zlib: fix Gzip{Writer,Reader}.new fails with a O_TMPFILE file

ext/zlib/zlib.c

@@ -3520,6 +3520,16 @@ rb_gzfile_path(VALUE obj)
     return gz->path;
 }
 
+static VALUE
+gzfile_initialize_path_partial(VALUE obj)
+{
+	struct gzfile* gz;
+	TypedData_Get_Struct(obj, struct gzfile, &gzfile_data_type, gz);
+	gz->path = rb_funcall(gz->io, id_path, 0);
+	rb_define_singleton_method(obj, "path", rb_gzfile_path, 0);
+	return Qnil;
+}
+
 static void
 rb_gzfile_ecopts(struct gzfile *gz, VALUE opts)
 {
@@ -3628,8 +3638,8 @@ rb_gzwriter_initialize(int argc, VALUE *argv, VALUE obj)
     rb_gzfile_ecopts(gz, opt);
 
     if (rb_respond_to(io, id_path)) {
-	gz->path = rb_funcall(gz->io, id_path, 0);
+	/* File#path may raise IOError in case when a path is unavailable */
-	rb_define_singleton_method(obj, "path", rb_gzfile_path, 0);
+	rb_rescue2(gzfile_initialize_path_partial, obj, NULL, Qnil, rb_eIOError, (VALUE)0);
     }
 
     return obj;
@@ -3890,8 +3900,8 @@ rb_gzreader_initialize(int argc, VALUE *argv, VALUE obj)
     rb_gzfile_ecopts(gz, opt);
 
     if (rb_respond_to(io, id_path)) {
-	gz->path = rb_funcall(gz->io, id_path, 0);
+	/* File#path may raise IOError in case when a path is unavailable */
-	rb_define_singleton_method(obj, "path", rb_gzfile_path, 0);
+	rb_rescue2(gzfile_initialize_path_partial, obj, NULL, Qnil, rb_eIOError, (VALUE)0);
     }
 
     return obj;

test/zlib/test_zlib.rb

@@ -3,6 +3,7 @@
 require 'test/unit'
 require 'stringio'
 require 'tempfile'
+require 'tmpdir'
 
 begin
   require 'zlib'
@@ -722,6 +723,26 @@ if defined? Zlib
         gz.close
       }
     end
+
+    if defined? File::TMPFILE
+      def test_path_tmpfile
+        sio = StringIO.new("".dup, 'w')
+        gz = Zlib::GzipWriter.new(sio)
+        gz.write "hi"
+        gz.close
+
+        File.open(Dir.mktmpdir, File::RDWR | File::TMPFILE) do |io|
+          io.write sio.string
+          io.rewind
+
+          gz = Zlib::GzipWriter.new(io)
+          assert_raise(NoMethodError) { gz.path }
+
+          gz = Zlib::GzipReader.new(io)
+          assert_raise(NoMethodError) { gz.path }
+        end
+      end
+    end
   end
 
   class TestZlibGzipReader < Test::Unit::TestCase