xref: /freebsd/lib/libc/gen/fts.c (revision 7453645f2a9411a3f9d982b768bcc323f41cf906)
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  * 4. 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 <fts.h>
50 #include <stdlib.h>
51 #include <string.h>
52 #include <unistd.h>
53 #include "un-namespace.h"
54 
55 #include "gen-private.h"
56 
57 static FTSENT	*fts_alloc(FTS *, char *, size_t);
58 static FTSENT	*fts_build(FTS *, int);
59 static void	 fts_lfree(FTSENT *);
60 static void	 fts_load(FTS *, FTSENT *);
61 static size_t	 fts_maxarglen(char * const *);
62 static void	 fts_padjust(FTS *, FTSENT *);
63 static int	 fts_palloc(FTS *, size_t);
64 static FTSENT	*fts_sort(FTS *, FTSENT *, size_t);
65 static int	 fts_stat(FTS *, FTSENT *, int, int);
66 static int	 fts_safe_changedir(FTS *, FTSENT *, int, char *);
67 static int	 fts_ufslinks(FTS *, const FTSENT *);
68 
69 #define	ISDOT(a)	(a[0] == '.' && (!a[1] || (a[1] == '.' && !a[2])))
70 
71 #define	CLR(opt)	(sp->fts_options &= ~(opt))
72 #define	ISSET(opt)	(sp->fts_options & (opt))
73 #define	SET(opt)	(sp->fts_options |= (opt))
74 
75 #define	FCHDIR(sp, fd)	(!ISSET(FTS_NOCHDIR) && fchdir(fd))
76 
77 /* fts_build flags */
78 #define	BCHILD		1		/* fts_children */
79 #define	BNAMES		2		/* fts_children, names only */
80 #define	BREAD		3		/* fts_read */
81 
82 /*
83  * Internal representation of an FTS, including extra implementation
84  * details.  The FTS returned from fts_open points to this structure's
85  * ftsp_fts member (and can be cast to an _fts_private as required)
86  */
87 struct _fts_private {
88 	FTS		ftsp_fts;
89 	struct statfs	ftsp_statfs;
90 	dev_t		ftsp_dev;
91 	int		ftsp_linksreliable;
92 };
93 
94 /*
95  * The "FTS_NOSTAT" option can avoid a lot of calls to stat(2) if it
96  * knows that a directory could not possibly have subdirectories.  This
97  * is decided by looking at the link count: a subdirectory would
98  * increment its parent's link count by virtue of its own ".." entry.
99  * This assumption only holds for UFS-like filesystems that implement
100  * links and directories this way, so we must punt for others.
101  */
102 
103 static const char *ufslike_filesystems[] = {
104 	"ufs",
105 	"zfs",
106 	"nfs",
107 	"ext2fs",
108 	0
109 };
110 
111 FTS *
112 fts_open(char * const *argv, int options,
113     int (*compar)(const FTSENT * const *, const FTSENT * const *))
114 {
115 	struct _fts_private *priv;
116 	FTS *sp;
117 	FTSENT *p, *root;
118 	FTSENT *parent, *tmp;
119 	size_t len, nitems;
120 
121 	/* Options check. */
122 	if (options & ~FTS_OPTIONMASK) {
123 		errno = EINVAL;
124 		return (NULL);
125 	}
126 
127 	/* fts_open() requires at least one path */
128 	if (*argv == NULL) {
129 		errno = EINVAL;
130 		return (NULL);
131 	}
132 
133 	/* Allocate/initialize the stream. */
134 	if ((priv = calloc(1, sizeof(*priv))) == NULL)
135 		return (NULL);
136 	sp = &priv->ftsp_fts;
137 	sp->fts_compar = compar;
138 	sp->fts_options = options;
139 
140 	/* Shush, GCC. */
141 	tmp = NULL;
142 
143 	/* Logical walks turn on NOCHDIR; symbolic links are too hard. */
144 	if (ISSET(FTS_LOGICAL))
145 		SET(FTS_NOCHDIR);
146 
147 	/*
148 	 * Start out with 1K of path space, and enough, in any case,
149 	 * to hold the user's paths.
150 	 */
151 	if (fts_palloc(sp, MAX(fts_maxarglen(argv), MAXPATHLEN)))
152 		goto mem1;
153 
154 	/* Allocate/initialize root's parent. */
155 	if ((parent = fts_alloc(sp, "", 0)) == NULL)
156 		goto mem2;
157 	parent->fts_level = FTS_ROOTPARENTLEVEL;
158 
159 	/* Allocate/initialize root(s). */
160 	for (root = NULL, nitems = 0; *argv != NULL; ++argv, ++nitems) {
161 		len = strlen(*argv);
162 
163 		p = fts_alloc(sp, *argv, len);
164 		p->fts_level = FTS_ROOTLEVEL;
165 		p->fts_parent = parent;
166 		p->fts_accpath = p->fts_name;
167 		p->fts_info = fts_stat(sp, p, ISSET(FTS_COMFOLLOW), -1);
168 
169 		/* Command-line "." and ".." are real directories. */
170 		if (p->fts_info == FTS_DOT)
171 			p->fts_info = FTS_D;
172 
173 		/*
174 		 * If comparison routine supplied, traverse in sorted
175 		 * order; otherwise traverse in the order specified.
