rename Git.Filename to Git.Quote

Git/Quote.hs

@@ -0,0 +1,122 @@
+{- 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