Re: Infinite loop regression in git-fsck in v2.12.0
On Tue, Oct 30, 2018 at 06:56:03PM -0400, Jeff King wrote:
Show 22 quoted lines
> > > while (total_read <= size &&
> > > + stream->avail_in > 0 &&
> > > (status == Z_OK || status == Z_BUF_ERROR)) {
> > > stream->next_out = buf;
> > > stream->avail_out = sizeof(buf);
> >
> > Hmph. If the last round consumed the final input byte and needed
> > output space of N bytes, but only M (< N) bytes of the output space
> > was available, then it would have reduced both avail_in and
> > avail_out down to zero and yielded Z_BUF_ERROR, no? Or would zlib
> > refrain from consuming that final byte (leaving avail_in to at least
> > one) and give us Z_BUF_ERROR in such a case?
>
> Hmm, yeah, good thinking. I think zlib could consume that final byte
> into its internal buffer.
>
> As part of my digging, I looked at how the loose streaming code handles
> this. It checks that when we see Z_BUF_ERROR, we actually did run out of
> output bytes (so if we didn't, then we know it's not the case we
> expected to be looping on).
>
> I have some patches almost ready to send; I'll use that technique.And here they are.
[1/3]: t1450: check large blob in trailing-garbage test
[2/3]: check_stream_sha1(): handle input underflow
[3/3]: cat-file: handle streaming failures consistently
builtin/cat-file.c | 16 ++++++++++++----
sha1-file.c | 3 ++-
t/t1450-fsck.sh | 23 +++++++++++++++++++++--
3 files changed, 35 insertions(+), 7 deletions(-)
-Peff
Jeff King <peff@peff.net>