xref: /freebsd/lib/libc/gen/fts-compat.c (revision 64a0982bee3db2236df43357e70ce8dddbc21d48)
1 /*-
2  * Copyright (c) 1990, 1993, 1994
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  * $OpenBSD: fts.c,v 1.22 1999/10/03 19:22:22 millert Exp $
30  */
31 
32 #if 0
33 #if defined(LIBC_SCCS) && !defined(lint)
34 static char sccsid[] = "@(#)fts.c	8.6 (Berkeley) 8/14/94";
35 #endif /* LIBC_SCCS and not lint */
36 #endif
37 
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 #include "namespace.h"
42 #include <sys/param.h>
43 #include <sys/mount.h>
44 #include <sys/stat.h>
45 
46 #include <dirent.h>
47 #include <errno.h>
48 #include <fcntl.h>
49 #include <stdlib.h>
50 #include <string.h>
51 #include <unistd.h>
52 #include "fts-compat.h"
53 #include "un-namespace.h"
54 
55 #include "gen-private.h"
56 
57 FTSENT	*__fts_children_44bsd(FTS *, int);
58 int	 __fts_close_44bsd(FTS *);
59 void	*__fts_get_clientptr_44bsd(FTS *);
60 FTS	*__fts_get_stream_44bsd(FTSENT *);
61 FTS	*__fts_open_44bsd(char * const *, int,
62 	    int (*)(const FTSENT * const *, const FTSENT * const *));
63 FTSENT	*__fts_read_44bsd(FTS *);
64 int	 __fts_set_44bsd(FTS *, FTSENT *, int);
65 void	 __fts_set_clientptr_44bsd(FTS *, void *);
66 
67 static FTSENT	*fts_alloc(FTS *, char *, int);
68 static FTSENT	*fts_build(FTS *, int);
69 static void	 fts_lfree(FTSENT *);
70 static void	 fts_load(FTS *, FTSENT *);
71 static size_t	 fts_maxarglen(char * const *);
72 static void	 fts_padjust(FTS *, FTSENT *);
73 static int	 fts_palloc(FTS *, size_t);
74 static FTSENT	*fts_sort(FTS *, FTSENT *, int);
75 static u_short	 fts_stat(FTS *, FTSENT *, int);
76 static int	 fts_safe_changedir(FTS *, FTSENT *, int, char *);
77 static int	 fts_ufslinks(FTS *, const FTSENT *);
78 
79 #define	ISDOT(a)	(a[0] == '.' && (!a[1] || (a[1] == '.' && !a[2])))
80 
81 #define	CLR(opt)	(sp->fts_options &= ~(opt))
82 #define	ISSET(opt)	(sp->fts_options & (opt))
83 #define	SET(opt)	(sp->fts_options |= (opt))
84 
85 #define	FCHDIR(sp, fd)	(!ISSET(FTS_NOCHDIR) && fchdir(fd))
86 
87 /* fts_build flags */
88 #define	BCHILD		1		/* fts_children */
89 #define	BNAMES		2		/* fts_children, names only */
90 #define	BREAD		3		/* fts_read */
91 
92 /*
93  * Internal representation of an FTS, including extra implementation
94  * details.  The FTS returned from fts_open points to this structure's
95  * ftsp_fts member (and can be cast to an _fts_private as required)
96  */
97 struct _fts_private {
98 	FTS		ftsp_fts;
99 	struct statfs	ftsp_statfs;
100 	dev_t		ftsp_dev;
101 	int		ftsp_linksreliable;
102 };
103 
104 /*
105  * The "FTS_NOSTAT" option can avoid a lot of calls to stat(2) if it
106  * knows that a directory could not possibly have subdirectories.  This
107  * is decided by looking at the link count: a subdirectory would
108  * increment its parent's link count by virtue of its own ".." entry.
109  * This assumption only holds for UFS-like filesystems that implement
110  * links and directories this way, so we must punt for others.
111  */
112 
113 static const char *ufslike_filesystems[] = {
114 	"ufs",
115 	"zfs",
116 	"nfs",
117 	"ext2fs",
118 	0
119 };
120 
121 FTS *
122 __fts_open_44bsd(char * const *argv, int options,
123     int (*compar)(const FTSENT * const *, const FTSENT * const *))
124 {
125 	struct _fts_private *priv;
126 	FTS *sp;
127 	FTSENT *p, *root;
128 	int nitems;
129 	FTSENT *parent, *tmp;
130 	int len;
131 
132 	/* Options check. */
133 	if (options & ~FTS_OPTIONMASK) {
134 		errno = EINVAL;
135 		return (NULL);
136 	}
137 
138 	/* Allocate/initialize the stream. */
139 	if ((priv = calloc(1, sizeof(*priv))) == NULL)
140 		return (NULL);
141 	sp = &priv->ftsp_fts;
142 	sp->fts_compar = compar;
143 	sp->fts_options = options;
144 
145 	/* Shush, GCC. */
146 	tmp = NULL;
147 
148 	/* Logical walks turn on NOCHDIR; symbolic links are too hard. */
149 	if (ISSET(FTS_LOGICAL))
150 		SET(FTS_NOCHDIR);
151 
152 	/*
153 	 * Start out with 1K of path space, and enough, in any case,
154 	 * to hold the user's paths.
