nbd_aio_opt_set_meta_context(3)     LIBNBD     nbd_aio_opt_set_meta_context(3)


NAME
       nbd_aio_opt_set_meta_context - select specific meta contexts, with
       implicit query list

SYNOPSIS
        #include <libnbd.h>

        typedef struct {
          int (*callback) (void *user_data, const char *name);
          void *user_data;
          void (*free) (void *user_data);
        } nbd_context_callback;

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

        int nbd_aio_opt_set_meta_context (
              struct nbd_handle *h,
              nbd_context_callback context_callback,
              nbd_completion_callback completion_callback
            );

DESCRIPTION
       Request that the server supply all recognized meta contexts registered
       through prior calls to nbd_add_meta_context(3), in conjunction with the
       export previously specified by the most recent nbd_set_export_name(3)
       or nbd_connect_uri(3).  This can only be used if nbd_set_opt_mode(3)
       enabled option mode.  Normally, this function is redundant, as
       nbd_opt_go(3) automatically does the same task if structured replies or
       extended headers have already been negotiated.  But manual control over
       meta context requests can be useful for fine-grained testing of how a
       server handles unusual negotiation sequences.  Often, use of this
       function is coupled with nbd_set_request_meta_context(3) to bypass the
       automatic context request normally performed by nbd_opt_go(3).

       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.

RETURN VALUE
       This call returns an integer >= 0.

ERRORS
       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).

HANDLE STATE
       nbd_aio_opt_set_meta_context 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                |
        <?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?>

VERSION
       This function first appeared in libnbd 1.16.

       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_SET_META_CONTEXT 1

SEE ALSO
       nbd_add_meta_context(3), nbd_aio_is_connecting(3),
       nbd_aio_opt_set_meta_context_queries(3), nbd_connect_uri(3),
       nbd_create(3), nbd_opt_go(3), nbd_opt_set_meta_context(3),
       nbd_set_export_name(3), nbd_set_opt_mode(3),
       nbd_set_request_meta_context(3), libnbd(3).

AUTHORS
       Eric Blake

       Richard W.M. Jones

COPYRIGHT
       Copyright Red Hat

LICENSE
       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-1.20.0                     2024-05-31   nbd_aio_opt_set_meta_context(3)