move verifyKeyContent to Annex.Verify

The goal is that Database.Keys be able to use it; it can't use
Annex.Content.Presence due to an import loop.

Several other things also needed to be moved to Annex.Verify as a
conseqence.

Annex/Content.hs

@@ -66,6 +66,7 @@ import Annex.Common
 import Annex.Content.Presence
 import Annex.Content.LowLevel
 import Annex.Content.PointerFile
+import Annex.Verify
 import qualified Git
 import qualified Annex
 import qualified Annex.Queue
@@ -253,7 +254,7 @@ getViaTmpFromDisk rsp v key af action = checkallowed $ do
 	-- RetrievalSecurityPolicy would cause verification to always fail.
 	checkallowed a = case rsp of
 		RetrievalAllKeysSecure -> a
-		RetrievalVerifiableKeysSecure -> ifM (Backend.isVerifiable key)
+		RetrievalVerifiableKeysSecure -> ifM (isVerifiable key)
 			( a
 			, ifM (annexAllowUnverifiedDownloads <$> Annex.getGitConfig)
 				( a

Annex/Content/Presence.hs

@@ -17,11 +17,6 @@ module Annex.Content.Presence (
 	isUnmodified,
 	isUnmodified',
 	isUnmodifiedCheap,
-	verifyKeyContent,
-	VerifyConfig(..),
-	Verification(..),
-	unVerified,
-	warnUnverifiableInsecure,
 	contentLockFile,
 ) where
 
@@ -29,15 +24,10 @@ import Annex.Common
 import qualified Annex
 import Annex.Verify
 import Annex.LockPool
-import Annex.WorkerPool
-import Types.Remote (unVerified, Verification(..), RetrievalSecurityPolicy(..))
-import qualified Types.Backend
-import qualified Backend
 import qualified Database.Keys
-import Types.Key
+import Types.Remote
 import Annex.InodeSentinal
 import Utility.InodeCache
-import Types.WorkerPool
 import qualified Utility.RawFilePath as R
 
 #ifdef mingw32_HOST_OS
@@ -189,55 +179,3 @@ isUnmodifiedCheap' key fc = isUnmodifiedCheap'' fc
 
 isUnmodifiedCheap'' :: InodeCache -> [InodeCache] -> Annex Bool
 isUnmodifiedCheap'' fc ic = anyM (compareInodeCaches fc) ic
-
-{- Verifies that a file is the expected content of a key.
- -
- - Configuration can prevent verification, for either a
- - particular remote or always, unless the RetrievalSecurityPolicy
- - requires verification.
- -
- - Most keys have a known size, and if so, the file size is checked.
- -
- - When the key's backend allows verifying the content (via checksum),
- - it is checked. 
- -
- - If the RetrievalSecurityPolicy requires verification and the key's
- - backend doesn't support it, the verification will fail.
- -}
-verifyKeyContent :: RetrievalSecurityPolicy -> VerifyConfig -> Verification -> Key -> RawFilePath -> Annex Bool
-verifyKeyContent rsp v verification k f = case (rsp, verification) of
-	(_, Verified) -> return True
-	(RetrievalVerifiableKeysSecure, _) -> ifM (Backend.isVerifiable k)
-		( verify
-		, ifM (annexAllowUnverifiedDownloads <$> Annex.getGitConfig)
-			( verify
-			, warnUnverifiableInsecure k >> return False
-			)
-		)
-	(_, UnVerified) -> ifM (shouldVerify v)
-		( verify
-		, return True
-		)
-	(_, MustVerify) -> verify
-  where
-	verify = enteringStage VerifyStage $ verifysize <&&> verifycontent
-	verifysize = case fromKey keySize k of
-		Nothing -> return True
-		Just size -> do
-			size' <- liftIO $ catchDefaultIO 0 $ getFileSize f
-			return (size' == size)
-	verifycontent = Backend.maybeLookupBackendVariety (fromKey keyVariety k) >>= \case
-		Nothing -> return True
-		Just b -> case Types.Backend.verifyKeyContent b of
-			Nothing -> return True
-			Just verifier -> verifier k f
-
-warnUnverifiableInsecure :: Key -> Annex ()
-warnUnverifiableInsecure k = warning $ unwords
-	[ "Getting " ++ kv ++ " keys with this remote is not secure;"
-	, "the content cannot be verified to be correct."
-	, "(Use annex.security.allow-unverified-downloads to bypass"
-	, "this safety check.)"
-	]
-  where
-	kv = decodeBS (formatKeyVariety (fromKey keyVariety k))

Annex/CopyFile.hs

@@ -16,7 +16,6 @@ import Utility.CopyFile
 import Utility.FileMode
 import Utility.Touch
 import Types.Backend
-import Backend
 import Annex.Verify
 
 import Control.Concurrent

Annex/Verify.hs

@@ -5,11 +5,28 @@
  - Licensed under the GNU AGPL version 3 or higher.
  -}
 
-module Annex.Verify where
+module Annex.Verify (
+	VerifyConfig(..),
+	shouldVerify,
+	verifyKeyContent,
+	Verification(..),
+	unVerified,
+	warnUnverifiableInsecure,
+	isVerifiable,
+	startVerifyKeyContentIncrementally,
+	IncrementalVerifier(..),
+) where
 
 import Annex.Common
 import qualified Annex
 import qualified Types.Remote
+import qualified Types.Backend
+import Types.Backend (IncrementalVerifier(..))
+import qualified Backend
+import Types.Remote (unVerified, Verification(..), RetrievalSecurityPolicy(..))
+import Annex.WorkerPool
+import Types.WorkerPool
+import Types.Key
 
 data VerifyConfig = AlwaysVerify | NoVerify | RemoteVerify Remote | DefaultVerify
 
