VB6 to VB.Net

I have a code which I have translated the majority of for use in vb.net.

It requires: 3 Labels, 3 Text Boxes, and 1 Button (named command1)

It also has no errors in the errors list, so hopefully it should be an easy fix for the
average/experienced coder.

CODE: (full)

Code:

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Public Class Form1

    Structure OSVERSIONINFO
        Public dwOSVersionInfoSize As Long
        Public dwMajorVersion As Long
        Public dwMinorVersion As Long
        Public dwBuildNumber As Long
        Public dwPlatformId As Long
        Public szCSDVersion As String
    End Structure

    Structure MEMORY_BASIC_INFORMATION ' 28 bytes
        Public BaseAddress As Long
        Public AllocationBase As Long
        Public AllocationProtect As Long
        Public RegionSize As Long
        Public State As Long
        Public Protect As Long
        Public lType As Long
    End Structure

    Structure SYSTEM_INFO ' 36 Bytes
        Public dwOemID As Long
        Public dwPageSize As Long
        Public lpMinimumApplicationAddress As Long
        Public lpMaximumApplicationAddress As Long
        Public dwActiveProcessorMask As Long
        Public dwNumberOrfProcessors As Long
        Public dwProcessorType As Long
        Public dwAllocationGranularity As Long
        Public wProcessorLevel As Integer
        Public wProcessorRevision As Integer
    End Structure

    Private Declare Function GetVersionEx Lib "kernel32" Alias "GetVersionExA" (ByVal LpVersionInformation As OSVERSIONINFO) As Long
    Private Declare Function VirtualQueryEx& Lib "kernel32" (ByVal hProcess As Long, ByVal lpAddress As Long, ByVal lpBuffer As MEMORY_BASIC_INFORMATION, ByVal dwLength As Long)
    Private Declare Sub GetSystemInfo Lib "kernel32" (ByVal lpSystemInfo As SYSTEM_INFO)
    Private Declare Function OpenProcess Lib "kernel32" (ByVal dwDesiredAccess As Long, ByVal blnheritHandle As Long, ByVal dwAppProcessId As Long) As Long
    Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
    Private Declare Function ReadProcessMemory Lib "kernel32" (ByVal hProcess As Long, ByVal lpBaseAddress As Long, ByRef lpBuffer As String, ByVal nSize As Long, ByVal lpNumberOfBytesWritten As Long) As Long
    Private Declare Function WriteProcessMemory Lib "kernel32" (ByVal hProcess As Long, ByVal lpBaseAddress As Long, ByRef lpBuffer As String, ByVal nSize As Long, ByVal lpNumberOfBytesWritten As Long) As Long

    Private Declare Function GetWindowThreadProcessId Lib "user32" (ByVal hWnd As Long, ByRef lpdwProcessId As Long) As Long
    Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As IntPtr
    Private Declare Function GetParent Lib "user32" (ByVal hWnd As Long) As Long
    Private Declare Function GetWindow Lib "user32" (ByVal hWnd As Long, ByVal wCmd As Long) As Long
    Const GW_HWNDNEXT = 2

    Private Declare Function InvalidateRect Lib "user32" (ByVal hWnd As Long, ByVal lpRect As Long, ByVal bErase As Long) As Long
    Const PROCESS_VM_READ = (&H10)
    Const PROCESS_VM_WRITE = (&H20)
    Const PROCESS_VM_OPERATION = (&H8)
    Const PROCESS_QUERY_INFORMATION = (&H400)
    Const PROCESS_READ_WRITE_QUERY = PROCESS_VM_READ + PROCESS_VM_WRITE + PROCESS_VM_OPERATION + PROCESS_QUERY_INFORMATION
    Const MEM_PRIVATE& = &H20000
    Const MEM_COMMIT& = &H1000

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Try
            Me.Text = "Memory Scanner"
            Label1.Text = "Start application:"
            Label2.Text = "String to find:"
            Label3.Text = "Replace with:"
            TextBox1.Text = "Calc.exe"
            TextBox2.Text = "Backspace"
            TextBox3.Text = "VB-O-Matic"
            Command1.Text = "&Launch It!"
        Catch ex As Exception
            MsgBox(ErrorToString, ex.ToString)
        End Try
    End Sub

