xref: /freebsd/lib/libc/gen/fts.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
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 static FTSENT	*fts_alloc(FTS *, char *, int);
56 static FTSENT	*fts_build(FTS *, int);
57 static void	 fts_lfree(FTSENT *);
58 static void	 fts_load(FTS *, FTSENT *);
59 static size_t	 fts_maxarglen(char * const *);
60 static void	 fts_padjust(FTS *, FTSENT *);
61 static int	 fts_palloc(FTS *, size_t);
62 static FTSENT	*fts_sort(FTS *, FTSENT *, int);
63 static u_short	 fts_stat(FTS *, FTSENT *, int);
64 static int	 fts_safe_changedir(FTS *, FTSENT *, int, char *);
65 static int	 fts_ufslinks(FTS *, const FTSENT *);
66 
67 #define	ISDOT(a)	(a[0] == '.' && (!a[1] || (a[1] == '.' && !a[2])))
68 
69 #define	CLR(opt)	(sp->fts_options &= ~(opt))
70 #define	ISSET(opt)	(sp->fts_options & (opt))
71 #define	SET(opt)	(sp->fts_options |= (opt))
72 
73 #define	FCHDIR(sp, fd)	(!ISSET(FTS_NOCHDIR) && fchdir(fd))
74 
75 /* fts_build flags */
76 #define	BCHILD		1		/* fts_children */
77 #define	BNAMES		2		/* fts_children, names only */
78 #define	BREAD		3		/* fts_read */
79 
80 /*
81  * Internal representation of an FTS, including extra implementation
82  * details.  The FTS returned from fts_open points to this structure's
83  * ftsp_fts member (and can be cast to an _fts_private as required)
84  */
85 struct _fts_private {
86 	FTS		ftsp_fts;
87 	struct statfs	ftsp_statfs;
88 	dev_t		ftsp_dev;
89 	int		ftsp_linksreliable;
90 };
91 
92 /*
93  * The "FTS_NOSTAT" option can avoid a lot of calls to stat(2) if it
94  * knows that a directory could not possibly have subdirectories.  This
95  * is decided by looking at the link count: a subdirectory would
96  * increment its parent's link count by virtue of its own ".." entry.
97  * This assumption only holds for UFS-like filesystems that implement
98  * links and directories this way, so we must punt for others.
99  */
100 
101 static const char *ufslike_filesystems[] = {
102 	"ufs",
103 	"nfs",
104 	"nfs4",
105 	"ext2fs",
106 	0
107 };
108 
109 FTS *
110 fts_open(argv, options, compar)
111 	char * const *argv;
112 	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 	int nitems;
119 	FTSENT *parent, *tmp;
120 	int len;
121 
122 	/* Options check. */
123 	if (options & ~FTS_OPTIONMASK) {
124 		errno = EINVAL;
125 		return (NULL);
126 	}
127 
128 	/* Allocate/initialize the stream. */
129 	if ((priv = malloc(sizeof(*priv))) == NULL)
130 		return (NULL);
131 	memset(priv, 0, sizeof(*priv));
132 	sp = &priv->ftsp_fts;
133 	sp->fts_compar = compar;
134 	sp->fts_options = options;
135 
136 	/* Shush, GCC. */
137 	tmp = NULL;
138 
139 	/* Logical walks turn on NOCHDIR; symbolic links are too hard. */
140 	if (ISSET(FTS_LOGICAL))
141 		SET(FTS_NOCHDIR);
142 
143 	/*
144 	 * Start out with 1K of path space, and enough, in any case,
145 	 * to hold the user's paths.
146 	 */
147 	if (fts_palloc(sp, MAX(fts_maxarglen(argv), MAXPATHLEN)))
148 		goto mem1;
149 
150 	/* Allocate/initialize root's parent. */
151 	if ((parent = fts_alloc(sp, "", 0)) == NULL)
152 		goto mem2;
153 	parent->fts_level = FTS_ROOTPARENTLEVEL;
154 
155 	/* Allocate/initialize root(s). */
156 	for (root = NULL, nitems = 0; *argv != NULL; ++argv, ++nitems) {
157 		/* Don't allow zero-length paths. */
158 		if ((len = strlen(*argv)) == 0) {
159 			errno = ENOENT;
160 			goto mem3;
161 		}
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));
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) && (sp->fts_rfd = _open(".", O_RDONLY, 0)) < 0)
211 		SET(FTS_NOCHDIR);
212 
213 	return (sp);
214 
215 mem3:	fts_lfree(root);
216 	free(parent);
217 mem2:	free(sp->fts_path);
218 mem1:	free(sp);
219 	return (NULL);
220 }
221 
222 static void
223 fts_load(sp, p)
224 	FTS *sp;
225 	FTSENT *p;
226 {
227 	int len;
228 	char *cp;
229 
230 	/*
231 	 * Load the stream structure for the next traversal.  Since we don't
232 	 * actually enter the directory until after the preorder visit, set
233 	 * the fts_accpath field specially so the chdir gets done to the right
234 	 * place and the user can access the first node.  From fts_open it's
235 	 * known that the path will fit.