176 		 */
177 		if (compar) {
178 			p->fts_link = root;
179 			root = p;
180 		} else {
181 			p->fts_link = NULL;
182 			if (root == NULL)
183 				tmp = root = p;
184 			else {
185 				tmp->fts_link = p;
186 				tmp = p;
187 			}
188 		}
189 	}
190 	if (compar && nitems > 1)
191 		root = fts_sort(sp, root, nitems);
192 
193 	/*
194 	 * Allocate a dummy pointer and make fts_read think that we've just
195 	 * finished the node before the root(s); set p->fts_info to FTS_INIT
196 	 * so that everything about the "current" node is ignored.
197 	 */
198 	if ((sp->fts_cur = fts_alloc(sp, "", 0)) == NULL)
199 		goto mem3;
200 	sp->fts_cur->fts_link = root;
201 	sp->fts_cur->fts_info = FTS_INIT;
202 
203 	/*
204 	 * If using chdir(2), grab a file descriptor pointing to dot to ensure
205 	 * that we can get back here; this could be avoided for some paths,
206 	 * but almost certainly not worth the effort.  Slashes, symbolic links,
207 	 * and ".." are all fairly nasty problems.  Note, if we can't get the
208 	 * descriptor we run anyway, just more slowly.
209 	 */
210 	if (!ISSET(FTS_NOCHDIR) &&
211 	    (sp->fts_rfd = _open(".", O_RDONLY | O_CLOEXEC, 0)) < 0)
212 		SET(FTS_NOCHDIR);
213 
214 	return (sp);
215 
216 mem3:	fts_lfree(root);
217 	free(parent);
218 mem2:	free(sp->fts_path);
219 mem1:	free(sp);
220 	return (NULL);
221 }
222 
223 static void
224 fts_load(FTS *sp, FTSENT *p)
225 {
226 	size_t len;
227 	char *cp;
228 
229 	/*
230 	 * Load the stream structure for the next traversal.  Since we don't
231 	 * actually enter the directory until after the preorder visit, set
232 	 * the fts_accpath field specially so the chdir gets done to the right
233 	 * place and the user can access the first node.  From fts_open it's
234 	 * known that the path will fit.
235 	 */
236 	len = p->fts_pathlen = p->fts_namelen;
237 	memmove(sp->fts_path, p->fts_name, len + 1);
238 	if ((cp = strrchr(p->fts_name, '/')) && (cp != p->fts_name || cp[1])) {
239 		len = strlen(++cp);
240 		memmove(p->fts_name, cp, len + 1);
241 		p->fts_namelen = len;
242 	}
243 	p->fts_accpath = p->fts_path = sp->fts_path;
244 	sp->fts_dev = p->fts_dev;
245 }
246 
247 int
248 fts_close(FTS *sp)
249 {
250 	FTSENT *freep, *p;
251 	int saved_errno;
252 
253 	/*
254 	 * This still works if we haven't read anything -- the dummy structure
255 	 * points to the root list, so we step through to the end of the root
256 	 * list which has a valid parent pointer.
257 	 */
258 	if (sp->fts_cur) {
259 		for (p = sp->fts_cur; p->fts_level >= FTS_ROOTLEVEL;) {
260 			freep = p;
261 			p = p->fts_link != NULL ? p->fts_link : p->fts_parent;
262 			free(freep);
263 		}
264 		free(p);
265 	}
266 
267 	/* Free up child linked list, sort array, path buffer. */
268 	if (sp->fts_child)
269 		fts_lfree(sp->fts_child);
270 	if (sp->fts_array)
271 		free(sp->fts_array);
272 	free(sp->fts_path);
273 
274 	/* Return to original directory, save errno if necessary. */
275 	if (!ISSET(FTS_NOCHDIR)) {
276 		saved_errno = fchdir(sp->fts_rfd) ? errno : 0;
277 		(void)_close(sp->fts_rfd);
278 
279 		/* Set errno and return. */
280 		if (saved_errno != 0) {
281 			/* Free up the stream pointer. */
282 			free(sp);
283 			errno = saved_errno;
284 			return (-1);
285 		}
286 	}
287 
288 	/* Free up the stream pointer. */
289 	free(sp);
290 	return (0);
291 }
292 
293 /*
294  * Special case of "/" at the end of the path so that slashes aren't
295  * appended which would cause paths to be written as "....//foo".
296  */
297 #define	NAPPEND(p)							\
298 	(p->fts_path[p->fts_pathlen - 1] == '/'				\
299 	    ? p->fts_pathlen - 1 : p->fts_pathlen)
300 
301 FTSENT *
302 fts_read(FTS *sp)
303 {
304 	FTSENT *p, *tmp;
305 	int instr;
306 	char *t;
307 	int saved_errno;
308 
309 	/* If finished or unrecoverable error, return NULL. */
310 	if (sp->fts_cur == NULL || ISSET(FTS_STOP))
311 		return (NULL);
312 
313 	/* Set current node pointer. */
314 	p = sp->fts_cur;
315 
316 	/* Save and zero out user instructions. */
317 	instr = p->fts_instr;
318 	p->fts_instr = FTS_NOINSTR;
319 
320 	/* Any type of file may be re-visited; re-stat and re-turn. */
321 	if (instr == FTS_AGAIN) {
322 		p->fts_info = fts_stat(sp, p, 0, -1);
323 		return (p);
324 	}
325 
326 	/*
327 	 * Following a symlink -- SLNONE test allows application to see
328 	 * SLNONE and recover.  If indirecting through a symlink, have
329 	 * keep a pointer to current location.  If unable to get that
330 	 * pointer, follow fails.
