1  /* help detect directory cycles efficiently
       2  
       3     Copyright (C) 2003-2004, 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 Jim Meyering */
      19  
      20  #ifndef CYCLE_CHECK_H
      21  # define CYCLE_CHECK_H 1
      22  
      23  # include <stdint.h>
      24  # include "dev-ino.h"
      25  # include "same-inode.h"
      26  
      27  struct cycle_check_state
      28  {
      29    struct dev_ino dev_ino;
      30    uintmax_t chdir_counter;
      31    int magic;
      32  };
      33  
      34  void cycle_check_init (struct cycle_check_state *state);
      35  bool cycle_check (struct cycle_check_state *state, struct stat const *sb);
      36  
      37  # define CYCLE_CHECK_REFLECT_CHDIR_UP(State, SB_dir, SB_subdir) \
      38    do                                                            \
      39      {                                                           \
      40        /* You must call cycle_check at least once before using this macro.  */ \
      41        if ((State)->chdir_counter == 0)                          \
      42          abort ();                                               \
      43        if (SAME_INODE ((State)->dev_ino, SB_subdir))             \
      44          {                                                       \
      45            (State)->dev_ino.st_dev = (SB_dir).st_dev;            \
      46            (State)->dev_ino.st_ino = (SB_dir).st_ino;            \
      47          }                                                       \
      48      }                                                           \
      49    while (0)
      50  
      51  #endif