Re: [hurd-amd64] ibus test failures

[Diego Nieto Cid]

On Sun, Dec 29, 2024 at 11:33:47PM +0100, Samuel Thibault wrote:
>
> See the error test, it's about G_CREDENTIALS_NATIVE_SIZE, see its
> definition:
> 
> #define G_CREDENTIALS_NATIVE_SIZE (sizeof (struct cmsgcred))
> 
> And the definition of struct cmsgcred in bits/socket.h
> 

I wrote a little test-case (attached) that compares several sizes of the objects
involved in the GBus authentication.

Here are the results for `hurd-amd64`:

    $ cc -I/usr/include/glib-2.0 -I/usr/lib/x86_64-gnu/glib-2.0/include \
        -pthread  cred_size.c  -lgio-2.0 -lgobject-2.0 -lglib-2.0 \
        -o cred_size

    $ ./cred_size
    sizeof (int): 4
    sizeof(struct cmsgcred): 84
    CMSG_LEN(sizeof (int)): 20
    CMSG_LEN(g_socket_control_message_get_size (scm)): 100

and here the results for `hurd-i386`:

    $ ./cred_size
    sizeof (int): 4
    sizeof(struct cmsgcred): 84
    CMSG_LEN(sizeof (int)): 16
    CMSG_LEN(g_socket_control_message_get_size (scm)): 96

So, it seems CMSG_LEN generates sizes that are off by 4 bytes.

I'll check the macro next, to see if I can pinpoint that extra 4 bytes.

Thanks

#include <gio/gio.h>
#include <stdio.h>
#include <sys/socket.h>

int
main(int argc, char **argv)
{
  size_t int_size = sizeof (int);
  printf("sizeof (int): %lu\n", int_size);

  size_t cred_size = sizeof(struct cmsgcred);
  printf("sizeof(struct cmsgcred): %lu\n", cred_size);

  size_t cmsg_len = CMSG_LEN(sizeof (int));
  printf("CMSG_LEN(sizeof (int)): %lu\n", cmsg_len);

  GCredentials *creds = g_credentials_new();
  GSocketControlMessage *scm = g_unix_credentials_message_new_with_credentials(creds);
  size_t cms = CMSG_LEN(g_socket_control_message_get_size (scm));
  printf("CMSG_LEN(g_socket_control_message_get_size (scm)): %lu\n", cms);

  return 0;
}
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