pthread_key_create.c

/*
 * pthread_key_create.c
 *
 * Description:
 * POSIX thread functions which implement thread-specific data (TSD).
 *
 * --------------------------------------------------------------------------
 *
 *      pthreads-win32 - POSIX Threads Library for Win32
 *      Copyright(C) 1998 John E. Bossom
 *      Copyright(C) 1999-2021 pthreads-win32 / pthreads4w contributors
 *
 *      Homepage1: http://sourceware.org/pthreads-win32/
 *      Homepage2: http://sourceforge.net/projects/pthreads4w/
 *
 *      The current list of contributors is contained
 *      in the file CONTRIBUTORS 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
 *
 * --------------------------------------------------------------------------
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

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


/* TLS_OUT_OF_INDEXES not defined on WinCE */
#if !defined(TLS_OUT_OF_INDEXES)
#define TLS_OUT_OF_INDEXES 0xffffffff
#endif

int
pthread_key_create (pthread_key_t * key, void (PTW32_CDECL *destructor) (void *))
     /*
      * ------------------------------------------------------
      * DOCPUBLIC
      *      This function creates a thread-specific data key visible
      *      to all threads. All existing and new threads have a value
      *      NULL for key until set using pthread_setspecific. When any
      *      thread with a non-NULL value for key terminates, 'destructor'
      *      is called with key's current value for that thread.
      *
      * PARAMETERS
      *      key
      *              pointer to an instance of pthread_key_t
      *
      *
      * DESCRIPTION
      *      This function creates a thread-specific data key visible
      *      to all threads. All existing and new threads have a value
      *      NULL for key until set using pthread_setspecific. When any
      *      thread with a non-NULL value for key terminates, 'destructor'
      *      is called with key's current value for that thread.
      *
      * RESULTS
      *              0               successfully created semaphore,
      *              EAGAIN          insufficient resources or PTHREAD_KEYS_MAX
      *                              exceeded,
      *              ENOMEM          insufficient memory to create the key,
      *
      * ------------------------------------------------------
      */
{
  int result = 0;
  pthread_key_t newkey;

  if ((newkey = (pthread_key_t) calloc (1, sizeof (*newkey))) == NULL)
    {
      result = ENOMEM;
    }
  else if ((newkey->key = TlsAlloc ()) == TLS_OUT_OF_INDEXES)
    {
      result = EAGAIN;

      free (newkey);
      newkey = NULL;
    }
  else if (destructor != NULL)
    {
      /*
       * Have to manage associations between thread and key;
       * Therefore, need a lock that allows competing threads
       * to gain exclusive access to the key->threads list.
       *
       * The mutex will only be created when it is first locked.
       */
      newkey->keyLock = 0;
      newkey->destructor = destructor;
    }

  *key = newkey;

  return (result);
}