storage manager: refactor base_dir option.

Fix it so the `base_dir` option is only required by subclasses that
actually use it. The StorageManager::Mirror class doesn't use it.

app/logical/storage_manager/local.rb

@@ -2,6 +2,14 @@
 class StorageManager::Local < StorageManager
   DEFAULT_PERMISSIONS = 0o644
 
+  attr_reader :base_dir
+
+  # @param base_url [String] the base directory where files are stored (ex: "/home/danbooru/public/data")
+  def initialize(base_dir: nil, **options)
+    @base_dir = base_dir.to_s
+    super(**options)
+  end
+
   def store(io, dest_path)
     temp_path = full_path(dest_path) + "-" + SecureRandom.uuid + ".tmp"
 
@@ -24,4 +32,10 @@ class StorageManager::Local < StorageManager
   def open(path)
     File.open(full_path(path), "r", binmode: true)
   end
+
+  protected
+
+  def full_path(path)
+    File.join(base_dir, path)
+  end
 end

app/logical/storage_manager/null.rb

@@ -1,8 +1,8 @@
 # A null StorageManager that doesn't store files at all. Used for testing or
 # disabling backups.
 class StorageManager::Null < StorageManager
-  def initialize(base_url: "/", base_dir: "/")
-    super
+  def initialize
+    super(base_url: nil)
   end
 
   def store(io, path)

app/logical/storage_manager/rclone.rb

@@ -5,11 +5,12 @@
 # @see https://rclone.org/
 class StorageManager::Rclone < StorageManager
   class Error < StandardError; end
-  attr_reader :remote, :bucket, :rclone_path, :rclone_options
+  attr_reader :remote, :bucket, :rclone_path, :rclone_options, :base_dir
 
-  def initialize(remote:, bucket:, rclone_path: "rclone", rclone_options: {}, **options)
+  def initialize(remote:, bucket:, base_dir: nil, rclone_path: "rclone", rclone_options: {}, **options)
     @remote = remote
     @bucket = bucket
+    @base_dir = base_dir.to_s
     @rclone_path = rclone_path
     @rclone_options = rclone_options
     super(**options)
@@ -37,4 +38,8 @@ class StorageManager::Rclone < StorageManager
   def key(path)
     ":#{remote}:#{bucket}#{full_path(path)}"
   end
+
+  def full_path(path)
+    File.join(base_dir, path)
+  end
 end

app/logical/storage_manager/sftp.rb

@@ -10,10 +10,11 @@ class StorageManager::SFTP < StorageManager
     non_interactive: true
   }
 
-  attr_reader :hosts, :ssh_options
+  attr_reader :hosts, :ssh_options, :base_dir
 
-  def initialize(*hosts, ssh_options: {}, **options)
+  def initialize(*hosts, base_dir: nil, ssh_options: {}, **options)
     @hosts = hosts
+    @base_dir = base_dir.to_s
     @ssh_options = DEFAULT_SSH_OPTIONS.merge(ssh_options)
     super(**options)
   end
@@ -73,4 +74,8 @@ class StorageManager::SFTP < StorageManager
       end
     end
   end
+
+  def full_path(path)
+    File.join(base_dir, path)
+  end
 end