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: userns_linux.go
    path of file: ./repos/podman/vendor/github.com/opencontainers/runc/libcontainer/userns
    
    the code of the file until where you have to start completion: package userns

import (
	"bufio"
	"fmt"
	"os"
	"sync"
)

var (
	inUserNS bool
	nsOnce   sync.Once
)

// runningInUserNS detects whether we are currently running in a user namespace.
//
// Originally copied from https://github.com/lxc/incus/blob/e45085dd42f826b3c8c3228e9733c0b6f998eafe/shared/util.go#L678-L700.
func runningInUserNS() boo
    
func uidMapInUserNS(uidMap string) bool {
	if uidMap == "" {
		// File exist but empty (the initial state when userns is created,
		// see user_namespaces(7)).
		return true
	}

	var a, b, c int64
	if _, err := fmt.Sscanf(uidMap, "%d %d %d", &a, &b, &c); err != nil {
		// Assume we are in a regular, non user namespace.
		return false
	}

	// As per user_namespaces(7), /proc/self/uid_map of
	// the initial user namespace shows 0 0 4294967295.
	initNS := a == 0 && b == 0 && c == 4294967295
	return !initNS
}