curl: Check curl_multi_add_handle()'s return code

If we had done that all along, debugging would have been much simpler.
(Also, I/O errors are better than hangs.)

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190910124136.10565-8-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
(cherry picked from commit c34dc07f9f01cf686e512f939aece744723072cd)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/block/curl.c b/block/curl.c
index af4020371100f92c03f92e39c1d6ce702bd16aa2..7a29b409544765df31a3fe087ae8a63a68469d37 100644 (file)
--- a/block/curl.c
+++ b/block/curl.c
@@ -881,7 +881,13 @@ static void curl_setup_preadv(BlockDriverState *bs, CURLAIOCB *acb)
     trace_curl_setup_preadv(acb->bytes, start, state->range);
     curl_easy_setopt(state->curl, CURLOPT_RANGE, state->range);
 
-    curl_multi_add_handle(s->multi, state->curl);
+    if (curl_multi_add_handle(s->multi, state->curl) != CURLM_OK) {
+        state->acb[0] = NULL;
+        acb->ret = -EIO;
+
+        curl_clean_state(state);
+        goto out;
+    }
 
     /* Tell curl it needs to kick things off */
     curl_multi_socket_action(s->multi, CURL_SOCKET_TIMEOUT, 0, &running);