On Sun, 2 Apr 2017 20:56:31 -0700 Pádraig Brady <p...@draigbrady.com> wrote:
> On 02/04/17 08:51, Matias Fonzo wrote: > > Hello Pádraig, > > > > On Mon, 27 Mar 2017 20:28:35 -0700 > > Pádraig Brady <p...@draigbrady.com> wrote: > > > >> On 27/03/17 19:55, Michael Stone wrote: > >>> On Mon, Mar 27, 2017 at 11:47:10PM +0100, Ariel Santana Naranjo > >>> wrote: > >>>> If changing xz's options can't fix the problem, would you re-add > >>>> a second format? Until coreutils-8.13 the tarball was > >>>> distributed in two formats. I think adding a second format > >>>> would fix the problem for busybox and for pristine-tar because > >>>> xz seems to be the only format affected by these problems! > >>> > >>> What, exactly, is the problem? > >> > >> busybox's unxz can't detect bit errors during uncompression > >> due to not supporting the default crc64 checksum generated by xz. > >> It could if you generate the tarball with xz --check=crc32. > >> Though I don't think it's practical to adjust all projects > >> to pass this option to xz; rather adding crc64 support to > >> unxz seems like the best approach. > >> > >> Note if you're extracting the tarball then you're not on a > >> deeply embedded device without a compiler etc. so it would > >> be surprising that xz would not be available. > > > > Err, busybox supplies xz... > > Sure. But my point was if you're compiling on this system, > a crc64 capable xz shouldn't be too hard to obtain. > > >> Even in that extreme edge case, you could use an intermediate > >> system to extract and checksum the data. > > > > What if this intermediate system is not available?. > > See point above. > Anyway the general point of this thread is that > fixing this with options to each generator of xz is not practical. > Either the default xz crc should be changed to crc32, > or more likely busybox xz would gain crc64 support. All of what you propose are patches to palliate part of the symptoms of the bad design of xz. And in addition -- to be implemented by others. The use of a format that does not have these problems is not mentioned here!
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