[Syrinx]

void OnAccept(const SOCKET DataSocket)
{
 LPFTPDSession FTPDSessionInfo = NULL;
 EnterCriticalSection(&LinkListSession);
 FTPDSessionInfo = GetInfo(DataSocket);
 LeaveCriticalSection(&LinkListSession);

 if (FTPDSessionInfo == NULL)
 {
	 return ;
 }
 SendReadyInfo(FTPDSessionInfo);
}

void OnWrite(const SOCKET DataSocket)
{
 LPFTPDSession FTPDSessionInfo = NULL;
 EnterCriticalSection(&LinkListSession);
 FTPDSessionInfo = GetInfo(DataSocket);
 LeaveCriticalSection(&LinkListSession);

 if (FTPDSessionInfo == NULL)
 {
	 return ;
 }

 switch(FTPDSessionInfo->TransferAction)
 {
     case DOWNLOADFILE:
		 printf("Send File\n");
		 SendFileContent(DataSocket,FTPDSessionInfo);
		 break;
	 case UPLOADFILE:
		 break;
     case LISTFILE:
         printf("Send List\n");
		 SendListContent(FTPDSessionInfo);
     default:
		 break;
 }
}


LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
 if (uMsg == WM_LISTENSOCKET)
 {
	 switch(WSAGETSELECTEVENT(lParam))
	 {
		 case FD_ACCEPT:
			 if (!WSAGETSELECTERROR(lParam))
			 {
				 HandleIncomingConnection(wParam,hwnd);
			 }
			 break;
         case FD_CLOSE:
             break;
	 }
	 return 0;
 }

 if (uMsg == WM_CONTROLSOCKET)
 {
	 switch(WSAGETSELECTEVENT(lParam))
	 {
		 case FD_READ:
			 HandleCommand(wParam);
			 break;
         case FD_WRITE:
			 break;
         case FD_CLOSE:
			  FreeClientSession(wParam);
	          DecrementClientCount();
			  printf("ControlSocket %d Disconnected\n",wParam);
              break;
	 }
	 return 0;
 }

 if (uMsg == WM_DATASOCKET)
 {
	 switch(WSAGETSELECTEVENT(lParam))
	 {
		 case FD_ACCEPT:
			 printf("DataSocket %d Accepted\n",wParam);
			 OnAccept((SOCKET)wParam);
			 break;
         case FD_CONNECT:
			 printf("Data Socket %d Connected\n",wParam);
			 break;
		 case FD_READ:
			 break;
         case FD_WRITE:
			 printf("Data Socket %d Is Writable\n",wParam);
			 OnWrite((SOCKET)wParam);
			 printf("OnWrite Complete\n");
			 break;
         case FD_CLOSE:
			 printf("DataSocket %d Disconnected\n",wParam);
             break;
	 }
	 return 0;
 }
 return DefWindowProc(hwnd, uMsg, wParam, lParam);
}

BOOL SendFileContent(const SOCKET DataSocket,LPFTPDSession FTPDSessionInfo)
{
 if (FTPDSessionInfo->FileHandle == INVALID_HANDLE_VALUE || FTPDSessionInfo->FileBuffer == NULL)
 {
	 return FALSE;
 }
 BOOL Flag = FALSE;
 DWORD ByteToRead = 0;

 if (FTPDSessionInfo->TransferBytes > 0)
 {
     if (myFileSeek(FTPDSessionInfo->FileHandle, FTPDSessionInfo->TransferBytes,FILE_BEGIN) == INVALID_SET_FILE_POINTER)
	 {
	       return FALSE;
	 }
	 printf("Reset %d\n",FTPDSessionInfo->TransferBytes);
 }

 while(TRUE)
 {
	 if (FTPDSessionInfo->PostedBytes == READYSEND)
	 {
	   if (!ReadFile(FTPDSessionInfo->FileHandle,FTPDSessionInfo->FileBuffer,1024,&ByteToRead,NULL))
 	   {
		   printf("POut Here\n");
		   break;
	   }
	   
 	   if (ByteToRead == 0)
	   {
		   printf("Out Here %d\n",GetLastError());
	 	   break;
	   }
	 }

	 int nByteSent = send(DataSocket,FTPDSessionInfo->FileBuffer,ByteToRead,0);
	 if (nByteSent == SOCKET_ERROR)
	 {
		 if (WSAGetLastError() != WSAEWOULDBLOCK)
         {
			 printf("Error\n");
			 break;
		 }
		 nByteSent = 0;
	 }

	 FTPDSessionInfo->TransferBytes += nByteSent;
	 if (FTPDSessionInfo->FileSize > 0)
	 {
		 FTPDSessionInfo->Completion = (float)FTPDSessionInfo->TransferBytes / FTPDSessionInfo->FileSize * 100;
	 }

	 if (nByteSent < (int)ByteToRead)
	 {
		 printf("Buffer Full\n");
		 return FALSE;
	 }
	 printf("%d:Post %d Bytes\n",DataSocket,FTPDSessionInfo->TransferBytes);
 }
 CleanUP Stuff
}

I try to code a ftpd with asynchronous functions,but I found a problem.whenevev the ftpd sends about 400K data thru data socket,the buffer is full,so I return(see the code SendFileContent()),but for my surprise,the ftpd won't generate a new FD_WRITE event for that data socket again even there is room for the buffer.
Can you take a glance and tell me what's wrong?

thanks a lot