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/* xgetaname-impl.c -- common implementation of xgethostname and xgetdomainname
Copyright (C) 1992, 1996, 2000-2001, 2003-2006, 2009-2021 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/>. */
/* 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);
}
}
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