Document File.{setuid?,setgid?,sticky?} support for IO objects [Bug #13972]

* file.c (rb_file_setuid_p): rdoc for IO object support
  (rb_file_sgid_p): ditto (rb_file_sticky_p): ditto
* NEWS: inform users of new feature
* test/file/test_file_exhaustive.rb (io_open): wrapper for bare IO
  object (test_suid): test for bare IO support (test_sgid): ditto
  (test_sticky): ditto

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65235 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 26 insertions, 3 deletions

diff --git a/file.c b/file.c
index 66f62024d8..3ee966cec2 100644
--- a/file.c
+++ b/file.c
@@ -1948,6 +1948,8 @@ check3rdbyte(VALUE fname, int mode)
  *   File.setuid?(file_name)   ->  true or false
  *
  * Returns <code>true</code> if the named file has the setuid bit set.
+ *
+ * _file_name_ can be an IO object.
  */
 
 static VALUE
@@ -1965,6 +1967,8 @@ rb_file_suid_p(VALUE obj, VALUE fname)
  *   File.setgid?(file_name)   ->  true or false
  *
  * Returns <code>true</code> if the named file has the setgid bit set.
+ *
+ * _file_name_ can be an IO object.
  */
 
 static VALUE
@@ -1982,6 +1986,8 @@ rb_file_sgid_p(VALUE obj, VALUE fname)
  *   File.sticky?(file_name)   ->  true or false
  *
  * Returns <code>true</code> if the named file has the sticky bit set.
+ *
+ * _file_name_ can be an IO object.
  */
 
 static VALUE
diff --git a/test/ruby/test_file_exhaustive.rb b/test/ruby/test_file_exhaustive.rb
index 817c3580d1..28a3007fe5 100644
--- a/test/ruby/test_file_exhaustive.rb
+++ b/test/ruby/test_file_exhaustive.rb
@@ -495,22 +495,39 @@ class TestFileExhaustive < Test::Unit::TestCase
     assert_file.grpowned?(utf8_file)
   end if POSIX
 
+  def io_open(file_name)
+    # avoid File.open since we do not want #to_path
+    io = IO.for_fd(IO.sysopen(file_name))
+    yield io
+  ensure
+    io&.close
+  end
+
   def test_suid
     assert_file.not_setuid?(regular_file)
     assert_file.not_setuid?(utf8_file)
-    assert_file.setuid?(suidfile) if suidfile
+    if suidfile
+      assert_file.setuid?(suidfile)
+      io_open(suidfile) { |io| assert_file.setuid?(io) }
+    end
   end
 
   def test_sgid
     assert_file.not_setgid?(regular_file)
     assert_file.not_setgid?(utf8_file)
-    assert_file.setgid?(sgidfile) if sgidfile
+    if sgidfile
+      assert_file.setgid?(sgidfile)
+      io_open(sgidfile) { |io| assert_file.setgid?(io) }
+    end
   end
 
   def test_sticky
     assert_file.not_sticky?(regular_file)
     assert_file.not_sticky?(utf8_file)
-    assert_file.sticky?(stickyfile) if stickyfile
+    if stickyfile
+      assert_file.sticky?(stickyfile)
+      io_open(stickyfile) { |io| assert_file.sticky?(io) }
+    end
   end
 
   def test_path_identical_p