unsafe private SerialStreamAsyncResult BeginWriteCore(byte[] array, int offset, int numBytes, AsyncCallback userCallback, Object stateObject)
{
// Create and store async stream class library specific data in the
// async result
SerialStreamAsyncResult asyncResult = new SerialStreamAsyncResult();
asyncResult._userCallback = userCallback;
asyncResult._userStateObject = stateObject;
asyncResult._isWrite = true;
// For Synchronous IO, I could go with either a callback and using
// the managed Monitor class, or I could create a handle and wait on it.
ManualResetEvent waitHandle = new ManualResetEvent(false);
asyncResult._waitHandle = waitHandle;
// Create a managed overlapped class
// We will set the file offsets later
Overlapped overlapped = new Overlapped(0, 0, IntPtr.Zero, asyncResult);
// Pack the Overlapped class, and store it in the async result
NativeOverlapped* intOverlapped = overlapped.Pack(IOCallback, array);
asyncResult._overlapped = intOverlapped;
int hr = 0;
// queue an async WriteFile operation and pass in a packed overlapped
int r = WriteFileNative(array, offset, numBytes, intOverlapped, out hr);
// WriteFile, the OS version, will return 0 on failure. But
// my WriteFileNative wrapper returns -1. My wrapper will return
// the following:
// On error, r==-1.
// On async requests that are still pending, r==-1 w/ hr==ERROR_IO_PENDING
// On async requests that completed sequentially, r==0
// Note that you will NEVER RELIABLY be able to get the number of bytes
// written back from this call when using overlapped IO! You must
// not pass in a non-null lpNumBytesWritten to WriteFile when using
// overlapped structures!
if (r==-1)
{
if (hr != NativeMethods.ERROR_IO_PENDING)
{
if (hr == NativeMethods.ERROR_HANDLE_EOF)
InternalResources.EndOfFile();
else
InternalResources.WinIOError(hr, String.Empty);
}
}
return asyncResult;
}
internal unsafe void WaitForCommEvent()
{
int unused = 0;
bool doCleanup = false;
NativeOverlapped* intOverlapped = null;
while (!ShutdownLoop) {
SerialStreamAsyncResult asyncResult = null;
if (isAsync) {
asyncResult = new SerialStreamAsyncResult();
asyncResult._userCallback = null;
asyncResult._userStateObject = null;
asyncResult._isWrite = false;
// we're going to use _numBytes for something different in this loop. In this case, both
// freeNativeOverlappedCallback and this thread will decrement that value. Whichever one decrements it
// to zero will be the one to free the native overlapped. This guarantees the overlapped gets freed
// after both the callback and GetOverlappedResult have had a chance to use it.
asyncResult._numBytes = 2;
asyncResult._waitHandle = waitCommEventWaitHandle;
waitCommEventWaitHandle.Reset();
Overlapped overlapped = new Overlapped(0, 0, waitCommEventWaitHandle.SafeWaitHandle.DangerousGetHandle(), asyncResult);
// Pack the Overlapped class, and store it in the async result
intOverlapped = overlapped.Pack(freeNativeOverlappedCallback, null);
}
fixed (int* eventsOccurredPtr = &eventsOccurred) {
if (UnsafeNativeMethods.WaitCommEvent(handle, eventsOccurredPtr, intOverlapped) == false)
{
int hr = Marshal.GetLastWin32Error();
// When a device is disconnected unexpectedly from a serial port, there appear to be
// at least two error codes Windows or drivers may return.
if (hr == NativeMethods.ERROR_ACCESS_DENIED || hr == NativeMethods.ERROR_BAD_COMMAND) {
doCleanup = true;
break;
}
if (hr == NativeMethods.ERROR_IO_PENDING)
{
Debug.Assert(isAsync, "The port is not open for async, so we should not get ERROR_IO_PENDING from WaitCommEvent");
int error;
// if we get IO pending, MSDN says we should wait on the WaitHandle, then call GetOverlappedResult
// to get the results of WaitCommEvent.
bool success = waitCommEventWaitHandle.WaitOne();
Debug.Assert(success, "waitCommEventWaitHandle.WaitOne() returned error " + Marshal.GetLastWin32Error());
do {
// NOTE: GetOverlappedResult will modify the original pointer passed into WaitCommEvent.
success = UnsafeNativeMethods.GetOverlappedResult(handle, intOverlapped, ref unused, false);
error = Marshal.GetLastWin32Error();
}
while (error == NativeMethods.ERROR_IO_INCOMPLETE && !ShutdownLoop && !success);
if (!success) {
// Ignore ERROR_IO_INCOMPLETE and ERROR_INVALID_PARAMETER, because there's a chance we'll get
// one of those while shutting down
if (! ( (error == NativeMethods.ERROR_IO_INCOMPLETE || error == NativeMethods.ERROR_INVALID_PARAMETER) && ShutdownLoop))
Debug.Assert(false, "GetOverlappedResult returned error, we might leak intOverlapped memory" + error.ToString(CultureInfo.InvariantCulture));
}
}
else if (hr != NativeMethods.ERROR_INVALID_PARAMETER) {
// ignore ERROR_INVALID_PARAMETER errors. WaitCommError seems to return this
// when SetCommMask is changed while it's blocking (like we do in Dispose())
Debug.Assert(false, "WaitCommEvent returned error " + hr);
}
}
}
if (!ShutdownLoop)
CallEvents(eventsOccurred);
if (isAsync) {
if (Interlocked.Decrement(ref asyncResult._numBytes) == 0)
Overlapped.Free(intOverlapped);
}
} // while (!ShutdownLoop)
if (doCleanup) {
// the rest will be handled in Dispose()
endEventLoop = true;
Overlapped.Free(intOverlapped);
}
eventLoopEndedSignal.Set();
}
private unsafe SerialStreamAsyncResult BeginWriteCore(byte[] array, int offset, int numBytes, AsyncCallback userCallback, object stateObject)
{
SerialStreamAsyncResult ar = new SerialStreamAsyncResult {
_userCallback = userCallback,
_userStateObject = stateObject,
_isWrite = true
};
ManualResetEvent event2 = new ManualResetEvent(false);
ar._waitHandle = event2;
NativeOverlapped* overlapped = new Overlapped(0, 0, IntPtr.Zero, ar).Pack(IOCallback, array);
ar._overlapped = overlapped;
int hr = 0;
if ((this.WriteFileNative(array, offset, numBytes, overlapped, out hr) == -1) && (hr != 0x3e5))
{
if (hr == 0x26)
{
InternalResources.EndOfFile();
return ar;
}
InternalResources.WinIOError(hr, string.Empty);
}
return ar;
}
