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fts.c

/* Traverse a file hierarchy.

   Copyright (C) 2004, 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 Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

/*-
 * Copyright (c) 1990, 1993, 1994
 *    The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)fts.c   8.6 (Berkeley) 8/14/94";
#endif /* LIBC_SCCS and not lint */

#include "fts_.h"

#if HAVE_SYS_PARAM_H || defined _LIBC
# include <sys/param.h>
#endif
#ifdef _LIBC
# include <include/sys/stat.h>
#else
# include <sys/stat.h>
#endif
#include <fcntl.h>
#include <errno.h>
#include "dirfd.h"
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#if ! _LIBC
# include "lstat.h"
#endif

#if defined _LIBC
# include <dirent.h>
# define NAMLEN(dirent) _D_EXACT_NAMLEN (dirent)
#else
# if HAVE_DIRENT_H
#  include <dirent.h>
#  define NAMLEN(dirent) strlen ((dirent)->d_name)
# else
#  define dirent direct
#  define NAMLEN(dirent) (dirent)->d_namlen
#  if HAVE_SYS_NDIR_H
#   include <sys/ndir.h>
#  endif
#  if HAVE_SYS_DIR_H
#   include <sys/dir.h>
#  endif
#  if HAVE_NDIR_H
#   include <ndir.h>
#  endif
# endif
#endif

#ifdef _LIBC
# undef close
# define close __close
# undef closedir
# define closedir __closedir
# undef fchdir
# define fchdir __fchdir
# undef open
# define open __open
# undef opendir
# define opendir __opendir
# undef readdir
# define readdir __readdir
#else
# undef internal_function
# define internal_function /* empty */
#endif

#ifndef __set_errno
# define __set_errno(Val) errno = (Val)
#endif

#ifndef __attribute__
# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 8) || __STRICT_ANSI__
#  define __attribute__(x) /* empty */
# endif
#endif

#ifndef ATTRIBUTE_UNUSED
# define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
#endif


static FTSENT     *fts_alloc (FTS *, const char *, size_t) internal_function;
static FTSENT     *fts_build (FTS *, int) internal_function;
static void  fts_lfree (FTSENT *) internal_function;
static void  fts_load (FTS *, FTSENT *) internal_function;
static size_t      fts_maxarglen (char * const *) internal_function;
static void  fts_padjust (FTS *, FTSENT *) internal_function;
static bool  fts_palloc (FTS *, size_t) internal_function;
static FTSENT     *fts_sort (FTS *, FTSENT *, size_t) internal_function;
static unsigned short int fts_stat (FTS *, FTSENT *, bool) internal_function;
static int      fts_safe_changedir (FTS *, FTSENT *, int, const char *)
     internal_function;

#if _LGPL_PACKAGE
static bool enter_dir (FTS *fts, FTSENT *ent) { return true; }
static void leave_dir (FTS *fts, FTSENT *ent) {}
static bool setup_dir (FTS *fts) { return true; }
static void free_dir (FTS *fts) {}
#else
# include "fcntl--.h"
# include "fts-cycle.c"
#endif

#ifndef MAX
# define MAX(a,b) ((a) > (b) ? (a) : (b))
#endif

#ifndef SIZE_MAX
# define SIZE_MAX ((size_t) -1)
#endif

#ifndef O_DIRECTORY
# define O_DIRECTORY 0
#endif

#define ISDOT(a)  (a[0] == '.' && (!a[1] || (a[1] == '.' && !a[2])))

#define CLR(opt)  (sp->fts_options &= ~(opt))
#define ISSET(opt)      (sp->fts_options & (opt))
#define SET(opt)  (sp->fts_options |= (opt))

#define FCHDIR(sp, fd)  (!ISSET(FTS_NOCHDIR) && fchdir(fd))

/* fts_build flags */
#define BCHILD          1           /* fts_children */
#define BNAMES          2           /* fts_children, names only */
#define BREAD           3           /* fts_read */

#if FTS_DEBUG
# include <inttypes.h>
# include <stdint.h>
# include <stdio.h>
bool fts_debug = false;
# define Dprintf(x) do { if (fts_debug) printf x; } while (0)
#else
# define Dprintf(x)
#endif

#define LEAVE_DIR(Fts, Ent, Tag)                      \
  do                                            \
    {                                           \
      Dprintf (("  %s-leaving: %s\n", Tag, (Ent)->fts_path));     \
      leave_dir (Fts, Ent);                           \
    }                                           \
  while (false)

/* Open the directory DIR if possible, and return a file
   descriptor.  Return -1 and set errno on failure.  It doesn't matter
   whether the file descriptor has read or write access.  */

static int
internal_function
diropen (char const *dir)
{
  return open (dir, O_RDONLY | O_DIRECTORY | O_NOCTTY | O_NONBLOCK);
}

FTS *
fts_open (char * const *argv,
        register int options,
        int (*compar) (FTSENT const **, FTSENT const **))
{
      register FTS *sp;
      register FTSENT *p, *root;
      register size_t nitems;
      FTSENT *parent, *tmp = NULL;  /* pacify gcc */
      size_t len;

      /* Options check. */
      if (options & ~FTS_OPTIONMASK) {
            __set_errno (EINVAL);
            return (NULL);
      }

