nbd_get_canonical_export_name(3)

1nbd_get_canonical_export_name(3)    LIBNBD    nbd_get_canonical_export_name(3)
2
3
4

NAME

6       nbd_get_canonical_export_name - return the canonical export name, if
7       the server has one
8

SYNOPSIS

10        #include <libnbd.h>
11
12        char * nbd_get_canonical_export_name (
13                 struct nbd_handle *h
14               );
15

DESCRIPTION

17       The NBD protocol permits a server to report an optional canonical
18       export name, which may differ from the client's request (as set by
19       nbd_set_export_name(3) or nbd_connect_uri(3)).  This function accesses
20       any name returned by the server; it may be the same as the client
21       request, but is more likely to differ when the client requested a
22       connection to the default export name (an empty string "").
23
24       Some servers are unlikely to report a canonical name unless the client
25       specifically hinted about wanting it, via nbd_set_full_info(3).
26

RETURN VALUE

28       This call returns a string.  The caller must free the returned string
29       to avoid a memory leak.
30

ERRORS

32       On error "NULL" is returned.
33
34       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
35       of the error.
36
37       The following parameters must not be NULL: "h".  For more information
38       see "Non-NULL parameters" in libnbd(3).
39

HANDLE STATE

41       The handle must be negotiating, or connected with the server, or shut
42       down, otherwise this call will return an error.
43

VERSION

45       This function first appeared in libnbd 1.4.
46
47       If you need to test if this function is available at compile time check
48       if the following macro is defined:
49
50        #define LIBNBD_HAVE_NBD_GET_CANONICAL_EXPORT_NAME 1
51

EXAMPLE

53       This example is also available as examples/server-flags.c in the libnbd
54       source code.
55
56        /* This example shows how to connect to an NBD
57         * server and print the export flags.
58         *
59         * You can test it with nbdkit like this:
60         *
61         * nbdkit -U - memory 1M \
62         *   --run './server-flags $unixsocket'
63         */
64
65        #include <stdio.h>
66        #include <stdlib.h>
67
68        #include <libnbd.h>
69
70        int
71        main (int argc, char *argv[])
72        {
73          struct nbd_handle *nbd;
74          char *str;
75          int flag;
76
77          if (argc != 2) {
78            fprintf (stderr, "%s socket\n", argv[0]);
79            exit (EXIT_FAILURE);
80          }
81
82          /* Create the libnbd handle. */
83          nbd = nbd_create ();
84          if (nbd == NULL) {
85            fprintf (stderr, "%s\n", nbd_get_error ());
86            exit (EXIT_FAILURE);
87          }
88
89          /* Request full information. */
90        #if LIBNBD_HAVE_NBD_SET_FULL_INFO /* Added in 1.4 */
91          if (nbd_set_full_info (nbd, true) == -1) {
92            fprintf (stderr, "%s\n", nbd_get_error ());
93            exit (EXIT_FAILURE);
94          }
95        #endif
96
97          /* Connect to the NBD server over a
98           * Unix domain socket.
99           */
100          if (nbd_connect_unix (nbd, argv[1]) == -1) {
101            fprintf (stderr, "%s\n", nbd_get_error ());
102            exit (EXIT_FAILURE);
103          }
104
105          /* See if the server provided extra details,
106           * using functions added in 1.4
107           */
108        #if LIBNBD_HAVE_NBD_GET_EXPORT_DESCRIPTION
109          str = nbd_get_canonical_export_name (nbd);
110          if (str)
111            printf ("canonical_name = %s\n", str);
112          free (str);
113          str = nbd_get_export_description (nbd);
114          if (str)
115            printf ("description = %s\n", str);
116          free (str);
117        #endif
118
119          /* Read and print the flags. */
120        #define PRINT_FLAG(flag_fn)                     \
121          flag = flag_fn (nbd);                         \
122          if (flag == -1) {                             \
123            fprintf (stderr, "%s\n", nbd_get_error ()); \
124            exit (EXIT_FAILURE);                        \
125          }                                             \
126          printf (#flag_fn " = %s\n",                   \
127                  flag ? "true" : "false");
128
129          PRINT_FLAG (nbd_can_cache);
130          PRINT_FLAG (nbd_can_df);
131          PRINT_FLAG (nbd_can_flush);
132          PRINT_FLAG (nbd_can_fua);
133          PRINT_FLAG (nbd_can_multi_conn);
134          PRINT_FLAG (nbd_can_trim);
135          PRINT_FLAG (nbd_can_zero);
136        #if LIBNBD_HAVE_NBD_CAN_FAST_ZERO /* Added in 1.2 */
137          PRINT_FLAG (nbd_can_fast_zero);
138        #endif
139          PRINT_FLAG (nbd_is_read_only);
140          PRINT_FLAG (nbd_is_rotational);
141
142          /* Close the libnbd handle. */
143          nbd_close (nbd);
144
145          exit (EXIT_SUCCESS);
146        }
147

AUTHORS

154       Eric Blake
155
156       Richard W.M. Jones
157

COPYRIGHT

159       Copyright Red Hat
160

LICENSE

162       This library is free software; you can redistribute it and/or modify it
163       under the terms of the GNU Lesser General Public License as published
164       by the Free Software Foundation; either version 2 of the License, or
165       (at your option) any later version.
166
167       This library is distributed in the hope that it will be useful, but
168       WITHOUT ANY WARRANTY; without even the implied warranty of
169       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
170       Lesser General Public License for more details.
171
172       You should have received a copy of the GNU Lesser General Public
173       License along with this library; if not, write to the Free Software
174       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
175       02110-1301 USA
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179libnbd-1.16.5                     2023-09-26  nbd_get_canonical_export_name(3)