1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or https://opensource.org/licenses/CDDL-1.0.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 2017, Lawrence Livermore National Security, LLC.
23 */
24
25 #include <fcntl.h>
26 #include <stdlib.h>
27 #include <stdio.h>
28 #include <sys/types.h>
29 #include <sys/stat.h>
30 #include <sys/systeminfo.h>
31
32 static unsigned long
get_spl_hostid(void)33 get_spl_hostid(void)
34 {
35 FILE *f;
36 unsigned long hostid;
37 char *env;
38
39 /*
40 * Allow the hostid to be subverted for testing.
41 */
42 env = getenv("ZFS_HOSTID");
43 if (env)
44 return (strtoull(env, NULL, 0));
45
46 f = fopen("/proc/sys/kernel/spl/hostid", "re");
47 if (!f)
48 return (0);
49
50 if (fscanf(f, "%lx", &hostid) != 1)
51 hostid = 0;
52
53 fclose(f);
54
55 return (hostid);
56 }
57
58 unsigned long
get_system_hostid(void)59 get_system_hostid(void)
60 {
61 unsigned long hostid = get_spl_hostid();
62 uint32_t system_hostid;
63
64 /*
65 * We do not use gethostid(3) because it can return a bogus ID,
66 * depending on the libc and /etc/hostid presence,
67 * and the kernel and userspace must agree.
68 * See comments above hostid_read() in the SPL.
69 */
70 if (hostid == 0) {
71 int fd = open("/etc/hostid", O_RDONLY | O_CLOEXEC);
72 if (fd >= 0) {
73 if (read(fd, &system_hostid, sizeof (system_hostid))
74 != sizeof (system_hostid))
75 hostid = 0;
76 else
77 hostid = system_hostid;
78 (void) close(fd);
79 }
80 }
81
82 return (hostid & HOSTID_MASK);
83 }
84