"git checkout --to" sets up a new working directory with a .git file
pointing to $GIT_DIR/worktrees/<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.
Helped-by: Marc Branchaud <marcnarc@xxxxxxxxxxx>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
Documentation/git-checkout.txt | 46 ++++++++++++++++
Documentation/git.txt | 3 +-
Documentation/gitrepository-layout.txt | 7 +++
builtin/checkout.c | 95 +++++++++++++++++++++++++++++++++-
path.c | 2 +-
t/t2025-checkout-to.sh (new +x) | 63 ++++++++++++++++++++++
6 files changed, 212 insertions(+), 4 deletions(-)
create mode 100755 t/t2025-checkout-to.sh
diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 33ad2ad..c101575 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 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 WORKING
+ TREES" 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 +395,45 @@ $ git reflog -2 HEAD # or
$ git log -g -2 HEAD
------------
+MULTIPLE WORKING TREES
+----------------------
+
+A git repository can support multiple working trees, allowing you to check
+out more than one branch at a time. With `git checkout --to` a new working
+tree is associated with the repository. This new working tree is called a
+"linked working tree" as opposed to the "main working tree" prepared by "git
+init" or "git clone". A repository has one main working tree (if it's not a
+bare repository) and zero or more linked working trees.
+
+Each linked working tree has a private sub-directory in the repository's
+$GIT_DIR/worktrees directory. The private sub-directory's name is usually
+the base name of the linked working tree's path, possibly appended with a
+number to make it unique. For example, when `$GIT_DIR=/path/main/.git` the
+command `git checkout --to /path/other/test-next next` creates the linked
+working tree in `/path/other/test-next` and also creates a
+`$GIT_DIR/worktrees/test-next` directory (or `$GIT_DIR/worktrees/test-next1`
+if `test-next` is already taken).
+
+Within a linked working tree, $GIT_DIR is set to point to this private
+directory (e.g. `/path/main/.git/worktrees/test-next` in the example) and
+$GIT_COMMON_DIR is set to point back to the main working tree's $GIT_DIR
+(e.g. `/path/main/.git`). These settings are made in a `.git` file located at
+the top directory of the linked working tree.
+
+Path resolution via `git rev-parse --git-path` uses either
+$GIT_DIR or $GIT_COMMON_DIR depending on the path. For example, in the
+linked working tree `git rev-parse --git-path HEAD` returns
+`/path/main/.git/worktrees/test-next/HEAD` (not
+`/path/other/test-next/.git/HEAD` or `/path/main/.git/HEAD`) while `git
+rev-parse --git-path refs/heads/master` uses
+$GIT_COMMON_DIR and returns `/path/main/.git/refs/heads/master`,
+since refs are shared across all working trees.
+
+See linkgit:gitrepository-layout[5] for more information. The rule of
+thumb is do not make any assumption about whether a path belongs to
+$GIT_DIR or $GIT_COMMON_DIR when you need to directly access something
+inside $GIT_DIR. Use `git rev-parse --git-path` to get the final path.
+
EXAMPLES
--------
diff --git a/Documentation/git.txt b/Documentation/git.txt
index 176d37c..54c9fb6 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -806,7 +806,8 @@ Git so take care if using Cogito etc.
If this variable is set to a path, non-worktree files that are
normally in $GIT_DIR will be taken from this path
instead. Worktree-specific files such as HEAD or index are
- taken from $GIT_DIR. See linkgit:gitrepository-layout[5] for
+ taken from $GIT_DIR. See linkgit:gitrepository-layout[5] and
+ the section 'MULTIPLE CHECKOUT MODE' in linkgit:checkout[1]
details. This variable has lower precedence than other path
variables such as GIT_INDEX_FILE, GIT_OBJECT_DIRECTORY...
diff --git a/Documentation/gitrepository-layout.txt b/Documentation/gitrepository-layout.txt
index 2dc5667..8228450 100644
--- a/Documentation/gitrepository-layout.txt
+++ b/Documentation/gitrepository-layout.txt
@@ -252,6 +252,13 @@ modules::
directory is ignored if $GIT_COMMON_DIR is set and
"$GIT_COMMON_DIR/modules" will be used instead.
+worktrees::
+ Contains worktree specific information of linked
+ checkouts. Each subdirectory contains the worktree-related
+ part of a linked checkout. This directory is ignored if
+ $GIT_COMMON_DIR is set and "$GIT_COMMON_DIR/worktrees" will be
+ used instead.
+
SEE ALSO
--------
linkgit:git-init[1],
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 220f80e..ad10f99 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,
@@ -249,6 +253,9 @@ 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);
@@ -484,7 +491,7 @@ 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);
@@ -800,7 +807,8 @@ 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);
@@ -810,6 +818,76 @@ 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, *name;
+ struct stat st;
+ struct child_process cp;
+ int counter = 0, len;
+
+ if (!new->commit)
+ die(_("no branch specified"));
+ if (file_exists(path))
+ die(_("'%s' already exists"), path);
+
+ len = strlen(path);
+ while (len && is_dir_sep(path[len - 1]))
+ len--;
+
+ for (name = path + len - 1; name > path; name--)
+ if (is_dir_sep(*name)) {
+ name++;
+ break;
+ }
+ strbuf_addstr(&sb_repo,
+ git_path("worktrees/%.*s", (int)(path + len - name), 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 = strrchr(sb_repo.buf, '/') + 1;
+ 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/worktrees/%s\n",
+ real_path(get_git_common_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")) {
@@ -1071,6 +1149,9 @@ 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;
@@ -1113,6 +1194,8 @@ 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_FILENAME(0, "to", &opts.new_worktree,
+ N_("check a branch out in a separate working directory")),
OPT_END(),
};
@@ -1121,6 +1204,9 @@ 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);
@@ -1129,6 +1215,11 @@ 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/path.c b/path.c
index 94db501..72eca6d 100644
--- a/path.c
+++ b/path.c
@@ -92,7 +92,7 @@ static void replace_dir(struct strbuf *buf, int len, const char *newdir)
static const char *common_list[] = {
"/branches", "/hooks", "/info", "/logs", "/lost-found", "/modules",
- "/objects", "/refs", "/remotes", "/rr-cache", "/svn",
+ "/objects", "/refs", "/remotes", "/worktrees", "/rr-cache", "/svn",
"config", "gc.pid", "packed-refs", "shallow",
NULL
};
diff --git a/t/t2025-checkout-to.sh b/t/t2025-checkout-to.sh
new file mode 100755
index 0000000..4963415
--- /dev/null
+++ b/t/t2025-checkout-to.sh
@@ -0,0 +1,63 @@
+#!/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 an existing worktree' '
+ mkdir existing &&
+ test_must_fail git checkout --detach --to existing master
+'
+
+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 from a subdir' '
+ (
+ mkdir sub &&
+ cd sub &&
+ git checkout --detach --to here master &&
+ cd here &&
+ test_cmp ../../init.t init.t
+ )
+'
+
+test_expect_success 'checkout --to from a linked checkout' '
+ (
+ cd here &&
+ git checkout --to nested-here master &&
+ cd nested-here &&
+ 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
--
2.1.0.rc0.78.gc0d8480
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