155 	 */
156 	if (fts_palloc(sp, MAX(fts_maxarglen(argv), MAXPATHLEN)))
157 		goto mem1;
158 
159 	/* Allocate/initialize root's parent. */
160 	if ((parent = fts_alloc(sp, "", 0)) == NULL)
161 		goto mem2;
162 	parent->fts_level = FTS_ROOTPARENTLEVEL;
163 
164 	/* Allocate/initialize root(s). */
165 	for (root = NULL, nitems = 0; *argv != NULL; ++argv, ++nitems) {
166 		/* Don't allow zero-length paths. */
167 		if ((len = strlen(*argv)) == 0) {
168 			errno = ENOENT;
169 			goto mem3;
170 		}
171 
172 		p = fts_alloc(sp, *argv, len);
173 		p->fts_level = FTS_ROOTLEVEL;
174 		p->fts_parent = parent;
175 		p->fts_accpath = p->fts_name;
176 		p->fts_info = fts_stat(sp, p, ISSET(FTS_COMFOLLOW));
177 
178 		/* Command-line "." and ".." are real directories. */
179 		if (p->fts_info == FTS_DOT)
180 			p->fts_info = FTS_D;
181 
182 		/*
183 		 * If comparison routine supplied, traverse in sorted
184 		 * order; otherwise traverse in the order specified.
185 		 */
186 		if (compar) {
187 			p->fts_link = root;
188 			root = p;
189 		} else {
190 			p->fts_link = NULL;
191 			if (root == NULL)
192 				tmp = root = p;
193 			else {
194 				tmp->fts_link = p;
195 				tmp = p;
196 			}
197 		}
198 	}
199 	if (compar && nitems > 1)
200 		root = fts_sort(sp, root, nitems);
201 
202 	/*
203 	 * Allocate a dummy pointer and make fts_read think that we've just
204 	 * finished the node before the root(s); set p->fts_info to FTS_INIT
205 	 * so that everything about the "current" node is ignored.
206 	 */
207 	if ((sp->fts_cur = fts_alloc(sp, "", 0)) == NULL)
208 		goto mem3;
209 	sp->fts_cur->fts_link = root;
210 	sp->fts_cur->fts_info = FTS_INIT;
211 
212 	/*
213 	 * If using chdir(2), grab a file descriptor pointing to dot to ensure
214 	 * that we can get back here; this could be avoided for some paths,
215 	 * but almost certainly not worth the effort.  Slashes, symbolic links,
216 	 * and ".." are all fairly nasty problems.  Note, if we can't get the
217 	 * descriptor we run anyway, just more slowly.
218 	 */
219 	if (!ISSET(FTS_NOCHDIR) &&
220 	    (sp->fts_rfd = _open(".", O_RDONLY | O_CLOEXEC, 0)) < 0)
221 		SET(FTS_NOCHDIR);
222 
223 	return (sp);
224 
225 mem3:	fts_lfree(root);
226 	free(parent);
227 mem2:	free(sp->fts_path);
228 mem1:	free(sp);
229 	return (NULL);
230 }
231 
232 static void
233 fts_load(FTS *sp, FTSENT *p)
234 {
235 	int len;
236 	char *cp;
237 
238 	/*
239 	 * Load the stream structure for the next traversal.  Since we don't
240 	 * actually enter the directory until after the preorder visit, set
241 	 * the fts_accpath field specially so the chdir gets done to the right
242 	 * place and the user can access the first node.  From fts_open it's
243 	 * known that the path will fit.
244 	 */
245 	len = p->fts_pathlen = p->fts_namelen;
246 	memmove(sp->fts_path, p->fts_name, len + 1);
247 	if ((cp = strrchr(p->fts_name, '/')) && (cp != p->fts_name || cp[1])) {
248 		len = strlen(++cp);
249 		memmove(p->fts_name, cp, len + 1);
250 		p->fts_namelen = len;
251 	}
252 	p->fts_accpath = p->fts_path = sp->fts_path;
253 	sp->fts_dev = p->fts_dev;
254 }
255 
256 int
257 __fts_close_44bsd(FTS *sp)
258 {
259 	FTSENT *freep, *p;
260 	int saved_errno;
261 
262 	/*
263 	 * This still works if we haven't read anything -- the dummy structure
264 	 * points to the root list, so we step through to the end of the root
265 	 * list which has a valid parent pointer.
266 	 */
267 	if (sp->fts_cur) {
268 		for (p = sp->fts_cur; p->fts_level >= FTS_ROOTLEVEL;) {
269 			freep = p;
270 			p = p->fts_link != NULL ? p->fts_link : p->fts_parent;
271 			free(freep);
272 		}
273 		free(p);
274 	}
275 
276 	/* Free up child linked list, sort array, path buffer. */
277 	if (sp->fts_child)
278 		fts_lfree(sp->fts_child);
279 	if (sp->fts_array)
280 		free(sp->fts_array);
281 	free(sp->fts_path);
282 
283 	/* Return to original directory, save errno if necessary. */
284 	if (!ISSET(FTS_NOCHDIR)) {
285 		saved_errno = fchdir(sp->fts_rfd) ? errno : 0;
286 		(void)_close(sp->fts_rfd);
287 
288 		/* Set errno and return. */
289 		if (saved_errno != 0) {
290 			/* Free up the stream pointer. */
291 			free(sp);
292 			errno = saved_errno;
293 			return (-1);
294 		}
295 	}
296 
297 	/* Free up the stream pointer. */
298 	free(sp);
299 	return (0);
300 }
301 
302 /*
303  * Special case of "/" at the end of the path so that slashes aren't
304  * appended which would cause paths to be written as "....//foo".
305  */
306 #define	NAPPEND(p)							\
307 	(p->fts_path[p->fts_pathlen - 1] == '/'				\
308 	    ? p->fts_pathlen - 1 : p->fts_pathlen)
309 
310 FTSENT *
311 __fts_read_44bsd(FTS *sp)
312 {
313 	FTSENT *p, *tmp;
314 	int instr;
315 	char *t;
316 	int saved_errno;
317 
318 	/* If finished or unrecoverable error, return NULL. */
319 	if (sp->fts_cur == NULL || ISSET(FTS_STOP))
320 		return (NULL);
321 
322 	/* Set current node pointer. */
323 	p = sp->fts_cur;
324 
325 	/* Save and zero out user instructions. */
326 	instr = p->fts_instr;
327 	p->fts_instr = FTS_NOINSTR;
328 
329 	/* Any type of file may be re-visited; re-stat and re-turn. */
330 	if (instr == FTS_AGAIN) {
331 		p->fts_info = fts_stat(sp, p, 0);
332 		return (p);
333 	}
334 
335 	/*
336 	 * Following a symlink -- SLNONE test allows application to see
337 	 * SLNONE and recover.  If indirecting through a symlink, have
338 	 * keep a pointer to current location.  If unable to get that
339 	 * pointer, follow fails.
