git-annex/doc/tips/Using_git-annex_on_NTFS_with_WSL1.mdwn

The following steps are tested on Windows 10 21h1 with Ubuntu 20 and are designed to allow use of the annexed files through both WSL and Windows.

** Limitations **

* The repository must be created with `annex.tune.objecthashlower=true`.
* `git annex adjust --unlock` will not work. Avoid `annex.addunlocked=true` and do not add multiple unlocked files to the index.

**Setup**

* Enable Developer mode in Windows settings so that symlinks can be created without elevated privileges.
* Mount the NTFS drive with metadata option. [`/etc/wsl.conf`](https://docs.microsoft.com/en-us/windows/wsl/wsl-config) can be used or a line such as `C: /mnt/c drvfs metadata` can be added in `/etc/fstab`.
* Follow these steps in order when creating a new repository.
    * `git config annex.sshcaching false`
    * `git annex init`
    * git-annex should not detect the filesystem as crippled but now set `git config annex.crippledfilesystem true`
* Safety of locked files will require these settings and scripts.
    * `git config annex.freezecontent-command 'wsl-freezecontent %path'`
    * `git config annex.thawcontent-command 'wsl-thawcontent %path'`

<details>
<summary>wsl-freezecontent</summary>

```
#!/usr/bin/env bash

if [ -f "$1" ]; then
	if \[[ "$1" == *.git/annex/objects/* ]]; then
		PERM='(DE,WD,AD)'
	else
		PERM='(WD,AD)'
	fi
elif [ -d "$1" ]; then
	PERM='(DE,DC,WD,AD)'
else
	exit 0
fi

OUTPUT="$(icacls.exe "$(wslpath -w "$1")" /deny "Authenticated Users:$PERM")"

if [ "$?" -ne 0 ]; then
	echo "$OUTPUT"
	exit 1
fi

```
</details>

<details>
<summary>wsl-thawcontent</summary>

```
#!/usr/bin/env bash

if [ -f "$1" ]; then
	PERM='(DE,WD,AD)'
elif [ -d "$1" ]; then
	PERM='(DE,DC,WD,AD)'
else
	exit 0
fi

OUTPUT="$(icacls.exe "$(wslpath -w "$1")" /grant "Authenticated Users:$PERM")"

if [ "$?" -ne 0 ]; then
	echo "$OUTPUT"
	exit 1
fi

```
</details>

** Patches **

These patches may introduce problems when there are multiple independent processes writing to the repository. Use at your own risk.

<details>
<summary>Create symlink to annexed objects in-place. The add, addunused, lock, and rekey commands will create symlinks in-place instead of in a temporary directory.</summary>

```
From d871289d22d2e86cb62776841343baf6c0f83484 Mon Sep 17 00:00:00 2001
From: Reiko Asakura <asakurareiko@protonmail.ch>
Date: Wed, 12 Oct 2022 17:13:55 -0400
Subject: [PATCH 2/3] Create symlink to annexed objects in-place

---
 Annex/Ingest.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Annex/Ingest.hs b/Annex/Ingest.hs
index 89dc8acea..ec35fb15d 100644
--- a/Annex/Ingest.hs
+++ b/Annex/Ingest.hs
@@ -301,7 +301,7 @@ restoreFile file key e = do
 makeLink :: RawFilePath -> Key -> Maybe InodeCache -> Annex LinkTarget
 makeLink file key mcache = flip catchNonAsync (restoreFile file key) $ do
 	l <- calcRepo $ gitAnnexLink file key
-	replaceWorkTreeFile file' $ makeAnnexLink l . toRawFilePath
+	makeAnnexLink l file
 
 	-- touch symlink to have same time as the original file,
 	-- as provided in the InodeCache
-- 
2.30.2

