120 lines
3.0 KiB
Go
120 lines
3.0 KiB
Go
package devices
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import (
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"errors"
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"fmt"
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"io/ioutil"
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"os"
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"path/filepath"
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"syscall"
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)
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const (
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Wildcard = -1
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)
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var (
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ErrNotADeviceNode = errors.New("not a device node")
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)
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type Device struct {
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Type rune `json:"type,omitempty"`
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Path string `json:"path,omitempty"` // It is fine if this is an empty string in the case that you are using Wildcards
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MajorNumber int64 `json:"major_number,omitempty"` // Use the wildcard constant for wildcards.
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MinorNumber int64 `json:"minor_number,omitempty"` // Use the wildcard constant for wildcards.
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CgroupPermissions string `json:"cgroup_permissions,omitempty"` // Typically just "rwm"
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FileMode os.FileMode `json:"file_mode,omitempty"` // The permission bits of the file's mode
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}
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func GetDeviceNumberString(deviceNumber int64) string {
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if deviceNumber == Wildcard {
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return "*"
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} else {
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return fmt.Sprintf("%d", deviceNumber)
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}
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}
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func (device *Device) GetCgroupAllowString() string {
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return fmt.Sprintf("%c %s:%s %s", device.Type, GetDeviceNumberString(device.MajorNumber), GetDeviceNumberString(device.MinorNumber), device.CgroupPermissions)
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}
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// Given the path to a device and it's cgroup_permissions(which cannot be easilly queried) look up the information about a linux device and return that information as a Device struct.
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func GetDevice(path, cgroupPermissions string) (*Device, error) {
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fileInfo, err := os.Lstat(path)
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if err != nil {
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return nil, err
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}
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var (
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devType rune
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mode = fileInfo.Mode()
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fileModePermissionBits = os.FileMode.Perm(mode)
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)
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switch {
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case mode&os.ModeDevice == 0:
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return nil, ErrNotADeviceNode
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case mode&os.ModeCharDevice != 0:
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fileModePermissionBits |= syscall.S_IFCHR
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devType = 'c'
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default:
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fileModePermissionBits |= syscall.S_IFBLK
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devType = 'b'
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}
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stat_t, ok := fileInfo.Sys().(*syscall.Stat_t)
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if !ok {
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return nil, fmt.Errorf("cannot determine the device number for device %s", path)
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}
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devNumber := int(stat_t.Rdev)
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return &Device{
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Type: devType,
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Path: path,
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MajorNumber: Major(devNumber),
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MinorNumber: Minor(devNumber),
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CgroupPermissions: cgroupPermissions,
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FileMode: fileModePermissionBits,
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}, nil
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}
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func GetHostDeviceNodes() ([]*Device, error) {
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return getDeviceNodes("/dev")
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}
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func getDeviceNodes(path string) ([]*Device, error) {
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files, err := ioutil.ReadDir(path)
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if err != nil {
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return nil, err
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}
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out := []*Device{}
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for _, f := range files {
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if f.IsDir() {
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switch f.Name() {
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case "pts", "shm", "fd":
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continue
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default:
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sub, err := getDeviceNodes(filepath.Join(path, f.Name()))
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if err != nil {
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return nil, err
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}
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out = append(out, sub...)
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continue
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}
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}
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device, err := GetDevice(filepath.Join(path, f.Name()), "rwm")
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if err != nil {
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if err == ErrNotADeviceNode {
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continue
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}
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return nil, err
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}
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out = append(out, device)
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}
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return out, nil
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}
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