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ntquerysysteminformation (ntdll)
Retrieves the specified system information. Specify the information you want, a pointer to hold the results.

C# Signature:

/// <summary>Retrieves the specified system information.</summary>
/// <param name="InfoClass">indicate the kind of system information to be retrieved</param>
/// <param name="Info">a buffer that receives the requested information</param>
/// <param name="Size">The allocation size of the buffer pointed to by Info</param>
/// <param name="Length">If null, ignored.  Otherwise tells you the size of the information returned by the kernel.</param>
/// <returns>Status Information</returns>
public static extern NtStatus NtQuerySystemInformation(SYSTEM_INFORMATION_CLASS InfoClass, IntPtr Info, uint Size, out uint Length);

VB Signature:

Declare Function NtQuerySystemInformation Lib "ntdll.dll" (TODO) As TODO

User-Defined Types:




Tips & Tricks:

Please add some!

Sample Code:

//helper method with "dynamic" buffer allocation
public static IntPtr NtQuerySystemInformation(SYSTEM_INFORMATION_CLASS infoClass, uint infoLength = 0)
    if (infoLength == 0)
        infoLength = 0x10000;

    var infoPtr = Marshal.AllocHGlobal((int)infoLength);

    var tries = 0;
    while (true)
        var result = NtQuerySystemInformation(infoClass, infoPtr, infoLength, out infoLength);

        if (result == NtStatus.Success)
             return infoPtr;

        Marshal.FreeHGlobal(infoPtr);  //free pointer when not Successful

        if (result != NtStatus.InfoLengthMismatch && result != NtStatus.BufferOverflow && result != NtStatus.BufferTooSmall)
            //throw new Exception("Unhandled NtStatus " + result);
            return IntPtr.Zero;

        if (++tries > 5)
            return IntPtr.Zero;

        infoPtr = Marshal.AllocHGlobal((int)infoLength);

public void Test()
        result = 0;



        arr = new Int32[] { (Int32)Commands.MEMORYLIST };

        buff = Marshal.AllocHGlobal(1024); // should be more than adequate
        result = (UInt32)NativeMethods.NtQuerySystemInformation(NativeMethods.SYSTEM_INFORMATION_CLASS.SystemMemoryListInformation, buff, result, out returnSize);
        if (result != 0)
            // Most likely error is InfoLengthMismatch = 0xc0000004 -- meaning you need to make the buffer larger
            throw new System.ComponentModel.Win32Exception(((NativeMethods.NtStatus)result).ToString());
        if (NativeMethods.SYSTEM_MEMORY_LIST_INFORMATION_SIZE == 0)
            NativeMethods.SYSTEM_MEMORY_LIST_INFORMATION_SIZE = returnSize;
        MemoryList = (NativeMethods.SYSTEM_MEMORY_LIST_INFORMATION)Marshal.PtrToStructure(buff, typeof(NativeMethods.SYSTEM_MEMORY_LIST_INFORMATION));


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