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, 9 insertions, 2 deletions

diff --git a/file.c b/file.c
index 46593e0110..02ec141fb4 100644
--- a/file.c
+++ b/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));
 }