[GR-18163] Fix repeated calling of methods Dir#each, Dir#each_child and Dir#children

CHANGELOG.md

@@ -5,6 +5,7 @@ New features:
 Bug fixes:
 
 * Add missing thread-safe objects write barriers for `TruffleRuby::ConcurrentMap` (#3179, @eregon).
+* Fix repeated calling of methods `Dir#{each,each_child,children}` (#3464, @andrykonchin).
 
 Compatibility:
 

spec/ruby/core/dir/children_spec.rb

@@ -131,4 +131,17 @@
     children = @dir.children.sort
     children.first.encoding.should equal(Encoding::EUC_KR)
   end
+
+  it "returns the same result when called repeatedly" do
+    @dir = Dir.open DirSpecs.mock_dir
+
+    a = []
+    @dir.each {|dir| a << dir}
+
+    b = []
+    @dir.each {|dir| b << dir}
+
+    a.sort.should == b.sort
+    a.sort.should == DirSpecs.expected_paths
+  end
 end

spec/ruby/core/dir/each_child_spec.rb

@@ -86,6 +86,19 @@
     @dir.each_child { |f| f }.should == @dir
   end
 
+  it "returns the same result when called repeatedly" do
+    @dir = Dir.open DirSpecs.mock_dir
+
+    a = []
+    @dir.each {|dir| a << dir}
+
+    b = []
+    @dir.each {|dir| b << dir}
+
+    a.sort.should == b.sort
+    a.sort.should == DirSpecs.expected_paths
+  end
+
   describe "when no block is given" do
     it "returns an Enumerator" do
       @dir = Dir.new(DirSpecs.mock_dir)

spec/ruby/core/dir/each_spec.rb

@@ -35,6 +35,17 @@
     ls.should include(@dir.read)
   end
 
+  it "returns the same result when called repeatedly" do
+    a = []
+    @dir.each {|dir| a << dir}
+
+    b = []
+    @dir.each {|dir| b << dir}
+
+    a.sort.should == b.sort
+    a.sort.should == DirSpecs.expected_paths
+  end
+
   describe "when no block is given" do
     it "returns an Enumerator" do
       @dir.each.should be_an_instance_of(Enumerator)

src/main/ruby/truffleruby/core/dir.rb

@@ -116,6 +116,8 @@ def closed?
   def each
     return to_enum unless block_given?
 
+    rewind
+
     while s = read
       yield s
     end
@@ -124,6 +126,8 @@ def each
   end
 
   def children
+    rewind
+
     ret = []
     while s = read
       ret << s if s != '.' and s != '..'
@@ -134,6 +138,8 @@ def children
   def each_child
     return to_enum(:each_child) unless block_given?
 
+    rewind
+
     while s = read
       yield s unless s == '.' or s == '..'
     end