Date: Mon, 08 Jul 2002 15:58:36 -0700 From: Wes Peters <wes@softweyr.com> To: Doug Barton <DougB@FreeBSD.org> Cc: Dag-Erling Smorgrav <des@ofug.org>, Dan Moschuk <dan@FreeBSD.org>, arch@FreeBSD.org Subject: Re: Package system flaws? Message-ID: <3D2A191C.3103D0FB@softweyr.com> References: <20020707152651.V679-100000@master.gorean.org>
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Doug Barton wrote:
>
> On Sun, 7 Jul 2002, Terry Lambert wrote:
>
> > > We want to be able to install a package from a non-rewindable source
> > > without storing a temporary copy on disk. This means the metadata
> > > must without fail be at the very beginning of the package.
>
> Ok, then what about storing the meta data as a seperate file? Why do they
> have to be in the same package?
So you can (md5, sign) them together and know that they "apply" to each
other.
If you're sensible about the encoding, the metadata doesn't have to be
at the beginning of the media. Consider a simple package that has
a collection of binaries and two language sets; you have to install
one or both language sets.
You put the binaries in first, because everyone has to install those.
Then you put one of the language sets, then the other. In the encoding,
you specify the size of the fileset blob following, so if I'm going to
skip the first set and install the second, I know how many bytes to
skip over. On a tape or disk, you can seek forward this many bytes,
on a socket stream you have to just read and skip that many bytes.
If you're just looking at the package gleaning metadata, you skip over
all 3 blobs; pkg_info would do this. The actual encoding of the blobs
is inconsequential, you could use 3 different encodings to get the
maximum compression on each if you wished -- as long as pkg_add supports
all of those encodings. The logical firsts are PROBABLY tar (or cpio)
and gzip/bzip2. Features of the encoding format like headers don't
matter since we're not going to put the metadata into the encodings.
--
"Where am I, and what am I doing in this handbasket?"
Wes Peters Softweyr LLC
wes@softweyr.com http://softweyr.com/
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