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|
package devices
import (
"fmt"
"os"
"strconv"
)
const (
Wildcard = -1
)
type Device struct {
Rule
// Path to the device.
Path string `json:"path"`
// FileMode permission bits for the device.
FileMode os.FileMode `json:"file_mode"`
// Uid of the device.
Uid uint32 `json:"uid"`
// Gid of the device.
Gid uint32 `json:"gid"`
}
// Permissions is a cgroupv1-style string to represent device access. It
// has to be a string for backward compatibility reasons, hence why it has
// methods to do set operations.
type Permissions string
const (
deviceRead uint = (1 << iota)
deviceWrite
deviceMknod
)
func (p Permissions) toSet() uint {
var set uint
for _, perm := range p {
switch perm {
case 'r':
set |= deviceRead
case 'w':
set |= deviceWrite
case 'm':
set |= deviceMknod
}
}
return set
}
func fromSet(set uint) Permissions {
var perm string
if set&deviceRead == deviceRead {
perm += "r"
}
if set&deviceWrite == deviceWrite {
perm += "w"
}
if set&deviceMknod == deviceMknod {
perm += "m"
}
return Permissions(perm)
}
// Union returns the union of the two sets of Permissions.
func (p Permissions) Union(o Permissions) Permissions {
lhs := p.toSet()
rhs := o.toSet()
return fromSet(lhs | rhs)
}
// Difference returns the set difference of the two sets of Permissions.
// In set notation, A.Difference(B) gives you A\B.
func (p Permissions) Difference(o Permissions) Permissions {
lhs := p.toSet()
rhs := o.toSet()
return fromSet(lhs &^ rhs)
}
// Intersection computes the intersection of the two sets of Permissions.
func (p Permissions) Intersection(o Permissions) Permissions {
lhs := p.toSet()
rhs := o.toSet()
return fromSet(lhs & rhs)
}
// IsEmpty returns whether the set of permissions in a Permissions is
// empty.
func (p Permissions) IsEmpty() bool {
return p == Permissions("")
}
// IsValid returns whether the set of permissions is a subset of valid
// permissions (namely, {r,w,m}).
func (p Permissions) IsValid() bool {
return p == fromSet(p.toSet())
}
type Type rune
const (
WildcardDevice Type = 'a'
BlockDevice Type = 'b'
CharDevice Type = 'c' // or 'u'
FifoDevice Type = 'p'
)
func (t Type) IsValid() bool {
switch t {
case WildcardDevice, BlockDevice, CharDevice, FifoDevice:
return true
default:
return false
}
}
func (t Type) CanMknod() bool {
switch t {
case BlockDevice, CharDevice, FifoDevice:
return true
default:
return false
}
}
func (t Type) CanCgroup() bool {
switch t {
case WildcardDevice, BlockDevice, CharDevice:
return true
default:
return false
}
}
type Rule struct {
// Type of device ('c' for char, 'b' for block). If set to 'a', this rule
// acts as a wildcard and all fields other than Allow are ignored.
Type Type `json:"type"`
// Major is the device's major number.
Major int64 `json:"major"`
// Minor is the device's minor number.
Minor int64 `json:"minor"`
// Permissions is the set of permissions that this rule applies to (in the
// cgroupv1 format -- any combination of "rwm").
Permissions Permissions `json:"permissions"`
// Allow specifies whether this rule is allowed.
Allow bool `json:"allow"`
}
func (d *Rule) CgroupString() string {
var (
major = strconv.FormatInt(d.Major, 10)
minor = strconv.FormatInt(d.Minor, 10)
)
if d.Major == Wildcard {
major = "*"
}
if d.Minor == Wildcard {
minor = "*"
}
return fmt.Sprintf("%c %s:%s %s", d.Type, major, minor, d.Permissions)
}
func (d *Rule) Mkdev() (uint64, error) {
return mkDev(d)
}
|
