implement maxsize log and command

* maxsize: New command to tell git-annex how large the expected maximum
  size of a repository is.
* vicfg: Include maxsize configuration.

Logs/MaxSize.hs

@@ -0,0 +1,49 @@
+{- git-annex maxsize log
+ -
+ - Copyright 2024 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU AGPL version 3 or higher.
+ -}
+
+module Logs.MaxSize (
+	MaxSize(..),
+	getMaxSizes,
+	recordMaxSize,
+) where
+
+import qualified Annex
+import Annex.Common
+import Types.MaxSize
+import Logs
+import Logs.UUIDBased
+import Logs.MapLog
+import qualified Annex.Branch
+
+import qualified Data.Map as M
+import Data.ByteString.Builder
+import qualified Data.Attoparsec.ByteString as A
+
+getMaxSizes :: Annex (M.Map UUID MaxSize)
+getMaxSizes = maybe loadMaxSizes return =<< Annex.getState Annex.maxsizes
+
+loadMaxSizes :: Annex (M.Map UUID MaxSize)
+loadMaxSizes = do
+	maxsizes <- M.map value . fromMapLog . parseLogNew parseMaxSize
+		<$> Annex.Branch.get maxSizeLog
+	Annex.changeState $ \s -> s { Annex.maxsizes = Just maxsizes }
+	return maxsizes
+
+recordMaxSize :: UUID -> MaxSize -> Annex ()
+recordMaxSize uuid maxsize = do
+	c <- currentVectorClock
+	Annex.Branch.change (Annex.Branch.RegardingUUID [uuid]) maxSizeLog $
+		(buildLogNew buildMaxSize)
+			. changeLog c uuid maxsize
+			. parseLogNew parseMaxSize
+
+buildMaxSize :: MaxSize -> Builder
+buildMaxSize (MaxSize n) = byteString (encodeBS (show n))
+
+parseMaxSize :: A.Parser MaxSize
+parseMaxSize = maybe (fail "maxsize parse failed") (pure . MaxSize)
+	. readish . decodeBS =<< A.takeByteString