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 http://www.opensolaris.org/os/licensing.
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 /*
23 * Copyright (c) 2020, Georgy Yakovlev. All rights reserved.
24 */
25
26 #include <errno.h>
27 #include <fcntl.h>
28 #include <getopt.h>
29 #include <inttypes.h>
30 #include <limits.h>
31 #include <stdint.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <sys/stat.h>
36 #include <time.h>
37 #include <unistd.h>
38
39 static void usage(void);
40
41 static void
usage(void)42 usage(void)
43 {
44 (void) fprintf(stderr,
45 "usage: zgenhostid [-fh] [-o path] [value]\n\n"
46 " -f\t\t force hostid file write\n"
47 " -h\t\t print this usage and exit\n"
48 " -o <filename>\t write hostid to this file\n\n"
49 "If hostid file is not present, store a hostid in it.\n"
50 "The optional value should be an 8-digit hex number between"
51 " 1 and 2^32-1.\n"
52 "If the value is 0 or no value is provided, a random one"
53 " will be generated.\n"
54 "The value must be unique among your systems.\n");
55 exit(EXIT_FAILURE);
56 /* NOTREACHED */
57 }
58
59 int
main(int argc,char ** argv)60 main(int argc, char **argv)
61 {
62 /* default file path, can be optionally set by user */
63 char path[PATH_MAX] = "/etc/hostid";
64 /* holds converted user input or lrand48() generated value */
65 unsigned long input_i = 0;
66
67 int opt;
68 int pathlen;
69 int force_fwrite = 0;
70 while ((opt = getopt_long(argc, argv, "fo:h?", 0, 0)) != -1) {
71 switch (opt) {
72 case 'f':
73 force_fwrite = 1;
74 break;
75 case 'o':
76 pathlen = snprintf(path, sizeof (path), "%s", optarg);
77 if (pathlen >= sizeof (path)) {
78 fprintf(stderr, "%s\n", strerror(EOVERFLOW));
79 exit(EXIT_FAILURE);
80 } else if (pathlen < 1) {
81 fprintf(stderr, "%s\n", strerror(EINVAL));
82 exit(EXIT_FAILURE);
83 }
84 break;
85 case 'h':
86 case '?':
87 usage();
88 }
89 }
90
91 char *in_s = argv[optind];
92 if (in_s != NULL) {
93 /* increment pointer by 2 if string is 0x prefixed */
94 if (strncasecmp("0x", in_s, 2) == 0) {
95 in_s += 2;
96 }
97
98 /* need to be exactly 8 characters */
99 const char *hex = "0123456789abcdefABCDEF";
100 if (strlen(in_s) != 8 || strspn(in_s, hex) != 8) {
101 fprintf(stderr, "%s\n", strerror(ERANGE));
102 usage();
103 }
104
105 input_i = strtoul(in_s, NULL, 16);
106 if (errno != 0) {
107 perror("strtoul");
108 exit(EXIT_FAILURE);
109 }
110
111 if (input_i > UINT32_MAX) {
112 fprintf(stderr, "%s\n", strerror(ERANGE));
113 usage();
114 }
115 }
116
117 struct stat fstat;
118 if (force_fwrite == 0 && stat(path, &fstat) == 0 &&
119 S_ISREG(fstat.st_mode)) {
120 fprintf(stderr, "%s: %s\n", path, strerror(EEXIST));
121 exit(EXIT_FAILURE);
122 }
123
124 /*
125 * generate if not provided by user
126 * also handle unlikely zero return from lrand48()
127 */
128 while (input_i == 0) {
129 srand48(getpid() ^ time(NULL));
130 input_i = lrand48();
131 }
132
133 FILE *fp = fopen(path, "wb");
134 if (!fp) {
135 perror("fopen");
136 exit(EXIT_FAILURE);
137 }
138
139 /*
140 * we need just 4 bytes in native endianess
141 * not using sethostid() because it may be missing or just a stub
142 */
143 uint32_t hostid = input_i;
144 int written = fwrite(&hostid, 1, 4, fp);
145 if (written != 4) {
146 perror("fwrite");
147 exit(EXIT_FAILURE);
148 }
149
150 fclose(fp);
151 exit(EXIT_SUCCESS);
152 }
153