Bug in filter-branch -d option, new files are dumped into parent

Bug in filter-branch -d option, new files are dumped into parent

[Martin Erik Werner]

Hi,
I think I have stumbled on a bug in the -d option of git filter-branch.

It seems like in the final stage of filter-branch, regardless of where
-d is set, it will make updates to the "working directory" as being the
parent of the -d directory, and the actual working directory is left as
it were before the filtering.

For example if using -d /tmp/git-rewrite, the new checkout files are
dumped into /tmp.

A simple test scenario:

###
mkdir test
cd test
git init

echo foo >foo
git add foo
git commit -m"foo"
echo bar >bar
git add bar
git commit -m"bar"

git checkout -b rewrite
git filter-branch -d /tmp/git-rewrite --tree-filter 'echo baz >baz' --
rewrite
# git status
# shows 'baz' as unstaged-deleted in the working directory
#
# ls /tmp/
# shows the 'baz' file created in the root, above git-rewrite
#
# git log --stat --oneline
# does show expected result though
#
# if you run it again you'll get an error because of the /tmp/baz file
git reset --hard master
git filter-branch -f -d /tmp/git-rewrite --tree-filter 'echo baz >baz'
-- rewrite
# Rewrite afac18542ac3d432b647866f5ac6918b81b3bb78 (2/2)
# Ref 'refs/heads/rewrite' was rewritten
# error: Untracked working tree file 'baz' would be overwritten by
merge.
#
# At this point, 'baz' is instead staged-deleted in the working
directory
###

-- 
Martin Erik Werner <martinerikwerner@gmail.com>

[PATCH] filter-branch: return to original dir after filtering

[Jeff King]

The first thing filter-branch does is to create a temporary
directory, either ".git-rewrite" in the current directory
(which may be the working tree or the repository if bare),
or in a directory specified by "-d". We then chdir to
$tempdir/t as our temporary working directory in which to run
tree filters.

After finishing the filter, we then attempt to go back to
the original directory with "cd ../..". This works in the
.git-rewrite case, but if "-d" is used, we end up in a
random directory. The only thing we do after this chdir is
to run git-read-tree, but that means that:

  1. The working directory is not updated to reflect the
     filtered history.

  2. We dump random files into "$tempdir/.." (e.g., if you
     use "-d /tmp/foo", we dump junk into /tmp).

Fix it by recording the full path to the original directory
and returning there explicitly.

Signed-off-by: Jeff King <peff@peff.net>
---
On Tue, Apr 02, 2013 at 02:32:21PM +0200, Martin Erik Werner wrote:

> I think I have stumbled on a bug in the -d option of git filter-branch.
> 
> It seems like in the final stage of filter-branch, regardless of where
> -d is set, it will make updates to the "working directory" as being the
> parent of the -d directory, and the actual working directory is left as
> it were before the filtering.

Yep, definitely a bug. Thanks for reporting.

 git-filter-branch.sh     |  5 +++--
 t/t7003-filter-branch.sh | 14 ++++++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 5314249..ac2a005 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -199,6 +199,7 @@ esac
 	test -d "$tempdir" &&
 		die "$tempdir already exists, please remove it"
 esac
+orig_dir=$(pwd)
 mkdir -p "$tempdir/t" &&
 tempdir="$(cd "$tempdir"; pwd)" &&
 cd "$tempdir/t" &&
@@ -206,7 +207,7 @@ die ""
 die ""
 
 # Remove tempdir on exit
-trap 'cd ../..; rm -rf "$tempdir"' 0
+trap 'cd "$orig_dir"; rm -rf "$tempdir"' 0
 
 ORIG_GIT_DIR="$GIT_DIR"
 ORIG_GIT_WORK_TREE="$GIT_WORK_TREE"
@@ -469,7 +470,7 @@ fi
 	done
 fi
 
-cd ../..
+cd "$orig_dir"
 rm -rf "$tempdir"
 
 trap - 0
diff --git a/t/t7003-filter-branch.sh b/t/t7003-filter-branch.sh
index 1e7a209..9496736 100755
--- a/t/t7003-filter-branch.sh
+++ b/t/t7003-filter-branch.sh
@@ -64,6 +64,20 @@ test_expect_success 'correct GIT_DIR while using -d' '
 	grep drepo "$TRASHDIR/backup-refs"
 '
 
+test_expect_success 'tree-filter works with -d' '
+	git init drepo-tree &&
+	(
+		cd drepo-tree &&
+		test_commit one &&
+		git filter-branch -d "$TRASHDIR/dfoo" \
+			--tree-filter "echo changed >one.t" &&
+		echo changed >expect &&
+		git cat-file blob HEAD:one.t >actual &&
+		test_cmp expect actual &&
+		test_cmp one.t actual
+	)
+'
+
 test_expect_success 'Fail if commit filter fails' '
 	test_must_fail git filter-branch -f --commit-filter "exit 1" HEAD
 '
-- 
1.8.2.rc0.33.gd915649