base-files: vkpurge: fix parameter expansion in list_kernels()

[ghost]

This fixes next-kernels from having too much string of their versions
stripped.

Next-kernel versions have the format "vmlinu[xz]--next-".
Thus, the string was wrongly shortened to "", instead of the
correct "-next-".

[ericonr]

You need to change the version or revision or the template in order to get it rebuilt.

[ghost]

Oh, right! Forgot.

[ahesford]

The vkpurge script exists to remove files orphaned by official Void kernel packages. What Void kernel ships with names of the form vmlinu[xz]--next-?

Correct functionality requires that kernel names take the form /boot/vmlinu[xz]-$(uname -r) and that uname -r also have the same form as ${k##*-}. In practice, Void only ships kernels where $(uname -r) does not contain hyphens, so vkpurge works as expected in its current form. If Void were ever to ship kernels with a LOCALVERSION that contained a hyphenated suffix, your change would probably be sufficient to handle those kernels. If Void were to differentiate kernels based on some prefix that does not get incorporated into kernel versioning (for example, vmlinuz-lts-5.7.15_1 for $(uname -r) = 5.7.15_1, the entire vkpurge behavior would need to be rethought.

[q66]

there are no next-kernels in void, so what do you mean?

[ahesford]

I think this is more consistent even if official Void kernels don't ship with anything more than a single hyphen. Let's say a local package (or unpackaged kernel build) modifies LOCALVERSION to be -test_${revision}. We have two kernels:

/boot/vmlinuz-5.7.14_1
/boot/vmlinuz-5.7.14-test_1

Running vkpurge list before this patch is applied, if you are on 5.7.14_1, will show

test_1

and attempting to vkpurge rm all will look for /boot/vmlinuz-test_1, which is clearly not correct.

After the patch, vkpurge list will show

5.7.14-test_1

and vkpurge rm all will look for and successfully delete /boot/vmlinuz-5.7.14-test_1.

[ghost]

The problem I found was that vkpurge listed my kernel with the -next- part stripped, and that string couldn't be used to remove the kernel with vkpurge. In the script I saw that the files are matched against "vmlinu[xz]-*", with no mention of any other hyphens. So ${k##*-} seemed problematic, because it might expand to further hyphens that we don't know of. It simply seemed like an oversight to me. Void doesn't currently prefix any kernels with anything, so this change doesn't affect "official" kernels, but it expands to manually installed kernels. Or is that not right?

[ahesford]

Merging because this should have no change in behavior for current official Void kernels but, if anybody customizes the kernel LOCALVERSION, this should provide more consistent behavior. This almost certainly will not work with your strange "-next-" kernel because I doubt that uname -r returns "-next-". If that "-next-" kernel does not belong to any installed kernel package, this new vkpurge will want to remove the kernel even if it is the currently running kernel.

[ghost]

Thanks!