text: /*-
   * 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.
   */
  
  #if defined(LIBC_SCCS) && !defined(lint)
  static char sccsid[] = "@(#)fts.c	8.6 (Berkeley) 8/14/94";
  #endif /* LIBC_SCCS and not lint */
  
  #include <sys/param.h>
  #include <include/sys/stat.h>
  #include <fcntl.h>
  #include <dirent.h>
  #include <errno.h>
  #include <fts.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  
  /* Largest alignment size needed, minus one.
     Usually long double is the worst case.  */
  #ifndef ALIGNBYTES
  #define ALIGNBYTES	(__alignof__ (long double) - 1)
  #endif
  /* Align P to that size.  */
  #ifndef ALIGN
  #define	ALIGN(p)	(((unsigned long int) (p) + ALIGNBYTES) & ~ALIGNBYTES)
  #endif
  
  
  static FTSENT	*fts_alloc __P((FTS *, const char *, int)) internal_function;
  static FTSENT	*fts_build __P((FTS *, int)) internal_function;
  static void	 fts_lfree __P((FTSENT *)) internal_function;
  static void	 fts_load __P((FTS *, FTSENT *)) internal_function;
  static size_t	 fts_maxarglen __P((char * const *)) internal_function;
  static void	 fts_padjust __P((FTS *, FTSENT *)) internal_function;
  static int	 fts_palloc __P((FTS *, size_t)) internal_function;
  static FTSENT	*fts_sort __P((FTS *, FTSENT *, int)) internal_function;
  static u_short	 fts_stat __P((FTS *, FTSENT *, int)) internal_function;
  static int      fts_safe_changedir __P((FTS *, FTSENT *, int, const char *))
       internal_function;
  
  #ifndef MAX
  #define MAX(a, b)	({ __typeof__ (a) _a = (a); \
  			   __typeof__ (b) _b = (b); \
  			   _a > _b ? _a : _b; })
  #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 */
  
  FTS *
  fts_open(argv, options, compar)
  	char * const *argv;
  	register int options;
  	int (*compar) __P((const FTSENT **, const FTSENT **));
  {
  	register FTS *sp;
  	register FTSENT *p, *root;
  	register int nitems;
  	FTSENT *parent, *tmp;
  	int len;
  
  	/* Options check. */
  	if (options & ~FTS_OPTIONMASK) {
  		__set_errno (EINVAL);
  		return (NULL);
  	}
  
  	/* Allocate/initialize the stream */
  	if ((sp = malloc((u_int)sizeof(FTS))) == NULL)
  		return (NULL);
  	memset(sp, 0, sizeof(FTS));
  	sp->fts_compar = (int (*) __P((const void *, const void *))) 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 path space, and enough, in any case,
  	 * to hold the user's paths.
  	 */
  #ifndef MAXPATHLEN
  #define MAXPATHLEN 1024
  #endif
  	if (fts_palloc(sp, MAX(fts_maxarglen(argv), 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 paths. */
  		if ((len = strlen(*argv)) == 0) {
  			__set_errno (ENOENT);
  			goto mem3;
  		}
  
  		p = fts_alloc(sp, *argv, len);
  		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));
  
  		/* 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 using chdir(2), grab a file descriptor pointing to dot to ensure
  	 * that we can get back here; this could be avoided for some paths,
  	 * 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 = __open(".", O_RDONLY, 0)) < 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(sp, p)
  	FTS *sp;
  	register FTSENT *p;
  {
  	register int 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 path 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_dev;
  }
  
  int
  fts_close(sp)
  	FTS *sp;
  {
  	register FTSENT *freep, *p;
  	int saved_errno;
  
  	/*
  	 * 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, path 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)) {
  		saved_errno = __fchdir(sp->fts_rfd) ? errno : 0;
  		(void)__close(sp->fts_rfd);
  
  		/* Set errno and return. */
  		if (saved_errno != 0) {
  			/* Free up the stream pointer. */
  			free(sp);
  			__set_errno (saved_errno);
  			return (-1);
  		}
  	}
  
  	/* Free up the stream pointer. */
  	free(sp);
  	return (0);
  }
  
  /*
   * Special case of "/" at the end of the path so that slashes aren't
   * appended which would cause paths 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(sp)
  	register FTS *sp;
  {
  	register FTSENT *p, *tmp;
  	register 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, 0);
  		return (p);
  	}
  
  	/*
  	 * 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, 1);
  		if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {
  			if ((p->fts_symfd = __open(".", O_RDONLY, 0)) < 0) {
  				p->fts_errno = errno;
  				p->fts_info = FTS_ERR;
  			} else
  				p->fts_flags |= FTS_SYMFOLLOW;
  		}
  		return (p);
  	}
  
  	/* 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_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;
  			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);
  			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 paths for the next root.
  		 */
  		if (p->fts_level == FTS_ROOTLEVEL) {
  			if (FCHDIR(sp, sp->fts_rfd)) {
  				SET(FTS_STOP);
  				return (NULL);
  			}
  			fts_load(sp, p);
  			return (sp->fts_cur = p);
  		}
  
