[delphizip] Re: New format - a suggested name
- From: "Russell Peters" <russellpeters@xxxxxxxxxxx>
- To: <delphizip@xxxxxxxxxxxxx>
- Date: Sun, 3 Nov 2002 08:40:11 +1100
I think you will find that the problem with 4k+ files lies in the VCL
routines (memos + directory list) and are Delphi version dependant. Given
sufficient memory the dlls should not have trouble with the number of files
and certainly the zip format format does not care but restricts file sizes
to 32 bits.
There can be problems with sending large numbers of filespecs to the dlls
(each one ends up with 4 copies).
More information about the file/ operating system can be stored in the
'extra field' but this is application specific.
A good source for information formats is
http://www.pkware.com/support/appnote.html
This gives there proposed Zip64 format (which they admit is a kludge) but
also gives details of some present uses of the extra data.
Unless you make the name field fixed to a very generous size (4096 windows)
renaming of files will always entail rewriting the zip file but how often do
you rename a file!
Russell Peters
http://www.users.bigpond.com/russellpeters/delphizip.html
p.s. new name - you could shorten the extension to .zp (after all it is
supposed to be compressed)
----- Original Message -----
From: "Alistair George" <bigal@xxxxxxxxxx>
To: <delphizip@xxxxxxxxxxxxx>
Sent: Sunday, November 03, 2002 6:02 AM
Subject: [delphizip] Re: New format - a suggested name
>
> Hello All,
> We had the QIC format and various other formats through the years (this is
> relating to backup software of course). Now QIC is redundant with
Microsoft XP,
> why, there is no explicable reason which makes older backups inaccessible
in that
> O/S. Some of the other formats are excellent BUT
> ZIP remains the most popular and, IMHO if _at all possible_ it should be
> retained and kept compliant with INFOzip standard. So, if headers are
modified
> as gslrunk/Gerard cleverly suggests earlier, the file remains compatible.
>
> There are other standards which compress better, but who really cares with
> increased disk space these days and use of CDR/RW media for transportation
this
> is not an issue usually.
>
> For the selfish reason I am developing backup software _the most
disconcerting_
> issues at present with DelphiZIP (and for that matter other zip) is that:
> a) they have potential problems with file counts over 4k
> b) the zipdll will not handle empty directories eg c:\jobs has no files,
but has
> several directories within containing files. If c:\jobs\*.* is sent to the
DLL
> it wont zip the contents.
>
> Unlikely but; I was wondering if 'disk spanning' is used whether the
4k file
> count is still an issue. Also if disk spanning is used that its Achilles
heel
> in that to get the directory on any disk other than the last requires the
last.
> Perhaps this might be worked through on the header info pointing to a
current
> directory file appended in the current disk also???
>
> Cheers,
> Al+
>
>
> Sunday, November 3, 2002, 5:19:21 AM, you wrote:
>
> JT> Has anyone used the file extension or name Z++?
>
> JT> If, as a group we decide to create a new format, or if an individual
chooses
> JT> to create a new format, it must have a name.
>
> JT> James Turner
>
>
>
>
>
> --
> Regards,
> Alistair+
>
>
>
Other related posts:
