worktree: teach "repair" to fix outgoing links to worktrees

The .git/worktrees/<id>/gitdir file points at the location of a linked
worktree's .git file. Its content must be of the form
/path/to/worktree/.git (from which the location of the worktree itself
can be derived by stripping the "/.git" suffix). If the gitdir file is
deleted or becomes corrupted or outdated, then Git will be unable to
find the linked worktree. An easy way for the gitdir file to become
outdated is for the user to move the worktree manually (without using
"git worktree move"). Although it is possible to manually update the
gitdir file to reflect the new linked worktree location, doing so
requires a level of knowledge about worktree internals beyond what a
user should be expected to know offhand.

Therefore, teach "git worktree repair" how to repair broken or outdated
.git/worktrees/<id>/gitdir files automatically. (For this to work, the
command must either be invoked from within the worktree whose gitdir
file requires repair, or from within the main or any linked worktree by
providing the path of the broken worktree as an argument to "git
worktree repair".)

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 86 insertions, 0 deletions

diff --git a/t/t2406-worktree-repair.sh b/t/t2406-worktree-repair.sh
index ef59cdc..1fe468b 100755
--- a/t/t2406-worktree-repair.sh
+++ b/t/t2406-worktree-repair.sh
@@ -90,4 +90,90 @@ test_expect_success 'repair .git file from bare.git' '
 	test_cmp expect actual
 '
 
+test_expect_success 'invalid worktree path' '
+	test_must_fail git worktree repair /notvalid >out 2>err &&
+	test_must_be_empty out &&
+	test_i18ngrep "not a valid path" err
+'
+
+test_expect_success 'repo not found; .git not file' '
+	test_when_finished "rm -rf not-a-worktree" &&
+	test_create_repo not-a-worktree &&
+	test_must_fail git worktree repair not-a-worktree >out 2>err &&
+	test_must_be_empty out &&
+	test_i18ngrep ".git is not a file" err
+'
+
+test_expect_success 'repo not found; .git file broken' '
+	test_when_finished "rm -rf orig moved && git worktree prune" &&
+	git worktree add --detach orig &&
+	echo /invalid >orig/.git &&
+	mv orig moved &&
+	test_must_fail git worktree repair moved >out 2>err &&
+	test_must_be_empty out &&
+	test_i18ngrep ".git file broken" err
+'
+
+test_expect_success 'repair broken gitdir' '
+	test_when_finished "rm -rf orig moved && git worktree prune" &&
+	git worktree add --detach orig &&
+	sed s,orig/\.git$,moved/.git, .git/worktrees/orig/gitdir >expect &&
+	rm .git/worktrees/orig/gitdir &&
+	mv orig moved &&
+	git worktree repair moved >out 2>err &&
+	test_cmp expect .git/worktrees/orig/gitdir &&
+	test_i18ngrep "gitdir unreadable" out &&
+	test_must_be_empty err
+'
+
+test_expect_success 'repair incorrect gitdir' '
+	test_when_finished "rm -rf orig moved && git worktree prune" &&
+	git worktree add --detach orig &&
+	sed s,orig/\.git$,moved/.git, .git/worktrees/orig/gitdir >expect &&
+	mv orig moved &&
+	git worktree repair moved >out 2>err &&
+	test_cmp expect .git/worktrees/orig/gitdir &&
+	test_i18ngrep "gitdir incorrect" out &&
+	test_must_be_empty err
+'
+
+test_expect_success 'repair gitdir (implicit) from linked worktree' '
+	test_when_finished "rm -rf orig moved && git worktree prune" &&
+	git worktree add --detach orig &&
+	sed s,orig/\.git$,moved/.git, .git/worktrees/orig/gitdir >expect &&
+	mv orig moved &&
+	git -C moved worktree repair >out 2>err &&
+	test_cmp expect .git/worktrees/orig/gitdir &&
+	test_i18ngrep "gitdir incorrect" out &&
+	test_must_be_empty err
+'
+
+test_expect_success 'unable to repair gitdir (implicit) from main worktree' '
+	test_when_finished "rm -rf orig moved && git worktree prune" &&
+	git worktree add --detach orig &&
+	cat .git/worktrees/orig/gitdir >expect &&
+	mv orig moved &&
+	git worktree repair >out 2>err &&
+	test_cmp expect .git/worktrees/orig/gitdir &&
+	test_must_be_empty out &&
+	test_must_be_empty err
+'
+
+test_expect_success 'repair multiple gitdir files' '
+	test_when_finished "rm -rf orig1 orig2 moved1 moved2 &&
+		git worktree prune" &&
+	git worktree add --detach orig1 &&
+	git worktree add --detach orig2 &&
+	sed s,orig1/\.git$,moved1/.git, .git/worktrees/orig1/gitdir >expect1 &&
+	sed s,orig2/\.git$,moved2/.git, .git/worktrees/orig2/gitdir >expect2 &&
+	mv orig1 moved1 &&
+	mv orig2 moved2 &&
+	git worktree repair moved1 moved2 >out 2>err &&
+	test_cmp expect1 .git/worktrees/orig1/gitdir &&
+	test_cmp expect2 .git/worktrees/orig2/gitdir &&
+	test_i18ngrep "gitdir incorrect:.*orig1/gitdir$" out &&
+	test_i18ngrep "gitdir incorrect:.*orig2/gitdir$" out &&
+	test_must_be_empty err
+'
+
 test_done