  		/*
  		 * 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, 1);
  			if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {
  				if ((p->fts_symfd =
  				    __open(".", O_RDONLY, 0)) < 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);
  		return (sp->fts_cur = 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 pathname. */
  	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)) {
  			SET(FTS_STOP);
  			return (NULL);
  		}
  	} 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);
  			SET(FTS_STOP);
  			return (NULL);
  		}
  		(void)__close(p->fts_symfd);
  	} else if (!(p->fts_flags & FTS_DONTCHDIR) &&
  		   fts_safe_changedir(sp, p->fts_parent, -1, "..")) {
  		SET(FTS_STOP);
  		return (NULL);
  	}
  	p->fts_info = p->fts_errno ? FTS_ERR : FTS_DP;
  	return (sp->fts_cur = 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(sp, p, instr)
  	FTS *sp;
  	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(sp, instr)
  	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 path 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 = __open(".", O_RDONLY, 0)) < 0)
  		return (NULL);
  	sp->fts_child = fts_build(sp, instr);
  	if (__fchdir(fd))
  		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(sp, type)
  	register FTS *sp;
  	int type;
  {
  	register struct dirent *dp;
  	register FTSENT *p, *head;
  	register int nitems;
  	FTSENT *cur, *tail;
  	DIR *dirp;
  	void *oldaddr;
  	int cderrno, descend, len, level, maxlen, nlinks, saved_errno,
  	    nostat, doadjust;
  	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(path, flag) __opendir(path)
  #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, -1 if we're doing stats on everything.
  	 */
  	if (type == BNAMES) {
  		nlinks = 0;
  		/* Be quiet about nostat, GCC. */
  		nostat = 0;
  	} else if (ISSET(FTS_NOSTAT) && ISSET(FTS_PHYSICAL)) {
  		nlinks = cur->fts_nlink - (ISSET(FTS_SEEDOT) ? 0 : 2);
  		nostat = 1;
  	} else {
  		nlinks = -1;
  		nostat = 0;
  	}
  
  #ifdef notdef
  	(void)printf("nlinks == %d (cur: %d)\n", nlinks, cur->fts_nlink);
  	(void)printf("NOSTAT %d PHYSICAL %d SEEDOT %d\n",
  	    ISSET(FTS_NOSTAT), ISSET(FTS_PHYSICAL), ISSET(FTS_SEEDOT));
  #endif
  	/*
  	 * 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 path
  	 * 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 = 0;
  			cderrno = errno;
  			(void)__closedir(dirp);
  			dirp = NULL;
  		} else
  			descend = 1;
  	} else
  		descend = 0;
  
  	/*
  	 * Figure out the max file name length that can be stored in the
  	 * current path -- the inner loop allocates more path as necessary.
  	 * We really wouldn't have to do the maxlen calculations here, we
  	 * could do them in fts_read before returning the path, 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 name into the path.
  	 */
  	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 = 0;
  	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, (int)_D_EXACT_NAMLEN (dp))) == NULL)
  			goto mem1;
  		if (_D_EXACT_NAMLEN (dp) >= maxlen) {/* include space for NUL */
  			oldaddr = sp->fts_path;
  			if (fts_palloc(sp, _D_EXACT_NAMLEN (dp) + len + 1)) {
  				/*
  				 * No more memory for path or structures.  Save
  				 * errno, free up the current structure and the
  				 * structures already allocated.
  				 */
  mem1:				saved_errno = errno;
  				if (p)
  					free(p);
  				fts_lfree(head);
  				(void)__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 = 1;
  				if (ISSET(FTS_NOCHDIR))
  					cp = sp->fts_path + len;
  			}
  			maxlen = sp->fts_pathlen - len;
  		}
  
  		if (len + _D_EXACT_NAMLEN (dp) >= USHRT_MAX) {
  			/*
  			 * In an FTSENT, fts_pathlen is a u_short so it is
  			 * possible to wraparound here.  If we do, free up
  			 * the current structure and the structures already
  			 * allocated, then error out with ENAMETOOLONG.
  			 */
  			free(p);
  			fts_lfree(head);
  			(void)__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 = len + _D_EXACT_NAMLEN (dp);
  
  #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 defined DT_DIR && defined _DIRENT_HAVE_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, 0);
  
  			/* Decrement link count if applicable. */
  			if (nlinks > 0 && (p->fts_info == FTS_D ||
  			    p->fts_info == FTS_DC || p->fts_info == FTS_DOT))
  				--nlinks;
  		}
  
  		/* 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)
  		(void)__closedir(dirp);
  
  	/*
  	 * If realloc() changed the address of the path, 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 path 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 path
  	 * 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);
  }
  
  static u_short
  internal_function
  fts_stat(sp, p, follow)
  	FTS *sp;
  	register FTSENT *p;
  	int follow;
  {
  	register FTSENT *t;
  	register dev_t dev;
  	register ino_t ino;
  	struct stat *sbp, sb;
  	int saved_errno;
  
