File#path: Raise IOError when a file is O_TMPFILE

File#path for a file opened with O_TMPFILE has no meaning.

A filepath returned by this method isn't guarranteed about its accuracy,
but files opened with O_TMPFILE are known its recorded path has no
meaning. So let them not to return any pathname.

After a discussion in ruby-core, just returning Qnil makes guessing the
root cause difficult. Instead, this patch makes the method to raise an
error.

Other consideration is calling fnctl(2) on rb_file_path, but it adds a
overhead, and it's difficult to determine O_TMPFILE status  after fd has
been closed.

[Feature #13568]

* io.c(rb_file_open_generic): Set Qnil to fptr->pathv when opening a
  file using O_TMPFILE

* file.c(rb_file_path): Raise IOError when fptr->pathv is Qnil

* file.c(rb_file_path): [DOC] Update for the new behavior

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59704 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 12 insertions, 0 deletions

diff --git a/test/ruby/test_file.rb b/test/ruby/test_file.rb
index 58a4240391..bb366ce81f 100644
--- a/test/ruby/test_file.rb
+++ b/test/ruby/test_file.rb
@@ -468,4 +468,16 @@ class TestFile < Test::Unit::TestCase
       assert_file.not_exist?(path)
     end
   end
+
+  def test_open_tempfile_path
+    Dir.mktmpdir(__method__.to_s) do |tmpdir|
+      File.open(tmpdir, File::RDWR | File::TMPFILE) do |io|
+        io.write "foo"
+        io.flush
+        assert_equal 3, io.size
+        assert_raise(IOError) { io.path }
+      end
+    end
+  end if File::Constants.const_defined?(:TMPFILE)
+
 end