Prevent force-updating of the current branch

"git branch -M <foo> <current-branch>" allows updating the current branch
which HEAD points, without the necessary house-keeping that git reset
normally does to make this operation sensible. It also leaves the reflog
in a confusing state (you would be warned when trying to read it).

"git checkout -B <current branch> <foo>" is also partly vulnerable to this
bug; due to inconsistent pre-flight checks it would perform half of its
task and then abort just before rewriting the branch. Again this
manifested itself as the index file getting out-of-sync with HEAD.

"git branch -f" already guarded against this problem, and aborts with
a fatal error.

Update "git branch -M", "git checkout -B" and "git branch -f" to share the
same check before allowing a branch to be created. These prevent you from
updating the current branch.

We considered suggesting the use of "git reset" in the failure message
but concluded that it was not possible to discern what the user was
actually trying to do.

Signed-off-by: Conrad Irwin <conrad.irwin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Conrad Irwin
2011-08-20 14:49:48 -07:00
committed by Junio C Hamano
parent 1be9d84b2e
commit 55c4a67307
6 changed files with 56 additions and 24 deletions

View File

@ -1071,15 +1071,9 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
if (opts.new_branch) {
struct strbuf buf = STRBUF_INIT;
if (strbuf_check_branch_ref(&buf, opts.new_branch))
die(_("git checkout: we do not like '%s' as a branch name."),
opts.new_branch);
if (ref_exists(buf.buf)) {
opts.branch_exists = 1;
if (!opts.new_branch_force)
die(_("git checkout: branch %s already exists"),
opts.new_branch);
}
opts.branch_exists = validate_new_branchname(opts.new_branch, &buf, !!opts.new_branch_force);
strbuf_release(&buf);
}