create.c

/*
 * create.c
 *
 * Description:
 * This translation unit implements routines associated with spawning a new
 * thread.
 *
 * --------------------------------------------------------------------------
 *
 *      Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems
 *      Copyright(C) 2008 Jason Schmidlapp
 *
 *      Contact Email: jschmidlapp@users.sourceforge.net
 *
 *
 *      Based upon Pthreads-win32 - POSIX Threads Library for Win32
 *      Copyright(C) 1998 John E. Bossom
 *      Copyright(C) 1999,2005 Pthreads-win32 contributors
 *
 *      Contact Email: rpj@callisto.canberra.edu.au
 *
 *      The original list of contributors to the Pthreads-win32 project
 *      is contained in the file CONTRIBUTORS.ptw32 included with the
 *      source code distribution. The list can also be seen at the
 *      following World Wide Web location:
 *      http://sources.redhat.com/pthreads-win32/contributors.html
 *
 *      This 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 of the License, or (at your option) any later version.
 *
 *      This 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 this library in the file COPYING.LIB;
 *      if not, write to the Free Software Foundation, Inc.,
 *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include "pte_osal.h"
#include <stdio.h>
#include <stdlib.h>

#include "pthread.h"
#include "implement.h"

int
pthread_create (pthread_t * tid,
                const pthread_attr_t * attr,
                void *(*start) (void *), void *arg)
/*
 * ------------------------------------------------------
 * DOCPUBLIC
 *      This function creates a thread running the start function,
 *      passing it the parameter value, 'arg'. The 'attr'
 *      argument specifies optional creation attributes.
 *      The identity of the new thread is returned
 *      via 'tid', which should not be NULL.
 *
 * PARAMETERS
 *      tid
 *              pointer to an instance of pthread_t
 *
 *      attr
 *              optional pointer to an instance of pthread_attr_t
 *
 *      start
 *              pointer to the starting routine for the new thread
 *
 *      arg
 *              optional parameter passed to 'start'
 *
 *
 * DESCRIPTION
 *      This function creates a thread running the start function,
 *      passing it the parameter value, 'arg'. The 'attr'
 *      argument specifies optional creation attributes.
 *      The identity of the new thread is returned
 *      via 'tid', which should not be the NULL pointer.
 *
 * RESULTS
 *              0               successfully created thread,
 *              EINVAL          attr invalid,
 *              EAGAIN          insufficient resources.
 *
 * ------------------------------------------------------
 */
{
  pthread_t thread;
  pte_thread_t * tp;
  register pthread_attr_t a;
  int result = EAGAIN;
  int run = PTE_TRUE;
  ThreadParms *parms = NULL;
  long stackSize;
  int priority = 0;
  pthread_t self;
  pte_osResult osResult;

  /*
   * Before doing anything, check that tid can be stored through
   * without invoking a memory protection error (segfault).
   * Make sure that the assignment below can't be optimised out by the compiler.
   * This is assured by conditionally assigning *tid again at the end.
   */
  if (tid != NULL)
    {
      *tid = 0;
    }

  if (attr != NULL)
    {
      a = *attr;
    }
  else
    {
      a = NULL;
    }

  if ((thread = pte_new ()) == 0)
    {
      goto FAIL0;
    }

  tp = (pte_thread_t *) thread;

  priority = tp->sched_priority;

  if ((parms = (ThreadParms *) malloc (sizeof (*parms))) == NULL)
    {
      goto FAIL0;
    }

  parms->tid = thread;
  parms->start = start;
  parms->arg = arg;

  if (a != NULL)
    {
      stackSize = a->stacksize;
      tp->detachState = a->detachstate;
      priority = a->param.sched_priority;

      if ( (priority > pte_osThreadGetMaxPriority()) ||
           (priority < pte_osThreadGetMinPriority()) )
        {
          result = EINVAL;
          goto FAIL0;
        }

      /* Everything else */

      /*
       * Thread priority must be set to a valid system level
       * without altering the value set by pthread_attr_setschedparam().
       */

      if (PTHREAD_INHERIT_SCHED == a->inheritsched)
        {
          /*
           * If the thread that called pthread_create() is an OS thread
           * then the inherited priority could be the result of a temporary
           * system adjustment. This is not the case for POSIX threads.
           */
          self = pthread_self ();
          priority = ((pte_thread_t *) self)->sched_priority;
        }


    }
  else
    {
      /*
       * Default stackSize
       */
      stackSize = PTHREAD_STACK_MIN;

    }

  tp->state = run ? PThreadStateInitial : PThreadStateSuspended;

  tp->keys = NULL;

  /*
   * Threads must be started in suspended mode and resumed if necessary
   * after _beginthreadex returns us the handle. Otherwise we set up a
   * race condition between the creating and the created threads.
   * Note that we also retain a local copy of the handle for use
   * by us in case thread.p->threadH gets NULLed later but before we've
   * finished with it here.
   */
  result = pthread_mutex_lock (&tp->threadLock);

  if (0 == result)
    {
      /*
       * Must record the thread's sched_priority as given,
       * not as finally adjusted.
       */
      tp->sched_priority = priority;

      (void) pthread_mutex_unlock (&tp->threadLock);
    }

  osResult = pte_osThreadCreate(pte_threadStart,
                                stackSize,
                                priority,
                                parms,
                                &(tp->threadId));

  if (osResult == PTE_OS_OK)
    {
      pte_osThreadStart(tp->threadId);
      result = 0;
    }
  else
    {
      tp->threadId = 0;
      result = EAGAIN;
      goto FAIL0;
    }

  /*
   * Fall Through Intentionally
   */

  /*
   * ------------
   * Failure Code
   * ------------
   */

FAIL0:
  if (result != 0)
    {

      pte_threadDestroy (thread);
      tp = NULL;

      if (parms != NULL)
        {
          free (parms);
        }
    }
  else
    {
      if (tid != NULL)
        {
          *tid = thread;
        }
    }

  return (result);

}				/* pthread_create */