340 	 */
341 	if (instr == FTS_FOLLOW &&
342 	    (p->fts_info == FTS_SL || p->fts_info == FTS_SLNONE)) {
343 		p->fts_info = fts_stat(sp, p, 1);
344 		if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {
345 			if ((p->fts_symfd = _open(".", O_RDONLY | O_CLOEXEC,
346 			    0)) < 0) {
347 				p->fts_errno = errno;
348 				p->fts_info = FTS_ERR;
349 			} else
350 				p->fts_flags |= FTS_SYMFOLLOW;
351 		}
352 		return (p);
353 	}
354 
355 	/* Directory in pre-order. */
356 	if (p->fts_info == FTS_D) {
357 		/* If skipped or crossed mount point, do post-order visit. */
358 		if (instr == FTS_SKIP ||
359 		    (ISSET(FTS_XDEV) && p->fts_dev != sp->fts_dev)) {
360 			if (p->fts_flags & FTS_SYMFOLLOW)
361 				(void)_close(p->fts_symfd);
362 			if (sp->fts_child) {
363 				fts_lfree(sp->fts_child);
364 				sp->fts_child = NULL;
365 			}
366 			p->fts_info = FTS_DP;
367 			return (p);
368 		}
369 
370 		/* Rebuild if only read the names and now traversing. */
371 		if (sp->fts_child != NULL && ISSET(FTS_NAMEONLY)) {
372 			CLR(FTS_NAMEONLY);
373 			fts_lfree(sp->fts_child);
374 			sp->fts_child = NULL;
375 		}
376 
377 		/*
378 		 * Cd to the subdirectory.
379 		 *
380 		 * If have already read and now fail to chdir, whack the list
381 		 * to make the names come out right, and set the parent errno
382 		 * so the application will eventually get an error condition.
383 		 * Set the FTS_DONTCHDIR flag so that when we logically change
384 		 * directories back to the parent we don't do a chdir.
385 		 *
386 		 * If haven't read do so.  If the read fails, fts_build sets
387 		 * FTS_STOP or the fts_info field of the node.
388 		 */
389 		if (sp->fts_child != NULL) {
390 			if (fts_safe_changedir(sp, p, -1, p->fts_accpath)) {
391 				p->fts_errno = errno;
392 				p->fts_flags |= FTS_DONTCHDIR;
393 				for (p = sp->fts_child; p != NULL;
394 				    p = p->fts_link)
395 					p->fts_accpath =
396 					    p->fts_parent->fts_accpath;
397 			}
398 		} else if ((sp->fts_child = fts_build(sp, BREAD)) == NULL) {
399 			if (ISSET(FTS_STOP))
400 				return (NULL);
401 			return (p);
402 		}
403 		p = sp->fts_child;
404 		sp->fts_child = NULL;
405 		goto name;
406 	}
407 
408 	/* Move to the next node on this level. */
409 next:	tmp = p;
410 	if ((p = p->fts_link) != NULL) {
411 		free(tmp);
412 
413 		/*
414 		 * If reached the top, return to the original directory (or
415 		 * the root of the tree), and load the paths for the next root.
416 		 */
417 		if (p->fts_level == FTS_ROOTLEVEL) {
418 			if (FCHDIR(sp, sp->fts_rfd)) {
419 				SET(FTS_STOP);
420 				return (NULL);
421 			}
422 			fts_load(sp, p);
423 			return (sp->fts_cur = p);
424 		}
425 
426 		/*
427 		 * User may have called fts_set on the node.  If skipped,
428 		 * ignore.  If followed, get a file descriptor so we can
429 		 * get back if necessary.
430 		 */
431 		if (p->fts_instr == FTS_SKIP)
432 			goto next;
433 		if (p->fts_instr == FTS_FOLLOW) {
434 			p->fts_info = fts_stat(sp, p, 1);
435 			if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {
436 				if ((p->fts_symfd =
437 				    _open(".", O_RDONLY | O_CLOEXEC, 0)) < 0) {
438 					p->fts_errno = errno;
439 					p->fts_info = FTS_ERR;
440 				} else
441 					p->fts_flags |= FTS_SYMFOLLOW;
442 			}
443 			p->fts_instr = FTS_NOINSTR;
444 		}
445 
446 name:		t = sp->fts_path + NAPPEND(p->fts_parent);
447 		*t++ = '/';
448 		memmove(t, p->fts_name, p->fts_namelen + 1);
449 		return (sp->fts_cur = p);
450 	}
451 
452 	/* Move up to the parent node. */
453 	p = tmp->fts_parent;
454 	free(tmp);
455 
456 	if (p->fts_level == FTS_ROOTPARENTLEVEL) {
457 		/*
458 		 * Done; free everything up and set errno to 0 so the user
459 		 * can distinguish between error and EOF.
460 		 */
461 		free(p);
462 		errno = 0;
463 		return (sp->fts_cur = NULL);
464 	}
465 
466 	/* NUL terminate the pathname. */
467 	sp->fts_path[p->fts_pathlen] = '\0';
468 
469 	/*
470 	 * Return to the parent directory.  If at a root node or came through
471 	 * a symlink, go back through the file descriptor.  Otherwise, cd up
472 	 * one directory.
