xref: /freebsd/usr.sbin/makefs/mtree.c (revision d06955f9bdb1416d9196043ed781f9b36dae9adc)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2011 Marcel Moolenaar
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26  */
27 
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30 
31 #include <sys/param.h>
32 #include <sys/queue.h>
33 #include <sys/sbuf.h>
34 #include <sys/stat.h>
35 #include <sys/types.h>
36 #include <assert.h>
37 #include <errno.h>
38 #include <fcntl.h>
39 #include <grp.h>
40 #include <inttypes.h>
41 #include <pwd.h>
42 #include <stdarg.h>
43 #include <stdbool.h>
44 #include <stddef.h>
45 #include <stdio.h>
46 #include <stdlib.h>
47 #include <string.h>
48 #include <strings.h>
49 #include <time.h>
50 #include <unistd.h>
51 #include <util.h>
52 #include <vis.h>
53 
54 #include "makefs.h"
55 
56 #ifndef ENOATTR
57 #define	ENOATTR	ENOMSG
58 #endif
59 
60 #define	IS_DOT(nm)	((nm)[0] == '.' && (nm)[1] == '\0')
61 #define	IS_DOTDOT(nm)	((nm)[0] == '.' && (nm)[1] == '.' && (nm)[2] == '\0')
62 
63 struct mtree_fileinfo {
64 	SLIST_ENTRY(mtree_fileinfo) next;
65 	FILE *fp;
66 	const char *name;
67 	u_int line;
68 };
69 
70 /* Global state used while parsing. */
71 static SLIST_HEAD(, mtree_fileinfo) mtree_fileinfo =
72     SLIST_HEAD_INITIALIZER(mtree_fileinfo);
73 static fsnode *mtree_root;
74 static fsnode *mtree_current;
75 static fsnode mtree_global;
76 static fsinode mtree_global_inode;
77 static u_int errors, warnings;
78 
79 static void mtree_error(const char *, ...) __printflike(1, 2);
80 static void mtree_warning(const char *, ...) __printflike(1, 2);
81 
82 static int
83 mtree_file_push(const char *name, FILE *fp)
84 {
85 	struct mtree_fileinfo *fi;
86 
87 	fi = emalloc(sizeof(*fi));
88 	if (strcmp(name, "-") == 0)
89 		fi->name = estrdup("(stdin)");
90 	else
91 		fi->name = estrdup(name);
92 	if (fi->name == NULL) {
93 		free(fi);
94 		return (ENOMEM);
95 	}
96 
97 	fi->fp = fp;
98 	fi->line = 0;
99 
100 	SLIST_INSERT_HEAD(&mtree_fileinfo, fi, next);
101 	return (0);
102 }
103 
104 static void
105 mtree_print(const char *msgtype, const char *fmt, va_list ap)
106 {
107 	struct mtree_fileinfo *fi;
108 
109 	if (msgtype != NULL) {
110 		fi = SLIST_FIRST(&mtree_fileinfo);
111 		if (fi != NULL)
112 			fprintf(stderr, "%s:%u: ", fi->name, fi->line);
113 		fprintf(stderr, "%s: ", msgtype);
114 	}
115 	vfprintf(stderr, fmt, ap);
116 }
117 
118 static void
119 mtree_error(const char *fmt, ...)
120 {
121 	va_list ap;
122 
123 	va_start(ap, fmt);
124 	mtree_print("error", fmt, ap);
125 	va_end(ap);
126 
127 	errors++;
128 	fputc('\n', stderr);
129 }
130 
131 static void
132 mtree_warning(const char *fmt, ...)