236 	 */
237 	len = p->fts_pathlen = p->fts_namelen;
238 	memmove(sp->fts_path, p->fts_name, len + 1);
239 	if ((cp = strrchr(p->fts_name, '/')) && (cp != p->fts_name || cp[1])) {
240 		len = strlen(++cp);
241 		memmove(p->fts_name, cp, len + 1);
242 		p->fts_namelen = len;
243 	}
244 	p->fts_accpath = p->fts_path = sp->fts_path;
245 	sp->fts_dev = p->fts_dev;
246 }
247 
248 int
249 fts_close(sp)
250 	FTS *sp;
251 {
252 	FTSENT *freep, *p;
253 	int saved_errno;
254 
255 	/*
256 	 * This still works if we haven't read anything -- the dummy structure
257 	 * points to the root list, so we step through to the end of the root
258 	 * list which has a valid parent pointer.
259 	 */
260 	if (sp->fts_cur) {
261 		for (p = sp->fts_cur; p->fts_level >= FTS_ROOTLEVEL;) {
262 			freep = p;
263 			p = p->fts_link != NULL ? p->fts_link : p->fts_parent;
264 			free(freep);
265 		}
266 		free(p);
267 	}
268 
269 	/* Free up child linked list, sort array, path buffer. */
270 	if (sp->fts_child)
271 		fts_lfree(sp->fts_child);
272 	if (sp->fts_array)
273 		free(sp->fts_array);
274 	free(sp->fts_path);
275 
276 	/* Return to original directory, save errno if necessary. */
277 	if (!ISSET(FTS_NOCHDIR)) {
278 		saved_errno = fchdir(sp->fts_rfd) ? errno : 0;
279 		(void)_close(sp->fts_rfd);
280 
281 		/* Set errno and return. */
282 		if (saved_errno != 0) {
283 			/* Free up the stream pointer. */
284 			free(sp);
285 			errno = saved_errno;
286 			return (-1);
287 		}
288 	}
289 
290 	/* Free up the stream pointer. */
291 	free(sp);
292 	return (0);
293 }
294 
295 /*
296  * Special case of "/" at the end of the path so that slashes aren't
297  * appended which would cause paths to be written as "....//foo".
298  */
299 #define	NAPPEND(p)							\
300 	(p->fts_path[p->fts_pathlen - 1] == '/'				\
301 	    ? p->fts_pathlen - 1 : p->fts_pathlen)
302 
303 FTSENT *
304 fts_read(sp)
305 	FTS *sp;
306 {
307 	FTSENT *p, *tmp;
308 	int instr;
309 	char *t;
310 	int saved_errno;
311 
312 	/* If finished or unrecoverable error, return NULL. */
313 	if (sp->fts_cur == NULL || ISSET(FTS_STOP))
314 		return (NULL);
315 
316 	/* Set current node pointer. */
317 	p = sp->fts_cur;
318 
319 	/* Save and zero out user instructions. */
320 	instr = p->fts_instr;
321 	p->fts_instr = FTS_NOINSTR;
322 
323 	/* Any type of file may be re-visited; re-stat and re-turn. */
324 	if (instr == FTS_AGAIN) {
325 		p->fts_info = fts_stat(sp, p, 0);
326 		return (p);
327 	}
328 
329 	/*
330 	 * Following a symlink -- SLNONE test allows application to see
331 	 * SLNONE and recover.  If indirecting through a symlink, have
332 	 * keep a pointer to current location.  If unable to get that
333 	 * pointer, follow fails.
