//go:build linux

package instancectl

import (
	"errors"
	"github.com/carlosframework/platform/internal/safefile"
	"golang.org/x/sys/unix"
	"os"
	"path/filepath"
)

func claimRootDir(dir string) error {
	parent, err := safefile.OpenDir(filepath.Dir(dir))
	if err != nil {
		return err
	}
	defer parent.Close()
	if err := unix.Mkdirat(int(parent.Fd()), filepath.Base(dir), 0700); err != nil && !errors.Is(err, os.ErrExist) {
		return err
	}
	fd, err := unix.Openat2(int(parent.Fd()), filepath.Base(dir), &unix.OpenHow{Flags: unix.O_DIRECTORY | unix.O_RDONLY | unix.O_CLOEXEC, Resolve: unix.RESOLVE_NO_SYMLINKS | unix.RESOLVE_NO_MAGICLINKS})
	if err != nil {
		return err
	}
	defer unix.Close(fd)
	var st unix.Stat_t
	if err := unix.Fstat(fd, &st); err != nil {
		return err
	}
	if st.Uid != uint32(os.Geteuid()) || st.Mode&0022 != 0 {
		return ErrClaimUnit
	}
	return nil
}