133 {
134 	va_list ap;
135 
136 	va_start(ap, fmt);
137 	mtree_print("warning", fmt, ap);
138 	va_end(ap);
139 
140 	warnings++;
141 	fputc('\n', stderr);
142 }
143 
144 #ifndef MAKEFS_MAX_TREE_DEPTH
145 # define MAKEFS_MAX_TREE_DEPTH (MAXPATHLEN/2)
146 #endif
147 
148 /* construct path to node->name */
149 static char *
150 mtree_file_path(fsnode *node)
151 {
152 	fsnode *pnode;
153 	struct sbuf *sb;
154 	char *res, *rp[MAKEFS_MAX_TREE_DEPTH];
155 	int depth;
156 
157 	depth = 0;
158 	rp[depth] = node->name;
159 	for (pnode = node->parent; pnode && depth < MAKEFS_MAX_TREE_DEPTH - 1;
160 	     pnode = pnode->parent) {
161 		if (strcmp(pnode->name, ".") == 0)
162 			break;
163 		rp[++depth] = pnode->name;
164 	}
165 
166 	sb = sbuf_new_auto();
167 	if (sb == NULL) {
168 		errno = ENOMEM;
169 		return (NULL);
170 	}
171 	while (depth > 0) {
172 		sbuf_cat(sb, rp[depth--]);
173 		sbuf_putc(sb, '/');
174 	}
175 	sbuf_cat(sb, rp[depth]);
176 	sbuf_finish(sb);
177 	res = estrdup(sbuf_data(sb));
178 	sbuf_delete(sb);
179 	if (res == NULL)
180 		errno = ENOMEM;
181 	return res;
182 
183 }
184 
185 /* mtree_resolve() sets errno to indicate why NULL was returned. */
186 static char *
187 mtree_resolve(const char *spec, int *istemp)
188 {
189 	struct sbuf *sb;
190 	char *res, *var = NULL;
191 	const char *base, *p, *v;
192 	size_t len;
193 	int c, error, quoted, subst;
194 
195 	len = strlen(spec);
196 	if (len == 0) {
197 		errno = EINVAL;
198 		return (NULL);
199 	}
200 
201 	c = (len > 1) ? (spec[0] == spec[len - 1]) ? spec[0] : 0 : 0;
202 	*istemp = (c == '`') ? 1 : 0;
203 	subst = (c == '`' || c == '"') ? 1 : 0;
204 	quoted = (subst || c == '\'') ? 1 : 0;
205 
206 	if (!subst) {
207 		res = estrdup(spec + quoted);
208 		if (quoted)
209 			res[len - 2] = '\0';
210 		return (res);
211 	}
212 
213 	sb = sbuf_new_auto();
214 	if (sb == NULL) {
215 		errno = ENOMEM;
216 		return (NULL);
217 	}
218 
219 	base = spec + 1;
220 	len -= 2;
221 	error = 0;
222 	while (len > 0) {
223 		p = strchr(base, '$');
224 		if (p == NULL) {
225 			sbuf_bcat(sb, base, len);
226 			base += len;
227 			len = 0;
228 			continue;
229 		}
230 		/* The following is safe. spec always starts with a quote. */
231 		if (p[-1] == '\\')
232 			p--;
233 		if (base != p) {
234 			sbuf_bcat(sb, base, p - base);
235 			len -= p - base;
236 			base = p;
237 		}
238 		if (*p == '\\') {
239 			sbuf_putc(sb, '$');
240 			base += 2;
241 			len -= 2;
242 			continue;
243 		}
244 		/* Skip the '$'. */
245 		base++;
246 		len--;
247 		/* Handle ${X} vs $X. */
248 		v = base;
249 		if (*base == '{') {
250 			p = strchr(v, '}');
251 			if (p == NULL)
252 				p = v;
253 		} else
254 			p = v;
255 		len -= (p + 1) - base;
256 		base = p + 1;
257 
258 		if (v == p) {
259 			sbuf_putc(sb, *v);
260 			continue;
261 		}
262 
263 		error = ENOMEM;
264 		var = ecalloc(p - v, 1);
265 		memcpy(var, v + 1, p - v - 1);
266 		if (strcmp(var, ".CURDIR") == 0) {
267 			res = getcwd(NULL, 0);
268 			if (res == NULL)
269 				break;
270 		} else if (strcmp(var, ".PROG") == 0) {
271 			res = estrdup(getprogname());
272 		} else {
273 			v = getenv(var);
274 			if (v != NULL) {
275 				res = estrdup(v);
276 			} else
277 				res = NULL;
278 		}
279 		error = 0;
280 
281 		if (res != NULL) {
282 			sbuf_cat(sb, res);
283 			free(res);
284 		}
285 		free(var);
286 		var = NULL;
287 	}
288 