331 	 */
332 	if (instr == FTS_FOLLOW &&
333 	    (p->fts_info == FTS_SL || p->fts_info == FTS_SLNONE)) {
334 		p->fts_info = fts_stat(sp, p, 1, -1);
335 		if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {
336 			if ((p->fts_symfd = _open(".", O_RDONLY | O_CLOEXEC,
337 			    0)) < 0) {
338 				p->fts_errno = errno;
339 				p->fts_info = FTS_ERR;
340 			} else
341 				p->fts_flags |= FTS_SYMFOLLOW;
342 		}
343 		return (p);
344 	}
345 
346 	/* Directory in pre-order. */
347 	if (p->fts_info == FTS_D) {
348 		/* If skipped or crossed mount point, do post-order visit. */
349 		if (instr == FTS_SKIP ||
350 		    (ISSET(FTS_XDEV) && p->fts_dev != sp->fts_dev)) {
351 			if (p->fts_flags & FTS_SYMFOLLOW)
352 				(void)_close(p->fts_symfd);
353 			if (sp->fts_child) {
354 				fts_lfree(sp->fts_child);
355 				sp->fts_child = NULL;
356 			}
357 			p->fts_info = FTS_DP;
358 			return (p);
359 		}
360 
361 		/* Rebuild if only read the names and now traversing. */
362 		if (sp->fts_child != NULL && ISSET(FTS_NAMEONLY)) {
363 			CLR(FTS_NAMEONLY);
364 			fts_lfree(sp->fts_child);
365 			sp->fts_child = NULL;
366 		}
367 
368 		/*
369 		 * Cd to the subdirectory.
370 		 *
371 		 * If have already read and now fail to chdir, whack the list
372 		 * to make the names come out right, and set the parent errno
373 		 * so the application will eventually get an error condition.
374 		 * Set the FTS_DONTCHDIR flag so that when we logically change
375 		 * directories back to the parent we don't do a chdir.
376 		 *
377 		 * If haven't read do so.  If the read fails, fts_build sets
378 		 * FTS_STOP or the fts_info field of the node.
379 		 */
380 		if (sp->fts_child != NULL) {
381 			if (fts_safe_changedir(sp, p, -1, p->fts_accpath)) {
382 				p->fts_errno = errno;
383 				p->fts_flags |= FTS_DONTCHDIR;
384 				for (p = sp->fts_child; p != NULL;
385 				    p = p->fts_link)
386 					p->fts_accpath =
387 					    p->fts_parent->fts_accpath;
388 			}
389 		} else if ((sp->fts_child = fts_build(sp, BREAD)) == NULL) {
390 			if (ISSET(FTS_STOP))
391 				return (NULL);
392 			return (p);
393 		}
394 		p = sp->fts_child;
395 		sp->fts_child = NULL;
396 		goto name;
397 	}
398 
399 	/* Move to the next node on this level. */
400 next:	tmp = p;
401 	if ((p = p->fts_link) != NULL) {
402 		/*
403 		 * If reached the top, return to the original directory (or
404 		 * the root of the tree), and load the paths for the next root.
405 		 */
406 		if (p->fts_level == FTS_ROOTLEVEL) {
407 			if (FCHDIR(sp, sp->fts_rfd)) {
408 				SET(FTS_STOP);
409 				return (NULL);
410 			}
411 			free(tmp);
412 			fts_load(sp, p);
413 			return (sp->fts_cur = p);
414 		}
415 
416 		/*
417 		 * User may have called fts_set on the node.  If skipped,
418 		 * ignore.  If followed, get a file descriptor so we can
419 		 * get back if necessary.
420 		 */
421 		if (p->fts_instr == FTS_SKIP) {
422 			free(tmp);
423 			goto next;
424 		}
425 		if (p->fts_instr == FTS_FOLLOW) {
426 			p->fts_info = fts_stat(sp, p, 1, -1);
427 			if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {
428 				if ((p->fts_symfd =
429 				    _open(".", O_RDONLY | O_CLOEXEC, 0)) < 0) {
430 					p->fts_errno = errno;
431 					p->fts_info = FTS_ERR;
432 				} else
433 					p->fts_flags |= FTS_SYMFOLLOW;
434 			}
435 			p->fts_instr = FTS_NOINSTR;
436 		}
437 
438 		free(tmp);
439 
440 name:		t = sp->fts_path + NAPPEND(p->fts_parent);
441 		*t++ = '/';
442 		memmove(t, p->fts_name, p->fts_namelen + 1);
443 		return (sp->fts_cur = p);
444 	}
445 
446 	/* Move up to the parent node. */
447 	p = tmp->fts_parent;
448 
449 	if (p->fts_level == FTS_ROOTPARENTLEVEL) {
450 		/*
451 		 * Done; free everything up and set errno to 0 so the user
452 		 * can distinguish between error and EOF.
453 		 */
454 		free(tmp);
455 		free(p);
456 		errno = 0;
457 		return (sp->fts_cur = NULL);
458 	}
459 
460 	/* NUL terminate the pathname. */
461 	sp->fts_path[p->fts_pathlen] = '\0';
462 
463 	/*
464 	 * Return to the parent directory.  If at a root node or came through
465 	 * a symlink, go back through the file descriptor.  Otherwise, cd up
466 	 * one directory.
