* win32/win32.c (rb_w32_seekdir): should not segfault even if passed

the location which rb_w32_telldir didn't return. (and should change
  `bits' position) [ruby-core:7035]

* win32/dir.h: ditto. (stores `loc' instead of `bitpos')

* test/ruby/test_dir.rb: added.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@9782 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_dir.rb

@@ -0,0 +1,42 @@
+require 'test/unit'
+
+require 'tmpdir'
+require 'fileutils'
+
+class TestDir < Test::Unit::TestCase
+
+  ROOT = File.join(Dir.tmpdir, "__test_dir__#{$$}")
+
+  def setup
+    Dir.mkdir(ROOT)
+    for i in ?a..?z
+      if i % 2 == 0
+        FileUtils.touch(File.join(ROOT, i.chr))
+      else
+        FileUtils.mkdir(File.join(ROOT, i.chr))
+      end
+    end
+  end
+
+  def teardown
+    FileUtils.rm_rf ROOT if File.directory?(ROOT)
+  end
+
+  def test_seek
+    dir = Dir.open(ROOT)
+    begin
+      cache = []
+      loop do
+        pos = dir.tell
+        break unless name = dir.read
+        cache << [pos, name]
+      end
+      for x in cache.sort_by {|x| x[0] % 3 } # shuffle
+        dir.seek(x[0])
+        assert_equal(x[1], dir.read)
+      end
+    ensure
+      dir.close
+    end
+  end
+end