lookupkey: Added --ref option

Sponsored-by: Joshua Antonishen on Patreon

CHANGELOG

@@ -11,6 +11,7 @@ git-annex (10.20230829) UNRELEASED; urgency=medium
     filenames that confuse adb shell commands.
   * push: When on an adjusted branch, propagate changes to parent branch
     before updating export remotes.
+  * lookupkey: Added --ref option.
 
  -- Joey Hess <id@joeyh.name>  Mon, 28 Aug 2023 13:10:17 -0400
 

Command/LookupKey.hs

@@ -10,6 +10,7 @@ module Command.LookupKey where
 import Command
 import Annex.CatFile
 import qualified Git.LsFiles
+import Git.Types
 import Utility.Terminal
 import Utility.SafeOutput
 
@@ -18,18 +19,33 @@ cmd = notBareRepo $ noCommit $ noMessages $
 	command "lookupkey" SectionPlumbing 
 		"looks up key used for file"
 		(paramRepeating paramFile)
-		(batchable run (pure ()))
+		(batchable run optParser)
 
-run :: () -> SeekInput -> String -> Annex Bool
-run _ _ file = seekSingleGitFile file >>= \case
-	Nothing -> return False
-	Just file' -> catKeyFile file' >>= \case
-		Just k  -> do
-			IsTerminal isterminal <- liftIO $ checkIsTerminal stdout
-			let sk = serializeKey k
-			liftIO $ putStrLn $ if isterminal then safeOutput sk else sk
-			return True
+data LookupKeyOptions = LookupKeyOptions
+	{ refOption :: Bool
+	}
+
+optParser :: Parser LookupKeyOptions
+optParser = LookupKeyOptions
+	<$> switch
+		( long "ref"
+		<> help "look up key used by git ref to file"
+		)
+
+run :: LookupKeyOptions -> SeekInput -> String -> Annex Bool
+run o _ file
+	| refOption o = catKey (Ref (toRawFilePath file)) >>= display
+	| otherwise = seekSingleGitFile file >>= \case
 		Nothing -> return False
+		Just file' -> catKeyFile file' >>= display
+
+display :: Maybe Key -> Annex Bool
+display (Just k) = do
+	IsTerminal isterminal <- liftIO $ checkIsTerminal stdout
+	let sk = serializeKey k
+	liftIO $ putStrLn $ if isterminal then safeOutput sk else sk
+	return True
+display Nothing = return False
 
 -- To support absolute filenames, pass through git ls-files.
 -- But, this plumbing command does not recurse through directories.

doc/git-annex-get/comment_2_ce5c85afa01019afe58c79df151c65ff._comment

@@ -0,0 +1,12 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""Re: get file by branch and path in bare repository"""
+ date="2023-09-12T16:46:55Z"
+ content="""
+--branch is limited to a treeish, so not a single file.
+
+You can use `git-annex lookupkey --ref` to look up the key used by a ref to
+a file, and then pass that to `git-annex get --key`
+
+(That's a new feature I added due to you asking this question.)
+"""]]

doc/git-annex-lookupkey.mdwn

@@ -15,6 +15,13 @@ nothing is output, and it exits nonzero.
 
 # OPTIONS
 
+* `--ref`
+
+  Rather than looking for the specified files in the index, interpet them
+  as git refs. For example to find the key used for somefile in tag v1.0:
+
+    git-annex lookupkey v1.0:somefile
+
 * `--batch`
 
   Enable batch mode, in which a line containing the filename is read from