467 	 */
468 	if (p->fts_level == FTS_ROOTLEVEL) {
469 		if (FCHDIR(sp, sp->fts_rfd)) {
470 			SET(FTS_STOP);
471 			return (NULL);
472 		}
473 	} else if (p->fts_flags & FTS_SYMFOLLOW) {
474 		if (FCHDIR(sp, p->fts_symfd)) {
475 			saved_errno = errno;
476 			(void)_close(p->fts_symfd);
477 			errno = saved_errno;
478 			SET(FTS_STOP);
479 			return (NULL);
480 		}
481 		(void)_close(p->fts_symfd);
482 	} else if (!(p->fts_flags & FTS_DONTCHDIR) &&
483 	    fts_safe_changedir(sp, p->fts_parent, -1, "..")) {
484 		SET(FTS_STOP);
485 		return (NULL);
486 	}
487 	free(tmp);
488 	p->fts_info = p->fts_errno ? FTS_ERR : FTS_DP;
489 	return (sp->fts_cur = p);
490 }
491 
492 /*
493  * Fts_set takes the stream as an argument although it's not used in this
494  * implementation; it would be necessary if anyone wanted to add global
495  * semantics to fts using fts_set.  An error return is allowed for similar
496  * reasons.
497  */
498 /* ARGSUSED */
499 int
500 fts_set(FTS *sp, FTSENT *p, int instr)
501 {
502 	if (instr != 0 && instr != FTS_AGAIN && instr != FTS_FOLLOW &&
503 	    instr != FTS_NOINSTR && instr != FTS_SKIP) {
504 		errno = EINVAL;
505 		return (1);
506 	}
507 	p->fts_instr = instr;
508 	return (0);
509 }
510 
511 FTSENT *
512 fts_children(FTS *sp, int instr)
513 {
514 	FTSENT *p;
515 	int fd, rc, serrno;
516 
517 	if (instr != 0 && instr != FTS_NAMEONLY) {
518 		errno = EINVAL;
519 		return (NULL);
520 	}
521 
522 	/* Set current node pointer. */
523 	p = sp->fts_cur;
524 
525 	/*
526 	 * Errno set to 0 so user can distinguish empty directory from
527 	 * an error.
528 	 */
529 	errno = 0;
530 
531 	/* Fatal errors stop here. */
532 	if (ISSET(FTS_STOP))
533 		return (NULL);
534 
535 	/* Return logical hierarchy of user's arguments. */
536 	if (p->fts_info == FTS_INIT)
537 		return (p->fts_link);
538 
539 	/*
540 	 * If not a directory being visited in pre-order, stop here.  Could
541 	 * allow FTS_DNR, assuming the user has fixed the problem, but the
542 	 * same effect is available with FTS_AGAIN.
543 	 */
544 	if (p->fts_info != FTS_D /* && p->fts_info != FTS_DNR */)
545 		return (NULL);
546 
547 	/* Free up any previous child list. */
548 	if (sp->fts_child != NULL)
549 		fts_lfree(sp->fts_child);
550 
551 	if (instr == FTS_NAMEONLY) {
552 		SET(FTS_NAMEONLY);
553 		instr = BNAMES;
554 	} else
555 		instr = BCHILD;
556 
557 	/*
558 	 * If using chdir on a relative path and called BEFORE fts_read does
559 	 * its chdir to the root of a traversal, we can lose -- we need to
560 	 * chdir into the subdirectory, and we don't know where the current
561 	 * directory is, so we can't get back so that the upcoming chdir by
562 	 * fts_read will work.
563 	 */
564 	if (p->fts_level != FTS_ROOTLEVEL || p->fts_accpath[0] == '/' ||
565 	    ISSET(FTS_NOCHDIR))
566 		return (sp->fts_child = fts_build(sp, instr));
567 
568 	if ((fd = _open(".", O_RDONLY | O_CLOEXEC, 0)) < 0)
569 		return (NULL);
570 	sp->fts_child = fts_build(sp, instr);
571 	serrno = (sp->fts_child == NULL) ? errno : 0;
572 	rc = fchdir(fd);
573 	if (rc < 0 && serrno == 0)
574 		serrno = errno;
575 	(void)_close(fd);
576 	errno = serrno;
577 	if (rc < 0)
578 		return (NULL);
579 	return (sp->fts_child);
580 }
581 
582 #ifndef fts_get_clientptr
583 #error "fts_get_clientptr not defined"
584 #endif
585 
586 void *
587 (fts_get_clientptr)(FTS *sp)
588 {
589 
590 	return (fts_get_clientptr(sp));
591 }
592 
593 #ifndef fts_get_stream
594 #error "fts_get_stream not defined"
595 #endif
596 
597 FTS *
598 (fts_get_stream)(FTSENT *p)
599 {
600 	return (fts_get_stream(p));
601 }
602 
603 void
604 fts_set_clientptr(FTS *sp, void *clientptr)
605 {
606 
607 	sp->fts_clientptr = clientptr;
608 }
609 
610 /*
611  * This is the tricky part -- do not casually change *anything* in here.  The
612  * idea is to build the linked list of entries that are used by fts_children
613  * and fts_read.  There are lots of special cases.
614  *
615  * The real slowdown in walking the tree is the stat calls.  If FTS_NOSTAT is
616  * set and it's a physical walk (so that symbolic links can't be directories),
617  * we can do things quickly.  First, if it's a 4.4BSD file system, the type
618  * of the file is in the directory entry.  Otherwise, we assume that the number
619  * of subdirectories in a node is equal to the number of links to the parent.
620  * The former skips all stat calls.  The latter skips stat calls in any leaf
621  * directories and for any files after the subdirectories in the directory have
622  * been found, cutting the stat calls by about 2/3.
