1nbd_opt_info(3)                     LIBNBD                     nbd_opt_info(3)
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NAME

6       nbd_opt_info - request the server for information about an export
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SYNOPSIS

9        #include <libnbd.h>
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11        int nbd_opt_info (
12              struct nbd_handle *h
13            );
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DESCRIPTION

16       Request that the server supply information about the export name
17       previously specified by the most recent nbd_set_export_name(3) or
18       nbd_connect_uri(3).  This can only be used if nbd_set_opt_mode(3)
19       enabled option mode.
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21       If successful, functions like nbd_is_read_only(3) and nbd_get_size(3)
22       will report details about that export.  If
23       nbd_set_request_meta_context(3) is set (the default) and structured
24       replies were negotiated, it is also valid to use
25       nbd_can_meta_context(3) after this call.  However, it may be more
26       efficient to clear that setting and manually utilize
27       nbd_opt_list_meta_context(3) with its callback approach, for learning
28       which contexts an export supports.  In general, if nbd_opt_go(3) is
29       called next, that call will likely succeed with the details remaining
30       the same, although this is not guaranteed by all servers.
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32       Not all servers understand this request, and even when it is
33       understood, the server might fail the request even when a corresponding
34       nbd_opt_go(3) would succeed.
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RETURN VALUE

37       If the call is successful the function returns 0.
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ERRORS

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

49       The handle must be negotiating, otherwise this call will return an
50       error.
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VERSION

53       This function first appeared in libnbd 1.4.
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55       If you need to test if this function is available at compile time check
56       if the following macro is defined:
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58        #define LIBNBD_HAVE_NBD_OPT_INFO 1
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SEE ALSO

61       nbd_aio_opt_info(3), nbd_can_meta_context(3), nbd_connect_uri(3),
62       nbd_create(3), nbd_get_size(3), nbd_is_read_only(3), nbd_opt_go(3),
63       nbd_opt_list_meta_context(3), nbd_set_export_name(3),
64       nbd_set_opt_mode(3), nbd_set_request_meta_context(3), 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-1.16.5                     2023-09-26                   nbd_opt_info(3)
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