473 	 */
474 	if (p->fts_level == FTS_ROOTLEVEL) {
475 		if (FCHDIR(sp, sp->fts_rfd)) {
476 			SET(FTS_STOP);
477 			return (NULL);
478 		}
479 	} else if (p->fts_flags & FTS_SYMFOLLOW) {
480 		if (FCHDIR(sp, p->fts_symfd)) {
481 			saved_errno = errno;
482 			(void)_close(p->fts_symfd);
483 			errno = saved_errno;
484 			SET(FTS_STOP);
485 			return (NULL);
486 		}
487 		(void)_close(p->fts_symfd);
488 	} else if (!(p->fts_flags & FTS_DONTCHDIR) &&
489 	    fts_safe_changedir(sp, p->fts_parent, -1, "..")) {
490 		SET(FTS_STOP);
491 		return (NULL);
492 	}
493 	p->fts_info = p->fts_errno ? FTS_ERR : FTS_DP;
494 	return (sp->fts_cur = p);
495 }
496 
497 /*
498  * Fts_set takes the stream as an argument although it's not used in this
499  * implementation; it would be necessary if anyone wanted to add global
500  * semantics to fts using fts_set.  An error return is allowed for similar
501  * reasons.
502  */
503 /* ARGSUSED */
504 int
505 __fts_set_44bsd(FTS *sp, FTSENT *p, int instr)
506 {
507 	if (instr != 0 && instr != FTS_AGAIN && instr != FTS_FOLLOW &&
508 	    instr != FTS_NOINSTR && instr != FTS_SKIP) {
509 		errno = EINVAL;
510 		return (1);
511 	}
512 	p->fts_instr = instr;
513 	return (0);
514 }
515 
516 FTSENT *
517 __fts_children_44bsd(FTS *sp, int instr)
518 {
519 	FTSENT *p;
520 	int fd;
521 
522 	if (instr != 0 && instr != FTS_NAMEONLY) {
523 		errno = EINVAL;
524 		return (NULL);
525 	}
526 
527 	/* Set current node pointer. */
528 	p = sp->fts_cur;
529 
530 	/*
531 	 * Errno set to 0 so user can distinguish empty directory from
532 	 * an error.
533 	 */
534 	errno = 0;
535 
536 	/* Fatal errors stop here. */
537 	if (ISSET(FTS_STOP))
538 		return (NULL);
539 
540 	/* Return logical hierarchy of user's arguments. */
541 	if (p->fts_info == FTS_INIT)
542 		return (p->fts_link);
543 
544 	/*
545 	 * If not a directory being visited in pre-order, stop here.  Could
546 	 * allow FTS_DNR, assuming the user has fixed the problem, but the
547 	 * same effect is available with FTS_AGAIN.
548 	 */
549 	if (p->fts_info != FTS_D /* && p->fts_info != FTS_DNR */)
550 		return (NULL);
551 
552 	/* Free up any previous child list. */
553 	if (sp->fts_child != NULL)
554 		fts_lfree(sp->fts_child);
555 
556 	if (instr == FTS_NAMEONLY) {
557 		SET(FTS_NAMEONLY);
558 		instr = BNAMES;
559 	} else
560 		instr = BCHILD;
561 
562 	/*
563 	 * If using chdir on a relative path and called BEFORE fts_read does
564 	 * its chdir to the root of a traversal, we can lose -- we need to
565 	 * chdir into the subdirectory, and we don't know where the current
566 	 * directory is, so we can't get back so that the upcoming chdir by
567 	 * fts_read will work.
568 	 */
569 	if (p->fts_level != FTS_ROOTLEVEL || p->fts_accpath[0] == '/' ||
570 	    ISSET(FTS_NOCHDIR))
571 		return (sp->fts_child = fts_build(sp, instr));
572 
573 	if ((fd = _open(".", O_RDONLY | O_CLOEXEC, 0)) < 0)
574 		return (NULL);
575 	sp->fts_child = fts_build(sp, instr);
576 	if (fchdir(fd)) {
577 		(void)_close(fd);
578 		return (NULL);
579 	}
580 	(void)_close(fd);
581 	return (sp->fts_child);
582 }
583 
584 #ifndef fts_get_clientptr
585 #error "fts_get_clientptr not defined"
586 #endif
587 
588 void *
589 (__fts_get_clientptr_44bsd)(FTS *sp)
590 {
591 
592 	return (fts_get_clientptr(sp));
593 }
594 
595 #ifndef fts_get_stream
596 #error "fts_get_stream not defined"
597 #endif
598 
599 FTS *
600 (__fts_get_stream_44bsd)(FTSENT *p)
601 {
602 	return (fts_get_stream(p));
603 }
604 
605 void
606 __fts_set_clientptr_44bsd(FTS *sp, void *clientptr)
607 {
608 
609 	sp->fts_clientptr = clientptr;
610 }
611 
612 /*
613  * This is the tricky part -- do not casually change *anything* in here.  The
614  * idea is to build the linked list of entries that are used by fts_children
615  * and fts_read.  There are lots of special cases.
616  *
617  * The real slowdown in walking the tree is the stat calls.  If FTS_NOSTAT is
618  * set and it's a physical walk (so that symbolic links can't be directories),
619  * we can do things quickly.  First, if it's a 4.4BSD file system, the type
620  * of the file is in the directory entry.  Otherwise, we assume that the number
621  * of subdirectories in a node is equal to the number of links to the parent.
622  * The former skips all stat calls.  The latter skips stat calls in any leaf
623  * directories and for any files after the subdirectories in the directory have
624  * been found, cutting the stat calls by about 2/3.
