From 152c4b07248d4aed4b734721bd634e546a89ef19 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 6 Jul 2017 15:38:01 +0200
Subject: Compute checksum and byte_size client side

Then we can add integrity checks on uploads to prevent errors in
transport.
---
 lib/active_storage/blob.rb                 | 18 +++++++++++++++---
 lib/active_storage/service/disk_service.rb | 10 ----------
 lib/active_storage/service/gcs_service.rb  | 14 --------------
 lib/active_storage/service/s3_service.rb   | 10 ----------
 4 files changed, 15 insertions(+), 37 deletions(-)

(limited to 'lib')

diff --git a/lib/active_storage/blob.rb b/lib/active_storage/blob.rb
index 4ce344e2a1..b10dc2c771 100644
--- a/lib/active_storage/blob.rb
+++ b/lib/active_storage/blob.rb
@@ -42,10 +42,10 @@ class ActiveStorage::Blob < ActiveRecord::Base
 
 
   def upload(io)
-    service.upload(key, io)
+    self.checksum  = compute_checksum_in_chunks(io)
+    self.byte_size = io.size
 
-    self.checksum  = service.checksum(key)
-    self.byte_size = service.byte_size(key)
+    service.upload(key, io)
   end
 
   def download
@@ -65,4 +65,16 @@ class ActiveStorage::Blob < ActiveRecord::Base
   def purge_later
     ActiveStorage::PurgeJob.perform_later(self)
   end
+
+
+  private
+    def compute_checksum_in_chunks(io)
+      Digest::MD5.new.tap do |checksum|
+        while chunk = io.read(5.megabytes)
+          checksum << chunk
+        end
+
+        io.rewind
+      end.base64digest
+    end
 end
diff --git a/lib/active_storage/service/disk_service.rb b/lib/active_storage/service/disk_service.rb
index 7981226a1e..98e0f5eb7f 100644
--- a/lib/active_storage/service/disk_service.rb
+++ b/lib/active_storage/service/disk_service.rb
@@ -36,7 +36,6 @@ class ActiveStorage::Service::DiskService < ActiveStorage::Service
     File.exist? path_for(key)
   end
 
-
   def url(key, expires_in:, disposition:, filename:)
     verified_key_with_expiration = ActiveStorage::VerifiedKeyWithExpiration.encode(key, expires_in: expires_in)
 
@@ -47,15 +46,6 @@ class ActiveStorage::Service::DiskService < ActiveStorage::Service
     end
   end
 
-  def byte_size(key)
-    File.size path_for(key)
-  end
-
-  def checksum(key)
-    Digest::MD5.file(path_for(key)).hexdigest
-  end
-
-
   private
     def path_for(key)
       File.join root, folder_for(key), key
diff --git a/lib/active_storage/service/gcs_service.rb b/lib/active_storage/service/gcs_service.rb
index c2f520d996..c725afb35c 100644
--- a/lib/active_storage/service/gcs_service.rb
+++ b/lib/active_storage/service/gcs_service.rb
@@ -28,27 +28,13 @@ class ActiveStorage::Service::GCSService < ActiveStorage::Service
     file_for(key).present?
   end
 
-
   def url(key, expires_in:, disposition:, filename:)
     file_for(key).signed_url(expires: expires_in) + "&" +
       { "response-content-disposition" => "#{disposition}; filename=\"#{filename}\"" }.to_query
   end
 
-  def byte_size(key)
-    file_for(key).size
-  end
-
-  def checksum(key)
-    convert_to_hex base64: file_for(key).md5
-  end
-
-
   private
     def file_for(key)
       bucket.file(key)
     end
-
-    def convert_to_hex(base64:)
-      base64.unpack("m0").first.unpack("H*").first
-    end
 end
diff --git a/lib/active_storage/service/s3_service.rb b/lib/active_storage/service/s3_service.rb
index c94f5ddc63..cb08893c0e 100644
--- a/lib/active_storage/service/s3_service.rb
+++ b/lib/active_storage/service/s3_service.rb
@@ -28,21 +28,11 @@ class ActiveStorage::Service::S3Service < ActiveStorage::Service
     object_for(key).exists?
   end
 
-
   def url(key, expires_in:, disposition:, filename:)
     object_for(key).presigned_url :get, expires_in: expires_in,
       response_content_disposition: "#{disposition}; filename=\"#{filename}\""
   end
 
-  def byte_size(key)
-    object_for(key).size
-  end
-
-  def checksum(key)
-    object_for(key).etag.remove(/"/)
-  end
-
-
   private
     def object_for(key)
       bucket.object(key)
-- 
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