execute remote.<name>.annex-shell on remote, if set

It is useful to be able to specify an alternative git-annex-shell
program to execute on the remote, e.g., to run a version not on the
PATH.  Use remote.<name>.annex-shell if specified, instead of the
default "git-annex-shell" i.e., first so-named executable on the
PATH.

Command/Map.hs

@@ -22,6 +22,7 @@ import Logs.UUID
 import Logs.Trust
 import qualified Remote.Helper.Ssh as Ssh
 import qualified Utility.Dot as Dot
+import Types.GitConfig
 
 -- a link from the first repository to the second (its remote)
 data Link = Link Git.Repo Git.Repo
@@ -203,7 +204,9 @@ tryScan r
 
 	configlist = Ssh.onRemote r (pipedconfig, Nothing) "configlist" [] []
 	manualconfiglist = do
-		sshparams <- Ssh.toRepo r [Param sshcmd]
+		g <- fromRepo id
+		let c = extractRemoteGitConfig g (Git.repoDescribe r)
+		sshparams <- Ssh.toRepo r c [Param sshcmd]
 		liftIO $ pipedconfig "ssh" sshparams
 	  where
 		sshcmd = cddir ++ " && " ++

Remote/Bup.hs

@@ -13,6 +13,7 @@ import System.Process
 import Data.ByteString.Lazy.UTF8 (fromString)
 
 import Common.Annex
+import Types.GitConfig
 import Types.Remote
 import Types.Key
 import Types.Creds
@@ -223,7 +224,9 @@ storeBupUUID u buprepo = do
 
 onBupRemote :: Git.Repo -> (FilePath -> [CommandParam] -> IO a) -> FilePath -> [CommandParam] -> Annex a
 onBupRemote r a command params = do
-	sshparams <- Ssh.toRepo r [Param $
+	g <- fromRepo id
+	let c = extractRemoteGitConfig g (Git.repoDescribe r)
+	sshparams <- Ssh.toRepo r c [Param $
 			"cd " ++ dir ++ " && " ++ unwords (command : toCommand params)]
 	liftIO $ a "ssh" sshparams
   where

Remote/Helper/Ssh.hs

@@ -26,10 +26,8 @@ import Config
 {- Generates parameters to ssh to a repository's host and run a command.
  - Caller is responsible for doing any neccessary shellEscaping of the
  - passed command. -}
-toRepo :: Git.Repo -> [CommandParam] -> Annex [CommandParam]
+toRepo :: Git.Repo -> RemoteGitConfig -> [CommandParam] -> Annex [CommandParam]
-toRepo r sshcmd = do
+toRepo r c sshcmd = do
-	g <- fromRepo id
-	let c = extractRemoteGitConfig g (Git.repoDescribe r)
 	let opts = map Param $ remoteAnnexSshOptions c
 	let host = fromMaybe (error "bad ssh url") $ Git.Url.hostuser r
 	params <- sshCachingOptions (host, Git.Url.port r) opts
@@ -41,16 +39,19 @@ git_annex_shell :: Git.Repo -> String -> [CommandParam] -> [(Field, String)] ->
 git_annex_shell r command params fields
 	| not $ Git.repoIsUrl r = return $ Just (shellcmd, shellopts ++ fieldopts)
 	| Git.repoIsSsh r = do
+		g <- fromRepo id
+		let c = extractRemoteGitConfig g (Git.repoDescribe r)
 		u <- getRepoUUID r
-		sshparams <- toRepo r [Param $ sshcmd u ]
+		sshparams <- toRepo r c [Param $ sshcmd u c]
 		return $ Just ("ssh", sshparams)
 	| otherwise = return Nothing
   where
 	dir = Git.repoPath r
 	shellcmd = "git-annex-shell"
 	shellopts = Param command : File dir : params
-	sshcmd u = unwords $
+	sshcmd u c = unwords $
-		shellcmd : map shellEscape (toCommand shellopts) ++
+		fromMaybe shellcmd (remoteAnnexShell c)
+			: map shellEscape (toCommand shellopts) ++
 		uuidcheck u ++
 		map shellEscape (toCommand fieldopts)
 	uuidcheck NoUUID = []

Types/GitConfig.hs

@@ -119,6 +119,7 @@ data RemoteGitConfig = RemoteGitConfig
 
 	{- These settings are specific to particular types of remotes
 	 - including special remotes. -}
+	, remoteAnnexShell :: Maybe String
 	, remoteAnnexSshOptions :: [String]
 	, remoteAnnexRsyncOptions :: [String]
 	, remoteAnnexRsyncUploadOptions :: [String]
@@ -151,6 +152,7 @@ extractRemoteGitConfig r remotename = RemoteGitConfig
 	, remoteAnnexAvailability = getmayberead "availability"
 	, remoteAnnexBare = getmaybebool "bare"
 
+	, remoteAnnexShell = getmaybe "shell"
 	, remoteAnnexSshOptions = getoptions "ssh-options"
 	, remoteAnnexRsyncOptions = getoptions "rsync-options"
 	, remoteAnnexRsyncDownloadOptions = getoptions "rsync-download-options"

doc/git-annex.mdwn

@@ -1493,6 +1493,14 @@ Here are all the supported configuration settings.
   The command will only be run once *all* running git-annex processes
   are finished using the remote.
 
+* `remote.<name>.annex-shell`
+
+  Specify an alternative git-annex-shell executable on the remote
+  instead of looking for "git-annex-shell" on the PATH.
+
+  This is useful if the git-annex-shell program is outside the PATH
+  or has a non-standard name.
+
 * `remote.<name>.annex-ignore`
 
   If set to `true`, prevents git-annex