calckey: New plumbing command, calculates the key that would be used to refer to a file

CmdLine/GitAnnex.hs

@@ -25,6 +25,7 @@ import qualified Command.Copy
 import qualified Command.Get
 import qualified Command.Fsck
 import qualified Command.LookupKey
+import qualified Command.CalcKey
 import qualified Command.ContentLocation
 import qualified Command.ExamineKey
 import qualified Command.MatchExpression
@@ -162,6 +163,7 @@ cmds testoptparser testrunner =
 	, Command.Ungroup.cmd
 	, Command.Vicfg.cmd
 	, Command.LookupKey.cmd
+	, Command.CalcKey.cmd
 	, Command.ContentLocation.cmd
 	, Command.ExamineKey.cmd
 	, Command.MatchExpression.cmd

Command/CalcKey.hs

@@ -0,0 +1,28 @@
+{- git-annex command
+ -
+ - Copyright 2016 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Command.CalcKey where
+
+import Command
+import Backend (genKey)
+import Types.KeySource
+
+cmd :: Command
+cmd = noCommit $ noMessages $ dontCheck repoExists $
+	command "calckey" SectionPlumbing 
+		"calculates the key that would be used to refer to a file"
+		(paramRepeating paramFile)
+		(batchable run (pure ()))
+
+run :: () -> String -> Annex Bool
+run _ file = do
+	mkb <- genKey (KeySource file file Nothing) Nothing
+	case mkb of
+		Just (k, _) -> do
+			liftIO $ putStrLn $ key2file k
+			return True
+		Nothing -> return False

debian/changelog

@@ -6,6 +6,8 @@ git-annex (6.20160419) UNRELEASED; urgency=medium
     fixed to not hang when it cannot find locale files.
   * reinject: When src file's content cannot be verified, leave it alone,
     instead of deleting it.
+  * calckey: New plumbing command, calculates the key that would be used
+    to refer to a file.
 
  -- Joey Hess <id@joeyh.name>  Tue, 19 Apr 2016 12:57:15 -0400
 

doc/git-annex-calckey.mdwn

@@ -0,0 +1,35 @@
+# NAME
+
+git-annex calckey - calculates the key that would be used to refer to a file
+
+# SYNOPSIS
+
+git annex calckey `[file ...]`
+
+# DESCRIPTION
+
+This plumbing-level command calculates the key that would be used
+to refer to a file. The file is not added to the annex by this command.
+The key is output to stdout.
+
+The backend used is the first listed in the annex.backends configuration
+setting. For example, to force use of the SHA1 backend:
+
+	git annex calckey -c annex.backends=SHA1 file
+
+# OPTIONS
+
+* `--batch`
+
+  Enable batch mode, in which a line containing the filename is read from
+  stdin, the key is output to stdout (with a trailing newline), and repeat.
+
+# SEE ALSO
+
+[[git-annex]](1)
+
+# AUTHOR
+
+Joey Hess <id@joeyh.name>
+
+Warning: Automatically converted into a man page by mdwn2man. Edit with care.

doc/git-annex.mdwn

@@ -530,6 +530,12 @@ subdirectories).
 
   See [[git-annex-lookupkey]](1) for details.
 
+* `calckey [file ...]`
+
+  Calculates the key that would be used to refer to a file.
+  
+  See [[git-annex-calckey]](1) for details.
+
 * `contentlocation [key ..]`
 
   Looks up location of annexed content for a key.

doc/todo/import_--reinject/comment_4_2ff1a97aea8c0a565a23d5f007e4490c._comment

@@ -0,0 +1,31 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 4"""
+ date="2016-04-20T17:22:06Z"
+ content="""
+I think this would fit better as an option to `git annex reinject` than
+it would to `git annex import`. The latter has too many options anyway.
+
+It would not be hard to add something like `git annex reinject
+--all-known-files`, which would check if a source file hashes to a known
+key and ingest its content into the annex if so, otherwise leaving the
+source file along.
+
+That would reinject files that had been added to the repo long ago, and
+then were deleted. I don't know if that would be considered suprising
+behavior, but it's hard to only ingest files that have a current link in
+the repo (because a. git-annex keeps no such index (mostly) and b. branches and c.
+tags). Even if it was surprising behavior to reinject old deleted files,
+I suppose `git annex unused` could be used to drop such old unused file
+contents after reinjecting them.
+
+There's also the problem of different backends; it seems such a thing would
+need to hash a file 5 different ways to make sure no hash of it is known.
+
+As to adding plumbing, I'm always open to ideas for more useful plumbing.
+
+* You can use `git annex find` to get eg, a list of keys of files in the
+  currently checked out branch. 
+* I've added a `git annex calckey` that can calculate the key that would be
+  used for a file. (eg, hashing it)
+"""]]