      /* Allocate/initialize the stream */
      if ((sp = malloc(sizeof(FTS))) == NULL)
            return (NULL);
      memset(sp, 0, sizeof(FTS));
      sp->fts_compar = compar;
      sp->fts_options = options;

      /* Logical walks turn on NOCHDIR; symbolic links are too hard. */
      if (ISSET(FTS_LOGICAL))
            SET(FTS_NOCHDIR);

      /*
       * Start out with 1K of file name space, and enough, in any case,
       * to hold the user's file names.
       */
#ifndef MAXPATHLEN
# define MAXPATHLEN 1024
#endif
      {
        size_t maxarglen = fts_maxarglen(argv);
        if (! fts_palloc(sp, MAX(maxarglen, MAXPATHLEN)))
              goto mem1;
      }

      /* Allocate/initialize root's parent. */
      if ((parent = fts_alloc(sp, "", 0)) == NULL)
            goto mem2;
      parent->fts_level = FTS_ROOTPARENTLEVEL;

      /* Allocate/initialize root(s). */
      for (root = NULL, nitems = 0; *argv != NULL; ++argv, ++nitems) {
            /* Don't allow zero-length file names. */
            if ((len = strlen(*argv)) == 0) {
                  __set_errno (ENOENT);
                  goto mem3;
            }

            if ((p = fts_alloc(sp, *argv, len)) == NULL)
                  goto mem3;
            p->fts_level = FTS_ROOTLEVEL;
            p->fts_parent = parent;
            p->fts_accpath = p->fts_name;
            p->fts_info = fts_stat(sp, p, ISSET(FTS_COMFOLLOW) != 0);

            /* Command-line "." and ".." are real directories. */
            if (p->fts_info == FTS_DOT)
                  p->fts_info = FTS_D;

            /*
             * If comparison routine supplied, traverse in sorted
             * order; otherwise traverse in the order specified.
             */
            if (compar) {
                  p->fts_link = root;
                  root = p;
            } else {
                  p->fts_link = NULL;
                  if (root == NULL)
                        tmp = root = p;
                  else {
                        tmp->fts_link = p;
                        tmp = p;
                  }
            }
      }
      if (compar && nitems > 1)
            root = fts_sort(sp, root, nitems);

      /*
       * Allocate a dummy pointer and make fts_read think that we've just
       * finished the node before the root(s); set p->fts_info to FTS_INIT
       * so that everything about the "current" node is ignored.
       */
      if ((sp->fts_cur = fts_alloc(sp, "", 0)) == NULL)
            goto mem3;
      sp->fts_cur->fts_link = root;
      sp->fts_cur->fts_info = FTS_INIT;
      if (! setup_dir (sp))
        goto mem3;

      /*
       * If using chdir(2), grab a file descriptor pointing to dot to ensure
       * that we can get back here; this could be avoided for some file names,
       * but almost certainly not worth the effort.  Slashes, symbolic links,
       * and ".." are all fairly nasty problems.  Note, if we can't get the
       * descriptor we run anyway, just more slowly.
       */
      if (!ISSET(FTS_NOCHDIR)
          && (sp->fts_rfd = diropen (".")) < 0)
            SET(FTS_NOCHDIR);

      return (sp);

mem3: fts_lfree(root);
      free(parent);
mem2: free(sp->fts_path);
mem1: free(sp);
      return (NULL);
}

static void
internal_function
fts_load (FTS *sp, register FTSENT *p)
{
      register size_t len;
      register char *cp;

      /*
       * Load the stream structure for the next traversal.  Since we don't
       * actually enter the directory until after the preorder visit, set
       * the fts_accpath field specially so the chdir gets done to the right
       * place and the user can access the first node.  From fts_open it's
       * known that the file name will fit.
       */
      len = p->fts_pathlen = p->fts_namelen;
      memmove(sp->fts_path, p->fts_name, len + 1);
      if ((cp = strrchr(p->fts_name, '/')) && (cp != p->fts_name || cp[1])) {
            len = strlen(++cp);
            memmove(p->fts_name, cp, len + 1);
            p->fts_namelen = len;
      }
      p->fts_accpath = p->fts_path = sp->fts_path;
      sp->fts_dev = p->fts_statp->st_dev;
}

int
fts_close (FTS *sp)
{
      register FTSENT *freep, *p;
      int saved_errno = 0;

      /*
       * This still works if we haven't read anything -- the dummy structure
       * points to the root list, so we step through to the end of the root
       * list which has a valid parent pointer.
       */
      if (sp->fts_cur) {
            for (p = sp->fts_cur; p->fts_level >= FTS_ROOTLEVEL;) {
                  freep = p;
                  p = p->fts_link != NULL ? p->fts_link : p->fts_parent;
                  free(freep);
            }
            free(p);
      }

      /* Free up child linked list, sort array, file name buffer. */
      if (sp->fts_child)
            fts_lfree(sp->fts_child);
      if (sp->fts_array)
            free(sp->fts_array);
      free(sp->fts_path);

      /* Return to original directory, save errno if necessary. */
      if (!ISSET(FTS_NOCHDIR)) {
            if (fchdir(sp->fts_rfd))
                  saved_errno = errno;
            (void)close(sp->fts_rfd);
      }

      free_dir (sp);

      /* Free up the stream pointer. */
      free(sp);

