Extend PublishedStorage interface for Acquire-By-Hash

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

files/public.go

@@ -247,3 +247,33 @@ func (storage *PublishedStorage) Filelist(prefix string) ([]string, error) {
 func (storage *PublishedStorage) RenameFile(oldName, newName string) error {
 	return os.Rename(filepath.Join(storage.rootPath, oldName), filepath.Join(storage.rootPath, newName))
 }
+
+// SymLink creates a symbolic link, which can be read with ReadLink
+func (storage *PublishedStorage) SymLink(src string, dst string) error {
+	return os.Symlink(src, filepath.Join(storage.rootPath, dst))
+}
+
+// HardLink creates a hardlink of a file
+func (storage *PublishedStorage) HardLink(src string, dst string) error {
+	return os.Link(filepath.Join(storage.rootPath, src), filepath.Join(storage.rootPath, dst))
+}
+
+// FileExists returns true if path exists
+func (storage *PublishedStorage) FileExists(path string) bool {
+	list, err := storage.Filelist(filepath.Dir(path))
+	if err != nil {
+		return false
+	}
+	f := filepath.Base(path)
+	for _, i := range list {
+		if i == f {
+			return true
+		}
+	}
+	return false
+}
+
+// ReadLink returns the symbolic link pointed to by path
+func (storage *PublishedStorage) ReadLink(path string) (string, error) {
+	return os.Readlink(path)
+}