//go:build linux

package host

import (
	"errors"
	"os"

	"github.com/carlosframework/platform/internal/hostwrite"
	"github.com/carlosframework/platform/internal/safefile"
	"golang.org/x/sys/unix"
)

func prepareClaimDatabaseOwner(path string, uid, gid int) error {
	for _, suffix := range []string{"", "-wal", "-shm"} {
		name := path + suffix
		f, err := safefile.OpenFile(name, os.O_RDWR, 0)
		created := false
		if errors.Is(err, unix.ENOENT) {
			if suffix != "" {
				continue
			}
			f, err = safefile.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
			created = err == nil
		}
		if err != nil {
			return err
		}
		err = func() error {
			defer f.Close()
			fd := int(f.Fd())
			var stat unix.Stat_t
			if err := unix.Fstat(fd, &stat); err != nil {
				return err
			}
			if stat.Mode&unix.S_IFMT != unix.S_IFREG || stat.Nlink != 1 || (!created && int(stat.Uid) != uid) {
				return hostwrite.ErrUnavailable
			}
			if created && os.Geteuid() == 0 {
				if err := unix.Fchown(fd, uid, gid); err != nil {
					return err
				}
			}
			return unix.Fchmod(fd, 0600)
		}()
		if err != nil {
			return err
		}
	}
	return nil
}