addurl: --fast can be used to avoid immediately downloading the url.

The tricky part about this is that to generate a key, the file must be
present already. Worked around by adding (back) an URL key type, which
is used for addurl --fast.

Backend.hs

@@ -32,9 +32,10 @@ import Messages
 -- When adding a new backend, import it here and add it to the list.
 import qualified Backend.WORM
 import qualified Backend.SHA
+import qualified Backend.URL
 
 list :: [Backend Annex]
-list = Backend.WORM.backends ++ Backend.SHA.backends
+list = Backend.WORM.backends ++ Backend.SHA.backends ++ Backend.URL.backends
 
 {- List of backends in the order to try them when storing a new key. -}
 orderedList :: Annex [Backend Annex]

Backend/URL.hs

@@ -0,0 +1,28 @@
+{- git-annex "URL" backend -- keys whose content is available from urls.
+ -
+ - Copyright 2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Backend.URL (
+	backends,
+	fromUrl
+) where
+
+import Types.Backend
+import Types.Key
+import Types
+
+backends :: [Backend Annex]
+backends = [backend]
+
+backend :: Backend Annex
+backend = Types.Backend.Backend {
+	name = "URL",
+	getKey = const (return Nothing),
+	fsckKey = const (return True)
+}
+
+fromUrl :: String -> Key
+fromUrl url = stubKey { keyName = url, keyBackendName = "URL" }

Command/Add.hs

@@ -8,6 +8,7 @@
 module Command.Add where
 
 import Control.Monad.State (liftIO)
+import Control.Monad (when)
 import System.Posix.Files
 import System.Directory
 import Control.Exception.Control (handle)
@@ -52,7 +53,7 @@ perform (file, backend) = do
 		Nothing -> stop
 		Just (key, _) -> do
 			handle (undo file key) $ moveAnnex key file
-			next $ cleanup file key
+			next $ cleanup file key True
 
 {- On error, put the file back so it doesn't seem to have vanished.
  - This can be called before or after the symlink is in place. -}
@@ -72,11 +73,13 @@ undo file key e = do
 			g <- Annex.gitRepo
 			liftIO $ renameFile (gitAnnexLocation g key) file
 
-cleanup :: FilePath -> Key -> CommandCleanup
+cleanup :: FilePath -> Key -> Bool -> CommandCleanup
-cleanup file key = do
+cleanup file key hascontent = do
 	handle (undo file key) $ do
 		link <- calcGitLink file key
 		liftIO $ createSymbolicLink link file
+
+		when hascontent $ do
 			logStatus key InfoPresent
 	
 			-- touch the symlink to have the same mtime as the

Command/AddUrl.hs

@@ -17,10 +17,10 @@ import qualified Backend
 import qualified Remote.Web
 import qualified Command.Add
 import qualified Annex
+import qualified Backend.URL
 import Messages
 import Content
 import PresenceLog
-import Types.Key
 import Locations
 import Utility
 
@@ -42,9 +42,14 @@ start s = do
 			
 perform :: String -> FilePath -> CommandPerform
 perform url file = do
+	fast <- Annex.getState Annex.fast
+	if fast then nodownload url file else download url file
+
+download :: String -> FilePath -> CommandPerform
+download url file = do
 	g <- Annex.gitRepo
 	showAction $ "downloading " ++ url ++ " "
-	let dummykey = stubKey { keyName = url, keyBackendName = "URL" }
+	let dummykey = Backend.URL.fromUrl url
 	let tmp = gitAnnexTmpLocation g dummykey
 	liftIO $ createDirectoryIfMissing True (parentDir tmp)
 	ok <- Remote.Web.download [url] tmp
@@ -57,9 +62,16 @@ perform url file = do
 				Just (key, _) -> do
 					moveAnnex key tmp
 					Remote.Web.setUrl key url InfoPresent
-					next $ Command.Add.cleanup file key
+					next $ Command.Add.cleanup file key True
 		else stop
 
+nodownload :: String -> FilePath -> CommandPerform
+nodownload url file = do
+	let key = Backend.URL.fromUrl url
+	Remote.Web.setUrl key url InfoPresent
+	
+	next $ Command.Add.cleanup file key False
+
 url2file :: URI -> IO FilePath
 url2file url = do
 	let parts = filter safe $ split "/" $ uriPath url
@@ -75,8 +87,7 @@ url2file url = do
 			e <- doesFileExist file
 			when e $ error "already have this url"
 			return file
-		safe s
+		safe "" = False
-			| null s = False
+		safe "." = False
-			| s == "." = False
+		safe ".." = False
-			| s == ".." = False
+		safe _ = True
-			| otherwise = True

Command/Migrate.hs

@@ -72,7 +72,7 @@ perform file oldkey newbackend = do
 				then do
 					-- Update symlink to use the new key.
 					liftIO $ removeFile file
-					next $ Command.Add.cleanup file newkey
+					next $ Command.Add.cleanup file newkey True
 				else stop
 	where
 		cleantmp t = whenM (doesFileExist t) $ removeFile t

debian/changelog

@@ -1,6 +1,7 @@
 git-annex (3.20110720) UNRELEASED; urgency=low
 
   * Fix shell escaping in rsync special remote.
+  * addurl: --fast can be used to avoid immediately downloading the url.
 
  -- Joey Hess <joeyh@debian.org>  Fri, 29 Jul 2011 15:27:30 +0200
 

doc/git-annex.mdwn

@@ -282,6 +282,8 @@ Many git-annex commands will stage changes for later `git commit` by you.
 
   Downloads each url to a file, which is added to the annex.
 
+  To avoid immediately downloading the url, specify --fast
+
 * fromkey file
 
   This plumbing-level command can be used to manually set up a file