C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Common.Logging;
using System.IO;

namespace sample1
{
    public class Helper1
    {
        private static ILog log = LogManager.GetCurrentClassLogger();

        public Customer createCust(String CustId, String fileName)
        {

            Customer cst = new Customer();
            byte[] buffer = null;
            try
            {
                
                System.IO.FileStream fileStream = new System.IO.FileStream(fileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);

                System.IO.BinaryReader binaryReader = new System.IO.BinaryReader(fileStream);

                long totalBytes = new System.IO.FileInfo(fileName).Length;

                buffer = binaryReader.ReadBytes((Int32)totalBytes);

                DateTime attachmentId = DateTime.Now;
                cst.Id = attachmentId.ToString();
                cst.MimeType = getMimeType(fileName);
                cst.Value = buffer;
                fileStream.Close();
                binaryReader.Close();
            }
            catch (Exception e)
            {

                throw new Exception(e.Message);
            }

            return cust;
        }
}}

static void Main(string[] args)
{
    var portName = @"\\.\COM3";
    var handle = CreateFile(portName, 0, 0, IntPtr.Zero, 3, 0x80, IntPtr.Zero);
    if (handle == (IntPtr)(-1))
    {
        Console.WriteLine("Could not open " + portName + ": " 
            + new Win32Exception().Message);
        return;
    }
    var type = GetFileType(handle);
    Console.WriteLine("File " + portName + " reports its type as: " + type);
}

[DllImport("kernel32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall,
    SetLastError = true)]
public static extern IntPtr CreateFile(
    string lpFileName,
    uint dwDesiredAccess,
    uint dwShareMode,
    IntPtr SecurityAttributes,
    uint dwCreationDisposition,
    uint dwFlagsAndAttributes,
    IntPtr hTemplateFile);

[DllImport("kernel32.dll")]
static extern FileType GetFileType(IntPtr hFile);
enum FileType : uint
{
    UNKNOWN = 0x0000,
    DISK = 0x0001,
    CHAR = 0x0002,
    PIPE = 0x0003,
    REMOTE = 0x8000,
}