CRC32Fingerprint Question

[webbmeister]

Is there any way of Using CRC32Fingerprint to verify the interity of a ZIP file?

[horst]

Is there any way of Using CRC32Fingerprint to verify the interity of a ZIP file?

Do you know where to find the CRC32's in a ZIP file?

[Trond]

This is an example program written for Rapid-Q, it should be possible to translate it to PureBasic. It shows the CRC32 of each file.

Code: Select all

' Simple .ZIP viewer (doesn't extract or anything useful like that).
' You're free to modify and distribute the code without restrictions.
' Written in Rapid-Q by William Yu
' Demonstrates QOpenDialog, QFileStream, QListView, QMainMenu, QMenuItem
'              and QImageList.

$APPTYPE GUI
$TYPECHECK ON
$INCLUDE "RAPIDQ.INC"

$RESOURCE ICO_ZIP AS "ZIP.ICO"
$RESOURCE ICO_APP AS "APP.ICO"

DECLARE SUB ZipView (ZIPFile AS STRING)
DECLARE SUB FormResize
DECLARE SUB OpenClick
DECLARE SUB ExitClick
DECLARE SUB IconClick
DECLARE SUB SmallIconClick
DECLARE SUB ReportClick
DECLARE SUB ItemDblClick

CONST SIG = &H04034B50         ' ZIP Signature/ID

TYPE ZFHeader
  Signature AS LONG
  Version AS WORD
  GPBFlag AS WORD              ' ?
  Compress AS WORD             ' Compression types
  DateTime AS LONG             ' Packed format
  CRC32 AS LONG
  CSize AS LONG                ' Compressed size
  USize AS LONG                ' Uncompressed size
  FileNameLen AS LONG
END TYPE

TYPE PackedDateType            ' I think this is it:
  Year AS SHORT                ' 7 bits
  Month AS BYTE                ' 4 bits
  Day AS BYTE                  ' 5 bits
  Hour AS BYTE                 ' 5 bits
  Minute AS BYTE               ' 6 bits
  Secs AS BYTE                 ' 5 bits
END TYPE                       ' Total = 32 bits

DIM CompType(0 TO 9) AS STRING
    CompType(0) = "Stored"
    CompType(1) = "Shrunk"
    CompType(2) = "Reduced1"
    CompType(3) = "Reduced2"
    CompType(4) = "Reduced3"
    CompType(5) = "Reduced4"
    CompType(6) = "Imploded"
    CompType(7) = "Defalted"
    CompType(8) = "DeflatN"      '' Could be DeflatX as well...
    CompType(9) = "DeflatX"

DIM OpenItem AS QMenuItem
    OpenItem.Caption = "&Open"
    OpenItem.OnClick = OpenClick
DIM BreakItem AS QMenuItem
    BreakItem.Caption = "-"
DIM ExitItem AS QMenuItem
    ExitItem.Caption = "E&xit"
    ExitItem.OnClick = ExitClick
DIM IconItem AS QMenuItem
    IconItem.Caption = "vs&Icon"
    IconItem.RadioItem = True
    IconItem.OnClick = IconClick
DIM SmallIconItem AS QMenuItem
    SmallIconItem.Caption = "vs&SmallIcon"
    SmallIconItem.RadioItem = True
    SmallIconItem.OnClick = SmallIconClick
DIM ReportItem AS QMenuItem
    ReportItem.Caption = "vs&Report"
    ReportItem.RadioItem = True
    ReportItem.Checked = True
    ReportItem.OnClick = ReportClick


DIM FileMenu AS QMenuItem
    FileMenu.Caption = "&File"
    FileMenu.AddItems OpenItem, BreakItem, ExitItem
DIM ViewMenu AS QMenuItem
    ViewMenu.Caption = "&View"
    ViewMenu.AddItems IconItem, SmallIconItem, ReportItem

DIM ImageList1 AS QImageList

    ImageList1.Height = 32
    ImageList1.Width = 32
    ImageList1.AddICOHandle ICO_APP
    ImageList1.AddICOHandle ICO_ZIP