      /* Set errno and return. */
      if (saved_errno) {
            __set_errno (saved_errno);
            return (-1);
      }

      return (0);
}

/*
 * Special case of "/" at the end of the file name so that slashes aren't
 * appended which would cause file names to be written as "....//foo".
 */
#define NAPPEND(p)                                          \
      (p->fts_path[p->fts_pathlen - 1] == '/'                     \
          ? p->fts_pathlen - 1 : p->fts_pathlen)

FTSENT *
fts_read (register FTS *sp)
{
      register FTSENT *p, *tmp;
      register unsigned short int instr;
      register char *t;
      int saved_errno;

      /* If finished or unrecoverable error, return NULL. */
      if (sp->fts_cur == NULL || ISSET(FTS_STOP))
            return (NULL);

      /* Set current node pointer. */
      p = sp->fts_cur;

      /* Save and zero out user instructions. */
      instr = p->fts_instr;
      p->fts_instr = FTS_NOINSTR;

      /* Any type of file may be re-visited; re-stat and re-turn. */
      if (instr == FTS_AGAIN) {
            p->fts_info = fts_stat(sp, p, false);
            return (p);
      }
      Dprintf (("fts_read: p=%s\n",
              p->fts_info == FTS_INIT ? "" : p->fts_path));

      /*
       * Following a symlink -- SLNONE test allows application to see
       * SLNONE and recover.  If indirecting through a symlink, have
       * keep a pointer to current location.  If unable to get that
       * pointer, follow fails.
       */
      if (instr == FTS_FOLLOW &&
          (p->fts_info == FTS_SL || p->fts_info == FTS_SLNONE)) {
            p->fts_info = fts_stat(sp, p, true);
            if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {
                  if ((p->fts_symfd = diropen (".")) < 0) {
                        p->fts_errno = errno;
                        p->fts_info = FTS_ERR;
                  } else
                        p->fts_flags |= FTS_SYMFOLLOW;
            }
            goto check_for_dir;
      }

      /* Directory in pre-order. */
      if (p->fts_info == FTS_D) {
            /* If skipped or crossed mount point, do post-order visit. */
            if (instr == FTS_SKIP ||
                (ISSET(FTS_XDEV) && p->fts_statp->st_dev != sp->fts_dev)) {
                  if (p->fts_flags & FTS_SYMFOLLOW)
                        (void)close(p->fts_symfd);
                  if (sp->fts_child) {
                        fts_lfree(sp->fts_child);
                        sp->fts_child = NULL;
                  }
                  p->fts_info = FTS_DP;
                  LEAVE_DIR (sp, p, "1");
                  return (p);
            }

            /* Rebuild if only read the names and now traversing. */
            if (sp->fts_child != NULL && ISSET(FTS_NAMEONLY)) {
                  CLR(FTS_NAMEONLY);
                  fts_lfree(sp->fts_child);
                  sp->fts_child = NULL;
            }

            /*
             * Cd to the subdirectory.
             *
             * If have already read and now fail to chdir, whack the list
             * to make the names come out right, and set the parent errno
             * so the application will eventually get an error condition.
             * Set the FTS_DONTCHDIR flag so that when we logically change
             * directories back to the parent we don't do a chdir.
             *
             * If haven't read do so.  If the read fails, fts_build sets
             * FTS_STOP or the fts_info field of the node.
             */
            if (sp->fts_child != NULL) {
                  if (fts_safe_changedir(sp, p, -1, p->fts_accpath)) {
                        p->fts_errno = errno;
                        p->fts_flags |= FTS_DONTCHDIR;
                        for (p = sp->fts_child; p != NULL;
                             p = p->fts_link)
                              p->fts_accpath =
                                  p->fts_parent->fts_accpath;
                  }
            } else if ((sp->fts_child = fts_build(sp, BREAD)) == NULL) {
                  if (ISSET(FTS_STOP))
                        return (NULL);
                  /* If fts_build's call to fts_safe_changedir failed
                     because it was not able to fchdir into a
                     subdirectory, tell the caller.  */
                  if (p->fts_errno)
                        p->fts_info = FTS_ERR;
                  /* FIXME: see if this should be in an else block */
                  LEAVE_DIR (sp, p, "2");
                  return (p);
            }
            p = sp->fts_child;
            sp->fts_child = NULL;
            goto name;
      }

      /* Move to the next node on this level. */
next: tmp = p;
      if ((p = p->fts_link) != NULL) {
            free(tmp);

            /*
             * If reached the top, return to the original directory (or
             * the root of the tree), and load the file names for the next
             * root.
             */
            if (p->fts_level == FTS_ROOTLEVEL) {
                  if (FCHDIR(sp, sp->fts_rfd)) {
                        SET(FTS_STOP);
                        sp->fts_cur = p;
                        return (NULL);
                  }
                  fts_load(sp, p);
                  goto check_for_dir;
            }

