Fix %post and %postun generation in kmodtool

[stormi]

During zfs-kmod RPM build, $(uname -r) gets unintentionally evaluated on
the build host, once and for all. It should be evaluated during the
execution of the scriptlets on the installation host. Escaping the $
character avoids evaluating it during build.

Signed-off-by: Samuel Verschelde stormi-xcp@ylix.fr

Motivation and Context

I'm maintaining the zfs packages for XCP-ng, a free virtualization solution forked from XenServer (https://xcp-ng.org/). I noticed that depmod -a was not executed after the module RPM was installed and this led me to discovering this bug in kmodtool as shipped by the project with the source RPMs.

The %post and %postun scriptlets generated by kmodtool are broken: either the build host has the same running kernel as the target kernel and then depmod -a will be executed each time a zfs-kmod-xxx package is installed, or the version is different (as in my example below) and depmod -a is never executed because the test always evaluates to false.

Description

Escape $(uname -r) so that it's not evaluated on the build host.

How Has This Been Tested?

RPM built in a docker container then checked with rpm -qp nameoffile --scripts and installed on an XCP-ng host (centos based with custom kernel). modprobe zfs worked without the need to run depmod -a manually whereas it didn't before the fix on similar hosts.

Output of rpm -qp nameoffile --scripts before the change:

$ rpm -qp kmod-zfs-4.19.0+1-0.8.0-1.xcpng8.0.x86_64.rpm --scripts                                                                 
postinstall scriptlet (using /bin/sh):
[[ "3.10.0-957.12.1.el7.x86_64" == "4.19.0+1"  ]] && /sbin/depmod -a > /dev/null || :
postuninstall scriptlet (using /bin/sh):
[[ "3.10.0-957.12.1.el7.x86_64" == "4.19.0+1"  ]] && /sbin/depmod -a > /dev/null || :

Output after the fix:

$ rpm -qp --scripts RPMS/x86_64/kmod-zfs-4.19.0+1-0.8.0-1.1.xcpng8.0.x86_64.rpm
postinstall scriptlet (using /bin/sh):
[[ "$(uname -r)" == "4.19.0+1"  ]] && /sbin/depmod -a > /dev/null || :
postuninstall scriptlet (using /bin/sh):
[[ "$(uname -r)" == "4.19.0+1"  ]] && /sbin/depmod -a > /dev/null || :

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the ZFS on Linux code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• All commit messages are properly formatted and contain Signed-off-by.

[behlendorf]

Thanks! Looks good, I also verified that this same fix was applied to the upstream kmodtool.

[ofaaland]

LGTM. Thanks!

[codecov]

Codecov Report

Merging #8866 into master will increase coverage by 0.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #8866      +/-   ##
==========================================
+ Coverage   78.65%   78.73%   +0.08%     
==========================================
  Files         382      382              
  Lines      117778   117778              
==========================================
+ Hits        92638    92735      +97     
+ Misses      25140    25043      -97

Flag	Coverage Δ
#kernel	79.32% <ø> (-0.04%)	⬇️
#user	67.46% <ø> (+0.25%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 893a6d6...6ac7c90. Read the comment docs.