nbd_aio_opt_extended_headers - request the server to enable extended headers

       Eric Blake

       Richard W.M. Jones

       Copyright Red Hat

       Request that the server use extended headers, by sending "NBD_OPT_EXTENDED_HEADERS".  This behaves like
       the synchronous counterpart nbd_opt_extended_headers(3), except that it does not wait for the server's
       response.

       To determine when the request completes, wait for nbd_aio_is_connecting(3) to return false.  Or supply
       the optional "completion_callback" which will be invoked as described in "Completion callbacks" in
       libnbd(3), except that it is automatically retired regardless of return value.  Note that detecting
       whether the server returns an error (as is done by the return value of the synchronous counterpart) is
       only possible with a completion callback.

       On error -1 is returned.

       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details of the error.

       The following parameters must not be NULL: "h".  For more information see "Non-NULL parameters" in
       libnbd(3).

       nbd_aio_opt_extended_headers can be called when the handle is in the following state:

        ┌─────────────────────────────────────┬─────────────────────────┐
        │ Handle created, before connecting   │ ❌ error                │
        │ Connecting                          │ ❌ error                │
        │ Connecting & handshaking (opt_mode) │ ✅ allowed              │
        │ Connected to the server             │ ❌ error                │
        │ Connection shut down                │ ❌ error                │
        │ Handle dead                         │ ❌ error                │
        └─────────────────────────────────────┴─────────────────────────┘

       This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser
       General Public License as published by the Free Software Foundation; either version 2 of the License, or
       (at your option) any later version.

       This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
       the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General
       Public License for more details.

       You should have received a copy of the GNU Lesser General Public License along with this library; if not,
       write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

libnbd-1.22.2                                      2025-06-16                    nbd_aio_opt_extended_headers(3)

       nbd_aio_opt_extended_headers - request the server to enable extended headers

       If the call is successful the function returns 0.

nbd_aio_is_connecting(3), nbd_create(3), nbd_opt_extended_headers(3), nbd_set_opt_mode(3), libnbd(3).

        #include <libnbd.h>

        typedef struct {
          int (*callback) (void *user_data, int *error);
          void *user_data;
          void (*free) (void *user_data);
        } nbd_completion_callback;

        int nbd_aio_opt_extended_headers (
              struct nbd_handle *h,
              nbd_completion_callback completion_callback
            );

       This function first appeared in libnbd 1.18.

       If you need to test if this function is available at compile time check if the following macro is
       defined:

        #define LIBNBD_HAVE_NBD_AIO_OPT_EXTENDED_HEADERS 1