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//go:build linux
// +build linux
package system
import (
"os"
"os/exec"
"runtime"
"strings"
"unsafe"
"golang.org/x/sys/unix"
)
type ParentDeathSignal int
func (p ParentDeathSignal) Restore() error {
if p == 0 {
return nil
}
current, err := GetParentDeathSignal()
if err != nil {
return err
}
if p == current {
return nil
}
return p.Set()
}
func (p ParentDeathSignal) Set() error {
return SetParentDeathSignal(uintptr(p))
}
// Deprecated: Execv is not used in runc anymore, it will be removed in v1.2.0.
func Execv(cmd string, args []string, env []string) error {
name, err := exec.LookPath(cmd)
if err != nil {
return err
}
return Exec(name, args, env)
}
func Exec(cmd string, args []string, env []string) error {
for {
err := unix.Exec(cmd, args, env)
if err != unix.EINTR { //nolint:errorlint // unix errors are bare
return &os.PathError{Op: "exec", Path: cmd, Err: err}
}
}
}
func SetParentDeathSignal(sig uintptr) error {
if err := unix.Prctl(unix.PR_SET_PDEATHSIG, sig, 0, 0, 0); err != nil {
return err
}
return nil
}
func GetParentDeathSignal() (ParentDeathSignal, error) {
var sig int
if err := unix.Prctl(unix.PR_GET_PDEATHSIG, uintptr(unsafe.Pointer(&sig)), 0, 0, 0); err != nil {
return -1, err
}
return ParentDeathSignal(sig), nil
}
func SetKeepCaps() error {
if err := unix.Prctl(unix.PR_SET_KEEPCAPS, 1, 0, 0, 0); err != nil {
return err
}
return nil
}
func ClearKeepCaps() error {
if err := unix.Prctl(unix.PR_SET_KEEPCAPS, 0, 0, 0, 0); err != nil {
return err
}
return nil
}
func Setctty() error {
if err := unix.IoctlSetInt(0, unix.TIOCSCTTY, 0); err != nil {
return err
}
return nil
}
// SetSubreaper sets the value i as the subreaper setting for the calling process
func SetSubreaper(i int) error {
return unix.Prctl(unix.PR_SET_CHILD_SUBREAPER, uintptr(i), 0, 0, 0)
}
// GetSubreaper returns the subreaper setting for the calling process
func GetSubreaper() (int, error) {
var i uintptr
if err := unix.Prctl(unix.PR_GET_CHILD_SUBREAPER, uintptr(unsafe.Pointer(&i)), 0, 0, 0); err != nil {
return -1, err
}
return int(i), nil
}
func prepareAt(dir *os.File, path string) (int, string) {
if dir == nil {
return unix.AT_FDCWD, path
}
// Rather than just filepath.Join-ing path here, do it manually so the
// error and handle correctly indicate cases like path=".." as being
// relative to the correct directory. The handle.Name() might end up being
// wrong but because this is (currently) only used in MkdirAllInRoot, that
// isn't a problem.
dirName := dir.Name()
if !strings.HasSuffix(dirName, "/") {
dirName += "/"
}
fullPath := dirName + path
return int(dir.Fd()), fullPath
}
func Openat(dir *os.File, path string, flags int, mode uint32) (*os.File, error) {
dirFd, fullPath := prepareAt(dir, path)
fd, err := unix.Openat(dirFd, path, flags, mode)
if err != nil {
return nil, &os.PathError{Op: "openat", Path: fullPath, Err: err}
}
runtime.KeepAlive(dir)
return os.NewFile(uintptr(fd), fullPath), nil
}
func Mkdirat(dir *os.File, path string, mode uint32) error {
dirFd, fullPath := prepareAt(dir, path)
err := unix.Mkdirat(dirFd, path, mode)
if err != nil {
err = &os.PathError{Op: "mkdirat", Path: fullPath, Err: err}
}
runtime.KeepAlive(dir)
return err
}
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