iotests: Introduce qemu_nbd_list_log()

Add a function to list the NBD exports offered by an NBD server.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200924152717.287415-30-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/iotests.py

@@ -65,7 +65,8 @@
     qemu_io_args_no_fmt += \
         os.environ['QEMU_IO_OPTIONS_NO_FMT'].strip().split(' ')
 
-qemu_nbd_args = [os.environ.get('QEMU_NBD_PROG', 'qemu-nbd')]
+qemu_nbd_prog = os.environ.get('QEMU_NBD_PROG', 'qemu-nbd')
+qemu_nbd_args = [qemu_nbd_prog]
 if os.environ.get('QEMU_NBD_OPTIONS'):
     qemu_nbd_args += os.environ['QEMU_NBD_OPTIONS'].strip().split(' ')
 
@@ -280,6 +281,13 @@ def qemu_nbd_early_pipe(*args: str) -> Tuple[int, str]:
                                                    connect_stderr=False)
     return returncode, output if returncode else ''
 
+def qemu_nbd_list_log(*args: str) -> str:
+    '''Run qemu-nbd to list remote exports'''
+    full_args = [qemu_nbd_prog, '-L'] + list(args)
+    output, _ = qemu_tool_pipe_and_status('qemu-nbd', full_args)
+    log(output, filters=[filter_testfiles, filter_nbd_exports])
+    return output
+
 @contextmanager
 def qemu_nbd_popen(*args):
     '''Context manager running qemu-nbd within the context'''
@@ -413,6 +421,9 @@ def _filter(_key, value):
         return value
     return filter_qmp(qmsg, _filter)
 
+def filter_nbd_exports(output: str) -> str:
+    return re.sub(r'((min|opt|max) block): [0-9]+', r'\1: XXX', output)
+
 
 Msg = TypeVar('Msg', Dict[str, Any], List[Any], str)