/* Duplicate a file descriptor to a given number, with flags.  Hurd version.

   Copyright (C) 1991-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; see the file COPYING.LIB.  If

   not, see <http://www.gnu.org/licenses/>.  */

#include <errno.h>

#include <fcntl.h>

#include <unistd.h>

#include <hurd.h>

#include <hurd/fd.h>

/* Duplicate FD to FD2, closing the old FD2 and making FD2 be

   open on the same file as FD is, and setting FD2's flags according to FLAGS.

   Return FD2 or -1.  */

int

__dup3 (int fd, int fd2, int flags)

{

  struct hurd_fd *d;

  /* Both passing flags different from O_CLOEXEC and FD2 being the same as FD

     are invalid.  */

  if ((flags & ~O_CLOEXEC

       || fd2 == fd)

      /* ... with the exception in case that dup2 behavior is requested: if FD

	 is valid and FD2 is already the same then just return it.  */

      && ! (flags == -1

	    && fd2 == fd))

    return __hurd_fail (EINVAL);

  /* Extract the ports and flags from FD.  */

  d = _hurd_fd_get (fd);

  if (d == NULL)

    return __hurd_fail (EBADF);

  HURD_CRITICAL_BEGIN;

  __spin_lock (&d->port.lock);

  if (d->port.port == MACH_PORT_NULL)

    {

      __spin_unlock (&d->port.lock);

      fd2 = __hurd_fail (EBADF);

    }

  else if (fd2 == fd)

    __spin_unlock (&d->port.lock);

  else

    {

      struct hurd_userlink ulink, ctty_ulink;

      int d_flags = d->flags;

      io_t ctty = _hurd_port_get (&d->ctty, &ctty_ulink);

      io_t port = _hurd_port_locked_get (&d->port, &ulink); /* Unlocks D.  */

      if (fd2 < 0)

	fd2 = __hurd_fail (EBADF);

      else

	{

	  /* Get a hold of the destination descriptor.  */

	  struct hurd_fd *d2;

	  __mutex_lock (&_hurd_dtable_lock);

	  if (fd2 >= _hurd_dtablesize)

	    {

	      /* The table is not large enough to hold the destination

		 descriptor.  Enlarge it as necessary to allocate this

		 descriptor.  */

	      __mutex_unlock (&_hurd_dtable_lock);

	      d2 = _hurd_alloc_fd (NULL, fd2);

	      if (d2)

		__spin_unlock (&d2->port.lock);

	      __mutex_lock (&_hurd_dtable_lock);

	    }

	  else

	    {

	      d2 = _hurd_dtable[fd2];

	      if (d2 == NULL)

		{

		  /* Must allocate a new one.  We don't initialize the port

		     cells with this call so that if it fails (out of

		     memory), we will not have already added user

		     references for the ports, which we would then have to

		     deallocate.  */

		  d2 = _hurd_dtable[fd2] = _hurd_new_fd (MACH_PORT_NULL,

							 MACH_PORT_NULL);

		}

	    }

	  __mutex_unlock (&_hurd_dtable_lock);

	  if (d2 == NULL)

	    {

	      fd2 = -1;

	      if (errno == EINVAL)

		errno = EBADF;	/* POSIX.1-1990 6.2.1.2 ll 54-55.  */

	    }

	  else

	    {

	      /* Give the ports each a user ref for the new descriptor.  */

	      __mach_port_mod_refs (__mach_task_self (), port,

				    MACH_PORT_RIGHT_SEND, 1);

	      if (ctty != MACH_PORT_NULL)

		__mach_port_mod_refs (__mach_task_self (), ctty,

				      MACH_PORT_RIGHT_SEND, 1);

	      /* Install the ports and flags in the new descriptor slot.  */

	      __spin_lock (&d2->port.lock);

	      if (flags & O_CLOEXEC)

		d2->flags = d_flags | FD_CLOEXEC;

	      else

		/* dup clears FD_CLOEXEC.  */

		d2->flags = d_flags & ~FD_CLOEXEC;

	      _hurd_port_set (&d2->ctty, ctty);

	      _hurd_port_locked_set (&d2->port, port); /* Unlocks D2.  */

	    }

	}

      _hurd_port_free (&d->port, &ulink, port);

      if (ctty != MACH_PORT_NULL)

	_hurd_port_free (&d->ctty, &ctty_ulink, port);

    }

  HURD_CRITICAL_END;

  return fd2;

}

libc_hidden_def (__dup3)

weak_alias (__dup3, dup3)