require "annex/objects/" before key in pointer files

This removes ambiguity, because while someone might have "WORM--foo" in a
file that's not intended to be a git-annex pointer file,
"annex/objects/WORM--foo" is less likely.

Also, 664cc987e8 had a caveat about symlink
targets being parsed as pointer files, and now the same parser is used for
both.

I did not include any hash directories before the key in the pointer file,
as they're not needed. However, if they were included, the parser would
still work ok.

Annex/CatFile.hs

@@ -83,16 +83,8 @@ catFileStop = do
 
 {- From ref to a symlink or a pointer file, get the key. -}
 catKey :: Ref -> Annex (Maybe Key)
-catKey ref = do
-	o <- catObject ref
-	if L.length o > maxsz
-		then return Nothing -- too big
-		else do
-			let l = decodeBS o
-			let l' = fromInternalGitPath l
-			return $ if isLinkToAnnex l'
-				then fileKey $ takeFileName l'
-				else parsePointer l
+catKey ref = parsePointer . fromInternalGitPath . decodeBS . L.take maxsz 
+	<$> catObject ref
   where
 	-- Want to avoid buffering really big files in git into memory.
 	-- 8192 bytes is plenty for a pointer to a key.
@@ -102,7 +94,11 @@ catKey ref = do
 
 {- Only look at the first line of a pointer file. -}
 parsePointer :: String -> Maybe Key
-parsePointer s = headMaybe (lines s) >>= file2key
+parsePointer s = headMaybe (lines s) >>= go
+  where
+	go l
+		| isLinkToAnnex l = file2key $ takeFileName l
+		| otherwise = Nothing
 
 {- Gets a symlink target. -}
 catSymLinkTarget :: Sha -> Annex String

Command/Smudge.hs

@@ -18,6 +18,7 @@ import Types.KeySource
 import Backend
 import Logs.Location
 import qualified Database.AssociatedFiles as AssociatedFiles
+import Git.FilePath
 
 import qualified Data.ByteString.Lazy as B
 
@@ -104,7 +105,8 @@ ingest file = do
 -- Could add a newline and some text explaining this file is a pointer.
 -- parsePointer only looks at the first line.
 emitPointer :: Key -> IO ()
-emitPointer = putStrLn . key2file
+emitPointer k = putStrLn $ toInternalGitPath $
+	pathSeparator:objectDir </> key2file k
 
 updateAssociatedFiles :: Key -> FilePath -> Annex ()
 updateAssociatedFiles k f = do

doc/todo/smudge.mdwn

@@ -158,7 +158,8 @@ Using git-annex on a crippled filesystem that does not support symlinks.
 Data:
 
 * An annex pointer file has as its first line the git-annex key
-  that it's standing in for. Subsequent lines of the file might
+  that it's standing in for (prefixed with "annex/objects/", similar to
+  an annex symlink target). Subsequent lines of the file might
   be a message saying that the file's content is not currently available.
   An annex pointer file is checked into the git repository the same way
   that an annex symlink is checked in.