623  */
624 static FTSENT *
625 fts_build(FTS *sp, int type)
626 {
627 	struct dirent *dp;
628 	FTSENT *p, *head;
629 	FTSENT *cur, *tail;
630 	DIR *dirp;
631 	void *oldaddr;
632 	char *cp;
633 	int cderrno, descend, oflag, saved_errno, nostat, doadjust;
634 	long level;
635 	long nlinks;	/* has to be signed because -1 is a magic value */
636 	size_t dnamlen, len, maxlen, nitems;
637 
638 	/* Set current node pointer. */
639 	cur = sp->fts_cur;
640 
641 	/*
642 	 * Open the directory for reading.  If this fails, we're done.
643 	 * If being called from fts_read, set the fts_info field.
644 	 */
645 #ifdef FTS_WHITEOUT
646 	if (ISSET(FTS_WHITEOUT))
647 		oflag = DTF_NODUP | DTF_REWIND;
648 	else
649 		oflag = DTF_HIDEW | DTF_NODUP | DTF_REWIND;
650 #else
651 #define __opendir2(path, flag) opendir(path)
652 #endif
653 	if ((dirp = __opendir2(cur->fts_accpath, oflag)) == NULL) {
654 		if (type == BREAD) {
655 			cur->fts_info = FTS_DNR;
656 			cur->fts_errno = errno;
657 		}
658 		return (NULL);
659 	}
660 
661 	/*
662 	 * Nlinks is the number of possible entries of type directory in the
663 	 * directory if we're cheating on stat calls, 0 if we're not doing
664 	 * any stat calls at all, -1 if we're doing stats on everything.
665 	 */
666 	if (type == BNAMES) {
667 		nlinks = 0;
668 		/* Be quiet about nostat, GCC. */
669 		nostat = 0;
670 	} else if (ISSET(FTS_NOSTAT) && ISSET(FTS_PHYSICAL)) {
671 		if (fts_ufslinks(sp, cur))
672 			nlinks = cur->fts_nlink - (ISSET(FTS_SEEDOT) ? 0 : 2);
673 		else
674 			nlinks = -1;
675 		nostat = 1;
676 	} else {
677 		nlinks = -1;
678 		nostat = 0;
679 	}
680 
681 #ifdef notdef
682 	(void)printf("nlinks == %d (cur: %d)\n", nlinks, cur->fts_nlink);
683 	(void)printf("NOSTAT %d PHYSICAL %d SEEDOT %d\n",
684 	    ISSET(FTS_NOSTAT), ISSET(FTS_PHYSICAL), ISSET(FTS_SEEDOT));
685 #endif
686 	/*
687 	 * If we're going to need to stat anything or we want to descend
688 	 * and stay in the directory, chdir.  If this fails we keep going,
689 	 * but set a flag so we don't chdir after the post-order visit.
690 	 * We won't be able to stat anything, but we can still return the
691 	 * names themselves.  Note, that since fts_read won't be able to
692 	 * chdir into the directory, it will have to return different path
693 	 * names than before, i.e. "a/b" instead of "b".  Since the node
694 	 * has already been visited in pre-order, have to wait until the
695 	 * post-order visit to return the error.  There is a special case
696 	 * here, if there was nothing to stat then it's not an error to
697 	 * not be able to stat.  This is all fairly nasty.  If a program
698 	 * needed sorted entries or stat information, they had better be
699 	 * checking FTS_NS on the returned nodes.
700 	 */
701 	cderrno = 0;
702 	if (nlinks || type == BREAD) {
703 		if (fts_safe_changedir(sp, cur, _dirfd(dirp), NULL)) {
704 			if (nlinks && type == BREAD)
705 				cur->fts_errno = errno;
706 			cur->fts_flags |= FTS_DONTCHDIR;
707 			descend = 0;
708 			cderrno = errno;
709 		} else
710 			descend = 1;
711 	} else
712 		descend = 0;
713 
714 	/*
715 	 * Figure out the max file name length that can be stored in the
716 	 * current path -- the inner loop allocates more path as necessary.
717 	 * We really wouldn't have to do the maxlen calculations here, we
718 	 * could do them in fts_read before returning the path, but it's a
719 	 * lot easier here since the length is part of the dirent structure.
720 	 *
721 	 * If not changing directories set a pointer so that can just append
722 	 * each new name into the path.
723 	 */
724 	len = NAPPEND(cur);
725 	if (ISSET(FTS_NOCHDIR)) {
726 		cp = sp->fts_path + len;
727 		*cp++ = '/';
728 	} else {
729 		/* GCC, you're too verbose. */
730 		cp = NULL;
731 	}
732 	len++;
733 	maxlen = sp->fts_pathlen - len;
734 
735 	level = cur->fts_level + 1;
736 
737 	/* Read the directory, attaching each entry to the `link' pointer. */
738 	doadjust = 0;
739 	for (head = tail = NULL, nitems = 0; dirp && (dp = readdir(dirp));) {
740 		dnamlen = dp->d_namlen;
741 		if (!ISSET(FTS_SEEDOT) && ISDOT(dp->d_name))
742 			continue;
743 
744 		if ((p = fts_alloc(sp, dp->d_name, dnamlen)) == NULL)
745 			goto mem1;
746 		if (dnamlen >= maxlen) {	/* include space for NUL */
747 			oldaddr = sp->fts_path;
748 			if (fts_palloc(sp, dnamlen + len + 1)) {
749 				/*
750 				 * No more memory for path or structures.  Save
751 				 * errno, free up the current structure and the
752 				 * structures already allocated.
