1  /* Start thread.  Mach version.
       2     Copyright (C) 2000-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library;  if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <assert.h>
      20  #include <errno.h>
      21  #include <string.h>
      22  
      23  #include <mach.h>
      24  
      25  #include <pt-internal.h>
      26  
      27  /* Prepare a wakeup message.  */
      28  static error_t
      29  create_wakeupmsg (struct __pthread *thread)
      30  {
      31    kern_return_t err;
      32  
      33    /* Build wakeup message.  */
      34    thread->wakeupmsg.msgh_bits = MACH_MSGH_BITS (MACH_MSG_TYPE_COPY_SEND, 0);
      35    thread->wakeupmsg.msgh_size = 0;
      36  
      37    err = __mach_port_allocate (__mach_task_self (), MACH_PORT_RIGHT_RECEIVE,
      38  			      &thread->wakeupmsg.msgh_remote_port);
      39    if (err)
      40      return EAGAIN;
      41  
      42    thread->wakeupmsg.msgh_local_port = MACH_PORT_NULL;
      43    thread->wakeupmsg.msgh_seqno = 0;
      44    thread->wakeupmsg.msgh_id = 0;
      45  
      46    err = __mach_port_insert_right (__mach_task_self (),
      47  				  thread->wakeupmsg.msgh_remote_port,
      48  				  thread->wakeupmsg.msgh_remote_port,
      49  				  MACH_MSG_TYPE_MAKE_SEND);
      50    if (err)
      51      {
      52        __mach_port_destroy (__mach_task_self (),
      53  			   thread->wakeupmsg.msgh_remote_port);
      54        return EAGAIN;
      55      }
      56  
      57    /* No need to queue more than one wakeup message on this port.  */
      58    __mach_port_set_qlimit (__mach_task_self (),
      59  			  thread->wakeupmsg.msgh_remote_port, 1);
      60  
      61    return 0;
      62  }
      63  
      64  /* Allocate any resources for THREAD.  The new kernel thread should not
      65     be eligible to be scheduled.  */
      66  int
      67  __pthread_thread_alloc (struct __pthread *thread)
      68  {
      69    static int do_create;
      70    error_t err;
      71  
      72    err = create_wakeupmsg (thread);
      73    if (err)
      74      return err;
      75  
      76    if (!do_create)
      77      {
      78        assert (__pthread_total == 0);
      79        thread->kernel_thread = __mach_thread_self ();
      80        do_create = 1;
      81      }
      82    else
      83      {
      84        err = __thread_create (__mach_task_self (), &thread->kernel_thread);
      85        if (err)
      86  	{
      87  	  __mach_port_destroy (__mach_task_self (),
      88  			       thread->wakeupmsg.msgh_remote_port);
      89  	  return EAGAIN;
      90  	}
      91      }
      92  
      93    return 0;
      94  }