Hi, the code below works fine with files smaller than 2GB, but it also needs to be abe to handle larger files. I need to change the code to API but I have never really worked with those API before, only to get the size of files bigger than 2GB.
EOF doesn't work and I think I also need to use SetFilePointer, but it turns into a mess.
Can anyone please have a look at the code and tell what to change exactly? Thank you.
Original code:
Code:
Public Function HashFile(ByVal strFilename As String)
Dim fFile As String, sTheString As String, sTheHash As String, sFinalHash As String
Dim FF As Long, cCount As Long, cFile As Long, i As Integer
Dim b() As Byte
Const CHUNK_SIZE As Long = 9728000
Dim cCrypto As CryptKci.clsCryptoAPI
Set cCrypto = New CryptKci.clsCryptoAPI
sTheHash = ""
cFile = FileLen(strFilename)
FF = FreeFile()
ReDim b(0 To CHUNK_SIZE - 1)
Open strFilename For Binary Access Read Lock Write As #FF
Do While Not EOF(FF)
i = i + 1
If cFile < CHUNK_SIZE Then
ReDim b(0 To cFile - 1)
Get #FF, , b()
sTheString = StrConv(b(), vbUnicode)
sTheHash = sTheHash & cCrypto.CreateHash(sTheString, 2)
frmMain.txtHashSet.Text = frmMain.txtHashSet.Text & i & " - " & cCrypto.CreateHash(sTheString, 2) & " - " & cFile & vbCrLf
Exit Do
Else
Get #FF, , b()
sTheString = StrConv(b(), vbUnicode)
sTheHash = sTheHash & cCrypto.CreateHash(sTheString, 2)
frmMain.txtHashSet.Text = frmMain.txtHashSet.Text & i & " - " & cCrypto.CreateHash(sTheString, 2) & " - " & "9728000" & vbCrLf
End If
cFile = cFile - CHUNK_SIZE
DoEvents
Loop
Close #FF
sFinalHash = cCrypto.ConvertStringFromHex(sTheHash)
frmMain.txtHash.Text = cCrypto.CreateHash(sFinalHash, 2)
Set cCrypto = Nothing
End Function
New code:
Code:
Const FILE_BEGIN = 0
Const FILE_SHARE_READ = &H1
Const FILE_SHARE_WRITE = &H2
Const OPEN_EXISTING = 3
Const GENERIC_READ = &H80000000
Private Declare Function ReadFile Lib "kernel32" (ByVal hFile As Long, lpBuffer As Any, ByVal nNumberOfBytesToRead As Long, lpNumberOfBytesRead As Long, ByVal lpOverlapped As Any) As Long
Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" (ByVal lpFileName As String, ByVal dwDesiredAccess As Long, ByVal dwShareMode As Long, ByVal lpSecurityAttributes As Any, ByVal dwCreationDisposition As Long, ByVal dwFlagsAndAttributes As Long, ByVal hTemplateFile As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function SetFilePointer Lib "kernel32" (ByVal hFile As Long, ByVal lDistanceToMove As Long, lpDistanceToMoveHigh As Long, ByVal dwMoveMethod As Long) As Long
Private Declare Function GetFileSize Lib "kernel32" (ByVal hFile As Long, lpFileSizeHigh As Long) As Long
Public Function HashFile(ByVal strFilename As String)
Dim sTheString As String, sTheHash As String, sFinalHash As String
Dim i As Integer, b() As Byte
Dim hFile As Long, FileLenght As Long, Result As Long
Dim cCrypto As CryptKci.clsCryptoAPI
Set cCrypto = New CryptKci.clsCryptoAPI
Const CHUNK_SIZE As Long = 9728000
hFile = CreateFile(strFilename, GENERIC_READ, FILE_SHARE_READ Or FILE_SHARE_WRITE, ByVal 0&, OPEN_EXISTING, 0, 0)
sTheHash = ""
FileLenght = GetFileSize(hFile, 0)
SetFilePointer hFile, 0, 0, FILE_BEGIN
ReDim b(0 To CHUNK_SIZE - 1)
Do While Not EOF(hFile)
i = i + 1
If FileLenght < CHUNK_SIZE Then
ReDim b(0 To FileLenght - 1)
ReadFile hFile, b(1), UBound(b), Result, ByVal 0&
sTheString = StrConv(b(), vbUnicode)
sTheHash = sTheHash & cCrypto.CreateHash(sTheString, 2)
frmMain.txtHashSet.Text = frmMain.txtHashSet.Text & i & " - " & cCrypto.CreateHash(sTheString, 2) & " - " & FileLenght & vbCrLf
Exit Do
Else
ReadFile hFile, b(1), UBound(b), Result, ByVal 0&
sTheString = StrConv(b(), vbUnicode)
