1/* xgethostname.c -- return current hostname with unlimited length 2 3 Copyright (C) 1992, 1996, 2000-2001, 2003-2006, 2009-2010 Free Software 4 Foundation, Inc. 5 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. 10 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. 15 16 You should have received a copy of the GNU General Public License 17 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 18 19/* written by Jim Meyering */ 20 21#include <config.h> 22 23/* Specification. */ 24#include "xgethostname.h" 25 26#include <stdlib.h> 27#include <errno.h> 28#include <unistd.h> 29 30#include "xalloc.h" 31 32#ifndef INITIAL_HOSTNAME_LENGTH 33# define INITIAL_HOSTNAME_LENGTH 34 34#endif 35 36/* Return the current hostname in malloc'd storage. 37 If malloc fails, exit. 38 Upon any other failure, return NULL and set errno. */ 39char * 40xgethostname (void) 41{ 42 char *hostname = NULL; 43 size_t size = INITIAL_HOSTNAME_LENGTH; 44 45 while (1) 46 { 47 /* Use SIZE_1 here rather than SIZE to work around the bug in 48 SunOS 5.5's gethostname whereby it NUL-terminates HOSTNAME 49 even when the name is as long as the supplied buffer. */ 50 size_t size_1; 51 52 hostname = x2realloc (hostname, &size); 53 size_1 = size - 1; 54 hostname[size_1 - 1] = '\0'; 55 errno = 0; 56 57 if (gethostname (hostname, size_1) == 0) 58 { 59 if (! hostname[size_1 - 1]) 60 break; 61 } 62 else if (errno != 0 && errno != ENAMETOOLONG && errno != EINVAL 63 /* OSX/Darwin does this when the buffer is not large enough */ 64 && errno != ENOMEM) 65 { 66 int saved_errno = errno; 67 free (hostname); 68 errno = saved_errno; 69 return NULL; 70 } 71 } 72 73 return hostname; 74} 75