[PULL 1/2] util/ioc.c: try to reassure Coverity about qemu_iovec_init_extended

[Stefan Hajnoczi <stefanha@redhat.com>]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Make it more obvious, that filling qiov corresponds to qiov allocation,
which in turn corresponds to total_niov calculation, based on mid_niov
(not mid_len). Still add an assertion to show that there should be no
difference.

Reported-by: Coverity (CID 1405302)
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190910090310.14032-1-vsementsov@virtuozzo.com
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20190910090310.14032-1-vsementsov@virtuozzo.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 util/iov.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/util/iov.c b/util/iov.c
index 5059e10431..a4689ff3c9 100644
--- a/util/iov.c
+++ b/util/iov.c
@@ -446,7 +446,8 @@ void qemu_iovec_init_extended(
         p++;
     }
 
-    if (mid_len) {
+    assert(!mid_niov == !mid_len);
+    if (mid_niov) {
         memcpy(p, mid_iov, mid_niov * sizeof(*p));
         p[0].iov_base = (uint8_t *)p[0].iov_base + mid_head;
         p[0].iov_len -= mid_head;
-- 
2.21.0