Fix tests for CVE-2018-6914

Since the current working directory is not involved in `Tempfile`
and `Dir.mktmpdir` (except for the last resort), it is incorrect
to derive the traversal path from it.  Also, since the rubyspec
temporary directory is created under the build directory, this is
not involved in the target method.  Fixed sporadic errors in
test-spec.

1 files changed, 27 insertions, 37 deletions

diff --git a/test/test_tempfile.rb b/test/test_tempfile.rb
index 8fcba3aea8..7c911a1bf7 100644
--- a/test/test_tempfile.rb
+++ b/test/test_tempfile.rb
@@ -374,53 +374,43 @@ puts Tempfile.new('foo').path
     assert_file.not_exist?(path)
   end
 
-  TRAVERSAL_PATH = Array.new(Dir.pwd.split('/').count, '..').join('/') + Dir.pwd + '/'
-
   def test_open_traversal_dir
-    expect = Dir.glob(TRAVERSAL_PATH + '*').count
-    t = Tempfile.open([TRAVERSAL_PATH, 'foo'])
-    actual = Dir.glob(TRAVERSAL_PATH + '*').count
-    assert_equal expect, actual
-  rescue Errno::EINVAL
-    if /mswin|mingw/ =~ RUBY_PLATFORM
-      assert "ok"
-    else
-      raise $!
+    assert_mktmpdir_traversal do |traversal_path|
+      t = Tempfile.open([traversal_path, 'foo'])
+      t.path
+    ensure
+      t&.close!
     end
-  ensure
-    t&.close!
   end
 
   def test_new_traversal_dir
-    expect = Dir.glob(TRAVERSAL_PATH + '*').count
-    t = Tempfile.new(TRAVERSAL_PATH + 'foo')
-    actual = Dir.glob(TRAVERSAL_PATH + '*').count
-    assert_equal expect, actual
-  rescue Errno::EINVAL
-    if /mswin|mingw/ =~ RUBY_PLATFORM
-      assert "ok"
-    else
-      raise $!
+    assert_mktmpdir_traversal do |traversal_path|
+      t = Tempfile.new(traversal_path + 'foo')
+      t.path
+    ensure
+      t&.close!
     end
-  ensure
-    t&.close!
   end
 
   def test_create_traversal_dir
-    expect = Dir.glob(TRAVERSAL_PATH + '*').count
-    t = Tempfile.create(TRAVERSAL_PATH + 'foo')
-    actual = Dir.glob(TRAVERSAL_PATH + '*').count
-    assert_equal expect, actual
-  rescue Errno::EINVAL
-    if /mswin|mingw/ =~ RUBY_PLATFORM
-      assert "ok"
-    else
-      raise $!
+    assert_mktmpdir_traversal do |traversal_path|
+      t = Tempfile.create(traversal_path + 'foo')
+      t.path
+    ensure
+      if t
+        t.close
+        File.unlink(t.path)
+      end
     end
-  ensure
-    if t
-      t.close
-      File.unlink(t.path)
+  end
+
+  def assert_mktmpdir_traversal
+    Dir.mktmpdir do |target|
+      target = target.chomp('/') + '/'
+      traversal_path = target.sub(/\A\w:/, '') # for DOSISH
+      traversal_path = Array.new(target.count('/')-2, '..').join('/') + traversal_path
+      actual = yield traversal_path
+      assert_not_send([File.absolute_path(actual), :start_with?, target])
     end
   end
 end