334 	 */
335 	if (instr == FTS_FOLLOW &&
336 	    (p->fts_info == FTS_SL || p->fts_info == FTS_SLNONE)) {
337 		p->fts_info = fts_stat(sp, p, 1);
338 		if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {
339 			if ((p->fts_symfd = _open(".", O_RDONLY, 0)) < 0) {
340 				p->fts_errno = errno;
341 				p->fts_info = FTS_ERR;
342 			} else
343 				p->fts_flags |= FTS_SYMFOLLOW;
344 		}
345 		return (p);
346 	}
347 
348 	/* Directory in pre-order. */
349 	if (p->fts_info == FTS_D) {
350 		/* If skipped or crossed mount point, do post-order visit. */
351 		if (instr == FTS_SKIP ||
352 		    (ISSET(FTS_XDEV) && p->fts_dev != sp->fts_dev)) {
353 			if (p->fts_flags & FTS_SYMFOLLOW)
354 				(void)_close(p->fts_symfd);
355 			if (sp->fts_child) {
356 				fts_lfree(sp->fts_child);
357 				sp->fts_child = NULL;
358 			}
359 			p->fts_info = FTS_DP;
360 			return (p);
361 		}
362 
363 		/* Rebuild if only read the names and now traversing. */
364 		if (sp->fts_child != NULL && ISSET(FTS_NAMEONLY)) {
365 			CLR(FTS_NAMEONLY);
366 			fts_lfree(sp->fts_child);
367 			sp->fts_child = NULL;
368 		}
369 
370 		/*
371 		 * Cd to the subdirectory.
372 		 *
373 		 * If have already read and now fail to chdir, whack the list
374 		 * to make the names come out right, and set the parent errno
375 		 * so the application will eventually get an error condition.
376 		 * Set the FTS_DONTCHDIR flag so that when we logically change
377 		 * directories back to the parent we don't do a chdir.
378 		 *
379 		 * If haven't read do so.  If the read fails, fts_build sets
380 		 * FTS_STOP or the fts_info field of the node.
381 		 */
382 		if (sp->fts_child != NULL) {
383 			if (fts_safe_changedir(sp, p, -1, p->fts_accpath)) {
384 				p->fts_errno = errno;
385 				p->fts_flags |= FTS_DONTCHDIR;
386 				for (p = sp->fts_child; p != NULL;
387 				    p = p->fts_link)
388 					p->fts_accpath =
389 					    p->fts_parent->fts_accpath;
390 			}
391 		} else if ((sp->fts_child = fts_build(sp, BREAD)) == NULL) {
392 			if (ISSET(FTS_STOP))
393 				return (NULL);
394 			return (p);
395 		}
396 		p = sp->fts_child;
397 		sp->fts_child = NULL;
398 		goto name;
399 	}
400 
401 	/* Move to the next node on this level. */
402 next:	tmp = p;
403 	if ((p = p->fts_link) != NULL) {
404 		free(tmp);
405 
406 		/*
407 		 * If reached the top, return to the original directory (or
408 		 * the root of the tree), and load the paths for the next root.
409 		 */
410 		if (p->fts_level == FTS_ROOTLEVEL) {
411 			if (FCHDIR(sp, sp->fts_rfd)) {
412 				SET(FTS_STOP);
413 				return (NULL);
414 			}
415 			fts_load(sp, p);
416 			return (sp->fts_cur = p);
417 		}
418 
419 		/*
420 		 * User may have called fts_set on the node.  If skipped,
421 		 * ignore.  If followed, get a file descriptor so we can
422 		 * get back if necessary.
423 		 */
424 		if (p->fts_instr == FTS_SKIP)
425 			goto next;
426 		if (p->fts_instr == FTS_FOLLOW) {
427 			p->fts_info = fts_stat(sp, p, 1);
428 			if (p->fts_info == FTS_D && !ISSET(FTS_NOCHDIR)) {
429 				if ((p->fts_symfd =
430 				    _open(".", O_RDONLY, 0)) < 0) {
431 					p->fts_errno = errno;
432 					p->fts_info = FTS_ERR;
433 				} else
434 					p->fts_flags |= FTS_SYMFOLLOW;
435 			}
436 			p->fts_instr = FTS_NOINSTR;
437 		}
438 
439 name:		t = sp->fts_path + NAPPEND(p->fts_parent);
440 		*t++ = '/';
441 		memmove(t, p->fts_name, p->fts_namelen + 1);
442 		return (sp->fts_cur = p);
443 	}
444 
445 	/* Move up to the parent node. */
446 	p = tmp->fts_parent;
447 	free(tmp);
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(p);
455 		errno = 0;
456 		return (sp->fts_cur = NULL);
457 	}
458 
459 	/* NUL terminate the pathname. */
460 	sp->fts_path[p->fts_pathlen] = '\0';
461 
462 	/*
463 	 * Return to the parent directory.  If at a root node or came through
464 	 * a symlink, go back through the file descriptor.  Otherwise, cd up
465 	 * one directory.
