1 /* xgetaname-impl.c -- common implementation of xgethostname and xgetdomainname 2 3 Copyright (C) 1992, 1996, 2000-2001, 2003-2006, 2009-2021 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 <https://www.gnu.org/licenses/>. */ 18 19 /* written by Jim Meyering and Paul Eggert */ 20 21 #include <stdlib.h> 22 #include <errno.h> 23 #include <string.h> 24 #include <unistd.h> 25 26 #include "xalloc.h" 27 28 /* Return the current host or domain name in malloc'd storage. 29 If malloc fails, exit. 30 Upon any other failure, return NULL and set errno. */ 31 char * 32 XGETANAME (void) /* */ 33 { 34 char buf[100]; 35 idx_t size = sizeof buf; 36 char *name = buf; 37 char *alloc = NULL; 38 39 while (1) 40 { 41 /* Use SIZE_1 here rather than SIZE to work around the bug in 42 SunOS 5.5's gethostname whereby it NUL-terminates HOSTNAME 43 even when the name is as long as the supplied buffer. */ 44 idx_t size_1 = size - 1; 45 name[size_1] = '\0'; 46 errno = 0; 47 if (GETANAME (name, size_1) == 0) 48 { 49 /* Check whether the name was possibly truncated; POSIX does not 50 specify whether a truncated name is null-terminated. */ 51 idx_t actual_size = strlen (name) + 1; 52 if (actual_size < size_1) 53 return alloc ? alloc : ximemdup (name, actual_size); 54 errno = 0; 55 } 56 free (alloc); 57 if (errno != 0 && errno != ENAMETOOLONG && errno != EINVAL 58 /* macOS/Darwin does this when SIZE_1 is too small. */ 59 && errno != ENOMEM) 60 return NULL; 61 name = alloc = xpalloc (NULL, &size, 1, -1, 1); 62 } 63 }