[Libguestfs] [PATCH] v2v: Fix kernel disambiguation by dropping Epoch field (RHBZ#1669395).

[Pino Toscano]

On Tuesday, 29 January 2019 11:41:16 CET Richard W.M. Jones wrote:
> When detecting kernels we have to list the files in the package to
> find the right /boot/vmlinuz file.
> 
> In virt-v2v 1.28 we ran:
> 
>   rpm -ql kernel
> 
> Because multiple kernels can be installed this gave incorrect results,
> which was reported in RHBZ#1161250 and initially fixed in
> commit 377bc302f11db3da4263f894c76a7d280fb25dbd.  This changed the
> command to:
> 
>   rpm -ql [epoch:]kernel-version.release
> 
> where the epoch: prefix was only used if the epoch was != 0.
> 
> However this in fact failed if epoch was != 0 (which isn't the case
> for ordinary RHEL kernels in RHEL >= 5).  Since it broke RHEL <= 4
> this was reported as bug RHBZ#1170685 and fixed only for RHEL 3/4 in
> commit 205a8c7ca1ed1d66bef56d75c3c244e726e3bbbf.
> 
> That fix removed the optional epoch: prefix for RHEL 3/4.  But the
> prefix is wrong on all versions of RPM, even the latest one.  eg. on
> Fedora 29:
> 
>   $ rpm -ql 2:qemu-3.1.0-4.fc30.x86_64
>   package 2:qemu-3.1.0-4.fc30.x86_64 is not installed
> 
> (In fact latest RPM does let you use name-epoch:version.release, but
> that was not true in RHEL 6 or 7).
> 
> The solution here is to remove the epoch entirely.  It's rather
> unlikely that two kernels will be installed with identical NVR and
> different Epoch.  Just using NVR is sufficient to fix the original bug
> RHBZ#1161250.

Or it could do what supermin does, i.e. use NEVR:

  let rpm_package_to_string pkg =
    (* In RPM < 4.11 query commands that use the epoch number in the
     * package name did not work.
     *
     * For example:
     * RHEL 6 (rpm 4.8.0):
     *   $ rpm -q tar-2:1.23-11.el6.x86_64
     *   package tar-2:1.23-11.el6.x86_64 is not installed
     * Fedora 20 (rpm 4.11.2):
     *   $ rpm -q tar-2:1.26-30.fc20.x86_64
     *   tar-1.26-30.fc20.x86_64
     *
     *)
    let is_rpm_lt_4_11 =
      !rpm_major < 4 || (!rpm_major = 4 && !rpm_minor < 11) in
  
    let rpm = rpm_of_pkg pkg in
    if is_rpm_lt_4_11 || rpm.epoch = 0 then
      sprintf "%s-%s-%s.%s" rpm.name rpm.version rpm.release rpm.arch
    else
      sprintf "%s-%d:%s-%s.%s"
        rpm.name rpm.epoch rpm.version rpm.release rpm.arch

https://github.com/libguestfs/supermin/blob/master/src/ph_rpm.ml#L171

I just sent a patch to fix this:
https://www.redhat.com/archives/libguestfs/2019-January/msg00222.html

-- 
Pino Toscano
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