466 	 */
467 	if (p->fts_level == FTS_ROOTLEVEL) {
468 		if (FCHDIR(sp, sp->fts_rfd)) {
469 			SET(FTS_STOP);
470 			return (NULL);
471 		}
472 	} else if (p->fts_flags & FTS_SYMFOLLOW) {
473 		if (FCHDIR(sp, p->fts_symfd)) {
474 			saved_errno = errno;
475 			(void)_close(p->fts_symfd);
476 			errno = saved_errno;
477 			SET(FTS_STOP);
478 			return (NULL);
479 		}
480 		(void)_close(p->fts_symfd);
481 	} else if (!(p->fts_flags & FTS_DONTCHDIR) &&
482 	    fts_safe_changedir(sp, p->fts_parent, -1, "..")) {
483 		SET(FTS_STOP);
484 		return (NULL);
485 	}
486 	p->fts_info = p->fts_errno ? FTS_ERR : FTS_DP;
487 	return (sp->fts_cur = p);
488 }
489 
490 /*
491  * Fts_set takes the stream as an argument although it's not used in this
492  * implementation; it would be necessary if anyone wanted to add global
493  * semantics to fts using fts_set.  An error return is allowed for similar
494  * reasons.
495  */
496 /* ARGSUSED */
497 int
498 fts_set(sp, p, instr)
499 	FTS *sp;
500 	FTSENT *p;
501 	int instr;
502 {
503 	if (instr != 0 && instr != FTS_AGAIN && instr != FTS_FOLLOW &&
504 	    instr != FTS_NOINSTR && instr != FTS_SKIP) {
505 		errno = EINVAL;
506 		return (1);
507 	}
508 	p->fts_instr = instr;
509 	return (0);
510 }
511 
512 FTSENT *
513 fts_children(sp, instr)
514 	FTS *sp;
515 	int instr;
516 {
517 	FTSENT *p;
518 	int fd;
519 
520 	if (instr != 0 && instr != FTS_NAMEONLY) {
521 		errno = EINVAL;
522 		return (NULL);
523 	}
524 
525 	/* Set current node pointer. */
526 	p = sp->fts_cur;
527 
528 	/*
529 	 * Errno set to 0 so user can distinguish empty directory from
530 	 * an error.
531 	 */
532 	errno = 0;
533 
534 	/* Fatal errors stop here. */
535 	if (ISSET(FTS_STOP))
536 		return (NULL);
537 
538 	/* Return logical hierarchy of user's arguments. */
539 	if (p->fts_info == FTS_INIT)
540 		return (p->fts_link);
541 
542 	/*
543 	 * If not a directory being visited in pre-order, stop here.  Could
544 	 * allow FTS_DNR, assuming the user has fixed the problem, but the
545 	 * same effect is available with FTS_AGAIN.
546 	 */
547 	if (p->fts_info != FTS_D /* && p->fts_info != FTS_DNR */)
548 		return (NULL);
549 
550 	/* Free up any previous child list. */
551 	if (sp->fts_child != NULL)
552 		fts_lfree(sp->fts_child);
553 
554 	if (instr == FTS_NAMEONLY) {
555 		SET(FTS_NAMEONLY);
556 		instr = BNAMES;
557 	} else
558 		instr = BCHILD;
559 
560 	/*
561 	 * If using chdir on a relative path and called BEFORE fts_read does
562 	 * its chdir to the root of a traversal, we can lose -- we need to
563 	 * chdir into the subdirectory, and we don't know where the current
564 	 * directory is, so we can't get back so that the upcoming chdir by
565 	 * fts_read will work.
566 	 */
567 	if (p->fts_level != FTS_ROOTLEVEL || p->fts_accpath[0] == '/' ||
568 	    ISSET(FTS_NOCHDIR))
569 		return (sp->fts_child = fts_build(sp, instr));
570 
571 	if ((fd = _open(".", O_RDONLY, 0)) < 0)
572 		return (NULL);
573 	sp->fts_child = fts_build(sp, instr);
574 	if (fchdir(fd))
575 		return (NULL);
576 	(void)_close(fd);
577 	return (sp->fts_child);
578 }
579 
580 #ifndef fts_get_clientptr
581 #error "fts_get_clientptr not defined"
582 #endif
583 
584 void *
585 (fts_get_clientptr)(FTS *sp)
586 {
587 
588 	return (fts_get_clientptr(sp));
589 }
590 
591 #ifndef fts_get_stream
592 #error "fts_get_stream not defined"
593 #endif
594 
595 FTS *
596 (fts_get_stream)(FTSENT *p)
597 {
598 	return (fts_get_stream(p));
599 }
600 
601 void
602 fts_set_clientptr(FTS *sp, void *clientptr)
603 {
604 
605 	sp->fts_clientptr = clientptr;
606 }
607 
608 /*
609  * This is the tricky part -- do not casually change *anything* in here.  The
610  * idea is to build the linked list of entries that are used by fts_children
611  * and fts_read.  There are lots of special cases.
