only enable SHA backends that configure finds support for

Backend.hs

@@ -26,7 +26,8 @@ module Backend (
 	fsckKey,
 	lookupFile,
 	chooseBackends,
-	keyBackend
+	keyBackend,
+	lookupBackendName
 ) where
 
 import Control.Monad.State

Backend/SHA.hs

@@ -5,13 +5,14 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-module Backend.SHA (genBackend) where
+module Backend.SHA (backends) where
 
 import Control.Monad.State
 import Data.String.Utils
 import System.Cmd.Utils
 import System.IO
 import System.Directory
+import Data.Maybe
 
 import qualified Backend.File
 import BackendTypes
@@ -21,16 +22,31 @@ import Locations
 import Content
 import Types
 import Utility
+import qualified SysConfig
 
 type SHASize = Int
 
--- Constructor for Backends using a given SHASize.
-genBackend :: SHASize -> Backend Annex
-genBackend size = Backend.File.backend 
-	{ name = shaName size
-	, getKey = keyValue size
-	, fsckKey = Backend.File.checkKey $ checkKeyChecksum size
-	}
+backends :: [Backend Annex]
+-- order is slightly significant; want sha1 first ,and more general
+-- sizes earlier
+backends = catMaybes $ map genBackend [1, 256, 512, 224, 384]
+
+genBackend :: SHASize -> Maybe (Backend Annex)
+genBackend size
+	| supported size = Just b 
+	| otherwise = Nothing
+	where
+		b = Backend.File.backend 
+			{ name = shaName size
+			, getKey = keyValue size
+			, fsckKey = Backend.File.checkKey $ checkKeyChecksum size
+			}
+		supported 1 = SysConfig.sha1sum
+		supported 256 = SysConfig.sha256sum
+		supported 224 = SysConfig.sha224sum
+		supported 384 = SysConfig.sha384sum
+		supported 512 = SysConfig.sha512sum
+		supported _ = False
 
 shaName :: SHASize -> String
 shaName size = "SHA" ++ show size

Backend/SHA1.hs

@@ -1,14 +0,0 @@
-{- git-annex "SHA1" backend
- -
- - Copyright 2011 Joey Hess <joey@kitenet.net>
- -
- - Licensed under the GNU GPL version 3 or higher.
- -}
-
-module Backend.SHA1 (backend) where
-
-import Types
-import Backend.SHA
-
-backend :: Backend Annex
-backend = genBackend 1

Backend/SHA224.hs

@@ -1,14 +0,0 @@
-{- git-annex "SHA224" backend
- -
- - Copyright 2011 Joey Hess <joey@kitenet.net>
- -
- - Licensed under the GNU GPL version 3 or higher.
- -}
-
-module Backend.SHA224 (backend) where
-
-import Types
-import Backend.SHA
-
-backend :: Backend Annex
-backend = genBackend 224

Backend/SHA384.hs

@@ -1,14 +0,0 @@
-{- git-annex "SHA384" backend
- -
- - Copyright 2011 Joey Hess <joey@kitenet.net>
- -
- - Licensed under the GNU GPL version 3 or higher.
- -}
-
-module Backend.SHA384 (backend) where
-
-import Types
-import Backend.SHA
-
-backend :: Backend Annex
-backend = genBackend 384

Backend/SHA512.hs

@@ -1,14 +0,0 @@
-{- git-annex "SHA512" backend
- -
- - Copyright 2011 Joey Hess <joey@kitenet.net>
- -
- - Licensed under the GNU GPL version 3 or higher.
- -}
-
-module Backend.SHA512 (backend) where
-
-import Types
-import Backend.SHA
-
-backend :: Backend Annex
-backend = genBackend 512

Backend/URL.hs

@@ -5,7 +5,7 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-module Backend.URL (backend) where
+module Backend.URL (backends) where
 
 import Control.Monad.State (liftIO)
 import Data.String.Utils
@@ -15,6 +15,9 @@ import BackendTypes
 import Utility
 import Messages
 
+backends :: [Backend Annex]
+backends = [backend]
+
 backend :: Backend Annex
 backend = Backend {
 	name = "URL",

Backend/WORM.hs

@@ -5,7 +5,7 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-module Backend.WORM (backend) where
+module Backend.WORM (backends) where
 
 import Control.Monad.State
 import System.FilePath
@@ -22,6 +22,9 @@ import Content
 import Messages
 import Types
 
+backends :: [Backend Annex]
+backends = [backend]
+
 backend :: Backend Annex
 backend = Backend.File.backend {
 	name = "WORM",

