kc3-lang/gnulib/lib/fts-cycle.c

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• Hash : 7b089321
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  Date : 2025-01-01T09:24:36
  

  maint: run 'make update-copyright'
  

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• lib/fts-cycle.c

• /* Detect cycles in file tree walks.
  
     Copyright (C) 2003-2006, 2009-2025 Free Software Foundation, Inc.
  
     Written by Jim Meyering.
  
     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 3 of the License, 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, see <https://www.gnu.org/licenses/>.  */
  
  #include "cycle-check.h"
  #include "hash.h"
  
  /* Use each of these to map a device/inode pair to an FTSENT.  */
  struct Active_dir
  {
    dev_t dev;
    ino_t ino;
    FTSENT *fts_ent;
  };
  
  static bool
  AD_compare (void const *x, void const *y)
  {
    struct Active_dir const *ax = x;
    struct Active_dir const *ay = y;
    return ax->ino == ay->ino
        && ax->dev == ay->dev;
  }
  
  static size_t
  AD_hash (void const *x, size_t table_size)
  {
    struct Active_dir const *ax = x;
    return (uintmax_t) ax->ino % table_size;
  }
  
  /* Set up the cycle-detection machinery.  */
  
  static bool
  setup_dir (FTS *fts)
  {
    if (fts->fts_options & (FTS_TIGHT_CYCLE_CHECK | FTS_LOGICAL))
      {
        enum { HT_INITIAL_SIZE = 31 };
        fts->fts_cycle.ht = hash_initialize (HT_INITIAL_SIZE, NULL, AD_hash,
                                             AD_compare, free);
        if (! fts->fts_cycle.ht)
          return false;
      }
    else
      {
        fts->fts_cycle.state = malloc (sizeof *fts->fts_cycle.state);
        if (! fts->fts_cycle.state)
          return false;
        cycle_check_init (fts->fts_cycle.state);
      }
  
    return true;
  }
  
  /* Enter a directory during a file tree walk.  */
  
  static bool
  enter_dir (FTS *fts, FTSENT *ent)
  {
    if (fts->fts_options & (FTS_TIGHT_CYCLE_CHECK | FTS_LOGICAL))
      {
        struct stat const *st = ent->fts_statp;
        struct Active_dir *ad = malloc (sizeof *ad);
        struct Active_dir *ad_from_table;
  
        if (!ad)
          return false;
  
        ad->dev = st->st_dev;
        ad->ino = st->st_ino;
        ad->fts_ent = ent;
  
        /* See if we've already encountered this directory.
           This can happen when following symlinks as well as
           with a corrupted directory hierarchy. */
        ad_from_table = hash_insert (fts->fts_cycle.ht, ad);
  
        if (ad_from_table != ad)
          {
            free (ad);
            if (!ad_from_table)
              return false;
  
            /* There was an entry with matching dev/inode already in the table.
               Record the fact that we've found a cycle.  */
            ent->fts_cycle = ad_from_table->fts_ent;
            ent->fts_info = FTS_DC;
          }
      }
    else
      {
        if (cycle_check (fts->fts_cycle.state, ent->fts_statp))
          {
            /* FIXME: setting fts_cycle like this isn't proper.
               To do what the documentation requires, we'd have to
               go around the cycle again and find the right entry.
               But no callers in coreutils use the fts_cycle member. */
            ent->fts_cycle = ent;
            ent->fts_info = FTS_DC;
          }
      }
  
    return true;
  }
  
  /* Leave a directory during a file tree walk.  */
  
  static void
  leave_dir (FTS *fts, FTSENT *ent)
  {
    struct stat const *st = ent->fts_statp;
    if (fts->fts_options & (FTS_TIGHT_CYCLE_CHECK | FTS_LOGICAL))
      {
        struct Active_dir obj;
        void *found;
        obj.dev = st->st_dev;
        obj.ino = st->st_ino;
        found = hash_remove (fts->fts_cycle.ht, &obj);
        if (!found)
          abort ();
        free (found);
      }
    else
      {
        FTSENT *parent = ent->fts_parent;
        if (parent != NULL && 0 <= parent->fts_level)
          CYCLE_CHECK_REFLECT_CHDIR_UP (fts->fts_cycle.state,
                                        *(parent->fts_statp), *st);
      }
  }
  
  /* Free any memory used for cycle detection.  */
  
  static void
  free_dir (FTS *sp)
  {
    if (sp->fts_options & (FTS_TIGHT_CYCLE_CHECK | FTS_LOGICAL))
      {
        if (sp->fts_cycle.ht)
          hash_free (sp->fts_cycle.ht);
      }
    else
      free (sp->fts_cycle.state);
  }
  

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