612  *
613  * The real slowdown in walking the tree is the stat calls.  If FTS_NOSTAT is
614  * set and it's a physical walk (so that symbolic links can't be directories),
615  * we can do things quickly.  First, if it's a 4.4BSD file system, the type
616  * of the file is in the directory entry.  Otherwise, we assume that the number
617  * of subdirectories in a node is equal to the number of links to the parent.
618  * The former skips all stat calls.  The latter skips stat calls in any leaf
619  * directories and for any files after the subdirectories in the directory have
620  * been found, cutting the stat calls by about 2/3.
621  */
622 static FTSENT *
623 fts_build(sp, type)
624 	FTS *sp;
625 	int type;
626 {
627 	struct dirent *dp;
628 	FTSENT *p, *head;
629 	int nitems;
630 	FTSENT *cur, *tail;
631 	DIR *dirp;
632 	void *oldaddr;
633 	size_t dnamlen;
634 	int cderrno, descend, len, level, maxlen, nlinks, oflag, saved_errno,
635 	    nostat, doadjust;
636 	char *cp;
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, (int)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 		if (len + dnamlen >= USHRT_MAX) {
774 			/*
775 			 * In an FTSENT, fts_pathlen is a u_short so it is
776 			 * possible to wraparound here.  If we do, free up
777 			 * the current structure and the structures already
778 			 * allocated, then error out with ENAMETOOLONG.
779 			 */
780 			free(p);
781 			fts_lfree(head);
782 			(void)closedir(dirp);
783 			cur->fts_info = FTS_ERR;
784 			SET(FTS_STOP);
785 			errno = ENAMETOOLONG;
786 			return (NULL);
787 		}
788 		p->fts_level = level;
789 		p->fts_parent = sp->fts_cur;
790 		p->fts_pathlen = len + dnamlen;
791 
792 #ifdef FTS_WHITEOUT
793 		if (dp->d_type == DT_WHT)
794 			p->fts_flags |= FTS_ISW;
795 #endif
796 
797 		if (cderrno) {
798 			if (nlinks) {
799 				p->fts_info = FTS_NS;
800 				p->fts_errno = cderrno;
801 			} else
802 				p->fts_info = FTS_NSOK;
803 			p->fts_accpath = cur->fts_accpath;
804 		} else if (nlinks == 0
805 #ifdef DT_DIR
806 		    || (nostat &&
807 		    dp->d_type != DT_DIR && dp->d_type != DT_UNKNOWN)
808 #endif
809 		    ) {
810 			p->fts_accpath =
811 			    ISSET(FTS_NOCHDIR) ? p->fts_path : p->fts_name;
812 			p->fts_info = FTS_NSOK;
813 		} else {
814 			/* Build a file name for fts_stat to stat. */
815 			if (ISSET(FTS_NOCHDIR)) {
816 				p->fts_accpath = p->fts_path;
817 				memmove(cp, p->fts_name, p->fts_namelen + 1);
818 			} else
819 				p->fts_accpath = p->fts_name;
820 			/* Stat it. */
821 			p->fts_info = fts_stat(sp, p, 0);
822 
823 			/* Decrement link count if applicable. */
824 			if (nlinks > 0 && (p->fts_info == FTS_D ||
825 			    p->fts_info == FTS_DC || p->fts_info == FTS_DOT))
826 				--nlinks;
827 		}
828 
829 		/* We walk in directory order so "ls -f" doesn't get upset. */
830 		p->fts_link = NULL;
831 		if (head == NULL)
832 			head = tail = p;
833 		else {
834 			tail->fts_link = p;
835 			tail = p;
836 		}
837 		++nitems;
838 	}
839 	if (dirp)
840 		(void)closedir(dirp);
841 
842 	/*
843 	 * If realloc() changed the address of the path, adjust the
844 	 * addresses for the rest of the tree and the dir list.
845 	 */
846 	if (doadjust)
847 		fts_padjust(sp, head);
848 
849 	/*
850 	 * If not changing directories, reset the path back to original
851 	 * state.
852 	 */
853 	if (ISSET(FTS_NOCHDIR)) {
854 		if (len == sp->fts_pathlen || nitems == 0)
855 			--cp;
856 		*cp = '\0';
857 	}
858 
859 	/*
860 	 * If descended after called from fts_children or after called from
861 	 * fts_read and nothing found, get back.  At the root level we use
862 	 * the saved fd; if one of fts_open()'s arguments is a relative path
863 	 * to an empty directory, we wind up here with no other way back.  If
864 	 * can't get back, we're done.