@@ -23,3 +40,70 @@ shouldVerify (RemoteVerify r) =
 	-- Export remotes are not key/value stores, so always verify
 	-- content from them even when verification is disabled.
 	<||> Types.Remote.isExportSupported r
+
+{- Verifies that a file is the expected content of a key.
+ -
+ - Configuration can prevent verification, for either a
+ - particular remote or always, unless the RetrievalSecurityPolicy
+ - requires verification.
+ -
+ - Most keys have a known size, and if so, the file size is checked.
+ -
+ - When the key's backend allows verifying the content (via checksum),
+ - it is checked. 
+ -
+ - If the RetrievalSecurityPolicy requires verification and the key's
+ - backend doesn't support it, the verification will fail.
+ -}
+verifyKeyContent :: RetrievalSecurityPolicy -> VerifyConfig -> Verification -> Key -> RawFilePath -> Annex Bool
+verifyKeyContent rsp v verification k f = case (rsp, verification) of
+	(_, Verified) -> return True
+	(RetrievalVerifiableKeysSecure, _) -> ifM (isVerifiable k)
+		( verify
+		, ifM (annexAllowUnverifiedDownloads <$> Annex.getGitConfig)
+			( verify
+			, warnUnverifiableInsecure k >> return False
+			)
+		)
+	(_, UnVerified) -> ifM (shouldVerify v)
+		( verify
+		, return True
+		)
+	(_, MustVerify) -> verify
+  where
+	verify = enteringStage VerifyStage $ verifysize <&&> verifycontent
+	verifysize = case fromKey keySize k of
+		Nothing -> return True
+		Just size -> do
+			size' <- liftIO $ catchDefaultIO 0 $ getFileSize f
+			return (size' == size)
+	verifycontent = Backend.maybeLookupBackendVariety (fromKey keyVariety k) >>= \case
+		Nothing -> return True
+		Just b -> case Types.Backend.verifyKeyContent b of
+			Nothing -> return True
+			Just verifier -> verifier k f
+
+warnUnverifiableInsecure :: Key -> Annex ()
+warnUnverifiableInsecure k = warning $ unwords
+	[ "Getting " ++ kv ++ " keys with this remote is not secure;"
+	, "the content cannot be verified to be correct."
+	, "(Use annex.security.allow-unverified-downloads to bypass"
+	, "this safety check.)"
+	]
+  where
+	kv = decodeBS (formatKeyVariety (fromKey keyVariety k))
+
+isVerifiable :: Key -> Annex Bool
+isVerifiable k = maybe False (isJust . Types.Backend.verifyKeyContent) 
+	<$> Backend.maybeLookupBackendVariety (fromKey keyVariety k)
+
+startVerifyKeyContentIncrementally :: VerifyConfig -> Key -> Annex (Maybe IncrementalVerifier)
+startVerifyKeyContentIncrementally verifyconfig k = 
+	ifM (shouldVerify verifyconfig)
+		( Backend.maybeLookupBackendVariety (fromKey keyVariety k) >>= \case
+			Just b -> case Types.Backend.verifyKeyContentIncrementally b of
+				Just v -> Just <$> v k
+				Nothing -> return Nothing
+			Nothing -> return Nothing
+		, return Nothing
+		)

Backend.hs

@@ -16,14 +16,11 @@ module Backend (
 	maybeLookupBackendVariety,
 	isStableKey,
 	isCryptographicallySecure,
-	isVerifiable,
-	startVerifyKeyContentIncrementally,
 ) where
 
 import Annex.Common
 import qualified Annex
 import Annex.CheckAttr
-import Annex.Verify
 import Types.Key
 import Types.KeySource
 import qualified Types.Backend as B
@@ -125,18 +122,3 @@ isStableKey k = maybe False (`B.isStableKey` k)
 isCryptographicallySecure :: Key -> Annex Bool
 isCryptographicallySecure k = maybe False (`B.isCryptographicallySecure` k)
 	<$> maybeLookupBackendVariety (fromKey keyVariety k)
-
-isVerifiable :: Key -> Annex Bool
-isVerifiable k = maybe False (isJust . B.verifyKeyContent) 
-	<$> maybeLookupBackendVariety (fromKey keyVariety k)
-
-startVerifyKeyContentIncrementally :: VerifyConfig -> Key -> Annex (Maybe B.IncrementalVerifier)
-startVerifyKeyContentIncrementally verifyconfig k = 
-	ifM (shouldVerify verifyconfig)
-		( maybeLookupBackendVariety (fromKey keyVariety k) >>= \case
-			Just b -> case B.verifyKeyContentIncrementally b of
-				Just v -> Just <$> v k
-				Nothing -> return Nothing
-			Nothing -> return Nothing
-		, return Nothing
-		)

P2P/Annex.hs

@@ -23,8 +23,7 @@ import P2P.IO
 import Logs.Location
 import Types.NumCopies
 import Utility.Metered
-import Types.Backend (IncrementalVerifier(..))
+import Annex.Verify
-import Backend
 
 import Control.Monad.Free
 import Control.Concurrent.STM

Remote/Helper/ExportImport.hs

@@ -13,7 +13,7 @@ import Annex.Common
 import Types.Remote
 import Types.Key
 import Types.ProposedAccepted
-import Backend
+import Annex.Verify
 import Remote.Helper.Encryptable (encryptionIsEnabled)
 import qualified Database.Export as Export
 import qualified Database.ContentIdentifier as ContentIdentifier

Remote/Helper/P2P.hs

@@ -17,7 +17,7 @@ import Annex.Content
 import Messages.Progress
 import Utility.Metered
 import Types.NumCopies
-import Backend
+import Annex.Verify
 
 import Control.Concurrent