1nbd_get_extended_headers_negotiated(3L)IBNBnDbd_get_extended_headers_negotiated(3)
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NAME

6       nbd_get_extended_headers_negotiated - see if extended headers are in
7       use
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SYNOPSIS

10        #include <libnbd.h>
11
12        int nbd_get_extended_headers_negotiated (
13              struct nbd_handle *h
14            );
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DESCRIPTION

17       After connecting you may call this to find out if the connection is
18       using extended headers.  Note that this setting is sticky; this can
19       return true even after a second nbd_opt_extended_headers(3) returns
20       false because the server detected a duplicate request.
21
22       When extended headers are not in use, commands are limited to a 32-bit
23       length, even when the libnbd API uses a 64-bit parameter to express the
24       length.  But even when extended headers are supported, the server may
25       enforce other limits, visible through nbd_get_block_size(3).
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27       Note that when extended headers are negotiated, you should prefer the
28       use of nbd_block_status_64(3) instead of nbd_block_status(3) if any of
29       the meta contexts you requested via nbd_add_meta_context(3) might
30       return 64-bit status values; however, all of the well-known meta
31       contexts covered by current "LIBNBD_CONTEXT_*" constants only return
32       32-bit status.
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RETURN VALUE

35       This call returns a boolean value.
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ERRORS

38       On error -1 is returned.
39
40       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
41       of the error.
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43       The following parameters must not be NULL: "h".  For more information
44       see "Non-NULL parameters" in libnbd(3).
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HANDLE STATE

47       The handle must be negotiating, or connected with the server, or shut
48       down, otherwise this call will return an error.
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VERSION

51       This function first appeared in libnbd 1.18.
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53       If you need to test if this function is available at compile time check
54       if the following macro is defined:
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56        #define LIBNBD_HAVE_NBD_GET_EXTENDED_HEADERS_NEGOTIATED 1
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SEE ALSO

59       nbd_add_meta_context(3), nbd_block_status(3), nbd_block_status_64(3),
60       nbd_cache(3), nbd_create(3), nbd_get_block_size(3),
61       nbd_get_protocol(3), nbd_get_request_extended_headers(3),
62       nbd_get_structured_replies_negotiated(3), nbd_opt_extended_headers(3),
63       nbd_set_request_extended_headers(3), nbd_trim(3), nbd_zero(3),
64       libnbd(3).
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AUTHORS

67       Eric Blake
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69       Richard W.M. Jones
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72       Copyright Red Hat
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LICENSE

75       This library is free software; you can redistribute it and/or modify it
76       under the terms of the GNU Lesser General Public License as published
77       by the Free Software Foundation; either version 2 of the License, or
78       (at your option) any later version.
79
80       This library is distributed in the hope that it will be useful, but
81       WITHOUT ANY WARRANTY; without even the implied warranty of
82       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
83       Lesser General Public License for more details.
84
85       You should have received a copy of the GNU Lesser General Public
86       License along with this library; if not, write to the Free Software
87       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
88       02110-1301 USA
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92libnbd-1.18.1                     2023-10n-b3d1_get_extended_headers_negotiated(3)
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