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linux.go
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linux.go
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//go:build linux
// +build linux
package system
import (
"os"
"os/exec"
"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))
}
// Eaccess is similar to unix.Access except for setuid/setgid binaries
// it checks against the effective (rather than real) uid and gid.
func Eaccess(path string) error {
err := unix.Faccessat2(unix.AT_FDCWD, path, unix.X_OK, unix.AT_EACCESS)
if err != unix.ENOSYS && err != unix.EPERM { //nolint:errorlint // unix errors are bare
return err
}
// Faccessat2() not available; check if we are a set[ug]id binary.
if os.Getuid() == os.Geteuid() && os.Getgid() == os.Getegid() {
// For a non-set[ug]id binary, use access(2).
return unix.Access(path, unix.X_OK)
}
// For a setuid/setgid binary, there is no fallback way
// so assume we can execute the binary.
return nil
}
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
}