            /*
             * User may have called fts_set on the node.  If skipped,
             * ignore.  If followed, get a file descriptor so we can
             * get back if necessary.
             */
            if (p->fts_instr == FTS_SKIP)
                  goto next;
            if (p->fts_instr == FTS_FOLLOW) {
                  p->fts_info = fts_stat(sp, p, true);
                  if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {
                        if ((p->fts_symfd = diropen (".")) < 0) {
                              p->fts_errno = errno;
                              p->fts_info = FTS_ERR;
                        } else
                              p->fts_flags |= FTS_SYMFOLLOW;
                  }
                  p->fts_instr = FTS_NOINSTR;
            }

name:       t = sp->fts_path + NAPPEND(p->fts_parent);
            *t++ = '/';
            memmove(t, p->fts_name, p->fts_namelen + 1);
check_for_dir:
            sp->fts_cur = p;
            if (p->fts_info == FTS_D)
              {
                Dprintf (("  %s-entering: %s\n", sp, p->fts_path));
                if (! enter_dir (sp, p))
                  {
                  __set_errno (ENOMEM);
                  return NULL;
                  }
              }
            return p;
      }

      /* Move up to the parent node. */
      p = tmp->fts_parent;
      free(tmp);

      if (p->fts_level == FTS_ROOTPARENTLEVEL) {
            /*
             * Done; free everything up and set errno to 0 so the user
             * can distinguish between error and EOF.
             */
            free(p);
            __set_errno (0);
            return (sp->fts_cur = NULL);
      }

      /* NUL terminate the file name.  */
      sp->fts_path[p->fts_pathlen] = '\0';

      /*
       * Return to the parent directory.  If at a root node or came through
       * a symlink, go back through the file descriptor.  Otherwise, cd up
       * one directory.
       */
      if (p->fts_level == FTS_ROOTLEVEL) {
            if (FCHDIR(sp, sp->fts_rfd)) {
                  p->fts_errno = errno;
                  SET(FTS_STOP);
            }
      } else if (p->fts_flags & FTS_SYMFOLLOW) {
            if (FCHDIR(sp, p->fts_symfd)) {
                  saved_errno = errno;
                  (void)close(p->fts_symfd);
                  __set_errno (saved_errno);
                  p->fts_errno = errno;
                  SET(FTS_STOP);
            }
            (void)close(p->fts_symfd);
      } else if (!(p->fts_flags & FTS_DONTCHDIR) &&
               fts_safe_changedir(sp, p->fts_parent, -1, "..")) {
            p->fts_errno = errno;
            SET(FTS_STOP);
      }
      p->fts_info = p->fts_errno ? FTS_ERR : FTS_DP;
      if (p->fts_errno == 0)
            LEAVE_DIR (sp, p, "3");
      sp->fts_cur = p;
      return ISSET(FTS_STOP) ? NULL : p;
}

/*
 * Fts_set takes the stream as an argument although it's not used in this
 * implementation; it would be necessary if anyone wanted to add global
 * semantics to fts using fts_set.  An error return is allowed for similar
 * reasons.
 */
/* ARGSUSED */
int
fts_set(FTS *sp ATTRIBUTE_UNUSED, FTSENT *p, int instr)
{
      if (instr != 0 && instr != FTS_AGAIN && instr != FTS_FOLLOW &&
          instr != FTS_NOINSTR && instr != FTS_SKIP) {
            __set_errno (EINVAL);
            return (1);
      }
      p->fts_instr = instr;
      return (0);
}

FTSENT *
fts_children (register FTS *sp, int instr)
{
      register FTSENT *p;
      int fd;

      if (instr != 0 && instr != FTS_NAMEONLY) {
            __set_errno (EINVAL);
            return (NULL);
      }

      /* Set current node pointer. */
      p = sp->fts_cur;

      /*
       * Errno set to 0 so user can distinguish empty directory from
       * an error.
       */
      __set_errno (0);

      /* Fatal errors stop here. */
      if (ISSET(FTS_STOP))
            return (NULL);

      /* Return logical hierarchy of user's arguments. */
      if (p->fts_info == FTS_INIT)
            return (p->fts_link);

      /*
       * If not a directory being visited in pre-order, stop here.  Could
       * allow FTS_DNR, assuming the user has fixed the problem, but the
       * same effect is available with FTS_AGAIN.
       */
      if (p->fts_info != FTS_D /* && p->fts_info != FTS_DNR */)
            return (NULL);

      /* Free up any previous child list. */
      if (sp->fts_child != NULL)
            fts_lfree(sp->fts_child);

      if (instr == FTS_NAMEONLY) {
            SET(FTS_NAMEONLY);
            instr = BNAMES;
      } else
            instr = BCHILD;

      /*
       * If using chdir on a relative file name and called BEFORE fts_read
       * does its chdir to the root of a traversal, we can lose -- we need to
       * chdir into the subdirectory, and we don't know where the current
       * directory is, so we can't get back so that the upcoming chdir by
       * fts_read will work.
       */
      if (p->fts_level != FTS_ROOTLEVEL || p->fts_accpath[0] == '/' ||
          ISSET(FTS_NOCHDIR))
            return (sp->fts_child = fts_build(sp, instr));

      if ((fd = diropen (".")) < 0)
            return (sp->fts_child = NULL);
      sp->fts_child = fts_build(sp, instr);
      if (fchdir(fd)) {
            int saved_errno = errno;
            (void)close(fd);
            __set_errno (saved_errno);
            return (NULL);
      }
      (void)close(fd);
      return (sp->fts_child);
}

