Fix block_open handling in deflate_quick()

The attached test fails with "inflate() failed", because the deflate
stream that it produces ends up being corrupted. Bisect points to the
commit e7bb6db09a18 ("Replace hash_bits, hash_size and hash_mask with
defines."), but it's most likely a coincidence.

In any case, the reason is that if we happen to simultaneously exhaust
all the buffers (in, out and bi), we return finish_started without
writing the end of block symbol, which will never happen afterwards.

Fix by adding another check to the tricky condition: if we are in the
middle of a block, return need_more instead of finish_started.

1 files changed, 1 insertions, 1 deletions

diff --git a/deflate_quick.c b/deflate_quick.c
index d749b3a..b439743 100644
--- a/deflate_quick.c
+++ b/deflate_quick.c
@@ -65,7 +65,7 @@ Z_INTERNAL block_state deflate_quick(deflate_state *s, int flush) {
         if (UNLIKELY(s->pending + ((BIT_BUF_SIZE + 7) >> 3) >= s->pending_buf_size)) {
             flush_pending(s->strm);
             if (s->strm->avail_out == 0) {
-                return (last && s->strm->avail_in == 0 && s->bi_valid == 0) ? finish_started : need_more;
+                return (last && s->strm->avail_in == 0 && s->bi_valid == 0 && s->block_open == 0) ? finish_started : need_more;
             }
         }