Re: [RFD] git stash over OpenBSD/Linux NFS - cp -p breakage

From: Johannes Sixt <j.sixt@viscovery.net>
Date: Mar 15, 2011, 10:58 UTC
Message-ID: <4D7F466A.4090508@viscovery.net>
In-Reply-To: <4D7F3AA4.1080202@elegosoft.com>

Am 3/15/2011 11:08, schrieb Jakob Pfender:

Show 19 quoted lines

> We have an NFS setup with Linux machines mounting an NFS that is hosted on
> an OpenBSD server. Recently, we discovered git-stash breaking with:
> 
> $ git stash
> cp: preserving permissions for
> `/home/jpfender/stashtest/.git/.git-stash.3056-index': Operation not
> supported
> Cannot save the current worktree state
> 
> This was discovered to be caused by a bug in cp that causes 'cp -p' to
> fail in this particular NFS setup - preserving permissions in an NFS
> shared across Linux and OpenBSD machines doesn't work.
> 
> I looked at git-stash.sh and could not discover a reason why it had to use
> 'cp -p'. I patched it to use only cp without preserving permissions, and
> everything seemed to work fine. All stash tests succeeded (bar two known
> breakages).
> 
> So my question is: Does git-stash really need 'cp -p'? Is it safe to remove?

Yes. No.

The timestamp of the index file is important. It is needed to discover racily-clean index entries. Therefore, the -p must remain.

You can also try the patch below. Warning: completely untested.

-- Hannes

diff --git a/git-stash.sh b/git-stash.sh
index 7561b37..fa62135 100755
--- a/git-stash.sh
+++ b/git-stash.sh
@@ -82,10 +82,9 @@ create_stash () {
 		# state of the working tree
 		w_tree=$( (
 			rm -f "$TMP-index" &&
-			cp -p ${GIT_INDEX_FILE-"$GIT_DIR/index"} "$TMP-index" &&
+			git read-tree --index-output="$TMP-index" -m $i_tree &&
 			GIT_INDEX_FILE="$TMP-index" &&
 			export GIT_INDEX_FILE &&
-			git read-tree -m $i_tree &&
 			git diff --name-only -z HEAD | git update-index -z --add --remove --stdin &&
 			git write-tree &&
 			rm -f "$TMP-index"