  	/* If user needs stat info, stat buffer already allocated. */
  	sbp = ISSET(FTS_NOSTAT) ? &sb : p->fts_statp;
  
  #if defined FTS_WHITEOUT && 0
  	/* check for whiteout */
  	if (p->fts_flags & FTS_ISW) {
  		if (sbp != &sb) {
  			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 (!lstat(p->fts_accpath, sbp)) {
  				__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)) {
  		/*
  		 * Set the device/inode.  Used to find cycles and check for
  		 * crossing mount points.  Also remember the link count, used
  		 * in fts_build to limit the number of stat calls.  It is
  		 * understood that these fields are only referenced if fts_info
  		 * is set to FTS_D.
  		 */
  		dev = p->fts_dev = sbp->st_dev;
  		ino = p->fts_ino = sbp->st_ino;
  		p->fts_nlink = sbp->st_nlink;
  
  		if (ISDOT(p->fts_name))
  			return (FTS_DOT);
  
  		/*
  		 * 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.
  		 */
  		for (t = p->fts_parent;
  		    t->fts_level >= FTS_ROOTLEVEL; t = t->fts_parent)
  			if (ino == t->fts_ino && dev == t->fts_dev) {
  				p->fts_cycle = t;
  				return (FTS_DC);
  			}
  		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 FTSENT *
  internal_function
  fts_sort(sp, head, nitems)
  	FTS *sp;
  	FTSENT *head;
  	register int nitems;
  {
  	register FTSENT **ap, *p;
  
  	/*
  	 * 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 ((a = realloc(sp->fts_array,
   		    (size_t)(sp->fts_nitems * sizeof(FTSENT *)))) == NULL) {
  			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 *), sp->fts_compar);
  	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(sp, name, namelen)
  	FTS *sp;
  	const char *name;
  	register int namelen;
  {
  	register FTSENT *p;
  	size_t len;
  
  	/*
  	 * The file name is a variable length array and no stat structure is
  	 * necessary if the user has set the nostat bit.  Allocate the FTSENT
  	 * structure, the file name and the stat structure in one chunk, but
  	 * be careful that the stat structure is reasonably aligned.  Since the
  	 * fts_name field is declared to be of size 1, the fts_name pointer is
  	 * namelen + 2 before the first possible address of the stat structure.
  	 */
  	len = sizeof(FTSENT) + namelen;
  	if (!ISSET(FTS_NOSTAT))
  		len += sizeof(struct stat) + ALIGNBYTES;
  	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';
  
  	if (!ISSET(FTS_NOSTAT))
  		p->fts_statp = (struct stat *)ALIGN(p->fts_name + namelen + 2);
  	p->fts_namelen = namelen;
  	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(head)
  	register FTSENT *head;
  {
  	register FTSENT *p;
  
  	/* Free a linked list of structures. */
  	while ((p = head)) {
  		head = head->fts_link;
  		free(p);
  	}
  }
  
  /*
   * Allow essentially unlimited paths; find, rm, ls should all work on any tree.
   * Most systems will allow creation of paths 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 path 2 bytes at a time.
   */
  static int
  internal_function
  fts_palloc(sp, more)
  	FTS *sp;
  	size_t more;
  {
  	char *p;
  
  	sp->fts_pathlen += more + 256;
  	/*
  	 * Check for possible wraparound.  In an FTS, fts_pathlen is
  	 * a signed int but in an FTSENT it is an unsigned short.
  	 * We limit fts_pathlen to USHRT_MAX to be safe in both cases.
  	 */
  	if (sp->fts_pathlen < 0 || sp->fts_pathlen >= USHRT_MAX) {
  		if (sp->fts_path) {
  			free(sp->fts_path);
  			sp->fts_path = NULL;
  		}
  		sp->fts_path = NULL;
  		__set_errno (ENAMETOOLONG);
  		return (1);
  	}
  	p = realloc(sp->fts_path, sp->fts_pathlen);
  	if (p == NULL) {
  		free(sp->fts_path);
  		sp->fts_path = NULL;
  		return 1;
  	}
  	sp->fts_path = p;
  	return 0;
  }
  
  /*
   * When the path is realloc'd, have to fix all of the pointers in structures
   * already returned.
   */
  static void
  internal_function
  fts_padjust(sp, head)
  	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(argv)
  	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 p->fts_accpath without getting
   * tricked by someone changing the world out from underneath us.
   * Assumes p->fts_dev and p->fts_ino are filled in.
   */
  static int
  internal_function
  fts_safe_changedir(sp, p, fd, path)
  	FTS *sp;
  	FTSENT *p;
  	int fd;
  	const char *path;
  {
  	int ret, oerrno, newfd;
  	struct stat64 sb;
  
  	newfd = fd;
  	if (ISSET(FTS_NOCHDIR))
  		return (0);
  	if (fd < 0 && (newfd = __open(path, O_RDONLY, 0)) < 0)
  		return (-1);
  	if (__fxstat64(_STAT_VER, newfd, &sb)) {
  		ret = -1;
  		goto bail;
  	}
  	if (p->fts_dev != sb.st_dev || p->fts_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);
  }
  