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.IX Title "nbd_set_request_meta_context 3"
.TH nbd_set_request_meta_context 3 2024-05-31 libnbd-1.20.0 LIBNBD
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH NAME
nbd_set_request_meta_context \- control whether connect automatically
requests meta contexts
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\& #include <libnbd.h>
\&
\& int nbd_set_request_meta_context (
\&       struct nbd_handle *h, bool request
\&     );
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
This function controls whether the act of connecting to an export
(all \f(CW\*(C`nbd_connect_*\*(C'\fR calls when \fBnbd_set_opt_mode\fR\|(3) is false,
or \fBnbd_opt_go\fR\|(3) and \fBnbd_opt_info\fR\|(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 \fBnbd_add_meta_context\fR\|(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 \fBnbd_opt_set_meta_context\fR\|(3)
at other times in the negotiation sequence; and even when using
just \fBnbd_opt_info\fR\|(3), it can be faster to collect the server's
results by relying on the callback function passed to
\&\fBnbd_opt_list_meta_context\fR\|(3) than a series of post-process
calls to \fBnbd_can_meta_context\fR\|(3).
.PP
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 \fBnbd_add_meta_context\fR\|(3).
Setting this control to false may cause \fBnbd_block_status\fR\|(3)
to fail.
.SH "RETURN VALUE"
.IX Header "RETURN VALUE"
If the call is successful the function returns \f(CW0\fR.
.SH ERRORS
.IX Header "ERRORS"
On error \f(CW\-1\fR is returned.
.PP
Refer to "ERROR HANDLING" in \fBlibnbd\fR\|(3)
for how to get further details of the error.
.PP
The following parameters must not be NULL: \f(CW\*(C`h\*(C'\fR.
For more information see "Non-NULL parameters" in \fBlibnbd\fR\|(3).
.SH "HANDLE STATE"
.IX Header "HANDLE STATE"
nbd_set_request_meta_context
can be called when the handle is in the following states:
.PP
.Vb 8
\& ┌─────────────────────────────────────┬─────────────────────────┐
\& │ Handle created, before connecting   │ ✅ allowed              │
\& │ Connecting                          │ ❌ error                │
\& │ Connecting & handshaking (opt_mode) │ ✅ allowed              │
\& │ Connected to the server             │ ❌ error                │
\& │ Connection shut down                │ ❌ error                │
\& │ Handle dead                         │ ❌ error                │
\& └─────────────────────────────────────┴─────────────────────────┘
.Ve
.SH VERSION
.IX Header "VERSION"
This function first appeared in libnbd 1.16.
.PP
If you need to test if this function is available at compile time
check if the following macro is defined:
.PP
.Vb 1
\& #define LIBNBD_HAVE_NBD_SET_REQUEST_META_CONTEXT 1
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBnbd_add_meta_context\fR\|(3),
\&\fBnbd_block_status\fR\|(3),
\&\fBnbd_can_meta_context\fR\|(3),
\&\fBnbd_create\fR\|(3),
\&\fBnbd_get_request_meta_context\fR\|(3),
\&\fBnbd_get_structured_replies_negotiated\fR\|(3),
\&\fBnbd_opt_go\fR\|(3),
\&\fBnbd_opt_info\fR\|(3),
\&\fBnbd_opt_list_meta_context\fR\|(3),
\&\fBnbd_opt_set_meta_context\fR\|(3),
\&\fBnbd_set_opt_mode\fR\|(3),
\&\fBlibnbd\fR\|(3).
.SH AUTHORS
.IX Header "AUTHORS"
Eric Blake
.PP
Richard W.M. Jones
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright Red Hat
.SH LICENSE
.IX Header "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.
.PP
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.
.PP
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