BIF for more detailed process information

[hauleth]

Is your feature request related to a problem? Please describe.

In systemd integration library it would be useful to have access to process effective user ID and process effective group ID. Unfortunately there is only a way to get process ID (weirdly, it is returned as a string instead of a number).

Describe the solution you'd like

I have created a library that provides such functionality via NIF. It provides simple function os_process:info/0 that returns map containing process information (in this case it is for macOS):

#{pid => 62192,
  priority => #{process => 0,user => -1,process_group => 0},
  pgid => 62192,parent_pid => 62068,uid => 502,gid => 20,
  effective_uid => 502,effective_gid => 20}

The always present field is pid and rest is OS dependant.

Describe alternatives you've considered

Have separate function for each of the information kinds, but as getting that informations from the OS should be fairly cheap, then I think that single call with everything at once should be simpler and more useful. Alternatively we can have info/1 that would allow us to fetching only single fields.