git-annex/Git/CheckAttr.hs
Joey Hess cd865c3b8f Switch to using relative paths to the git repository.
This allows the git repository to be moved while git-annex is running in
it, with fewer problems.

On Windows, this avoids some of the problems with the absurdly small
MAX_PATH of 260 bytes. In particular, git-annex repositories should
work in deeper/longer directory structures than before. See
http://git-annex.branchable.com/bugs/__34__git-annex:_direct:_1_failed__34___on_Windows/

There are several possible ways this change could break git-annex:

1. If it changes its working directory while it's running, that would
   be Bad News. Good news everyone! git-annex never does so. It would also
   break thread safety, so all such things were stomped out long ago.

2. parentDir "." -> "" which is not a valid path. I had to fix one
   instace of this, and I should probably wipe all calls to parentDir out
   of the git-annex code base; it was never a good idea.

3. Things like relPathDirToFile require absolute input paths,
   and code assumes that the git repo path is absolute and passes it to it
   as-is. In the case of relPathDirToFile, I converted it to not make
   this assumption.

Currently, the test suite has 16 failures.
2015-01-06 16:19:41 -04:00

93 lines
2.8 KiB
Haskell

{- git check-attr interface
-
- Copyright 2010-2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Git.CheckAttr where
import Common
import Git
import Git.Command
import qualified Git.Version
import qualified Utility.CoProcess as CoProcess
import System.IO.Error
type CheckAttrHandle = (CoProcess.CoProcessHandle, [Attr], Bool, String)
type Attr = String
{- Starts git check-attr running to look up the specified gitattributes
- values and returns a handle. -}
checkAttrStart :: [Attr] -> Repo -> IO CheckAttrHandle
checkAttrStart attrs repo = do
currdir <- getCurrentDirectory
h <- CoProcess.rawMode =<< gitCoProcessStart True params repo
oldgit <- Git.Version.older "1.7.7"
return (h, attrs, oldgit, currdir)
where
params =
[ Param "check-attr"
, Params "-z --stdin"
] ++ map Param attrs ++
[ Param "--" ]
checkAttrStop :: CheckAttrHandle -> IO ()
checkAttrStop (h, _, _, _) = CoProcess.stop h
{- Gets an attribute of a file. -}
checkAttr :: CheckAttrHandle -> Attr -> FilePath -> IO String
checkAttr (h, attrs, oldgit, currdir) want file = do
pairs <- CoProcess.query h send (receive "")
let vals = map snd $ filter (\(attr, _) -> attr == want) pairs
case vals of
[v] -> return v
_ -> error $ "unable to determine " ++ want ++ " attribute of " ++ file
where
send to = hPutStr to $ file' ++ "\0"
receive c from = do
s <- hGetSomeString from 1024
if null s
then eofError
else do
let v = c ++ s
maybe (receive v from) return (parse v)
eofError = ioError $ mkIOError userErrorType "git check-attr EOF" Nothing Nothing
parse s
-- new null separated output
| '\0' `elem` s = if "\0" `isSuffixOf` s
then
let bits = segment (== '\0') s
in if length bits == (numattrs * 3) + 1
then Just $ getattrvalues bits []
else Nothing -- more attributes to come
else Nothing -- output incomplete
-- old one line per value output
| otherwise = if "\n" `isSuffixOf` s
then
let ls = lines s
in if length ls == numattrs
then Just $ map (\(attr, val) -> (attr, oldattrvalue attr val))
(zip attrs ls)
else Nothing -- more attributes to come
else Nothing -- line incomplete
numattrs = length attrs
{- Before git 1.7.7, git check-attr worked best with
- absolute filenames; using them worked around some bugs
- with relative filenames.
-
- With newer git, git check-attr chokes on some absolute
- filenames, and the bugs that necessitated them were fixed,
- so use relative filenames. -}
file'
| oldgit = absPathFrom currdir file
| otherwise = relPathDirToFileAbs currdir $ absPathFrom currdir file
oldattrvalue attr l = end bits !! 0
where
bits = split sep l
sep = ": " ++ attr ++ ": "
getattrvalues (_filename:attr:val:rest) c = getattrvalues rest ((attr,val):c)
getattrvalues _ c = c