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

file.c

@@ -379,7 +379,10 @@ apply2files(void (*func)(const char *, VALUE, void *), int argc, VALUE *argv, vo
  *  not normalize the name.
  *
  *  The pathname may not point the file corresponding to <i>file</i>.
- *  e.g. file has been moved, deleted, or created with <code>File::TMPFILE</code> option.
+ *  For instance, pathname becomes inaccurate when file has been moved or deleted.
+ *
+ *  This method raises <code>IOError</code> for a <i>file</i> created using
+ *  <code>File::Constants::TMPFILE</code> because they don't have a pathname.
  *
  *     File.new("testfile").path               #=> "testfile"
  *     File.new("/tmp/../tmp/xxx", "w").path   #=> "/tmp/../tmp/xxx"
@@ -393,7 +396,11 @@ rb_file_path(VALUE obj)
 
     fptr = RFILE(rb_io_taint_check(obj))->fptr;
     rb_io_check_initialized(fptr);
-    if (NIL_P(fptr->pathv)) return Qnil;
+
+    if (NIL_P(fptr->pathv)) {
+        rb_raise(rb_eIOError, "File is unnamed (TMPFILE?)");
+    }
+
     return rb_obj_taint(rb_str_dup(fptr->pathv));
 }
 

io.c

@@ -5833,6 +5833,7 @@ static VALUE
 rb_file_open_generic(VALUE io, VALUE filename, int oflags, int fmode,
 		     const convconfig_t *convconfig, mode_t perm)
 {
+    VALUE pathv;
     rb_io_t *fptr;
     convconfig_t cc;
     if (!convconfig) {
@@ -5848,8 +5849,15 @@ rb_file_open_generic(VALUE io, VALUE filename, int oflags, int fmode,
     MakeOpenFile(io, fptr);
     fptr->mode = fmode;
     fptr->encs = *convconfig;
-    fptr->pathv = rb_str_new_frozen(filename);
-    fptr->fd = rb_sysopen(fptr->pathv, oflags, perm);
+    pathv = rb_str_new_frozen(filename);
+#ifdef O_TMPFILE
+    if (!(oflags & O_TMPFILE)) {
+        fptr->pathv = pathv;
+    }
+#else
+    fptr->pathv = pathv;
+#endif
+    fptr->fd = rb_sysopen(pathv, oflags, perm);
     io_check_tty(fptr);
     if (fmode & FMODE_SETENC_BY_BOM) io_set_encoding_by_bom(io);
 

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