sem_timedwait.c

很有名的一款用于组织DDoS的恶意机器人程序。仅供研究学习

/*
 * -------------------------------------------------------------
 *
 * Module: sem_timedwait.c
 *
 * Purpose:
 *	Semaphores aren't actually part of the PThreads standard.
 *	They are defined by the POSIX Standard:
 *
 *		POSIX 1003.1b-1993	(POSIX.1b)
 *
 * -------------------------------------------------------------
 *
 * --------------------------------------------------------------------------
 *
 *      Pthreads-win32 - POSIX Threads Library for Win32
 *      Copyright(C) 1998 John E. Bossom
 *      Copyright(C) 1999,2003 Pthreads-win32 contributors
 * 
 *      Contact Email: [e-mail]
 * 
 *      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
 */

#ifndef _UWIN
#include <process.h>
#endif
#ifndef NEED_FTIME
#include <sys/timeb.h>
#endif

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


int
sem_timedwait (sem_t * sem, const struct timespec * abstime)
     /*
      * ------------------------------------------------------
      * DOCPUBLIC
      *      This function waits on a semaphore possibly until
      *      'abstime' time.
      *
      * PARAMETERS
      *      sem
      * 	     pointer to an instance of sem_t
      *
      *      abstime
      * 	     pointer to an instance of struct timespec
      *
      * DESCRIPTION
      *      This function waits on a semaphore. If the
      *      semaphore value is greater than zero, it decreases
      *      its value by one. If the semaphore value is zero, then
      *      the calling thread (or process) is blocked until it can
      *      successfully decrease the value or until interrupted by
      *      a signal.
      *
      *      If 'abstime' is a NULL pointer then this function will
      *      block until it can successfully decrease the value or
      *      until interrupted by a signal.
      *
      * RESULTS
      * 	     0		     successfully decreased semaphore,
      * 	     -1 	     failed, error in errno
      * ERRNO
      * 	     EINVAL	     'sem' is not a valid semaphore,
      * 	     ENOSYS	     semaphores are not supported,
      * 	     EINTR	     the function was interrupted by a signal,
      * 	     EDEADLK	     a deadlock condition was detected.
      * 	     ETIMEDOUT	     abstime elapsed before success.
      *
      * ------------------------------------------------------
      */
{
  int result = 0;

#ifdef NEED_FTIME

  struct timespec currSysTime;

#else /* NEED_FTIME */

  struct _timeb currSysTime;

#endif /* NEED_FTIME */

  const DWORD NANOSEC_PER_MILLISEC = 1000000;
  const DWORD MILLISEC_PER_SEC = 1000;
  DWORD milliseconds;

  if (sem == NULL)
    {
      result = EINVAL;
    }
  else
    {
      if (abstime == NULL)
				{
					milliseconds = INFINITE;
				}
      else
				{
					milliseconds = 0;

					/* 
					 * Calculate timeout as milliseconds from current system time. 
					 */
					
					/* get current system time */
					
#ifdef NEED_FTIME

					{
						FILETIME ft;
						SYSTEMTIME st;

						GetSystemTime(&st);
						SystemTimeToFileTime(&st, &ft);
						/*
						 * GetSystemTimeAsFileTime(&ft); would be faster,
						 * but it does not exist on WinCE
						 */

						ptw32_filetime_to_timespec(&ft, &currSysTime);
					}

					/*
					 * subtract current system time from abstime in a way that checks
					 * that abstime is never in the past, or is never equivalent to the
					 * defined INFINITE value (0xFFFFFFFF).
					 */
					if (abstime->tv_sec >= currSysTime.tv_sec)
						{
							DWORD tmpMilliseconds;
							DWORD tmpCurrMilliseconds;

							tmpMilliseconds = (abstime->tv_sec - currSysTime.tv_sec) * MILLISEC_PER_SEC;
							tmpMilliseconds += ((abstime->tv_nsec + (NANOSEC_PER_MILLISEC/2))
								/ NANOSEC_PER_MILLISEC);
							tmpCurrMilliseconds = ((currSysTime.tv_nsec + (NANOSEC_PER_MILLISEC/2))
								/ NANOSEC_PER_MILLISEC);
							if (tmpMilliseconds > tmpCurrMilliseconds)
								{
									milliseconds = tmpMilliseconds - tmpCurrMilliseconds;
									if (milliseconds == INFINITE)
										{
											milliseconds--;
										}
								}
						}

#else /* NEED_FTIME */
					_ftime(&currSysTime);

					/*
					 * subtract current system time from abstime in a way that checks
					 * that abstime is never in the past, or is never equivalent to the
					 * defined INFINITE value (0xFFFFFFFF).
					 */
					if (abstime->tv_sec >= currSysTime.time)
						{
							DWORD tmpMilliseconds;

							tmpMilliseconds = (abstime->tv_sec - currSysTime.time) * MILLISEC_PER_SEC;
							tmpMilliseconds += ((abstime->tv_nsec + (NANOSEC_PER_MILLISEC/2))
								/ NANOSEC_PER_MILLISEC);
							if (tmpMilliseconds > (DWORD) currSysTime.millitm)
								{
									milliseconds = tmpMilliseconds - currSysTime.millitm;
									if (milliseconds == INFINITE)
										{
											milliseconds--;
										}
								}
						}

#endif /* NEED_FTIME */

				}

#ifdef NEED_SEM
			
      result = (pthreadCancelableTimedWait ((*sem)->event, milliseconds));
			
#else /* NEED_SEM */
			
      result = (pthreadCancelableTimedWait ((*sem)->sem, milliseconds));

#endif

    }

  if (result != 0)
    {

      errno = result;
      return -1;

    }

#ifdef NEED_SEM

  ptw32_decrease_semaphore(sem);

#endif /* NEED_SEM */

  return 0;

}				/* sem_timedwait */