From 0afbe3e806f48a701188eefd8d7c474cc119df53 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Wed, 31 Oct 2018 01:13:16 -0400 Subject: [PATCH] read_istream_pack_non_delta(): document input handling Twice now we have scratched our heads about why the loose streaming code needs the protection added by 692f0bc7ae (avoid infinite loop in read_istream_loose, 2013-03-25), but the similar code in its pack counterpart does not. The short answer is that use_pack() will die before it lets us run out of bytes. Note that this could mean reading garbage (including the trailing hash) from the packfile in some cases of corruption, but that's OK. zlib will notice and complain (and if not, certainly the end result will not match the object hash we expect). Let's leave a comment this time to document our findings. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- streaming.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/streaming.c b/streaming.c index d1e6b2dce6877c..ac7c7a22f90b73 100644 --- a/streaming.c +++ b/streaming.c @@ -408,6 +408,15 @@ static read_method_decl(pack_non_delta) st->z_state = z_done; break; } + + /* + * Unlike the loose object case, we do not have to worry here + * about running out of input bytes and spinning infinitely. If + * we get Z_BUF_ERROR due to too few input bytes, then we'll + * replenish them in the next use_pack() call when we loop. If + * we truly hit the end of the pack (i.e., because it's corrupt + * or truncated), then use_pack() catches that and will die(). + */ if (status != Z_OK && status != Z_BUF_ERROR) { git_inflate_end(&st->z); st->z_state = z_error;