[PATCH v2 6/6] worktree: new command to fix up worktree's info after moving

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

This is a low-level command that can be used to correct worktree
information after a worktree is moved. The idea is like 'index refresh'.
In future we may do "worktree refresh" automatically to keep it from
being pruned.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/git-worktree.txt |  8 +++++++-
 builtin/worktree.c             | 18 ++++++++++++++++++
 t/t1501-worktree.sh            |  9 +++++++++
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 62c76c1..306aeec 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -12,6 +12,7 @@ SYNOPSIS
 'git worktree add' [-f] [--detach] [-b <new-branch>] <path> [<branch>]
 'git worktree prune' [-n] [-v] [--expire <expire>]
 'git worktree list' [--porcelain]
+'git worktree refresh'
 
 DESCRIPTION
 -----------
@@ -65,6 +66,11 @@ each of the linked worktrees.  The output details include if the worktree is
 bare, the revision currently checked out, and the branch currently checked out
 (or 'detached HEAD' if none).
 
+refresh::
+
+This command is required to update worktree's information after it's moved.
+Executed from inside the moved worktree.
+
 OPTIONS
 -------
 
@@ -140,7 +146,7 @@ in the entry's directory. For example, if a linked working tree is moved
 to `/newpath/test-next` and its `.git` file points to
 `/path/main/.git/worktrees/test-next`, then update
 `/path/main/.git/worktrees/test-next/gitdir` to reference `/newpath/test-next`
-instead.
+instead. Alternatively you can run "git worktree refresh".
 
 To prevent a $GIT_DIR/worktrees entry from being pruned (which
 can be useful in some situations, such as when the
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 475b958..0183ce0 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -445,6 +445,22 @@ static int list(int ac, const char **av, const char *prefix)
 	return 0;
 }
 
+static int refresh(int ac, const char **av, const char *prefix)
+{
+	const char *gitdir;
+
+	if (ac != 1)
+		die(_("Arguments not expected"));
+
+	gitdir = git_pathdup("gitdir");
+	if (access(gitdir, F_OK))
+		return 0;
+	if (!startup_info->first_gitfile)
+		die("BUG: .git file's location not found");
+	write_file(gitdir, "%s", startup_info->first_gitfile);
+	return 0;
+}
+
 int cmd_worktree(int ac, const char **av, const char *prefix)
 {
 	struct option options[] = {
@@ -459,5 +475,7 @@ int cmd_worktree(int ac, const char **av, const char *prefix)
 		return prune(ac - 1, av + 1, prefix);
 	if (!strcmp(av[1], "list"))
 		return list(ac - 1, av + 1, prefix);
+	if (!strcmp(av[1], "refresh"))
+		return refresh(ac - 1, av + 1, prefix);
 	usage_with_options(worktree_usage, options);
 }
diff --git a/t/t1501-worktree.sh b/t/t1501-worktree.sh
index cc5b870..821831b 100755
--- a/t/t1501-worktree.sh
+++ b/t/t1501-worktree.sh
@@ -423,4 +423,13 @@ test_expect_success '$GIT_WORK_TREE overrides $GIT_DIR/common' '
 	)
 '
 
+test_expect_success 'worktree refresh corrects gitdir file' '
+	git worktree add test-refresh &&
+	P=repo.git/worktrees/test-refresh/gitdir &&
+	echo corrupt >$P &&
+	git -C test-refresh worktree refresh &&
+	echo "$TRASH_DIRECTORY/test-refresh/.git" >expected &&
+	test_cmp expected $P
+'
+
 test_done
-- 
2.7.0.96.g5373197