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/* A slightly more convenient wrapper for gethostname
Copyright (C) 1996, 1997, 2000, 2005, 2006, 2007 Free Software Foundation, Inc.
Written by Miles Bader <miles@gnu.ai.mit.edu>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 3, or (at
your option) any later version.
This program 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <unistd.h>
#ifdef HAVE_MALLOC_H
# include <malloc.h>
#endif
#if defined(STDC_HEADERS) || defined(HAVE_STDLIB_H)
# include <stdlib.h>
#endif
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
/* Return the name of the localhost. This is just a wrapper for gethostname,
which takes care of allocating a big enough buffer, and caches the result
after the first call (so the result should be copied before modification).
If something goes wrong, 0 is returned, and errno set. */
/* We know longer use static buffers, is to dangerous and
cause subtile bugs. */
char *
localhost (void)
{
char *buf = NULL;
size_t buf_len = 0;
int status = 0;
do
{
char *tmp;
errno = 0;
buf_len += 256; /* Initial guess */
tmp = realloc (buf, buf_len);
if (tmp == NULL)
{
errno = ENOMEM;
free (buf);
return 0;
}
else
buf = tmp;
}
while (((status = gethostname (buf, buf_len)) == 0
&& !memchr (buf, '\0', buf_len))
#ifdef ENAMETOOLONG
|| errno == ENAMETOOLONG
#endif
);
if (status != 0 && errno != 0)
/* gethostname failed, abort. */
{
free (buf);
buf = 0;
}
else
/* Determine FQDN */
{
struct hostent *hp = gethostbyname (buf);
if (hp)
{
struct in_addr addr;
addr.s_addr = *(unsigned int *) hp->h_addr;
hp = gethostbyaddr ((char *) &addr, sizeof (addr), AF_INET);
if (hp)
{
free (buf);
buf = strdup (hp->h_name);
}
}
}
return buf;
}
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