From 2f7ffaddd0a233a233125320b6595a091c19c18f Mon Sep 17 00:00:00 2001
From: Eric Blake <eblake@redhat.com>
Date: Fri, 6 Oct 2017 19:24:07 +0200
Subject: [PATCH 15/34] qemu-iotests: improve nbd-fault-injector.py startup
 protocol

RH-Author: Eric Blake <eblake@redhat.com>
Message-id: <20171006192409.29915-3-eblake@redhat.com>
Patchwork-id: 76914
O-Subject: [RHEV-7.5 qemu-kvm-rhev PATCH 2/4] qemu-iotests: improve nbd-fault-injector.py startup protocol
Bugzilla: 1482478
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

From: Stefan Hajnoczi <stefanha@redhat.com>

Currently 083 waits for the nbd-fault-injector.py server to start up by
looping until netstat shows the TCP listen socket.

The startup protocol can be simplified by passing a 0 port number to
nbd-fault-injector.py.  The kernel will allocate a port in bind(2) and
the final port number can be printed by nbd-fault-injector.py.

This should make it slightly nicer and less TCP-specific to wait for
server startup.  This patch changes nbd-fault-injector.py, the next one
will rewrite server startup in 083.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20170829122745.14309-3-stefanha@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
(cherry picked from commit 6e592fc92234a58c7156c385840633c17dedd24f)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 tests/qemu-iotests/nbd-fault-injector.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tests/qemu-iotests/nbd-fault-injector.py b/tests/qemu-iotests/nbd-fault-injector.py
index 6c07191..1c10dcb 100755
--- a/tests/qemu-iotests/nbd-fault-injector.py
+++ b/tests/qemu-iotests/nbd-fault-injector.py
@@ -235,11 +235,15 @@ def open_socket(path):
         sock = socket.socket()
         sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
         sock.bind((host, int(port)))
+
+        # If given port was 0 the final port number is now available
+        path = '%s:%d' % sock.getsockname()
     else:
         sock = socket.socket(socket.AF_UNIX)
         sock.bind(path)
     sock.listen(0)
     print 'Listening on %s' % path
+    sys.stdout.flush() # another process may be waiting, show message now
     return sock
 
 def usage(args):
-- 
1.8.3.1