curl: Ensure all informationals are checked for completion

According to the documentation, the correct way to ensure all
informationals have been returned by curl_multi_info_read is to loop
until it returns NULL.
Signed-off-by: NMatthew Booth <mbooth@redhat.com>
Tested-by: NRichard W.M. Jones <rjones@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/curl.c

@@ -248,46 +248,39 @@ static void curl_multi_check_completion(BDRVCURLState *s)
 
     /* Try to find done transfers, so we can free the easy
      * handle again. */
-    do {
+    for (;;) {
         CURLMsg *msg;
         msg = curl_multi_info_read(s->multi, &msgs_in_queue);
 
+        /* Quit when there are no more completions */
         if (!msg)
             break;
-        if (msg->msg == CURLMSG_NONE)
-            break;
 
-        switch (msg->msg) {
-            case CURLMSG_DONE:
-            {
-                CURLState *state = NULL;
-                curl_easy_getinfo(msg->easy_handle, CURLINFO_PRIVATE,
-                                  (char **)&state);
-
-                /* ACBs for successful messages get completed in curl_read_cb */
-                if (msg->data.result != CURLE_OK) {
-                    int i;
-                    for (i = 0; i < CURL_NUM_ACB; i++) {
-                        CURLAIOCB *acb = state->acb[i];
-
-                        if (acb == NULL) {
-                            continue;
-                        }
-
-                        acb->common.cb(acb->common.opaque, -EIO);
-                        qemu_aio_release(acb);
-                        state->acb[i] = NULL;
+        if (msg->msg == CURLMSG_DONE) {
+            CURLState *state = NULL;
+            curl_easy_getinfo(msg->easy_handle, CURLINFO_PRIVATE,
+                              (char **)&state);
+
+            /* ACBs for successful messages get completed in curl_read_cb */
+            if (msg->data.result != CURLE_OK) {
+                int i;
+                for (i = 0; i < CURL_NUM_ACB; i++) {
+                    CURLAIOCB *acb = state->acb[i];
+
+                    if (acb == NULL) {
+                        continue;
                     }
-                }
 
-                curl_clean_state(state);
-                break;
+                    acb->common.cb(acb->common.opaque, -EIO);
+                    qemu_aio_release(acb);
+                    state->acb[i] = NULL;
+                }
             }
-            default:
-                msgs_in_queue = 0;
-                break;
+
+            curl_clean_state(state);
+            break;
         }
-    } while(msgs_in_queue);
+    }
 }
 
 static void curl_multi_do(void *arg)