+
−/* Copy a file descriptor, applying specific flags.
+
−   Copyright (C) 2009-2013 Free Software Foundation, Inc.
+
−
+
−   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 2, 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>
+
−
+
−#include <errno.h>
+
−#include <fcntl.h>
+
−#include <limits.h>
+
−
+
−#include "binary-io.h"
+
−
+
−int
+
−dup3 (int oldfd, int newfd, int flags)
+
−{
+
−#if HAVE_DUP3
+
−# undef dup3
+
−  /* Try the system call first, if it exists.  (We may be running with a glibc
+
−     that has the function but with an older kernel that lacks it.)  */
+
−  {
+
−    /* Cache the information whether the system call really exists.  */
+
−    static int have_dup3_really; /* 0 = unknown, 1 = yes, -1 = no */
+
−    if (have_dup3_really >= 0)
+
−      {
+
−        int result = dup3 (oldfd, newfd, flags);
+
−        if (!(result < 0 && errno == ENOSYS))
+
−          {
+
−            have_dup3_really = 1;
+
−# if REPLACE_FCHDIR
+
−            if (0 <= result)
+
−              result = _gl_register_dup (oldfd, newfd);
+
−# endif
+
−            return result;
+
−          }
+
−        have_dup3_really = -1;
+
−      }
+
−  }
+
−#endif
+
−
+
−  if (newfd < 0 || newfd >= getdtablesize () || fcntl (oldfd, F_GETFD) == -1)
+
−    {
+
−      errno = EBADF;
+
−      return -1;
+
−    }
+
−
+
−  if (newfd == oldfd)
+
−    {
+
−      errno = EINVAL;
+
−      return -1;
+
−    }
+
−
+
−  /* Check the supported flags.
+
−     Note that O_NONBLOCK is not supported, because setting it on newfd
+
−     would implicitly also set it on oldfd.  */
+
−  if ((flags & ~(O_CLOEXEC | O_BINARY | O_TEXT)) != 0)
+
−    {
+
−      errno = EINVAL;
+
−      return -1;
+
−    }
+
−
+
−  if (flags & O_CLOEXEC)
+
−    {
+
−      int result;
+
−      close (newfd);
+
−      result = fcntl (oldfd, F_DUPFD_CLOEXEC, newfd);
+
−      if (newfd < result)
+
−        {
+
−          close (result);
+
−          errno = EIO;
+
−          result = -1;
+
−        }
+
−      if (result < 0)
+
−        return -1;
+
−    }
+
−  else if (dup2 (oldfd, newfd) < 0)
+
−    return -1;
+
−
+
−#if O_BINARY
+
−  if (flags & O_BINARY)
+
−    set_binary_mode (newfd, O_BINARY);
+
−  else if (flags & O_TEXT)
+
−    set_binary_mode (newfd, O_TEXT);
+
−#endif
+
−
+
−  return newfd;
+
−}