/*
 * This is the tricky part -- do not casually change *anything* in here.  The
 * idea is to build the linked list of entries that are used by fts_children
 * and fts_read.  There are lots of special cases.
 *
 * The real slowdown in walking the tree is the stat calls.  If FTS_NOSTAT is
 * set and it's a physical walk (so that symbolic links can't be directories),
 * we can do things quickly.  First, if it's a 4.4BSD file system, the type
 * of the file is in the directory entry.  Otherwise, we assume that the number
 * of subdirectories in a node is equal to the number of links to the parent.
 * The former skips all stat calls.  The latter skips stat calls in any leaf
 * directories and for any files after the subdirectories in the directory have
 * been found, cutting the stat calls by about 2/3.
 */
static FTSENT *
internal_function
fts_build (register FTS *sp, int type)
{
      register struct dirent *dp;
      register FTSENT *p, *head;
      register size_t nitems;
      FTSENT *cur, *tail;
      DIR *dirp;
      void *oldaddr;
      int cderrno;
      int saved_errno;
      bool descend;
      bool doadjust;
      ptrdiff_t level;
      nlink_t nlinks;
      bool nostat;
      size_t len, maxlen, new_len;
      char *cp;

      /* Set current node pointer. */
      cur = sp->fts_cur;

      /*
       * Open the directory for reading.  If this fails, we're done.
       * If being called from fts_read, set the fts_info field.
       */
#if defined FTS_WHITEOUT && 0
      if (ISSET(FTS_WHITEOUT))
            oflag = DTF_NODUP|DTF_REWIND;
      else
            oflag = DTF_HIDEW|DTF_NODUP|DTF_REWIND;
#else
# define __opendir2(file, flag) opendir(file)
#endif
       if ((dirp = __opendir2(cur->fts_accpath, oflag)) == NULL) {
            if (type == BREAD) {
                  cur->fts_info = FTS_DNR;
                  cur->fts_errno = errno;
            }
            return (NULL);
      }

      /*
       * Nlinks is the number of possible entries of type directory in the
       * directory if we're cheating on stat calls, 0 if we're not doing
       * any stat calls at all, (nlink_t) -1 if we're statting everything.
       */
      if (type == BNAMES) {
            nlinks = 0;
            /* Be quiet about nostat, GCC. */
            nostat = false;
      } else if (ISSET(FTS_NOSTAT) && ISSET(FTS_PHYSICAL)) {
            nlinks = (cur->fts_statp->st_nlink
                    - (ISSET(FTS_SEEDOT) ? 0 : 2));
            nostat = true;
      } else {
            nlinks = -1;
            nostat = false;
      }

      /*
       * If we're going to need to stat anything or we want to descend
       * and stay in the directory, chdir.  If this fails we keep going,
       * but set a flag so we don't chdir after the post-order visit.
       * We won't be able to stat anything, but we can still return the
       * names themselves.  Note, that since fts_read won't be able to
       * chdir into the directory, it will have to return different file
       * names than before, i.e. "a/b" instead of "b".  Since the node
       * has already been visited in pre-order, have to wait until the
       * post-order visit to return the error.  There is a special case
       * here, if there was nothing to stat then it's not an error to
       * not be able to stat.  This is all fairly nasty.  If a program
       * needed sorted entries or stat information, they had better be
       * checking FTS_NS on the returned nodes.
       */
      cderrno = 0;
      if (nlinks || type == BREAD) {
            if (fts_safe_changedir(sp, cur, dirfd(dirp), NULL)) {
                  if (nlinks && type == BREAD)
                        cur->fts_errno = errno;
                  cur->fts_flags |= FTS_DONTCHDIR;
                  descend = false;
                  cderrno = errno;
                  closedir(dirp);
                  dirp = NULL;
            } else
                  descend = true;
      } else
            descend = false;

      /*
       * Figure out the max file name length that can be stored in the
       * current buffer -- the inner loop allocates more space as necessary.
       * We really wouldn't have to do the maxlen calculations here, we
       * could do them in fts_read before returning the name, but it's a
       * lot easier here since the length is part of the dirent structure.
       *
       * If not changing directories set a pointer so that can just append
       * each new component into the file name.
       */
      len = NAPPEND(cur);
      if (ISSET(FTS_NOCHDIR)) {
            cp = sp->fts_path + len;
            *cp++ = '/';
      } else {
            /* GCC, you're too verbose. */
            cp = NULL;
      }
      len++;
      maxlen = sp->fts_pathlen - len;

      level = cur->fts_level + 1;

      /* Read the directory, attaching each entry to the `link' pointer. */
      doadjust = false;
      for (head = tail = NULL, nitems = 0; dirp && (dp = readdir(dirp));) {
            if (!ISSET(FTS_SEEDOT) && ISDOT(dp->d_name))
                  continue;

            if ((p = fts_alloc(sp, dp->d_name, NAMLEN (dp))) == NULL)
                  goto mem1;
            if (NAMLEN (dp) >= maxlen) {/* include space for NUL */
                  oldaddr = sp->fts_path;
                  if (! fts_palloc(sp, NAMLEN (dp) + len + 1)) {
                        /*
                         * No more memory.  Save
                         * errno, free up the current structure and the
                         * structures already allocated.
                         */
mem1:                   saved_errno = errno;
                        if (p)
                              free(p);
                        fts_lfree(head);
                        closedir(dirp);
                        cur->fts_info = FTS_ERR;
                        SET(FTS_STOP);
                        __set_errno (saved_errno);
                        return (NULL);
                  }
                  /* Did realloc() change the pointer? */
                  if (oldaddr != sp->fts_path) {
                        doadjust = true;
                        if (ISSET(FTS_NOCHDIR))
                              cp = sp->fts_path + len;
                  }
                  maxlen = sp->fts_pathlen - len;
            }

