On 07/07/2017 09:53 AM, Markus Armbruster wrote: > Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> writes: > >> 07.07.2017 12:00, Markus Armbruster wrote: >>> "Daniel P. Berrange" <berra...@redhat.com> writes: >>> >>>> On Fri, Jul 07, 2017 at 10:05:22AM +0200, Markus Armbruster wrote: >>>>> Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> writes: >>>>> >>>>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> >>>>>> --- >>>>>> block/dirty-bitmap.c | 5 +++++ >>>>>> blockdev.c | 25 +++++++++++++++++++++++++ >>>>>> include/block/dirty-bitmap.h | 1 + >>>>>> include/qemu/hbitmap.h | 8 ++++++++ >>>>>> qapi/block-core.json | 27 +++++++++++++++++++++++++++ >>>>>> tests/Makefile.include | 2 +- >>>>>> util/hbitmap.c | 11 +++++++++++ >>>>>> 7 files changed, 78 insertions(+), 1 deletion(-) >>>>> [...] >>>>>> diff --git a/qapi/block-core.json b/qapi/block-core.json >>>>>> index 5c42cc7790..6ad8585400 100644 >>>>>> --- a/qapi/block-core.json >>>>>> +++ b/qapi/block-core.json >>>>>> @@ -1644,6 +1644,33 @@ >>>>>> 'data': 'BlockDirtyBitmap' } >>>>>> ## >>>>>> +# @BlockDirtyBitmapSha256: >>>>>> +# >>>>>> +# SHA256 hash of dirty bitmap data >>>>>> +# >>>>>> +# @sha256: ASCII representation of SHA256 bitmap hash >>>>> Spell it SHA-256, please. The member name @sha256 can stay. >>>>> >>>>> SHA-256 is 256 binary bits. Please specify how they are represented in >>>>> ASCII. It better be base64 (RFC 4648), because we use that elsewhere. >>>> It is filled later in this patch using qcrypto_hash_digest, so it is just >>>> a hex string representing the hash, not base64. For the latter you can >>>> use qcrypto_hash_base64 >>> I got two points: >>> >>> 1. Whatever encoding we use, it needs to be documented. >>> >>> 2. The fewer binary -> ASCII encodings we use, the better. We already >>> use base64. >> >> >> ASCII format for check sum is more common as it is more readable. It >> is used in the internet to check downloads, it is used by standard >> utility sha256sum. So, it may be better for the monitor. >> >> However, if it is needed, I can make a follow-up patch, it is very >> easy, just s/qcrypto_hash_digest/qcrypto_hash_base64/ in >> util/hbitmap.c. iotest 165 - the only user of the feature - doesn't >> need any changes. > > If the is a standard way to represent SHA-256 in ASCII, use it. > > Whatever you use, document it clearly in the QAPI schema. >
I... should we, though? It's a debug interface for testing only, basically. Couldn't think of a better way to test it, and people demanded tests. How's this for documentation: "The hash will be in an arbitrary format that changes every time you look away from this specification. Any similarity, real or imagined, to a canonical SHA-256 ASCII string is purely coincidental." Basically, I would actually rather go out of my way to obfuscate this command, not document it... Maybe that's wrong-headed of me, but I still maintain that it's not terribly important because I'd rather people never, ever try to use this in production.
