glibc/sysdeps/mach/htl/pt-thread-alloc.c

/* Start thread.  Mach version.
   Copyright (C) 2000-2018 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 Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If
   not, see <http://www.gnu.org/licenses/>.  */

#include <assert.h>
#include <errno.h>
#include <string.h>

#include <mach.h>

#include <pt-internal.h>

/* Prepare a wakeup message.  */
static error_t
create_wakeupmsg (struct __pthread *thread)
{
  kern_return_t err;

  /* Build wakeup message.  */
  thread->wakeupmsg.msgh_bits = MACH_MSGH_BITS (MACH_MSG_TYPE_COPY_SEND, 0);
  thread->wakeupmsg.msgh_size = 0;

  err = __mach_port_allocate (__mach_task_self (), MACH_PORT_RIGHT_RECEIVE,
			      &thread->wakeupmsg.msgh_remote_port);
  if (err)
    return EAGAIN;

  thread->wakeupmsg.msgh_local_port = MACH_PORT_NULL;
  thread->wakeupmsg.msgh_seqno = 0;
  thread->wakeupmsg.msgh_id = 0;

  err = __mach_port_insert_right (__mach_task_self (),
				  thread->wakeupmsg.msgh_remote_port,
				  thread->wakeupmsg.msgh_remote_port,
				  MACH_MSG_TYPE_MAKE_SEND);
  if (err)
    {
      __mach_port_destroy (__mach_task_self (),
			   thread->wakeupmsg.msgh_remote_port);
      return EAGAIN;
    }

  /* No need to queue more than one wakeup message on this port.  */
  __mach_port_set_qlimit (__mach_task_self (),
			  thread->wakeupmsg.msgh_remote_port, 1);

  return 0;
}

/* Allocate any resouces for THREAD.  The new kernel thread should not
   be eligible to be scheduled.  */
int
__pthread_thread_alloc (struct __pthread *thread)
{
  static int do_create;
  error_t err;

  err = create_wakeupmsg (thread);
  if (err)
    return err;

  if (!do_create)
    {
      assert (__pthread_total == 0);
      thread->kernel_thread = __mach_thread_self ();
      do_create = 1;
    }
  else
    {
      err = __thread_create (__mach_task_self (), &thread->kernel_thread);
      if (err)
	{
	  __mach_port_destroy (__mach_task_self (),
			       thread->wakeupmsg.msgh_remote_port);
	  return EAGAIN;
	}
    }

  return 0;
}