Fix timeout calculations.

1 files changed, 59 insertions, 75 deletions

diff --git a/sem_timedwait.c b/sem_timedwait.c
index d78e10f..a600ff4 100644
--- a/sem_timedwait.c
+++ b/sem_timedwait.c
@@ -108,6 +108,8 @@ sem_timedwait (sem_t * sem, const struct timespec * abstime)
   const DWORD NANOSEC_PER_MILLISEC = 1000000;
   const DWORD MILLISEC_PER_SEC = 1000;
   DWORD milliseconds;
+  DWORD tmpAbsMilliseconds;
+  DWORD tmpCurrMilliseconds;
 
   if (sem == NULL)
     {
@@ -116,88 +118,70 @@ sem_timedwait (sem_t * sem, const struct timespec * abstime)
   else
     {
       if (abstime == NULL)
-				{
-					milliseconds = INFINITE;
-				}
+	{
+	  milliseconds = INFINITE;
+	}
       else
-				{
-					milliseconds = 0;
-
-					/* 
-					 * Calculate timeout as milliseconds from current system time. 
-					 */
-					
-					/* get current system time */
-					
+	{
+	  /* 
+	   * Calculate timeout as milliseconds from current system time. 
+	   */
+
+	  /*
+	   * 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).
+	   *
+	   * Assume all integers are unsigned, i.e. cannot test if less than 0.
+	   */
+	  tmpAbsMilliseconds =  abstime->tv_sec * MILLISEC_PER_SEC;
+	  tmpAbsMilliseconds += (abstime->tv_nsec + (NANOSEC_PER_MILLISEC/2)) / NANOSEC_PER_MILLISEC;
+
+	  /* 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--;
-										}
-								}
-						}
+	  {
+	    FILETIME ft;
+	    SYSTEMTIME st;
 
-#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--;
-										}
-								}
-						}
+	    GetSystemTime(&st);
+	    SystemTimeToFileTime(&st, &ft);
+	    /*
+	     * GetSystemTimeAsFileTime(&ft); would be faster,
+	     * but it does not exist on WinCE
+	     */
+
+	    ptw32_filetime_to_timespec(&ft, &currSysTime);
+	  }
+
+	  tmpCurrMilliseconds = currSysTime.tv_sec * MILLISEC_PER_SEC;
+	  tmpCurrMilliseconds += (currSysTime.tv_nsec + (NANOSEC_PER_MILLISEC/2)) / NANOSEC_PER_MILLISEC;
+
+#else /* ! NEED_FTIME */
+
+	  _ftime(&currSysTime);
+
+	  tmpCurrMilliseconds = (DWORD) currSysTime.time * MILLISEC_PER_SEC;
+	  tmpCurrMilliseconds += (DWORD) currSysTime.millitm;
 
 #endif /* NEED_FTIME */
 
-				}
+	  if (tmpAbsMilliseconds > tmpCurrMilliseconds)
+	    {
+	      milliseconds = tmpAbsMilliseconds - tmpCurrMilliseconds;
+	      if (milliseconds == INFINITE)
+		{
+		  /* Timeouts must be finite */
+		  milliseconds--;
+		}
+	    }
+	  else
+	    {
+	      /* The abstime given is in the past */
+	      milliseconds = 0;
+	    }
+	}
 
 #ifdef NEED_SEM