POSIX Threads for Windows Code

/*
 * tryentercs.c
 *
 *
 * --------------------------------------------------------------------------
 *
 *      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.
 *
 * --------------------------------------------------------------------------
 *
 * See if we have the TryEnterCriticalSection function.
 * Does not use any part of pthreads.
 */

#include <windows.h>
#include <process.h>
#include <stdio.h>

/*
 * Function pointer to TryEnterCriticalSection if it exists
 * - otherwise NULL
 */
BOOL (WINAPI *_try_enter_critical_section)(LPCRITICAL_SECTION) =
NULL;

/*
 * Handle to kernel32.dll
 */
static HINSTANCE _h_kernel32;


int
main()
{
  CRITICAL_SECTION cs;

  SetLastError(0);

  printf("Last Error [main enter] %ld\n", (long) GetLastError());

  /*
   * Load KERNEL32 and try to get address of TryEnterCriticalSection
   */
  _h_kernel32 = LoadLibrary(TEXT("KERNEL32.DLL"));
  _try_enter_critical_section =
        (BOOL (WINAPI *)(LPCRITICAL_SECTION))
        GetProcAddress(_h_kernel32,
                         (LPCSTR) "TryEnterCriticalSection");

  if (_try_enter_critical_section != NULL)
    {
      InitializeCriticalSection(&cs);

      SetLastError(0);

      if ((*_try_enter_critical_section)(&cs) != 0)
        {
          LeaveCriticalSection(&cs);
        }
	else
	  {
	    printf("Last Error [try enter] %ld\n", (long) GetLastError());

	    _try_enter_critical_section = NULL;
	  }
      DeleteCriticalSection(&cs);
    }

  (void) FreeLibrary(_h_kernel32);

  printf("This system %s TryEnterCriticalSection.\n",
         (_try_enter_critical_section == NULL) ? "DOES NOT SUPPORT" : "SUPPORTS");
  printf("POSIX Mutexes will be based on Win32 %s.\n",
         (_try_enter_critical_section == NULL) ? "Mutexes" : "Critical Sections");

  return(0);
}