            new_len = len + NAMLEN (dp);
            if (new_len < len) {
                  /*
                   * In the unlikely even that we would end up
                   * with a file name longer than SIZE_MAX, free up
                   * the current structure and the structures already
                   * allocated, then error out with ENAMETOOLONG.
                   */
                  free(p);
                  fts_lfree(head);
                  closedir(dirp);
                  cur->fts_info = FTS_ERR;
                  SET(FTS_STOP);
                  __set_errno (ENAMETOOLONG);
                  return (NULL);
            }
            p->fts_level = level;
            p->fts_parent = sp->fts_cur;
            p->fts_pathlen = new_len;

#if defined FTS_WHITEOUT && 0
            if (dp->d_type == DT_WHT)
                  p->fts_flags |= FTS_ISW;
#endif

            if (cderrno) {
                  if (nlinks) {
                        p->fts_info = FTS_NS;
                        p->fts_errno = cderrno;
                  } else
                        p->fts_info = FTS_NSOK;
                  p->fts_accpath = cur->fts_accpath;
            } else if (nlinks == 0
#if HAVE_STRUCT_DIRENT_D_TYPE
                     || (nostat &&
                         dp->d_type != DT_DIR && dp->d_type != DT_UNKNOWN)
#endif
                ) {
                  p->fts_accpath =
                      ISSET(FTS_NOCHDIR) ? p->fts_path : p->fts_name;
                  p->fts_info = FTS_NSOK;
            } else {
                  /* Build a file name for fts_stat to stat. */
                  if (ISSET(FTS_NOCHDIR)) {
                        p->fts_accpath = p->fts_path;
                        memmove(cp, p->fts_name, p->fts_namelen + 1);
                  } else
                        p->fts_accpath = p->fts_name;
                  /* Stat it. */
                  p->fts_info = fts_stat(sp, p, false);

                  /* Decrement link count if applicable. */
                  if (nlinks > 0 && (p->fts_info == FTS_D ||
                      p->fts_info == FTS_DC || p->fts_info == FTS_DOT))
                        nlinks -= nostat;
            }

            /* We walk in directory order so "ls -f" doesn't get upset. */
            p->fts_link = NULL;
            if (head == NULL)
                  head = tail = p;
            else {
                  tail->fts_link = p;
                  tail = p;
            }
            ++nitems;
      }
      if (dirp)
            closedir(dirp);

      /*
       * If realloc() changed the address of the file name, adjust the
       * addresses for the rest of the tree and the dir list.
       */
      if (doadjust)
            fts_padjust(sp, head);

      /*
       * If not changing directories, reset the file name back to original
       * state.
       */
      if (ISSET(FTS_NOCHDIR)) {
            if (len == sp->fts_pathlen || nitems == 0)
                  --cp;
            *cp = '\0';
      }

      /*
       * If descended after called from fts_children or after called from
       * fts_read and nothing found, get back.  At the root level we use
       * the saved fd; if one of fts_open()'s arguments is a relative name
       * to an empty directory, we wind up here with no other way back.  If
       * can't get back, we're done.
       */
      if (descend && (type == BCHILD || !nitems) &&
          (cur->fts_level == FTS_ROOTLEVEL ?
           FCHDIR(sp, sp->fts_rfd) :
           fts_safe_changedir(sp, cur->fts_parent, -1, ".."))) {
            cur->fts_info = FTS_ERR;
            SET(FTS_STOP);
            return (NULL);
      }

      /* If didn't find anything, return NULL. */
      if (!nitems) {
            if (type == BREAD)
                  cur->fts_info = FTS_DP;
            return (NULL);
      }

      /* Sort the entries. */
      if (sp->fts_compar && nitems > 1)
            head = fts_sort(sp, head, nitems);
      return (head);
}

#if FTS_DEBUG

/* Walk ->fts_parent links starting at E_CURR, until the root of the
   current hierarchy.  There should be a directory with dev/inode
   matching those of AD.  If not, print a lot of diagnostics.  */
static void
find_matching_ancestor (FTSENT const *e_curr, struct Active_dir const *ad)
{
  FTSENT const *ent;
  for (ent = e_curr; ent->fts_level >= FTS_ROOTLEVEL; ent = ent->fts_parent)
    {
      if (ad->ino == ent->fts_statp->st_ino
        && ad->dev == ent->fts_statp->st_dev)
      return;
    }
  printf ("ERROR: tree dir, %s, not active\n", ad->fts_ent->fts_accpath);
  printf ("active dirs:\n");
  for (ent = e_curr;
       ent->fts_level >= FTS_ROOTLEVEL; ent = ent->fts_parent)
    printf ("  %s(%"PRIuMAX"/%"PRIuMAX") to %s(%"PRIuMAX"/%"PRIuMAX")...\n",
          ad->fts_ent->fts_accpath,
          (uintmax_t) ad->dev,
          (uintmax_t) ad->ino,
          ent->fts_accpath,
          (uintmax_t) ent->fts_statp->st_dev,
          (uintmax_t) ent->fts_statp->st_ino);
}

void
fts_cross_check (FTS const *sp)
{
  FTSENT const *ent = sp->fts_cur;
  FTSENT const *t;
  if ( ! ISSET (FTS_TIGHT_CYCLE_CHECK))
    return;

