git-annex/Git/Quote.hs
2023-04-12 17:22:03 -04:00

122 lines
3.5 KiB
Haskell

{- Some git commands output quoted filenames, in a rather annoyingly complex
- C-style encoding.
-
- Copyright 2010-2023 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE OverloadedStrings, TypeSynonymInstances #-}
module Git.Quote (
unquote,
quote,
noquote,
QuotePath(..),
StringContainingQuotedPath(..),
quotedPaths,
prop_quote_unquote_roundtrip,
) where
import Common
import Utility.Format (decode_c, encode_c, encode_c', isUtf8Byte)
import Utility.QuickCheck
import Utility.SafeOutput
import Data.Char
import Data.Word
import Data.String
import qualified Data.ByteString as S
import qualified Data.Semigroup as Sem
import Prelude
unquote :: S.ByteString -> RawFilePath
unquote b = case S.uncons b of
Nothing -> b
Just (h, t)
| h /= q -> b
| otherwise -> case S.unsnoc t of
Nothing -> b
Just (i, l)
| l /= q -> b
| otherwise -> decode_c i
where
q :: Word8
q = fromIntegral (ord '"')
-- always encodes and double quotes, even in cases that git does not
quoteAlways :: RawFilePath -> S.ByteString
quoteAlways s = "\"" <> encode_c needencode s <> "\""
where
needencode c = isUtf8Byte c || c == fromIntegral (ord '"')
-- git config core.quotePath controls whether to quote unicode characters
newtype QuotePath = QuotePath Bool
class Quoteable t where
-- double quotes and encodes when git would
quote :: QuotePath -> t -> S.ByteString
noquote :: t -> S.ByteString
instance Quoteable RawFilePath where
quote (QuotePath qp) s = case encode_c' needencode s of
Nothing -> s
Just s' -> "\"" <> s' <> "\""
where
needencode c
| c == fromIntegral (ord '"') = True
| qp = isUtf8Byte c
| otherwise = False
noquote = id
-- Allows building up a string that contains paths, which will get quoted.
-- With OverloadedStrings, strings are passed through without quoting.
-- Eg: QuotedPath f <> ": not found"
data StringContainingQuotedPath
= UnquotedString String
| UnquotedByteString S.ByteString
| QuotedPath RawFilePath
| StringContainingQuotedPath :+: StringContainingQuotedPath
deriving (Show, Eq)
quotedPaths :: [RawFilePath] -> StringContainingQuotedPath
quotedPaths [] = mempty
quotedPaths (p:ps) = QuotedPath p <> if null ps
then mempty
else " " <> quotedPaths ps
instance Quoteable StringContainingQuotedPath where
quote _ (UnquotedString s) = safeOutput (encodeBS s)
quote _ (UnquotedByteString s) = safeOutput s
quote qp (QuotedPath p) = quote qp p
quote qp (a :+: b) = quote qp a <> quote qp b
noquote (UnquotedString s) = encodeBS s
noquote (UnquotedByteString s) = s
noquote (QuotedPath p) = p
noquote (a :+: b) = noquote a <> noquote b
instance IsString StringContainingQuotedPath where
fromString = UnquotedByteString . encodeBS
instance Sem.Semigroup StringContainingQuotedPath where
UnquotedString a <> UnquotedString b = UnquotedString (a <> b)
UnquotedByteString a <> UnquotedByteString b = UnquotedByteString (a <> b)
a <> b = a :+: b
instance Monoid StringContainingQuotedPath where
mempty = UnquotedByteString mempty
-- Encoding and then decoding roundtrips only when the string does not
-- contain high unicode, because eg, both "\12345" and "\227\128\185"
-- are encoded to "\343\200\271".
--
-- That is not a real-world problem, and using TestableFilePath
-- limits what's tested to ascii, so avoids running into it.
prop_quote_unquote_roundtrip :: TestableFilePath -> Bool
prop_quote_unquote_roundtrip ts =
s == fromRawFilePath (unquote (quoteAlways (toRawFilePath s)))
where
s = fromTestableFilePath ts