[delphizip] Re: New spanning scheme - allows SFX
- From: "Russell Peters" <russellpeters@xxxxxxxxxxx>
- To: <delphizip@xxxxxxxxxxxxx>
- Date: Thu, 9 Jan 2003 07:28:23 +1100
I can live with separate files and compatibility.
It was only an idea
- Russell
----- Original Message -----
From: "Roger Aelbrecht" <Roger.Aelbrecht@xxxxxxxxxx>
To: <delphizip@xxxxxxxxxxxxx>
Sent: Thursday, January 09, 2003 4:49 AM
Subject: [delphizip] Re: New spanning scheme - allows SFX
>
> James Turner wrote:
> > The format proposed below would be incompatible with standard methods
> > to assemble zip archives. In a spanned disk set, I can see no
> > advantage, to combining the zip reader code into the zip file. To me,
> > this seems to be unnecessary work producing a format that would not
> > be compatible with existing zip software.
> >
> > As far as I can remember, Winzip uses a separate zip reader program
> > with sfx disk sets.
> >
> > -- James Turner
> >
> >>
> >> From: "Russell Peters" <russellpeters@xxxxxxxxxxx>
> >> Date: 2003/01/08 Wed AM 05:00:24 GMT
> >> To: <delphizip@xxxxxxxxxxxxx>
> >> Subject: [delphizip] New spanning scheme - allows SFX
> >>
> >>
> >> Proposal for new ZipSpan that can SFX
> >>
> >> The main file is the Central Directory or SFX + Central Directory
> >> ie
> >> optional SFX code
> >> Central Directory
> >> End of Central
> >>
> >> must all fit on one disk (the last one)
> >> the part files are a header followed by data
> >> ie
> >> header (consists of, at least, signature + sequence number)
> >> Data
> >>
> >>
> >> Central Directory too big to fit on one disk?
> >> - no problems just compress it as special entry in main file
> >> directory. ('###DIRECTORY.ZIP' ?)
> >> This would be automatically expanded (and used).
> >>
> >> Problems -
> >> If Directory must be compressed, it would need to follow all other
> >> data (so need to load multiple disks to get Directory)
> >> Biggest problem is - if main file won't entirely fit on last disk
> >> (in space not used by last part of data) that space is waisted!
> >> not compatible with anything else though the main file could be
> >> listed with anything
> >> (may only show '###DIRECTORY.ZIP' ?)
> >> Cannot be done with ZipMaster as yet!
> >>
> >> Russell Peters
> >> http://www.users.bigpond.com/russellpeters/delphizip.html
>
> I agree with James.
>
> The format I proposed to Markus uses two separate files
> the SFX stub and a added filelist
> with :
> - number of files
> - for each file : name+ size+ disknbr
> for this the size is calculated + size of sfx is kept free on disk1
> then normal spanning is used then sfx-stub with table added to disk1
>
> This allows standard zip programs to handle the archive as a normal zip
> file. The sfx code does not use the central directory but the file list
and
> the local headers to find the files on the disks, disks are called when
> needed
> and if nobody changes the list they are in a logical order.
> Can send you the code if you want to compare.
> Unfortunately we don't have a working project
>
> Roger Aelbrecht
> http://web.wanadoo.be/driehoeksw
>
>
>
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