1  /* unlinkdir.c - determine whether we can unlink directories
       2  
       3     Copyright (C) 2005-2006, 2009-2023 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