errno.c

/*
 * errno.c
 *
 * Description:
 * This translation unit implements routines associated with spawning a new
 * thread.
 *
 * --------------------------------------------------------------------------
 *
 *      Pthreads4w - POSIX Threads for Windows
 *      Copyright 1998 John E. Bossom
 *      Copyright 1999-2018, Pthreads4w contributors
 *
 *      Homepage: https://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:
 *
 *      https://sourceforge.net/p/pthreads4w/wiki/Contributors/
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#if defined(NEED_ERRNO)

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

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