753 				 */
754 mem1:				saved_errno = errno;
755 				if (p)
756 					free(p);
757 				fts_lfree(head);
758 				(void)closedir(dirp);
759 				cur->fts_info = FTS_ERR;
760 				SET(FTS_STOP);
761 				errno = saved_errno;
762 				return (NULL);
763 			}
764 			/* Did realloc() change the pointer? */
765 			if (oldaddr != sp->fts_path) {
766 				doadjust = 1;
767 				if (ISSET(FTS_NOCHDIR))
768 					cp = sp->fts_path + len;
769 			}
770 			maxlen = sp->fts_pathlen - len;
771 		}
772 
773 		p->fts_level = level;
774 		p->fts_parent = sp->fts_cur;
775 		p->fts_pathlen = len + dnamlen;
776 
777 #ifdef FTS_WHITEOUT
778 		if (dp->d_type == DT_WHT)
779 			p->fts_flags |= FTS_ISW;
780 #endif
781 
782 		if (cderrno) {
783 			if (nlinks) {
784 				p->fts_info = FTS_NS;
785 				p->fts_errno = cderrno;
786 			} else
787 				p->fts_info = FTS_NSOK;
788 			p->fts_accpath = cur->fts_accpath;
789 		} else if (nlinks == 0
790 #ifdef DT_DIR
791 		    || (nostat &&
792 		    dp->d_type != DT_DIR && dp->d_type != DT_UNKNOWN)
793 #endif
794 		    ) {
795 			p->fts_accpath =
796 			    ISSET(FTS_NOCHDIR) ? p->fts_path : p->fts_name;
797 			p->fts_info = FTS_NSOK;
798 		} else {
799 			/* Build a file name for fts_stat to stat. */
800 			if (ISSET(FTS_NOCHDIR)) {
801 				p->fts_accpath = p->fts_path;
802 				memmove(cp, p->fts_name, p->fts_namelen + 1);
803 				p->fts_info = fts_stat(sp, p, 0, _dirfd(dirp));
804 			} else {
805 				p->fts_accpath = p->fts_name;
806 				p->fts_info = fts_stat(sp, p, 0, -1);
807 			}
808 
809 			/* Decrement link count if applicable. */
810 			if (nlinks > 0 && (p->fts_info == FTS_D ||
811 			    p->fts_info == FTS_DC || p->fts_info == FTS_DOT))
812 				--nlinks;
813 		}
814 
815 		/* We walk in directory order so "ls -f" doesn't get upset. */
816 		p->fts_link = NULL;
817 		if (head == NULL)
818 			head = tail = p;
819 		else {
820 			tail->fts_link = p;
821 			tail = p;
822 		}
823 		++nitems;
824 	}
825 	if (dirp)
826 		(void)closedir(dirp);
827 
828 	/*
829 	 * If realloc() changed the address of the path, adjust the
830 	 * addresses for the rest of the tree and the dir list.
831 	 */
832 	if (doadjust)
833 		fts_padjust(sp, head);
834 
835 	/*
836 	 * If not changing directories, reset the path back to original
837 	 * state.
838 	 */
839 	if (ISSET(FTS_NOCHDIR))
840 		sp->fts_path[cur->fts_pathlen] = '\0';
841 
842 	/*
843 	 * If descended after called from fts_children or after called from
844 	 * fts_read and nothing found, get back.  At the root level we use
845 	 * the saved fd; if one of fts_open()'s arguments is a relative path
846 	 * to an empty directory, we wind up here with no other way back.  If
847 	 * can't get back, we're done.
848 	 */
849 	if (descend && (type == BCHILD || !nitems) &&
850 	    (cur->fts_level == FTS_ROOTLEVEL ?
851 	    FCHDIR(sp, sp->fts_rfd) :
852 	    fts_safe_changedir(sp, cur->fts_parent, -1, ".."))) {
853 		cur->fts_info = FTS_ERR;
854 		SET(FTS_STOP);
855 		return (NULL);
856 	}
857 
858 	/* If didn't find anything, return NULL. */
859 	if (!nitems) {
860 		if (type == BREAD)
861 			cur->fts_info = FTS_DP;
862 		return (NULL);
863 	}
864 
865 	/* Sort the entries. */
866 	if (sp->fts_compar && nitems > 1)
867 		head = fts_sort(sp, head, nitems);
868 	return (head);
869 }
870 
871 static int
872 fts_stat(FTS *sp, FTSENT *p, int follow, int dfd)
873 {
874 	FTSENT *t;
875 	dev_t dev;
876 	ino_t ino;
877 	struct stat *sbp, sb;
878 	int saved_errno;
879 	const char *path;
880 
881 	if (dfd == -1)
882 		path = p->fts_accpath, dfd = AT_FDCWD;
883 	else
884 		path = p->fts_name;
885 
886 	/* If user needs stat info, stat buffer already allocated. */
887 	sbp = ISSET(FTS_NOSTAT) ? &sb : p->fts_statp;
888 
889 #ifdef FTS_WHITEOUT
890 	/* Check for whiteout. */
891 	if (p->fts_flags & FTS_ISW) {
892 		if (sbp != &sb) {
893 			memset(sbp, '\0', sizeof(*sbp));
894 			sbp->st_mode = S_IFWHT;
895 		}
896 		return (FTS_W);
897 	}
898 #endif
899 
900 	/*
901 	 * If doing a logical walk, or application requested FTS_FOLLOW, do
902 	 * a stat(2).  If that fails, check for a non-existent symlink.  If
903 	 * fail, set the errno from the stat call.