289 	free(var);
290 	sbuf_finish(sb);
291 	res = (error == 0) ? strdup(sbuf_data(sb)) : NULL;
292 	sbuf_delete(sb);
293 	if (res == NULL)
294 		errno = ENOMEM;
295 	return (res);
296 }
297 
298 static int
299 skip_over(FILE *fp, const char *cs)
300 {
301 	int c;
302 
303 	c = getc(fp);
304 	while (c != EOF && strchr(cs, c) != NULL)
305 		c = getc(fp);
306 	if (c != EOF) {
307 		ungetc(c, fp);
308 		return (0);
309 	}
310 	return (ferror(fp) ? errno : -1);
311 }
312 
313 static int
314 skip_to(FILE *fp, const char *cs)
315 {
316 	int c;
317 
318 	c = getc(fp);
319 	while (c != EOF && strchr(cs, c) == NULL)
320 		c = getc(fp);
321 	if (c != EOF) {
322 		ungetc(c, fp);
323 		return (0);
324 	}
325 	return (ferror(fp) ? errno : -1);
326 }
327 
328 static int
329 read_word(FILE *fp, char *buf, size_t bufsz)
330 {
331 	struct mtree_fileinfo *fi;
332 	size_t idx, qidx;
333 	int c, done, error, esc, qlvl;
334 
335 	if (bufsz == 0)
336 		return (EINVAL);
337 
338 	done = 0;
339 	esc = 0;
340 	idx = 0;
341 	qidx = -1;
342 	qlvl = 0;
343 	do {
344 		c = getc(fp);
345 		switch (c) {
346 		case EOF:
347 			buf[idx] = '\0';
348 			error = ferror(fp) ? errno : -1;
349 			if (error == -1)
350 				mtree_error("unexpected end of file");
351 			return (error);
352 		case '#':		/* comment -- skip to end of line. */
353 			if (!esc) {
354 				error = skip_to(fp, "\n");
355 				if (!error)
356 					continue;
357 			}
358 			break;
359 		case '\\':
360 			esc++;
361 			break;
362 		case '`':
363 		case '\'':
364 		case '"':
365 			if (esc)
366 				break;
367 			if (qlvl == 0) {
368 				qlvl++;
369 				qidx = idx;
370 			} else if (c == buf[qidx]) {
371 				qlvl--;
372 				if (qlvl > 0) {
373 					do {
374 						qidx--;
375 					} while (buf[qidx] != '`' &&
376 					    buf[qidx] != '\'' &&
377 					    buf[qidx] != '"');
378 				} else
379 					qidx = -1;
380 			} else {
381 				qlvl++;
382 				qidx = idx;
383 			}
384 			break;
385 		case ' ':
386 		case '\t':
387 		case '\n':
388 			if (!esc && qlvl == 0) {
389 				ungetc(c, fp);
390 				c = '\0';
391 				done = 1;
392 				break;
393 			}
394 			if (c == '\n') {
395 				/*
396 				 * We going to eat the newline ourselves.
397 				 */
398 				if (qlvl > 0)
399 					mtree_warning("quoted word straddles "
400 					    "onto next line.");
401 				fi = SLIST_FIRST(&mtree_fileinfo);
402 				fi->line++;
403 			}
404 			break;
405 		default:
406 			if (esc)
407 				buf[idx++] = '\\';
408 			break;
409 		}
410 		buf[idx++] = c;
411 		esc = 0;
412 	} while (idx < bufsz && !done);
413 
414 	if (idx >= bufsz) {
415 		mtree_error("word too long to fit buffer (max %zu characters)",
416 		    bufsz);
417 		skip_to(fp, " \t\n");
418 	}
419 	return (0);
420 }
421 
422 static fsnode *
423 create_node(const char *name, u_int type, fsnode *parent, fsnode *global)
424 {
425 	fsnode *n;
426 
427 	n = ecalloc(1, sizeof(*n));
428 	n->name = estrdup(name);
429 	n->type = (type == 0) ? global->type : type;
430 	n->parent = parent;
431 
432 	n->inode = ecalloc(1, sizeof(*n->inode));
433 
434 	/* Assign global options/defaults. */
435 	memcpy(n->inode, global->inode, sizeof(*n->inode));
436 	n->inode->st.st_mode = (n->inode->st.st_mode & ~S_IFMT) | n->type;
437 
438 	if (n->type == S_IFLNK)
439 		n->symlink = global->symlink;
440 	else if (n->type == S_IFREG)
441 		n->contents = global->contents;
442 