BackendList.hs

@@ -9,21 +9,13 @@ module BackendList (allBackends) where
 
 -- When adding a new backend, import it here and add it to the list.
 import qualified Backend.WORM
-import qualified Backend.SHA1
-import qualified Backend.SHA256
-import qualified Backend.SHA512
-import qualified Backend.SHA224
-import qualified Backend.SHA384
+import qualified Backend.SHA
 import qualified Backend.URL
 import Types
 
 allBackends :: [Backend Annex]
-allBackends = 
-	[ Backend.WORM.backend
-	, Backend.SHA1.backend
-	, Backend.SHA256.backend
-	, Backend.SHA512.backend
-	, Backend.SHA224.backend
-	, Backend.SHA384.backend
-	, Backend.URL.backend
+allBackends = concat 
+	[ Backend.WORM.backends
+	, Backend.SHA.backends
+	, Backend.URL.backends
 	]

doc/install.mdwn

@@ -16,7 +16,7 @@ To build and use git-annex, you will need:
   (or uuidgen from util-linux)
 * `xargs`: <http://savannah.gnu.org/projects/findutils/>
 * `rsync`: <http://rsync.samba.org/>
-* `sha1sum`: <ftp://ftp.gnu.org/gnu/coreutils/>
+* `sha1sum`: <ftp://ftp.gnu.org/gnu/coreutils/> (optional, but recommended)
 * Then just [[download]] git-annex and run: `make; make install`
 
 ([Ikiwiki](http://ikiwiki.info) is needed to build the documentation,

doc/install/OSX.mdwn

@@ -7,7 +7,7 @@ sudo port install pcre
 sudo cabal install pcre-light
 sudo cabal install quickcheck  
 
-# this will enable the gnu tools, (to give sha224sum etc..., it does not override the BSD userland)
+# optional: this will enable the gnu tools, (to give sha224sum etc..., it does not override the BSD userland)
 export PATH=$PATH:/opt/local/libexec/gnubin
 
 git clone  git://git.kitenet.net/git-annex

test.hs

@@ -37,8 +37,8 @@ import qualified UUID
 import qualified Trust
 import qualified Remotes
 import qualified Content
-import qualified Backend.SHA1
-import qualified Backend.WORM
+import qualified BackendList
+import qualified Backend
 import qualified Command.DropUnused
 
 main :: IO ()
@@ -121,7 +121,7 @@ test_add = "git-annex add" ~: TestList [basic, sha1dup]
 test_setkey :: Test
 test_setkey = "git-annex setkey/fromkey" ~: TestCase $ inmainrepo $ do
 	writeFile tmp $ content sha1annexedfile
-	r <- annexeval $ BackendTypes.getKey Backend.SHA1.backend tmp
+	r <- annexeval $ BackendTypes.getKey backendSHA1 tmp
 	let sha1 = BackendTypes.keyName $ fromJust r
 	git_annex "setkey" ["-q", "--backend", "SHA1", "--key", sha1, tmp] @? "setkey failed"
 	git_annex "fromkey" ["-q", "--backend", "SHA1", "--key", sha1, sha1annexedfile] @? "fromkey failed"
@@ -405,8 +405,8 @@ test_migrate = "git-annex migrate" ~: TestList [t False, t True]
 					@? "migrate annexedfile failed"
 		annexed_present annexedfile
 		annexed_present sha1annexedfile
-		checkbackend annexedfile Backend.SHA1.backend
-		checkbackend sha1annexedfile Backend.SHA1.backend
+		checkbackend annexedfile backendSHA1
+		checkbackend sha1annexedfile backendSHA1
 
 		-- check that reversing a migration works
 		writeFile ".gitattributes" $ "* annex.backend=WORM"
@@ -416,8 +416,8 @@ test_migrate = "git-annex migrate" ~: TestList [t False, t True]
 			@? "migrate annexedfile failed"
 		annexed_present annexedfile
 		annexed_present sha1annexedfile
-		checkbackend annexedfile Backend.WORM.backend
-		checkbackend sha1annexedfile Backend.WORM.backend
+		checkbackend annexedfile backendWORM
+		checkbackend sha1annexedfile backendWORM
 		
 		where
 			checkbackend file expected = do
@@ -682,3 +682,12 @@ changecontent f = writeFile f $ changedcontent f
 
 changedcontent :: FilePath -> String
 changedcontent f = (content f) ++ " (modified)"
+
+backendSHA1 :: Types.Backend Types.Annex
+backendSHA1 = backend_ "SHA1"
+
+backendWORM :: Types.Backend Types.Annex
+backendWORM = backend_ "WORM"
+
+backend_ :: String -> Types.Backend Types.Annex
+backend_ name = Backend.lookupBackendName BackendList.allBackends name