From 23488589b38f09a95e7ba61a72b12358ad6185cb Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Thu, 7 Mar 2019 05:11:46 +0000
Subject: io.c: chomp CR at the end of read buffer

* io.c (rb_io_getline_fast): chomp CR followed by LF but separated
  by the read buffer boundary.  [ruby-core:91707] [Bug #15642]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67188 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 io.c                 |  6 ++++++
 test/ruby/test_io.rb | 13 +++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/io.c b/io.c
index 348e001b0d..8cbe34706c 100644
--- a/io.c
+++ b/io.c
@@ -3310,6 +3310,12 @@ rb_io_getline_fast(rb_io_t *fptr, rb_encoding *enc, int chomp)
 		read_buffered_data(RSTRING_PTR(str)+len, pending - chomplen, fptr);
 		fptr->rbuf.off += chomplen;
 		fptr->rbuf.len -= chomplen;
+                if (pending == 1 && chomplen == 1 && len > 0) {
+                    if (RSTRING_PTR(str)[len-1] == '\r') {
+                        rb_str_resize(str, --len);
+                        break;
+                    }
+                }
 	    }
 	    len += pending - chomplen;
 	    if (cr != ENC_CODERANGE_BROKEN)
diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index c83dc1c30d..f646c41a69 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -233,6 +233,19 @@ class TestIO < Test::Unit::TestCase
       assert_nil r.gets
       r.close
     end)
+
+    (0..3).each do |i|
+      pipe(proc do |w|
+        w.write("a" * ((4096 << i) - 4), "\r\n" "a\r\n")
+        w.close
+      end,
+      proc do |r|
+        r.gets
+        assert_equal "a", r.gets(chomp: true)
+        assert_nil r.gets
+        r.close
+      end)
+    end
   end
 
   def test_gets_chomp_rs_nil
-- 
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