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/* Copyright (C) 1995,1996,1998,1999,2000,2001 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, write to the Free

   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA

   02111-1307 USA.  */

#include <alloca.h>

#include <errno.h>

#include <fcntl.h>

#include <unistd.h>

#include <netdb.h>

#define HOSTIDFILE "/etc/hostid"

#define OLD_HOSTIDFILE "/etc/hostid"

#if !defined(_ELIX_LEVEL) || _ELIX_LEVEL >= 2

# define OPEN __open64

#else

# define OPEN __open

#endif

#ifdef SET_PROCEDURE

int

sethostid (id)

     long int id;

{

  int fd;

  ssize_t written;

  /* Open file for writing.  Everybody is allowed to read this file.  */

  fd = OPEN (HOSTIDFILE, O_CREAT|O_WRONLY|O_TRUNC, 0644);

  if (fd < 0)

    return -1;

  written = __write (fd, &id, sizeof (id));

  __close (fd);

  return written != sizeof (id) ? -1 : 0;

}

#else

# include <string.h>

# include <sys/param.h>

# include <netdb.h>

# include <netinet/in.h>

long int

gethostid ()

{

  char hostname[MAXHOSTNAMELEN + 1];

  size_t buflen;

  char *buffer;

  struct hostent hostbuf, *hp;

  unsigned long int id;

  struct in_addr in;

  int herr;

  int fd;

  /* First try to get the ID from a former invocation of sethostid.  */

  fd = OPEN (HOSTIDFILE, O_RDONLY);

  if (fd >= 0)

    {

      ssize_t n = __read (fd, &id, sizeof (id));

      __close (fd);

      if (n == sizeof (id))

        return id;

    }

  /* Getting from the file was not successful.  An intelligent guess for

     a unique number of a host is its IP address.  Return this.  */

  if (__gethostname (hostname, MAXHOSTNAMELEN) < 0 || hostname[0] == '\0')

    /* This also fails.  Return and arbitrary value.  */

    return 0;

  buflen = 1024;

  buffer = alloca (buflen);

  /* To get the IP address we need to know the host name.  */

  while (__gethostbyname_r (hostname, &hostbuf, buffer, buflen, &hp, &herr)

         != 0

         || hp == NULL)

    if (herr != NETDB_INTERNAL || errno != ERANGE)

      return 0;

    else

      {

        /* Enlarge buffer.  */

        buflen *= 2;

        buffer = alloca (buflen);

      }

  in.s_addr = 0;

  memcpy (&in, hp->h_addr,

          (int) sizeof (in) < hp->h_length ? sizeof (in) : hp->h_length);

  /* For the return value to be not exactly the IP address we do some

     bit fiddling.  */

  return in.s_addr << 16 | in.s_addr >> 16;

}

#endif