Comparing Executables and looking for byte offsets

Hi people:wave:
ok this is what i wanna know becuause i have no idea how to do it:(

1. I want toI compare every byte in between 2 executables
when I find a changed byte in case the executables are different Get the Offset of that byte and save it to a variable


2.count the number of different bytes between the 2 executables

ok i don't know if any you guys know this one prolly no but who knows maybe gurus can:bigyello:

Thanks for the help to whoever helps!

Regards,

That is fairly easy, but not as easy as giving a thread a decent title. In future please give your threads meaningful titles (eg: this one could be "How to compare two executable files").

Simply open both files for Binary Input (using the Open # statement, or FSO), then loop through them (both at the same time) reading bytes (using Get), and if they are different store the info you want.

Here's the code to load a file into a byte array.

VB Code:

Public Function GetFile(ByVal pstrFilename As String) As Byte()
Dim bytData()   As Byte
Dim intFile     As Integer
Dim lngLen      As Long
On Error GoTo ErrHandler
    If Dir(pstrFilename) = vbNullString Then
        Err.Raise vbObjectError, App.EXEName, "File not found."
    Else
        intFile = FreeFile
        Open pstrFilename For Binary Access Read Lock Read Write As #intFile
        lngLen = LOF(intFile)
        ReDim bytData(lngLen - 1) As Byte
        Get #intFile, 1, bytData()
        Close #intFile
        GetFile = bytData
    End If
    Exit Function
ErrHandler:
    Close #intFile
    Err.Raise Err.Number, Err.Source, Err.Description
End Function

Hope that helps.

Woka

ok but how do i know the offset of the byte that is different to the other Exe?

example

00401031 |. 817D 0C 100100>CMP DWORD PTR SS:[EBP+C],110
00401038 |. 75 5A JNZ SHORT blah.00401094

that's execuable one

00401031 |. 817D 0C 100100>CMP DWORD PTR SS:[EBP+C],110
00401038 |. 74 5A JE SHORT blah.00401095

excutable 2

as you can see byte 75 in exe 1 is different in exe 2 is 74 so tha offset of that byte changed would be 1039h

so how do i do that in vb ? get the offset of the byte changed in this case 1039h and store into variable
Thanks

P.S. Geek i changed my title :( sorry

VB Code:

Dim lngIndex As Long
Dim bytFile1() As Byte
Dim bytFile2() As Byte
   bytFile1 = GetFile("C:\Woof.exe")
   bytFile2 = GetFile("C:\Growl.exe")
   For lngIndex = 0 to UBound(bytFile1)
      If bytFile1(lngIndex) <> bytFile2(lngIndex) Then
         MsgBox "DIFFERENT!"
      End If
   Next lngIndex

Woka

Thanks Woka ;)

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