904 	 */
905 	if (ISSET(FTS_LOGICAL) || follow) {
906 		if (fstatat(dfd, path, sbp, 0)) {
907 			saved_errno = errno;
908 			if (fstatat(dfd, path, sbp, AT_SYMLINK_NOFOLLOW)) {
909 				p->fts_errno = saved_errno;
910 				goto err;
911 			}
912 			errno = 0;
913 			if (S_ISLNK(sbp->st_mode))
914 				return (FTS_SLNONE);
915 		}
916 	} else if (fstatat(dfd, path, sbp, AT_SYMLINK_NOFOLLOW)) {
917 		p->fts_errno = errno;
918 err:		memset(sbp, 0, sizeof(struct stat));
919 		return (FTS_NS);
920 	}
921 
922 	if (S_ISDIR(sbp->st_mode)) {
923 		/*
924 		 * Set the device/inode.  Used to find cycles and check for
925 		 * crossing mount points.  Also remember the link count, used
926 		 * in fts_build to limit the number of stat calls.  It is
927 		 * understood that these fields are only referenced if fts_info
928 		 * is set to FTS_D.
929 		 */
930 		dev = p->fts_dev = sbp->st_dev;
931 		ino = p->fts_ino = sbp->st_ino;
932 		p->fts_nlink = sbp->st_nlink;
933 
934 		if (ISDOT(p->fts_name))
935 			return (FTS_DOT);
936 
937 		/*
938 		 * Cycle detection is done by brute force when the directory
939 		 * is first encountered.  If the tree gets deep enough or the
940 		 * number of symbolic links to directories is high enough,
941 		 * something faster might be worthwhile.
942 		 */
943 		for (t = p->fts_parent;
944 		    t->fts_level >= FTS_ROOTLEVEL; t = t->fts_parent)
945 			if (ino == t->fts_ino && dev == t->fts_dev) {
946 				p->fts_cycle = t;
947 				return (FTS_DC);
948 			}
949 		return (FTS_D);
950 	}
951 	if (S_ISLNK(sbp->st_mode))
952 		return (FTS_SL);
953 	if (S_ISREG(sbp->st_mode))
954 		return (FTS_F);
955 	return (FTS_DEFAULT);
956 }
957 
958 /*
959  * The comparison function takes pointers to pointers to FTSENT structures.
960  * Qsort wants a comparison function that takes pointers to void.
961  * (Both with appropriate levels of const-poisoning, of course!)
962  * Use a trampoline function to deal with the difference.
963  */
964 static int
965 fts_compar(const void *a, const void *b)
966 {
967 	FTS *parent;
968 
969 	parent = (*(const FTSENT * const *)a)->fts_fts;
970 	return (*parent->fts_compar)(a, b);
971 }
972 
973 static FTSENT *
974 fts_sort(FTS *sp, FTSENT *head, size_t nitems)
975 {
976 	FTSENT **ap, *p;
977 
978 	/*
979 	 * Construct an array of pointers to the structures and call qsort(3).
980 	 * Reassemble the array in the order returned by qsort.  If unable to
981 	 * sort for memory reasons, return the directory entries in their
982 	 * current order.  Allocate enough space for the current needs plus
983 	 * 40 so don't realloc one entry at a time.
984 	 */
985 	if (nitems > sp->fts_nitems) {
986 		sp->fts_nitems = nitems + 40;
987 		if ((sp->fts_array = reallocf(sp->fts_array,
988 		    sp->fts_nitems * sizeof(FTSENT *))) == NULL) {
989 			sp->fts_nitems = 0;
990 			return (head);
991 		}
992 	}
993 	for (ap = sp->fts_array, p = head; p; p = p->fts_link)
994 		*ap++ = p;
995 	qsort(sp->fts_array, nitems, sizeof(FTSENT *), fts_compar);
996 	for (head = *(ap = sp->fts_array); --nitems; ++ap)
997 		ap[0]->fts_link = ap[1];
998 	ap[0]->fts_link = NULL;
999 	return (head);
1000 }
1001 
1002 static FTSENT *
1003 fts_alloc(FTS *sp, char *name, size_t namelen)
1004 {
1005 	FTSENT *p;
1006 	size_t len;
1007 
1008 	struct ftsent_withstat {
1009 		FTSENT	ent;
1010 		struct	stat statbuf;
1011 	};
1012 
1013 	/*
1014 	 * The file name is a variable length array and no stat structure is
1015 	 * necessary if the user has set the nostat bit.  Allocate the FTSENT
1016 	 * structure, the file name and the stat structure in one chunk, but
1017 	 * be careful that the stat structure is reasonably aligned.
