1nbd_aio_opt_set_meta_context(3) LIBNBD nbd_aio_opt_set_meta_context(3)
2
6 nbd_aio_opt_set_meta_context - select specific meta contexts, with
7 implicit query list
8
10 #include <libnbd.h>
11 typedef struct {
13 int (*callback) (void *user_data, const char *name);
14 void *user_data;
15 void (*free) (void *user_data);
16 } nbd_context_callback;
17 typedef struct {
19 int (*callback) (void *user_data, int *error);
20 void *user_data;
21 void (*free) (void *user_data);
22 } nbd_completion_callback;
23 int nbd_aio_opt_set_meta_context (
25 struct nbd_handle *h,
26 nbd_context_callback context_callback,
27 nbd_completion_callback completion_callback
28 );
29
31 Request that the server supply all recognized meta contexts registered
32 through prior calls to nbd_add_meta_context(3), in conjunction with the
33 export previously specified by the most recent nbd_set_export_name(3)
34 or nbd_connect_uri(3). This can only be used if nbd_set_opt_mode(3)
35 enabled option mode. Normally, this function is redundant, as
36 nbd_opt_go(3) automatically does the same task if structured replies
37 have already been negotiated. But manual control over meta context
38 requests can be useful for fine-grained testing of how a server handles
39 unusual negotiation sequences. Often, use of this function is coupled
40 with nbd_set_request_meta_context(3) to bypass the automatic context
41 request normally performed by nbd_opt_go(3).
42 To determine when the request completes, wait for
44 nbd_aio_is_connecting(3) to return false. Or supply the optional
45 "completion_callback" which will be invoked as described in "Completion
46 callbacks" in libnbd(3), except that it is automatically retired
47 regardless of return value. Note that detecting whether the server
48 returns an error (as is done by the return value of the synchronous
49 counterpart) is only possible with a completion callback.
50
52 This call returns an integer ≥ 0.
53
55 On error -1 is returned.
56 Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
58 of the error.
59 The following parameters must not be NULL: "h". For more information
61 see "Non-NULL parameters" in libnbd(3).
62
64 The handle must be negotiating, otherwise this call will return an
65 error.
66
68 This function first appeared in libnbd 1.16.
69 If you need to test if this function is available at compile time check
71 if the following macro is defined:
72 #define LIBNBD_HAVE_NBD_AIO_OPT_SET_META_CONTEXT 1
74
76 nbd_add_meta_context(3), nbd_aio_is_connecting(3),
77 nbd_aio_opt_set_meta_context_queries(3), nbd_connect_uri(3),
78 nbd_create(3), nbd_opt_go(3), nbd_opt_set_meta_context(3),
79 nbd_set_export_name(3), nbd_set_opt_mode(3),
80 nbd_set_request_meta_context(3), libnbd(3).
81
83 Eric Blake
84 Richard W.M. Jones
86
88 Copyright Red Hat
89
91 This library is free software; you can redistribute it and/or modify it
92 under the terms of the GNU Lesser General Public License as published
93 by the Free Software Foundation; either version 2 of the License, or
94 (at your option) any later version.
95 This library is distributed in the hope that it will be useful, but
97 WITHOUT ANY WARRANTY; without even the implied warranty of
98 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
99 Lesser General Public License for more details.
100 You should have received a copy of the GNU Lesser General Public
102 License along with this library; if not, write to the Free Software
103 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
104 02110-1301 USA
105libnbd-1.16.5 2023-09-26 nbd_aio_opt_set_meta_context(3)