1 /* xgethostname.c -- return current hostname with unlimited length
3 Copyright (C) 1992, 1996, 2000-2001, 2003-2006, 2009-2021 Free Software
6 This program is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <https://www.gnu.org/licenses/>. */
19 /* written by Jim Meyering */
24 #include "xgethostname.h"
33 #ifndef INITIAL_HOSTNAME_LENGTH
34 # define INITIAL_HOSTNAME_LENGTH 34
37 /* Return the current hostname in malloc'd storage.
38 If malloc fails, exit.
39 Upon any other failure, return NULL and set errno. */
43 char *hostname
= NULL
;
44 size_t size
= INITIAL_HOSTNAME_LENGTH
;
48 /* Use SIZE_1 here rather than SIZE to work around the bug in
49 SunOS 5.5's gethostname whereby it NUL-terminates HOSTNAME
50 even when the name is as long as the supplied buffer. */
53 hostname
= x2realloc (hostname
, &size
);
55 hostname
[size_1
- 1] = '\0';
58 if (gethostname (hostname
, size_1
) == 0)
60 if (! hostname
[size_1
- 1])
63 else if (errno
!= 0 && errno
!= ENAMETOOLONG
&& errno
!= EINVAL
64 /* OSX/Darwin does this when the buffer is not large enough */
67 int saved_errno
= errno
;
74 /* Shrink HOSTNAME before returning it. */
76 size_t actual_size
= strlen (hostname
) + 1;
77 if (actual_size
< size
)
79 char *shrinked_hostname
= realloc (hostname
, actual_size
);
80 if (shrinked_hostname
!= NULL
)
81 hostname
= shrinked_hostname
;