625  */
626 static FTSENT *
627 fts_build(FTS *sp, int type)
628 {
629 	struct dirent *dp;
630 	FTSENT *p, *head;
631 	int nitems;
632 	FTSENT *cur, *tail;
633 	DIR *dirp;
634 	void *oldaddr;
635 	size_t dnamlen;
636 	int cderrno, descend, len, level, maxlen, nlinks, oflag, saved_errno,
637 	    nostat, doadjust;
638 	char *cp;
639 
640 	/* Set current node pointer. */
641 	cur = sp->fts_cur;
642 
643 	/*
644 	 * Open the directory for reading.  If this fails, we're done.
645 	 * If being called from fts_read, set the fts_info field.
646 	 */
647 #ifdef FTS_WHITEOUT
648 	if (ISSET(FTS_WHITEOUT))
649 		oflag = DTF_NODUP | DTF_REWIND;
650 	else
651 		oflag = DTF_HIDEW | DTF_NODUP | DTF_REWIND;
652 #else
653 #define __opendir2(path, flag) opendir(path)
654 #endif
655 	if ((dirp = __opendir2(cur->fts_accpath, oflag)) == NULL) {
656 		if (type == BREAD) {
657 			cur->fts_info = FTS_DNR;
658 			cur->fts_errno = errno;
659 		}
660 		return (NULL);
661 	}
662 
663 	/*
664 	 * Nlinks is the number of possible entries of type directory in the
665 	 * directory if we're cheating on stat calls, 0 if we're not doing
666 	 * any stat calls at all, -1 if we're doing stats on everything.
667 	 */
668 	if (type == BNAMES) {
669 		nlinks = 0;
670 		/* Be quiet about nostat, GCC. */
671 		nostat = 0;
672 	} else if (ISSET(FTS_NOSTAT) && ISSET(FTS_PHYSICAL)) {
673 		if (fts_ufslinks(sp, cur))
674 			nlinks = cur->fts_nlink - (ISSET(FTS_SEEDOT) ? 0 : 2);
675 		else
676 			nlinks = -1;
677 		nostat = 1;
678 	} else {
679 		nlinks = -1;
680 		nostat = 0;
681 	}
682 
683 #ifdef notdef
684 	(void)printf("nlinks == %d (cur: %d)\n", nlinks, cur->fts_nlink);
685 	(void)printf("NOSTAT %d PHYSICAL %d SEEDOT %d\n",
686 	    ISSET(FTS_NOSTAT), ISSET(FTS_PHYSICAL), ISSET(FTS_SEEDOT));
687 #endif
688 	/*
689 	 * If we're going to need to stat anything or we want to descend
690 	 * and stay in the directory, chdir.  If this fails we keep going,
691 	 * but set a flag so we don't chdir after the post-order visit.
692 	 * We won't be able to stat anything, but we can still return the
693 	 * names themselves.  Note, that since fts_read won't be able to
694 	 * chdir into the directory, it will have to return different path
695 	 * names than before, i.e. "a/b" instead of "b".  Since the node
696 	 * has already been visited in pre-order, have to wait until the
697 	 * post-order visit to return the error.  There is a special case
698 	 * here, if there was nothing to stat then it's not an error to
699 	 * not be able to stat.  This is all fairly nasty.  If a program
700 	 * needed sorted entries or stat information, they had better be
701 	 * checking FTS_NS on the returned nodes.
702 	 */
703 	cderrno = 0;
704 	if (nlinks || type == BREAD) {
705 		if (fts_safe_changedir(sp, cur, _dirfd(dirp), NULL)) {
706 			if (nlinks && type == BREAD)
707 				cur->fts_errno = errno;
708 			cur->fts_flags |= FTS_DONTCHDIR;
709 			descend = 0;
710 			cderrno = errno;
711 		} else
712 			descend = 1;
713 	} else
714 		descend = 0;
715 
716 	/*
717 	 * Figure out the max file name length that can be stored in the
718 	 * current path -- the inner loop allocates more path as necessary.
719 	 * We really wouldn't have to do the maxlen calculations here, we
720 	 * could do them in fts_read before returning the path, but it's a
721 	 * lot easier here since the length is part of the dirent structure.
722 	 *
723 	 * If not changing directories set a pointer so that can just append
724 	 * each new name into the path.
725 	 */
726 	len = NAPPEND(cur);
727 	if (ISSET(FTS_NOCHDIR)) {
728 		cp = sp->fts_path + len;
729 		*cp++ = '/';
730 	} else {
731 		/* GCC, you're too verbose. */
732 		cp = NULL;
733 	}
734 	len++;
735 	maxlen = sp->fts_pathlen - len;
736 
737 	level = cur->fts_level + 1;
738 
739 	/* Read the directory, attaching each entry to the `link' pointer. */
740 	doadjust = 0;
741 	for (head = tail = NULL, nitems = 0; dirp && (dp = readdir(dirp));) {
742 		dnamlen = dp->d_namlen;
743 		if (!ISSET(FTS_SEEDOT) && ISDOT(dp->d_name))
744 			continue;
745 
746 		if ((p = fts_alloc(sp, dp->d_name, (int)dnamlen)) == NULL)
747 			goto mem1;
748 		if (dnamlen >= maxlen) {	/* include space for NUL */
749 			oldaddr = sp->fts_path;
750 			if (fts_palloc(sp, dnamlen + len + 1)) {
751 				/*
752 				 * No more memory for path or structures.  Save
753 				 * errno, free up the current structure and the
754 				 * structures already allocated.
755 				 */
756 mem1:				saved_errno = errno;
757 				if (p)
758 					free(p);
759 				fts_lfree(head);
760 				(void)closedir(dirp);
761 				cur->fts_info = FTS_ERR;
762 				SET(FTS_STOP);
763 				errno = saved_errno;
764 				return (NULL);
765 			}
766 			/* Did realloc() change the pointer? */
767 			if (oldaddr != sp->fts_path) {
768 				doadjust = 1;
769 				if (ISSET(FTS_NOCHDIR))
770 					cp = sp->fts_path + len;
771 			}
772 			maxlen = sp->fts_pathlen - len;
773 		}
774 
775 		if (len + dnamlen >= USHRT_MAX) {
776 			/*
777 			 * In an FTSENT, fts_pathlen is a u_short so it is
778 			 * possible to wraparound here.  If we do, free up
779 			 * the current structure and the structures already
780 			 * allocated, then error out with ENAMETOOLONG.
