1nbd_can_meta_context(3)             LIBNBD             nbd_can_meta_context(3)
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NAME

6       nbd_can_meta_context - does the server support a specific meta context?
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SYNOPSIS

9        #include <libnbd.h>
10
11        int nbd_can_meta_context (
12              struct nbd_handle *h, const char *metacontext
13            );
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DESCRIPTION

16       Returns true if the server supports the given meta context (see
17       nbd_add_meta_context(3)).  Returns false if the server does not.  It is
18       possible for this command to fail if meta contexts were requested but
19       there is a missing or failed attempt at NBD_OPT_SET_META_CONTEXT during
20       option negotiation.
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22       If the server supports block status filtering (see
23       nbd_can_block_status_payload(3), this function must return true for any
24       filter name passed to nbd_block_status_filter(3).
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26       The single parameter is the name of the metadata context, for example
27       "LIBNBD_CONTEXT_BASE_ALLOCATION".  <libnbd.h> includes defined
28       constants for well-known namespace contexts beginning with
29       "LIBNBD_CONTEXT_", but you are free to pass in other contexts.
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31       This call does not block, because it returns data that is saved in the
32       handle from the NBD protocol handshake.
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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", "metacontext".  For
44       more information 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 1.0.
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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_CAN_META_CONTEXT 1
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SEE ALSO

59       nbd_add_meta_context(3), nbd_aio_block_status_64(3),
60       nbd_block_status_64(3), nbd_block_status_filter(3),
61       nbd_can_block_status_payload(3), nbd_create(3), nbd_opt_info(3),
62       nbd_opt_set_meta_context(3), nbd_set_request_meta_context(3), "Flag
63       calls" in libnbd(3), libnbd(3).
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AUTHORS

66       Eric Blake
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68       Richard W.M. Jones
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71       Copyright Red Hat
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LICENSE

74       This library is free software; you can redistribute it and/or modify it
75       under the terms of the GNU Lesser General Public License as published
76       by the Free Software Foundation; either version 2 of the License, or
77       (at your option) any later version.
78
79       This library is distributed in the hope that it will be useful, but
80       WITHOUT ANY WARRANTY; without even the implied warranty of
81       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
82       Lesser General Public License for more details.
83
84       You should have received a copy of the GNU Lesser General Public
85       License along with this library; if not, write to the Free Software
86       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
87       02110-1301 USA
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91libnbd-1.18.1                     2023-10-31           nbd_can_meta_context(3)
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