Re: [PATCH v3 08/10] qmp: teach 'getfd' to import sockets on win32

[Markus Armbruster <armbru@redhat.com>]

marcandre.lureau@redhat.com writes:

> From: Marc-André Lureau <marcandre.lureau@redhat.com>
>
> A process with enough capabilities can duplicate a socket to QEMU.
> Modify 'getfd' to import it and add it to the monitor fd list, so it can
> be later used by other commands.
>
> Note that we actually store the SOCKET in the FD list, appropriate care
> must now be taken to use the correct socket functions (similar approach
> is taken by our io/ code and in glib, this is internal and shouldn't
> affect the QEMU/QMP users)
>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  qapi/misc.json     | 16 ++++++++--
>  monitor/fds.c      | 79 ++++++++++++++++++++++++++++++++++++----------
>  monitor/hmp-cmds.c |  6 +++-
>  3 files changed, 81 insertions(+), 20 deletions(-)
>
> diff --git a/qapi/misc.json b/qapi/misc.json
> index 27ef5a2b20..cd36d8befb 100644
> --- a/qapi/misc.json
> +++ b/qapi/misc.json
> @@ -249,10 +249,18 @@
>  ##
>  # @getfd:
>  #
> -# Receive a file descriptor via SCM rights and assign it a name
> +# On UNIX, receive a file descriptor via SCM rights and assign it a name.
> +#
> +# On Windows, (where ancillary socket fd-passing isn't an option yet), add a
> +# socket that was duplicated to QEMU process with WSADuplicateSocketW() via
> +# WSASocket() & WSAPROTOCOL_INFOW structure and assign it a name. A SOCKET is
> +# considered as a kind of "file descriptor" in QMP context, for historical
> +# reasons and simplicity. QEMU takes care to use socket functions appropriately.

The Windows part explains things in terms of the C socket API.  Less
than ideal for the QEMU QMP Reference Manual, isn't it?  I don't know
nearly enough about this stuff to suggest concrete improvements...

What does this command do under Windows before this patch?  Fail always?

Wrap your lines a bit earlier, please.

>  #
>  # @fdname: file descriptor name
>  #
> +# @wsa-info: a WSAPROTOCOL_INFOW structure (encoded in base64). Since 8.0.
> +#

No way around passing a binary blob?

>  # Returns: Nothing on success
>  #
>  # Since: 0.14
> @@ -270,7 +278,11 @@
>  # <- { "return": {} }
>  #
>  ##
> -{ 'command': 'getfd', 'data': {'fdname': 'str'} }
> +{ 'command': 'getfd', 'data': {
> +    'fdname': 'str',
> +    '*wsa-info': {'type': 'str', 'if': 'CONFIG_WIN32'}
> +  }
> +}

What happens when QEMU runs on a Windows host and the client doesn't
pass @wsa-info?

>  
>  ##
>  # @closefd: