lib/xgethostname.c

   1 /* xgethostname.c -- return current hostname with unlimited length
   2    Copyright (C) 1992, 1996, 2000, 2001 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* written by Jim Meyering */
  19
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include <sys/types.h>
  25
  26 #include <errno.h>
  27 #ifndef errno
  28 extern int errno;
  29 #endif
  30
  31 #include "error.h"
  32 #include "xalloc.h"
  33
  34 #ifndef ENAMETOOLONG
  35 # define ENAMETOOLONG 9999
  36 #endif
  37
  38 #ifndef EXIT_FAILURE
  39 # define EXIT_FAILURE 1
  40 #endif
  41
  42 int gethostname ();
  43
  44 #ifndef INITIAL_HOSTNAME_LENGTH
  45 # define INITIAL_HOSTNAME_LENGTH 34
  46 #endif
  47
  48 char *
  49 xgethostname ()
  50 {
  51   char *hostname;
  52   size_t size;
  53
  54   size = INITIAL_HOSTNAME_LENGTH;
  55   /* Use size + 1 here rather than size to work around the bug
  56      in SunOS5.5's gethostname whereby it NUL-terminates HOSTNAME
  57      even when the name is longer than the supplied buffer.  */
  58   hostname = xmalloc (size + 1);
  59   while (1)
  60     {
  61       int k = size - 1;
  62       int err;
  63
  64       errno = 0;
  65       hostname[k] = '\0';
  66       err = gethostname (hostname, size);
  67       if (err >= 0 && hostname[k] == '\0')
  68         break;
  69       else if (err < 0 && errno != ENAMETOOLONG && errno != 0)
  70         error (EXIT_FAILURE, errno, "gethostname");
  71       size *= 2;
  72       hostname = xrealloc (hostname, size + 1);
  73     }
  74
  75   return hostname;
  76 }