vendor/github.com/opencontainers/runc/libcontainer/devices/devices_unix.go

   1 // +build linux freebsd
   2
   3 package devices
   4
   5 import (
   6         "errors"
   7         "fmt"
   8         "io/ioutil"
   9         "os"
  10         "path/filepath"
  11         "syscall"
  12
  13         "github.com/opencontainers/runc/libcontainer/configs"
  14 )
  15
  16 var (
  17         ErrNotADevice = errors.New("not a device node")
  18 )
  19
  20 // Testing dependencies
  21 var (
  22         osLstat       = os.Lstat
  23         ioutilReadDir = ioutil.ReadDir
  24 )
  25
  26 // 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.
  27 func DeviceFromPath(path, permissions string) (*configs.Device, error) {
  28         fileInfo, err := osLstat(path)
  29         if err != nil {
  30                 return nil, err
  31         }
  32         var (
  33                 devType                rune
  34                 mode                   = fileInfo.Mode()
  35                 fileModePermissionBits = os.FileMode.Perm(mode)
  36         )
  37         switch {
  38         case mode&os.ModeDevice == 0:
  39                 return nil, ErrNotADevice
  40         case mode&os.ModeCharDevice != 0:
  41                 fileModePermissionBits |= syscall.S_IFCHR
  42                 devType = 'c'
  43         default:
  44                 fileModePermissionBits |= syscall.S_IFBLK
  45                 devType = 'b'
  46         }
  47         stat_t, ok := fileInfo.Sys().(*syscall.Stat_t)
  48         if !ok {
  49                 return nil, fmt.Errorf("cannot determine the device number for device %s", path)
  50         }
  51         devNumber := int(stat_t.Rdev)
  52         return &configs.Device{
  53                 Type:        devType,
  54                 Path:        path,
  55                 Major:       Major(devNumber),
  56                 Minor:       Minor(devNumber),
  57                 Permissions: permissions,
  58                 FileMode:    fileModePermissionBits,
  59                 Uid:         stat_t.Uid,
  60                 Gid:         stat_t.Gid,
  61         }, nil
  62 }
  63
  64 func HostDevices() ([]*configs.Device, error) {
  65         return getDevices("/dev")
  66 }
  67
  68 func getDevices(path string) ([]*configs.Device, error) {
  69         files, err := ioutilReadDir(path)
  70         if err != nil {
  71                 return nil, err
  72         }
  73         out := []*configs.Device{}
  74         for _, f := range files {
  75                 switch {
  76                 case f.IsDir():
  77                         switch f.Name() {
  78                         // ".lxc" & ".lxd-mounts" added to address https://github.com/lxc/lxd/issues/2825
  79                         case "pts", "shm", "fd", "mqueue", ".lxc", ".lxd-mounts":
  80                                 continue
  81                         default:
  82                                 sub, err := getDevices(filepath.Join(path, f.Name()))
  83                                 if err != nil {
  84                                         return nil, err
  85                                 }
  86
  87                                 out = append(out, sub...)
  88                                 continue
  89                         }
  90                 case f.Name() == "console":
  91                         continue
  92                 }
  93                 device, err := DeviceFromPath(filepath.Join(path, f.Name()), "rwm")
  94                 if err != nil {
  95                         if err == ErrNotADevice {
  96                                 continue
  97                         }
  98                         if os.IsNotExist(err) {
  99                                 continue
 100                         }
 101                         return nil, err
 102                 }
 103                 out = append(out, device)
 104         }
 105         return out, nil
 106 }