appState: add PPid tracking for shutting down daemons

[vaxerski]

This won't work on BSD in the current state. @tagattie, can we get PPid + name of any PID on BSDs?

In the future, I'd prefer to use a cgroup within Hyprland, then use that in shutdown, but IIRC BSD doesn't have that. What's the situation look like over there?

[tagattie]

Hi @vaxerski,

This won't work on BSD in the current state. @tagattie, can we get PPid + name of any PID on BSDs?

FreeBSD has sysctl(3) function which can be used for this purpose. Using the function, we can list all processes and search for ones whose parent is Hyprland.

In the future, I'd prefer to use a cgroup within Hyprland, then use that in shutdown, but IIRC BSD doesn't have that. What's the situation look like over there?

I'm not very familiar with cgroup. Is that a mechanism for limiting resources usable by a process? If so, FreeBSD has a command rctl for limitng CPU and memory resources for a process.

[vaxerski]

cgroups can limit resources but here we'd use them to group processes. Once Hyprland would make a cgroup (let's say hyprland-1) then all spawned children would belong under hyprland-1, giving us a way to track descendants even if they double-fork.

[tagattie]

As far as I know, BSDs don't have a similar mechanism. So BSDs would have to list up all processes and check one by one if one's parent (or grandparent, ...) is Hyprland.

[vaxerski]

does it persist through double-forks? Thats the problem on linux at least, if a process forks twice and the first fork exits, PPid is set to 1.

[tagattie]

I'm afraid not. PPid is set to 1 too on BSDs.

I did some research on this topic about BSDs. I have found FreeBSD has procctl(2) which enables a "reaper" process can manage life/death of all its decendants regardless of their generations (child, grandchild, ...) even when mid-level process is killed. However, it is a FreeBSD-specific feature and no other BSDs have similar function.

So generally speaking BSDs provide no reliable mechanism for PPid tracking in that scenario.

[vaxerski]

hey @tagattie I've added BSD code for name, ppid and listing processes. This could use a review / test, as I can't verify the code working on any BSD. Also please check the mibs if you can because I know jbeich added that #if defined(__NetBSD__) || defined(__OpenBSD__) to ppid (that's copied from hyprland) but I did not add it to getting all pids, as the online example didnt have it. Is it required?