lib/unlinkdir.c

   1 /* unlinkdir.c - determine whether we can unlink directories
   2
   3    Copyright (C) 2005-2006, 2009-2020 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 3 of the License, or
   8    (at your option) 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, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Paul Eggert, Jim Meyering, and David Bartley.  */
  19
  20 #include <config.h>
  21
  22 #include "unlinkdir.h"
  23 #include "priv-set.h"
  24 #include "root-uid.h"
  25 #include <unistd.h>
  26
  27 #if ! UNLINK_CANNOT_UNLINK_DIR
  28
  29 /* Return true if we cannot unlink directories, false if we might be
  30    able to unlink directories.  */
  31
  32 bool
  33 cannot_unlink_dir (void)
  34 {
  35   static bool initialized;
  36   static bool cannot;
  37
  38   if (! initialized)
  39     {
  40 # if defined PRIV_SYS_LINKDIR
  41       /* We might be able to unlink directories if we cannot
  42          determine our privileges, or if we have the
  43          PRIV_SYS_LINKDIR privilege.  */
  44       cannot = (priv_set_ismember (PRIV_SYS_LINKDIR) == 0);
  45 # else
  46       /* In traditional Unix, only root can unlink directories.  */
  47       cannot = (geteuid () != ROOT_UID);
  48 # endif
  49       initialized = true;
  50     }
  51
  52   return cannot;
  53 }
  54
  55 #endif