On Tue, Feb 07, 2012 at 10:04:04PM +0000, Neil Williams wrote: > On Tue, 07 Feb 2012 19:11:16 +0100 > Michael Biebl <bi...@debian.org> wrote: > > > On 07.02.2012 18:07, Joey Hess wrote: > > > Neil Williams wrote: > > >> I'd like to ask for some help with a bug which is tripping up my tests > > >> with the multiarch-aware dpkg from experimental - #647522 - > > >> non-deterministic behaviour of gzip -9n. > > > > > > pristine-tar hat tricks[1] aside, none of gzip, bzip2, xz are required > > > to always produce the same compressed file for a given input file, and I > > > can tell you from experience that there is a wide amount of variation. If > > > multiarch requires this, then its design is at worst broken, and at > > > best, there will be a lot of coordination pain every time there is a > > > new/different version of any of these that happens to compress slightly > > > differently. > > Exactly. I'm not convinced that this is fixable at the gzip level, nor > is it likely to be fixable by the trauma of changing from gzip to > something else. That would be pointless. > > What matters, to me, is that package installations do not fail > somewhere down the dependency chain in ways which are difficult to fix. > Compression is used to save space, not to provide unique identification > of file contents. As it is now clear that the compression is getting in > the way of dealing with files which are (in terms of their actual > *usable* content) identical, then the compression needs to be taken out > of the comparison operation. Where the checksum matches that's all well > and good (problems with md5sum collisions aside), where it does not > match then dpkg cannot deem that the files conflict without creating a > checksum based on the decompressed content of the two files. [...]
But it's worse than this: even if dpkg decompresses before comparing, debsums won't (and mustn't, for backward compatibility). So it's potentially necessary to fix up the md5sums file for a package installed for multiple architectures, if it contains a file that was compressed differently. Ben. -- Ben Hutchings We get into the habit of living before acquiring the habit of thinking. - Albert Camus -- To UNSUBSCRIBE, email to debian-dpkg-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20120207224923.gc12...@decadent.org.uk