package devices
 
 import (

 	"errors"
 	"io/ioutil"

 	"os"

 	"path/filepath"

 	"github.com/opencontainers/runc/libcontainer/configs"

 
 	"golang.org/x/sys/unix"

 )
 

 var (

 	ErrNotADevice = errors.New("not a device node")

 )
 

 // Testing dependencies
 var (

 	unixLstat     = unix.Lstat

 	ioutilReadDir = ioutil.ReadDir
 )
 

 // Given the path to a device and its cgroup_permissions(which cannot be easily queried) look up the information about a linux device and return that information as a Device struct.

 func DeviceFromPath(path, permissions string) (*configs.Device, error) {

 	var stat unix.Stat_t
 	err := unixLstat(path, &stat)

 	if err != nil {
 		return nil, err
 	}

 	var (

 		devNumber = stat.Rdev
 		major     = unix.Major(devNumber)

 	)

 	if major == 0 {

 		return nil, ErrNotADevice

 	}

 
 	var (
 		devType rune
 		mode    = stat.Mode
 	)
 	switch {
 	case mode&unix.S_IFBLK == unix.S_IFBLK:
 		devType = 'b'
 	case mode&unix.S_IFCHR == unix.S_IFCHR:
 		devType = 'c'

 	}

 	return &configs.Device{
 		Type:        devType,
 		Path:        path,

 		Major:       int64(major),
 		Minor:       int64(unix.Minor(devNumber)),

 		Permissions: permissions,

 		FileMode:    os.FileMode(mode),
 		Uid:         stat.Uid,
 		Gid:         stat.Gid,

 	}, nil

 }
 

 func HostDevices() ([]*configs.Device, error) {
 	return getDevices("/dev")

 }
 

 func getDevices(path string) ([]*configs.Device, error) {

 	files, err := ioutilReadDir(path)

 	if err != nil {
 		return nil, err

 	}

 	out := []*configs.Device{}

 	for _, f := range files {

 		switch {
 		case f.IsDir():

 			switch f.Name() {

 			// ".lxc" & ".lxd-mounts" added to address https://github.com/lxc/lxd/issues/2825
 			case "pts", "shm", "fd", "mqueue", ".lxc", ".lxd-mounts":

 				continue
 			default:

 				sub, err := getDevices(filepath.Join(path, f.Name()))

 				if err != nil {
 					return nil, err
 				}
 
 				out = append(out, sub...)
 				continue
 			}

 		case f.Name() == "console":
 			continue

 		}

 		device, err := DeviceFromPath(filepath.Join(path, f.Name()), "rwm")

 		if err != nil {

 			if err == ErrNotADevice {

 				continue
 			}

 			if os.IsNotExist(err) {
 				continue
 			}

 			return nil, err
 		}
 		out = append(out, device)
 	}
 	return out, nil
 }