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