"git checkout --to" sets up a new working directory with a .git file
pointing to $GIT_DIR/repos/<id>. It then executes "git checkout" again
on the new worktree with the same arguments except "--to" is taken
out. The second checkout execution, which is not contaminated with any
info from the current repository, will actually check out and
everything that normal "git checkout" does.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
Documentation/git-checkout.txt | 34 +++++++++++++
Documentation/gitrepository-layout.txt | 3 ++
builtin/checkout.c | 93 +++++++++++++++++++++++++++++++++-
t/t2025-checkout-to.sh (new +x) | 39 ++++++++++++++
4 files changed, 167 insertions(+), 2 deletions(-)
create mode 100755 t/t2025-checkout-to.sh
diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 33ad2ad..fcf73b2 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -225,6 +225,13 @@ This means that you can use `git checkout -p` to selectively discard
edits from your current working tree. See the ``Interactive Mode''
section of linkgit:git-add[1] to learn how to operate the `--patch` mode.
+--to=<path>::
+ Check out a new branch in a separate working directory at
+ `<path>`. A new working directory is linked to the current
+ repository, sharing everything except working directory
+ specific files such as HEAD, index... See "MULTIPLE CHECKOUT
+ MODE" section for more information.
+
<branch>::
Branch to checkout; if it refers to a branch (i.e., a name that,
when prepended with "refs/heads/", is a valid ref), then that
@@ -388,6 +395,33 @@ $ git reflog -2 HEAD # or
$ git log -g -2 HEAD
------------
+MULTIPLE CHECKOUT MODE
+-------------------------------
+Normally a working directory is attached to repository. When "git
+checkout --to" is used, a new working directory is attached to the
+current repository. This new working directory is called "linked
+checkout" as compared to the "main checkout" prepared by "git init" or
+"git clone". A repository has one main checkout and zero or more
+linked checkouts.
+
+All checkouts share the same repository. Linked checkouts see the
+repository a bit different from the main checkout. When the checkout
+"new" reads the path $GIT_DIR/HEAD for example, the actual path
+returned could be $GIT_DIR/repos/new/HEAD. This ensures checkouts
+won't step on each other.
+
+Each linked checkout has a private space in $GIT_DIR/repos, usually
+named after the base name of the working directory with a number added
+to make it unique. The linked checkout's $GIT_DIR points to this
+private space while $GIT_COMMON_DIR points to the main checkout's
+$GIT_DIR. These settings are done by "git checkout --to".
+
+Because in this mode $GIT_DIR becomes a lightweight virtual file
+system where a path could be rewritten to some place else, accessing
+$GIT_DIR from scripts should use `git rev-parse --git-path` to resolve
+a path instead of using it directly unless the path is known to be
+private to the working directory.
+
EXAMPLES
--------
diff --git a/Documentation/gitrepository-layout.txt b/Documentation/gitrepository-layout.txt
index 9bfe0f1..495a937 100644
--- a/Documentation/gitrepository-layout.txt
+++ b/Documentation/gitrepository-layout.txt
@@ -218,6 +218,9 @@ commondir::
modules::
Contains the git-repositories of the submodules.
+repos::
+ Contains worktree specific information of linked checkouts.
+
SEE ALSO
--------
linkgit:git-init[1],
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 0570e41..2b856a6 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -48,6 +48,10 @@ struct checkout_opts {
const char *prefix;
struct pathspec pathspec;
struct tree *source_tree;
+
+ const char *new_worktree;
+ const char **saved_argv;
+ int new_worktree_mode;
};
static int post_checkout_hook(struct commit *old, struct commit *new,
@@ -250,6 +254,9 @@ static int checkout_paths(const struct checkout_opts *opts,
die(_("Cannot update paths and switch to branch '%s' at the same time."),
opts->new_branch);
+ if (opts->new_worktree)
+ die(_("'%s' cannot be used with updating paths"), "--to");
+
if (opts->patch_mode)
return run_add_interactive(revision, "--patch=checkout",
&opts->pathspec);
@@ -486,7 +493,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
topts.dir->flags |= DIR_SHOW_IGNORED;
setup_standard_excludes(topts.dir);
}
- tree = parse_tree_indirect(old->commit ?
+ tree = parse_tree_indirect(old->commit && !opts->new_worktree_mode ?
