From aab83fa7a6bfb983b715acc4b01cb212b0dd4cf5 Mon Sep 17 00:00:00 2001
From: Herbert Valerio Riedel <hvr@gnu.org>
Date: Thu, 22 Sep 2016 08:31:02 +0200
Subject: [PATCH] Map chunked MD5s to md5zero

---
 src/Common.hs   | 2 ++
 src/SimpleS3.hs | 7 ++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/Common.hs b/src/Common.hs
index 0c660d1..4cb9007 100644
--- a/src/Common.hs
+++ b/src/Common.hs
@@ -3,6 +3,7 @@
 
 module Common
     ( module Common
+    , module Control.Applicative
     , module Data.Maybe
     , module Hackage.Security.Util.Path
     , module Data.Semigroup
@@ -16,6 +17,7 @@ module Common
     , NFData
     ) where
 
+import           Control.Applicative
 import           Control.DeepSeq
 import           Control.Exception
 import qualified Crypto.Hash.MD5            as MD5
diff --git a/src/SimpleS3.hs b/src/SimpleS3.hs
index 0451aa4..1412490 100644
--- a/src/SimpleS3.hs
+++ b/src/SimpleS3.hs
@@ -267,7 +267,12 @@ instance FromXML ObjMetaInfo where
         omiKey   <- (fromString . X.strContent) <$> X.findChild (s3qname "Key") el
         omiEtag_ <- X.strContent <$> X.findChild (s3qname "ETag") el
         omiMD5'  <- readMaybe omiEtag_
-        omiMD5   <- md5unhex omiMD5'
+        -- sometimes the reported MD5 is computed over chunks, in
+        -- which case the etag has a "-<num>" suffix. For now, we just
+        -- map those to the special zero MD5 as we can't do anything
+        -- sensible with it anyway (but we may want to be able to
+        -- detect that the MD5 reported was not a proper MD5)
+        omiMD5   <- md5unhex omiMD5' <|> Just md5zero
 
         omiSize_ <- X.strContent <$> X.findChild (s3qname "Size") el
         omiSize  <- readMaybe omiSize_