443 	return (n);
444 }
445 
446 static void
447 destroy_node(fsnode *n)
448 {
449 
450 	assert(n != NULL);
451 	assert(n->name != NULL);
452 	assert(n->inode != NULL);
453 
454 	free(n->inode);
455 	free(n->name);
456 	free(n);
457 }
458 
459 static int
460 read_number(const char *tok, u_int base, intmax_t *res, intmax_t min,
461     intmax_t max)
462 {
463 	char *end;
464 	intmax_t val;
465 
466 	val = strtoimax(tok, &end, base);
467 	if (end == tok || end[0] != '\0')
468 		return (EINVAL);
469 	if (val < min || val > max)
470 		return (EDOM);
471 	*res = val;
472 	return (0);
473 }
474 
475 static int
476 read_mtree_keywords(FILE *fp, fsnode *node)
477 {
478 	char keyword[PATH_MAX];
479 	char *name, *p, *value;
480 	gid_t gid;
481 	uid_t uid;
482 	struct stat *st, sb;
483 	intmax_t num;
484 	u_long flset, flclr;
485 	int error, istemp;
486 	uint32_t type;
487 
488 	st = &node->inode->st;
489 	do {
490 		error = skip_over(fp, " \t");
491 		if (error)
492 			break;
493 
494 		error = read_word(fp, keyword, sizeof(keyword));
495 		if (error)
496 			break;
497 
498 		if (keyword[0] == '\0')
499 			break;
500 
501 		value = strchr(keyword, '=');
502 		if (value != NULL)
503 			*value++ = '\0';
504 
505 		/*
506 		 * We use EINVAL, ENOATTR, ENOSYS and ENXIO to signal
507 		 * certain conditions:
508 		 *   EINVAL -	Value provided for a keyword that does
509 		 *		not take a value. The value is ignored.
510 		 *   ENOATTR -	Value missing for a keyword that needs
511 		 *		a value. The keyword is ignored.
512 		 *   ENOSYS -	Unsupported keyword encountered. The
513 		 *		keyword is ignored.
514 		 *   ENXIO -	Value provided for a keyword that does
515 		 *		not take a value. The value is ignored.
516 		 */
517 		switch (keyword[0]) {
518 		case 'c':
519 			if (strcmp(keyword, "contents") == 0) {
520 				if (value == NULL) {
521 					error = ENOATTR;
522 					break;
523 				}
524 				node->contents = estrdup(value);
525 			} else
526 				error = ENOSYS;
527 			break;
528 		case 'f':
529 			if (strcmp(keyword, "flags") == 0) {
530 				if (value == NULL) {
531 					error = ENOATTR;
532 					break;
533 				}
534 				flset = flclr = 0;
535 				if (!strtofflags(&value, &flset, &flclr)) {
536 					st->st_flags &= ~flclr;
537 					st->st_flags |= flset;
538 				} else
539 					error = errno;
540 			} else
541 				error = ENOSYS;
542 			break;
543 		case 'g':
544 			if (strcmp(keyword, "gid") == 0) {
545 				if (value == NULL) {
546 					error = ENOATTR;
547 					break;
548 				}
549 				error = read_number(value, 10, &num,
550 				    0, UINT_MAX);
551 				if (!error)
552 					st->st_gid = num;
553 			} else if (strcmp(keyword, "gname") == 0) {
554 				if (value == NULL) {
555 					error = ENOATTR;
556 					break;
557 				}
558 				if (gid_from_group(value, &gid) == 0)
559 					st->st_gid = gid;
560 				else
561 					error = EINVAL;
562 			} else
563 				error = ENOSYS;
564 			break;
565 		case 'l':
566 			if (strcmp(keyword, "link") == 0) {
567 				if (value == NULL) {
568 					error = ENOATTR;
569 					break;
570 				}
571 				node->symlink = emalloc(strlen(value) + 1);
572 				if (node->symlink == NULL) {
573 					error = errno;
574 					break;
575 				}
576 				if (strunvis(node->symlink, value) < 0) {
577 					error = errno;
578 					break;
579 				}
580 			} else
581 				error = ENOSYS;
582 			break;
583 		case 'm':