1018 	 */
1019 	if (ISSET(FTS_NOSTAT))
1020 		len = sizeof(FTSENT) + namelen + 1;
1021 	else
1022 		len = sizeof(struct ftsent_withstat) + namelen + 1;
1023 
1024 	if ((p = malloc(len)) == NULL)
1025 		return (NULL);
1026 
1027 	if (ISSET(FTS_NOSTAT)) {
1028 		p->fts_name = (char *)(p + 1);
1029 		p->fts_statp = NULL;
1030 	} else {
1031 		p->fts_name = (char *)((struct ftsent_withstat *)p + 1);
1032 		p->fts_statp = &((struct ftsent_withstat *)p)->statbuf;
1033 	}
1034 
1035 	/* Copy the name and guarantee NUL termination. */
1036 	memcpy(p->fts_name, name, namelen);
1037 	p->fts_name[namelen] = '\0';
1038 	p->fts_namelen = namelen;
1039 	p->fts_path = sp->fts_path;
1040 	p->fts_errno = 0;
1041 	p->fts_flags = 0;
1042 	p->fts_instr = FTS_NOINSTR;
1043 	p->fts_number = 0;
1044 	p->fts_pointer = NULL;
1045 	p->fts_fts = sp;
1046 	return (p);
1047 }
1048 
1049 static void
1050 fts_lfree(FTSENT *head)
1051 {
1052 	FTSENT *p;
1053 
1054 	/* Free a linked list of structures. */
1055 	while ((p = head)) {
1056 		head = head->fts_link;
1057 		free(p);
1058 	}
1059 }
1060 
1061 /*
1062  * Allow essentially unlimited paths; find, rm, ls should all work on any tree.
1063  * Most systems will allow creation of paths much longer than MAXPATHLEN, even
1064  * though the kernel won't resolve them.  Add the size (not just what's needed)
1065  * plus 256 bytes so don't realloc the path 2 bytes at a time.
1066  */
1067 static int
1068 fts_palloc(FTS *sp, size_t more)
1069 {
1070 
1071 	sp->fts_pathlen += more + 256;
1072 	sp->fts_path = reallocf(sp->fts_path, sp->fts_pathlen);
1073 	return (sp->fts_path == NULL);
1074 }
1075 
1076 /*
1077  * When the path is realloc'd, have to fix all of the pointers in structures
1078  * already returned.
1079  */
1080 static void
1081 fts_padjust(FTS *sp, FTSENT *head)
1082 {
1083 	FTSENT *p;
1084 	char *addr = sp->fts_path;
1085 
1086 #define	ADJUST(p) do {							\
1087 	if ((p)->fts_accpath != (p)->fts_name) {			\
1088 		(p)->fts_accpath =					\
1089 		    (char *)addr + ((p)->fts_accpath - (p)->fts_path);	\
1090 	}								\
1091 	(p)->fts_path = addr;						\
1092 } while (0)
1093 	/* Adjust the current set of children. */
1094 	for (p = sp->fts_child; p; p = p->fts_link)
1095 		ADJUST(p);
1096 
1097 	/* Adjust the rest of the tree, including the current level. */
1098 	for (p = head; p->fts_level >= FTS_ROOTLEVEL;) {
1099 		ADJUST(p);
1100 		p = p->fts_link ? p->fts_link : p->fts_parent;
1101 	}
1102 }
1103 
1104 static size_t
1105 fts_maxarglen(char * const *argv)
1106 {
1107 	size_t len, max;
1108 
1109 	for (max = 0; *argv; ++argv)
1110 		if ((len = strlen(*argv)) > max)
1111 			max = len;
1112 	return (max + 1);
1113 }
1114 
1115 /*
1116  * Change to dir specified by fd or p->fts_accpath without getting
1117  * tricked by someone changing the world out from underneath us.
1118  * Assumes p->fts_dev and p->fts_ino are filled in.
1119  */
1120 static int
1121 fts_safe_changedir(FTS *sp, FTSENT *p, int fd, char *path)
1122 {
1123 	int ret, oerrno, newfd;
1124 	struct stat sb;
1125 
1126 	newfd = fd;
1127 	if (ISSET(FTS_NOCHDIR))
1128 		return (0);
1129 	if (fd < 0 && (newfd = _open(path, O_RDONLY | O_DIRECTORY |
1130 	    O_CLOEXEC, 0)) < 0)
1131 		return (-1);
1132 	if (_fstat(newfd, &sb)) {
1133 		ret = -1;
1134 		goto bail;
1135 	}
1136 	if (p->fts_dev != sb.st_dev || p->fts_ino != sb.st_ino) {
1137 		errno = ENOENT;		/* disinformation */
1138 		ret = -1;
1139 		goto bail;
1140 	}
1141 	ret = fchdir(newfd);
1142 bail:
1143 	oerrno = errno;
1144 	if (fd < 0)
1145 		(void)_close(newfd);
1146 	errno = oerrno;
1147 	return (ret);
1148 }
1149 
1150 /*
1151  * Check if the filesystem for "ent" has UFS-style links.
1152  */
1153 static int
1154 fts_ufslinks(FTS *sp, const FTSENT *ent)
1155 {
1156 	struct _fts_private *priv;
1157 	const char **cpp;
1158 
1159 	priv = (struct _fts_private *)sp;
1160 	/*
1161 	 * If this node's device is different from the previous, grab
1162 	 * the filesystem information, and decide on the reliability
1163 	 * of the link information from this filesystem for stat(2)
1164 	 * avoidance.
1165 	 */
1166 	if (priv->ftsp_dev != ent->fts_dev) {
1167 		if (statfs(ent->fts_path, &priv->ftsp_statfs) != -1) {
1168 			priv->ftsp_dev = ent->fts_dev;
1169 			priv->ftsp_linksreliable = 0;
1170 			for (cpp = ufslike_filesystems; *cpp; cpp++) {
1171 				if (strcmp(priv->ftsp_statfs.f_fstypename,
1172 				    *cpp) == 0) {
1173 					priv->ftsp_linksreliable = 1;
1174 					break;
1175 				}
1176 			}
1177 		} else {
1178 			priv->ftsp_linksreliable = 0;
1179 		}
1180 	}
1181 	return (priv->ftsp_linksreliable);
1182 }
1183