[ruby-dev:24870] StringIO#read(size, buf)

<URL:http://www.yo.rim.or.jp/~nov/d/?date=20041116#p03>
でStringIO#readの第二引数を与えると
いつでもStringIOの文字列の先頭から
読み込んでしまう問題が報告されています。

以下のような変更はどうでしょうか。

Index: ext/stringio/stringio.c
===================================================================
RCS file: /var/cvs/src/ruby/ext/stringio/stringio.c,v
retrieving revision 1.26.2.4
diff -u -r1.26.2.4 stringio.c
--- ext/stringio/stringio.c	6 Oct 2004 17:57:19 -0000	1.26.2.4
+++ ext/stringio/stringio.c	16 Nov 2004 07:50:24 -0000
@@ -889,7 +889,7 @@
 	long rest = RSTRING(ptr->string)->len - ptr->pos;
 	if (len > rest) len = rest;
 	rb_str_resize(str, len);
-	MEMCPY(RSTRING(str)->ptr, RSTRING(ptr->string)->ptr, char, len);
+	MEMCPY(RSTRING(str)->ptr, RSTRING(ptr->string)->ptr + ptr->pos, char,
len);
     }
     if (NIL_P(str)) {
 	if (!(ptr->flags & STRIO_EOF)) str = rb_str_new(0, 0);
Index: test/stringio/test_stringio.rb
===================================================================
RCS file: /var/cvs/src/ruby/test/stringio/test_stringio.rb,v
retrieving revision 1.4.2.2
diff -u -r1.4.2.2 test_stringio.rb
--- test/stringio/test_stringio.rb	8 Sep 2004 09:44:46 -0000	1.4.2.2
+++ test/stringio/test_stringio.rb	16 Nov 2004 07:50:24 -0000
@@ -30,4 +30,24 @@
     io.print "last"
     assert_equal("\0" * n + "last", io.string)
   end
+
+  def test_read
+    io = StringIO.new("0123456789")
+    buf = ""
+    io.read(2, buf)
+    io.read(2, buf)
+    assert_equal(4, io.pos)
+    assert_equal("23", buf)
+    buf << io.read(2)
+    buf << io.read(2)
+    assert_equal("234567", buf)
+    assert_equal(8, io.pos)
+
+    io.rewind
+    buf = ""
+    io.read(5, buf)
+    buf << io.read(5)
+    assert_equal("0123456789", buf)
+    assert_equal(10, io.pos)
+  end
 end

-- 
やまだあきら / akira yamada  <http://arika.org>