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package container
import (
"encoding/gob"
"fmt"
"os"
"path"
. "syscall"
"unsafe"
)
func init() { gob.Register(new(MountDevOp)) }
// Dev appends an [Op] that mounts a subset of host /dev.
func (f *Ops) Dev(target *Absolute, mqueue bool) *Ops {
*f = append(*f, &MountDevOp{target, mqueue, false})
return f
}
// DevWritable appends an [Op] that mounts a writable subset of host /dev.
// There is usually no good reason to write to /dev, so this should always be followed by a [RemountOp].
func (f *Ops) DevWritable(target *Absolute, mqueue bool) *Ops {
*f = append(*f, &MountDevOp{target, mqueue, true})
return f
}
// MountDevOp mounts a subset of host /dev on container path Target.
// If Mqueue is true, a private instance of [FstypeMqueue] is mounted.
// If Write is true, the resulting mount point is left writable.
type MountDevOp struct {
Target *Absolute
Mqueue bool
Write bool
}
func (d *MountDevOp) early(*setupState) error { return nil }
func (d *MountDevOp) apply(state *setupState) error {
if d.Target == nil {
return EBADE
}
target := toSysroot(d.Target.String())
if err := mountTmpfs(SourceTmpfsDevtmpfs, target, MS_NOSUID|MS_NODEV, 0, state.ParentPerm); err != nil {
return err
}
for _, name := range []string{"null", "zero", "full", "random", "urandom", "tty"} {
targetPath := path.Join(target, name)
if err := ensureFile(targetPath, 0444, state.ParentPerm); err != nil {
return err
}
if err := hostProc.bindMount(
toHost(FHSDev+name),
targetPath,
0,
true,
); err != nil {
return err
}
}
for i, name := range []string{"stdin", "stdout", "stderr"} {
if err := os.Symlink(
FHSProc+"self/fd/"+string(rune(i+'0')),
path.Join(target, name),
); err != nil {
return wrapErrSelf(err)
}
}
for _, pair := range [][2]string{
{FHSProc + "self/fd", "fd"},
{FHSProc + "kcore", "core"},
{"pts/ptmx", "ptmx"},
} {
if err := os.Symlink(pair[0], path.Join(target, pair[1])); err != nil {
return wrapErrSelf(err)
}
}
devPtsPath := path.Join(target, "pts")
for _, name := range []string{path.Join(target, "shm"), devPtsPath} {
if err := os.Mkdir(name, state.ParentPerm); err != nil {
return wrapErrSelf(err)
}
}
if err := Mount(SourceDevpts, devPtsPath, FstypeDevpts, MS_NOSUID|MS_NOEXEC,
"newinstance,ptmxmode=0666,mode=620"); err != nil {
return wrapErrSuffix(err,
fmt.Sprintf("cannot mount devpts on %q:", devPtsPath))
}
if state.RetainSession {
var buf [8]byte
if _, _, errno := Syscall(SYS_IOCTL, 1, TIOCGWINSZ, uintptr(unsafe.Pointer(&buf[0]))); errno == 0 {
consolePath := path.Join(target, "console")
if err := ensureFile(consolePath, 0444, state.ParentPerm); err != nil {
return err
}
if name, err := os.Readlink(hostProc.stdout()); err != nil {
return wrapErrSelf(err)
} else if err = hostProc.bindMount(
toHost(name),
consolePath,
0,
false,
); err != nil {
return err
}
}
}
if d.Mqueue {
mqueueTarget := path.Join(target, "mqueue")
if err := os.Mkdir(mqueueTarget, state.ParentPerm); err != nil {
return wrapErrSelf(err)
}
if err := Mount(SourceMqueue, mqueueTarget, FstypeMqueue, MS_NOSUID|MS_NOEXEC|MS_NODEV, zeroString); err != nil {
return wrapErrSuffix(err, "cannot mount mqueue:")
}
}
if d.Write {
return nil
}
return wrapErrSuffix(hostProc.remount(target, MS_RDONLY),
fmt.Sprintf("cannot remount %q:", target))
}
func (d *MountDevOp) Is(op Op) bool { vd, ok := op.(*MountDevOp); return ok && *d == *vd }
func (*MountDevOp) prefix() string { return "mounting" }
func (d *MountDevOp) String() string {
if d.Mqueue {
return fmt.Sprintf("dev on %q with mqueue", d.Target)
}
return fmt.Sprintf("dev on %q", d.Target)
}
|
