From: kevan <kevan@isnotajoke.com>
Date: Sun, 25 Sep 2011 00:41:34 +0000 (-0700)
Subject: mutable/layout: break unpack_checkstring into unpack_mdmf_checkstring and unpack_sdmf... 
X-Git-Tag: allmydata-tahoe-1.9.0a2~8
X-Git-Url: https://git.rkrishnan.org/specifications/%5B/%5D%20/index.php?a=commitdiff_plain;h=e8afe848137d4c41bb7e9467b4d0b119dd2967e1;p=tahoe-lafs%2Ftahoe-lafs.git

mutable/layout: break unpack_checkstring into unpack_mdmf_checkstring and unpack_sdmf_checkstring, add distinguisher function for checkstrings
---

diff --git a/src/allmydata/mutable/layout.py b/src/allmydata/mutable/layout.py
index 55f39685..91486957 100644
--- a/src/allmydata/mutable/layout.py
+++ b/src/allmydata/mutable/layout.py
@@ -136,13 +136,24 @@ def unpack_share(data):
             pubkey, signature, share_hash_chain, block_hash_tree,
             share_data, enc_privkey)
 
-def unpack_checkstring(checkstring):
+def get_version_from_checkstring(checkstring):
+    (t, ) = struct.unpack(">B", checkstring[:1])
+    return t
+
+def unpack_sdmf_checkstring(checkstring):
     cs_len = struct.calcsize(PREFIX)
     version, seqnum, root_hash, IV = struct.unpack(PREFIX, checkstring[:cs_len])
     if version != 0: # TODO: just ignore the share
         raise UnknownVersionError("got mutable share version %d, but I only understand version 0" % version)
     return (seqnum, root_hash, IV)
 
+def unpack_mdmf_checkstring(checkstring):
+    cs_len = struct.calcsize(MDMFCHECKSTRING)
+    checkstring = checkstring[:cs_len]
+    version, seqnum, root_hash = struct.unpack(MDMFCHECKSTRING, checkstring)
+
+    assert version == 1
+    return (seqnum, root_hash)
 
 def pack_offsets(verification_key_length, signature_length,
                  share_hash_chain_length, block_hash_tree_length,