1 /* unlinkdir.c - determine (and maybe change) whether we can unlink directories
3 Copyright (C) 2005-2006, 2009 Free Software Foundation, Inc.
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 3 of the License, or
8 (at your option) any later version.
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.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
18 /* Written by Paul Eggert and Jim Meyering. */
22 #include "unlinkdir.h"
29 #if ! UNLINK_CANNOT_UNLINK_DIR
31 /* Return true if we cannot unlink directories, false if we might be
32 able to unlink directories. If possible, tell the kernel we don't
33 want to be able to unlink directories, so that we can return true.
35 Note: this function may modify the process privilege set, to remove
36 the PRIV_SYS_LINKDIR privilege, so is neither thread-safe, nor
37 appropriate for use in a library. */
40 cannot_unlink_dir (void)
42 static bool initialized;
47 # if defined PRIV_EFFECTIVE && defined PRIV_SYS_LINKDIR
48 /* We might be able to unlink directories if we cannot
49 determine our privileges, or if we have the
50 PRIV_SYS_LINKDIR privilege and cannot delete it. */
51 priv_set_t *pset = priv_allocset ();
55 (getppriv (PRIV_EFFECTIVE, pset) == 0
56 && (! priv_ismember (pset, PRIV_SYS_LINKDIR)
57 || (priv_delset (pset, PRIV_SYS_LINKDIR) == 0
58 && setppriv (PRIV_SET, PRIV_EFFECTIVE, pset) == 0)));
62 /* In traditional Unix, only root can unlink directories. */
63 cannot = (geteuid () != 0);