1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
{- git-annex SHA backends
-
- Copyright 2011,2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Backend.SHA (backends) where
import Common.Annex
import qualified Annex
import Types.Backend
import Types.Key
import Types.KeySource
import Utility.ExternalSHA
import qualified Build.SysConfig as SysConfig
import Data.Digest.Pure.SHA
import qualified Data.ByteString.Lazy as L
import Data.Char
type SHASize = Int
{- Order is slightly significant; want SHA256 first, and more general
- sizes earlier. -}
sizes :: [Int]
sizes = [256, 1, 512, 224, 384]
{- The SHA256E backend is the default. -}
backends :: [Backend]
backends = catMaybes $ map genBackendE sizes ++ map genBackend sizes
genBackend :: SHASize -> Maybe Backend
genBackend size = Just $ Backend
{ name = shaName size
, getKey = keyValue size
, fsckKey = Just $ checkKeyChecksum size
, canUpgradeKey = Just $ needsUpgrade
}
genBackendE :: SHASize -> Maybe Backend
genBackendE size = do
b <- genBackend size
return $ b
{ name = shaNameE size
, getKey = keyValueE size
}
shaName :: SHASize -> String
shaName size = "SHA" ++ show size
shaNameE :: SHASize -> String
shaNameE size = shaName size ++ "E"
shaN :: SHASize -> FilePath -> Integer -> Annex String
shaN shasize file filesize = do
showAction "checksum"
liftIO $ case shaCommand shasize filesize of
Left sha -> sha <$> L.readFile file
Right command ->
either error return
=<< externalSHA command shasize file
shaCommand :: SHASize -> Integer -> Either (L.ByteString -> String) String
shaCommand shasize filesize
| shasize == 1 = use SysConfig.sha1 sha1
| shasize == 256 = use SysConfig.sha256 sha256
| shasize == 224 = use SysConfig.sha224 sha224
| shasize == 384 = use SysConfig.sha384 sha384
| shasize == 512 = use SysConfig.sha512 sha512
| otherwise = error $ "bad sha size " ++ show shasize
where
use Nothing sha = Left $ showDigest . sha
use (Just c) sha
{- use builtin, but slower sha for small files
- benchmarking indicates it's faster up to
- and slightly beyond 50 kb files -}
| filesize < 51200 = use Nothing sha
| otherwise = Right c
{- A key is a checksum of its contents. -}
keyValue :: SHASize -> KeySource -> Annex (Maybe Key)
keyValue shasize source = do
let file = contentLocation source
stat <- liftIO $ getFileStatus file
let filesize = fromIntegral $ fileSize stat
s <- shaN shasize file filesize
return $ Just $ stubKey
{ keyName = s
, keyBackendName = shaName shasize
, keySize = Just filesize
}
{- Extension preserving keys. -}
keyValueE :: SHASize -> KeySource -> Annex (Maybe Key)
keyValueE size source = keyValue size source >>= maybe (return Nothing) addE
where
addE k = return $ Just $ k
{ keyName = keyName k ++ selectExtension (keyFilename source)
, keyBackendName = shaNameE size
}
selectExtension :: FilePath -> String
selectExtension f
| null es = ""
| otherwise = intercalate "." ("":es)
where
es = filter (not . null) $ reverse $
take 2 $ takeWhile shortenough $
reverse $ split "." $ filter validExtension $ takeExtensions f
shortenough e = length e <= 4 -- long enough for "jpeg"
{- A key's checksum is checked during fsck. -}
checkKeyChecksum :: SHASize -> Key -> FilePath -> Annex Bool
checkKeyChecksum size key file = do
fast <- Annex.getState Annex.fast
mstat <- liftIO $ catchMaybeIO $ getFileStatus file
case (mstat, fast) of
(Just stat, False) -> do
let filesize = fromIntegral $ fileSize stat
check <$> shaN size file filesize
_ -> return True
where
sha = keySha key
check s
| s == sha = True
{- A bug caused checksums to be prefixed with \ in some
- cases; still accept these as legal now that the bug has been
- fixed. -}
| '\\' : s == sha = True
| otherwise = False
keySha :: Key -> String
keySha key = dropExtensions (keyName key)
validExtension :: Char -> Bool
validExtension c
| isAlphaNum c = True
| c == '.' = True
| otherwise = False
{- Upgrade keys that have the \ prefix on their sha due to a bug, or
- that contain non-alphanumeric characters in their extension. -}
needsUpgrade :: Key -> Bool
needsUpgrade key = "\\" `isPrefixOf` keySha key ||
any (not . validExtension) (takeExtensions $ keyName key)
|
