Use lowercase hash directories for locationlog files

to avoid some issues with git on OSX with the mixed-case directories. No
migration is needed; the old mixed case hash directories are still read;
new information is written to the new directories.

LocationLog.hs

@@ -23,7 +23,6 @@
 module LocationLog (
 	LogStatus(..),
 	logChange,
-	logFile,
 	readLog,
 	writeLog,
 	keyLocations
@@ -33,7 +32,6 @@ import Data.Time.Clock.POSIX
 import Data.Time
 import System.Locale
 import qualified Data.Map as Map
-import System.Directory
 import Control.Monad (when)
 
 import qualified GitRepo as Git
@@ -93,22 +91,16 @@ logChange repo key u s = do
 		error $ "unknown UUID for " ++ Git.repoDescribe repo ++ 
 			" (have you run git annex init there?)"
 	line <- logNow s u
-	ls <- readLog logfile
-	writeLog logfile (compactLog $ line:ls)
-	return logfile
-	where
-		logfile = logFile repo key
+	let f = logFile repo key
+	ls' <- readLog $ logFileOld repo key
+	ls <- readLog f
+	writeLog f (compactLog $ line:ls'++ls)
+	return f
 
 {- Reads a log file.
  - Note that the LogLines returned may be in any order. -}
 readLog :: FilePath -> IO [LogLine]
-readLog file = do
-	exists <- doesFileExist file
-	if exists
-		then do
-			s <- readFile file
-			return $ parseLog s
-		else return []
+readLog file = catch (return . parseLog =<< readFile file) (const $ return [])
 
 parseLog :: String -> [LogLine]
 parseLog s = filter parsable $ map read $ lines s
@@ -131,7 +123,8 @@ logNow s u = do
 keyLocations :: Git.Repo -> Key -> IO [UUID]
 keyLocations thisrepo key = do
 	ls <- readLog $ logFile thisrepo key
-	return $ map uuid $ filterPresent ls
+	ls' <- readLog $ logFileOld thisrepo key
+	return $ map uuid $ filterPresent $ ls'++ls
 
 {- Filters the list of LogLines to find ones where the value
  - is (or should still be) present. -}

Locations.hs

@@ -20,7 +20,8 @@ module Locations (
 	gitAnnexUnusedLog,
 	isLinkToAnnex,
 	logFile,
-	hashDir,
+	logFileOld,
+	hashDirMixed,
 
 	prop_idempotent_fileKey
 ) where
@@ -68,7 +69,7 @@ objectDir = addTrailingPathSeparator $ annexDir </> "objects"
 
 {- Annexed file's location relative to the .git directory. -}
 annexLocation :: Key -> FilePath
-annexLocation key = objectDir </> hashDir key </> f </> f
+annexLocation key = objectDir </> hashDirMixed key </> f </> f
 	where
 		f = keyFile key
 
@@ -113,8 +114,18 @@ isLinkToAnnex s = ("/.git/" ++ objectDir) `isInfixOf` s
 
 {- The filename of the log file for a given key. -}
 logFile :: Git.Repo -> Key -> String
-logFile repo key = 
-	gitStateDir repo ++ hashDir key ++ keyFile key ++ ".log"
+logFile = logFile' hashDirLower
+
+{- The old filename of the log file for a key. These can have mixed
+ - case, which turned out to be a bad idea for directories whose contents
+ - are checked into git. There was no conversion, so these have to be checked
+ - for and merged in at runtime. -}
+logFileOld :: Git.Repo -> Key -> String
+logFileOld = logFile' hashDirMixed
+
+logFile' :: (Key -> FilePath) -> Git.Repo -> Key -> String
+logFile' hasher repo key =
+	gitStateDir repo ++ hasher key ++ keyFile key ++ ".log"
 
 {- Converts a key into a filename fragment.
  -
@@ -147,13 +158,17 @@ prop_idempotent_fileKey s = Just k == fileKey (keyFile k)
 {- Given a key, generates a short directory name to put it in,
  - to do hashing to protect against filesystems that dislike having
  - many items in a single directory. -}
-hashDir :: Key -> FilePath
-hashDir k = addTrailingPathSeparator $ take 2 dir </> drop 2 dir
+hashDirMixed :: Key -> FilePath
+hashDirMixed k = addTrailingPathSeparator $ take 2 dir </> drop 2 dir
 	where
-		dir = take 4 $ abcd_to_dir $ md5 $ Str $ show k
+		dir = take 4 $ concat $ map display_32bits_as_dir [a,b,c,d]
+		ABCD (a,b,c,d) = md5 $ Str $ show k
 
-abcd_to_dir :: ABCD -> String
-abcd_to_dir (ABCD (a,b,c,d)) = concat $ map display_32bits_as_dir [a,b,c,d]
+{- Generates a hash directory that is all lower case. -}
+hashDirLower :: Key -> FilePath
+hashDirLower k = addTrailingPathSeparator $ take 3 dir </> drop 3 dir
+	where
+		dir = take 6 $ md5s $ Str $ show k
 
 {- modified version of display_32bits_as_hex from Data.Hash.MD5
  -   Copyright (C) 2001 Ian Lynagh 

Remote/Directory.hs

@@ -66,7 +66,7 @@ directorySetup u c = do
 	return $ M.delete "directory" c
 
 dirKey :: FilePath -> Key -> FilePath
-dirKey d k = d </> hashDir k </> f </> f
+dirKey d k = d </> hashDirMixed k </> f </> f
 	where
 		f = keyFile k
 

debian/changelog

@@ -1,3 +1,12 @@
+git-annex (0.20110402) UNRELEASED; urgency=low
+
+  * Use lowercase hash directories for locationlog files, to avoid
+    some issues with git on OSX with the mixed-case directories.
+    No migration is needed; the old mixed case hash directories are still
+    read; new information is written to the new directories.
+
+ -- Joey Hess <joeyh@debian.org>  Sat, 02 Apr 2011 13:45:54 -0400
+
 git-annex (0.20110401) experimental; urgency=low
 
   * Amazon S3 is now supported as a special type of remote.

doc/internals.mdwn

@@ -53,7 +53,7 @@ Example:
 	e605dca6-446a-11e0-8b2a-002170d25c55 1
 	26339d22-446b-11e0-9101-002170d25c55 ?
 
-## `.git-annex/aa/bb/*.log`
+## `.git-annex/aaa/bbb/*.log`
 
 The remainder of the log files record [[location_tracking]] information
 for file contents. Again these are placed in two levels of subdirectories