diff options
Diffstat (limited to 'Git/Sha.hs')
| -rw-r--r-- | Git/Sha.hs | 63 |
1 files changed, 47 insertions, 16 deletions
@@ -1,43 +1,74 @@ {- git SHA stuff - - - Copyright 2011 Joey Hess <id@joeyh.name> + - Copyright 2011,2020 Joey Hess <id@joeyh.name> - - Licensed under the GNU AGPL version 3 or higher. -} +{-# LANGUAGE OverloadedStrings #-} + module Git.Sha where import Common import Git.Types +import qualified Data.ByteString as S +import Data.Char + {- Runs an action that causes a git subcommand to emit a Sha, and strips - any trailing newline, returning the sha. -} -getSha :: String -> IO String -> IO Sha +getSha :: String -> IO S.ByteString -> IO Sha getSha subcommand a = maybe bad return =<< extractSha <$> a where bad = error $ "failed to read sha from git " ++ subcommand -{- Extracts the Sha from a string. There can be a trailing newline after - - it, but nothing else. -} -extractSha :: String -> Maybe Sha +{- Extracts the Sha from a ByteString. + - + - There can be a trailing newline after it, but nothing else. + -} +extractSha :: S.ByteString -> Maybe Sha extractSha s - | len == shaSize = val s - | len == shaSize + 1 && length s' == shaSize = val s' + | len `elem` shaSizes = val s + | len - 1 `elem` shaSizes && S.length s' == len - 1 = val s' | otherwise = Nothing where - len = length s - s' = firstLine s + len = S.length s + s' = firstLine' s val v - | all (`elem` "1234567890ABCDEFabcdef") v = Just $ Ref v + | S.all validinsha v = Just $ Ref v | otherwise = Nothing + validinsha w = or + [ w >= 48 && w <= 57 -- 0-9 + , w >= 97 && w <= 102 -- a-f + , w >= 65 && w <= 70 -- A-F + ] -{- Size of a git sha. -} -shaSize :: Int -shaSize = 40 +{- Sizes of git shas. -} +shaSizes :: [Int] +shaSizes = + [ 40 -- sha1 (must come first) + , 64 -- sha256 + ] -nullSha :: Ref -nullSha = Ref $ replicate shaSize '0' +{- Git plumbing often uses a all 0 sha to represent things like a + - deleted file. -} +nullShas :: [Sha] +nullShas = map (\n -> Ref (S.replicate n zero)) shaSizes + where + zero = fromIntegral (ord '0') -{- Git's magic empty tree. -} +{- Sha to provide to git plumbing when deleting a file. + - + - It's ok to provide a sha1; git versions that use sha256 will map the + - sha1 to the sha256, or probably just treat all null sha1 specially + - the same as all null sha256. -} +deleteSha :: Sha +deleteSha = Prelude.head nullShas + +{- Git's magic empty tree. + - + - It's ok to provide the sha1 of this to git to refer to an empty tree; + - git versions that use sha256 will map the sha1 to the sha256. + -} emptyTree :: Ref emptyTree = Ref "4b825dc642cb6eb9a060e54bf8d69288fbee4904" |