* io.c (io_unread): fix IO#pos with mode 'r' bug on Windows.

  If the end of reading buffer is CR, io_unread() needs to unread one
  more byte.
  [ruby-core:44874] [Bug #6401]

* test/ruby/test_io_m17n.rb (TestIO_M17N#test_pos_with_buffer_end_cr):
  add a test for above.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35594 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 32 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 134ed862b0..e68a7c30bf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+Tue May  8 20:44:46 2012  Hiroshi Shirosaki  <h.shirosaki@gmail.com>
+
+	* io.c (io_unread): fix IO#pos with mode 'r' bug on Windows.
+	  If the end of reading buffer is CR, io_unread() needs to unread one
+	  more byte.
+	  [ruby-core:44874] [Bug #6401]
+
+	* test/ruby/test_io_m17n.rb (TestIO_M17N#test_pos_with_buffer_end_cr):
+	  add a test for above.
+
 Tue May  8 13:38:17 2012  Ayumu AIZAWA  <ayumu.aizawa@gmail.com>
 
 	* ext/date/date_core.c: improving introduction in Date/DateTime
diff --git a/io.c b/io.c
index c4b7f128e0..5997c29611 100644
--- a/io.c
+++ b/io.c
@@ -457,6 +457,12 @@ io_unread(rb_io_t *fptr)
     /* add extra offset for removed '\r' in rbuf */
     extra_max = (long)(pos - fptr->rbuf.len);
     p = fptr->rbuf.ptr + fptr->rbuf.off;
+
+    /* if the end of rbuf is '\r', rbuf doesn't have '\r' within rbuf.len */
+    if (*(fptr->rbuf.ptr + fptr->rbuf.capa - 1) == '\r') {
+	newlines++;
+    }
+
     for (i = 0; i < fptr->rbuf.len; i++) {
 	if (*p == '\n') newlines++;
 	if (extra_max == newlines) break;
diff --git a/test/ruby/test_io_m17n.rb b/test/ruby/test_io_m17n.rb
index 719214d491..b6358e0d92 100644
--- a/test/ruby/test_io_m17n.rb
+++ b/test/ruby/test_io_m17n.rb
@@ -2432,6 +2432,22 @@ EOT
     }
   end if /mswin|mingw/ =~ RUBY_PLATFORM
 
+  def test_pos_with_buffer_end_cr
+    bug6401 = '[ruby-core:44874]'
+    with_tmpdir {
+      # Read buffer size is 8191. This generates '\r' at 8191.
+      lines = ["X" * 8187, "X"]
+      generate_file("tmp", lines.join("\r\n") + "\r\n")
+
+      open("tmp", "r") do |f|
+        lines.each do |line|
+          f.pos
+          assert_equal(line, f.readline.chomp, bug6401)
+        end
+      end
+    }
+  end if /mswin|mingw/ =~ RUBY_PLATFORM
+
   def test_read_crlf_and_eof
     bug6271 = '[ruby-core:44189]'
     with_tmpdir {