On Thu, Oct 17, 2019 at 04:03:00PM +0900, Junio C Hamano wrote: > Jeff King <peff@xxxxxxxx> writes: > > >> Hmm, I am kind of surprised that the decoding side allowed such a > >> padding. > > > > IIRC, the "padding" is just a sequence of 0-length-plus-continuation-bit > > varint bytes. And for some reason it worked for the size but not for the > > delta offset value. > > I think the reason is because they use different varint definition. > > The encoding used in builtin/pack-objects.c::write_no_reuse_object() > is for offsets, and it came much later and with an improvement over > the encoding used for delta size in diff-delta.c::create_delta(). > The more recent encoding does not allow padding (when I compare the > decoders for these two encodings, I notice there is +1 for each > 7-bit iteration; this essentially declares that a byte with "not the > final byte" bit set with all other bits clear does not mean 0 but it > means 1, which breaks the idea of padding to encode filler zero > bits). Yeah, that sounds right. I think the "old" one is actually the pack size header in unpack_object_header_buffer(), not the delta size header. At any rate, it seems like a terrible idea, so I'll be glad to see the code dropped. :) -Peff
