text: /* getdtablesize() function for platforms that don't have it.
     Copyright (C) 2008-2013 Free Software Foundation, Inc.
     Written by Bruno Haible <bruno@clisp.org>, 2008.
  
     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 <http://www.gnu.org/licenses/>.  */
  
  #include <config.h>
  
  /* Specification.  */
  #include <unistd.h>
  
  #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  
  # include <stdio.h>
  
  # include "msvc-inval.h"
  
  # if HAVE_MSVC_INVALID_PARAMETER_HANDLER
  static int
  _setmaxstdio_nothrow (int newmax)
  {
    int result;
  
    TRY_MSVC_INVAL
      {
        result = _setmaxstdio (newmax);
      }
    CATCH_MSVC_INVAL
      {
        result = -1;
      }
    DONE_MSVC_INVAL;
  
    return result;
  }
  #  define _setmaxstdio _setmaxstdio_nothrow
  # endif
  
  /* Cache for the previous getdtablesize () result.  Safe to cache because
     Windows also lacks setrlimit.  */
  static int dtablesize;
  
  int
  getdtablesize (void)
  {
    if (dtablesize == 0)
      {
        /* We are looking for the number N such that the valid file descriptors
           are 0..N-1.  It can be obtained through a loop as follows:
             {
               int fd;
               for (fd = 3; fd < 65536; fd++)
                 if (dup2 (0, fd) == -1)
                   break;
               return fd;
             }
           On Windows XP, the result is 2048.
           The drawback of this loop is that it allocates memory for a libc
           internal array that is never freed.
  
           The number N can also be obtained as the upper bound for
           _getmaxstdio ().  _getmaxstdio () returns the maximum number of open
           FILE objects.  The sanity check in _setmaxstdio reveals the maximum
           number of file descriptors.  This too allocates memory, but it is
           freed when we call _setmaxstdio with the original value.  */
        int orig_max_stdio = _getmaxstdio ();
        unsigned int bound;
        for (bound = 0x10000; _setmaxstdio (bound) < 0; bound = bound / 2)
          ;
        _setmaxstdio (orig_max_stdio);
        dtablesize = bound;
      }
    return dtablesize;
  }
  
  #elif HAVE_GETDTABLESIZE
  
  # include <sys/resource.h>
  # undef getdtablesize
  
  int
  rpl_getdtablesize(void)
  {
    /* To date, this replacement is only compiled for Cygwin 1.7.25,
       which auto-increased the RLIMIT_NOFILE soft limit until it
       hits the compile-time constant hard limit of 3200.  Although
       that version of cygwin supported a child process inheriting
       a smaller soft limit, the smaller limit is not enforced, so
       we might as well just report the hard limit.  */
    struct rlimit lim;
    if (!getrlimit (RLIMIT_NOFILE, &lim) && lim.rlim_max != RLIM_INFINITY)
      return lim.rlim_max;
    return getdtablesize ();
  }
  
  #endif
  