On Wed, Sep 01, 2004 at 10:43:56PM +0200, Richard Atterer wrote: >On Wed, Sep 01, 2004 at 08:31:13PM +0100, Steve McIntyre wrote: >> I've used a new data type (8) in JTE/mkimage to describe >> bzip2-compressed data chunks rather than 2 for gzip. I'm _not_ >> releasing this code just yet (at least until after sarge), but I think >> it will be worth it for the ~15% extra compression for template files. > >That's nice - I admit I just assumed that since the template data is >binary, gzip would do better than bzip2, but never actually checked whether >that is the case... Hey, I wasn't sure myself so I just tried it. :-) >> Please reserve 8 for this use; I'll work on a patch for jigdo-file >> shortly. > >Hmm, I don't think that a new type code is necessary for this. It would >make more sense to add a new type of section, say "BZIP" for bzipped, >leaving "DATA" for gzipped. > >Imagine the (admittedly rather theoretical) case that a .template contains >both gzipped and bzipped data - since each DATA/BZIP section can either be >bzipped OR gzipped, and one such section can hold the data for /several/ >"unmatched data" (type==2) entries, those entries are obviously the wrong >place to make the bzip vs. gzip distinction. Actually, yes. >I just checked whether it would be possible to keep "DATA" for both types >of sections and look at the zlib/bzip2 stream to distinguish them, but this >would probably be difficult: zlib streams (!= .gz files) start with 2 flag >bytes which can have several different values. > >If you can wait for a month or two, I might get around to adding this >myself. The cleanest solution in my eyes is to reorganize zstream.hh and >friends, adding an abstract base class so that zstream objects and >instances of the to-be-written bzstream classes can be used >interchangeably. The resulting C++ might be a bit too hairy for your taste. >:-) Hmmm. :-) I've written a proof of concept using type 8, but I agree that that's the wrong way to do it. Using a new BZIP section would be better. I'll change my code to do that shortly. -- Steve McIntyre, Cambridge, UK. steve@einval.com "Further comment on how I feel about IBM will appear once I've worked out whether they're being malicious or incompetent. Capital letters are forecast." Matthew Garrett, http://www.livejournal.com/users/mjg59/30675.html
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