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package devices
import (
"errors"
"io/ioutil"
"os"
"path/filepath"
"github.com/opencontainers/runc/libcontainer/configs"
"golang.org/x/sys/unix"
)
var (
// ErrNotADevice denotes that a file is not a valid linux device.
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 = uint64(stat.Rdev)
major = unix.Major(devNumber)
minor = unix.Minor(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(minor),
Permissions: permissions,
FileMode: os.FileMode(mode),
Uid: stat.Uid,
Gid: stat.Gid,
}, nil
}
// HostDevices returns all devices that can be found under /dev directory.
func HostDevices() ([]*configs.Device, error) {
return GetDevices("/dev")
}
// GetDevices recursively traverses a directory specified by path
// and returns all devices found there.
func GetDevices(path string) ([]*configs.Device, error) {
files, err := ioutilReadDir(path)
if err != nil {
return nil, err
}
var 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
// ".udev" added to address https://github.com/opencontainers/runc/issues/2093
case "pts", "shm", "fd", "mqueue", ".lxc", ".lxd-mounts", ".udev":
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
}
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