/* unlinkdir.c - determine (and maybe change) whether we can unlink directories Copyright (C) 2005, 2006 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ /* Written by Paul Eggert and Jim Meyering. */ #include <config.h> #include "unlinkdir.h" #if HAVE_PRIV_H # include <priv.h> #endif #include <unistd.h> #if ! UNLINK_CANNOT_UNLINK_DIR /* Return true if we cannot unlink directories, false if we might be able to unlink directories. If possible, tell the kernel we don't want to be able to unlink directories, so that we can return true. */ bool cannot_unlink_dir (void) { static bool initialized; static bool cannot; if (! initialized) { # if defined PRIV_EFFECTIVE && defined PRIV_SYS_LINKDIR /* We might be able to unlink directories if we cannot determine our privileges, or if we have the PRIV_SYS_LINKDIR privilege and cannot delete it. */ priv_set_t *pset = priv_allocset (); if (pset) { cannot = (getppriv (PRIV_EFFECTIVE, pset) == 0 && (! priv_ismember (pset, PRIV_SYS_LINKDIR) || (priv_delset (pset, PRIV_SYS_LINKDIR) == 0 && setppriv (PRIV_SET, PRIV_EFFECTIVE, pset) == 0))); priv_freeset (pset); } # else /* In traditional Unix, only root can unlink directories. */ cannot = (geteuid () != 0); # endif initialized = true; } return cannot; } #endif