deal with unlocked files

P2P protocol version 1 adds VALID|INVALID after DATA; INVALID means the
file was detected to change content while it was being sent and so we
may not have received the valid content of the file.

Added new MustVerify constructor for Verification, which forces
verification even when annex.verify=false etc. This is used when INVALID
and in protocol version 0.

As well as changing git-annex-shell p2psdio, this makes git-annex tor
remotes always force verification, since they don't yet use protocol
version 1. Previously, annex.verify=false could skip verification when
using tor remotes, and let bad data into the repository.

This commit was sponsored by Jack Hill on Patreon.

Annex/Content.hs

@@ -16,7 +16,7 @@ module Annex.Content (
 	lockContentForRemoval,
 	ContentRemovalLock,
 	getViaTmp,
-	getViaTmp',
+	getViaTmpFromDisk,
 	checkDiskSpaceToGet,
 	prepTmp,
 	withTmp,
@@ -295,13 +295,13 @@ lockContentUsing locker key a = do
  - the key and moves the file into the annex as a key's content. -}
 getViaTmp :: VerifyConfig -> Key -> (FilePath -> Annex (Bool, Verification)) -> Annex Bool
 getViaTmp v key action = checkDiskSpaceToGet key False $
-	getViaTmp' v key action
+	getViaTmpFromDisk v key action
 
 {- Like getViaTmp, but does not check that there is enough disk space
  - for the incoming key. For use when the key content is already on disk
  - and not being copied into place. -}
-getViaTmp' :: VerifyConfig -> Key -> (FilePath -> Annex (Bool, Verification)) -> Annex Bool
-getViaTmp' v key action = do
+getViaTmpFromDisk :: VerifyConfig -> Key -> (FilePath -> Annex (Bool, Verification)) -> Annex Bool
+getViaTmpFromDisk v key action = do
 	tmpfile <- prepTmp key
 	(ok, verification) <- action tmpfile
 	if ok
@@ -331,12 +331,15 @@ getViaTmp' v key action = do
  - it is checked. 
  -}
 verifyKeyContent :: VerifyConfig -> Verification -> Key -> FilePath -> Annex Bool
-verifyKeyContent _ Verified _ _ = return True
-verifyKeyContent v UnVerified k f = ifM (shouldVerify v)
-	( verifysize <&&> verifycontent
-	, return True
-	)
+verifyKeyContent v verification k f = case verification of
+	Verified -> return True
+	UnVerified -> ifM (shouldVerify v)
+		( verify
+		, return True
+		)
+	MustVerify -> verify
   where
+	verify = verifysize <&&> verifycontent
 	verifysize = case keySize k of
 		Nothing -> return True
 		Just size -> do