prevent numcopies or mincopies being configured to 0

Ignore annex.numcopies set to 0 in gitattributes or git config, or by
git-annex numcopies or by --numcopies, since that configuration would make
git-annex easily lose data. Same for mincopies.

This is a continuation of the work to make data only be able to be lost
when --force is used. It earlier led to the --trust option being disabled,
and similar reasoning applies here.

Most numcopies configs had docs that strongly discouraged setting it to 0
anyway. And I can't imagine a use case for setting to 0. Not that there
might not be one, but it's just so far from the intended use case of
git-annex, of managing and storing your data, that it does not seem like
it makes sense to cater to such a hypothetical use case, where any
git-annex drop can lose your data at any time.

Using a smart constructor makes sure every place avoids 0. Note that this
does mean that NumCopies is for the configured desired values, and not the
actual existing number of copies, which of course can be 0. The name
configuredNumCopies is used to make that clear.

Sponsored-by: Brock Spratlen on Patreon

Command/Drop.hs

@@ -252,7 +252,7 @@ checkDropAuto automode mremote afile key a =
 			uuid <- getUUID
 			let remoteuuid = fromMaybe uuid $ Remote.uuid <$> mremote
 			locs' <- trustExclude UnTrusted $ filter (/= remoteuuid) locs
-			if NumCopies (length locs') >= numcopies
+			if length locs' >= fromNumCopies numcopies
 				then a numcopies mincopies
 				else stop
 		| otherwise = a numcopies mincopies

Command/Fsck.hs

@@ -517,8 +517,8 @@ checkKeyNumCopies key afile numcopies = do
 	locs <- loggedLocations key
 	(untrustedlocations, otherlocations) <- trustPartition UnTrusted locs
 	(deadlocations, safelocations) <- trustPartition DeadTrusted otherlocations
-	let present = NumCopies (length safelocations)
-	if present < numcopies
+	let present = length safelocations
+	if present < fromNumCopies numcopies
 		then ifM (pure (not hasafile) <&&> checkDead key)
 			( do
 				showLongNote $ "This key is dead, skipping."
@@ -527,21 +527,21 @@ checkKeyNumCopies key afile numcopies = do
 				untrusted <- Remote.prettyPrintUUIDs "untrusted" untrustedlocations
 				dead <- Remote.prettyPrintUUIDs "dead" deadlocations
 				warning $ missingNote desc present numcopies untrusted dead
-				when (fromNumCopies present == 0 && not hasafile) $
+				when (present == 0 && not hasafile) $
 					showLongNote "(Avoid this check by running: git annex dead --key )"
 				return False
 			)
 		else return True
 
-missingNote :: String -> NumCopies -> NumCopies -> String -> String -> String
-missingNote file (NumCopies 0) _ [] dead = 
+missingNote :: String -> Int -> NumCopies -> String -> String -> String
+missingNote file 0 _ [] dead = 
 		"** No known copies exist of " ++ file ++ honorDead dead
-missingNote file (NumCopies 0) _ untrusted dead =
+missingNote file 0 _ untrusted dead =
 		"Only these untrusted locations may have copies of " ++ file ++
 		"\n" ++ untrusted ++
 		"Back it up to trusted locations with git-annex copy." ++ honorDead dead
 missingNote file present needed [] _ =
-		"Only " ++ show (fromNumCopies present) ++ " of " ++ show (fromNumCopies needed) ++ 
+		"Only " ++ show present ++ " of " ++ show (fromNumCopies needed) ++ 
 		" trustworthy copies exist of " ++ file ++
 		"\nBack it up with git-annex copy."
 missingNote file present needed untrusted dead = 

Command/MinCopies.hs

@@ -32,7 +32,7 @@ startGet = startingCustomOutput (ActionItemOther Nothing) $ next $ do
 
 startSet :: Int -> CommandStart
 startSet n = startingUsualMessages "mincopies" ai si $ do
-	setGlobalMinCopies $ MinCopies n
+	setGlobalMinCopies $ configuredMinCopies n
 	next $ return True
   where
 	ai = ActionItemOther (Just $ show n)

Command/NumCopies.hs

@@ -8,7 +8,6 @@
 module Command.NumCopies where
 
 import Command
-import qualified Annex
 import Annex.NumCopies
 
 cmd :: Command
@@ -28,11 +27,8 @@ start' setting _ startset [s] = case readish s of
 	Nothing -> giveup $ "Bad number: " ++ s
 	Just n
 		| n > 0 -> startset n
-		| n == 0 -> ifM (Annex.getState Annex.force)
-			( startset n
-			, giveup $ "Setting " ++ setting ++ " to 0 is very unsafe. You will lose data! If you really want to do that, specify --force."
-			)
-		| otherwise -> giveup "Number cannot be negative!"
+		| n == 0 -> giveup $ "Cannot set " ++ setting ++ " to 0."
+		| otherwise -> giveup $ setting ++ " cannot be negative!"
 start' _ _ _ _ = giveup "Specify a single number."
 
 startGet :: CommandStart
@@ -50,7 +46,7 @@ startGet = startingCustomOutput (ActionItemOther Nothing) $ next $ do
 
 startSet :: Int -> CommandStart
 startSet n = startingUsualMessages "numcopies" ai si $ do
-	setGlobalNumCopies $ NumCopies n
+	setGlobalNumCopies $ configuredNumCopies n
 	next $ return True
   where
 	ai = ActionItemOther (Just $ show n)

Command/Vicfg.hs

@@ -315,7 +315,7 @@ parseCfg defcfg = go [] defcfg . lines
 			in Right $ cfg { cfgGlobalConfigs = m }
 		| setting == "numcopies" = case readish val of
 			Nothing -> Left "parse error (expected an integer)"
-			Just n -> Right $ cfg { cfgNumCopies = Just (NumCopies n) }
+			Just n -> Right $ cfg { cfgNumCopies = Just (configuredNumCopies n) }
 		| otherwise = badval "setting" setting
 	  where
 		u = toUUID f