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Zip Files >2Gb in VO application

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2 months 1 week ago #1 by NickFriend
Zip Files >2Gb in VO application was created by NickFriend
Hi all,

I'm responsible for maintaining an old VO2.8 application that uses the even older V3 DynaZip component for zipping and unzipping files. We've hit an issue where a couple of clients need to create zip files for backups that exceed 2Gb, and DynaZip won't handle it.

Does anyone know a simple solution to this, or are we going to have to change the zip component? Does FabZip handle files >2Gb? We need to keep the work required to an absolute minimum as all our efforts are in .Net these days, but we need to resolve the issue for the clients as well.

TIA

Nick

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2 months 5 days ago #2 by Otto
Replied by Otto on topic Zip Files >2Gb in VO application
Can't you use 3 party tools and call them by commandline, like 7 zip?
see wiki

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2 months 5 days ago #3 by Fabrice
Replied by Fabrice on topic Zip Files >2Gb in VO application
Hi Nick,
it's been a long time since my latest changes with FabZip :), but as far as I remember the underground component is supporting files up to 4G and then you can also use the split-file capability.

But just to be sure, I will dust-off my VO28, check, and come back

Fab

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2 months 5 days ago #4 by NickFriend
Replied by NickFriend on topic Zip Files >2Gb in VO application
The thing is I try to spend as little time and effort as possible on this source code, as it just distracts from the main task at hand with our work in .Net.

I was hoping someone might have come up against this before and worked out a cunning solution that only takes 5 minutes to implement ;)

I think the most likely is a swap to FabZip, but unfortunately because of the horrible spaghetti code it means quite a lot of work and probably newly introduced bugs.

Nick

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2 months 5 days ago #5 by Fabrice
Replied by Fabrice on topic Zip Files >2Gb in VO application
First, I've still haven't checked, but...

maybe writing a wrapper around FabZip that mimics Dynazip could ease the work ? (but I'm sure you have already thought that)

Have you some UI feedback like progressBar, ... or is it a silent component ?

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2 months 5 days ago #6 by ArneOrtlinghaus
Replied by ArneOrtlinghaus on topic Zip Files >2Gb in VO application
Hello Nick,
it is the ZIP file format that has limitations.

For bigger archives we use the free program 7z.exe with the 7z-archive format already for many years. It handles excellently files of over 100GB!

7z can be completely controlled via command line parameters. I have attached examples how we call the program.

As an alternative there is always the GUI version 7zfm.exe for unzipping parts of archives.

Arne
Attachments:

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2 months 5 days ago #7 by MathiasHakansson
Replied by MathiasHakansson on topic Zip Files >2Gb in VO application
PKZIP supported files up to 4Gb (2^32 bytes) (both contained files and the zip file) until version 8. After that zip64 supported very large files (2^64 bytes). 4Gb is also the maximum file size in FAT32. Lots of zip-implementations only supports file sizes up to 2Gb, like Windows XP.

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2 months 5 days ago #8 by Fabrice
Replied by Fabrice on topic Zip Files >2Gb in VO application
Nick,
I've just tried using the Demo app of FabZip :
after few corrections due to mix between DWORD/LONG that was wrong for bigger file, I have been able to create a 2.8Gb file, with some ISO inside (like Ubuntu, Suse-Leaf,.. ), so I can confirm that FabZip is able to support >2Gb files :)

Cheers,
Fab

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2 months 5 days ago #9 by NickFriend
Replied by NickFriend on topic Zip Files >2Gb in VO application
Great Fab, thanks very much.

If I do have to reprogram this, at least I have a reliable solution available then.

Nick

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2 months 5 days ago #10 by ArneOrtlinghaus
Replied by ArneOrtlinghaus on topic Zip Files >2Gb in VO application
Hi Nick,

you should think on doing something like this.

It is the zip format that has limits! If I remember correctly, it should be something like 4 GB for a single zipped file and 8 GB for the total file or vice versa. In the Internet the correct limits can be retrieved. It can happen that a program creates zip files exceeding these limits without errors and instead it has created zip files that are corrupt and cannot be opened anymore. There are different programs like PKZIPC that have extended the limits but have created a new format that cannot be read by standard zip functions. So better change the format if you need bigger sizes. Having multi media files or complex Office documents the installations have grown quickly.

Arne

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2 months 2 days ago #11 by NickFriend
Replied by NickFriend on topic Zip Files >2Gb in VO application
Hi Fab,

We're edging towards a complete replacement with FabZip. Two questions:
1. Looking on your website, I found an old news item about FabZip from 2006 where you say that it's stuck with a 2Gb limit due to the underlying components, and that there's no solution. Checking the latest download, I see the Zipdll.dll and Unzdll.dll files are dated 2004... so presumably are still the same ones as when you decided 2Gb was the limit. But of course you've just tested it now with >2Gb. Not sure what to make of that ;-)
2. We need progress bars with such big time consuming processes - does FabZip support this?

Thanks

Nick

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2 months 2 days ago #12 by ArneOrtlinghaus
Replied by ArneOrtlinghaus on topic Zip Files >2Gb in VO application
In Wikipedia under
en.wikipedia.org/wiki/Zip_(file_format)
is a good article about the limitations of the ZIP format and Zip 64 bit extensions.

One of my colleagues told me that the Dotnet framework zip facilities should be able to use the ZIP 64 Bit format also when started by a 32 bit process. But at least Windows Vista is needed.

Arne

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2 months 2 days ago #13 by NickFriend
Replied by NickFriend on topic Zip Files >2Gb in VO application
Hi Arne,

Thanks for the info!

Nick

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2 months 2 days ago #14 by Fabrice
Replied by Fabrice on topic Zip Files >2Gb in VO application
Nick,
I can send you all the AEFs I've used in order to proceed to test after your message :
I had to make some corrections in order to support 2Gb limit : I was using WORD/LONG at sensible offset calculation places, and it was crashing my own code, not the Unzip/Zip DLLs

The lib comes in 2 flavors : GUI or NoGui
In both versions, you can register to some events,that will give you progress info; The GUI sample app is using that with progress Bars, so you can have a look.

I'm not sure to have your email adress : Can you send me a mail to fabrice at xsharp.eu ?
I will then send you all the files.

Cheers,
Fab

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2 months 2 days ago #15 by ArneOrtlinghaus
Replied by ArneOrtlinghaus on topic Zip Files >2Gb in VO application
I cannot resist adding my comments:
If it crashed at arriving 2GB when using LONG then it should crash again at 4 GB using DWORD...

Arne

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2 months 2 days ago #16 by NickFriend
Replied by NickFriend on topic Zip Files >2Gb in VO application
But that gives us 2Gb of breathing space whilst we replace the whole application with it's new .Net version!!!

Nick

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