1nbd_connect_unix(3)                 LIBNBD                 nbd_connect_unix(3)
2
3
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NAME

6       nbd_connect_unix - connect to NBD server over a Unix domain socket
7

SYNOPSIS

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

DESCRIPTION

15       Connect (synchronously) over the named Unix domain socket
16       ("unixsocket") to an NBD server running on the same machine.  This call
17       returns when the connection has been made.
18

RETURN VALUE

20       If the call is successful the function returns 0.
21

ERRORS

23       On error "-1" is returned.
24
25       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
26       of the error.
27
28       The following parameters must not be NULL: "h", "unixsocket".  For more
29       information see "Non-NULL parameters" in libnbd(3).
30

HANDLE STATE

32       The handle must be newly created, otherwise this call will return an
33       error.
34

VERSION

36       This function first appeared in libnbd 1.0.
37
38       If you need to test if this function is available at compile time check
39       if the following macro is defined:
40
41        #define LIBNBD_HAVE_NBD_CONNECT_UNIX 1
42

EXAMPLE

44       This example is also available as examples/fetch-first-sector.c in the
45       libnbd source code.
46
47        /* This example shows how to connect to an NBD server
48         * and fetch and print the first sector (usually the
49         * boot sector or partition table or filesystem
50         * superblock).
51         *
52         * You can test it with nbdkit like this:
53         *
54         * nbdkit -U - floppy . \
55         *   --run './fetch-first-sector $unixsocket'
56         *
57         * The nbdkit floppy plugin creates an MBR disk so the
58         * first sector is the partition table.
59         */
60
61        #include <stdio.h>
62        #include <stdlib.h>
63
64        #include <libnbd.h>
65
66        int
67        main (int argc, char *argv[])
68        {
69          struct nbd_handle *nbd;
70          char buf[512];
71          FILE *pp;
72
73          if (argc != 2) {
74            fprintf (stderr, "%s socket\n", argv[0]);
75            exit (EXIT_FAILURE);
76          }
77
78          /* Create the libnbd handle. */
79          nbd = nbd_create ();
80          if (nbd == NULL) {
81            fprintf (stderr, "%s\n", nbd_get_error ());
82            exit (EXIT_FAILURE);
83          }
84
85          /* Connect to the NBD server over a
86           * Unix domain socket.
87           */
88          if (nbd_connect_unix (nbd, argv[1]) == -1) {
89            fprintf (stderr, "%s\n", nbd_get_error ());
90            exit (EXIT_FAILURE);
91          }
92
93          /* Read the first sector synchronously. */
94          if (nbd_pread (nbd, buf, sizeof buf, 0, 0) == -1) {
95            fprintf (stderr, "%s\n", nbd_get_error ());
96            exit (EXIT_FAILURE);
97          }
98
99          /* Close the libnbd handle. */
100          nbd_close (nbd);
101
102          /* Print the first sector. */
103          pp = popen ("hexdump -C", "w");
104          if (pp == NULL) {
105            perror ("popen: hexdump");
106            exit (EXIT_FAILURE);
107          }
108          fwrite (buf, sizeof buf, 1, pp);
109          pclose (pp);
110
111          exit (EXIT_SUCCESS);
112        }
113

SEE ALSO

115       nbd_aio_connect_unix(3), nbd_create(3), libnbd(3).
116

AUTHORS

118       Eric Blake
119
120       Richard W.M. Jones
121

123       Copyright (C) 2019-2021 Red Hat Inc.
124

LICENSE

126       This library is free software; you can redistribute it and/or modify it
127       under the terms of the GNU Lesser General Public License as published
128       by the Free Software Foundation; either version 2 of the License, or
129       (at your option) any later version.
130
131       This library is distributed in the hope that it will be useful, but
132       WITHOUT ANY WARRANTY; without even the implied warranty of
133       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
134       Lesser General Public License for more details.
135
136       You should have received a copy of the GNU Lesser General Public
137       License along with this library; if not, write to the Free Software
138       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
139       02110-1301 USA
140
141
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143libnbd-1.14.2                     2023-01-03               nbd_connect_unix(3)
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