584 			if (strcmp(keyword, "mode") == 0) {
585 				if (value == NULL) {
586 					error = ENOATTR;
587 					break;
588 				}
589 				if (value[0] >= '0' && value[0] <= '9') {
590 					error = read_number(value, 8, &num,
591 					    0, 07777);
592 					if (!error) {
593 						st->st_mode &= S_IFMT;
594 						st->st_mode |= num;
595 					}
596 				} else {
597 					/* Symbolic mode not supported. */
598 					error = EINVAL;
599 					break;
600 				}
601 			} else
602 				error = ENOSYS;
603 			break;
604 		case 'o':
605 			if (strcmp(keyword, "optional") == 0) {
606 				if (value != NULL)
607 					error = ENXIO;
608 				node->flags |= FSNODE_F_OPTIONAL;
609 			} else
610 				error = ENOSYS;
611 			break;
612 		case 's':
613 			if (strcmp(keyword, "size") == 0) {
614 				if (value == NULL) {
615 					error = ENOATTR;
616 					break;
617 				}
618 				error = read_number(value, 10, &num,
619 				    0, INTMAX_MAX);
620 				if (!error)
621 					st->st_size = num;
622 			} else
623 				error = ENOSYS;
624 			break;
625 		case 't':
626 			if (strcmp(keyword, "time") == 0) {
627 				if (value == NULL) {
628 					error = ENOATTR;
629 					break;
630 				}
631 				p = strchr(value, '.');
632 				if (p != NULL)
633 					*p++ = '\0';
634 				error = read_number(value, 10, &num, 0,
635 				    INTMAX_MAX);
636 				if (error)
637 					break;
638 				st->st_atime = num;
639 				st->st_ctime = num;
640 				st->st_mtime = num;
641 				if (p == NULL)
642 					break;
643 				error = read_number(p, 10, &num, 0,
644 				    INTMAX_MAX);
645 				if (error)
646 					break;
647 				if (num != 0)
648 					error = EINVAL;
649 			} else if (strcmp(keyword, "type") == 0) {
650 				if (value == NULL) {
651 					error = ENOATTR;
652 					break;
653 				}
654 				if (strcmp(value, "dir") == 0)
655 					node->type = S_IFDIR;
656 				else if (strcmp(value, "file") == 0)
657 					node->type = S_IFREG;
658 				else if (strcmp(value, "link") == 0)
659 					node->type = S_IFLNK;
660 				else
661 					error = EINVAL;
662 			} else
663 				error = ENOSYS;
664 			break;
665 		case 'u':
666 			if (strcmp(keyword, "uid") == 0) {
667 				if (value == NULL) {
668 					error = ENOATTR;
669 					break;
670 				}
671 				error = read_number(value, 10, &num,
672 				    0, UINT_MAX);
673 				if (!error)
674 					st->st_uid = num;
675 			} else if (strcmp(keyword, "uname") == 0) {
676 				if (value == NULL) {
677 					error = ENOATTR;
678 					break;
679 				}
680 				if (uid_from_user(value, &uid) == 0)
681 					st->st_uid = uid;
682 				else
683 					error = EINVAL;
684 			} else
685 				error = ENOSYS;
686 			break;
687 		default:
688 			error = ENOSYS;
689 			break;
690 		}
691 
692 		switch (error) {
693 		case EINVAL:
694 			mtree_error("%s: invalid value '%s'", keyword, value);
695 			break;
696 		case ENOATTR:
697 			mtree_error("%s: keyword needs a value", keyword);
698 			break;
699 		case ENOSYS:
700 			mtree_warning("%s: unsupported keyword", keyword);
701 			break;
702 		case ENXIO:
703 			mtree_error("%s: keyword does not take a value",
704 			    keyword);
705 			break;
706 		}
707 	} while (1);
708 
709 	if (error)
710 		return (error);
711 
712 	st->st_mode = (st->st_mode & ~S_IFMT) | node->type;
713 
714 	/* Nothing more to do for the global defaults. */
715 	if (node->name == NULL)
716 		return (0);
717 
718 	/*
719 	 * Be intelligent about the file type.