sTheHash = sTheHash & cCrypto.CreateHash(sTheString, 2)
frmMain.txtHashSet.Text = frmMain.txtHashSet.Text & i & " - " & cCrypto.CreateHash(sTheString, 2) & " - " & "9728000" & vbCrLf
End If
FileLenght = FileLenght - CHUNK_SIZE
DoEvents
Loop
sFinalHash = cCrypto.ConvertStringFromHex(sTheHash)
frmMain.txtHash.Text = cCrypto.CreateHash(sFinalHash, 2)
CloseHandle hFile
Set cCrypto = Nothing
End Function
I notice that in your original code you are using the 'old' method of opening and reading a file.
I'm not totally sure, but it may be worth making a reference to the 'Microsoft Scripting Runtime' and using the methods in there to try and read your file.
If you find my answers helpful, dont forget to rate me
to use API's to open, read and write files is not that difficult at all.
Attached is a API Module you can include into your project and do calls very simular to OPEN, Read, Write, and they will be doen via Windows API's.. Added is a extra funtion allowing you to cut files shorter (Set a new end of file) Something that VB6 commands lack..
for a working example of this api, follow the Hex-Editor link in my signature..
Hope this Helps...
Gremmy....
----- EDIT ------
Updated API Module on later post...
Last edited by GremlinSA; November 25th, 2006 at 01:16 PM.
Reason: Removed Attachement..
Special thanks to Lothar "the Great" Haensler, Chris Eastwood , dr_Michael, ClearCode, Iouri and
all the other wonderful people who made and make Codeguru a great place.
Come back soon, you Gurus.
Thanks for the suggestions. I'm trying GremlinSA's API module first and it makes it easier, but I'm still having some problems with it.
It returns the wrong size of files bigger than 4GB. My test file is 4.617.568.256 bytes (4.29GB), but API_OpenFile returns a file size of 322.597.374 bytes (File_Len in the code below).
Another problem I have is how to loop until the end of the file, because I can't use EOF. The final problem is how to read chunks of 9.728.000 bytes.
I need to read 9.728.000 bytes from the file, hash it, read the next 9.728.000 bytes, hash it, until the end of the file. If the last chunk is smaller than 9.728.000 bytes, then the Chunk_Size needs to be changed to the size of the last chunk or else the hash code will be wrong.
Code:
Option Explicit
Public File_Len As Long
Public File_Num As Long
Public Function HashFile(ByVal strFilename As String)
Dim Seek_Len As Long
Dim sString As String, sHash As String
Dim b() As Byte
Const Chunk_Size As Long = 9728000
API_OpenFile strFilename, File_Num, File_Len
Seek_Len = File_Len
'do until what?
If Seek_Len < Chunk_Size Then
API_ReadFile File_Num, Seek_Len, File_Len - Seek_Len, b()
sString = StrConv(b(), vbUnicode)
'sHash = sHash & cCrypto.CreateHash(sString, 2)
'frmMain.txtHashSet.Text = frmMain.txtHashSet.Text & i & " - " & cCrypto.CreateHash(sTheString, 2) & " - " & cFile & vbCrLf
'Exit Do
Else
API_ReadFile File_Num, Seek_Len, Chunk_Size, b()
sString = StrConv(b(), vbUnicode)
'sHash = sHash & cCrypto.CreateHash(sString, 2)
'frmMain.txtHashSet.Text = frmMain.txtHashSet.Text & i & " - " & cCrypto.CreateHash(sTheString, 2) & " - " & "9728000" & vbCrLf
End If
Seek_Len = Seek_Len - Chunk_Size
'Loop
End Function
I originaly wrote the module without using the High values in the API's mostly in these two
Code:
Private Declare Function SetFilePointer Lib "kernel32" (ByVal hFile As Long, ByVal lDistanceToMove As Long, lpDistanceToMoveHigh As Long, ByVal dwMoveMethod As Long) As Long
Private Declare Function GetFileSize Lib "kernel32" (ByVal hFile As Long, lpFileSizeHigh As Long) As Long
Private
so we just need to update them to use these values.
