errno.c

/*
 * errno.c
 *
 * Description:
 * This translation unit implements routines associated with spawning a new
 * thread.
 *
 * --------------------------------------------------------------------------
 *
 *      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"

#if defined(NEED_ERRNO)

static int reallyBad = ENOMEM;

/*
 * Re-entrant errno.
 *
 * Each thread has it's own errno variable in pthread_t.
 *
 * The benefit of using the pthread_t structure
 * instead of another TSD key is TSD keys are limited
 * on Win32 to 64 per process. Secondly, to implement
 * it properly without using pthread_t you'd need
 * to dynamically allocate an int on starting the thread
 * and store it manually into TLS and then ensure that you free
 * it on thread termination. We get all that for free
 * by simply storing the errno on the pthread_t structure.
 *
 * MSVC and Mingw32 already have their own thread-safe errno.
 *
 * #if defined( _REENTRANT ) || defined( _MT )
 * #define errno *_errno()
 *
 * int *_errno( void );
 * #else
 * extern int errno;
 * #endif
 *
 */

int *
_errno (void)
{
  pthread_t self;
  int *result;

  if ((self = pthread_self ()).p == NULL)
    {
      /*
       * Yikes! unable to allocate a thread!
       * Throw an exception? return an error?
       */
      result = &reallyBad;
    }
  else
    {
      result = (int *)(&((ptw32_thread_t *)self.p)->exitStatus);
    }

  return (result);

}				/* _errno */

#endif /* (NEED_ERRNO) */

#if ! defined(PTW32_BUILD_INLINED)
/*
 * Avoid "translation unit is empty" warnings
 */
typedef int foo;
#endif