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/* xgetdomainname.c -- Return the NIS domain name, without size limitations.
Copyright (C) 1992, 1996, 2000-2001, 2003-2004, 2006, 2008-2021 Free
Software Foundation, Inc.
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 of the License, 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, see <https://www.gnu.org/licenses/>. */
/* Based on xgethostname.c, written by Jim Meyering. */
#include <config.h>
/* Specification. */
#include "xgetdomainname.h"
/* Get getdomainname. */
#include <unistd.h>
/* Get errno. */
#include <errno.h>
/* Get strlen. */
#include <string.h>
/* Get free. */
#include <stdlib.h>
#include "xalloc.h"
#ifndef INITIAL_DOMAINNAME_LENGTH
# define INITIAL_DOMAINNAME_LENGTH 34
#endif
/* Return the NIS domain name of the machine, in malloc'd storage.
WARNING! The NIS domain name is unrelated to the fully qualified host name
of the machine. It is also unrelated to email addresses.
WARNING! The NIS domain name is usually the empty string or "(none)" when
not using NIS.
If malloc fails, exit.
Upon any other failure, set errno and return NULL. */
char *
xgetdomainname (void)
{
char *domainname;
size_t size;
size = INITIAL_DOMAINNAME_LENGTH;
domainname = xmalloc (size);
while (1)
{
int k = size - 1;
int err;
errno = 0;
domainname[k] = '\0';
err = getdomainname (domainname, size);
if (err >= 0 && domainname[k] == '\0')
break;
else if (err < 0 && errno != EINVAL)
{
int saved_errno = errno;
free (domainname);
errno = saved_errno;
return NULL;
}
size *= 2;
domainname = xrealloc (domainname, size);
}
/* Shrink DOMAINNAME before returning it. */
{
size_t actual_size = strlen (domainname) + 1;
if (actual_size < size)
{
char *shrinked_domainname = realloc (domainname, actual_size);
if (shrinked_domainname != NULL)
domainname = shrinked_domainname;
}
}
return domainname;
}
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