[Libguestfs] [libnbd PATCH v5 3/4] generator: Add APIs to get/set the socket activation socket name

[Eric Blake]

On Sat, Mar 25, 2023 at 12:39:28PM +0100, Laszlo Ersek wrote:
> From: "Richard W.M. Jones" <rjones at redhat.com>
> 
> To allow us to name the socket passed down to the NBD server when
> calling nbd_connect_systemd_socket_activation(3), we need to add the
> field to the handle and add access functions.
> 
> [Laszlo's notes:
> 
> - Originally posted by Rich at
>   <https://listman.redhat.com/archives/libguestfs/2023-January/030557.html>
>   (Message-Id: <20230130225521.1771496-4-rjones at redhat.com>).
> 
> - I've renamed "sa_name" to "sact_name", due to <signal.h> reserving
>   symbols with the "sa_" prefix. This corresponds to earlier patches in
>   this series, such as 'socket activation: rename sa_(tmpdir|sockpath) to
>   sact_(tmpdir|sockpath)' and 'ocaml: rename "sa_u" to "saddr_u"'.
> 
> - Restricted "set_socket_activation_name" to the "Created" state, per
>   Eric's recommendation
>   <http://mid.mail-archive.com/n6lzl7ii5m4hu77n7rrzm3uih3tnx457e4y67rghki34b2ghh7@7vyini26mqko>.
> 
> - Documented that we are going to pass "unknown" if "socket_name" is set
>   to the empty string
>   <http://mid.mail-archive.com/oqwjnjvq4phqr76yum6zo5erfrm3tvmyewr5nxru3oxklobpgp@4plkku7opujw>.]
> 
> Signed-off-by: Laszlo Ersek <lersek at redhat.com>
> Reviewed-by: Eric Blake <eblake at redhat.com>
> ---
> 

>  
> +  "set_socket_activation_name", {
> +    default_call with
> +    args = [ String "socket_name" ]; ret = RErr;
> +    permitted_states = [ Created ];
> +    shortdesc = "set the socket activation name";
> +    longdesc = "\
> +When running an NBD server using
> +L<nbd_connect_systemd_socket_activation(3)> you can optionally
> +name the socket.  Call this function before connecting to the
> +server.
> +
> +Some servers such as L<qemu-storage-daemon(1)>
> +can use this information to associate the socket with a name
> +used on the command line, but most servers will ignore it.
> +The name is passed through the C<LISTEN_FDNAMES> environment
> +variable.
> +
> +The parameter C<socket_name> can be a short alphanumeric string.
> +If it is set to the empty string (also the default when the handle
> +is created) then the name C<unknown> will be seen by the server.";

Accurate,

> +    see_also = [Link "connect_systemd_socket_activation";
> +                Link "get_socket_activation_name"];
> +  };
> +
> +  "get_socket_activation_name", {
> +    default_call with
> +    args = []; ret = RString;
> +    shortdesc = "get the socket activation name";
> +    longdesc = "\
> +Return the socket name used when you call
> +L<nbd_connect_systemd_socket_activation(3)> on the same
> +handle.  By default this will return the empty string
> +meaning that no name is passed to the server.";

slightly misleading. Maybe: 'By default this will return the empty
string meaning that a server will see the name C<unknown>'.

Other than that, this series looks good to go from my end.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org