1 /* Copyright (C) 1995,1996,1998,1999,2000,2001 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, write to the Free
16 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
25 #define HOSTIDFILE "/etc/hostid"
26 #define OLD_HOSTIDFILE "/etc/hostid"
28 #if !defined(_ELIX_LEVEL) || _ELIX_LEVEL >= 2
29 # define OPEN __open64
42 /* Open file for writing. Everybody is allowed to read this file. */
43 fd = OPEN (HOSTIDFILE, O_CREAT|O_WRONLY|O_TRUNC, 0644);
47 written = __write (fd, &id, sizeof (id));
51 return written != sizeof (id) ? -1 : 0;
56 # include <sys/param.h>
58 # include <netinet/in.h>
63 char hostname[MAXHOSTNAMELEN + 1];
66 struct hostent hostbuf, *hp;
72 /* First try to get the ID from a former invocation of sethostid. */
73 fd = OPEN (HOSTIDFILE, O_RDONLY);
76 ssize_t n = __read (fd, &id, sizeof (id));
84 /* Getting from the file was not successful. An intelligent guess for
85 a unique number of a host is its IP address. Return this. */
86 if (__gethostname (hostname, MAXHOSTNAMELEN) < 0 || hostname[0] == '\0')
87 /* This also fails. Return and arbitrary value. */
91 buffer = alloca (buflen);
93 /* To get the IP address we need to know the host name. */
94 while (__gethostbyname_r (hostname, &hostbuf, buffer, buflen, &hp, &herr)
97 if (herr != NETDB_INTERNAL || errno != ERANGE)
101 /* Enlarge buffer. */
103 buffer = alloca (buflen);
107 memcpy (&in, hp->h_addr,
108 (int) sizeof (in) < hp->h_length ? sizeof (in) : hp->h_length);
110 /* For the return value to be not exactly the IP address we do some
112 return in.s_addr << 16 | in.s_addr >> 16;