```
</details>

<details>
<summary>Recreate symlinks after remote transfer. The copy, move, get, sync commands will recreate the symlink after transferring the file from a remote.</summary>

```
From 82ea0ffb02fbc5e4003a466a216c8d1030b7d70a Mon Sep 17 00:00:00 2001
From: Reiko Asakura <asakurareiko@protonmail.ch>
Date: Wed, 12 Oct 2022 19:10:07 -0400
Subject: [PATCH 3/3] Recreate symlinks after remote transfer

---
 Annex/Link.hs   | 7 +++++++
 Command/Get.hs  | 3 ++-
 Command/Move.hs | 3 ++-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/Annex/Link.hs b/Annex/Link.hs
index 1a344d07e..e0f172d1d 100644
--- a/Annex/Link.hs
+++ b/Annex/Link.hs
@@ -96,6 +96,13 @@ getAnnexLinkTarget' file coresymlinks = if coresymlinks
 					then mempty
 					else s
 
+relinkAssociatedFile :: AssociatedFile -> Bool -> Annex ()
+relinkAssociatedFile (AssociatedFile (Just file)) True =
+	getAnnexLinkTarget file >>= \case
+		Just target -> makeAnnexLink target file
+		_ -> noop
+relinkAssociatedFile _ _ = noop
+
 makeAnnexLink :: LinkTarget -> RawFilePath -> Annex ()
 makeAnnexLink = makeGitLink
 
diff --git a/Command/Get.hs b/Command/Get.hs
index a25fd8bf1..e16362f79 100644
--- a/Command/Get.hs
+++ b/Command/Get.hs
@@ -12,6 +12,7 @@ import qualified Remote
 import Annex.Transfer
 import Annex.NumCopies
 import Annex.Wanted
+import Annex.Link
 import qualified Command.Move
 
 cmd :: Command
@@ -95,7 +96,7 @@ getKey' key afile = dispatch
 		showNote "not available"
 		showlocs []
 		return False
-	dispatch remotes = notifyTransfer Download afile $ \witness -> do
+	dispatch remotes = observe (relinkAssociatedFile afile) $ notifyTransfer Download afile $ \witness -> do
 		ok <- pickRemote remotes $ \r -> ifM (probablyPresent r)
 			( docopy r witness
 			, return False
diff --git a/Command/Move.hs b/Command/Move.hs
index 55fed5c37..d733a7cbb 100644
--- a/Command/Move.hs
+++ b/Command/Move.hs
@@ -20,6 +20,7 @@ import Logs.Presence
 import Logs.Trust
 import Logs.File
 import Annex.NumCopies
+import Annex.Link
 
 import qualified Data.ByteString.Char8 as B8
 import qualified Data.ByteString.Lazy as L
@@ -241,7 +242,7 @@ fromPerform src removewhen key afile = do
 			then dispatch removewhen deststartedwithcopy True
 			else dispatch removewhen deststartedwithcopy =<< get
   where
-	get = notifyTransfer Download afile $
+	get = observe (relinkAssociatedFile afile) $ notifyTransfer Download afile $
 		download src key afile stdRetry
 	
 	dispatch _ deststartedwithcopy False = do
-- 
2.30.2

```
</details>

<details>
<summary>Allow git-annex fix on crippled filesystem</summary>

```
From 65fe6e362dfbf2f54c8da5ca17c59af26de5ff83 Mon Sep 17 00:00:00 2001
From: Reiko Asakura <asakurareiko@protonmail.ch>
Date: Sat, 23 Oct 2021 17:13:50 -0400
Subject: [PATCH 1/2] Allow git-annex fix on crippled filesystem

---
 Command/Fix.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Command/Fix.hs b/Command/Fix.hs
index 39853c894..2d66c1461 100644
--- a/Command/Fix.hs
+++ b/Command/Fix.hs
@@ -31,7 +31,7 @@ cmd = noCommit $ withAnnexOptions [annexedMatchingOptions] $
 		paramPaths (withParams seek)
 
 seek :: CmdParams -> CommandSeek
-seek ps = unlessM crippledFileSystem $
+seek ps =
 	withFilesInGitAnnex ww seeker =<< workTreeItems ww ps
   where
 	ww = WarnUnmatchLsFiles
-- 
2.30.2

```
</details>

** Usage tips **

* WSL1 will not create symlinks that work in Windows if created before the target file exists. This can be fixed by recreating them with any method, such as delete them and `git checkout`. Also see the above patches to make git-annex automatically recreate symlinks.

<details>
<summary>Sample script to recreate all symlinks under the current directory</summary>

```
#!/usr/bin/env python3

import pathlib
import os

def do(p):
	for c in list(p.iterdir()):
		if c.is_symlink() and c.resolve().exists():
			target = os.readlink(c) # use readlink here to get the relative link path
			c.unlink()
			c.symlink_to(target)
		elif c.is_dir() and c.name != '.git':
			do(c)

do(pathlib.Path('.'))
```
</details>

** Related bugs **

* [[bugs/WSL_adjusted_braches__58___smudge_fails_with_sqlite_thread_crashed_-_locking_protocol]]
* [[bugs/WSL1__58___git-annex-add_fails_in_DrvFs_filesystem]]