Hi Peff,
On Fri, 9 Nov 2018, Jeff King wrote:
> On Fri, Nov 09, 2018 at 01:34:17AM -0800, Johannes Schindelin via GitGitGadget wrote:
>
> > diff --git a/builtin/rebase.c b/builtin/rebase.c
> > index 0ee06aa363..6f6d7de156 100644
> > --- a/builtin/rebase.c
> > +++ b/builtin/rebase.c
> > @@ -569,16 +569,13 @@ static int reset_head(struct object_id *oid, const char *action,
> > }
> >
> > if (!fill_tree_descriptor(&desc, oid)) {
> > - error(_("failed to find tree of %s"), oid_to_hex(oid));
> > - rollback_lock_file(&lock);
> > - free((void *)desc.buffer);
> > - return -1;
> > + ret = error(_("failed to find tree of %s"), oid_to_hex(oid));
> > + goto leave_reset_head;
> > }
>
> If fill_tree_descriptor() fails, what is left in desc.buffer? Looking at
> the implementation, I think it's always NULL or a valid buffer. But I
> think all code paths actually die() unless we pass a NULL oid (and in
> that case desc.buffer would be NULL, too).
>
> So I think the original here that calls free() doesn't ever do anything
> but it did not hurt. After your patch, the leave_reset_head code would
> continue to call free(), and that's OK.
Right, that was my thinking, too.
> There are a few earlier conditionals in reset_head() that do only
> rollback_lock_file() that could similarly be converted to use the goto.
> But they would need desc.buffer to be initialized to NULL. I could go
> either way on converting them or not.
Whoops. I should have checked more carefully?
> > @@ -586,10 +583,9 @@ static int reset_head(struct object_id *oid, const char *action,
> >
> > if (write_locked_index(the_repository->index, &lock, COMMIT_LOCK) < 0)
> > ret = error(_("could not write index"));
> > - free((void *)desc.buffer);
> >
> > if (ret)
> > - return ret;
> > + goto leave_reset_head;
> >
> > reflog_action = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
> > strbuf_addf(&msg, "%s: ", reflog_action ? reflog_action : "rebase");
> > @@ -622,7 +618,10 @@ static int reset_head(struct object_id *oid, const char *action,
> > UPDATE_REFS_MSG_ON_ERR);
> > }
> >
> > +leave_reset_head:
> > strbuf_release(&msg);
> > + rollback_lock_file(&lock);
> > + free((void *)desc.buffer);
> > return ret;
>
> We get here on success, too. So we may call rollback_lock_file() on an
> already-committed lock. This is explicitly documented as a no-op by the
> lock code, so that's OK.
Indeed. I did not check the documentation, but the code, and came to the
same conclusion.
> So overall looks good to me.
Thanks!
Dscho
