git-annex/Command/NumCopies.hs
Joey Hess d266a41f8d
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
2022-03-28 15:20:34 -04:00

53 lines
1.6 KiB
Haskell

{- git-annex command
-
- Copyright 2014-2021 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Command.NumCopies where
import Command
import Annex.NumCopies
cmd :: Command
cmd = noMessages $ command "numcopies" SectionSetup
"configure desired number of copies"
paramNumber (withParams seek)
seek :: CmdParams -> CommandSeek
seek = withWords (commandAction . start)
start :: [String] -> CommandStart
start = start' "numcopies" startGet startSet
start' :: String -> CommandStart -> (Int -> CommandStart) -> [String] -> CommandStart
start' _ startget _ [] = startget
start' setting _ startset [s] = case readish s of
Nothing -> giveup $ "Bad number: " ++ s
Just n
| n > 0 -> startset n
| n == 0 -> giveup $ "Cannot set " ++ setting ++ " to 0."
| otherwise -> giveup $ setting ++ " cannot be negative!"
start' _ _ _ _ = giveup "Specify a single number."
startGet :: CommandStart
startGet = startingCustomOutput (ActionItemOther Nothing) $ next $ do
v <- getGlobalNumCopies
case v of
Just n -> liftIO $ putStrLn $ show $ fromNumCopies n
Nothing -> do
liftIO $ putStrLn "global numcopies is not set"
old <- deprecatedNumCopies
case old of
Nothing -> liftIO $ putStrLn "(default is 1)"
Just n -> liftIO $ putStrLn $ "(deprecated git config annex.numcopies is set to " ++ show (fromNumCopies n) ++ " locally)"
return True
startSet :: Int -> CommandStart
startSet n = startingUsualMessages "numcopies" ai si $ do
setGlobalNumCopies $ configuredNumCopies n
next $ return True
where
ai = ActionItemOther (Just $ show n)
si = SeekInput [show n]