The filesize sub could be updated as follows..
Code:
Public Sub API_FileSize(ByVal FileNumber As Long, ByRef FileSize As Currency)
Dim FileSizeL As Long
Dim FileSizeH As Long
FileSizeH = 0
FileSizeL = GetFileSize(FileNumber, FileSizeH)
FileSize = FileSizeL + (FileSizeH * &H10000 * &H10000) ' &H100000000 is not valid in the VB IDE so we just split it..
End Sub
and the readfile sub can be updated as follows
Code:
Public Sub API_ReadFile(ByVal FileNumber As Long, ByVal Position As currency, ByRef BlockSize As Long, ByRef Data() As Byte)
Dim PosL As Long
Dim PosH As Long
Dim SizeRead As Long
Dim Ret As Long
PosL = Position And &HFFFFFFFF
PosH = (Position / &H10000 / &H10000) And &HFFFFFFFF
Ret = SetFilePointer(FileNumber, PosL, PosH, FILE_BEGIN)
Ret = ReadFile(FileNumber, Data(0), BlockSize, SizeRead, 0&)
BlockSize = SizeRead
End Sub
the writefile sub will need the same update.
this should give you an effective 922,337,203,685,477 Max filesize.
It's a bit late now, so i will test it better in the morning, and repost a corrected API Module...
Thanks. I tried the changes so far, but I get a "ByRef argument type mismatch" error on the line (API_FileSize FileH, FileSize) in the API_OpenFile sub.
I've changed them and the error message is gone, but now it returns 0 for the 4.29GB test file. With smaller files below 2GB it returns the correct filesize.
I removed API_SetEOF and API_WriteFile, because I don't need them.
VB has a very serious problem working with any number larger than a long, we looking at some real workarounds to get past the 4G limit..
Given enough time i'm sure that we could work out something...
theres even a module that our uncle Jonny wrote to handle this sort of poblem, i'm going to look into incorperating it into this module to get it to work for you..
It's essentially the same code as in my Module, with a little difference. Your still left with the task of splitting the file position variable into 2 - 32 bit words, and this is where most of us get stuck, considering that VB does not have a Unsigned 4 byte number Type....
As soon as a file passes the 2gig limit(2147483647 bytes) pasing the hex value to a Long would return a negative value (-2147483648), And this is the limitation that we have to work around...
Well i think ive done it, And the wife is a little peeved that i'v sitting infront of the PC at 2:00 in the morning, but anyways here it is...
I've added two small subs to convert a Currency value into two Long's and back, that will allow you to work with large files.. (tested in 1gig steps right up to 15 gig)...
Enjoy..
Please just let us know if it works 2 your satisfaction...
Gremmy....
--- Edit ----
New attachment on next post..
Last edited by GremlinSA; November 25th, 2006 at 01:13 PM.
Reason: Removed attachement
Yes, the filesize works fine now. Thank you very much for your help
The problem I have now is that I get an overflow error when I use the code below as a test and reach the 2GB.
I get the error on the line: "PosL = Position And &HFFFFFFFF" in the API_ReadFile sub. I tried to change some things myself, but I keep getting the overflow error.
Code:
Private b(9727999) As Byte
Private Sub Command1_Click()
Dim sString As String, cCount As Double, i As Long
Do Until i = 470
i = i + 1
API_ReadFile File_Num, cCount, 9728000, b()
cCount = CDbl(cCount) + CDbl(9728000)
DoEvents
Loop
End Sub
* The Best Reasons to Target Windows 8
Learn some of the best reasons why you should seriously consider bringing your Android mobile development expertise to bear on the Windows 8 platform.
Reply With Quote
..
Originally Posted by Cimperiali
