From fe934c2f006043cd1657d80fd81100ffdff758b4 Mon Sep 17 00:00:00 2001
From: Olivier Bellone <ob@stripe.com>
Date: Fri, 16 Apr 2021 22:43:57 -0700
Subject: [PATCH] [Fix #9636] Resolve symlinks when excluding directories

---
 CHANGELOG.md                                  |  1 +
 ...lve_symlinks_when_excluding_directories.md |  1 +
 lib/rubocop/target_finder.rb                  |  6 ++++-
 spec/rubocop/target_finder_spec.rb            | 27 +++++++++++++++++++
 spec/support/file_helper.rb                   |  9 +++++++
 5 files changed, 43 insertions(+), 1 deletion(-)
 create mode 100644 changelog/fix_resolve_symlinks_when_excluding_directories.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a3d6cfaece3..1f3c90e789a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5559,3 +5559,4 @@
 [@kachick]: https://github.com/kachick
 [@corroded]: https://github.com/corroded
 [@osyo-manga]: https://github.com/osyo-manga
+[@ob-stripe]: https://github.com/ob-stripe
diff --git a/changelog/fix_resolve_symlinks_when_excluding_directories.md b/changelog/fix_resolve_symlinks_when_excluding_directories.md
new file mode 100644
index 00000000000..5843dc045d5
--- /dev/null
+++ b/changelog/fix_resolve_symlinks_when_excluding_directories.md
@@ -0,0 +1 @@
+* [#9636](https://github.com/rubocop/rubocop/issues/9636): Resolve symlinks when excluding directories. ([@ob-stripe][])
diff --git a/lib/rubocop/target_finder.rb b/lib/rubocop/target_finder.rb
index a643442f341..2e251abb9c1 100644
--- a/lib/rubocop/target_finder.rb
+++ b/lib/rubocop/target_finder.rb
@@ -97,7 +97,11 @@ def wanted_dir_patterns(base_dir, exclude_pattern, flags)
       base_dir = base_dir.gsub('/{}/', '/\{}/')
       dirs = Dir.glob(File.join(base_dir.gsub('/**/', '/\**/'), '*/'), flags)
                 .reject do |dir|
-                  dir.end_with?('/./', '/../') || File.fnmatch?(exclude_pattern, dir, flags)
+                  next true if dir.end_with?('/./', '/../')
+                  next true if File.fnmatch?(exclude_pattern, dir, flags)
+
+                  File.symlink?(dir.chomp('/')) && File.fnmatch?(exclude_pattern,
+                                                                 "#{File.realpath(dir)}/", flags)
                 end
       dirs.flat_map { |dir| wanted_dir_patterns(dir, exclude_pattern, flags) }.unshift(base_dir)
     end
diff --git a/spec/rubocop/target_finder_spec.rb b/spec/rubocop/target_finder_spec.rb
index 449612bf3e5..b1b9ca43d81 100755
--- a/spec/rubocop/target_finder_spec.rb
+++ b/spec/rubocop/target_finder_spec.rb
@@ -447,6 +447,33 @@
         expect(found_basenames).to include('ruby5.rb')
       end
     end
+
+    it 'resolves symlinks when looking for excluded directories' do
+      create_link('link', 'dir1')
+
+      config = instance_double(RuboCop::Config)
+      exclude_property = { 'Exclude' => [File.expand_path('dir1/**/*')] }
+      allow(config).to receive(:for_all_cops).and_return(exclude_property)
+      allow(config_store).to receive(:for).and_return(config)
+
+      expect(found_basenames).not_to include('ruby1.rb')
+      expect(found_basenames).to include('ruby3.rb')
+    end
+
+    it 'can exclude symlinks as well as directories' do
+      Dir.mktmpdir do |tmpdir|
+        create_empty_file(File.join(tmpdir, 'ruby5.rb'))
+        create_link('link', tmpdir)
+
+        config = instance_double(RuboCop::Config)
+        exclude_property = { 'Exclude' => [File.expand_path('link/**/*')] }
+        allow(config).to receive(:for_all_cops).and_return(exclude_property)
+        allow(config_store).to receive(:for).and_return(config)
+
+        expect(found_basenames).not_to include('ruby5.rb')
+        expect(found_basenames).to include('ruby3.rb')
+      end
+    end
   end
 
   describe '#target_files_in_dir' do
diff --git a/spec/support/file_helper.rb b/spec/support/file_helper.rb
index b5418cfb737..d30f417c750 100644
--- a/spec/support/file_helper.rb
+++ b/spec/support/file_helper.rb
@@ -24,4 +24,13 @@ def create_file(file_path, content)
   def create_empty_file(file_path)
     create_file(file_path, '')
   end
+
+  def create_link(link_path, target_path)
+    link_path = File.expand_path(link_path)
+
+    dir_path = File.dirname(link_path)
+    FileUtils.makedirs dir_path unless File.exist?(dir_path)
+
+    FileUtils.symlink(target_path, link_path)
+  end
 end