nbd_set_request_meta_context(3)     LIBNBD     nbd_set_request_meta_context(3)


NAME
       nbd_set_request_meta_context - control whether connect automatically
       requests meta contexts

SYNOPSIS
        #include <libnbd.h>

        int nbd_set_request_meta_context (
              struct nbd_handle *h, bool request
            );

DESCRIPTION
       This function controls whether the act of connecting to an export (all
       "nbd_connect_*" calls when nbd_set_opt_mode(3) is false, or
       nbd_opt_go(3) and nbd_opt_info(3) when option mode is enabled) will
       also try to issue NBD_OPT_SET_META_CONTEXT when the server supports
       structured replies or extended headers and any contexts were registered
       by nbd_add_meta_context(3).  The default setting is true; however the
       extra step of negotiating meta contexts is not always desirable:
       performing both info and go on the same export works without needing to
       re-negotiate contexts on the second call; integration testing of other
       servers may benefit from manual invocation of
       nbd_opt_set_meta_context(3) at other times in the negotiation sequence;
       and even when using just nbd_opt_info(3), it can be faster to collect
       the server's results by relying on the callback function passed to
       nbd_opt_list_meta_context(3) than a series of post-process calls to
       nbd_can_meta_context(3).

       Note that this control has no effect if the server does not negotiate
       structured replies or extended headers, or if the client did not
       request any contexts via nbd_add_meta_context(3).  Setting this control
       to false may cause nbd_block_status(3) to fail.

RETURN VALUE
       If the call is successful the function returns 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_set_request_meta_context can be called when the handle is in the
       following states:

        <?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?><?>
        | Handle created, before connecting   | <?> allowed              |
        | 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_SET_REQUEST_META_CONTEXT 1

SEE ALSO
       nbd_add_meta_context(3), nbd_block_status(3), nbd_can_meta_context(3),
       nbd_create(3), nbd_get_request_meta_context(3),
       nbd_get_structured_replies_negotiated(3), nbd_opt_go(3),
       nbd_opt_info(3), nbd_opt_list_meta_context(3),
       nbd_opt_set_meta_context(3), nbd_set_opt_mode(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_set_request_meta_context(3)