+
−/* getdtablesize() function for platforms that don't have it.
+
−   Copyright (C) 2008-2011 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 inline 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.  */
+
−static int dtablesize;
+
−
+
−int
+
−getdtablesize (void)
+
−{
+
−  if (dtablesize == 0)
+
−    {
+
−      /* We are looking for the number N such that the valid file descriptors
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−         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
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−         internal array that is never freed.
+
−
+
−         The number N can also be obtained as the upper bound for
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−         _getmaxstdio ().  _getmaxstdio () returns the maximum number of open
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−         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;
+
−}
+
−
+
−#endif