transfer

type DataFS interface {
	Open(path string) (ReadFile, error)

	// CreateExclusive creates path for writing, failing if it exists.
	CreateExclusive(path string) (WriteFile, error)

	// Rename moves oldPath over newPath, replacing any existing entry
	// atomically.
	Rename(oldPath, newPath string) error

	Remove(path string) error
}

type FS interface {
	PathFS
	MetaFS
	DataFS
	LinkFS
}

type HostFS struct{}

type LinkFS interface {
	Symlink(target, link string) error
	Readlink(path string) (string, error)

	// Resolve canonicalizes path, following symbolic links.
	Resolve(path string) (string, error)
}

type MetaFS interface {
	Lstat(path string) (fs.FileInfo, error)
	Stat(path string) (fs.FileInfo, error)
	ReadDir(path string) ([]fs.FileInfo, error)
	Mkdir(path string) error
	MkdirAll(path string) error
	Chmod(path string, mode fs.FileMode) error

	// SameFile reports whether two stat results name the same file, when
	// the filesystem can tell; a side that cannot may always report false.
	SameFile(a, b fs.FileInfo) bool
}

type PathFS interface {
	Abs(path string) (string, error)
	Join(elem ...string) string
	Dir(path string) string
	Base(path string) string

	// Contains reports whether path is root itself or lies under it.
	Contains(root, path string) bool
}

type ReadFile interface {
	io.ReadCloser
	Stat() (fs.FileInfo, error)
}

type WriteFile interface {
	io.WriteCloser
	Chmod(mode fs.FileMode) error
	Sync() error
}