Cygwin support for large files

Cygwin support for large files

[Rocco Scappatura]

Hello,

I'm using cygwin. I'm using SSH service to connect to the cygwin machine
and to do some shell activities. When I've tried to zip some files on
this machine I get:

$ zip -r "E:/tmp-backup/wslogdb_12102009_042901_log.zip" "G:/Backup/"
  adding: Backup/ (stored 0%)
  adding: Backup/master_db_200910112345.BAK (deflated 95%)
  adding: Backup/model_db_200910112345.BAK (deflated 95%)
  adding: Backup/msdb_db_200910112345.BAK (deflated 88%)
  adding: Backup/Northwind_db_200910112345.BAK (deflated 81%)
  adding: Backup/pubs_db_200910112345.BAK (deflated 90%)
  adding: Backup/WSlogs_1_db_200910112346.BAK
zip error: Entry too big to split, read, or write (file exceeds Zip's
4GB uncompressed size limit)

I fear that it is the kernel (cygwin engine) that can't manage file
greater than 4GB.

Is there any way to workaround this limitation?

Thanks,

rocsca

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Re: Cygwin support for large files

[Markus Hoenicka]

Quoting Rocco Scappatura <Rocco.Scappatura@infracom.it>:

> I fear that it is the kernel (cygwin engine) that can't manage file
> greater than 4GB.
>

http://en.wikipedia.org/wiki/ZIP_file_format#Technical_information

The above entry would rather suggest it is a limitation of zip itself.

regards,
Markus


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Markus Hoenicka
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Re: Cygwin support for large files

[Charles Wilson]

Rocco Scappatura wrote:
> I fear that it is the kernel (cygwin engine) that can't manage file
> greater than 4GB.

Cygwin has supported large files since version 1.5.0 (although depending
on context, applications themselves might make unwarranted assumptions
that break large file support, like assuming that file size or offset
fits into a 'long').

> Is there any way to workaround this limitation?

The limitation is in the version of ZIP provided in the cygwin-1.5
distrbution.  ZIP64 support was added in zip-3.0:

> Zip64 support.  This version supports Zip64 archives as described in the
> PKWare AppNote.  These archives use additional fields to support archives
> greater than 2 GB and files in archives over the 2 GB previous limit (4 GB
> on some ports).  The Zip64 format also allows more than 64k entries in an
> archive.  Support by the OS for files larger than 4 GB is needed for Zip to
> create and read large files and archives.  On Unix, Win32, and some other
> ports, large file and Zip64 support is automatically checked for and
> compiled in if available.  Use of Zip64 by Zip is automatic and to maximize
> backward compatibility the Zip64 fields will only be used if needed.  A
> Zip64 archive requires a pkzip 4.5 compatible unzip, such as UnZip 6.0.

What version of ZIP is being used on your remote cygwin machine?

--
Chuck

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Re: Cygwin support for large files

[Charles Wilson]

Charles Wilson wrote:
> The limitation is in the version of ZIP provided in the cygwin-1.5
                ^^^^
               may be
> distrbution.  ZIP64 support was added in zip-3.0:

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RE: Cygwin support for large files

[Rocco Scappatura]

Thanks Markus,
 
> > I fear that it is the kernel (cygwin engine) that can't manage file
> > greater than 4GB.
> >
> 
> http://en.wikipedia.org/wiki/ZIP_file_format#Technical_information
> 
> The above entry would rather suggest it is a limitation of zip itself.

I know that this is no the right place where to ask for a solution to
the large files limitation, but have you any idea of how to setup my
cygwin environment so that I can zip also files greater than 4GB?

Thanks,

rocsca

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RE: Cygwin support for large files

[Rocco Scappatura]

Hello,

> > The limitation is in the version of ZIP provided in the cygwin-1.5
>                 ^^^^
>                may be
> > distrbution.  ZIP64 support was added in zip-3.0:

I sit possible to get from somewhere zip-3.0 for cygwin?

rocsca 

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Re: Cygwin support for large files

[Charles Wilson]

Rocco Scappatura wrote:
>>> The limitation is in the version of ZIP provided in the cygwin-1.5
>>                 ^^^^
>>                may be
>>> distrbution.  ZIP64 support was added in zip-3.0:
> 
> I sit possible to get from somewhere zip-3.0 for cygwin?

Using setup, install the current version. For cygwin-1.5, that is
zip-3.0-2 (the previous version, which you may still be using, was
2.32-2 and did not support ZIP64).  For cygwin-1.7, the current version
is zip-3.0-11 (no version of zip earlier than 3.0 has ever been
available for cygwin-1.7).

We wouldn't need to go through this if you had followed the
recommendations here:

http://cygwin.com/problems.html

on reporting problems. Please *attach* (do not paste) the output of
'cygcheck -s -v -r' to your next email.

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RE: Cygwin support for large files

[Rocco Scappatura]

Thanks Charles,

> Rocco Scappatura wrote:
> >>> The limitation is in the version of ZIP provided in the cygwin-1.5
> >>                 ^^^^
> >>                may be
> >>> distrbution.  ZIP64 support was added in zip-3.0:
> >
> > I sit possible to get from somewhere zip-3.0 for cygwin?
> 
> Using setup, install the current version. For cygwin-1.5, that is
> zip-3.0-2 (the previous version, which you may still be using, was
> 2.32-2 and did not support ZIP64).  For cygwin-1.7, the current
version
> is zip-3.0-11 (no version of zip earlier than 3.0 has ever been
> available for cygwin-1.7).
> 
> We wouldn't need to go through this if you had followed the
> recommendations here:
> 
> http://cygwin.com/problems.html
> 
> on reporting problems. Please *attach* (do not paste) the output of
> 'cygcheck -s -v -r' to your next email.

I've updated zip and (I hope that) everything works!

rocsca

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RE: Cygwin support for large files

[Rocco Scappatura]

Hi again!

> > >>> The limitation is in the version of ZIP provided in the cygwin-
> 1.5
> > >>                 ^^^^
> > >>                may be
> > >>> distrbution.  ZIP64 support was added in zip-3.0:
> > >
> > > I sit possible to get from somewhere zip-3.0 for cygwin?
> >
> > Using setup, install the current version. For cygwin-1.5, that is
> > zip-3.0-2 (the previous version, which you may still be using, was
> > 2.32-2 and did not support ZIP64).  For cygwin-1.7, the current
> version
> > is zip-3.0-11 (no version of zip earlier than 3.0 has ever been
> > available for cygwin-1.7).
> >
> > We wouldn't need to go through this if you had followed the
> > recommendations here:
> >
> > http://cygwin.com/problems.html
> >
> > on reporting problems. Please *attach* (do not paste) the output of
> > 'cygcheck -s -v -r' to your next email.
> 
> I've updated zip and (I hope that) everything works!

I confirm that it works! Still thanks everyone,

rocsca

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