old->commit->object.sha1 :
EMPTY_TREE_SHA1_BIN);
init_tree_desc(&trees[0], tree->buffer, tree->size);
@@ -796,7 +803,8 @@ static int switch_branches(const struct checkout_opts *opts,
return ret;
}
- if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
+ if (!opts->quiet && !old.path && old.commit &&
+ new->commit != old.commit && !opts->new_worktree_mode)
orphaned_commit_warning(old.commit, new->commit);
update_refs_for_switch(opts, &old, new);
@@ -806,6 +814,74 @@ static int switch_branches(const struct checkout_opts *opts,
return ret || writeout_error;
}
+static int prepare_linked_checkout(const struct checkout_opts *opts,
+ struct branch_info *new)
+{
+ struct strbuf sb_git = STRBUF_INIT, sb_repo = STRBUF_INIT;
+ struct strbuf sb = STRBUF_INIT;
+ const char *path = opts->new_worktree;
+ struct stat st;
+ const char *name;
+ struct child_process cp;
+ int counter = 0, len;
+
+ if (!new->commit)
+ die(_("no branch specified"));
+
+ len = strlen(path);
+ if (!len || is_dir_sep(path[len - 1]))
+ die(_("'--to' argument '%s' cannot end with a slash"), path);
+
+ for (name = path + len - 1; name > path; name--)
+ if (is_dir_sep(*name)) {
+ name++;
+ break;
+ }
+ strbuf_addstr(&sb_repo, git_path("repos/%s", name));
+ len = sb_repo.len;
+ if (safe_create_leading_directories_const(sb_repo.buf))
+ die_errno(_("could not create leading directories of '%s'"),
+ sb_repo.buf);
+ while (!stat(sb_repo.buf, &st)) {
+ counter++;
+ strbuf_setlen(&sb_repo, len);
+ strbuf_addf(&sb_repo, "%d", counter);
+ }
+ name = sb_repo.buf + len - strlen(name);
+ if (mkdir(sb_repo.buf, 0777))
+ die_errno(_("could not create directory of '%s'"), sb_repo.buf);
+
+ strbuf_addf(&sb_git, "%s/.git", path);
+ if (safe_create_leading_directories_const(sb_git.buf))
+ die_errno(_("could not create leading directories of '%s'"),
+ sb_git.buf);
+
+ write_file(sb_git.buf, 1, "gitdir: %s/repos/%s\n",
+ real_path(get_git_dir()), name);
+ /*
+ * This is to keep resolve_ref() happy. We need a valid HEAD
+ * or is_git_directory() will reject the directory. Any valid
+ * value would do because this value will be ignored and
+ * replaced at the next (real) checkout.
+ */
+ strbuf_addf(&sb, "%s/HEAD", sb_repo.buf);
+ write_file(sb.buf, 1, "%s\n", sha1_to_hex(new->commit->object.sha1));
+ strbuf_reset(&sb);
+ strbuf_addf(&sb, "%s/commondir", sb_repo.buf);
+ write_file(sb.buf, 1, "../..\n");
+
+ if (!opts->quiet)
+ fprintf_ln(stderr, _("Enter %s (identifier %s)"), path, name);
+
+ setenv("GIT_CHECKOUT_NEW_WORKTREE", "1", 1);
+ setenv(GIT_DIR_ENVIRONMENT, sb_git.buf, 1);
+ setenv(GIT_WORK_TREE_ENVIRONMENT, path, 1);
+ memset(&cp, 0, sizeof(cp));
+ cp.git_cmd = 1;
+ cp.argv = opts->saved_argv;
+ return run_command(&cp);
+}
+
static int git_checkout_config(const char *var, const char *value, void *cb)
{
if (!strcmp(var, "diff.ignoresubmodules")) {
@@ -1067,6 +1143,9 @@ static int checkout_branch(struct checkout_opts *opts,
die(_("Cannot switch branch to a non-commit '%s'"),
new->name);
+ if (opts->new_worktree)
+ return prepare_linked_checkout(opts, new);
+
if (!new->commit && opts->new_branch) {
unsigned char rev[20];
int flag;
@@ -1109,6 +1188,8 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
N_("do not limit pathspecs to sparse entries only")),
OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
N_("second guess 'git checkout no-such-branch'")),
+ OPT_STRING(0, "to", &opts.new_worktree, N_("path"),
+ N_("check a branch out in a separate working directory")),
OPT_END(),
};
@@ -1117,6 +1198,9 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
opts.overwrite_ignore = 1;
opts.prefix = prefix;
+ opts.saved_argv = xmalloc(sizeof(const char *) * (argc + 2));
+ memcpy(opts.saved_argv, argv, sizeof(const char *) * (argc + 1));
+
gitmodules_config();
git_config(git_checkout_config, &opts);
@@ -1125,6 +1209,11 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
argc = parse_options(argc, argv, prefix, options, checkout_usage,
PARSE_OPT_KEEP_DASHDASH);
+ /* recursive execution from checkout_new_worktree() */
+ opts.new_worktree_mode = getenv("GIT_CHECKOUT_NEW_WORKTREE") != NULL;
+ if (opts.new_worktree_mode)
+ opts.new_worktree = NULL;
+
if (conflict_style) {
opts.merge = 1; /* implied */
git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
diff --git a/t/t2025-checkout-to.sh b/t/t2025-checkout-to.sh
new file mode 100755
index 0000000..76eae4a
--- /dev/null
+++ b/t/t2025-checkout-to.sh
@@ -0,0 +1,39 @@
+#!/bin/sh
+
+test_description='test git checkout --to'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+ test_commit init
+'
+
+test_expect_success 'checkout --to not updating paths' '
+ test_must_fail git checkout --to -- init.t
+'
+
+test_expect_success 'checkout --to a new worktree' '
+ git checkout --to here master &&
+ (
+ cd here &&
+ test_cmp ../init.t init.t &&
+ git symbolic-ref HEAD >actual &&
+ echo refs/heads/master >expect &&
+ test_cmp expect actual &&
+ git fsck
+ )
+'
+
+test_expect_success 'checkout --to a new worktree creating new branch' '
+ git checkout --to there -b newmaster master &&
+ (
+ cd there &&
+ test_cmp ../init.t init.t &&
+ git symbolic-ref HEAD >actual &&
+ echo refs/heads/newmaster >expect &&
+ test_cmp expect actual &&
+ git fsck
+ )
+'
+
+test_done
--
1.8.5.2.240.g8478abd
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