt_6.chunklist import ChunkList
diff --git a/obnamlib/fmt_6/__init__.py b/obnamlib/fmt_6/__init__.py
index e69de29b..bfad0228 100644
--- a/obnamlib/fmt_6/__init__.py
+++ b/obnamlib/fmt_6/__init__.py
@@ -0,0 +1 @@
+import metadata_codec
diff --git a/obnamlib/fmt_6/clientmetadatatree.py b/obnamlib/fmt_6/clientmetadatatree.py
index 1019f71b..375ec8f0 100644
--- a/obnamlib/fmt_6/clientmetadatatree.py
+++ b/obnamlib/fmt_6/clientmetadatatree.py
@@ -356,9 +356,10 @@ class ClientMetadataTree(obnamlib.RepositoryTree):
         except KeyError:
             old_metadata = None
         else: # pragma: no cover
-            old = obnamlib.decode_metadata(old_metadata)
+            old = obnamlib.fmt_6.metadata_codec.decode_metadata(old_metadata)
 
-        metadata = obnamlib.decode_metadata(encoded_metadata)
+        metadata = obnamlib.fmt_6.metadata_codec.decode_metadata(
+            encoded_metadata)
 
         if encoded_metadata != old_metadata:
             tracing.trace('new or changed metadata')
@@ -409,7 +410,8 @@ class ClientMetadataTree(obnamlib.RepositoryTree):
         except KeyError:
             pass
         else:
-            metadata = obnamlib.decode_metadata(encoded_metadata)
+            metadata = obnamlib.fmt_6.metadata_codec.decode_metadata(
+                encoded_metadata)
 
         # Remove any children.
         minkey = self.fskey(file_id, self.DIR_CONTENTS, 0)
diff --git a/obnamlib/fmt_6/clientmetadatatree_tests.py b/obnamlib/fmt_6/clientmetadatatree_tests.py
index 07bf92ae..4fc67a90 100644
--- a/obnamlib/fmt_6/clientmetadatatree_tests.py
+++ b/obnamlib/fmt_6/clientmetadatatree_tests.py
@@ -41,7 +41,8 @@ class ClientMetadataTreeTests(unittest.TestCase):
         self.file_size = 123
         self.file_metadata = obnamlib.Metadata(st_mode=stat.S_IFREG | 0666,
                                                st_size=self.file_size)
-        self.file_encoded = obnamlib.encode_metadata(self.file_metadata)
+        self.file_encoded = obnamlib.fmt_6.metadata_codec.encode_metadata(
+            self.file_metadata)
 
     def tearDown(self):
         shutil.rmtree(self.tempdir)
@@ -155,9 +156,11 @@ class ClientMetadataTreeFileOpsTests(unittest.TestCase):
         self.client.start_generation()
         self.clientid = self.client.get_generation_id(self.client.tree)
         self.file_metadata = obnamlib.Metadata(st_mode=stat.S_IFREG | 0666)
-        self.file_encoded = obnamlib.encode_metadata(self.file_metadata)
+        self.file_encoded = obnamlib.fmt_6.metadata_codec.encode_metadata(
+            self.file_metadata)
         self.dir_metadata = obnamlib.Metadata(st_mode=stat.S_IFDIR | 0777)
-        self.dir_encoded = obnamlib.encode_metadata(self.dir_metadata)
+        self.dir_encoded = obnamlib.fmt_6.metadata_codec.encode_metadata(
+            self.dir_metadata)
 
