merge revision(s) 61639: [Backport #14323]

	net/ftp: fix FrozenError in BufferedSocket

	I noticed this bug while working on something else with
	RUBYOPT=-d on, existing test cases all passed with it.

	Note: I use String.new because it is the local style, here,
	I prefer +'' (or ''.b, for a future commit)

	* lib/net/ftp.rb (BufferedSocket#read): use String.new
	* test/net/ftp/test_buffered_socket.rb (test_read_nil): new test
	  [Bug #14323]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@62943 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

4 files changed, 22 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 2bfb9f9a34..79aa6dd5f1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+Sun Mar 28 14:40:25 2018  Eric Wong  <normalperson@yhbt.net>
+
+	net/ftp: fix FrozenError in BufferedSocket
+
+	I noticed this bug while working on something else with
+	RUBYOPT=-d on, existing test cases all passed with it.
+
+	Note: I use String.new because it is the local style, here,
+	I prefer +'' (or ''.b, for a future commit)
+
+	* lib/net/ftp.rb (BufferedSocket#read): use String.new
+	* test/net/ftp/test_buffered_socket.rb (test_read_nil): new test
+	  [Bug #14323]
+
 Thu Mar 28 14:29:26 2018  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	clean autogenerated files
diff --git a/lib/net/ftp.rb b/lib/net/ftp.rb
index 0437e9504e..b25db9ad3c 100644
--- a/lib/net/ftp.rb
+++ b/lib/net/ftp.rb
@@ -1297,7 +1297,7 @@ module Net
           s = super(len, String.new, true)
           return s.empty? ? nil : s
         else
-          result = ""
+          result = String.new
           while s = super(DEFAULT_BLOCKSIZE, String.new, true)
             break if s.empty?
             result << s
diff --git a/test/net/ftp/test_buffered_socket.rb b/test/net/ftp/test_buffered_socket.rb
index 3cc46fa555..875c53f4e0 100644
--- a/test/net/ftp/test_buffered_socket.rb
+++ b/test/net/ftp/test_buffered_socket.rb
@@ -33,6 +33,12 @@ class BufferedSocketTest < Test::Unit::TestCase
     assert_equal("bar", sock.gets)
   end
 
+  def test_read_nil
+    sock = create_buffered_socket("foo\nbar")
+    assert_equal("foo\nbar", sock.read)
+    assert_equal("", sock.read)
+  end
+
   private
 
   def create_buffered_socket(s)
diff --git a/version.h b/version.h
index 4d85aff660..333cc77210 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.3.7"
 #define RUBY_RELEASE_DATE "2018-03-28"
-#define RUBY_PATCHLEVEL 439
+#define RUBY_PATCHLEVEL 440
 
 #define RUBY_RELEASE_YEAR 2018
 #define RUBY_RELEASE_MONTH 3