865 	 */
866 	if (descend && (type == BCHILD || !nitems) &&
867 	    (cur->fts_level == FTS_ROOTLEVEL ?
868 	    FCHDIR(sp, sp->fts_rfd) :
869 	    fts_safe_changedir(sp, cur->fts_parent, -1, ".."))) {
870 		cur->fts_info = FTS_ERR;
871 		SET(FTS_STOP);
872 		return (NULL);
873 	}
874 
875 	/* If didn't find anything, return NULL. */
876 	if (!nitems) {
877 		if (type == BREAD)
878 			cur->fts_info = FTS_DP;
879 		return (NULL);
880 	}
881 
882 	/* Sort the entries. */
883 	if (sp->fts_compar && nitems > 1)
884 		head = fts_sort(sp, head, nitems);
885 	return (head);
886 }
887 
888 static u_short
889 fts_stat(sp, p, follow)
890 	FTS *sp;
891 	FTSENT *p;
892 	int follow;
893 {
894 	FTSENT *t;
895 	dev_t dev;
896 	ino_t ino;
897 	struct stat *sbp, sb;
898 	int saved_errno;
899 
900 	/* If user needs stat info, stat buffer already allocated. */
901 	sbp = ISSET(FTS_NOSTAT) ? &sb : p->fts_statp;
902 
903 #ifdef FTS_WHITEOUT
904 	/* Check for whiteout. */
905 	if (p->fts_flags & FTS_ISW) {
906 		if (sbp != &sb) {
907 			memset(sbp, '\0', sizeof(*sbp));
908 			sbp->st_mode = S_IFWHT;
909 		}
910 		return (FTS_W);
911 	}
912 #endif
913 
914 	/*
915 	 * If doing a logical walk, or application requested FTS_FOLLOW, do
916 	 * a stat(2).  If that fails, check for a non-existent symlink.  If
917 	 * fail, set the errno from the stat call.
918 	 */
919 	if (ISSET(FTS_LOGICAL) || follow) {
920 		if (stat(p->fts_accpath, sbp)) {
921 			saved_errno = errno;
922 			if (!lstat(p->fts_accpath, sbp)) {
923 				errno = 0;
924 				return (FTS_SLNONE);
925 			}
926 			p->fts_errno = saved_errno;
927 			goto err;
928 		}
929 	} else if (lstat(p->fts_accpath, sbp)) {
930 		p->fts_errno = errno;
931 err:		memset(sbp, 0, sizeof(struct stat));
932 		return (FTS_NS);
933 	}
934 
935 	if (S_ISDIR(sbp->st_mode)) {
936 		/*
937 		 * Set the device/inode.  Used to find cycles and check for
938 		 * crossing mount points.  Also remember the link count, used
939 		 * in fts_build to limit the number of stat calls.  It is
940 		 * understood that these fields are only referenced if fts_info
941 		 * is set to FTS_D.
942 		 */
943 		dev = p->fts_dev = sbp->st_dev;
944 		ino = p->fts_ino = sbp->st_ino;
945 		p->fts_nlink = sbp->st_nlink;
946 
947 		if (ISDOT(p->fts_name))
948 			return (FTS_DOT);
949 
950 		/*
951 		 * Cycle detection is done by brute force when the directory
952 		 * is first encountered.  If the tree gets deep enough or the
953 		 * number of symbolic links to directories is high enough,
954 		 * something faster might be worthwhile.
955 		 */
956 		for (t = p->fts_parent;
957 		    t->fts_level >= FTS_ROOTLEVEL; t = t->fts_parent)
958 			if (ino == t->fts_ino && dev == t->fts_dev) {
959 				p->fts_cycle = t;
960 				return (FTS_DC);
961 			}
962 		return (FTS_D);
963 	}
964 	if (S_ISLNK(sbp->st_mode))
965 		return (FTS_SL);
966 	if (S_ISREG(sbp->st_mode))
967 		return (FTS_F);
968 	return (FTS_DEFAULT);
969 }
970 
971 /*
972  * The comparison function takes pointers to pointers to FTSENT structures.
973  * Qsort wants a comparison function that takes pointers to void.
974  * (Both with appropriate levels of const-poisoning, of course!)
975  * Use a trampoline function to deal with the difference.