     def tearDown(self):
         shutil.rmtree(self.tempdir)
diff --git a/obnamlib/fmt_6/metadata_codec.py b/obnamlib/fmt_6/metadata_codec.py
new file mode 100644
index 00000000..93c93bdb
--- /dev/null
+++ b/obnamlib/fmt_6/metadata_codec.py
@@ -0,0 +1,136 @@
+# Copyright (C) 2009-2014  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import struct
+
+import obnamlib
+
+
+metadata_format = struct.Struct('!Q' +  # flags
+                                'Q' +   # st_mode
+                                'qQ' +  # st_mtime_sec and _nsec
+                                'qQ' +  # st_atime_sec and _nsec
+                                'Q' +   # st_nlink
+                                'Q' +   # st_size
+                                'Q' +   # st_uid
+                                'Q' +   # st_gid
+                                'Q' +   # st_dev
+                                'Q' +   # st_ino
+                                'Q' +   # st_blocks
+                                'Q' +   # len of groupname
+                                'Q' +   # len of username
+                                'Q' +   # len of symlink target
+                                'Q' +   # len of md5
+                                'Q' +   # len of xattr
+                                '')
+
+def encode_metadata(metadata):
+    flags = 0
+    for i, name in enumerate(obnamlib.metadata_fields):
+        if getattr(metadata, name) is not None:
+            flags |= (1 << i)
+
+    try:
+        packed = metadata_format.pack(flags,
+                                      metadata.st_mode or 0,
+                                      metadata.st_mtime_sec or 0,
+                                      metadata.st_mtime_nsec or 0,
+                                      metadata.st_atime_sec or 0,
+                                      metadata.st_atime_nsec or 0,
+                                      metadata.st_nlink or 0,
+                                      metadata.st_size or 0,
+                                      metadata.st_uid or 0,
+                                      metadata.st_gid or 0,
+                                      metadata.st_dev or 0,
+                                      metadata.st_ino or 0,
+                                      metadata.st_blocks or 0,
+                                      len(metadata.groupname or ''),
+                                      len(metadata.username or ''),
+                                      len(metadata.target or ''),
+                                      len(metadata.md5 or ''),
+                                      len(metadata.xattr or ''))
+    except TypeError, e: # pragma: no cover
+        logging.error('ERROR: Packing error due to %s' % str(e))
+        logging.error('ERROR: st_mode=%s' % repr(metadata.st_mode))
+        logging.error('ERROR: st_mtime_sec=%s' % repr(metadata.st_mtime_sec))
+        logging.error('ERROR: st_mtime_nsec=%s' % repr(metadata.st_mtime_nsec))
+        logging.error('ERROR: st_atime_sec=%s' % repr(metadata.st_atime_sec))
+        logging.error('ERROR: st_atime_nsec=%s' % repr(metadata.st_atime_nsec))
+        logging.error('ERROR: st_nlink=%s' % repr(metadata.st_nlink))
+        logging.error('ERROR: st_size=%s' % repr(metadata.st_size))
+        logging.error('ERROR: st_uid=%s' % repr(metadata.st_uid))
+        logging.error('ERROR: st_gid=%s' % repr(metadata.st_gid))
+        logging.error('ERROR: st_dev=%s' % repr(metadata.st_dev))
+        logging.error('ERROR: st_ino=%s' % repr(metadata.st_ino))
+        logging.error('ERROR: st_blocks=%s' % repr(metadata.st_blocks))
+        logging.error('ERROR: groupname=%s' % repr(metadata.groupname))
+        logging.error('ERROR: username=%s' % repr(metadata.username))
+        logging.error('ERROR: target=%s' % repr(metadata.target))
+        logging.error('ERROR: md5=%s' % repr(metadata.md5))
+        logging.error('ERROR: xattr=%s' % repr(metadata.xattr))
+        raise
+    return (packed +
+             (metadata.groupname or '') +
+             (metadata.username or '') +
+             (metadata.target or '') +
+             (metadata.md5 or '') +
+             (metadata.xattr or ''))
+
+
+def decode_metadata(encoded):
+
+    items = metadata_format.unpack_from(encoded)
+    flags = items[0]
+    pos = [1, metadata_format.size]
+    metadata = obnamlib.Metadata()
+
+    def is_present(field):
+        i = obnamlib.metadata_fields.index(field)
