Michael Haggerty <mhagger@xxxxxxxxxxxx> writes:
> From: David Turner <dturner@xxxxxxxxxxxxxxxx>
>
> Signed-off-by: David Turner <dturner@xxxxxxxxxxxxxxxx>
> Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx>
> Signed-off-by: Michael Haggerty <mhagger@xxxxxxxxxxxx>
> ---
> refs/refs-internal.h | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/refs/refs-internal.h b/refs/refs-internal.h
> index efe5847..d8a2606 100644
> --- a/refs/refs-internal.h
> +++ b/refs/refs-internal.h
> @@ -240,6 +240,11 @@ const char *find_descendant_ref(const char *dirname,
> const struct string_list *extras,
> const struct string_list *skip);
>
> +/*
> + * Check if the new name does not conflict with any existing refs
> + * (other than possibly the old ref). Return 0 if the ref can be
> + * renamed to the new name.
> + */
> int rename_ref_available(const char *oldname, const char *newname);
I do not quite understand the comment. Partly because it is unclear
what "conflict" means here, but I guess it means a D/F conflict that
is explained near verify_refname_available()?
A new name can conflict with an existing, possibly old ref? Are you
referring to this condition?
You are trying to rename "refs/a/b" to "refs/a", which would
conflict, but as long as there is no other ref that share the
prefix "refs/a/", e.g. "refs/a/c", the new name "refs/a" is
available.
I wonder if it is necessary to document that this function is not
meant to protect us from others racing with us. That is, when you
are renaming something to "refs/a", you call this function and it
finds, by calling verify_refname_available(), that the repository
has nothing that conflicts with the name and says "OK", but before
you actually do the rename, somebody may push from sideways to
create "refs/a/b", making the result of an earlier check with this
function invalid.
Or is this to be called only under a lock that protects us from such
a race?
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