Uncompressing 64-bit Zip Files?

  • Thread starter Thread starter ScottO
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ScottO

Is anyone aware of native dotnet code to uncompress 64-bit Zip files?
Everything I have found so far can only uncompress files inside a zip file
up to 9Gig.

Any thoughts?

Thanks in advanced,

Scott
 
Hi ScottO,

Thanks for posting in this group.

Can you tell me what does your "64-bit" zip file mean? Also, what is "9Gig"?

Thank you for your patience and cooperation. If you have any questions or
concerns, please feel free to post it in the group. I am standing by to be
of assistance.

Best regards,
Jeffrey Tan
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.
 
Jeff,



To be more specific Winzip 9.0 can compress files over 4 Gig now. It uses
"64-bit extensions". PK 2.0's normal limitation is 4 Gig.
http://www.winzip.com/wzdic.htm



I tried to uncompress a file that contained over 9 gigs of data using
SharpZipLib <big shout out!!!> but it throw an error after 7.6 Gig. After we
made some INTs to LONGs and some other modification the entire 9 Gig
uncompressed. Next steps are to see if it really works or just pretended to
work <grin>. Then we'll try to make the same changes to the compression
routine. The GZip library in SharpZipLib might allow me to compress a 9 Gig
but I haven't tested it yet.



It is truly AMAZING to take a 7.7 Gig ASCII file (with a lot of spaces in
it) compress down to 200 MB. Then compress the compressed file a second time
to a mere 4.5 MB!



I think I am good shape now but any comments on compression and .NET are
greatly appreciated.



Scott
 
Jeffrey Tan said:
Hi ScottO,

Thanks for posting in this group.

Can you tell me what does your "64-bit" zip file mean? Also, what is
"9Gig"?

Thank you for your patience and cooperation. If you have any
questions or concerns, please feel free to post it in the group. I am
standing by to be of assistance.

Best regards,
Jeffrey Tan
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no
rights.
Click to expand...


I think is means deflate64 an extension to the Zip file format to allow
extremely large files to be handled (2^64). It uses a 64k window for
compressing as well as extensions to the file format.

-jr-
 
Hi Scott,

Thanks very much for your feedback.

I am glad you have workaround this issue. I think the reason of needing
change "int" to "long" may be that, long is System.Int64 type in .Net, and
it is 64-bit, when applying compress algorithm, "int" may overflow for big
file.

For your other compress issue, I think it is due to the algorithm. It seems
that SharpZipLib is a free and open source library. You may discover its
root cause in the source code.

Also, I think you may consult the SharpZipLib related issue at that
compony's web site, you may get more help there, because more people use
SharpZipLib there. :-)

Thank you for your patience and cooperation. If you have any questions or
concerns, please feel free to post it in the group. I am standing by to be
of assistance.

Best regards,
Jeffrey Tan
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.
 
Hi Scott,

If you are interested in good compression then you might try Bzip2
which tends to compress a little better than Zip compressors. I think
it will handle very large files also.

I am also interested in the changes you made to SharpZipLib which I use
a little myself.


Cheers,

-jr-
 
I'm using SharpZipLib now and I was curious if you found PKZip to be
faster then SharpZipLib when called from C#. I'm not too concern
about size I need speed. I'm also only working with byte arrays not
files.

If anybody has any other suggestions on the fastest compression
library I would greatly appreciate it.
 
Hi Scott,

Does our reply make sense to you? Do you still have any concern on this
issue?

Please feel free to post. Thanks

Best regards,
Jeffrey Tan
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.
 
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