Re: [hurd-amd64] ibus test failures

[Diego Nieto Cid]

Hi,

On Tue, Dec 31, 2024 at 02:52:53PM +0100, Samuel Thibault wrote:
> 
> You should probably check precisely the difference between Linux and
> Hurd on these alignment questions at the various stages.
> 

I placed a `g_message` call in `g_unix_credentials_message_deserialize` and
on Linux it doesn't get triggered, it instead goes through 
`g_socket_get_credentials`:

    # GLib-GIO-DEBUG: Accepting "EXTERNAL" authentication
    # GLib-GIO-MESSAGE: [g_socket_get_credentials] optlen=12
    # GLib-GIO-DEBUG: Authorizing peer with credentials: 
GCredentials:linux-ucred:pid=87865,uid=1000,gid=1000

It takes the branch where G_CREDENTIALS_SOCKET_GET_CREDENTIALS_SUPPORTED
and SO_PEERCRED is defined.

This function gets called from gio/gdbusauth.c: _g_dbus_auth_run_server if
G_CREDENTIALS_PREFER_MESSAGE_PASSING is not defined (which is the case on 
Linux).

To summarize:

On Linux
========

    #define G_CREDENTIALS_UNIX_CREDENTIALS_MESSAGE_SUPPORTED 1
    #define G_CREDENTIALS_SOCKET_GET_CREDENTIALS_SUPPORTED 1
    #undef  G_CREDENTIALS_PREFER_MESSAGE_PASSING

    g_socket_get_credentials is called which uses getsockopt and SO_PEERCRED

On Hurd
=======

    #define G_CREDENTIALS_UNIX_CREDENTIALS_MESSAGE_SUPPORTED 1
    #undef  G_CREDENTIALS_SOCKET_GET_CREDENTIALS_SUPPORTED
    #define G_CREDENTIALS_PREFER_MESSAGE_PASSING 1

    g_unix_connection_receive_credentials is called which in turn calls:
      - g_unix_connection_receive_credentials
        - g_socket_receive_message
          - g_socket_control_message_deserialize
            - g_unix_credentials_message_deserialize


So, I went ahead and defined G_CREDENTIALS_PREFER_MESSAGE_PASSING on Linux
and to my surprise it didn't fail :P

Instead the correct size was being computed:

    # GLib-GIO-MESSAGE: [input_message_from_msghdr] 
level=1,type=2,len=28,extra=16
    # GLib-GIO-MESSAGE: [input_message_from_msghdr] 
cmsg=0x7ff46d6c5d40,data=0x7ff46d6c5d50
    # GLib-GIO-MESSAGE: [g_socket_control_message_deserialize] level=1, type=2, 
size=12
    # GLib-GIO-MESSAGE: [g_unix_credentials_message_deserialize] size=12, 
native=12

It must be something we are doing wrong on our side. I'll apply the logging to 
my Hurd
box and see what comes out.