Merge branch 'nd/per-worktree-ref-iteration'

The code to traverse objects for reachability, used to decide what
objects are unreferenced and expendable, have been taught to also
consider per-worktree refs of other worktrees as starting points to
prevent data loss.

* nd/per-worktree-ref-iteration:
  git-worktree.txt: correct linkgit command name
  reflog expire: cover reflog from all worktrees
  fsck: check HEAD and reflog from other worktrees
  fsck: move fsck_head_link() to get_default_heads() to avoid some globals
  revision.c: better error reporting on ref from different worktrees
  revision.c: correct a parameter name
  refs: new ref types to make per-worktree refs visible to all worktrees
  Add a place for (not) sharing stuff between worktrees
  refs.c: indent with tabs, not spaces

4 files changed, 131 insertions, 0 deletions

diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
index cd74c0a..c7b53e4 100755
--- a/t/t0060-path-utils.sh
+++ b/t/t0060-path-utils.sh
@@ -306,6 +306,8 @@ test_git_path GIT_COMMON_DIR=bar hooks/me                 bar/hooks/me
 test_git_path GIT_COMMON_DIR=bar config                   bar/config
 test_git_path GIT_COMMON_DIR=bar packed-refs              bar/packed-refs
 test_git_path GIT_COMMON_DIR=bar shallow                  bar/shallow
+test_git_path GIT_COMMON_DIR=bar common                   bar/common
+test_git_path GIT_COMMON_DIR=bar common/file              bar/common/file
 
 # In the tests below, $(pwd) must be used because it is a native path on
 # Windows and avoids MSYS's path mangling (which simplifies "foo/../bar" and
diff --git a/t/t1410-reflog.sh b/t/t1410-reflog.sh
index 388b061..3e05353 100755
--- a/t/t1410-reflog.sh
+++ b/t/t1410-reflog.sh
@@ -368,4 +368,19 @@ test_expect_success 'continue walking past root commits' '
 	)
 '
 
