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
147
148
149
150
151
|
{- git-annex key-value storage backends
-
- git-annex uses a key-value abstraction layer to allow files contents to be
- stored in different ways. In theory, any key-value storage system could be
- used to store the file contents, and git-annex would then retrieve them
- as needed and put them in `.git/annex/`.
-
- When a file is annexed, a key is generated from its content and/or metadata.
- This key can later be used to retrieve the file's content (its value). This
- key generation must be stable for a given file content, name, and size.
-
- Multiple pluggable backends are supported, and more than one can be used
- to store different files' contents in a given repository.
-
- Copyright 2010 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Backend (
list,
storeFileKey,
retrieveKeyFile,
removeKey,
hasKey,
lookupFile,
chooseBackends
) where
import Control.Monad.State
import IO (try)
import System.FilePath
import System.Posix.Files
import Core
import Locations
import qualified GitRepo as Git
import qualified Annex
import Types
import qualified TypeInternals as Internals
{- List of backends in the order to try them when storing a new key. -}
list :: Annex [Backend]
list = do
l <- Annex.backends -- list is cached here
if (not $ null l)
then return l
else do
bs <- Annex.supportedBackends
g <- Annex.gitRepo
let defaults = parseBackendList bs $ Git.configGet g "annex.backends" ""
backendflag <- Annex.flagGet "backend"
let l' = if (not $ null backendflag)
then (lookupBackendName bs backendflag):defaults
else defaults
Annex.backendsChange l'
return l'
where
parseBackendList bs s =
if (null s)
then bs
else map (lookupBackendName bs) $ words s
{- Looks up a backend in a list. May fail if unknown. -}
lookupBackendName :: [Backend] -> String -> Backend
lookupBackendName bs s =
case maybeLookupBackendName bs s of
Just b -> b
Nothing -> error $ "unknown backend " ++ s
maybeLookupBackendName :: [Backend] -> String -> Maybe Backend
maybeLookupBackendName bs s =
if ((length matches) /= 1)
then Nothing
else Just $ head matches
where matches = filter (\b -> s == Internals.name b) bs
{- Attempts to store a file in one of the backends. -}
storeFileKey :: FilePath -> Maybe Backend -> Annex (Maybe (Key, Backend))
storeFileKey file trybackend = do
g <- Annex.gitRepo
let relfile = Git.relative g file
bs <- list
let bs' = case trybackend of
Nothing -> bs
Just backend -> backend:bs
storeFileKey' bs' file relfile
storeFileKey' :: [Backend] -> FilePath -> FilePath -> Annex (Maybe (Key, Backend))
storeFileKey' [] _ _ = return Nothing
storeFileKey' (b:bs) file relfile = do
result <- (Internals.getKey b) relfile
case result of
Nothing -> nextbackend
Just key -> do
stored <- (Internals.storeFileKey b) file key
if (not stored)
then nextbackend
else return $ Just (key, b)
where
nextbackend = storeFileKey' bs file relfile
{- Attempts to retrieve an key from one of the backends, saving it to
- a specified location. -}
retrieveKeyFile :: Backend -> Key -> FilePath -> Annex Bool
retrieveKeyFile backend key dest = (Internals.retrieveKeyFile backend) key dest
{- Removes a key from a backend. -}
removeKey :: Backend -> Key -> Annex Bool
removeKey backend key = (Internals.removeKey backend) key
{- Checks if a key is present in its backend. -}
hasKey :: Key -> Annex Bool
hasKey key = do
bs <- Annex.supportedBackends
(Internals.hasKey (lookupBackendName bs $ backendName key)) key
{- Looks up the key and backend corresponding to an annexed file,
- by examining what the file symlinks to. -}
lookupFile :: FilePath -> Annex (Maybe (Key, Backend))
lookupFile file = do
bs <- Annex.supportedBackends
tl <- liftIO $ try getsymlink
case tl of
Left _ -> return Nothing
Right l -> makekey bs l
where
getsymlink = do
l <- readSymbolicLink file
return $ takeFileName l
makekey bs l =
case maybeLookupBackendName bs bname of
Nothing -> do
unless (null kname || null bname) $
warning skip
return Nothing
Just backend -> return $ Just (k, backend)
where
k = fileKey l
bname = backendName k
kname = keyName k
skip = "skipping " ++ file ++
" (unknown backend " ++ bname ++ ")"
{- Looks up the backends that should be used for each file in a list.
- That can be configured on a per-file basis in the gitattributes file.
-}
chooseBackends :: [FilePath] -> Annex [(FilePath, Maybe Backend)]
chooseBackends fs = do
g <- Annex.gitRepo
bs <- Annex.supportedBackends
pairs <- liftIO $ Git.checkAttr g "git-annex-backend" fs
return $ map (\(f,b) -> (f, maybeLookupBackendName bs b)) pairs
|
