daemon: stream: Don't force error when client aborts

Every time a client aborts a stream via the virStreamAbort API,
the daemon always logs an error like:

  error : daemonStreamHandleAbort:617 : stream aborted at client request

and that same error is returned to the client. Meaning virStreamAbort
always returns -1, which seems strange.

This reworks the error handling to only raise an error on virStreamAbort
if the actual server side abort call raises an error. This is similar
to how virStreamFinish works.

If the abort code path is triggered by an unexpected message type
then we continue to raise an unconditional error. Also drop a redundant
VIR_WARN call there, since virReportError will raise a VIR_ERROR anyways

daemon/stream.c

@@ -611,29 +611,40 @@ daemonStreamHandleAbort(virNetServerClientPtr client,
 {
     VIR_DEBUG("client=%p, stream=%p, proc=%d, serial=%u",
               client, stream, msg->header.proc, msg->header.serial);
-    virNetMessageError rerr;
-
-    memset(&rerr, 0, sizeof(rerr));
+    int ret;
+    bool raise_error = false;
 
     stream->closed = true;
     virStreamEventRemoveCallback(stream->st);
-    virStreamAbort(stream->st);
+    ret = virStreamAbort(stream->st);
 
     if (msg->header.status == VIR_NET_ERROR) {
-        virReportError(VIR_ERR_RPC,
-                       "%s", _("stream aborted at client request"));
+        VIR_INFO("stream aborted at client request");
+        raise_error = (ret < 0);
     } else {
-        VIR_WARN("unexpected stream status %d", msg->header.status);
         virReportError(VIR_ERR_RPC,
                        _("stream aborted with unexpected status %d"),
                        msg->header.status);
+        raise_error = true;
     }
 
-    return virNetServerProgramSendReplyError(remoteProgram,
-                                             client,
-                                             msg,
-                                             &rerr,
-                                             &msg->header);
+    if (raise_error) {
+        virNetMessageError rerr;
+        memset(&rerr, 0, sizeof(rerr));
+        return virNetServerProgramSendReplyError(remoteProgram,
+                                                 client,
+                                                 msg,
+                                                 &rerr,
+                                                 &msg->header);
+    } else {
+        /* Send zero-length confirm */
+        return virNetServerProgramSendStreamData(stream->prog,
+                                                 client,
+                                                 msg,
+                                                 stream->procedure,
+                                                 stream->serial,
+                                                 NULL, 0);
+    }
 }