Q:

Get Treeview(SysTreeView32) items text using win32 api

I am writing an application to automate some repetitive tasks at my job.
One of the task I wish to do, is to be able to automate the process of creating a recovery drive from "RecoveryDrive.exe" in windows 10. All the process is done, but at one step, a human need to select the drive in a SysTreeView32 control.
I have tried to find how to get the text of the current selected treeNodeItem.
I have the handle of the control, but when I try to read it, using a code sample found online, the recoveryDrive application crash. 
I'm suspecting this have to do with 64bits/32bits mismatch with the api methods I'm using and maybe ASCI and Unicode encoding mismatch ... I also think I need to use LocalAlloc inside of the target app Handle or memory
here is the pasteBin of the code in the present state.
It also have the 3 page I have based my code from. The app crash in the GetTreeItemText function when I'm using the sendMessage.
I have found some example on how to do this in C++, but I don't really understand it.
 public static string GetTreeItemText(IntPtr treeViewHwnd, IntPtr hItem)
            {
                int ret;
                TVITEM tvi = new TVITEM();
                IntPtr pszText = LocalAlloc(0x40, MY_MAXLVITEMTEXT);

                tvi.mask = TVIF_TEXT;
                tvi.hItem = hItem;
                tvi.cchTextMax = MY_MAXLVITEMTEXT;
                tvi.pszText = pszText;

                ret = SendMessageTVI(treeViewHwnd, TVM_GETITEM, 0, ref tvi);
                string buffer = Marshal.PtrToStringUni((IntPtr)tvi.pszText,
                MY_MAXLVITEMTEXT);

                //char[] arr = buffer.ToCharArray(); //<== use this array to look at the bytes in debug mode

                LocalFree(pszText);
                return buffer;
            }

A:

The LPARAM of the TVM_GETITEM message is a pointer to a TVITEM structure.  The thing is, that structure MUST be allocated in the same process that owns the TreeView control.  So, when sending TVM_GETITEM across process boundaries, you must use VirtualAllocEx() to allocate the TVITEM and its pszText buffer in the address space of the target process, and then use WriteProcessMemory()/ReadProcessMemory() to write/read that structure's data.
Try something like this (you can find declarations for the Win32 API functions used at PInvoke.net):
public static string GetTreeItemText(IntPtr treeViewHwnd, IntPtr hItem)
{
    string itemText;

    uint pid;
    GetWindowThreadProcessId(treeViewHwnd, out pid);

    IntPtr process = OpenProcess(ProcessAccessFlags.VirtualMemoryOperation | ProcessAccessFlags.VirtualMemoryRead | ProcessAccessFlags.VirtualMemoryWrite | ProcessAccessFlags.QueryInformation, false, pid);
    if (process == IntPtr.Zero)
        throw new Exception("Could not open handle to owning process of TreeView", new Win32Exception());

    try
    {
        uint tviSize = Marshal.SizeOf(typeof(TVITEM));

        uint textSize = MY_MAXLVITEMTEXT;
        bool isUnicode = IsWindowUnicode(treeViewHwnd);
        if (isUnicode)
            textSize *= 2;

        IntPtr tviPtr = VirtualAllocEx(process, IntPtr.Zero, tviSize + textSize, AllocationType.Commit, MemoryProtection.ReadWrite);
        if (tviPtr == IntPtr.Zero)
            throw new Exception("Could not allocate memory in owning process of TreeView", new Win32Exception());

        try
        {
            IntPtr textPtr = IntPtr.Add(tviPtr, tviSize);

            TVITEM tvi = new TVITEM();
            tvi.mask = TVIF_TEXT;
            tvi.hItem = hItem;
            tvi.cchTextMax = MY_MAXLVITEMTEXT;
            tvi.pszText = textPtr;

            IntPtr ptr = Marshal.AllocHGlobal(tviSize);
            try
            {
                Marshal.StructureToPtr(tvi, ptr, false);
                if (!WriteProcessMemory(process, tviPtr, ptr, tviSize, IntPtr.Zero))
                    throw new Exception("Could not write to memory in owning process of TreeView", new Win32Exception());
            }
            finally
            {
                Marshal.FreeHGlobal(ptr);
            }

            if (SendMessage(treeViewHwnd, isUnicode ? TVM_GETITEMW : TVM_GETITEMA, 0, tviPtr) != 1)
                throw new Exception("Could not get item data from TreeView");

            ptr = Marshal.AllocHGlobal(textSize);
            try
            {
                int bytesRead;
                if (!ReadProcessMemory(process, textPtr, ptr, textSize, out bytesRead))
                    throw new Exception("Could not read from memory in owning process of TreeView", new Win32Exception());

                if (isUnicode)
                    itemText = Marshal.PtrToStringUni(ptr, bytesRead / 2);
                else
                    itemText = Marshal.PtrToStringAnsi(ptr, bytesRead);
            }
            finally
            {
                Marshal.FreeHGlobal(ptr);
            }
        }
        finally
        {
            VirtualFreeEx(process, tviPtr, 0, FreeType.Release);
        }
    }
    finally
    {
        CloseHandle(process);
    }

    //char[] arr = itemText.ToCharArray(); //<== use this array to look at the bytes in debug mode

    return itemText;
}

