* fork.cc (fork): Eliminate superfluous call to getuid().

* security.h: New define `NO_SID'. Remove declarations of functions
        moved to methods into class cygsid.
        (class cygsid): Declare new methods `getfromstr', `get_sid',
        `getfrompw', `getfromgr', `get_rid', `get_uid', `get_gid', `string'
        and new constructors and operators =, == and !=.
        Declare new global cygsids `well_known_XXX_sid' substituting the
        corresponding `get_XXX_sid' functions. Remove declarations of
        these functions.
        * sec_helper.cc (well_known_admin_sid): New global variable.
        (well_known_system_sid): Ditto
        (well_known_creator_owner_sid): Ditto
        (well_known_world_sid): Ditto
        (cygsid::string): New method, substituting `convert_sid_to_string_sid'.
        (cygsid::get_sid): New method, substituting `get_sid'.
        (cygsid::getfromstr): New method, substituting
        `convert_string_sid_to_sid'.
        (cygsid::getfrompw): New method, substituting `get_pw_sid'.
        (cygsid::getfromgr): New method, substituting `get_gr_sid'.
        (cygsid::get_id): New method, substituting `get_id_from_sid'.
        (get_admin_sid): Eliminated.
        (get_system_sid): Ditto.
        (get_creator_owner_sid): Ditto.
        (get_world_sid): Ditto.
        * grp.cc: Use new cygsid methods and well known sids throughout.
        * registry.cc: Ditto.
        * sec_acl.cc: Ditto.
        * security.cc: Ditto.
        * shared.cc: Ditto.
        * syscalls.cc (seteuid): Ditto. Eliminate redundant conditional.
        * uinfo.cc (internal_getlogin): Ditto.
        * spawn.cc (spawn_guts) Revert previous patch.

winsup/cygwin/shared.cc

@@ -249,9 +249,9 @@ sec_user (PVOID sa_buf, PSID sid2, BOOL inherit)
   size_t acl_len = sizeof (ACL)
 		   + 4 * (sizeof (ACCESS_ALLOWED_ACE) - sizeof (DWORD))
 		   + GetLengthSid (sid)
-		   + GetLengthSid (get_admin_sid ())
-		   + GetLengthSid (get_system_sid ())
-		   + GetLengthSid (get_creator_owner_sid ());
+		   + GetLengthSid (well_known_admin_sid)
+		   + GetLengthSid (well_known_system_sid)
+		   + GetLengthSid (well_known_creator_owner_sid);
   if (sid2)
     acl_len += sizeof (ACCESS_ALLOWED_ACE) - sizeof (DWORD)
 	       + GetLengthSid (sid2);
@@ -266,17 +266,17 @@ sec_user (PVOID sa_buf, PSID sid2, BOOL inherit)
 
   if (! AddAccessAllowedAce (acl, ACL_REVISION,
 			     SPECIFIC_RIGHTS_ALL | STANDARD_RIGHTS_ALL,
-			     get_admin_sid ()))
+			     well_known_admin_sid))
     debug_printf ("AddAccessAllowedAce(admin) %E");
 
   if (! AddAccessAllowedAce (acl, ACL_REVISION,
 			     SPECIFIC_RIGHTS_ALL | STANDARD_RIGHTS_ALL,
-			     get_system_sid ()))
+			     well_known_system_sid))
     debug_printf ("AddAccessAllowedAce(system) %E");
 
   if (! AddAccessAllowedAce (acl, ACL_REVISION,
 			     SPECIFIC_RIGHTS_ALL | STANDARD_RIGHTS_ALL,
-			     get_creator_owner_sid ()))
+			     well_known_creator_owner_sid))
     debug_printf ("AddAccessAllowedAce(creator_owner) %E");
 
   if (sid2)