/* xgetaname-impl.c -- common implementation of xgethostname and xgetdomainname

   Copyright (C) 1992, 1996, 2000-2001, 2003-2006, 2009-2025 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/>.  */

/* written by Jim Meyering and Paul Eggert */

#include <stdlib.h>

#include <errno.h>

#include <string.h>

#include <unistd.h>

#include "xalloc.h"

/* Return the current host or domain name in malloc'd storage.

   If malloc fails, exit.

   Upon any other failure, return NULL and set errno.  */

char *

XGETANAME (void)

{

  char buf[100];

  idx_t size = sizeof buf;

  char *name = buf;

  char *alloc = NULL;

  while (1)

    {

      /* Use SIZE_1 here rather than SIZE to work around the bug in

         SunOS 5.5's gethostname whereby it NUL-terminates HOSTNAME

         even when the name is as long as the supplied buffer.  */

      idx_t size_1 = size - 1;

      name[size_1] = '\0';

      errno = 0;

      if (GETANAME (name, size_1) == 0)

        {

          /* Check whether the name was possibly truncated; POSIX does not

             specify whether a truncated name is null-terminated.  */

          idx_t actual_size = strlen (name) + 1;

          if (actual_size < size_1)

            return alloc ? alloc : ximemdup (name, actual_size);

          errno = 0;

        }

      free (alloc);

      if (errno != 0 && errno != ENAMETOOLONG && errno != EINVAL

          /* macOS/Darwin does this when SIZE_1 is too small.  */

          && errno != ENOMEM)

        return NULL;

      name = alloc = xpalloc (NULL, &size, 1, -1, 1);

    }

}