[Bug 1934992] Re: rsync 3.2.x in Groovy depends on broken libxxhash 0.7.x

Fri Jul 9 12:02:31 UTC 2021

Hello Walter,

Thanks for filling the bug and helping in making the Ubuntu server
better.

However, if I get everything right, I think you're mistaken about how it
works and I am sorry but what you're trying to do is not correct! You
cannot just decide to take one of the package from another release and
the other from another release. That is not how it works, I am afraid :/

If you do a fresh installation of rsync on Groovy, everything works
fine! See here:

$ lxc launch images:ubuntu/groovy groovy-rsync
$ lxc shell groovy-rsync
# apt update && apt install rsync
  ### here you'll see that the right version of libxxhash gets installed.
      (cf: `Setting up libxxhash0:amd64 (0.8.0-1ubuntu1.20.10.1) ...)
# ls -lah /usr/lib/x86_64-linux-gnu/libxxhash.so.0
lrwxrwxrwx 1 root root 18 Jan 12 11:17 /usr/lib/x86_64-linux-gnu/libxxhash.so.0 -> libxxhash.so.0.8.0

...which is linked against the right version. Further libxxhash-
dev/0.8.0-1 is not in Focal but in Groovy, so the patch will not be
right to apply in Focal. That said, I agree that it'd have been nice to
have that version constraints but I don't see this as something that'd
cause problems unless somebody tries to do some sort of manual
intervention. :)

Given this, I am inclined towards believing that this is not really a
bug in rsync but a "local" issue (that is, manually installing a version
of rsync from Groovy to Focal and expecting it to work w/ libxxhash-
dev). So I am setting this to "Incomplete" for now, leaving some space
for discussion - in case I wrongly interpreted your problem and thus
this report.

But should you feel that it's still a bug, please set the status back to
"New" along with some reasoning (and hopefully a reproducer!) as to why
you think that it's indeed a bug rather than a local issue. Thank you,
again! \o/

** Changed in: rsync (Ubuntu)
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1934992

Title:
  rsync 3.2.x in Groovy depends on broken libxxhash 0.7.x

Status in rsync package in Ubuntu:
  Incomplete

Bug description:
  **Problem**

    $ rsync root at focal-system:/etc/.pwd.lock . 
    ERROR: .pwd.lock failed verification -- update discarded.
    rsync error: some files/attrs were not transferred (see previous errors)
      (code 23) at main.c(1816) [generator=3.2.3]

    $ rsync root at focal-system:/etc/.pwd.lock . --debug=all
    opening connection using: ssh -l root focal-system rsync --server --sender \
      -e.LsfxCIvu . /etc/.pwd.lock  (10 args)
    (Client) Protocol versions: remote=31, negotiated=31
    Client negotiated checksum: xxh128
    ...

  **Cause**

    focal-system# dpkg -l | grep -E 'libxxhash|rsync'
    ii  libxxhash0:amd64  0.7.3-1         amd64
    ii  rsync             3.2.3-2ubuntu1  amd64

  **Why this affects only us and not more people?**

  On Ubuntu/Focal, there is no rsync 3.2.3, only 3.1.3-8. But because we
  need the lz4 compression support we've fetched a newer rsync (from
  Groovy).

  However: the rsync 3.2.3 depends on libxxhash0 0.7.1+, while in fact
  it needs 0.8+.

  **Details**

  On a Ubuntu/Focal system we have installed a rsync 3.2.3 package from Ubuntu/Groovy because we need the lz4 compression support.

  focal-system# apt-cache show rsync
  Package: rsync
  ...
  Version: 3.2.3-2ubuntu1
  Depends: lsb-base, libacl1 (>= 2.2.23), libc6 (>= 2.15),
    liblz4-1 (>= 0.0~r130), libpopt0 (>= 1.14), libssl1.1 (>= 1.1.0),
    libxxhash0 (>= 0.7.1), libzstd1 (>= 1.3.8), zlib1g (>= 1:1.1.4)
  ...

  Alongside this we had libxxhash0 0.7.3-1 from Focal:

  focal-system# apt-cache policy libxxhash0
  libxxhash0:
    Installed: 0.7.3-1
    Candidate: 0.7.3-1
    Version table:
   *** 0.7.3-1 500
          500 http://ARCHIVE/ubuntu focal/universe amd64 Packages
          100 /var/lib/dpkg/status

  According to the dependencies, this should work. But the combination does not, as this quote from the rsync maintainer would tell you:
  https://github.com/WayneD/rsync/issues/122#issuecomment-737690913
  > Yeah, Cyan4973 could have told you that the 128-bit xxhash only
  > just stabilized in its 0.8.0 release, so anything older than
  > that isn't compatible.

  **The fix**

  As the maintainer points out, version 0.7 is not stable (= broken for
  our intents and purposes) and thus not fit for use with rsync 3.2.

  I would argue that it's a good idea to bump the dependency of rsync
  3.2.3 on Groovy to libxxhash0>=0.8

  After all, in Groovy there is a libxxhash0 0.8.0-1ubuntu1.20.10.1, so
  that would not be a problem. And it would fix issues for those mixing
  and matching packages.

  Thanks!

  Walter Doekes
  OSSO B.V.

  (*) possible patch:

  $ diff -pu debian/control{.orig,}
  --- debian/control.orig	2021-07-08 09:56:57.646861644 +0200
  +++ debian/control	2021-07-08 09:57:38.499029903 +0200
  @@ -8,7 +8,7 @@ Build-Depends: debhelper-compat (= 13),
                  libacl1-dev,
                  libpopt-dev,
                  liblz4-dev,
  -               libxxhash-dev,
  +               libxxhash-dev (>= 0.8),
                  libzstd-dev,
                  zlib1g-dev,
                  libssl-dev

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