976  */
977 static int
978 fts_compar(const void *a, const void *b)
979 {
980 	FTS *parent;
981 
982 	parent = (*(const FTSENT * const *)a)->fts_fts;
983 	return (*parent->fts_compar)(a, b);
984 }
985 
986 static FTSENT *
987 fts_sort(sp, head, nitems)
988 	FTS *sp;
989 	FTSENT *head;
990 	int nitems;
991 {
992 	FTSENT **ap, *p;
993 
994 	/*
995 	 * Construct an array of pointers to the structures and call qsort(3).
996 	 * Reassemble the array in the order returned by qsort.  If unable to
997 	 * sort for memory reasons, return the directory entries in their
998 	 * current order.  Allocate enough space for the current needs plus
999 	 * 40 so don't realloc one entry at a time.
1000 	 */
1001 	if (nitems > sp->fts_nitems) {
1002 		sp->fts_nitems = nitems + 40;
1003 		if ((sp->fts_array = reallocf(sp->fts_array,
1004 		    sp->fts_nitems * sizeof(FTSENT *))) == NULL) {
1005 			sp->fts_nitems = 0;
1006 			return (head);
1007 		}
1008 	}
1009 	for (ap = sp->fts_array, p = head; p; p = p->fts_link)
1010 		*ap++ = p;
1011 	qsort(sp->fts_array, nitems, sizeof(FTSENT *), fts_compar);
1012 	for (head = *(ap = sp->fts_array); --nitems; ++ap)
1013 		ap[0]->fts_link = ap[1];
1014 	ap[0]->fts_link = NULL;
1015 	return (head);
1016 }
1017 
1018 static FTSENT *
1019 fts_alloc(sp, name, namelen)
1020 	FTS *sp;
1021 	char *name;
1022 	int namelen;
1023 {
1024 	FTSENT *p;
1025 	size_t len;
1026 
1027 	struct ftsent_withstat {
1028 		FTSENT	ent;
1029 		struct	stat statbuf;
1030 	};
1031 
1032 	/*
1033 	 * The file name is a variable length array and no stat structure is
1034 	 * necessary if the user has set the nostat bit.  Allocate the FTSENT
1035 	 * structure, the file name and the stat structure in one chunk, but
1036 	 * be careful that the stat structure is reasonably aligned.
1037 	 */
1038 	if (ISSET(FTS_NOSTAT))
1039 		len = sizeof(FTSENT) + namelen + 1;
1040 	else
1041 		len = sizeof(struct ftsent_withstat) + namelen + 1;
1042 
1043 	if ((p = malloc(len)) == NULL)
1044 		return (NULL);
1045 
1046 	if (ISSET(FTS_NOSTAT)) {
1047 		p->fts_name = (char *)(p + 1);
1048 		p->fts_statp = NULL;
1049 	} else {
1050 		p->fts_name = (char *)((struct ftsent_withstat *)p + 1);
1051 		p->fts_statp = &((struct ftsent_withstat *)p)->statbuf;
1052 	}
1053 
1054 	/* Copy the name and guarantee NUL termination. */
1055 	memcpy(p->fts_name, name, namelen);
1056 	p->fts_name[namelen] = '\0';
1057 	p->fts_namelen = namelen;
1058 	p->fts_path = sp->fts_path;
1059 	p->fts_errno = 0;
1060 	p->fts_flags = 0;
1061 	p->fts_instr = FTS_NOINSTR;
1062 	p->fts_number = 0;
1063 	p->fts_pointer = NULL;
1064 	p->fts_fts = sp;
1065 	return (p);
1066 }
1067 
1068 static void
1069 fts_lfree(head)
1070 	FTSENT *head;
1071 {
1072 	FTSENT *p;
1073 
1074 	/* Free a linked list of structures. */
1075 	while ((p = head)) {
1076 		head = head->fts_link;
1077 		free(p);
1078 	}
1079 }
1080 
1081 /*
1082  * Allow essentially unlimited paths; find, rm, ls should all work on any tree.
1083  * Most systems will allow creation of paths much longer than MAXPATHLEN, even
1084  * though the kernel won't resolve them.  Add the size (not just what's needed)
1085  * plus 256 bytes so don't realloc the path 2 bytes at a time.
1086  */
1087 static int
1088 fts_palloc(sp, more)
1089 	FTS *sp;
1090 	size_t more;
1091 {
1092 
1093 	sp->fts_pathlen += more + 256;
1094 	/*
1095 	 * Check for possible wraparound.  In an FTS, fts_pathlen is
1096 	 * a signed int but in an FTSENT it is an unsigned short.
1097 	 * We limit fts_pathlen to USHRT_MAX to be safe in both cases.