720 	 */
721 	if (node->contents != NULL) {
722 		if (node->symlink != NULL) {
723 			mtree_error("%s: both link and contents keywords "
724 			    "defined", node->name);
725 			return (0);
726 		}
727 		type = S_IFREG;
728 	} else if (node->type != 0) {
729 		type = node->type;
730 		if (type == S_IFREG) {
731 			/* the named path is the default contents */
732 			node->contents = mtree_file_path(node);
733 		}
734 	} else
735 		type = (node->symlink != NULL) ? S_IFLNK : S_IFDIR;
736 
737 	if (node->type == 0)
738 		node->type = type;
739 
740 	if (node->type != type) {
741 		mtree_error("%s: file type and defined keywords to not match",
742 		    node->name);
743 		return (0);
744 	}
745 
746 	st->st_mode = (st->st_mode & ~S_IFMT) | node->type;
747 
748 	if (node->contents == NULL)
749 		return (0);
750 
751 	name = mtree_resolve(node->contents, &istemp);
752 	if (name == NULL)
753 		return (errno);
754 
755 	if (stat(name, &sb) != 0) {
756 		mtree_error("%s: contents file '%s' not found", node->name,
757 		    name);
758 		free(name);
759 		return (0);
760 	}
761 
762 	/*
763          * Check for hardlinks. If the contents key is used, then the check
764          * will only trigger if the contents file is a link even if it is used
765          * by more than one file
766 	 */
767 	if (sb.st_nlink > 1) {
768 		fsinode *curino;
769 
770 		st->st_ino = sb.st_ino;
771 		st->st_dev = sb.st_dev;
772 		curino = link_check(node->inode);
773 		if (curino != NULL) {
774 			free(node->inode);
775 			node->inode = curino;
776 			node->inode->nlink++;
777 		}
778 	}
779 
780 	free(node->contents);
781 	node->contents = name;
782 	st->st_size = sb.st_size;
783 	return (0);
784 }
785 
786 static int
787 read_mtree_command(FILE *fp)
788 {
789 	char cmd[10];
790 	int error;
791 
792 	error = read_word(fp, cmd, sizeof(cmd));
793 	if (error)
794 		goto out;
795 
796 	error = read_mtree_keywords(fp, &mtree_global);
797 
798  out:
799 	skip_to(fp, "\n");
800 	(void)getc(fp);
801 	return (error);
802 }
803 
804 static int
805 read_mtree_spec1(FILE *fp, bool def, const char *name)
806 {
807 	fsnode *last, *node, *parent;
808 	u_int type;
809 	int error;
810 
811 	assert(name[0] != '\0');
812 
813 	/*
814 	 * Treat '..' specially, because it only changes our current
815 	 * directory. We don't create a node for it. We simply ignore
816 	 * any keywords that may appear on the line as well.
817 	 * Going up a directory is a little non-obvious. A directory
818 	 * node has a corresponding '.' child. The parent of '.' is
819 	 * not the '.' node of the parent directory, but the directory
820 	 * node within the parent to which the child relates. However,
821 	 * going up a directory means we need to find the '.' node to
822 	 * which the directoy node is linked.  This we can do via the
823 	 * first * pointer, because '.' is always the first entry in a
824 	 * directory.
825 	 */
826 	if (IS_DOTDOT(name)) {
827 		/* This deals with NULL pointers as well. */
828 		if (mtree_current == mtree_root) {
829 			mtree_warning("ignoring .. in root directory");
830 			return (0);
831 		}
832 
833 		node = mtree_current;
834 
835 		assert(node != NULL);
836 		assert(IS_DOT(node->name));
837 		assert(node->first == node);
838 
839 		/* Get the corresponding directory node in the parent. */
840 		node = mtree_current->parent;
841 
842 		assert(node != NULL);
843 		assert(!IS_DOT(node->name));
844 
845 		node = node->first;
846 
847 		assert(node != NULL);
848 		assert(IS_DOT(node->name));
849 		assert(node->first == node);
850 
851 		mtree_current = node;
852 		return (0);
853 	}
854 
855 	/*
856 	 * If we don't have a current directory and the first specification
857 	 * (either implicit or defined) is not '.', then we need to create
858 	 * a '.' node first (using a recursive call).
859 	 */
860 	if (!IS_DOT(name) && mtree_current == NULL) {
861 		error = read_mtree_spec1(fp, false, ".");
862 		if (error)
863 			return (error);
864 	}
865 
866 	/*
867 	 * Lookup the name in the current directory (if we have a current
868 	 * directory) to make sure we do not create multiple nodes for the
869 	 * same component. For non-definitions, if we find a node with the
870 	 * same name, simply change the current directory. For definitions
871 	 * more happens.