781 			 */
782 			free(p);
783 			fts_lfree(head);
784 			(void)closedir(dirp);
785 			cur->fts_info = FTS_ERR;
786 			SET(FTS_STOP);
787 			errno = ENAMETOOLONG;
788 			return (NULL);
789 		}
790 		p->fts_level = level;
791 		p->fts_parent = sp->fts_cur;
792 		p->fts_pathlen = len + dnamlen;
793 
794 #ifdef FTS_WHITEOUT
795 		if (dp->d_type == DT_WHT)
796 			p->fts_flags |= FTS_ISW;
797 #endif
798 
799 		if (cderrno) {
800 			if (nlinks) {
801 				p->fts_info = FTS_NS;
802 				p->fts_errno = cderrno;
803 			} else
804 				p->fts_info = FTS_NSOK;
805 			p->fts_accpath = cur->fts_accpath;
806 		} else if (nlinks == 0
807 #ifdef DT_DIR
808 		    || (nostat &&
809 		    dp->d_type != DT_DIR && dp->d_type != DT_UNKNOWN)
810 #endif
811 		    ) {
812 			p->fts_accpath =
813 			    ISSET(FTS_NOCHDIR) ? p->fts_path : p->fts_name;
814 			p->fts_info = FTS_NSOK;
815 		} else {
816 			/* Build a file name for fts_stat to stat. */
817 			if (ISSET(FTS_NOCHDIR)) {
818 				p->fts_accpath = p->fts_path;
819 				memmove(cp, p->fts_name, p->fts_namelen + 1);
820 			} else
821 				p->fts_accpath = p->fts_name;
822 			/* Stat it. */
823 			p->fts_info = fts_stat(sp, p, 0);
824 
825 			/* Decrement link count if applicable. */
826 			if (nlinks > 0 && (p->fts_info == FTS_D ||
827 			    p->fts_info == FTS_DC || p->fts_info == FTS_DOT))
828 				--nlinks;
829 		}
830 
831 		/* We walk in directory order so "ls -f" doesn't get upset. */
832 		p->fts_link = NULL;
833 		if (head == NULL)
834 			head = tail = p;
835 		else {
836 			tail->fts_link = p;
837 			tail = p;
838 		}
839 		++nitems;
840 	}
841 	if (dirp)
842 		(void)closedir(dirp);
843 
844 	/*
845 	 * If realloc() changed the address of the path, adjust the
846 	 * addresses for the rest of the tree and the dir list.
847 	 */
848 	if (doadjust)
849 		fts_padjust(sp, head);
850 
851 	/*
852 	 * If not changing directories, reset the path back to original
853 	 * state.
854 	 */
855 	if (ISSET(FTS_NOCHDIR)) {
856 		if (len == sp->fts_pathlen || nitems == 0)
857 			--cp;
858 		*cp = '\0';
859 	}
860 
861 	/*
862 	 * If descended after called from fts_children or after called from
863 	 * fts_read and nothing found, get back.  At the root level we use
864 	 * the saved fd; if one of fts_open()'s arguments is a relative path
865 	 * to an empty directory, we wind up here with no other way back.  If
866 	 * can't get back, we're done.
867 	 */
868 	if (descend && (type == BCHILD || !nitems) &&
869 	    (cur->fts_level == FTS_ROOTLEVEL ?
870 	    FCHDIR(sp, sp->fts_rfd) :
871 	    fts_safe_changedir(sp, cur->fts_parent, -1, ".."))) {
872 		cur->fts_info = FTS_ERR;
873 		SET(FTS_STOP);
874 		return (NULL);
875 	}
876 
877 	/* If didn't find anything, return NULL. */
878 	if (!nitems) {
879 		if (type == BREAD)
880 			cur->fts_info = FTS_DP;
881 		return (NULL);
882 	}
883 
884 	/* Sort the entries. */
885 	if (sp->fts_compar && nitems > 1)
886 		head = fts_sort(sp, head, nitems);
887 	return (head);
888 }
889 
890 static u_short
891 fts_stat(FTS *sp, FTSENT *p, int follow)
892 {
893 	FTSENT *t;
894 	dev_t dev;
895 	ino_t ino;
896 	struct stat *sbp, sb;
897 	int saved_errno;
898 
899 	/* If user needs stat info, stat buffer already allocated. */
900 	sbp = ISSET(FTS_NOSTAT) ? &sb : p->fts_statp;
901 
902 #ifdef FTS_WHITEOUT
903 	/* Check for whiteout. */
904 	if (p->fts_flags & FTS_ISW) {
905 		if (sbp != &sb) {
906 			memset(sbp, '\0', sizeof(*sbp));
907 			sbp->st_mode = S_IFWHT;
908 		}
909 		return (FTS_W);
910 	}
911 #endif
912 
913 	/*
914 	 * If doing a logical walk, or application requested FTS_FOLLOW, do
915 	 * a stat(2).  If that fails, check for a non-existent symlink.  If
916 	 * fail, set the errno from the stat call.
