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[PATCH 3/3] Teach "git branch" about --new-workdir

From
Johannes Schindelin <johannes.schindelin@gmx.de>
Date
Jul 22, 2007, 18:56 UTC
Message-ID
<Pine.LNX.4.64.0707221956210.14781@racer.site>

Inspired by contrib/workdir/git-new-workdir, the flag --new-workdir (or its shortcut, -n) can be used to create a new working directory for the newly created branch. All information, except which branch is checked out (and therefore also the index), will be symlinked from the current repository.

Example:
	$ git branch -n ~/my-new-topic xy-problem

will create a branch called "xy-problem", which is initially identical to the current branch, and check out the new branch in ~/my-new-topic/. You will be able to cherry-pick from, log and diff with the branch "xy-problem" in the current repository, since most of the metadata is shared.

Conversely, you can access all the branches in the current repository from ~/my-new-topic/, too.

A word of warning: switching to _same_ branch that is checked out in the other repository is asking for trouble. You are really working not only on the same object database, but also the same (i.e. not copied) refs namespace.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
	IMHO this is a better syntax than what is in contrib/, and "git
	branch" is probably the right place for such a thing, from a
	user's perspective.
 Documentation/git-branch.txt |    7 +++-
 builtin-branch.c             |   79 +++++++++++++++++++++++++++++++++++++++--
 t/t3200-branch.sh            |   11 ++++++
 3 files changed, 92 insertions(+), 5 deletions(-)
diff --git a/Documentation/git-branch.txt b/Documentation/git-branch.txt
index bc6aa88..a05c795 100644
--- a/Documentation/git-branch.txt
+++ b/Documentation/git-branch.txt
@@ -10,7 +10,8 @@ SYNOPSIS
 [verse]
 'git-branch' [--color | --no-color] [-r | -a]
 	   [-v [--abbrev=<length> | --no-abbrev]]
-'git-branch' [--track | --no-track] [-l] [-f] <branchname> [<start-point>]
+'git-branch' [--track | --no-track] [-l] [-f] <branchname>
+	   [-n <dir> | --new-workdir <dir>] [<start-point>]
 'git-branch' (-m | -M) [<oldbranch>] <newbranch>
 'git-branch' (-d | -D) [-r] <branchname>...
 
@@ -91,6 +92,10 @@ OPTIONS
 --no-abbrev::
 	Display the full sha1s in output listing rather than abbreviating them.
 
+-n\|--new-workdir <dir>::
+	Set up a new working directory which shares all information with the
+	current repository, except which branch is checked out.
+
 <branchname>::
 	The name of the branch to create or delete.
 	The new branch name must pass all checks defined by
diff --git a/builtin-branch.c b/builtin-branch.c
index 5f5c182..cba5fac 100644
--- a/builtin-branch.c
+++ b/builtin-branch.c
@@ -11,9 +11,10 @@
 #include "commit.h"
 #include "builtin.h"
 #include "remote.h"
+#include "unpack-trees.h"
 
 static const char builtin_branch_usage[] =
-  "git-branch [-r] (-d | -D) <branchname> | [--track | --no-track] [-l] [-f] <branchname> [<start-point>] | (-m | -M) [<oldbranch>] <newbranch> | [--color | --no-color] [-r | -a] [-v [--abbrev=<length> | --no-abbrev]]";
+  "git-branch [-r] (-d | -D) <branchname> | [--track | --no-track] [-l] [-f] [-n <dir> | --new-workdir <dir>] <branchname> [<start-point>] | (-m | -M) [<oldbranch>] <newbranch> | [--color | --no-color] [-r | -a] [-v [--abbrev=<length> | --no-abbrev]]";
 
 #define REF_UNKNOWN_TYPE    0x00
 #define REF_LOCAL_BRANCH    0x01
@@ -500,6 +501,67 @@ static void rename_branch(const char *oldname, const char *newname, int force)
 		die("Branch is renamed, but update of config-file failed");
 }
 