+        return (flags & (1 << i)) != 0
+
+    def decode(field, num_items, inc_offset, getvalue):
+        if is_present(field):
+            value = getvalue(pos[0], pos[1])
+            setattr(metadata, field, value)
+            if inc_offset:
+                pos[1] += len(value)
+        pos[0] += num_items
+
+    def decode_integer(field):
+        decode(field, 1, False, lambda i, o: items[i])
+
+    def decode_string(field):
+        decode(field, 1, True, lambda i, o: encoded[o:o + items[i]])
+
+    decode_integer('st_mode')
+    decode_integer('st_mtime_sec')
+    decode_integer('st_mtime_nsec')
+    decode_integer('st_atime_sec')
+    decode_integer('st_atime_nsec')
+    decode_integer('st_nlink')
+    decode_integer('st_size')
+    decode_integer('st_uid')
+    decode_integer('st_gid')
+    decode_integer('st_dev')
+    decode_integer('st_ino')
+    decode_integer('st_blocks')
+    decode_string('groupname')
+    decode_string('username')
+    decode_string('target')
+    decode_string('md5')
+    decode_string('xattr')
+
+    return metadata
diff --git a/obnamlib/fmt_6/metadata_codec_tests.py b/obnamlib/fmt_6/metadata_codec_tests.py
new file mode 100644
index 00000000..47f8b312
--- /dev/null
+++ b/obnamlib/fmt_6/metadata_codec_tests.py
@@ -0,0 +1,85 @@
+# Copyright (C) 2009-2014  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import unittest
+
+import obnamlib
+
+
+class MetadataCodingTests(unittest.TestCase):
+
+    def equal(self, meta1, meta2):
+        for name in dir(meta1):
+            if name in obnamlib.metadata_fields:
+                value1 = getattr(meta1, name)
+                value2 = getattr(meta2, name)
+                self.assertEqual(
+                    value1,
+                    value2,
+                    'attribute %s must be equal (%s vs %s)' %
+                        (name, value1, value2))
+
+    def test_round_trip(self):
+        metadata = obnamlib.Metadata(
+            st_mode=1,
+            st_mtime_sec=2,
+            st_mtime_nsec=12756,
+            st_nlink=3,
+            st_size=4,
+            st_uid=5,
+            st_blocks=6,
+            st_dev=7,
+            st_gid=8,
+            st_ino=9,
+            st_atime_sec=10,
+            st_atime_nsec=123,
+            groupname='group',
+            username='user',
+            target='target',
+            md5='checksum')
+        encoded = obnamlib.fmt_6.metadata_codec.encode_metadata(metadata)
+        decoded = obnamlib.fmt_6.metadata_codec.decode_metadata(encoded)
+        self.equal(metadata, decoded)
+
+    def test_round_trip_for_None_values(self):
+        metadata = obnamlib.Metadata()
+        encoded = obnamlib.fmt_6.metadata_codec.encode_metadata(metadata)
+        decoded = obnamlib.fmt_6.metadata_codec.decode_metadata(encoded)
+        for name in dir(metadata):
+            if name in obnamlib.metadata_fields:
+                self.assertEqual(getattr(decoded, name), None,
+                                 'attribute %s must be None' % name)
+
+    def test_round_trip_for_maximum_values(self):
+        unsigned_max = 2**64 - 1
+        signed_max = 2**63 - 1
+        metadata = obnamlib.Metadata(
+            st_mode=unsigned_max,
+            st_mtime_sec=signed_max,
+            st_mtime_nsec=unsigned_max,
+            st_nlink=unsigned_max,
+            st_size=signed_max,
+            st_uid=unsigned_max,
+            st_blocks=signed_max,
+            st_dev=unsigned_max,
+            st_gid=unsigned_max,
+            st_ino=unsigned_max,
+            st_atime_sec=signed_max,
+            st_atime_nsec=unsigned_max)
+        encoded = obnamlib.fmt_6.metadata_codec.encode_metadata(metadata)
+        decoded = obnamlib.fmt_6.metadata_codec.decode_metadata(encoded)
+        self.equal(metadata, decoded)
+
diff --git a/obnamlib/fmt_6/repo_fmt_6.py b/obnamlib/fmt_6/repo_fmt_6.py
index df06eacb..185e9ed5 100644
--- a/obnamlib/fmt_6/repo_fmt_6.py
+++ b/obnamlib/fmt_6/repo_fmt_6.py
@@ -847,7 +847,8 @@ class RepositoryFormat6(obnamlib.RepositoryInterface):
         client_name, gen_number = self._unpack_gen_id(generation_id)
         self._require_client_lock(client_name)
         client = self._open_client(client_name)
-        encoded_metadata = obnamlib.encode_metadata(obnamlib.Metadata())
+        encoded_metadata = obnamlib.fmt_6.metadata_codec.encode_metadata(
+            obnamlib.Metadata())
         client.create(filename, encoded_metadata)
 