917 	 */
918 	if (ISSET(FTS_LOGICAL) || follow) {
919 		if (stat(p->fts_accpath, sbp)) {
920 			saved_errno = errno;
921 			if (!lstat(p->fts_accpath, sbp)) {
922 				errno = 0;
923 				return (FTS_SLNONE);
924 			}
925 			p->fts_errno = saved_errno;
926 			goto err;
927 		}
928 	} else if (lstat(p->fts_accpath, sbp)) {
929 		p->fts_errno = errno;
930 err:		memset(sbp, 0, sizeof(struct stat));
931 		return (FTS_NS);
932 	}
933 
934 	if (S_ISDIR(sbp->st_mode)) {
935 		/*
936 		 * Set the device/inode.  Used to find cycles and check for
937 		 * crossing mount points.  Also remember the link count, used
938 		 * in fts_build to limit the number of stat calls.  It is
939 		 * understood that these fields are only referenced if fts_info
940 		 * is set to FTS_D.
941 		 */
942 		dev = p->fts_dev = sbp->st_dev;
943 		ino = p->fts_ino = sbp->st_ino;
944 		p->fts_nlink = sbp->st_nlink;
945 
946 		if (ISDOT(p->fts_name))
947 			return (FTS_DOT);
948 
949 		/*
950 		 * Cycle detection is done by brute force when the directory
951 		 * is first encountered.  If the tree gets deep enough or the
952 		 * number of symbolic links to directories is high enough,
953 		 * something faster might be worthwhile.
954 		 */
955 		for (t = p->fts_parent;
956 		    t->fts_level >= FTS_ROOTLEVEL; t = t->fts_parent)
957 			if (ino == t->fts_ino && dev == t->fts_dev) {
958 				p->fts_cycle = t;
959 				return (FTS_DC);
960 			}
961 		return (FTS_D);
962 	}
963 	if (S_ISLNK(sbp->st_mode))
964 		return (FTS_SL);
965 	if (S_ISREG(sbp->st_mode))
966 		return (FTS_F);
967 	return (FTS_DEFAULT);
968 }
969 
970 /*
971  * The comparison function takes pointers to pointers to FTSENT structures.
972  * Qsort wants a comparison function that takes pointers to void.
973  * (Both with appropriate levels of const-poisoning, of course!)
974  * Use a trampoline function to deal with the difference.
975  */
976 static int
977 fts_compar(const void *a, const void *b)
978 {
979 	FTS *parent;
980 
981 	parent = (*(const FTSENT * const *)a)->fts_fts;
982 	return (*parent->fts_compar)(a, b);
983 }
984 
985 static FTSENT *
986 fts_sort(FTS *sp, FTSENT *head, int nitems)
987 {
988 	FTSENT **ap, *p;
989 
990 	/*
991 	 * Construct an array of pointers to the structures and call qsort(3).
992 	 * Reassemble the array in the order returned by qsort.  If unable to
993 	 * sort for memory reasons, return the directory entries in their
994 	 * current order.  Allocate enough space for the current needs plus
995 	 * 40 so don't realloc one entry at a time.
996 	 */
997 	if (nitems > sp->fts_nitems) {
998 		sp->fts_nitems = nitems + 40;
999 		if ((sp->fts_array = reallocf(sp->fts_array,
1000 		    sp->fts_nitems * sizeof(FTSENT *))) == NULL) {
1001 			sp->fts_nitems = 0;
1002 			return (head);
1003 		}
1004 	}
1005 	for (ap = sp->fts_array, p = head; p; p = p->fts_link)
1006 		*ap++ = p;
1007 	qsort(sp->fts_array, nitems, sizeof(FTSENT *), fts_compar);
1008 	for (head = *(ap = sp->fts_array); --nitems; ++ap)
1009 		ap[0]->fts_link = ap[1];
1010 	ap[0]->fts_link = NULL;
1011 	return (head);
1012 }
1013 
1014 static FTSENT *
1015 fts_alloc(FTS *sp, char *name, int namelen)
1016 {
1017 	FTSENT *p;
1018 	size_t len;
1019 
1020 	struct ftsent_withstat {
1021 		FTSENT	ent;
1022 		struct	stat statbuf;
1023 	};
1024 
1025 	/*
1026 	 * The file name is a variable length array and no stat structure is
1027 	 * necessary if the user has set the nostat bit.  Allocate the FTSENT
1028 	 * structure, the file name and the stat structure in one chunk, but
1029 	 * be careful that the stat structure is reasonably aligned.
1030 	 */
1031 	if (ISSET(FTS_NOSTAT))
1032 		len = sizeof(FTSENT) + namelen + 1;
1033 	else
1034 		len = sizeof(struct ftsent_withstat) + namelen + 1;
1035 
1036 	if ((p = malloc(len)) == NULL)
1037 		return (NULL);
1038 
1039 	if (ISSET(FTS_NOSTAT)) {
1040 		p->fts_name = (char *)(p + 1);
1041 		p->fts_statp = NULL;
1042 	} else {
1043 		p->fts_name = (char *)((struct ftsent_withstat *)p + 1);
1044 		p->fts_statp = &((struct ftsent_withstat *)p)->statbuf;
1045 	}
1046 
1047 	/* Copy the name and guarantee NUL termination. */
1048 	memcpy(p->fts_name, name, namelen);
1049 	p->fts_name[namelen] = '\0';
1050 	p->fts_namelen = namelen;
1051 	p->fts_path = sp->fts_path;
1052 	p->fts_errno = 0;
1053 	p->fts_flags = 0;
1054 	p->fts_instr = FTS_NOINSTR;
1055 	p->fts_number = 0;
1056 	p->fts_pointer = NULL;
1057 	p->fts_fts = sp;
1058 	return (p);
1059 }
1060 
1061 static void
1062 fts_lfree(FTSENT *head)
1063 {
1064 	FTSENT *p;
1065 
1066 	/* Free a linked list of structures. */
1067 	while ((p = head)) {
1068 		head = head->fts_link;
1069 		free(p);
1070 	}
1071 }
1072 
1073 /*
1074  * Allow essentially unlimited paths; find, rm, ls should all work on any tree.
1075  * Most systems will allow creation of paths much longer than MAXPATHLEN, even
1076  * though the kernel won't resolve them.  Add the size (not just what's needed)
1077  * plus 256 bytes so don't realloc the path 2 bytes at a time.
