From 390097531bd17369f05a23eba58c37b850ac95dd Mon Sep 17 00:00:00 2001
From: George Claghorn <george@basecamp.com>
Date: Sun, 15 Jul 2018 19:58:14 -0400
Subject: Support HTTP Range downloads from disk

Closes #32193.
---
 .../controllers/active_storage/disk_controller.rb  | 29 +++++++++++-----------
 .../lib/active_storage/service/disk_service.rb     |  8 +++---
 .../test/controllers/disk_controller_test.rb       | 13 ++++++++--
 3 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/activestorage/app/controllers/active_storage/disk_controller.rb b/activestorage/app/controllers/active_storage/disk_controller.rb
index 63918eb6f4..436cd0ccd8 100644
--- a/activestorage/app/controllers/active_storage/disk_controller.rb
+++ b/activestorage/app/controllers/active_storage/disk_controller.rb
@@ -5,23 +5,14 @@
 # Always go through the BlobsController, or your own authenticated controller, rather than directly
 # to the service url.
 class ActiveStorage::DiskController < ActiveStorage::BaseController
-  include ActionController::Live
-
   skip_forgery_protection
 
   def show
     if key = decode_verified_key
-      response.headers["Content-Type"] = params[:content_type] || DEFAULT_SEND_FILE_TYPE
-      response.headers["Content-Disposition"] = params[:disposition] || DEFAULT_SEND_FILE_DISPOSITION
-
-      disk_service.download key do |chunk|
-        response.stream.write chunk
-      end
+      serve_file disk_service.path_for(key), content_type: params[:content_type], disposition: params[:disposition]
     else
       head :not_found
     end
-  ensure
-    response.stream.close
   end
 
   def update
@@ -32,13 +23,9 @@ class ActiveStorage::DiskController < ActiveStorage::BaseController
       else
         head :unprocessable_entity
       end
-    else
-      head :not_found
     end
   rescue ActiveStorage::IntegrityError
     head :unprocessable_entity
-  ensure
-    response.stream.close
   end
 
   private
@@ -51,6 +38,20 @@ class ActiveStorage::DiskController < ActiveStorage::BaseController
       ActiveStorage.verifier.verified(params[:encoded_key], purpose: :blob_key)
     end
 
+    def serve_file(path, content_type:, disposition:)
+      Rack::File.new(nil).serving(request, path).tap do |(status, headers, body)|
+        self.status = status
+        self.response_body = body
+
+        headers.each do |name, value|
+          response.headers[name] = value
+        end
+
+        response.headers["Content-Type"] = content_type || DEFAULT_SEND_FILE_TYPE
+        response.headers["Content-Disposition"] = disposition || DEFAULT_SEND_FILE_DISPOSITION
+      end
+    end
+
 
     def decode_verified_token
       ActiveStorage.verifier.verified(params[:encoded_token], purpose: :blob_token)
diff --git a/activestorage/lib/active_storage/service/disk_service.rb b/activestorage/lib/active_storage/service/disk_service.rb
index b1b6f1ddcf..9f304b7e01 100644
--- a/activestorage/lib/active_storage/service/disk_service.rb
+++ b/activestorage/lib/active_storage/service/disk_service.rb
@@ -117,11 +117,11 @@ module ActiveStorage
       { "Content-Type" => content_type }
     end
 
-    private
-      def path_for(key)
-        File.join root, folder_for(key), key
-      end
+    def path_for(key) #:nodoc:
+      File.join root, folder_for(key), key
+    end
 
+    private
       def folder_for(key)
         [ key[0..1], key[2..3] ].join("/")
       end
diff --git a/activestorage/test/controllers/disk_controller_test.rb b/activestorage/test/controllers/disk_controller_test.rb
index 9af7c83bdf..32b930730d 100644
--- a/activestorage/test/controllers/disk_controller_test.rb
+++ b/activestorage/test/controllers/disk_controller_test.rb
@@ -6,8 +6,8 @@ require "database/setup"
 class ActiveStorage::DiskControllerTest < ActionDispatch::IntegrationTest
   test "showing blob inline" do
     blob = create_blob
-
     get blob.service_url
+    assert_response :ok
     assert_equal "inline; filename=\"hello.txt\"; filename*=UTF-8''hello.txt", response.headers["Content-Disposition"]
     assert_equal "text/plain", response.headers["Content-Type"]
     assert_equal "Hello world!", response.body
@@ -15,13 +15,22 @@ class ActiveStorage::DiskControllerTest < ActionDispatch::IntegrationTest
 
   test "showing blob as attachment" do
     blob = create_blob
-
     get blob.service_url(disposition: :attachment)
+    assert_response :ok
     assert_equal "attachment; filename=\"hello.txt\"; filename*=UTF-8''hello.txt", response.headers["Content-Disposition"]
     assert_equal "text/plain", response.headers["Content-Type"]
     assert_equal "Hello world!", response.body
   end
 
+  test "showing blob range inline" do
+    blob = create_blob
+    get blob.service_url, headers: { "Range" => "bytes=5-9" }
+    assert_response :partial_content
+    assert_equal "inline; filename=\"hello.txt\"; filename*=UTF-8''hello.txt", response.headers["Content-Disposition"]
+    assert_equal "text/plain", response.headers["Content-Type"]
+    assert_equal " worl", response.body
+  end
+
 
   test "directly uploading blob with integrity" do
     data = "Something else entirely!"
-- 
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