Zip Files >2Gb in VO application

NickFriend · Post by **NickFriend** » Fri Oct 05, 2018 9:30 am

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

Otto · Post by **Otto** » Mon Oct 08, 2018 4:39 am

Can't you use 3 party tools and call them by commandline, like 7 zip?
see wiki

Fabrice · Post by **Fabrice** » Mon Oct 08, 2018 7:42 am

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

NickFriend · Post by **NickFriend** » Mon Oct 08, 2018 8:30 am

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

Fabrice · Post by **Fabrice** » Mon Oct 08, 2018 9:20 am

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 ?

ArneOrtlinghaus · Post by **ArneOrtlinghaus** » Mon Oct 08, 2018 9:27 am

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

MathiasHakansson · Post by **MathiasHakansson** » Mon Oct 08, 2018 9:27 am

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.

Fabrice · Post by **Fabrice** » Mon Oct 08, 2018 9:56 am

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

NickFriend · Post by **NickFriend** » Mon Oct 08, 2018 12:03 pm

Great Fab, thanks very much.

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

Nick

ArneOrtlinghaus · Post by **ArneOrtlinghaus** » Mon Oct 08, 2018 1:50 pm

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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