  Dprintf (("fts-cross-check cur=%s\n", ent->fts_path));
  /* Make sure every parent dir is in the tree.  */
  for (t = ent->fts_parent; t->fts_level >= FTS_ROOTLEVEL; t = t->fts_parent)
    {
      struct Active_dir ad;
      ad.ino = t->fts_statp->st_ino;
      ad.dev = t->fts_statp->st_dev;
      if ( ! hash_lookup (sp->fts_cycle.ht, &ad))
      printf ("ERROR: active dir, %s, not in tree\n", t->fts_path);
    }

  /* Make sure every dir in the tree is an active dir.
     But ENT is not necessarily a directory.  If so, just skip this part. */
  if (ent->fts_parent->fts_level >= FTS_ROOTLEVEL
      && (ent->fts_info == FTS_DP
        || ent->fts_info == FTS_D))
    {
      struct Active_dir *ad;
      for (ad = hash_get_first (sp->fts_cycle.ht); ad != NULL;
         ad = hash_get_next (sp->fts_cycle.ht, ad))
      {
        find_matching_ancestor (ent, ad);
      }
    }
}
#endif

static unsigned short int
internal_function
fts_stat(FTS *sp, register FTSENT *p, bool follow)
{
      struct stat *sbp = p->fts_statp;
      int saved_errno;

#if defined FTS_WHITEOUT && 0
      /* check for whiteout */
      if (p->fts_flags & FTS_ISW) {
            memset(sbp, '\0', sizeof (*sbp));
            sbp->st_mode = S_IFWHT;
            return (FTS_W);
       }
#endif

      /*
       * If doing a logical walk, or application requested FTS_FOLLOW, do
       * a stat(2).  If that fails, check for a non-existent symlink.  If
       * fail, set the errno from the stat call.
       */
      if (ISSET(FTS_LOGICAL) || follow) {
            if (stat(p->fts_accpath, sbp)) {
                  saved_errno = errno;
                  if (errno == ENOENT
                      && lstat(p->fts_accpath, sbp) == 0) {
                        __set_errno (0);
                        return (FTS_SLNONE);
                  }
                  p->fts_errno = saved_errno;
                  goto err;
            }
      } else if (lstat(p->fts_accpath, sbp)) {
            p->fts_errno = errno;
err:        memset(sbp, 0, sizeof(struct stat));
            return (FTS_NS);
      }

      if (S_ISDIR(sbp->st_mode)) {
            if (ISDOT(p->fts_name))
                  return (FTS_DOT);

#if _LGPL_PACKAGE
            {
              /*
               * Cycle detection is done by brute force when the directory
               * is first encountered.  If the tree gets deep enough or the
               * number of symbolic links to directories is high enough,
               * something faster might be worthwhile.
               */
              FTSENT *t;

              for (t = p->fts_parent;
                   t->fts_level >= FTS_ROOTLEVEL; t = t->fts_parent)
                if (sbp->st_ino == t->fts_statp->st_ino
                  && sbp->st_dev == t->fts_statp->st_dev)
                  {
                  p->fts_cycle = t;
                  return (FTS_DC);
                  }
            }
#endif

            return (FTS_D);
      }
      if (S_ISLNK(sbp->st_mode))
            return (FTS_SL);
      if (S_ISREG(sbp->st_mode))
            return (FTS_F);
      return (FTS_DEFAULT);
}

static int
fts_compar (void const *a, void const *b)
{
  /* Convert A and B to the correct types, to pacify the compiler, and
     for portability to bizarre hosts where "void const *" and "FTSENT
     const **" differ in runtime representation.  The comparison
     function cannot modify *a and *b, but there is no compile-time
     check for this.  */
  FTSENT const **pa = (FTSENT const **) a;
  FTSENT const **pb = (FTSENT const **) b;
  return pa[0]->fts_fts->fts_compar (pa, pb);
}

static FTSENT *
internal_function
fts_sort (FTS *sp, FTSENT *head, register size_t nitems)
{
      register FTSENT **ap, *p;

      /* On most modern hosts, void * and FTSENT ** have the same
         run-time representation, and one can convert sp->fts_compar to
         the type qsort expects without problem.  Use the heuristic that
         this is OK if the two pointer types are the same size, and if
         converting FTSENT ** to long int is the same as converting
         FTSENT ** to void * and then to long int.  This heuristic isn't
         valid in general but we don't know of any counterexamples.  */
      FTSENT *dummy;
      int (*compare) (void const *, void const *) =
        ((sizeof &dummy == sizeof (void *)
          && (long int) &dummy == (long int) (void *) &dummy)
         ? (int (*) (void const *, void const *)) sp->fts_compar
         : fts_compar);

