1 /*
2 * Copyright (c) 2008, XenSource Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * * Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * * Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * * Neither the name of XenSource Inc. nor the names of its contributors
13 * may be used to endorse or promote products derived from this software
14 * without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
20 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
21 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
22 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
23 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
24 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
25 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
26 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include <stdio.h>
30 #include <errno.h>
31
32 #include "tap-ctl.h"
33
34 int
tap_ctl_blk_major(void)35 tap_ctl_blk_major(void)
36 {
37 FILE *devices;
38 int rv, major;
39
40 devices = fopen("/proc/devices", "r");
41 if (!devices) {
42 rv = -errno;
43 goto out;
44 }
45
46 do {
47 char buf[32], *s;
48 int n, offset;
49
50 s = fgets(buf, sizeof(buf), devices);
51 if (!s)
52 break;
53
54 major = -ENODEV;
55 offset = 0;
56
57 n = sscanf(buf, "%d tapdev%n", &major, &offset);
58 if (n == 1 && offset)
59 break;
60 } while (1);
61
62 rv = major;
63
64 out:
65 if (devices)
66 fclose(devices);
67
68 return rv;
69 }
70