+static struct lock_file lockfile;
+
+/* This function free()s path */
+static int create_new_workdir(char *path, const char *branch_name)
+{
+	static const char *links[] = {
+		"config", "refs", "logs/refs", "objects", "info", "hooks",
+		"packed-refs", "remotes", "rr-cache", NULL
+	};
+	const char *git_dir = get_git_dir(), *absolute;
+	struct stat st;
+	unsigned char sha1[20];
+	char *ref;
+	struct object *object;
+	struct unpack_trees_options opts;
+	struct object_list trees;
+	int i, fd;
+
+	if (!has_symlinks)
+		return error("New workdir not possible without symlinks");
+	/* make sure that GIT_DIR is an absolute path */
+	if ((absolute = make_absolute_path(git_dir)) != git_dir &&
+			setup_new_git_dir(absolute))
+		return 1;
+	if (!lstat(git_path("config"), &st) && S_ISLNK(st.st_mode))
+		return error("Will not create a workdir from a workdir");
+	if (safe_create_leading_directories(path) ||
+			mkdir(path, 0777) || chdir(path))
+		return error("Could not create '%s'", path);
+	if (mkdir(DEFAULT_GIT_DIR_ENVIRONMENT, 0777) ||
+			chdir(DEFAULT_GIT_DIR_ENVIRONMENT) ||
+			mkdir("logs", 0777))
+		return error("Could not set up '%s/%s'",
+				path, DEFAULT_GIT_DIR_ENVIRONMENT);
+	for (i = 0; links[i]; i++)
+		if (symlink(git_path(links[i]), links[i]))
+			return error("Could not link '%s'", links[i]);
+	if (chdir("..") || setup_new_git_dir(DEFAULT_GIT_DIR_ENVIRONMENT))
+		return error("Error setting up new workdir");
+	fd = hold_locked_index(&lockfile, 1);
+	if (fd < 0)
+		return error("Could not lock index");
+	if (dwim_ref(branch_name, strlen(branch_name), sha1, &ref) != 1 ||
+			create_symref("HEAD", ref, "new workdir") ||
+			!(object = parse_object(sha1)) ||
+			object->type != OBJ_COMMIT)
+		return error("Could not checkout HEAD");
+	free(ref);
+	trees.item = &((struct commit *)object)->tree->object;
+	trees.next = NULL;
+
+	memset(&opts, 0, sizeof(opts));
+	opts.update = 1;
+	opts.merge = 1;
+	opts.head_idx = 1;
+	opts.fn = oneway_merge;
+	return unpack_trees(&trees, &opts) ||
+		write_cache(fd, active_cache, active_nr) ||
+		close(fd) || commit_locked_index(&lockfile);
+}
+
 int cmd_branch(int argc, const char **argv, const char *prefix)
 {
 	int delete = 0, force_delete = 0, force_create = 0;
@@ -507,6 +569,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 	int verbose = 0, abbrev = DEFAULT_ABBREV, detached = 0;
 	int reflog = 0, track;
 	int kinds = REF_LOCAL_BRANCH;
+	char *new_workdir = NULL;
 	int i;
 
 	git_config(git_branch_config);
@@ -587,11 +650,17 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 			branch_use_color = 0;
 			continue;
 		}
+		if (!strcmp(arg, "--new-workdir") || !strcmp(arg, "-n")) {
+			if (++i >= argc)
+				usage(builtin_branch_usage);
+			new_workdir = xstrdup(argv[i]);
+			continue;
+		}
 		usage(builtin_branch_usage);
 	}
 
 	if ((delete && rename) || (delete && force_create) ||
-	    (rename && force_create))
+	    (rename && force_create) || (new_workdir && (delete || rename)))
 		usage(builtin_branch_usage);
 
