You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: sig_action.rs
    path of file: ./repos/occlum/src/libos/src/signal
    
    the code of the file until where you have to start completion: use super::c_types::{sigaction_t, SIG_DFL, SIG_IGN};
use super::constants::*;
use super::{SigNum, SigSet};
use crate::prelude::*;

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum SigAction {
    Dfl, // Default action
    Ign, // Ignore this signal
    User {
        // User-given handler
        handler_addr: usize,
        flags: SigActionFlags,
        restorer_addr: usize,
        mask: SigSet,
    },
}

impl Default for SigAction {
    fn default() -> Self {
        SigAction::Dfl
    }
}

impl SigAction {
    pub fn fr
    
    pub fn from_signum(num: SigNum) -> SigDefaultAction {
        match num {
            SIGABRT | // = SIGIOT
            SIGBUS  |
            SIGFPE  |
            SIGILL  |
            SIGQUIT |
            SIGSEGV |
            SIGSYS  | // = SIGUNUSED
            SIGTRAP |
            SIGXCPU |
            SIGXFSZ
                => SigDefaultAction::Core,
            SIGCHLD |
            SIGURG  |
            SIGWINCH
                => SigDefaultAction::Ign,
            SIGCONT
                => SigDefaultAction::Cont,
            SIGSTOP |
            SIGTSTP |
            SIGTTIN |
            SIGTTOU
                => SigDefaultAction::Stop,
            _
                => SigDefaultAction::Term,
        }
    }