Extend PublishedStorage interface for Acquire-By-Hash

Signed-off-by: André Roth <neolynx@gmail.com>

aptly/interfaces.go

@@ -73,6 +73,14 @@ type PublishedStorage interface {
 	Filelist(prefix string) ([]string, error)
 	// RenameFile renames (moves) file
 	RenameFile(oldName, newName string) error
+	// SymLink creates a symbolic link, which can be read with ReadLink
+	SymLink(src string, dst string) error
+	// HardLink creates a hardlink of a file
+	HardLink(src string, dst string) error
+	// FileExists returns true if path exists
+	FileExists(path string) bool
+	// ReadLink returns the symbolic link pointed to by path
+	ReadLink(path string) (string, error)
 }
 
 // FileSystemPublishedStorage is published storage on filesystem