stringio.c: padding in ungetbyte

* ext/stringio/stringio.c (strio_ungetbyte): pad with \000 when
  the current position is after the end.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53181 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 30 insertions, 0 deletions

diff --git a/test/stringio/test_stringio.rb b/test/stringio/test_stringio.rb
index af6efc684e..7b99d62f51 100644
--- a/test/stringio/test_stringio.rb
+++ b/test/stringio/test_stringio.rb
@@ -362,6 +362,11 @@ class TestStringIO < Test::Unit::TestCase
     t.ungetbyte("\xe7")
     t.ungetbyte("\xe7\xb4\x85")
     assert_equal("\u7d05\u7389bar\n", t.gets)
+    assert_equal("q\u7d05\u7389bar\n", s)
+    t.pos = 1
+    t.ungetbyte("\u{30eb 30d3 30fc}")
+    assert_equal(0, t.pos)
+    assert_equal("\u{30eb 30d3 30fc}\u7d05\u7389bar\n", s)
   end
 
   def test_ungetc
@@ -582,6 +587,31 @@ class TestStringIO < Test::Unit::TestCase
     assert_equal("b""\0""a", s.string)
   end
 
+  def test_ungetbyte_pos
+    b = '\\b00010001 \\B00010001 \\b1 \\B1 \\b000100011'
+    s = StringIO.new( b )
+    expected_pos = 0
+    while n = s.getbyte
+      assert_equal( expected_pos + 1, s.pos )
+
+      s.ungetbyte( n )
+      assert_equal( expected_pos, s.pos )
+      assert_equal( n, s.getbyte )
+
+      expected_pos += 1
+    end
+  end
+
+  def test_ungetbyte_padding
+    s = StringIO.new()
+    s.pos = 2
+    s.ungetbyte("a".ord)
+    assert_equal("\0""a", s.string)
+    s.pos = 0
+    s.ungetbyte("b".ord)
+    assert_equal("b""\0""a", s.string)
+  end
+
   def test_frozen
     s = StringIO.new
     s.freeze