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Re: [virt-tools-list] [PATCH libosinfo 1/3] Fill out media for all Ubuntu distros



On Thu, Feb 23, 2012 at 01:44:35AM +0200, Zeeshan Ali (Khattak) wrote:
> On Thu, Feb 23, 2012 at 1:25 AM, Daniel P. Berrange <berrange redhat com> wrote:
> > On Thu, Feb 23, 2012 at 12:44:15AM +0200, Zeeshan Ali (Khattak) wrote:
> >> On Tue, Feb 21, 2012 at 7:46 PM, Daniel P. Berrange <berrange redhat com> wrote:
> >> > From: "Daniel P. Berrange" <berrange redhat com>
> >>
> >> I really should have paid more attention before ACKing some of the
> >> patches. :) Here is the problem introduced by this one:
> >>
> >> > ---
> >> >  data/oses/ubuntu.xml |  731 ++++++++++++++++++++++++++++++++++++++++++++++++--
> >> >  1 files changed, 711 insertions(+), 20 deletions(-)
> >> >
> >> > diff --git a/data/oses/ubuntu.xml b/data/oses/ubuntu.xml
> >> > index 78239f6..fb331a3 100644
> >> > --- a/data/oses/ubuntu.xml
> >> > +++ b/data/oses/ubuntu.xml
> >> > @@ -6,6 +6,35 @@
> >> >     <version>4.10</version>
> >> >     <vendor>Canonical</vendor>
> >> >     <family>Linux</family>
> >> > +
> >> > +    <media arch="i386">
> >> > +      <url>http://old-releases.ubuntu.com/releases/warty/warty-release-install-i386.iso</url>
> >> > +      <iso>
> >> > +        <volume-id>Ubuntu 4.10 i386</volume-id>
> >> > +        <system-id>LINUX</system-id>
> >> > +      </iso>
> >> > +      <kernel>casper/vmlinuz</kernel>
> >> > +      <initrd>casper/initrd.img</initrd>
> >> > +    </media>
> >> ..
> >> > +
> >> > +    <media arch="i386" live="true" installer="false">
> >> > +      <url>http://old-releases.ubuntu.com/releases/warty/warty-release-live-i386.iso</url>
> >> > +      <iso>
> >> > +        <volume-id>Ubuntu 4.10 i386</volume-id>
> >> > +        <system-id>LINUX</system-id>
> >> > +      </iso>
> >> > +      <kernel>casper/vmlinuz</kernel>
> >> > +      <initrd>casper/initrd.img</initrd>
> >> > +    </media>
> >>
> >> With volume and system ID being identical for both medias, only the
> >> first media will be matched against both types of medias. Same goes
> >> for other medias you added in this patch. Wonder what could be a
> >> solution here though. Perhaps detection code should check if there is
> >> multiple matches and it there are, match basename of known URL against
> >> that of media's patch?
> >
> > Yep, the name is about the only difference between them - all the ISO
> > metadata is identical. The other thing I considered is to add an MD5
> > checksum of the ISO file, which would trivially distinguish them,
> > but I fear that would make it too unique.
> 
> That might be a very good idea actually (Christophe was meaning to do
> that any ways?) but calculation of md5 takes a very long time:
> 
> $ time md5sum ~/ISOs/Fedora-16-x86_64-DVD.iso
> bb38ea1fe4b2fc69e7a6e15cf1c69c91  /home/zeenix/ISOs/Fedora-16-x86_64-DVD.iso
> 
> real	0m23.348s
> user	0m9.276s
> sys	0m1.654s
> 
> so I'll recommend to restrict it to first N bytes, where we could
> think/discuss the value of N but 1MiB should be good enough and takes
> very little time:
> 
> $ time dd if=~/ISOs/Fedora-16-x86_64-DVD.iso bs=1M count=1 2> /dev/null |md5sum
> e25ea147176f24239d38a46f501bd25e  -
> 
> real	0m0.011s
> user	0m0.004s
> sys	0m0.008s
> 
> Actually if we start using md5sum for detection, we can pretty much
> remove all other detection logic/extraction.

Actually I really wouldn't want to remove the other logic - I think
that a checksum could well be too strict, eliminating matches that
should otherwise be allowed. I'd prefer just to use it to resolve
ambiguity when we have multiple matches. A 1 MB checksum would very
likely be sufficient here.

I think we should also have a full checksum in the database to, so
that if an app downloads a remote ISO based on an osinfo URL, it can
verify the download is correct

Some remote download sites actually provide checksum files, so it
might be desirable to have either

   <checksum url="http:/...."/>
   <checksum value="XXXXXXXXXXXXXX"/>

And once we do this kind of thing, we might also consider having a
GPG signature URL too, for sites that publish those.

Regards,
Daniel
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