98 lines
2.5 KiB
C
98 lines
2.5 KiB
C
/* Copyright (C) 1995, 1996 Free Software Foundation, Inc.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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#define HOSTIDFILE "/var/adm/hostid"
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#ifdef SET_PROCEDURE
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int
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sethostid (id)
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long int id;
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{
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int fd;
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ssize_t written;
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/* Test for appropriate rights to set host ID. */
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if (__libc_enable_secure)
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{
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__set_errno (EPERM);
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return -1;
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}
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/* Open file for writing. Everybody is allowed to read this file. */
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fd = __open (HOSTIDFILE, O_CREAT|O_WRONLY, 0644);
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if (fd < 0)
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return -1;
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written = __write (fd, &id, sizeof (id));
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__close (fd);
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return written != sizeof (id) ? -1 : 0;
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}
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#else
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# include <string.h>
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# include <sys/param.h>
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# include <resolv/netdb.h>
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# include <netinet/in.h>
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long int
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gethostid ()
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{
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char hostname[MAXHOSTNAMELEN + 1];
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struct hostent *hp;
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unsigned long id;
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struct in_addr in;
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int fd;
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/* First try to get the ID from a former invocation of sethostid. */
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fd = __open (HOSTIDFILE, O_RDONLY);
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if (fd >= 0)
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{
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ssize_t n = __read (fd, &id, sizeof (id));
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__close (fd);
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if (n == sizeof (id))
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return id;
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}
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/* Getting from the file was not succesful. An intelligent guess for
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a unique number of a host is its IP address. Return this. */
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if (gethostname (hostname, MAXHOSTNAMELEN) < 0 || hostname[0] == '\0')
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/* This also fails. Return and arbitrary value. */
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return 0;
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/* To get the IP address we need to know the host name. */
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hp = gethostbyname (hostname);
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if (hp == NULL)
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return 0;
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in.s_addr = 0;
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memcpy (&in, hp->h_addr,
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(int) sizeof (in) < hp->h_length ? sizeof (in) : hp->h_length);
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/* For the return value to be not exactly the IP address we do some
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bit fiddling. */
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return in.s_addr << 16 | in.s_addr >> 16;
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}
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#endif
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