     def remove_file(self, generation_id, filename):
@@ -883,7 +884,8 @@ class RepositoryFormat6(obnamlib.RepositoryInterface):
             client_name, generation_number = self._unpack_gen_id(generation_id)
             dirty, metadata = value
             if dirty:
-                encoded_metadata = obnamlib.encode_metadata(metadata)
+                encoded_metadata = \
+                    obnamlib.fmt_6.metadata_codec.encode_metadata(metadata)
                 client = self._open_client(client_name)
                 # FIXME: Only sets in unfinished generation
                 client.set_metadata(filename, encoded_metadata)
@@ -893,7 +895,8 @@ class RepositoryFormat6(obnamlib.RepositoryInterface):
         client_name, gen_number = self._unpack_gen_id(generation_id)
         client = self._open_client(client_name)
         encoded_metadata = client.get_metadata(gen_number, filename)
-        metadata = obnamlib.decode_metadata(encoded_metadata)
+        metadata = obnamlib.fmt_6.metadata_codec.decode_metadata(
+            encoded_metadata)
         cache_key = self._get_file_key_cache_key(generation_id, filename)
         self._file_key_cache[cache_key] = (False, metadata)
 
diff --git a/obnamlib/fmt_6/metadata.py b/obnamlib/metadata.py
index 61daa655..1dea8dfc 100644
--- a/obnamlib/fmt_6/metadata.py
+++ b/obnamlib/metadata.py
@@ -265,121 +265,3 @@ def set_metadata(fs, filename, metadata,
 
     fs.lutimes(filename, metadata.st_atime_sec, metadata.st_atime_nsec,
                metadata.st_mtime_sec, metadata.st_mtime_nsec)
-
-
-metadata_format = struct.Struct('!Q' +  # flags
-                                'Q' +   # st_mode
-                                'qQ' +  # st_mtime_sec and _nsec
-                                'qQ' +  # st_atime_sec and _nsec
-                                'Q' +   # st_nlink
-                                'Q' +   # st_size
-                                'Q' +   # st_uid
-                                'Q' +   # st_gid
-                                'Q' +   # st_dev
-                                'Q' +   # st_ino
-                                'Q' +   # st_blocks
-                                'Q' +   # len of groupname
-                                'Q' +   # len of username
-                                'Q' +   # len of symlink target
-                                'Q' +   # len of md5
-                                'Q' +   # len of xattr
-                                '')
-
-def encode_metadata(metadata):
-    flags = 0
-    for i, name in enumerate(obnamlib.metadata_fields):
-        if getattr(metadata, name) is not None:
-            flags |= (1 << i)
-
-    try:
-        packed = metadata_format.pack(flags,
-                                      metadata.st_mode or 0,
-                                      metadata.st_mtime_sec or 0,
-                                      metadata.st_mtime_nsec or 0,
-                                      metadata.st_atime_sec or 0,
-                                      metadata.st_atime_nsec or 0,
-                                      metadata.st_nlink or 0,
-                                      metadata.st_size or 0,
-                                      metadata.st_uid or 0,
-                                      metadata.st_gid or 0,
-                                      metadata.st_dev or 0,
-                                      metadata.st_ino or 0,
-                                      metadata.st_blocks or 0,
-                                      len(metadata.groupname or ''),
-                                      len(metadata.username or ''),
-                                      len(metadata.target or ''),
-                                      len(metadata.md5 or ''),
-                                      len(metadata.xattr or ''))
-    except TypeError, e: # pragma: no cover
-        logging.error('ERROR: Packing error due to %s' % str(e))
-        logging.error('ERROR: st_mode=%s' % repr(metadata.st_mode))
-        logging.error('ERROR: st_mtime_sec=%s' % repr(metadata.st_mtime_sec))
-        logging.error('ERROR: st_mtime_nsec=%s' % repr(metadata.st_mtime_nsec))
-        logging.error('ERROR: st_atime_sec=%s' % repr(metadata.st_atime_sec))
-        logging.error('ERROR: st_atime_nsec=%s' % repr(metadata.st_atime_nsec))
-        logging.error('ERROR: st_nlink=%s' % repr(metadata.st_nlink))
-        logging.error('ERROR: st_size=%s' % repr(metadata.st_size))
-        logging.error('ERROR: st_uid=%s' % repr(metadata.st_uid))
-        logging.error('ERROR: st_gid=%s' % repr(metadata.st_gid))
-        logging.error('ERROR: st_dev=%s' % repr(metadata.st_dev))
-        logging.error('ERROR: st_ino=%s' % repr(metadata.st_ino))
-        logging.error('ERROR: st_blocks=%s' % repr(metadata.st_blocks))
-        logging.error('ERROR: groupname=%s' % repr(metadata.groupname))
-        logging.error('ERROR: username=%s' % repr(metadata.username))
-        logging.error('ERROR: target=%s' % repr(metadata.target))
-        logging.error('ERROR: md5=%s' % repr(metadata.md5))
-        logging.error('ERROR: xattr=%s' % repr(metadata.xattr))
-        raise
-    return (packed +
-             (metadata.groupname or '') +
-             (metadata.username or '') +
-             (metadata.target or '') +
-             (metadata.md5 or '') +
-             (metadata.xattr or ''))
-
-
-def decode_metadata(encoded):
-
-    items = metadata_format.unpack_from(encoded)
-    flags = items[0]
-    pos = [1, metadata_format.size]
-    metadata = obnamlib.Metadata()
-
-    def is_present(field):
-        i = obnamlib.metadata_fields.index(field)
-        return (flags & (1 << i)) != 0
-
-    def decode(field, num_items, inc_offset, getvalue):
-        if is_present(field):
-            value = getvalue(pos[0], pos[1])
-            setattr(metadata, field, value)
-            if inc_offset:
-                pos[1] += len(value)
-        pos[0] += num_items
-
-    def decode_integer(field):
-        decode(field, 1, False, lambda i, o: items[i])
-
-    def decode_string(field):
-        decode(field, 1, True, lambda i, o: encoded[o:o + items[i]])
-
-    decode_integer('st_mode')
-    decode_integer('st_mtime_sec')
-    decode_integer('st_mtime_nsec')
-    decode_integer('st_atime_sec')
-    decode_integer('st_atime_nsec')
-    decode_integer('st_nlink')
-    decode_integer('st_size')
-    decode_integer('st_uid')
-    decode_integer('st_gid')
-    decode_integer('st_dev')
-    decode_integer('st_ino')
-    decode_integer('st_blocks')
-    decode_string('groupname')
-    decode_string('username')
-    decode_string('target')
-    decode_string('md5')
-    decode_string('xattr')
-
-    return metadata
-
diff --git a/obnamlib/fmt_6/metadata_tests.py b/obnamlib/metadata_tests.py
index 49376dd9..9ee15f41 100644
--- a/obnamlib/fmt_6/metadata_tests.py
+++ b/obnamlib/metadata_tests.py
@@ -248,69 +248,3 @@ class SetMetadataTests(unittest.TestCase):
 
