/*	$NetBSD: fts.c,v 1.44 2012/03/14 00:25:19 christos Exp $	*/

/*-

 * 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.

 * 3. 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 0

static char sccsid[] = "@(#)fts.c	8.6 (Berkeley) 8/14/94";

#else

/* __RCSID("$NetBSD: fts.c,v 1.44 2012/03/14 00:25:19 christos Exp $"); */

#endif

#ifdef HAVE_CONFIG_H

#include <config.h>

#endif

#define _BSD_SOURCE

#include <limits.h>

/* #include "namespace.h" */

#ifdef HAVE_SYS_PARAM_H

#include <sys/param.h>

#else

#include <stdio.h>

#endif

#include <sys/stat.h>

#include <assert.h>

#include <dirent.h>

#include <errno.h>

#include <fcntl.h>

#include "gawkfts.h"

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include "gawkdirfd.h"

#if ! defined(S_ISREG) && defined(S_IFREG)

#define	S_ISREG(m) (((m) & S_IFMT) == S_IFREG)

#endif

/*

#if ! HAVE_NBTOOL_CONFIG_H

#define	HAVE_STRUCT_DIRENT_D_NAMLEN

#endif

*/

#ifndef MAX

static int MAX(int x, int y)

{

	if (x > y)

		return x;

	return y;

}

#endif

static FTSENT	*fts_alloc(FTS *, const char *, size_t);

static FTSENT	*fts_build(FTS *, int);

static void	 fts_free(FTSENT *);

static void	 fts_lfree(FTSENT *);

static void	 fts_load(FTS *, FTSENT *);

static size_t	 fts_maxarglen(char * const *);

static size_t	 fts_pow2(size_t);

static int	 fts_palloc(FTS *, size_t);

static void	 fts_padjust(FTS *, FTSENT *);

static FTSENT	*fts_sort(FTS *, FTSENT *, size_t);

static unsigned short fts_stat(FTS *, FTSENT *, int);

static int	 fts_safe_changedir(const FTS *, const FTSENT *, int,

    const char *);

#if defined(ALIGNBYTES) && defined(ALIGN)

#define	FTS_ALLOC_ALIGNED	1

#else

#undef	FTS_ALLOC_ALIGNED

#endif

#ifndef ftsent_namelen_truncate

#define ftsent_namelen_truncate(a)	\

    ((a) > UINT_MAX ? UINT_MAX : (unsigned int)(a))

#endif

#ifndef ftsent_pathlen_truncate

#define ftsent_pathlen_truncate(a) \

    ((a) > UINT_MAX ? UINT_MAX : (unsigned int)(a))

#endif

#ifndef fts_pathlen_truncate

#define fts_pathlen_truncate(a)	\

    ((a) > UINT_MAX ? UINT_MAX : (unsigned int)(a))

#endif

#ifndef fts_nitems_truncate

#define fts_nitems_truncate(a) \

    ((a) > UINT_MAX ? UINT_MAX : (unsigned int)(a))

#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	CHDIR(sp, path)	(!ISSET(FTS_NOCHDIR) && chdir(path))

#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 */

#ifndef DTF_HIDEW

#undef FTS_WHITEOUT

#endif

#define _DIAGASSERT(expression)

#ifndef MAXPATHLEN

#define MAXPATHLEN	1024	/* a guess */

#endif

FTS *

fts_open(char * const *argv, int options,

    int (*compar)(const FTSENT **, const FTSENT **))

{

	FTS *sp;

	FTSENT *p, *root;

	size_t nitems;

	FTSENT *parent, *tmp = NULL;	/* pacify gcc */

	size_t len;

	_DIAGASSERT(argv != NULL);

	/* Options check. */

	if (options & ~FTS_OPTIONMASK) {

		errno = EINVAL;

		return (NULL);

	}

	/* Allocate/initialize the stream */

	if ((sp = calloc(1, (unsigned int)sizeof(FTS))) == NULL)

		return (NULL);

	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 path space, and enough, in any case,

	 * to hold the user's paths.

	 */

	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; ++argv, ++nitems) {

		/* Don't allow zero-length paths. */

		if ((len = strlen(*argv)) == 0) {

			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));

		/* 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 insure

	 * 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.

	 */

#ifndef O_CLOEXEC

#define O_CLOEXEC 0

#endif

	if (!ISSET(FTS_NOCHDIR)) {

		if ((sp->fts_rfd = open(".", O_RDONLY | O_CLOEXEC, 0)) == -1)

			SET(FTS_NOCHDIR);

	}

	if (nitems == 0)

		fts_free(parent);

	return (sp);

mem3:	fts_lfree(root);

	fts_free(parent);

mem2:	free(sp->fts_path);

mem1:	free(sp);

	return (NULL);

}

static void

fts_load(FTS *sp, FTSENT *p)

{

	size_t len;

	char *cp;

	_DIAGASSERT(sp != NULL);

	_DIAGASSERT(p != NULL);

	/*

	 * 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 = ftsent_namelen_truncate(len);

	}

	p->fts_accpath = p->fts_path = sp->fts_path;

	sp->fts_dev = p->fts_dev;

}

int

fts_close(FTS *sp)

{

	FTSENT *freep, *p;

	int saved_errno = 0;

	_DIAGASSERT(sp != NULL);

	/*

	 * 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) {

		if (sp->fts_cur->fts_flags & FTS_SYMFOLLOW)

			(void)close(sp->fts_cur->fts_symfd);

		for (p = sp->fts_cur; p->fts_level >= FTS_ROOTLEVEL;) {

			freep = p;

			p = p->fts_link ? p->fts_link : p->fts_parent;

			fts_free(freep);

		}

		fts_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)) {

		if (fchdir(sp->fts_rfd) == -1)

			saved_errno = errno;

		(void)close(sp->fts_rfd);

	}

	/* Free up the stream pointer. */

	free(sp);

	if (saved_errno) {

		errno = saved_errno;

		return -1;

	}

	return 0;

}

#if !defined(__FTS_COMPAT_TAILINGSLASH)

/*

 * 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)

#else /* !defined(__FTS_COMPAT_TAILINGSLASH) */

/*

 * compatibility with the old behaviour.