      /*
       * Construct an array of pointers to the structures and call qsort(3).
       * Reassemble the array in the order returned by qsort.  If unable to
       * sort for memory reasons, return the directory entries in their
       * current order.  Allocate enough space for the current needs plus
       * 40 so don't realloc one entry at a time.
       */
      if (nitems > sp->fts_nitems) {
            struct _ftsent **a;

            sp->fts_nitems = nitems + 40;
            if (SIZE_MAX / sizeof *a < sp->fts_nitems
                || ! (a = realloc (sp->fts_array,
                               sp->fts_nitems * sizeof *a))) {
                  free(sp->fts_array);
                  sp->fts_array = NULL;
                  sp->fts_nitems = 0;
                  return (head);
            }
            sp->fts_array = a;
      }
      for (ap = sp->fts_array, p = head; p; p = p->fts_link)
            *ap++ = p;
      qsort((void *)sp->fts_array, nitems, sizeof(FTSENT *), compare);
      for (head = *(ap = sp->fts_array); --nitems; ++ap)
            ap[0]->fts_link = ap[1];
      ap[0]->fts_link = NULL;
      return (head);
}

static FTSENT *
internal_function
fts_alloc (FTS *sp, const char *name, register size_t namelen)
{
      register FTSENT *p;
      size_t len;

      /*
       * The file name is a variable length array.  Allocate the FTSENT
       * structure and the file name in one chunk.
       */
      len = sizeof(FTSENT) + namelen;
      if ((p = malloc(len)) == NULL)
            return (NULL);

      /* Copy the name and guarantee NUL termination. */
      memmove(p->fts_name, name, namelen);
      p->fts_name[namelen] = '\0';

      p->fts_namelen = namelen;
      p->fts_fts = sp;
      p->fts_path = sp->fts_path;
      p->fts_errno = 0;
      p->fts_flags = 0;
      p->fts_instr = FTS_NOINSTR;
      p->fts_number = 0;
      p->fts_pointer = NULL;
      return (p);
}

static void
internal_function
fts_lfree (register FTSENT *head)
{
      register FTSENT *p;

      /* Free a linked list of structures. */
      while ((p = head)) {
            head = head->fts_link;
            free(p);
      }
}

/*
 * Allow essentially unlimited file name lengths; find, rm, ls should
 * all work on any tree.  Most systems will allow creation of file
 * names much longer than MAXPATHLEN, even though the kernel won't
 * resolve them.  Add the size (not just what's needed) plus 256 bytes
 * so don't realloc the file name 2 bytes at a time.
 */
static bool
internal_function
fts_palloc (FTS *sp, size_t more)
{
      char *p;
      size_t new_len = sp->fts_pathlen + more + 256;

      /*
       * See if fts_pathlen would overflow.
       */
      if (new_len < sp->fts_pathlen) {
            if (sp->fts_path) {
                  free(sp->fts_path);
                  sp->fts_path = NULL;
            }
            sp->fts_path = NULL;
            __set_errno (ENAMETOOLONG);
            return false;
      }
      sp->fts_pathlen = new_len;
      p = realloc(sp->fts_path, sp->fts_pathlen);
      if (p == NULL) {
            free(sp->fts_path);
            sp->fts_path = NULL;
            return false;
      }
      sp->fts_path = p;
      return true;
}

/*
 * When the file name is realloc'd, have to fix all of the pointers in
 *  structures already returned.
 */
static void
internal_function
fts_padjust (FTS *sp, FTSENT *head)
{
      FTSENT *p;
      char *addr = sp->fts_path;

#define ADJUST(p) do {                                      \
      if ((p)->fts_accpath != (p)->fts_name) {              \
            (p)->fts_accpath =                              \
                (char *)addr + ((p)->fts_accpath - (p)->fts_path);      \
      }                                               \
      (p)->fts_path = addr;                                 \
} while (0)
      /* Adjust the current set of children. */
      for (p = sp->fts_child; p; p = p->fts_link)
            ADJUST(p);

      /* Adjust the rest of the tree, including the current level. */
      for (p = head; p->fts_level >= FTS_ROOTLEVEL;) {
            ADJUST(p);
            p = p->fts_link ? p->fts_link : p->fts_parent;
      }
}

static size_t
internal_function
fts_maxarglen (char * const *argv)
{
      size_t len, max;

      for (max = 0; *argv; ++argv)
            if ((len = strlen(*argv)) > max)
                  max = len;
      return (max + 1);
}

/*
 * Change to dir specified by fd or file name without getting
 * tricked by someone changing the world out from underneath us.
 * Assumes p->fts_statp->st_dev and p->fts_statp->st_ino are filled in.
 */
static int
internal_function
fts_safe_changedir (FTS *sp, FTSENT *p, int fd, char const *dir)
{
      int ret, oerrno, newfd;
      struct stat sb;

      newfd = fd;
      if (ISSET(FTS_NOCHDIR))
            return (0);
      if (fd < 0 && (newfd = diropen (dir)) < 0)
            return (-1);
      if (fstat(newfd, &sb)) {
            ret = -1;
            goto bail;
      }
      if (p->fts_statp->st_dev != sb.st_dev
          || p->fts_statp->st_ino != sb.st_ino) {
            __set_errno (ENOENT);         /* disinformation */
            ret = -1;
            goto bail;
      }
      ret = fchdir(newfd);
bail:
      oerrno = errno;
      if (fd < 0)
            (void)close(newfd);
      __set_errno (oerrno);
      return (ret);
}

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