Kernel version sort incorrect for RHEL

[mxey]

needrestart sorts RHEL kernel versions incorrectly:

[root@host~]# needrestart -k -b
NEEDRESTART-VER: 2.9
NEEDRESTART-KCUR: 3.10.0-693.1.1.el7.x86_64
NEEDRESTART-KEXP: 3.10.0-693.el7.x86_64
NEEDRESTART-KSTA: 3

That output is from needrestart 2.9, but I have a small test that reproduces the problem on latest Git master:

#!/usr/bin/perl
use v5.14;
use warnings;
use Test::More tests => 1;

use lib 'perl/lib';

use NeedRestart::Kernel;

my @kernels = qw(
    3.10.0-693.1.1.el7.x86_64
    3.10.0-693.el7.x86_64
    3.10.0-514.21.1.el7.x86_64
    3.10.0-327.el7.x86_64
);
my ($version) = reverse sort {nr_kernel_vcmp($a, $b);} @kernels;

is $version, '3.10.0-693.1.1.el7.x86_64';

Output:

1..1
not ok 1
#   Failed test at /…/kernel_sort.t line 18.
#          got: '3.10.0-693.el7.x86_64'
#     expected: '3.10.0-693.1.1.el7.x86_64'
# Looks like you failed 1 test of 1.

[liske]

Is there any documentation available on howto compare RHEL (kernel) versions?

[mxey]

I don't think so, except the implementation of "rpmvercmp” in RPM. I found this Perl module that implements it though: https://metacpan.org/pod/RPM::VersionSort

Similar to Debian epoch, upstream version, Debian revision, RPM has epoch, version and release, which are different fields that probably have to be compared individually. In “3.10.0-693.1.1.el7” the version is 3.10.0 and the release is 693.1.1.el7. The epoch defaults to 0.

[liske]

I've adopted the version handling of RPM::VersionSort which will be used on RHEL environments (there is a line using RPM version sorting in verbose mode). It seems to work with your test.

Thanks for reporting this issue.

[mxey]

I took a quick look at your commit. You only check for /etc/redhat-version, which I see neither on RHEL nor CentOS. I have a /etc/redhat-release though.

The combined check for the absence of dpkg might lead to a false negative, in case somebody has installed dpkg (which you can do, just like the RPM tools are available in Debian)

[liske]

Thanks for looking at the commit.

• /etc/redhat-release - this was a typo, I should have used copy'n'paste ;-)
• dpkg - I did not expect that dpkg can be installed as rpm on Debian. I've replaced the check by testing if /etc/debian_version does not exist.