1078  */
1079 static int
1080 fts_palloc(FTS *sp, size_t more)
1081 {
1082 
1083 	sp->fts_pathlen += more + 256;
1084 	/*
1085 	 * Check for possible wraparound.  In an FTS, fts_pathlen is
1086 	 * a signed int but in an FTSENT it is an unsigned short.
1087 	 * We limit fts_pathlen to USHRT_MAX to be safe in both cases.
1088 	 */
1089 	if (sp->fts_pathlen < 0 || sp->fts_pathlen >= USHRT_MAX) {
1090 		if (sp->fts_path)
1091 			free(sp->fts_path);
1092 		sp->fts_path = NULL;
1093 		errno = ENAMETOOLONG;
1094 		return (1);
1095 	}
1096 	sp->fts_path = reallocf(sp->fts_path, sp->fts_pathlen);
1097 	return (sp->fts_path == NULL);
1098 }
1099 
1100 /*
1101  * When the path is realloc'd, have to fix all of the pointers in structures
1102  * already returned.
1103  */
1104 static void
1105 fts_padjust(FTS *sp, FTSENT *head)
1106 {
1107 	FTSENT *p;
1108 	char *addr = sp->fts_path;
1109 
1110 #define	ADJUST(p) do {							\
1111 	if ((p)->fts_accpath != (p)->fts_name) {			\
1112 		(p)->fts_accpath =					\
1113 		    (char *)addr + ((p)->fts_accpath - (p)->fts_path);	\
1114 	}								\
1115 	(p)->fts_path = addr;						\
1116 } while (0)
1117 	/* Adjust the current set of children. */
1118 	for (p = sp->fts_child; p; p = p->fts_link)
1119 		ADJUST(p);
1120 
1121 	/* Adjust the rest of the tree, including the current level. */
1122 	for (p = head; p->fts_level >= FTS_ROOTLEVEL;) {
1123 		ADJUST(p);
1124 		p = p->fts_link ? p->fts_link : p->fts_parent;
1125 	}
1126 }
1127 
1128 static size_t
1129 fts_maxarglen(char * const *argv)
1130 {
1131 	size_t len, max;
1132 
1133 	for (max = 0; *argv; ++argv)
1134 		if ((len = strlen(*argv)) > max)
1135 			max = len;
1136 	return (max + 1);
1137 }
1138 
1139 /*
1140  * Change to dir specified by fd or p->fts_accpath without getting
1141  * tricked by someone changing the world out from underneath us.
1142  * Assumes p->fts_dev and p->fts_ino are filled in.
1143  */
1144 static int
1145 fts_safe_changedir(FTS *sp, FTSENT *p, int fd, char *path)
1146 {
1147 	int ret, oerrno, newfd;
1148 	struct stat sb;
1149 
1150 	newfd = fd;
1151 	if (ISSET(FTS_NOCHDIR))
1152 		return (0);
1153 	if (fd < 0 && (newfd = _open(path, O_RDONLY | O_CLOEXEC, 0)) < 0)
1154 		return (-1);
1155 	if (_fstat(newfd, &sb)) {
1156 		ret = -1;
1157 		goto bail;
1158 	}
1159 	if (p->fts_dev != sb.st_dev || p->fts_ino != sb.st_ino) {
1160 		errno = ENOENT;		/* disinformation */
1161 		ret = -1;
1162 		goto bail;
1163 	}
1164 	ret = fchdir(newfd);
1165 bail:
1166 	oerrno = errno;
1167 	if (fd < 0)
1168 		(void)_close(newfd);
1169 	errno = oerrno;
1170 	return (ret);
1171 }
1172 
1173 /*
1174  * Check if the filesystem for "ent" has UFS-style links.
1175  */
1176 static int
1177 fts_ufslinks(FTS *sp, const FTSENT *ent)
1178 {
1179 	struct _fts_private *priv;
1180 	const char **cpp;
1181 
1182 	priv = (struct _fts_private *)sp;
1183 	/*
1184 	 * If this node's device is different from the previous, grab
1185 	 * the filesystem information, and decide on the reliability
1186 	 * of the link information from this filesystem for stat(2)
1187 	 * avoidance.
1188 	 */
1189 	if (priv->ftsp_dev != ent->fts_dev) {
1190 		if (statfs(ent->fts_path, &priv->ftsp_statfs) != -1) {
1191 			priv->ftsp_dev = ent->fts_dev;
1192 			priv->ftsp_linksreliable = 0;
1193 			for (cpp = ufslike_filesystems; *cpp; cpp++) {
1194 				if (strcmp(priv->ftsp_statfs.f_fstypename,
1195 				    *cpp) == 0) {
1196 					priv->ftsp_linksreliable = 1;
1197 					break;
1198 				}
1199 			}
1200 		} else {
1201 			priv->ftsp_linksreliable = 0;
1202 		}
1203 	}
1204 	return (priv->ftsp_linksreliable);
1205 }
1206 
1207 __sym_compat(fts_open, __fts_open_44bsd, FBSD_1.0);
1208 __sym_compat(fts_close, __fts_close_44bsd, FBSD_1.0);
1209 __sym_compat(fts_read, __fts_read_44bsd, FBSD_1.0);
1210 __sym_compat(fts_set, __fts_set_44bsd, FBSD_1.0);
1211 __sym_compat(fts_children, __fts_children_44bsd, FBSD_1.0);
1212 __sym_compat(fts_get_clientptr, __fts_get_clientptr_44bsd, FBSD_1.0);
1213 __sym_compat(fts_get_stream, __fts_get_stream_44bsd, FBSD_1.0);
1214 __sym_compat(fts_set_clientptr, __fts_set_clientptr_44bsd, FBSD_1.0);
1215