Move existing dirs to a temp location while restore

Instead of renaming existing storage directories to a timestamped
format, create a timestamped directory in a temporary location and move
the individual files and folders inside storage directories to it. This
helps us with nested storage directories.

lib/backup/artifacts.rb

@@ -5,9 +5,5 @@ module Backup
     def initialize
       super('artifacts', JobArtifactUploader.root)
     end
-
-    def create_files_dir
-      Dir.mkdir(app_files_dir, 0700)
-    end
   end
 end

lib/backup/builds.rb

@@ -5,9 +5,5 @@ module Backup
     def initialize
       super('builds', Settings.gitlab_ci.builds_path)
     end
-
-    def create_files_dir
-      Dir.mkdir(app_files_dir, 0700)
-    end
   end
 end

lib/backup/files.rb

 require 'open3'
+require_relative 'helper'
 module Backup
   class Files
+    include Backup::Helper
+
     attr_reader :name, :app_files_dir, :backup_tarball, :files_parent_dir
     def initialize(name, app_files_dir)
@@ -35,15 +38,22 @@ module Backup
     def restore
       backup_existing_files_dir
-      create_files_dir
-      run_pipeline!([%w(gzip -cd), %W(tar -C #{app_files_dir} -xf -)], in: backup_tarball)
+      run_pipeline!([%w(gzip -cd), %W(tar --unlink-first --recursive-unlink -C #{app_files_dir} -xf -)], in: backup_tarball)
     end
     def backup_existing_files_dir
-      timestamped_files_path = File.join(files_parent_dir, "#{name}.#{Time.now.to_i}")
+      timestamped_files_path = File.join(Gitlab.config.backup.path, "tmp", "#{name}.#{Time.now.to_i}")
       if File.exist?(app_files_dir)
-        FileUtils.mv(app_files_dir, File.expand_path(timestamped_files_path))
+        # Move all files in the existing repos directory except . and .. to
+        # repositories.old.<timestamp> directory
+        FileUtils.mkdir_p(timestamped_files_path, mode: 0700)
+        files = Dir.glob(File.join(app_files_dir, "*"), File::FNM_DOTMATCH) - [File.join(app_files_dir, "."), File.join(app_files_dir, "..")]
+        begin
+          FileUtils.mv(files, timestamped_files_path)
+        rescue Errno::EACCES
+          access_denied_error(app_files_dir)
+        end
       end
     end

lib/backup/helper.rb

+module Backup
+  module Helper
+    def access_denied_error(path)
+      message = <<~EOS
+
+      ### NOTICE ###
+      As part of restore, the task tried to move existing content from #{path}.
+      However, it seems that directory contains files/folders that are not owned
+      by the user #{Gitlab.config.gitlab.user}. To proceed, please move the files
+      or folders inside #{path} to a secure location so that #{path} is empty and
+      run restore task again.
+
+      EOS
+      raise message
+    end
+  end
+end

lib/backup/lfs.rb

@@ -5,9 +5,5 @@ module Backup
     def initialize
       super('lfs', Settings.lfs.storage_path)
     end
-
-    def create_files_dir
-      Dir.mkdir(app_files_dir, 0700)
-    end
   end
 end

lib/backup/pages.rb

@@ -5,9 +5,5 @@ module Backup
     def initialize
       super('pages', Gitlab.config.pages.path)
     end
-
-    def create_files_dir
-      Dir.mkdir(app_files_dir, 0700)
-    end
   end
 end

lib/backup/registry.rb

@@ -5,9 +5,5 @@ module Backup
     def initialize
       super('registry', Settings.registry.path)
     end
-
-    def create_files_dir
-      Dir.mkdir(app_files_dir, 0700)
-    end
   end
 end

lib/backup/repository.rb

 require 'yaml'
+require_relative 'helper'
 module Backup
   class Repository
+    include Backup::Helper
     # rubocop:disable Metrics/AbcSize
+
     def dump
       prepare
@@ -63,18 +66,27 @@ module Backup
       end
     end
-    def restore
+    def prepare_directories
       Gitlab.config.repositories.storages.each do |name, repository_storage|
         path = repository_storage.legacy_disk_path
         next unless File.exist?(path)
-        # Move repos dir to 'repositories.old' dir
-        bk_repos_path = File.join(path, '..', 'repositories.old.' + Time.now.to_i.to_s)
-        FileUtils.mv(path, bk_repos_path)
-        # This is expected from gitlab:check
-        FileUtils.mkdir_p(path, mode: 02770)
+        # Move all files in the existing repos directory except . and .. to
+        # repositories.old.<timestamp> directory
+        bk_repos_path = File.join(Gitlab.config.backup.path, "tmp", "#{name}-repositories.old." + Time.now.to_i.to_s)
+        FileUtils.mkdir_p(bk_repos_path, mode: 0700)
+        files = Dir.glob(File.join(path, "*"), File::FNM_DOTMATCH) - [File.join(path, "."), File.join(path, "..")]
+
+        begin
+          FileUtils.mv(files, bk_repos_path)
+        rescue Errno::EACCES
+          access_denied_error(path)
+        end
       end
+    end
+    def restore
+      prepare_directories
       Project.find_each(batch_size: 1000) do |project|
         progress.print " * #{display_repo_path(project)} ... "
         path_to_project_repo = path_to_repo(project)

lib/backup/uploads.rb

@@ -5,9 +5,5 @@ module Backup
     def initialize
       super('uploads', Rails.root.join('public/uploads'))
     end
-
-    def create_files_dir
-      Dir.mkdir(app_files_dir)
-    end
   end
 end

spec/lib/backup/repository_spec.rb

@@ -7,6 +7,8 @@ describe Backup::Repository do
   before do
     allow(progress).to receive(:puts)
     allow(progress).to receive(:print)
+    allow(FileUtils).to receive(:mkdir_p).and_return(true)
+    allow(FileUtils).to receive(:mv).and_return(true)
     allow_any_instance_of(String).to receive(:color) do |string, _color|
       string