DIM ImageList2 AS QImageList            ' Scale 16x16
    ImageList2.Height = 16
    ImageList2.Width = 16
    ImageList2.AddICOHandle ICO_APP
'    ImageList2.AddICOHandle ICO_ZIP
    ImageList2.AddICOFile(ImageList1.GetICO(1))


CREATE Form AS QForm
  ICOHandle = ICO_ZIP
  Center
  OnResize = FormResize
  Height = 330
  Width = 525
  Caption = "Simple .ZIP Viewer for Rapid-Q"
  CREATE MainMenu AS QMainMenu
    AddItems FileMenu, ViewMenu
  END CREATE
  CREATE ListView AS QListView
    ColumnClick = False
    HotTrack = 1
    Width = Form.ClientWidth
    Height = Form.ClientHeight
    SmallImages = ImageList2
    LargeImages = ImageList1
    ViewStyle = vsReport
    AddColumns "FileName","Length","Method","Size","Rate","Date","Time","CRC-32"
    Column(0).Width = 200
    Column(4).Width = 40
    Column(5).Width = 70
    Column(7).Width = 70
    OnDblClick = ItemDblClick
  END CREATE
  ShowModal
END CREATE


'------------------------------------------------------------------

SUB ZipView (ZIPFile AS STRING)
  DIM Hdr      AS ZFHeader
  DIM ZF       AS QFileStream
  DIM PD       AS PackedDateType
  DIM FileName AS STRING
  DIM Index    AS INTEGER

  IF ZF.Open(ZIPFile, fmOpenRead) = False THEN
    ShowMessage("Problem with reading "+ZIPFile)
    EXIT SUB
  END IF

  ListView.Clear
  Hdr.Signature = ZF.ReadNum(4)

  Index = 0
  WHILE Hdr.Signature = SIG
    Hdr.Version  = ZF.ReadNum(2)
    Hdr.GPBFlag  = ZF.ReadNum(2)
    Hdr.Compress = ZF.ReadNum(2)
    Hdr.DateTime = ZF.ReadNum(4)
    Hdr.CRC32 = ZF.ReadNum(4)
    Hdr.CSize = ZF.ReadNum(4)
    Hdr.USize = ZF.ReadNum(4)
    Hdr.FileNameLen = ZF.ReadNum(4)

    FileName = ZF.ReadStr(Hdr.FileNameLen)

    PD.Year = ((Hdr.DateTime SHR 25) AND &H7F) + 1980
    PD.Month = (Hdr.DateTime SHR 21) AND &H0F
    PD.Day = (Hdr.DateTime SHR 16) AND &H1F
    PD.Hour = (Hdr.DateTime SHR 11) AND &H1F
    PD.Minute = (Hdr.DateTime SHR 5) AND &H3F
    PD.Secs = Hdr.DateTime AND &H1F
    ListView.AddItems FileName
    IF INSTR(UCASE$(FileName), ".ZIP") THEN
      ListView.Item(Index).ImageIndex = 1
    END IF
    ListView.AddSubItem Index, STR$(Hdr.USize)
    ListView.AddSubItem Index, CompType(Hdr.Compress)
    ListView.AddSubItem Index, STR$(Hdr.CSize)
    IF Hdr.USize = 0 THEN
      ListView.AddSubItem Index, "----"
    ELSE
      ListView.AddSubItem Index, STR$(INT((Hdr.USize - Hdr.CSize) / Hdr.USize * 100))+"%"
    END IF
    ListView.AddSubItem Index, STR$(PD.Month)+"-"+STR$(PD.Day)+"-"+STR$(PD.Year)
    ListView.AddSubItem Index, STR$(PD.Hour)+":"+STR$(PD.Minute)
    ListView.AddSubItem Index, LCASE$(HEX$(Hdr.CRC32))
    ZF.Seek(Hdr.CSize, soFromCurrent)
    Hdr.Signature = ZF.ReadNum(4)
    Index = Index + 1
  WEND

  IF Index = 0 THEN
     '-- Likely not a .ZIP file
     ShowMessage(ZIPFile+" is not a valid ZIP file!")
  END IF
END SUB

SUB OpenClick
  DIM OpenDialog AS QOpenDialog

  OpenDialog.InitialDir = CurDir$
  OpenDialog.Filter = "ZIP Files (*.zip)|*.zip|All Files (*.*)|*.*"

