private static IEnumerator <IAsyncResult> AsyncStreamCopyImpl(CrcStream source, CrcStream destination, long numBytes, int bufferSize, AsyncCrcStreamCopy.ComputeAndLogCrcMethod computeCrcMethodForCrcLogging, TimeSpan timeout, AsyncIteratorContext <long> context)
{
Exception exception;
BufferWrapper buffer = null;
BufferWrapper bufferWrapper = null;
try
{
Duration startingNow = Duration.StartingNow;
IAsyncResult asyncResult = null;
IAsyncResult asyncResult1 = null;
buffer = BufferPool.GetBuffer(bufferSize);
bufferWrapper = BufferPool.GetBuffer(bufferSize);
long num = (long)0;
long?nullable = null;
context.ResultData = (long)0;
bool canTimeout = source.CanTimeout;
bool flag = destination.CanTimeout;
while (true)
{
int timeoutInMS = AsyncCrcStreamCopy.TimeSpanToTimeoutInMS(startingNow.Remaining(timeout));
if (timeoutInMS == 0)
{
throw new TimeoutException("The asynchronous stream copy timed out.");
}
if (canTimeout)
{
try
{
source.ReadTimeout = timeoutInMS;
}
catch (InvalidOperationException invalidOperationException)
{
canTimeout = false;
}
}
if (flag)
{
try
{
destination.WriteTimeout = timeoutInMS;
}
catch (InvalidOperationException invalidOperationException1)
{
flag = false;
}
}
if (numBytes > (long)0)
{
asyncResult = source.BeginRead(buffer.Buffer, 0, (int)Math.Min((long)((int)buffer.Buffer.Length), numBytes), context.GetResumeCallback(), context.GetResumeState("AsyncCrcStreamCopy.source.Read"));
}
exception = null;
if (num > (long)0)
{
try
{
asyncResult1 = destination.BeginWrite(bufferWrapper.Buffer, 0, (int)num, nullable, context.GetResumeCallback(), context.GetResumeState("AsyncCrcStreamCopy.dest.Write"));
}
catch (Exception exception1)
{
exception = exception1;
}
if (exception == null)
{
yield return(asyncResult1);
try
{
destination.EndWrite(asyncResult1);
}
catch (Exception exception2)
{
exception = exception2;
}
}
}
if (numBytes <= (long)0)
{
num = (long)0;
}
else
{
yield return(asyncResult);
num = (long)source.EndRead(out nullable, asyncResult);
}
if (exception != null)
{
throw ExceptionCloner.AttemptClone(exception, RethrowableWrapperBehavior.NoWrap);
}
if (num < (long)0)
{
break;
}
numBytes -= num;
AsyncIteratorContext <long> resultData = context;
resultData.ResultData = resultData.ResultData + num;
if (computeCrcMethodForCrcLogging != null)
{
computeCrcMethodForCrcLogging(buffer.Buffer, 0, (int)num, context.ResultData);
}
AsyncCrcStreamCopy.Swap <BufferWrapper>(ref buffer, ref bufferWrapper);
if (num <= (long)0)
{
goto Label2;
}
}
throw new TimeoutException("Reading from the stream resulted in a negative number of bytes read. This typically means an HttpWebRequest was aborted.");
}
finally
{
if (buffer != null)
{
BufferPool.ReleaseBuffer(buffer);
}
if (bufferWrapper != null)
{
BufferPool.ReleaseBuffer(bufferWrapper);
}
}
Label2:
yield break;
throw new TimeoutException("The asynchronous stream copy timed out.");
throw ExceptionCloner.AttemptClone(exception, RethrowableWrapperBehavior.NoWrap);
}