Getting filehandle from serialport class

Im using the serialPort class in visual C# do do some communication. But i also need to do some low level stuff. I assume the SerialPort class creates a filehandle like FileHandle = CreateFile(ComPort,.... Is there any way to get this handle??? I'm hoping to not have to write a complete new SerialPort class :)

If you look at the SerialPort class using a disassembler such as Reflector then, when you call the Open() method, an instance of an internal class called SerialStream is created and assigned to the SerialPort's private field, internalSerialStream.

The SerialStream, in turn, creates a file and stores a SafeFileHandle to it in its internal _handle field. The SafeFileHandle wraps the native handle (of type IntPtr) in its protected handle field.

It should be possible to get at this handle using reflection. The following code compiles OK and should work though I haven't been able to test it as the laptop I'm using right now doesn't have a serial port:

using System;

using System.IO.Ports;

using System.Reflection;

using Microsoft.Win32.SafeHandles;

class Program

{

static void Main()

{

SerialPort sp = new SerialPort(); // use default settings

sp.Open();

Type t = typeof(SerialPort);

BindingFlags bf = BindingFlags.Instance | BindingFlags.NonPublic;

FieldInfo fi = t.GetField("internalSerialStream", bf);

object ss = fi.GetValue(sp);

Type t2 = fi.FieldType;

FieldInfo fi2 = t2.GetField("_handle", bf);

SafeFileHandle _handle = (SafeFileHandle)fi2.GetValue(ss);

Type t3 = typeof(SafeFileHandle);

FieldInfo fi3 = t3.GetField("handle", bf);

IntPtr handle = (IntPtr)fi3.GetValue(_handle);

sp.Close();

Console.WriteLine(handle);

Console.ReadKey();

}

2 Replies

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Vulpes15y ago
Accepted answer
If you look at the SerialPort class using a disassembler such as Reflector then, when you call the Open() method, an instance of an internal class called SerialStream is created and assigned to the SerialPort's private field, internalSerialStream.

The SerialStream, in turn, creates a file and stores a SafeFileHandle to it in its internal _handle field. The SafeFileHandle wraps the native handle (of type IntPtr) in its protected handle field.

It should be possible to get at this handle using reflection. The following code compiles OK and should work though I haven't been able to test it as the laptop I'm using right now doesn't have a serial port:

using System;
using System.IO.Ports;
using System.Reflection;
using Microsoft.Win32.SafeHandles;

class Program
{
static void Main()
{
SerialPort sp = new SerialPort(); // use default settings
sp.Open();
Type t = typeof(SerialPort);
BindingFlags bf = BindingFlags.Instance | BindingFlags.NonPublic;
FieldInfo fi = t.GetField("internalSerialStream", bf);
object ss = fi.GetValue(sp);
Type t2 = fi.FieldType;
FieldInfo fi2 = t2.GetField("_handle", bf);
SafeFileHandle _handle = (SafeFileHandle)fi2.GetValue(ss);
Type t3 = typeof(SafeFileHandle);
FieldInfo fi3 = t3.GetField("handle", bf);
IntPtr handle = (IntPtr)fi3.GetValue(_handle);
sp.Close();
Console.WriteLine(handle);
Console.ReadKey();
}
}
Geir Ludde15y ago
Thanks works fine :)