Function GetUsernsForNamespace

pkg/sys/namespace_linux.go:31–38

GetUsernsForNamespace returns a file descriptor that refers to the owning user namespace for the namespace referred to by fd. REF: https://man7.org/linux/man-pages/man2/ioctl_ns.2.html

(fd uintptr)

//
// REF: https://man7.org/linux/man-pages/man2/ioctl_ns.2.html
func GetUsernsForNamespace(fd uintptr) (*os.File, error) {
	fd, _, errno := unix.Syscall(syscall.SYS_IOCTL, fd, uintptr(unix.NS_GET_USERNS), 0)
	if errno != 0 {
		return nil, fmt.Errorf("failed to get user namespace fd: %w", errno)
	}

	return os.NewFile(fd, fmt.Sprintf("/proc/%d/fd/%d", os.Getpid(), fd)), nil
}