Current implementation of bootloader processing does not work well with symlinks

[bstaletic]

This is a followup of #41 .

Briefly, with the following LILO configuration (all bootloaders are affected, but I only have LILO installed):

image=/boot/vmlinuz
        label=default
        read-write
        root=/dev/sda1
        append="net.ifnames=0 init=/sbin/openrc-init sysrq_always_enabled=1"
image=/boot/vmlinuz.old
        label=old
        read-write
        root=/dev/sda1
        append="net.ifnames=0 init=/sbin/openrc-init sysrq_always_enabled=1"

and these files in /boot:

-rw-r--r-- 1 root root     512 Jan  3  2022 boot.0800
lrwxrwxrwx 1 root root      18 Aug 13 11:49 config -> config-6.4.10-test
-rw-r--r-- 1 root root  109325 Aug 13 11:49 config-6.4.10-test
-rw-r--r-- 1 root root  109229 Aug  4 08:24 config-6.4.8-test
-rw-r--r-- 1 root root  109324 Aug 10 16:45 config-6.4.9-test
lrwxrwxrwx 1 root root      17 Aug 10 16:45 config.old -> config-6.4.9-test
-rw-r--r-- 1 root root       0 Jan  2  2022 .keep
-rw------- 1 root root   23040 Aug 13 11:49 map
lrwxrwxrwx 1 root root      22 Aug 13 11:49 System.map -> System.map-6.4.10-test
-rw-r--r-- 1 root root 4288104 Aug 13 11:49 System.map-6.4.10-test
-rw-r--r-- 1 root root 4286603 Aug  4 08:24 System.map-6.4.8-test
-rw-r--r-- 1 root root 4287870 Aug 10 16:45 System.map-6.4.9-test
lrwxrwxrwx 1 root root      21 Aug 10 16:45 System.map.old -> System.map-6.4.9-test
lrwxrwxrwx 1 root root      19 Aug 13 11:49 vmlinuz -> vmlinuz-6.4.10-test
-rw-r--r-- 1 root root 7913168 Aug 13 11:49 vmlinuz-6.4.10-test
-rw-r--r-- 1 root root 7909136 Aug  4 08:24 vmlinuz-6.4.8-test
-rw-r--r-- 1 root root 7911952 Aug 10 16:45 vmlinuz-6.4.9-test
lrwxrwxrwx 1 root root      18 Aug 10 16:45 vmlinuz.old -> vmlinuz-6.4.9-test

then running eclean-kernel -a, the expectation is that only the following files would be deleted (everything else is used by the bootloader):

-rw-r--r-- 1 root root  109229 Aug  4 08:24 config-6.4.8-test
-rw-r--r-- 1 root root 4286603 Aug  4 08:24 System.map-6.4.8-test
-rw-r--r-- 1 root root 7909136 Aug  4 08:24 vmlinuz-6.4.8-test

Instead, the regex substitution here fails and only the currently running kernel is preserved, which means at least one more kernel is deleted.

[bstaletic]

Here's my new attempt at fixing this:

https://github.com/bstaletic/eclean-kernel/commit/7b5aeeaa5a22bc357a660eae7ea77f011592d111

If that is a valid approach, I can write a test and make another pull request.

[mgorny]

Yes, the idea looks good. I'm going to have some minor comments but please open the PR. Thank you a lot!

[mgorny]

Fixed in 58ee54e9988aba2a2b4a757faeae39f1d167b1e3.