3 files changed, 31 insertions, 16 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index a35c51b8555..ff80763f351 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,12 @@
+2012-12-14  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Fix permissions bugs with setgid directories etc. (Bug#13125)
+        * dired.c (Ffile_attributes): Return t as the 9th attribute,
+        to mark it as a placeholder.  The old value was often wrong.
+        The only user of this attribute has been changed to use
+        file-ownership-preserved-p instead, with its new group arg.
+        * editfns.c (Fgroup_gid, Fgroup_real_gid): New functions.
+
 2012-12-14  Stefan Monnier  <monnier@iro.umontreal.ca>
 
         * xdisp.c (select_frame_for_redisplay, display_mode_lines):
diff --git a/src/dired.c b/src/dired.c
index 85af906c1da..1fda9e8b371 100644
--- a/src/dired.c
+++ b/src/dired.c
@@ -869,7 +869,7 @@ Elements of the attribute list are:
  7. Size in bytes.
   This is a floating point number if the size is too large for an integer.
  8. File modes, as a string of ten letters or dashes as in ls -l.
- 9. t if file's gid would change if file were deleted and recreated.
+ 9. An unspecified value, present only for backward compatibility.
 10. inode number.  If it is larger than what an Emacs integer can hold,
   this is of the form (HIGH . LOW): first the high bits, then the low 16 bits.
   If even HIGH is too large for an Emacs integer, this is instead of the form
@@ -891,10 +891,6 @@ so last access time will always be midnight of that day.  */)
   Lisp_Object values[12];
   Lisp_Object encoded;
   struct stat s;
-#ifdef BSD4_2
-  Lisp_Object dirname;
-  struct stat sdir;
-#endif /* BSD4_2 */
   int lstat_result;
 
   /* An array to hold the mode string generated by filemodestring,
@@ -974,17 +970,7 @@ so last access time will always be midnight of that day.  */)
 
   filemodestring (&s, modes);
   values[8] = make_string (modes, 10);
-#ifdef BSD4_2 /* file gid will be dir gid */
-  dirname = Ffile_name_directory (filename);
-  if (! NILP (dirname))
-    encoded = ENCODE_FILE (dirname);
-  if (! NILP (dirname) && stat (SDATA (encoded), &sdir) == 0)
-    values[9] = (sdir.st_gid != s.st_gid) ? Qt : Qnil;
-  else                                  /* if we can't tell, assume worst */
-    values[9] = Qt;
-#else                                   /* file gid will be egid */
-  values[9] = (s.st_gid != getegid ()) ? Qt : Qnil;
-#endif  /* not BSD4_2 */
+  values[9] = Qt;
   values[10] = INTEGER_TO_CONS (s.st_ino);
   values[11] = INTEGER_TO_CONS (s.st_dev);
 
diff --git a/src/editfns.c b/src/editfns.c
index eb909f73697..108c8b27187 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -1272,6 +1272,24 @@ Value is an integer or a float, depending on the value.  */)
   return make_fixnum_or_float (uid);
 }
 
+DEFUN ("group-gid", Fgroup_gid, Sgroup_gid, 0, 0, 0,
+       doc: /* Return the effective gid of Emacs.
+Value is an integer or a float, depending on the value.  */)
+  (void)
+{
+  gid_t egid = getegid ();
+  return make_fixnum_or_float (egid);
+}
+
+DEFUN ("group-real-gid", Fgroup_real_gid, Sgroup_real_gid, 0, 0, 0,
+       doc: /* Return the real gid of Emacs.
+Value is an integer or a float, depending on the value.  */)
+  (void)
+{
+  gid_t gid = getgid ();
+  return make_fixnum_or_float (gid);
+}
+
 DEFUN ("user-full-name", Fuser_full_name, Suser_full_name, 0, 1, 0,
        doc: /* Return the full name of the user logged in, as a string.
 If the full name corresponding to Emacs's userid is not known,
@@ -4899,6 +4917,8 @@ functions if all the text being accessed has this property.  */);
   defsubr (&Suser_real_login_name);
   defsubr (&Suser_uid);
   defsubr (&Suser_real_uid);
+  defsubr (&Sgroup_gid);
+  defsubr (&Sgroup_real_gid);
   defsubr (&Suser_full_name);
   defsubr (&Semacs_pid);
   defsubr (&Scurrent_time);