Re: [PATCH] Teach git-branch howto rename a branch

From: Junio C Hamano <junkio@cox.net>
Date: Nov 28, 2006, 08:49 UTC
Message-ID: <7vzmac3qig.fsf@assigned-by-dhcp.cox.net>
In-Reply-To: <1164679287192-git-send-email-hjemli@gmail.com>

Lars Hjemli <hjemli@gmail.com> writes:

Show 7 quoted lines

> This adds a '--rename' option to git branch. If specified, branch
> creation becomes branch renaming.
>
> With a single branchname, the current branch is renamed and .git/HEAD is
> updated.
>
> With two branchnames, the second name is renamed to the first.

Thanks.

"--rename newname oldname" feels funny, as already mentioned a few times on the list. rename(2) is "rename(old, new)" and mv(1) is "mv old new".

> This seems to do the right thing for both refs and reflogs, but 'make test' 
> probably should be expanded with some evil test-cases to confirm my manual
> testing.

Certainly.  Let's keep discipline to have tests and docs for new
features.
 
+static void rename_branch(const char *oldname, const char *newname, int force)
+{
+	char oldref[PATH_MAX], newref[PATH_MAX];
+	unsigned char sha1[20];
+
+	snprintf(oldref, sizeof oldref, "refs/heads/%s", oldname);
+	if (check_ref_format(oldref))
+		die("Invalid branch name: %s", oldref);

Although "sizeof type" is valid C, we tend to prefer "sizeof(type)". If you use snprintf(), it would make sense to check its return value.

+ if (resolve_ref(newref, sha1, 1, NULL) && !force) + die("A branch named '%s' already exists.\n", newname);

No trailing '\n' is necessary for die().

+ if (!rename_ref(oldref, newref) && !strcmp(oldname, head)) + create_symref("HEAD", newref); +}

Can create_symref() fail?

+int rename_ref(const char *oldref, const char *newref) +{ + unsigned char sha1[20], orig_sha1[20]; + int flag = 0, logmoved = 0; + struct ref_lock *lock; + char msg[PATH_MAX*2 + 100]; + struct stat stat; + int log = !lstat(git_path("logs/%s", oldref), &stat);

This is not wrong per-se, but it made me stop and wonder if we want to error out when we find out "logs/oldref" is a symlink; I do not think we care about it that much, but in that case we may want to say stat() here instead... Just a minor detail.

+ lock = lock_ref_sha1_basic("tmp-renamed-ref", NULL, NULL); + if (!lock) + return error("unable to lock tmp-renamed-ref"); + lock->force_write = 1; + if (write_ref_sha1(lock, orig_sha1, msg)) + return error("unable to save current sha1 in tmp-renamed-ref"); + if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log"))) + return error("unable to move logfile logs/%s to tmp-renamed-log: %s", + oldref, strerror(errno));

I am confused with this code. tmp-renamed-ref is not even a ref, you lock $GIT_DIR/tmp-renamed-ref and call write-ref_sha1() with an uninitialized msg[] buffer to write into a logfile. What is the name of that logfile? $GIT_DIR/log/tmp-renamed-ref???