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Summary

The OpenProcess API

C# Signature:

[DllImport("kernel32.dll")]
static extern IntPtr OpenProcess(ProcessAccessFlags dwDesiredAccess, [MarshalAs(UnmanagedType.Bool)] bool bInheritHandle, int dwProcessId);

or

[DllImport("kernel32.dll")]
public static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, int dwProcessId);

VB.NET Signature:

<DllImport("kernel32.dll")> _
Private Shared Function OpenProcess(ByVal dwDesiredAccess As ProcessAccessFlags, <MarshalAs(UnmanagedType.Bool)> ByVal bInheritHandle As Boolean, ByVal dwProcessId As Integer) As IntPtr
End Function

Boo Signature:

[DllImport("kernel32")]
static def OpenProcess(dwDesiredAccess as ProcessAccess, bInheritHandle as bool, dwProcessId as int) as IntPtr:
     pass

User-Defined Types:

ProcessAccess

Notes:

See also CloseHandle,

Tips & Tricks:

Please add some!

Flags:

C#

[Flags]
enum ProcessAccessFlags : uint
{
    All = 0x001F0FFF,
    Terminate = 0x00000001,
    CreateThread = 0x00000002,
    VMOperation = 0x00000008,
    VMRead = 0x00000010,
    VMWrite = 0x00000020,
    DupHandle = 0x00000040,
    SetInformation = 0x00000200,
    QueryInformation = 0x00000400,
    Synchronize = 0x00100000
}

VB.NET

Enum ProcessAccessFlags As UInteger
    All = &H1F0FFF
    Terminate = &H1
    CreateThread = &H2
    VMOperation = &H8
    VMRead = &H10
    VMWrite = &H20
    DupHandle = &H40
    SetInformation = &H200
    QueryInformation = &H400
    Synchronize = &H100000
End Enum

Documentation

OpenProcess on MSDN

Sample Code (VB.NET):

' Get the handle of a running process
Dim curProcess As Process = Process.GetCurrentProcess()
hProcess = OpenProcess(PROCESS_ACCESS.PROCESS_QUERY_INFORMATION, True, curProcess.Id)
' Do something constructive
CloseHandle(hProcess)

C# Example

using System;

using System.Runtime.InteropServices;

using System.Text;

public class ShowProcessName

{

    [DllImport("Psapi.dll", SetLastError = true)]
    static extern bool EnumProcesses(
       [MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.U4)] [In][Out] UInt32[] processIds,
     UInt32 arraySizeBytes,
     [MarshalAs(UnmanagedType.U4)] out UInt32 bytesCopied
      );
    [Flags]
    enum ProcessAccessFlags : uint
    {
    All = 0x001F0FFF,
    Terminate = 0x00000001,
    CreateThread = 0x00000002,
    VMOperation = 0x00000008,
    VMRead = 0x00000010,
    VMWrite = 0x00000020,
    DupHandle = 0x00000040,
    SetInformation = 0x00000200,
    QueryInformation = 0x00000400,
    Synchronize = 0x00100000
    }

    [DllImport("psapi.dll")]
    static extern uint GetModuleBaseNameA(IntPtr hProcess, IntPtr hModule, StringBuilder lpBaseName, uint nSize);

    public ShowProcessName()
    {

    UInt32 arraySize = 120;
    UInt32 arrayBytesSize = arraySize * sizeof(UInt32);
    UInt32[] processIds = new UInt32[arraySize];
    UInt32 bytesCopied;

    EnumProcesses(processIds, arrayBytesSize, out bytesCopied);

    for (UInt32 index = 0; index < numIdsCopied; index++)
    {
        Console.WriteLine("ProcessIds[{0}] = {1}", index, processIds[index]);
        IntPtr Handle;
        Handle = OpenProcess(ProcessAccessFlags.QueryInformation | ProcessAccessFlags.VMRead, false, (int)processIds[index]);
        if ((int)Handle <= 4)
        continue;

        StringBuilder BaseName = new StringBuilder();

        GetModuleBaseNameA(Handle, (IntPtr)0, BaseName, 100);

    }

    }

}