// during tests.
type OSInterface interface {
	MkdirAll(path string, perm os.FileMode) error
	Symlink(oldname string, newname string) error
	Stat(path string) (os.FileInfo, error)
	Remove(path string) error
	RemoveAll(path string) error
	Create(path string) (*os.File, error)
	Chmod(path string, perm os.FileMode) error
	Hostname() (name string, err error)
	Chtimes(path string, atime time.Time, mtime time.Time) error

	return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Namlen), unsafe.Sizeof(syscall.Dirent{}.Namlen))
}

func direntType(buf []byte) FileMode {
	off := unsafe.Offsetof(syscall.Dirent{}.Type)
	if off >= uintptr(len(buf)) {
		return ^FileMode(0) // unknown
	}
	typ := buf[off]
	switch typ {
	case syscall.DT_BLK:
		return ModeDevice
	case syscall.DT_CHR:
		return ModeDevice | ModeCharDevice

	return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Namlen), unsafe.Sizeof(syscall.Dirent{}.Namlen))
}

func direntType(buf []byte) FileMode {
	off := unsafe.Offsetof(syscall.Dirent{}.Type)
	if off >= uintptr(len(buf)) {
		return ^FileMode(0) // unknown
	}
	typ := buf[off]
	switch typ {
	case syscall.DT_BLK:
		return ModeDevice
	case syscall.DT_CHR:
		return ModeDevice | ModeCharDevice

	return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Namlen), unsafe.Sizeof(syscall.Dirent{}.Namlen))
}

func direntType(buf []byte) FileMode {
	off := unsafe.Offsetof(syscall.Dirent{}.Type)
	if off >= uintptr(len(buf)) {
		return ^FileMode(0) // unknown
	}
	switch syscall.Filetype(buf[off]) {
	case syscall.FILETYPE_BLOCK_DEVICE:
		return ModeDevice
	case syscall.FILETYPE_CHARACTER_DEVICE:

// flags and shouldn't be considered as replacement
// for os.OpenFile().
func LockedOpenFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {
	return lockedOpenFile(path, flag, perm, 0)
}

// Open - Call os.OpenFile
func Open(path string, flag int, perm os.FileMode) (*os.File, error) {
	return os.OpenFile(path, flag, perm)

func (m FileMode) IsDir() bool {
	return m&ModeDir != 0
}

// IsRegular reports whether m describes a regular file.
// That is, it tests that no mode type bits are set.
func (m FileMode) IsRegular() bool {
	return m&ModeType == 0
}

// Perm returns the Unix permission bits in m (m & [ModePerm]).
func (m FileMode) Perm() FileMode {
	return m & ModePerm
}

// flags and shouldn't be considered as replacement
// for os.OpenFile().
func LockedOpenFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {
	return lockedOpenFile(path, flag, perm, syscall.F_SETLKW)
}

// Open - Call os.OpenFile
func Open(path string, flag int, perm os.FileMode) (*os.File, error) {
	return os.OpenFile(path, flag, perm)

pkg os, const ModeAppend FileMode
pkg os, const ModeCharDevice FileMode
pkg os, const ModeDevice FileMode
pkg os, const ModeDir FileMode
pkg os, const ModeExclusive FileMode
pkg os, const ModeIrregular FileMode
pkg os, const ModeNamedPipe FileMode
pkg os, const ModePerm FileMode
pkg os, const ModeSetgid FileMode
pkg os, const ModeSetuid FileMode
pkg os, const ModeSocket FileMode
pkg os, const ModeSticky FileMode

type formatTest struct {
	name    string
	size    int64
	mode    FileMode
	modTime time.Time
	isDir   bool
}

func (fs *formatTest) Name() string {
	return fs.name
}

func (fs *formatTest) Size() int64 {
	return fs.size
}

func (fs *formatTest) Mode() FileMode {
	return fs.mode
}

func (fs *formatTest) ModTime() time.Time {
	return fs.modTime
}

	reclen, ok := direntReclen(buf)
	if !ok {
		return 0, false
	}
	return reclen - uint64(unsafe.Offsetof(syscall.Dirent{}.Name)), true
}

func direntType(buf []byte) FileMode {
	return ^FileMode(0) // unknown