Re: [PATCH v2 13/39] python, tests: switch usernet queries from HMP to QMP

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Jun 26, 2026 at 01:19:14AM +0400, Marc-André Lureau wrote:
> Replace human-monitor-command "info usernet" calls with the structured
> x-query-usernet QMP command in get_usernet_hostfwd_port() and the VM
> test runner boot path.
> 
> Since x-query-usernet returns a list of UsernetInfo entries, callers
> now iterate over the result and extract the port from each entry's
> "info" field. Also switch get_info_usernet_hostfwd_port() from
> split('\r\n') to splitlines(), since QMP strings use \n rather than
> the HMP monitor's \r\n line endings.
> 
> Signed-off-by: Marc-Andre Lureau <marcandre.lureau@redhat.com>
> ---
>  python/qemu/utils/__init__.py       |  5 +++--
>  tests/functional/qemu_test/utils.py |  8 ++++++--
>  tests/vm/basevm.py                  | 13 ++++++++-----
>  3 files changed, 17 insertions(+), 9 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

> 
> diff --git a/python/qemu/utils/__init__.py b/python/qemu/utils/__init__.py
> index be5daa83634..e32911d4c6d 100644
> --- a/python/qemu/utils/__init__.py
> +++ b/python/qemu/utils/__init__.py
> @@ -46,10 +46,11 @@ def get_info_usernet_hostfwd_port(info_usernet_output: str) -> Optional[int]:
>      """
>      Returns the port given to the hostfwd parameter via info usernet
>  
> -    :param info_usernet_output: output generated by hmp command "info usernet"
> +    :param info_usernet_output: output generated by "info usernet" or
> +        the "info" field from x-query-usernet
>      :return: the port number allocated by the hostfwd option
>      """
> -    for line in info_usernet_output.split('\r\n'):
> +    for line in info_usernet_output.splitlines():
>          regex = r'TCP.HOST_FORWARD.*127\.0\.0\.1\s+(\d+)\s+10\.'
>          match = re.search(regex, line)
>          if match is not None:
> diff --git a/tests/functional/qemu_test/utils.py b/tests/functional/qemu_test/utils.py
> index 826c267785b..0992db49ab2 100644
> --- a/tests/functional/qemu_test/utils.py
> +++ b/tests/functional/qemu_test/utils.py
> @@ -14,8 +14,12 @@
>  
>  
>  def get_usernet_hostfwd_port(vm):
> -    res = vm.cmd('human-monitor-command', command_line='info usernet')
> -    return get_info_usernet_hostfwd_port(res)
> +    res = vm.cmd('x-query-usernet')

I think there's an error handling behaviour difference here.

HMP has no concept of errors, just stuffing messages onto stderr.

So in !CONFIG_SLIRP scenarios this "info usernet" command
probably didn't return an error that this code would detect.
I think get_info_usernet_hostfwd_port() simply wouldn't
find a port number.

x-query-usernet by contrast will have clear error handling,
so should raise an exception in !CONFIG_SLIRP scenarios
which will break callers of this method I expect

> +    for entry in res:
> +        port = get_info_usernet_hostfwd_port(entry['info'])
> +        if port is not None:
> +            return port
> +    return None
>  
>  def pow2ceil(x):
>      """
> diff --git a/tests/vm/basevm.py b/tests/vm/basevm.py
> index 9e879e966a3..198b04e8c37 100644
> --- a/tests/vm/basevm.py
> +++ b/tests/vm/basevm.py
> @@ -312,12 +312,15 @@ def boot(self, img, extra_args=[]):
>          self._guest = guest
>          # Init console so we can start consuming the chars.
>          self.console_init()
> -        usernet_info = guest.cmd("human-monitor-command",
> -                                 command_line="info usernet")
> -        self.ssh_port = get_info_usernet_hostfwd_port(usernet_info)
> +        res = guest.cmd("x-query-usernet")

Same concern here about likely breaking in !CONFIG_SLIRP
scenarios

> +        for entry in res:
> +            port = get_info_usernet_hostfwd_port(entry['info'])
> +            if port is not None:
> +                self.ssh_port = port
> +                break
>          if not self.ssh_port:
> -            raise Exception("Cannot find ssh port from 'info usernet':\n%s" % \
> -                            usernet_info)
> +            raise Exception("Cannot find ssh port from"
> +                            " 'x-query-usernet': %s" % res)
>  
>      def console_init(self, timeout = None):
>          if timeout == None:
> 
> -- 
> 2.54.0
> 

With regards,
Daniel
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