VB - Klasse für SimpleFileVerification (SFV)

Imports System.IO

''' <summary>
''' Diese Klasse verarbeitet SFV Dateien.
''' Dabei wird eine SFV Datei geöffnet und es werden von allen aufgelisteten Dateien
''' CRC32 Summen erstellt und diese werden dann mit den Summen aus der SFV Datei vergleichen.
''' Bei Fehlenden, Kaputten und Sauberen Dateien wird jeweils das dazugehörige Event aufgerufen.
''' SFV Dateien müssen das Standardformat besitzen: "Dateiname.dat ABCD1234" wobei der CRC32 Hash
''' in der SFV Datei immer 8 Zeichen lang sein muss. In einigen Fällen hat ein CRC32 Hash nur 7 Zeichen,
''' dann sollte am Anfang des Hashes eine 0 angehängt werden also "0ABC1234" statt "ABC1234".
''' </summary>
''' <remarks>Geschrieben von Tim Hartwig (Januar 08)</remarks>
Public Class SimpleFileVerification
    Private mSFVFile As String

    ''' <summary>
    ''' Tritt ein wenn eine Datei in der SFV Liste aufgeführt ist, aber nicht vorhanden ist.
    ''' </summary>
    Public Event FileIsMissing(ByVal sender As Object, ByVal e As SFVEventArgs)

    ''' <summary>
    ''' Tritt ein wenn die Datei nicht die vorgegebene Prüfsumme aus der SFV Datei hat.
    ''' </summary>
    Public Event FileIsCorrupted(ByVal sender As Object, ByVal e As SFVEventArgs)

    ''' <summary>
    ''' Tritt immer ein wenn eine Datei in Ordnung ist.
    ''' </summary>
    Public Event FileIsClean(ByVal sender As Object, ByVal e As SFVEventArgs)

    ''' <summary>
    ''' Tritt ein wenn die überprüfung der aktuellen SFV Datei fertiggestellt ist.
    ''' </summary>
    Public Event Finished(ByVal sender As Object)

    ''' <summary>
    ''' Die SFV Datei in der die Prüfdaten drin stehen.
    ''' </summary>
    Public Property SFVFile() As String
        Get
            Return mSFVFile
        End Get
        Set(ByVal value As String)
            mSFVFile = value
        End Set
    End Property

    Sub New()
        CreateCRC32Table()
    End Sub

    Sub New(ByVal nSFVFile As String)
        mSFVFile = nSFVFile
        CreateCRC32Table()
    End Sub

    ''' <summary>
    ''' Beginnt die prüfung der SFV Datei.
    ''' </summary>
    Public Sub Start()
        Dim Data() As String = File.ReadAllLines(mSFVFile)
        Dim CurrExpectedHash As String = ""
        Dim CurrCalculatedHash As String = ""
        Dim CurrFileNameToCheck As String = ""
        Dim SFVFilePath As String = Path.GetDirectoryName(mSFVFile) & "\"

        For i As Integer = 0 To Data.Length - 1
            If Data(i) IsNot String.Empty And Not Data(i).StartsWith(";") Then
                CurrFileNameToCheck = SFVFilePath & Data(i).Substring(0, Data(i).Length - 9)

                If File.Exists(CurrFileNameToCheck) = False Then
                    RaiseEvent FileIsMissing(Me, New SFVEventArgs(CurrFileNameToCheck, "", ""))
                Else
                    CurrExpectedHash = Data(i).Substring(Data(i).Length - 8, 8).ToUpper.Replace(" ", "")
                    CurrCalculatedHash = ProcessFile(CurrFileNameToCheck).ToUpper

                    If CurrCalculatedHash.Length <> 8 Then CurrCalculatedHash = "0" & CurrCalculatedHash

                    If CurrExpectedHash = CurrCalculatedHash Then
                        RaiseEvent FileIsClean(Me, New SFVEventArgs(CurrFileNameToCheck, CurrExpectedHash, CurrCalculatedHash))
                    Else
                        RaiseEvent FileIsCorrupted(Me, New SFVEventArgs(CurrFileNameToCheck, CurrExpectedHash, CurrCalculatedHash))
                    End If
                End If
            End If
        Next

        RaiseEvent Finished(Me)
    End Sub

#Region "CRC32"
    Private CRC32Table() As Integer
    Private Const CRC32Polynomial As Integer = &HEDB88320

    Public Function ProcessFile(ByVal FileName As String) As String
        Dim FS As FileStream = New FileStream(FileName, FileMode.Open, _
        FileAccess.Read, FileShare.Read, 1048576)
        Dim CRC32Result As Integer = &HFFFFFFFF
        Dim Buffer(4096) As Byte
        Dim ReadSize As Integer = 4096
        Dim Count As Integer = FS.Read(Buffer, 0, ReadSize)
        Dim Lookup As Integer

        Do While (Count > 0)
            For i As Integer = 0 To Count - 1
                Lookup = (CRC32Result And &HFF) Xor Buffer(i)
                CRC32Result = ((CRC32Result And &HFFFFFF00) \ &H100) And &HFFFFFF
                CRC32Result = CRC32Result Xor CRC32Table(Lookup)
            Next i
            Count = FS.Read(Buffer, 0, ReadSize)
        Loop

        Return Hex(Not (CRC32Result)).ToString
    End Function

    Private Sub CreateCRC32Table()
        Dim DWCRC As Integer
        ReDim CRC32Table(256)

        For i As Integer = 0 To 255
            DWCRC = i
            For n As Integer = 8 To 1 Step -1
                If (DWCRC And 1) Then
                    DWCRC = ((DWCRC And &HFFFFFFFE) \ 2&) And &H7FFFFFFF
                    DWCRC = DWCRC Xor CRC32Polynomial
                Else
                    DWCRC = ((DWCRC And &HFFFFFFFE) \ 2&) And &H7FFFFFFF
                End If
            Next
            CRC32Table(i) = DWCRC
        Next i
    End Sub
#End Region
End Class

Public Class SFVEventArgs
    Private mFileName As String
    Private mExpectedHash As String
    Private mCalculatedHash As String

    Public Property FileName() As String
        Get
            Return mFileName
        End Get
        Set(ByVal value As String)
            mFileName = value
        End Set
    End Property

    Public Property ExpectedHash() As String
        Get
            Return mExpectedHash
        End Get
        Set(ByVal value As String)
            mExpectedHash = value
        End Set
    End Property

    Public Property CalculatedHash() As String
        Get
            Return mCalculatedHash
        End Get
        Set(ByVal value As String)
            mCalculatedHash = value
        End Set
    End Property

    Sub New(ByVal nFileName As String, ByVal nExpectedHash As String, ByVal nCalculatedHash As String)
        mFileName = nFileName
        mExpectedHash = nExpectedHash
        mCalculatedHash = nCalculatedHash
    End Sub
End Class