git-annex/Types/Backend.hs
2023-03-17 15:14:58 -04:00

44 lines
1.6 KiB
Haskell

{- git-annex key backend data type
-
- Most things should not need this, using Types instead
-
- Copyright 2010-2021 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Types.Backend where
import Types.Key
import Types.KeySource
import Utility.Metered
import Utility.FileSystemEncoding
import Utility.Hash (IncrementalVerifier)
data BackendA a = Backend
{ backendVariety :: KeyVariety
, genKey :: Maybe (KeySource -> MeterUpdate -> a Key)
-- Verifies the content of a key, stored in a file, using a hash.
-- This does not need to be cryptographically secure.
, verifyKeyContent :: Maybe (Key -> RawFilePath -> a Bool)
-- Incrementally verifies the content of a key, using the same
-- hash as verifyKeyContent, but with the content provided
-- incrementally a piece at a time, until finalized.
, verifyKeyContentIncrementally :: Maybe (Key -> a IncrementalVerifier)
-- Checks if a key can be upgraded to a better form.
, canUpgradeKey :: Maybe (Key -> Bool)
-- Checks if there is a fast way to migrate a key to a different
-- backend (ie, without re-hashing).
, fastMigrate :: Maybe (Key -> BackendA a -> AssociatedFile -> a (Maybe Key))
-- Checks if a key is known (or assumed) to always refer to the
-- same data.
, isStableKey :: Key -> Bool
-- Checks if a key is verified using a cryptographically secure hash.
, isCryptographicallySecure :: Key -> Bool
}
instance Show (BackendA a) where
show backend = "Backend { name =\"" ++ decodeBS (formatKeyVariety (backendVariety backend)) ++ "\" }"
instance Eq (BackendA a) where
a == b = backendVariety a == backendVariety b