1 // SPDX-License-Identifier: CDDL-1.0
2 /*
3 * CDDL HEADER START
4 *
5 * The contents of this file are subject to the terms of the
6 * Common Development and Distribution License (the "License").
7 * You may not use this file except in compliance with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or https://opensource.org/licenses/CDDL-1.0.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22
23 /*
24 * Copyright (c) 2020, Georgy Yakovlev. All rights reserved.
25 */
26
27 #include <errno.h>
28 #include <fcntl.h>
29 #include <getopt.h>
30 #include <inttypes.h>
31 #include <limits.h>
32 #include <stdint.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include <sys/stat.h>
37 #include <time.h>
38 #include <unistd.h>
39
40 static __attribute__((noreturn)) void
usage(void)41 usage(void)
42 {
43 (void) fprintf(stderr,
44 "usage: zgenhostid [-fh] [-o path] [value]\n\n"
45 " -f\t\t force hostid file write\n"
46 " -h\t\t print this usage and exit\n"
47 " -o <filename>\t write hostid to this file\n\n"
48 "If hostid file is not present, store a hostid in it.\n"
49 "The optional value should be an 8-digit hex number between"
50 " 1 and 2^32-1.\n"
51 "If the value is 0 or no value is provided, a random one"
52 " will be generated.\n"
53 "The value must be unique among your systems.\n");
54 exit(EXIT_FAILURE);
55 }
56
57 int
main(int argc,char ** argv)58 main(int argc, char **argv)
59 {
60 /* default file path, can be optionally set by user */
61 const char *path = "/etc/hostid";
62 /* holds converted user input or lrand48() generated value */
63 unsigned long input_i = 0;
64
65 int opt;
66 int force_fwrite = 0;
67 while ((opt = getopt_long(argc, argv, "fo:h?", 0, 0)) != -1) {
68 switch (opt) {
69 case 'f':
70 force_fwrite = 1;
71 break;
72 case 'o':
73 path = optarg;
74 break;
75 case 'h':
76 case '?':
77 usage();
78 }
79 }
80
81 char *in_s = argv[optind];
82 if (in_s != NULL) {
83 /* increment pointer by 2 if string is 0x prefixed */
84 if (strncasecmp("0x", in_s, 2) == 0) {
85 in_s += 2;
86 }
87
88 /* need to be exactly 8 characters */
89 const char *hex = "0123456789abcdefABCDEF";
90 if (strlen(in_s) != 8 || strspn(in_s, hex) != 8) {
91 fprintf(stderr, "%s\n", strerror(ERANGE));
92 usage();
93 }
94
95 input_i = strtoul(in_s, NULL, 16);
96 if (errno != 0) {
97 perror("strtoul");
98 exit(EXIT_FAILURE);
99 }
100
101 if (input_i > UINT32_MAX) {
102 fprintf(stderr, "%s\n", strerror(ERANGE));
103 usage();
104 }
105 }
106
107 struct stat fstat;
108 if (force_fwrite == 0 && stat(path, &fstat) == 0 &&
109 S_ISREG(fstat.st_mode)) {
110 fprintf(stderr, "%s: %s\n", path, strerror(EEXIST));
111 exit(EXIT_FAILURE);
112 }
113
114 /*
115 * generate if not provided by user
116 * also handle unlikely zero return from lrand48()
117 */
118 while (input_i == 0) {
119 srand48(getpid() ^ time(NULL));
120 input_i = lrand48();
121 }
122
123 FILE *fp = fopen(path, "wb");
124 if (!fp) {
125 perror("fopen");
126 exit(EXIT_FAILURE);
127 }
128
129 /*
130 * we need just 4 bytes in native endianness
131 * not using sethostid() because it may be missing or just a stub
132 */
133 uint32_t hostid = input_i;
134 int written = fwrite(&hostid, 1, 4, fp);
135 if (written != 4) {
136 perror("fwrite");
137 exit(EXIT_FAILURE);
138 }
139
140 fclose(fp);
141 exit(EXIT_SUCCESS);
142 }
143