[using the updated nbd list email]
On 02/14/2018 08:35 AM, Vladimir Sementsov-Ogievskiy wrote:
Hi all.
Just note: looks like we allow zero-sized metadata context name. Is
it ok?
*
|NBD_REP_META_CONTEXT| (4)
A description of a metadata context. Data:
o 32 bits, NBD metadata context ID.
o String, name of the metadata context. This is not required to be
a human-readable string, but it MUST be valid UTF-8 data.
No; elsewhere we state:
Metadata contexts are identified by their names. The name MUST
consist of a namespace, followed by a colon, followed by a leaf-name.
The namespace must consist entirely of printable non-whitespace UTF-8
characters other than colons, and be non-empty. The entire name
(namespace, colon, and leaf-name) MUST follow the restrictions for
strings as laid out earlier in this document.
Namespaces MUST be consist of one of the following:
base, for metadata contexts defined by this document;
nbd-server, for metadata contexts defined by the implementation
that accompanies this document (none currently);
x-*, where * can be replaced by an arbitrary string not
containing colons, for local experiments. This SHOULD NOT be used by
metadata contexts that are expected to be widely used.
A third-party namespace from the list below.
So a name must be at least 2 bytes (for a one-byte namespace, if
someone ever registers one - and supposing that namespace has
zero-byte leaf names), but will more commonly be even longer.