  IF OpenDialog.Execute THEN
    ZipView(OpenDialog.FileName)
  END IF
END SUB

SUB ExitClick
  Form.Close
END SUB

SUB FormResize
  ListView.Height = Form.ClientHeight
  ListView.Width = Form.ClientWidth
END SUB

SUB IconClick
  IconItem.Checked = True
  ListView.ViewStyle = vsIcon
END SUB

SUB SmallIconClick
  SmallIconItem.Checked = True
  ListView.ViewStyle = vsSmallIcon
END SUB

SUB ReportClick
  ReportItem.Checked = True
  ListView.ViewStyle = vsReport
END SUB

SUB ItemDblClick
  IF ListView.ItemIndex >= 0 THEN
    ShowMessage("Can't extract "+ListView.Item(ListView.ItemIndex).Caption)
  END IF
END SUB

[webbmeister]

Thank for the replies. Maybe I asked the wrong question. What i should have asked is CRCFingerprint32 suitable for verifying the integrity of a zip file? - or is there a better method?

[srod]

**Off topic: first time I've seen any rapidQ code; looks very nice, very tight.

[Trond]

Thank for the replies. Maybe I asked the wrong question. What i should have asked is CRCFingerprint32 suitable for verifying the integrity of a zip file? - or is there a better method?

You mean like verifying the entire zip file at once? Like, first getting a checksum right after the zip file is created and then get the checksum again after the file has been thrown around to check if the file is still ok? For that you should use md5.

[webbmeister]

Thank for the replies. Maybe I asked the wrong question. What i should have asked is CRCFingerprint32 suitable for verifying the integrity of a zip file? - or is there a better method?

You mean like verifying the entire zip file at once? Like, first getting a checksum right after the zip file is created and then get the checksum again after the file has been thrown around to check if the file is still ok? For that you should use md5.

Yeah that's what I'm after. Something to uncompress a "chunk" of the zip file to memory and compare this with the same "chunk" of the original file(s) that have been added to see if these match

[gnozal]

You can get the CRC32 for each file in the ZIP

Code: Select all

; PureZIP example
If PureZIP_Archive_Read("c:\PureBasic400\Program\Test.zip")
  ReturnValue.l = PureZIP_Archive_FindFirst() = #UNZ_OK
  While ReturnValue = #UNZ_OK 
    Debug PureZIP_Archive_FileInfo(@myFileinfo.PureZIP_FileInfo)
    Debug "Filename: " + myFileinfo\FileName
    Debug "Compressed Size: " + Str(myFileinfo\CompressedSize)
    Debug "Uncompressed Size: "+ Str(myFileinfo\unCompressedSize)
    Debug "CRC32 : "+ Hex(myFileinfo\crc32) ; <------------ CRC of uncompressed file
    ReturnValue = PureZIP_Archive_FindNext()
  Wend
  PureZIP_Archive_Close()
EndIf

then use CRCFingerprint32() on the original file and compare both results.
Note that ZLIB also provides a CRC32 function.

[webbmeister]

Thanks for Gnozal. Is Purezip compatible with PB v4 ?

[gnozal]

Thanks for Gnozal. Is Purezip compatible with PB v4 ?

Yes, it should also work with PB4 now.

Download PureZIP
PB3.94 : http://people.freenet.de/gnozal/PureZIP.zip
PB4.0x : http://people.freenet.de/gnozal/PureZIP_.zip

[webbmeister]

Thanks for Gnozal. Is Purezip compatible with PB v4 ?

Yes, it should also work with PB4 now.

Download PureZIP
PB3.94 : http://people.freenet.de/gnozal/PureZIP.zip
PB4.0x : http://people.freenet.de/gnozal/PureZIP_.zip

I've just tried the two links above - no joy. Are the addresses correct?

[gnozal]

I've just tried the two links above - no joy. Are the addresses correct?

Yes, it works, just tested.

[Dare]

Links works here.

[webbmeister]

The link now works - must have been a glitch. Ran installer OK. Loaded the Unzip example supplied within. When i try to compile I get the following message.....



Any Ideas?

[gnozal]

Just compiled example 'PureZIP_TEST_MiniUNZIP.pb' : no problem with PB4.00 final for me.