Re: [PATCH] disallow branch names that start with a hyphen

[Junio C Hamano <gitster@pobox.com>]

Clemens Buchacher <drizzd@aon.at> writes:

> On Sun, Aug 22, 2010 at 02:20:17PM -0700, Junio C Hamano wrote:
>> 
>> forbid "checkout -b" and "branch" from creating such a branch.
>
> Sounds good to me. I will have limited access to email this week.
> I'll revisit this when I am back.

Heh, it turns out that we have a perfect place to hook this into.

-- >8 --
Subject: disallow branch names that start with a hyphen

The current command line parser overly lax in places and allows a branch
whose name begins with a hyphen e.g. "-foo" to be created, but the
parseopt infrastructure in general do not like to parse anything that
begin with a dash as a short-hand refname.  "git checkout -foo" won't
work, nor "git branch -d -foo" (even though "git branch -d -- -foo" works,
it does so by mistake; we should not be taking anything but pathspecs
after double-dash).

All the codepath that creates a new branch ref, including the destination
of "branch -m src dst", use strbuf_check_branch_ref() to validate if the
given name is suitable as a branch name.  Tighten it to disallow such a
name.

You can still get rid of historical mistake with

  $ git update-ref -d refs/heads/-foo

and third-party Porcelains are free to keep using update-ref to create
refs with path component that begins with "-".

Issue originally raised by Clemens Buchacher.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

diff --git a/strbuf.c b/strbuf.c
index bc3a080..65b4cf4 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -399,6 +399,8 @@ int strbuf_branchname(struct strbuf *sb, const char *name)
 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
 {
 	strbuf_branchname(sb, name);
+	if (name[0] == '-')
+		return CHECK_REF_FORMAT_ERROR;
 	strbuf_splice(sb, 0, 0, "refs/heads/", 11);
 	return check_ref_format(sb->buf);
 }