Description of problem: Using applydeltaiso to go from Fedora-15RC1 to Fedora-15RC2 fails.
Version-Release number of selected component (if applicable):
How reproducible: every time
Steps to Reproduce:
1. applydeltaiso Fedora-15RC1-i386-DVD.iso Fedora-15-Final.RC1_RC2-i386-DVD.diso foo >foo.stdout 2>foo.stderr
2. echo $?; cat foo.stderr
1 ## failure
md5sum mismatch, iso is corrupt
Expected results: success
$ ls -l foo Fed*
-rw-rw-r--. 1 3650618108 May 13 08:05 foo
-rw-rw-r--. 1 204913954 May 12 19:41 Fedora-15-Final.RC1_RC2-i386-DVD.diso
-rw-rw-r--. 1 148 May 13 08:13 Fedora-15-Final.RC1_RC2-i386-MD5SUM
-rw-rw-r--. 1 3666591744 May 11 14:53 Fedora-15RC1-i386-DVD.iso
-rw-rw-r--. 1 3650484224 May 13 07:56 Fedora-15RC2-i386-DVD.iso
$ sha256sum foo Fedora-15RC1-i386-DVD.iso Fedora-15RC2-i386-DVD.iso
$ sed 1q < Fedora-15RC1-i386-CHECKSUM ## matches RC1
$ sed 1q < Fedora-15RC2-i386-CHECKSUM ## matches RC2, but mismatches 'foo'
$ sed 1q < Fedora-15-Final.RC1_RC2-i386-MD5SUM
$ md5sum Fedora-15-Final.RC1_RC2-i386-DVD.diso ## matches
$ rpm -qf /usr/bin/applydeltaiso
$ rpm --verify deltaiso; echo $?
$ grep -v unchanged foo.stdout
reading 329057840 bytes from old iso...done
dconf.i686 (xz.2): applying delta
dracut.noarch (xz.2): applying delta
dracut-caps.noarch (xz.2): applying delta
dracut-fips.noarch (xz.2): applying delta
dracut-network.noarch (xz.2): applying delta
dracut-tools.noarch (xz.2): applying delta
fedora-release-notes.noarch (xz.2): applying delta
Works with deltaiso-3.6-0.6.20110223git.fc15.x86_64
The problem is that deltarpm in F14 is linked against xz-4.999.9, while in F15 it's linked against xz-5.0.1. In the switchover from 4.999 to 5.0, xz modified its compression algorithm so that compressed files are (very) slightly different. If you're interested, see http://cedarandthistle.wordpress.com/2011/02/16/brittle-deltas-a-possible-solution for more detail.
So, basically, we're stuck. If you apply a F15 deltaiso using deltaiso from F15, it works (as you've already seen). If you use the F14 one, it won't. One thought Andre Robatino and I were throwing around was to host a F14 copy of deltaiso that was statically linked against xz-5.0.x so you could use it for F15 deltaisos, but then that version of deltaiso will no longer work with F14 deltaisos.
Anyhow, there's no easy way that I can see to fix this. Afraid I'm going to have to close this as CANTFIX. If you can see a workable solution, please reopen.
Please comment on these two possibilities which have slightly different goals.
1) Goal: generate intended output (byte-for-byte identical). Method: add a commandline parameter "--external-xz='<path_and_paramters>'" which lets the user specify a substitute xz and its command-line flags. Then the expert user could use the other xz installed somewhere else, or could specify flags that would cause xz to choose its settings to be compatible with specific .isos.
2) Goal: generate "usable" output: something that will pass MediaCheck and will install correctly, but may be different from the intended .iso because of xz differences. Method: detect non-equality as now, but then recover. Run implantisomd5 on the output so that MediaCheck passes, change the exit code from 1 to 2, change the stderr message to something such as "The output is not byte-for-byte identical with the intended .iso because of differences in xz compression. However, the output .iso is equivalent: the results of an install will be the same, and the .iso also passes MediaCheck."
Choice 2) will require significant work. "implantisomd5 --force" succeeds and the resulting .iso boots, passes MediaCheck, and begins an install. However, most of Packages/*.rpm is garbage; begining with:
error: deja-dup-18.1.1-1.fc15.i686.rpm: not an rpm package (or package manifest)
error: dejavu-fonts-common-2.33-1.fc15.noarch.rpm: not an rpm package (or package manifest)
error: dejavu-lgc-sans-fonts-2.33-1.fc15.noarch.rpm: not an rpm package (or package manifest)
error: dejavu-lgc-sans-mono-fonts-2.33-1.fc15.noarch.rpm: not an rpm package (or package manifest)
as diagnosed by "rpm --verify -p Packages/*.rpm"; 2471 out of 2944 are bad.
This looks like applydeltaiso has shifted the blocks of an ISO9660 filesystem without adjusting the directory entries. Applydeltaiso claims "copying unchanged" for almost every *.rpm (all except the 7 mentioned in original Description above) but it seems that the copy did not go to the correct blocks of the .iso per the ISO9660 directory.
Altogether, it seems to me that applydeltaiso should adopt a more-sceptical attitude. Examine the names of the .rpms, and refuse to proceed when a known bad case is detected (such as this case, with mismatched xz for .fc15 on Fedora 14). Even more, use evidence-based tests: pick the 25th-largest .rpm, uncompress it, re-compress it, and refuse to proceed unless it matches the original.
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