 	head = resolve_ref("HEAD", head_sha1, 0, NULL);
@@ -615,10 +684,12 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		rename_branch(head, argv[i], force_rename);
 	else if (rename && (i == argc - 2))
 		rename_branch(argv[i], argv[i + 1], force_rename);
-	else if (i == argc - 1 || i == argc - 2)
+	else if (i == argc - 1 || i == argc - 2) {
 		create_branch(argv[i], (i == argc - 2) ? argv[i+1] : head,
 			      force_create, reflog, track);
-	else
+		if (new_workdir)
+			return create_new_workdir(new_workdir, argv[i]);
+	} else
 		usage(builtin_branch_usage);
 
 	return 0;
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index ef1eeb7..d9ec82a 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -202,4 +202,15 @@ test_expect_success \
 	 test -f .git/logs/refs/heads/g/h/i &&
 	 diff expect .git/logs/refs/heads/g/h/i'
 
+test_expect_success 'create new workdir' '
+	git branch -n new-workdir forked &&
+	test -d new-workdir &&
+	(cd new-workdir &&
+	 test $HEAD = $(git rev-parse HEAD) &&
+	 test refs/heads/forked = $(git symbolic-ref HEAD) &&
+	 git fsck &&
+	 git diff-files --quiet &&
+	 git diff-index --quiet --cached HEAD)
+'
+
 test_done

-- 
1.5.3.rc2.29.gc4640f
Next: Daniel Barkalow
Message 1 of 46 in “Teach "git branch" about --new-workdir”
  1. 3/3 Teach "git branch" about --new-workdirJohannes Schindelin, Jul 22, 2007
  2. Daniel BarkalowJul 22, 2007
  3. Johannes SchindelinJul 22, 2007
  4. Julian PhillipsJul 22, 2007
  5. Johannes SchindelinJul 22, 2007
  6. Julian PhillipsJul 22, 2007
  7. Johannes SchindelinJul 22, 2007
  8. Julian PhillipsJul 22, 2007
  9. Jakub NarebskiJul 22, 2007
  10. Johannes SchindelinJul 22, 2007
  11. Johannes SchindelinJul 22, 2007
  12. Shawn O. PearceJul 23, 2007
  13. Junio C HamanoJul 23, 2007
  14. Shawn O. PearceJul 23, 2007
  15. Shawn O. PearceJul 23, 2007
  16. Johannes SchindelinJul 23, 2007
  17. Johannes SchindelinJul 23, 2007
  18. Marius Storm-OlsenJul 24, 2007
  19. Johannes SchindelinJul 24, 2007
  20. Junio C HamanoJul 24, 2007
  21. Johannes SchindelinJul 24, 2007
  22. Marius Storm-OlsenJul 24, 2007
  23. Julian PhillipsJul 24, 2007
  24. Marius Storm-OlsenJul 24, 2007
  25. Johannes SchindelinJul 24, 2007
  26. Josef WeidendorferJul 24, 2007
  27. Johannes SchindelinJul 24, 2007
  28. Josef WeidendorferJul 24, 2007
  29. Jakub NarebskiJul 25, 2007
  30. Johannes SchindelinJul 24, 2007
  31. Marius Storm-OlsenJul 24, 2007
  32. Marius Storm-OlsenJul 24, 2007
  33. Johannes SchindelinJul 24, 2007
  34. Marius Storm-OlsenJul 24, 2007
  35. Johannes SchindelinJul 24, 2007
  36. Marius Storm-OlsenJul 24, 2007
  37. Alex RiesenJul 24, 2007
  38. Marius Storm-OlsenJul 25, 2007
  39. Johannes SchindelinJul 25, 2007
  40. Steven GrimmJul 25, 2007
  41. Andy ParkinsJul 25, 2007
  42. Marius Storm-OlsenJul 25, 2007
  43. Johannes SchindelinJul 25, 2007
  44. Linus TorvaldsJul 25, 2007
  45. Christian MICHONJul 26, 2007
  46. Julian PhillipsJul 23, 2007

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