    Private Sub B1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Command1.Click
        Try
            Dim pid As Long, hProcess As Long, hWin As Long
            Dim lpMem As Long, ret As Long, lLenMBI As Long
            Dim lWritten As Long, CalcAddress As Long, lPos As Long
            Dim sBuffer As String
            Dim sSearchString As String, sReplaceString As String
            Dim si As SYSTEM_INFO
            Dim mbi As MEMORY_BASIC_INFORMATION
            sSearchString = TextBox2.Text
            sReplaceString = TextBox3.Text & Chr(0)
            pid = Shell(TextBox1.Text) 'launch application (calc.exe in this sample)
            hWin = InstanceToWnd(pid) 'get handle of launched window - only to repaint it after changes
            'Open process with required access
            hProcess = OpenProcess(PROCESS_READ_WRITE_QUERY, False, pid)
            lLenMBI = Len(mbi)
            'Determine applications memory addresses range
            Call GetSystemInfo(si)
            lpMem = si.lpMinimumApplicationAddress
            'Scan memory
            Do While lpMem < si.lpMaximumApplicationAddress
                mbi.RegionSize = 0
                ret = VirtualQueryEx(hProcess, lpMem, mbi, lLenMBI)
                If ret = lLenMBI Then
                    If ((mbi.lType = MEM_PRIVATE) And (mbi.State = MEM_COMMIT)) Then ' this block is In use by this process
                        If mbi.RegionSize > 0 Then
                            sBuffer = mbi.RegionSize
                            'Read region into string
                            ReadProcessMemory(hProcess, mbi.BaseAddress, sBuffer, mbi.RegionSize, lWritten)
                            'Check if region contain search string
                            lPos = InStr(1, sBuffer, sSearchString, vbTextCompare)
                            If lPos Then
                                CalcAddress = mbi.BaseAddress + lPos
                                Me.Show()
                                ret = MsgBox("Search string was found at address " & CalcAddress & "." & vbCrLf & "Do you want to replace it?", vbInformation + vbYesNo, "VB-O-Matic")
                                If ret = vbYes Then
                                    'Replace string in virtual memory
                                    Call WriteProcessMemory(hProcess, CalcAddress - 1, sReplaceString, Len(sReplaceString), lWritten)
                                    'Redraw window
                                    InvalidateRect(hWin, 0, 1)
                                End If
                                Exit Do
                            End If
                        End If
                    End If
                    'Increase base address for next searching cicle. Last address may overhead max Long value (Windows use 2GB memory, which is near max long value), so add Error checking
                    lpMem = mbi.BaseAddress + mbi.RegionSize
                Else
                    Exit Do
                End If
            Loop
        Catch ex As Exception
            MsgBox(ErrorToString, ex.ToString)
        End Try
    End Sub

    Private Function InstanceToWnd(ByVal target_pid As Long) As Long
        Try
            Dim test_hwnd As Long
            Dim test_pid As Long
            Dim test_thread_id As Long
            test_hwnd = FindWindow(0&, 0&)
            Do While test_hwnd <> 0
                If GetParent(test_hwnd) = 0 Then
                    test_thread_id = GetWindowThreadProcessId(test_hwnd, test_pid)
                    If test_pid = target_pid Then
                        InstanceToWnd = test_hwnd
                        Exit Do
                    End If
                End If
                test_hwnd = GetWindow(test_hwnd, GW_HWNDNEXT)
            Loop
        Catch ex As Exception
            MsgBox(ErrorToString, ex.ToString)
        End Try
    End Function

End Class

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The errors received when running he application are:

LINE: hProcess = OpenProcess(PROCESS_READ_WRITE_QUERY, False, pid)

Code:

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Managed Debugging Assistant 'PInvokeStackImbalance' has detected a problem in 'C:\Documents and Settings\User X\My Documents\Visual Studio 2010\Projects\Memory Scanner\Memory Scanner\bin\Debug\Memory Scanner.vshost.exe'.
Additional Information: A call to PInvoke function 'Memory Scanner!Memory_Scanner.Form1::OpenProcess' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.

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LINE: Call GetSystemInfo(si)

Code:

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An unhandled exception of type 'System.AccessViolationException' occurred in Memory Scanner.exe

Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

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Then the application closes.

What is supposed to do is:

Command1 (Button1) Clicked: Open the calulator, look for the string in backspace,
and change it to VB-O-Matic.

Help is appreciated, Thanks. :wave:

It's all in your declarations (probably). Try looking them up on pinvoke.net and you'll see that there are some variations of variable type and so on. Even then you might need to experiment a bit.

Having said that, a lot of the stuff that you did in API in VB6 can now be done with native commands in VB.Net. It might be worth, as a learning exercise if nothing else, starting the whole project from scratch.

I changed the openprocess to:

Code:

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Private Declare Function OpenProcess Lib "kernel32" (ByVal dwDesiredAccess As Integer, ByVal blnheritHandle As Boolean, ByVal dwAppProcessId As Integer) As IntPtr

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Seems to work.. Now I just need to resolve this:

LINE: Call GetSystemInfo(si)

Code:

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Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

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Windows API functions almost exclusively work with 32-bit numbers. In VB6, the Long data type was 32-bit and the Integer data type was 16-bit. In VB.NET, the Long data type is 64-bit and the Integer data type is 32-bit. If you have an API declaration that uses Long then it was almost certainly written for VB6. In VB.NET, you should change the Longs to Integers. Also, whenever a value represents a pointer or a handle, while it's OK to use Integer, it's more correct to use IntPtr.

very helpful info jmcilhinney, i may try to update it again. thanks :)