C# Signature:

[DllImport("ntdll.dll", SetLastError=true)]
static extern int NtQueryInformationProcess(IntPtr processHandle, int processInformationClass, IntPtr processInformation, uint processInformationLength, IntPtr returnLength);

or:

[DllImport("NTDLL.DLL", SetLastError=true)]
static extern int NtQueryInformationProcess(IntPtr hProcess, PROCESSINFOCLASS pic, ref PROCESS_BASIC_INFORMATION pbi, int cb, out int pSize);

or:

[DllImport("ntdll.dll", PreserveSig = false, SetLastError = true)]
public static extern void NtQueryInformationProcess(IntPtr ProcessHandle, PROCESSINFOCLASS ProcessInformationClass, out PROCESS_EXTENDED_BASIC_INFORMATION ProcessInformation, uint ProcessInformationLength, out uint ReturnLength);

VB Signature:

Declare Function NtQueryInformationProcess Lib "ntdll.dll" ( _
   processHandle As IntPtr, processInformationClass As Integer, _
   processInformation As IntPtr, processInformationLength As Integer, _
   returnLength As IntPtr) As Integer

User-Defined Types:

PROCESSINFOCLASS, PROCESS_BASIC_INFORMATION, PROCESS_EXTENDED_BASIC_INFORMATION

Notes:

See also OpenProcess, CloseHandle.

Tips & Tricks:

Please add some!

Sample Code:

    public static IntPtr GetPEBAddress()
    {
        //Get a handle to our own process
        IntPtr hProc = OpenProcess(0x001F0FFF, false, Process.GetCurrentProcess().Id);
        //Allocate memory for a new PROCESS_BASIC_INFORMATION structure
        IntPtr pbi = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(PROCESS_BASIC_INFORMATION)));
        //Allocate memory for a long
        IntPtr outLong = Marshal.AllocHGlobal(sizeof(long));
        IntPtr outPtr = IntPtr.Zero;

        int queryStatus = false;

        //Store API call success in a boolean
        queryStatus = NtQueryInformationProcess(hProc, 0, pbi, (uint)Marshal.SizeOf(typeof(PROCESS_BASIC_INFORMATION)), outLong);

        //Close handle and free allocated memory
        CloseHandle(hProc);
        Marshal.FreeHGlobal(outLong);

        //STATUS_SUCCESS = 0, so if API call was successful querySuccess should contain 0 ergo we reverse the check.
        if(!queryStatus )
        outPtr = PtrToStructure<PROCESS_BASIC_INFORMATION>(pbi, typeof(PROCESS_BASIC_INFORMATION)).PebBaseAddress;

        //Free allocated space
        Marshal.FreeHGlobal(pbi);

        //Return pointer to PEB base address
        return outPtr;
    }

Or:

    public static int GetParentProcessId()
    {
        PROCESS_BASIC_INFORMATION pbi = new PROCESS_BASIC_INFORMATION();

        //Get a handle to our own process
        IntPtr hProc = OpenProcess((ProcessAccessFlags)0x001F0FFF, false, Process.GetCurrentProcess().Id);

        try
        {
            int sizeInfoReturned;
            int queryStatus = NtQueryInformationProcess(hProc, (PROCESSINFOCLASS)0, ref pbi, pbi.Size, out sizeInfoReturned);
        }
        finally
        {
            if (!hProc.Equals(IntPtr.Zero))
            {
            //Close handle and free allocated memory
            CloseHandle(hProc);
            hProc = IntPtr.Zero;
            }
        }

        return (int)pbi.InheritedFromUniqueProcessId;
    }

Alternative Managed API:

Do you know one? Please contribute it!

Please edit this page!

Do you have...

• helpful tips or sample code to share for using this API in managed code?
• corrections to the existing content?
• variations of the signature you want to share?
• additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).