1098 	 */
1099 	if (sp->fts_pathlen < 0 || sp->fts_pathlen >= USHRT_MAX) {
1100 		if (sp->fts_path)
1101 			free(sp->fts_path);
1102 		sp->fts_path = NULL;
1103 		errno = ENAMETOOLONG;
1104 		return (1);
1105 	}
1106 	sp->fts_path = reallocf(sp->fts_path, sp->fts_pathlen);
1107 	return (sp->fts_path == NULL);
1108 }
1109 
1110 /*
1111  * When the path is realloc'd, have to fix all of the pointers in structures
1112  * already returned.
1113  */
1114 static void
1115 fts_padjust(sp, head)
1116 	FTS *sp;
1117 	FTSENT *head;
1118 {
1119 	FTSENT *p;
1120 	char *addr = sp->fts_path;
1121 
1122 #define	ADJUST(p) do {							\
1123 	if ((p)->fts_accpath != (p)->fts_name) {			\
1124 		(p)->fts_accpath =					\
1125 		    (char *)addr + ((p)->fts_accpath - (p)->fts_path);	\
1126 	}								\
1127 	(p)->fts_path = addr;						\
1128 } while (0)
1129 	/* Adjust the current set of children. */
1130 	for (p = sp->fts_child; p; p = p->fts_link)
1131 		ADJUST(p);
1132 
1133 	/* Adjust the rest of the tree, including the current level. */
1134 	for (p = head; p->fts_level >= FTS_ROOTLEVEL;) {
1135 		ADJUST(p);
1136 		p = p->fts_link ? p->fts_link : p->fts_parent;
1137 	}
1138 }
1139 
1140 static size_t
1141 fts_maxarglen(argv)
1142 	char * const *argv;
1143 {
1144 	size_t len, max;
1145 
1146 	for (max = 0; *argv; ++argv)
1147 		if ((len = strlen(*argv)) > max)
1148 			max = len;
1149 	return (max + 1);
1150 }
1151 
1152 /*
1153  * Change to dir specified by fd or p->fts_accpath without getting
1154  * tricked by someone changing the world out from underneath us.
1155  * Assumes p->fts_dev and p->fts_ino are filled in.
1156  */
1157 static int
1158 fts_safe_changedir(sp, p, fd, path)
1159 	FTS *sp;
1160 	FTSENT *p;
1161 	int fd;
1162 	char *path;
1163 {
1164 	int ret, oerrno, newfd;
1165 	struct stat sb;
1166 
1167 	newfd = fd;
1168 	if (ISSET(FTS_NOCHDIR))
1169 		return (0);
1170 	if (fd < 0 && (newfd = _open(path, O_RDONLY, 0)) < 0)
1171 		return (-1);
1172 	if (_fstat(newfd, &sb)) {
1173 		ret = -1;
1174 		goto bail;
1175 	}
1176 	if (p->fts_dev != sb.st_dev || p->fts_ino != sb.st_ino) {
1177 		errno = ENOENT;		/* disinformation */
1178 		ret = -1;
1179 		goto bail;
1180 	}
1181 	ret = fchdir(newfd);
1182 bail:
1183 	oerrno = errno;
1184 	if (fd < 0)
1185 		(void)_close(newfd);
1186 	errno = oerrno;
1187 	return (ret);
1188 }
1189 
1190 /*
1191  * Check if the filesystem for "ent" has UFS-style links.
1192  */
1193 static int
1194 fts_ufslinks(FTS *sp, const FTSENT *ent)
1195 {
1196 	struct _fts_private *priv;
1197 	const char **cpp;
1198 
1199 	priv = (struct _fts_private *)sp;
1200 	/*
1201 	 * If this node's device is different from the previous, grab
1202 	 * the filesystem information, and decide on the reliability
1203 	 * of the link information from this filesystem for stat(2)
1204 	 * avoidance.
1205 	 */
1206 	if (priv->ftsp_dev != ent->fts_dev) {
1207 		if (statfs(ent->fts_path, &priv->ftsp_statfs) != -1) {
1208 			priv->ftsp_dev = ent->fts_dev;
1209 			priv->ftsp_linksreliable = 0;
1210 			for (cpp = ufslike_filesystems; *cpp; cpp++) {
1211 				if (strcmp(priv->ftsp_statfs.f_fstypename,
1212 				    *cpp) == 0) {
1213 					priv->ftsp_linksreliable = 1;
1214 					break;
1215 				}
1216 			}
1217 		} else {
1218 			priv->ftsp_linksreliable = 0;
1219 		}
1220 	}
1221 	return (priv->ftsp_linksreliable);
1222 }
1223