1 /* vi: set sw=4 ts=4: */
3 * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
5 * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
12 #include <sys/types.h>
17 #include <not-cancel.h>
19 #define HOSTID "/etc/hostid"
22 int sethostid(long int new_id)
27 if (geteuid() || getuid())
28 return __set_errno(EPERM);
29 fd = open_not_cancel(HOSTID, O_CREAT|O_WRONLY, 0644);
32 ret = write_not_cancel(fd, &new_id, sizeof(new_id)) == sizeof(new_id) ? 0 : -1;
33 close_not_cancel_no_status (fd);
38 #define _addr(a) (((struct sockaddr_in*)a->ai_addr)->sin_addr.s_addr)
39 long int gethostid(void)
41 char host[HOST_NAME_MAX + 1];
44 /* If hostid was already set then we can return that value.
45 * It is not an error if we cannot read this file. It is not even an
46 * error if we cannot read all the bytes, we just carry on trying...
48 fd = open_not_cancel_2(HOSTID, O_RDONLY);
50 int i = read_not_cancel(fd, &id, sizeof(id));
51 close_not_cancel_no_status(fd);
55 /* Try some methods of returning a unique 32 bit id. Clearly IP
56 * numbers, if on the internet, will have a unique address. If they
57 * are not on the internet then we can return 0 which means they should
58 * really set this number via a sethostid() call. If their hostname
59 * returns the loopback number (i.e. if they have put their hostname
60 * in the /etc/hosts file with 127.0.0.1) then all such hosts will
61 * have a non-unique hostid, but it doesn't matter anyway and
62 * gethostid() will return a non zero number without the need for
66 if (gethostname(host, HOST_NAME_MAX) >= 0 && *host) {
67 struct addrinfo hints, *results, *addr;
68 memset(&hints, 0, sizeof(struct addrinfo));
69 if (!getaddrinfo(host, NULL, &hints, &results)) {
70 for (addr = results; addr; addr = results->ai_next) {
71 /* Just so it doesn't look exactly like the
73 id = _addr(addr) << 16 | _addr(addr) >> 16;
76 freeaddrinfo(results);