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