git-annex/CmdLine/Batch.hs
Joey Hess 1d1054faa6
added -z
Added -z option to git-annex commands that use --batch, useful for
supporting filenames containing newlines.

It only controls input to --batch, the output will still be line delimited
unless --json or etc is used to get some other output. While git often
makes -z affect both input and output, I don't like trying them together,
and making it affect output would have been a significant complication,
and also git-annex output is generally not intended to be machine parsed,
unless using --json or a format option.

Commands that take pairs like "file key" still separate them with a space
in --batch mode. All such commands take care to support filenames with
spaces when parsing that, so there was no need to change it, and it would
have needed significant changes to the batch machinery to separate tose
with a null.

To make fromkey and registerurl support -z, I had to give them a --batch
option. The implicit batch mode they enter when not provided with input
parameters does not support -z as that would have complicated option
parsing. Seemed better to move these toward using the same --batch as
everything else, though the implicit batch mode can still be used.

This commit was sponsored by Ole-Morten Duesund on Patreon.
2018-09-20 16:11:47 -04:00

108 lines
3.2 KiB
Haskell

{- git-annex batch commands
-
- Copyright 2015 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module CmdLine.Batch where
import Annex.Common
import Types.Command
import CmdLine.Action
import CmdLine.GitAnnex.Options
import Options.Applicative
import Limit
import Types.FileMatcher
data BatchMode = Batch BatchFormat | NoBatch
data BatchFormat = BatchLine | BatchNull
parseBatchOption :: Parser BatchMode
parseBatchOption = go
<$> switch
( long "batch"
<> help "enable batch mode"
)
<*> switch
( short 'z'
<> help "null delimited batch input"
)
where
go True False = Batch BatchLine
go True True = Batch BatchNull
go False _ = NoBatch
-- A batchable command can run in batch mode, or not.
-- In batch mode, one line at a time is read, parsed, and a reply output to
-- stdout. In non batch mode, the command's parameters are parsed and
-- a reply output for each.
batchable :: (opts -> String -> Annex Bool) -> Parser opts -> CmdParamsDesc -> CommandParser
batchable handler parser paramdesc = batchseeker <$> batchparser
where
batchparser = (,,)
<$> parser
<*> parseBatchOption
<*> cmdParams paramdesc
batchseeker (opts, NoBatch, params) =
mapM_ (go NoBatch opts) params
batchseeker (opts, batchmode@(Batch fmt), _) =
batchInput fmt Right (go batchmode opts)
go batchmode opts p =
unlessM (handler opts p) $
batchBadInput batchmode
-- bad input is indicated by an empty line in batch mode. In non batch
-- mode, exit on bad input.
batchBadInput :: BatchMode -> Annex ()
batchBadInput NoBatch = liftIO exitFailure
batchBadInput (Batch _) = liftIO $ putStrLn ""
-- Reads lines of batch mode input and passes to the action to handle.
batchInput :: BatchFormat -> (String -> Either String a) -> (a -> Annex ()) -> Annex ()
batchInput fmt parser a = go =<< batchLines fmt
where
go [] = return ()
go (l:rest) = do
either parseerr a (parser l)
go rest
parseerr s = giveup $ "Batch input parse failure: " ++ s
batchLines :: BatchFormat -> Annex [String]
batchLines fmt = liftIO $ splitter <$> getContents
where
splitter = case fmt of
BatchLine -> lines
BatchNull -> splitc '\0'
-- Runs a CommandStart in batch mode.
--
-- The batch mode user expects to read a line of output, and it's up to the
-- CommandStart to generate that output as it succeeds or fails to do its
-- job. However, if it stops without doing anything, it won't generate
-- any output, so in that case, batchBadInput is used to provide the caller
-- with an empty line.
batchCommandAction :: CommandStart -> Annex ()
batchCommandAction a = maybe (batchBadInput (Batch BatchLine)) (const noop)
=<< callCommandAction' a
-- Reads lines of batch input and passes the filepaths to a CommandStart
-- to handle them.
--
-- File matching options are not checked.
allBatchFiles :: BatchFormat -> (FilePath -> CommandStart) -> Annex ()
allBatchFiles fmt a = batchInput fmt Right $ batchCommandAction . a
-- Like allBatchFiles, but checks the file matching options
-- and skips non-matching files.
batchFilesMatching :: BatchFormat -> (FilePath -> CommandStart) -> Annex ()
batchFilesMatching fmt a = do
matcher <- getMatcher
allBatchFiles fmt $ \f ->
ifM (matcher $ MatchingFile $ FileInfo f f)
( a f
, return Nothing
)