1/* unlinkdir.c - determine (and maybe change) whether we can unlink directories 2 3 Copyright (C) 2005, 2006 Free Software Foundation, Inc. 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 2, or (at your option) 8 any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program; if not, write to the Free Software Foundation, 17 Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ 18 19/* Written by Paul Eggert and Jim Meyering. */ 20 21#include <config.h> 22 23#include "unlinkdir.h" 24 25#if HAVE_PRIV_H 26# include <priv.h> 27#endif 28#include <unistd.h> 29 30#if ! UNLINK_CANNOT_UNLINK_DIR 31 32/* Return true if we cannot unlink directories, false if we might be 33 able to unlink directories. If possible, tell the kernel we don't 34 want to be able to unlink directories, so that we can return true. */ 35 36bool 37cannot_unlink_dir (void) 38{ 39 static bool initialized; 40 static bool cannot; 41 42 if (! initialized) 43 { 44# if defined PRIV_EFFECTIVE && defined PRIV_SYS_LINKDIR 45 /* We might be able to unlink directories if we cannot 46 determine our privileges, or if we have the 47 PRIV_SYS_LINKDIR privilege and cannot delete it. */ 48 priv_set_t *pset = priv_allocset (); 49 if (pset) 50 { 51 cannot = 52 (getppriv (PRIV_EFFECTIVE, pset) == 0 53 && (! priv_ismember (pset, PRIV_SYS_LINKDIR) 54 || (priv_delset (pset, PRIV_SYS_LINKDIR) == 0 55 && setppriv (PRIV_SET, PRIV_EFFECTIVE, pset) == 0))); 56 priv_freeset (pset); 57 } 58# else 59 /* In traditional Unix, only root can unlink directories. */ 60 cannot = (geteuid () != 0); 61# endif 62 initialized = true; 63 } 64 65 return cannot; 66} 67 68#endif 69