+test_expect_success 'expire with multiple worktrees' '
+	git init main-wt &&
+	(
+		cd main-wt &&
+		test_tick &&
+		test_commit foo &&
+		git  worktree add link-wt &&
+		test_tick &&
+		test_commit -C link-wt foobar &&
+		test_tick &&
+		git reflog expire --verbose --all --expire=$test_tick &&
+		test_must_be_empty .git/worktrees/link-wt/logs/HEAD
+	)
+'
+
 test_done
diff --git a/t/t1415-worktree-refs.sh b/t/t1415-worktree-refs.sh
new file mode 100755
index 0000000..b664e51
--- /dev/null
+++ b/t/t1415-worktree-refs.sh
@@ -0,0 +1,79 @@
+#!/bin/sh
+
+test_description='per-worktree refs'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_commit initial &&
+	test_commit wt1 &&
+	test_commit wt2 &&
+	git worktree add wt1 wt1 &&
+	git worktree add wt2 wt2 &&
+	git checkout initial &&
+	git update-ref refs/worktree/foo HEAD &&
+	git -C wt1 update-ref refs/worktree/foo HEAD &&
+	git -C wt2 update-ref refs/worktree/foo HEAD
+'
+
+test_expect_success 'refs/worktree must not be packed' '
+	git pack-refs --all &&
+	test_path_is_missing .git/refs/tags/wt1 &&
+	test_path_is_file .git/refs/worktree/foo &&
+	test_path_is_file .git/worktrees/wt1/refs/worktree/foo &&
+	test_path_is_file .git/worktrees/wt2/refs/worktree/foo
+'
+
+test_expect_success 'refs/worktree are per-worktree' '
+	test_cmp_rev worktree/foo initial &&
+	( cd wt1 && test_cmp_rev worktree/foo wt1 ) &&
+	( cd wt2 && test_cmp_rev worktree/foo wt2 )
+'
+
+test_expect_success 'resolve main-worktree/HEAD' '
+	test_cmp_rev main-worktree/HEAD initial &&
+	( cd wt1 && test_cmp_rev main-worktree/HEAD initial ) &&
+	( cd wt2 && test_cmp_rev main-worktree/HEAD initial )
+'
+
+test_expect_success 'ambiguous main-worktree/HEAD' '
+	mkdir -p .git/refs/heads/main-worktree &&
+	test_when_finished rm -f .git/refs/heads/main-worktree/HEAD &&
+	cp .git/HEAD .git/refs/heads/main-worktree/HEAD &&
+	git rev-parse main-worktree/HEAD 2>warn &&
+	grep "main-worktree/HEAD.*ambiguous" warn
+'
+
+test_expect_success 'resolve worktrees/xx/HEAD' '
+	test_cmp_rev worktrees/wt1/HEAD wt1 &&
+	( cd wt1 && test_cmp_rev worktrees/wt1/HEAD wt1 ) &&
+	( cd wt2 && test_cmp_rev worktrees/wt1/HEAD wt1 )
+'
+
+test_expect_success 'ambiguous worktrees/xx/HEAD' '
+	mkdir -p .git/refs/heads/worktrees/wt1 &&
+	test_when_finished rm -f .git/refs/heads/worktrees/wt1/HEAD &&
+	cp .git/HEAD .git/refs/heads/worktrees/wt1/HEAD &&
+	git rev-parse worktrees/wt1/HEAD 2>warn &&
+	grep "worktrees/wt1/HEAD.*ambiguous" warn
+'
+
+test_expect_success 'reflog of main-worktree/HEAD' '
+	git reflog HEAD | sed "s/HEAD/main-worktree\/HEAD/" >expected &&
+	git reflog main-worktree/HEAD >actual &&
+	test_cmp expected actual &&
+	git -C wt1 reflog main-worktree/HEAD >actual.wt1 &&
+	test_cmp expected actual.wt1
+'
+
+test_expect_success 'reflog of worktrees/xx/HEAD' '
+	git -C wt2 reflog HEAD | sed "s/HEAD/worktrees\/wt2\/HEAD/" >expected &&
+	git reflog worktrees/wt2/HEAD >actual &&
+	test_cmp expected actual &&
+	git -C wt1 reflog worktrees/wt2/HEAD >actual.wt1 &&
+	test_cmp expected actual.wt1 &&
+	git -C wt2 reflog worktrees/wt2/HEAD >actual.wt2 &&
+	test_cmp expected actual.wt2
+'
+
+test_done
diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh
index b5677d2..e20e8fa 100755
--- a/t/t1450-fsck.sh
+++ b/t/t1450-fsck.sh
@@ -101,6 +101,41 @@ test_expect_success 'HEAD link pointing at a funny place' '
 	grep "HEAD points to something strange" out
 '
 
+test_expect_success 'HEAD link pointing at a funny object (from different wt)' '
+	test_when_finished "mv .git/SAVED_HEAD .git/HEAD" &&
+	test_when_finished "rm -rf .git/worktrees wt" &&
+	git worktree add wt &&
+	mv .git/HEAD .git/SAVED_HEAD &&
+	echo $ZERO_OID >.git/HEAD &&
+	# avoid corrupt/broken HEAD from interfering with repo discovery
+	test_must_fail git -C wt fsck 2>out &&
+	grep "main-worktree/HEAD: detached HEAD points" out
+'
+
+test_expect_success 'other worktree HEAD link pointing at a funny object' '
+	test_when_finished "rm -rf .git/worktrees other" &&
+	git worktree add other &&
+	echo $ZERO_OID >.git/worktrees/other/HEAD &&
+	test_must_fail git fsck 2>out &&
+	grep "worktrees/other/HEAD: detached HEAD points" out
+'
+
+test_expect_success 'other worktree HEAD link pointing at missing object' '
+	test_when_finished "rm -rf .git/worktrees other" &&
+	git worktree add other &&
+	echo "Contents missing from repo" | git hash-object --stdin >.git/worktrees/other/HEAD &&
+	test_must_fail git fsck 2>out &&
+	grep "worktrees/other/HEAD: invalid sha1 pointer" out
+'
+
+test_expect_success 'other worktree HEAD link pointing at a funny place' '
+	test_when_finished "rm -rf .git/worktrees other" &&
+	git worktree add other &&
+	echo "ref: refs/funny/place" >.git/worktrees/other/HEAD &&
+	test_must_fail git fsck 2>out &&
+	grep "worktrees/other/HEAD points to something strange" out
+'
+
 test_expect_success 'email without @ is okay' '
 	git cat-file commit HEAD >basis &&
 	sed "s/@/AT/" basis >okay &&