142 lines
3.4 KiB
C
142 lines
3.4 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2020, Georgy Yakovlev. All rights reserved.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <getopt.h>
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#include <inttypes.h>
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#include <limits.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <time.h>
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#include <unistd.h>
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static _Noreturn void
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usage(void)
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{
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(void) fprintf(stderr,
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"usage: zgenhostid [-fh] [-o path] [value]\n\n"
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" -f\t\t force hostid file write\n"
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" -h\t\t print this usage and exit\n"
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" -o <filename>\t write hostid to this file\n\n"
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"If hostid file is not present, store a hostid in it.\n"
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"The optional value should be an 8-digit hex number between"
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" 1 and 2^32-1.\n"
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"If the value is 0 or no value is provided, a random one"
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" will be generated.\n"
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"The value must be unique among your systems.\n");
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exit(EXIT_FAILURE);
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}
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int
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main(int argc, char **argv)
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{
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/* default file path, can be optionally set by user */
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const char *path = "/etc/hostid";
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/* holds converted user input or lrand48() generated value */
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unsigned long input_i = 0;
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int opt;
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int force_fwrite = 0;
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while ((opt = getopt_long(argc, argv, "fo:h?", 0, 0)) != -1) {
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switch (opt) {
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case 'f':
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force_fwrite = 1;
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break;
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case 'o':
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path = optarg;
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break;
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case 'h':
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case '?':
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usage();
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}
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}
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char *in_s = argv[optind];
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if (in_s != NULL) {
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/* increment pointer by 2 if string is 0x prefixed */
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if (strncasecmp("0x", in_s, 2) == 0) {
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in_s += 2;
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}
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/* need to be exactly 8 characters */
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const char *hex = "0123456789abcdefABCDEF";
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if (strlen(in_s) != 8 || strspn(in_s, hex) != 8) {
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fprintf(stderr, "%s\n", strerror(ERANGE));
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usage();
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}
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input_i = strtoul(in_s, NULL, 16);
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if (errno != 0) {
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perror("strtoul");
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exit(EXIT_FAILURE);
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}
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if (input_i > UINT32_MAX) {
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fprintf(stderr, "%s\n", strerror(ERANGE));
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usage();
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}
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}
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struct stat fstat;
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if (force_fwrite == 0 && stat(path, &fstat) == 0 &&
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S_ISREG(fstat.st_mode)) {
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fprintf(stderr, "%s: %s\n", path, strerror(EEXIST));
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exit(EXIT_FAILURE);
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}
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/*
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* generate if not provided by user
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* also handle unlikely zero return from lrand48()
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*/
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while (input_i == 0) {
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srand48(getpid() ^ time(NULL));
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input_i = lrand48();
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}
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FILE *fp = fopen(path, "wb");
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if (!fp) {
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perror("fopen");
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exit(EXIT_FAILURE);
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}
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/*
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* we need just 4 bytes in native endianness
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* not using sethostid() because it may be missing or just a stub
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*/
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uint32_t hostid = input_i;
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int written = fwrite(&hostid, 1, 4, fp);
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if (written != 4) {
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perror("fwrite");
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exit(EXIT_FAILURE);
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}
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fclose(fp);
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exit(EXIT_SUCCESS);
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}
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