 *

 * Special case a root of "/" so that slashes aren't appended which would

 * cause paths to be written as "//foo".

 */

#define	NAPPEND(p)							\

	(p->fts_level == FTS_ROOTLEVEL && p->fts_pathlen == 1 &&	\

	    p->fts_path[0] == '/' ? 0 : p->fts_pathlen)

#endif /* !defined(__FTS_COMPAT_TAILINGSLASH) */

FTSENT *

fts_read(FTS *sp)

{

	FTSENT *p, *tmp;

	int instr;

	char *t;

	int saved_errno;

	_DIAGASSERT(sp != NULL);

	/* 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 | O_CLOEXEC, 0))

			    == -1) {

				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 && 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) {

			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; 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) {

		fts_free(tmp);

		/*

		 * If reached the top, return to the original directory, 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 | O_CLOEXEC, 0)) == -1) {

					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, (size_t)(p->fts_namelen + 1));

		return (sp->fts_cur = p);

	}

	/* Move up to the parent node. */

	p = tmp->fts_parent;

	fts_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.

		 */

		fts_free(p);

		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);

			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(FTS *sp, FTSENT *p, int instr)

{

	(void) sp;	/* silence warnings */

	_DIAGASSERT(sp != NULL);

	_DIAGASSERT(p != NULL);

	if (instr && instr != FTS_AGAIN && instr != FTS_FOLLOW &&

	    instr != FTS_NOINSTR && instr != FTS_SKIP) {

		errno = EINVAL;

		return (1);

	}

	p->fts_instr = instr;

	return (0);

}

FTSENT *

fts_children(FTS *sp, int instr)

{

	FTSENT *p;

	int fd;

	_DIAGASSERT(sp != NULL);

	if (instr && instr != FTS_NAMEONLY) {

		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.

	 */

	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)

		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)) == -1)

		return (sp->fts_child = NULL);

	sp->fts_child = fts_build(sp, instr);

	if (fchdir(fd)) {

		(void)close(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 *

fts_build(FTS *sp, int type)

{

	struct dirent *dp;

	FTSENT *p, *head;

	size_t nitems;

	FTSENT *cur, *tail;

	DIR *dirp;

	void *oldaddr;

	size_t dnamlen;

	int cderrno, descend, level, nlinks, saved_errno, nostat, doadjust;

	size_t len, maxlen;

#ifdef FTS_WHITEOUT

	int oflag;

#endif

	char *cp = NULL;	/* pacify gcc */

	_DIAGASSERT(sp != NULL);

	/* 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 0 /* def FTS_WHITEOUT */

	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;

		nostat = 1;

	} 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;

		} 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++ = '/';

	}

	len++;

	maxlen = sp->fts_pathlen - len;

#if defined(__FTS_COMPAT_LEVEL)

	if (cur->fts_level == SHRT_MAX) {

		(void)closedir(dirp);

		cur->fts_info = FTS_ERR;

		SET(FTS_STOP);

		errno = ENAMETOOLONG;

		return (NULL);

	}

#endif

	level = cur->fts_level + 1;

	/* Read the directory, attaching each entry to the `link' pointer. */

	doadjust = 0;

	for (head = tail = NULL, nitems = 0; (dp = readdir(dirp)) != NULL;) {

		if (!ISSET(FTS_SEEDOT) && ISDOT(dp->d_name))

			continue;

#if defined(HAVE_STRUCT_DIRENT_D_NAMLEN)

		dnamlen = dp->d_namlen;

#else

		dnamlen = strlen(dp->d_name);

#endif

		if ((p = fts_alloc(sp, dp->d_name, dnamlen)) == NULL)

			goto mem1;

		if (dnamlen >= maxlen) {	/* include space for NUL */

			oldaddr = sp->fts_path;

			if (fts_palloc(sp, dnamlen + 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)

					fts_free(p);

				fts_lfree(head);

				(void)closedir(dirp);

				errno = saved_errno;

				cur->fts_info = FTS_ERR;

				SET(FTS_STOP);

				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 defined(__FTS_COMPAT_LENGTH)

		if (len + dnamlen >= USHRT_MAX) {

			/*

			 * In an FTSENT, fts_pathlen is an unsigned 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.

			 */

			fts_free(p);

			fts_lfree(head);

			(void)closedir(dirp);

			cur->fts_info = FTS_ERR;

			SET(FTS_STOP);

			errno = ENAMETOOLONG;

			return (NULL);

		}

#endif

		p->fts_level = level;

		p->fts_pathlen = ftsent_pathlen_truncate(len + dnamlen);

		p->fts_parent = sp->fts_cur;

#ifdef FTS_WHITEOUT

		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

#ifdef DT_DIR

		    || (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,

				        (size_t)(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;