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
32static unsigned long
33get_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
58unsigned long
59get_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