         self.assertEqual(st.st_mode & stat.S_ISUID, stat.S_ISUID)
         self.assertEqual(st.st_mode & stat.S_ISGID, stat.S_ISGID)
-
-
-class MetadataCodingTests(unittest.TestCase):
-
-    def equal(self, meta1, meta2):
-        for name in dir(meta1):
-            if name in obnamlib.metadata_fields:
-                value1 = getattr(meta1, name)
-                value2 = getattr(meta2, name)
-                self.assertEqual(
-                    value1,
-                    value2,
-                    'attribute %s must be equal (%s vs %s)' %
-                        (name, value1, value2))
-
-    def test_round_trip(self):
-        metadata = obnamlib.Metadata(
-            st_mode=1,
-            st_mtime_sec=2,
-            st_mtime_nsec=12756,
-            st_nlink=3,
-            st_size=4,
-            st_uid=5,
-            st_blocks=6,
-            st_dev=7,
-            st_gid=8,
-            st_ino=9,
-            st_atime_sec=10,
-            st_atime_nsec=123,
-            groupname='group',
-            username='user',
-            target='target',
-            md5='checksum')
-        encoded = obnamlib.encode_metadata(metadata)
-        decoded = obnamlib.decode_metadata(encoded)
-        self.equal(metadata, decoded)
-
-    def test_round_trip_for_None_values(self):
-        metadata = obnamlib.Metadata()
-        encoded = obnamlib.encode_metadata(metadata)
-        decoded = obnamlib.decode_metadata(encoded)
-        for name in dir(metadata):
-            if name in obnamlib.metadata_fields:
-                self.assertEqual(getattr(decoded, name), None,
-                                 'attribute %s must be None' % name)
-
-    def test_round_trip_for_maximum_values(self):
-        unsigned_max = 2**64 - 1
-        signed_max = 2**63 - 1
-        metadata = obnamlib.Metadata(
-            st_mode=unsigned_max,
-            st_mtime_sec=signed_max,
-            st_mtime_nsec=unsigned_max,
-            st_nlink=unsigned_max,
-            st_size=signed_max,
-            st_uid=unsigned_max,
-            st_blocks=signed_max,
-            st_dev=unsigned_max,
-            st_gid=unsigned_max,
-            st_ino=unsigned_max,
-            st_atime_sec=signed_max,
-            st_atime_nsec=unsigned_max)
-        encoded = obnamlib.encode_metadata(metadata)
-        decoded = obnamlib.decode_metadata(encoded)
-        self.equal(metadata, decoded)
-
diff --git a/obnamlib/repo.py b/obnamlib/repo.py
index 12b6572b..f816e401 100644
--- a/obnamlib/repo.py
+++ b/obnamlib/repo.py
@@ -602,12 +602,12 @@ class Repository(object):
             encoded = self.client.get_metadata(gen, filename)
         except KeyError:
             raise obnamlib.Error('%s does not exist' % filename)
-        return obnamlib.decode_metadata(encoded)
+        return obnamlib.fmt_6.metadata_codec.decode_metadata(encoded)
 
     def create(self, filename, metadata):
         '''Create a new (empty) file in the new generation.'''
         self.require_started_generation()
-        encoded = obnamlib.encode_metadata(metadata)
+        encoded = obnamlib.fmt_6.metadata_codec.encode_metadata(metadata)
         self.client.create(filename, encoded)
 
     def remove(self, filename):