From b68df0b24dd3313395fa8ce0224246eb29438bdf Mon Sep 17 00:00:00 2001
From: Jens Kraemer <jk@jkraemer.net>
Date: Sun, 26 Jul 2020 16:03:23 +0800
Subject: [PATCH] fix creation of multiple identical attachments in outer
 transaction

---
 app/models/attachment.rb     |  3 ++-
 test/unit/attachment_test.rb | 17 +++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/app/models/attachment.rb b/app/models/attachment.rb
index b0cc94cb2..112232c64 100644
--- a/app/models/attachment.rb
+++ b/app/models/attachment.rb
@@ -470,7 +470,8 @@ class Attachment < ActiveRecord::Base
                       .where(digest: self.digest, filesize: self.filesize)
                       .where('id <> ? and disk_filename <> ?',
                              self.id, self.disk_filename)
-                      .first
+                      .order(:id)
+                      .last
         existing.with_lock do
           original_diskfile = self.diskfile
           existing_diskfile = existing.diskfile
diff --git a/test/unit/attachment_test.rb b/test/unit/attachment_test.rb
index 0b3ac06bf..90d0dc679 100644
--- a/test/unit/attachment_test.rb
+++ b/test/unit/attachment_test.rb
@@ -235,6 +235,23 @@ class AttachmentTest < ActiveSupport::TestCase
     assert_not_equal a1.diskfile, a2.diskfile
   end
 
+  def test_identical_attachments_created_in_same_transaction_should_not_end_up_unreadable
+    attachments = []
+    Project.transaction do
+      3.times do
+        a = Attachment.create!(
+          :container => Issue.find(1), :author => User.find(1),
+          :file => mock_file(:filename => 'foo', :content => 'abcde')
+        )
+        attachments << a
+      end
+    end
+    attachments.each do |a|
+      assert a.readable?
+    end
+    assert_equal 1, attachments.map(&:diskfile).uniq.size
+  end
+
   def test_filename_should_be_basenamed
     a = Attachment.new(:file => mock_file(:original_filename => "path/to/the/file"))
     assert_equal 'file', a.filename
-- 
2.20.1