872 	 */
873 	last = NULL;
874 	node = mtree_current;
875 	while (node != NULL) {
876 		assert(node->first == mtree_current);
877 
878 		if (strcmp(name, node->name) == 0) {
879 			if (def == true) {
880 				if (!dupsok)
881 					mtree_error(
882 					    "duplicate definition of %s",
883 					    name);
884 				else
885 					mtree_warning(
886 					    "duplicate definition of %s",
887 					    name);
888 				return (0);
889 			}
890 
891 			if (node->type != S_IFDIR) {
892 				mtree_error("%s is not a directory", name);
893 				return (0);
894 			}
895 
896 			assert(!IS_DOT(name));
897 
898 			node = node->child;
899 
900 			assert(node != NULL);
901 			assert(IS_DOT(node->name));
902 
903 			mtree_current = node;
904 			return (0);
905 		}
906 
907 		last = node;
908 		node = last->next;
909 	}
910 
911 	parent = (mtree_current != NULL) ? mtree_current->parent : NULL;
912 	type = (def == false || IS_DOT(name)) ? S_IFDIR : 0;
913 	node = create_node(name, type, parent, &mtree_global);
914 	if (node == NULL)
915 		return (ENOMEM);
916 
917 	if (def == true) {
918 		error = read_mtree_keywords(fp, node);
919 		if (error) {
920 			destroy_node(node);
921 			return (error);
922 		}
923 	}
924 
925 	node->first = (mtree_current != NULL) ? mtree_current : node;
926 
927 	if (last != NULL)
928 		last->next = node;
929 
930 	if (node->type != S_IFDIR)
931 		return (0);
932 
933 	if (!IS_DOT(node->name)) {
934 		parent = node;
935 		node = create_node(".", S_IFDIR, parent, parent);
936 		if (node == NULL) {
937 			last->next = NULL;
938 			destroy_node(parent);
939 			return (ENOMEM);
940 		}
941 		parent->child = node;
942 		node->first = node;
943 	}
944 
945 	assert(node != NULL);
946 	assert(IS_DOT(node->name));
947 	assert(node->first == node);
948 
949 	mtree_current = node;
950 	if (mtree_root == NULL)
951 		mtree_root = node;
952 
953 	return (0);
954 }
955 
956 static int
957 read_mtree_spec(FILE *fp)
958 {
959 	char pathspec[PATH_MAX], pathtmp[4*PATH_MAX + 1];
960 	char *cp;
961 	int error;
962 
963 	error = read_word(fp, pathtmp, sizeof(pathtmp));
964 	if (error)
965 		goto out;
966 	if (strnunvis(pathspec, PATH_MAX, pathtmp) == -1) {
967 		error = errno;
968 		goto out;
969 	}
970 	error = 0;
971 
972 	cp = strchr(pathspec, '/');
973 	if (cp != NULL) {
974 		/* Absolute pathname */
975 		mtree_current = mtree_root;
976 
977 		do {
978 			*cp++ = '\0';
979 
980 			/* Disallow '..' as a component. */
981 			if (IS_DOTDOT(pathspec)) {
982 				mtree_error("absolute path cannot contain "
983 				    ".. component");
984 				goto out;
985 			}
986 
987 			/* Ignore multiple adjacent slashes and '.'. */
988 			if (pathspec[0] != '\0' && !IS_DOT(pathspec))
989 				error = read_mtree_spec1(fp, false, pathspec);
990 			memmove(pathspec, cp, strlen(cp) + 1);
991 			cp = strchr(pathspec, '/');
992 		} while (!error && cp != NULL);
993 
994 		/* Disallow '.' and '..' as the last component. */
995 		if (!error && (IS_DOT(pathspec) || IS_DOTDOT(pathspec))) {
996 			mtree_error("absolute path cannot contain . or .. "
997 			    "components");
998 			goto out;
999 		}
1000 	}
1001 
1002 	/* Ignore absolute specfications that end with a slash. */
1003 	if (!error && pathspec[0] != '\0')
1004 		error = read_mtree_spec1(fp, true, pathspec);
1005 
1006  out:
1007 	skip_to(fp, "\n");
1008 	(void)getc(fp);
1009 	return (error);
1010 }
1011 
1012 fsnode *
1013 read_mtree(const char *fname, fsnode *node)
1014 {
1015 	struct mtree_fileinfo *fi;
1016 	FILE *fp;
1017 	int c, error;
1018 
1019 	/* We do not yet support nesting... */
1020 	assert(node == NULL);
1021 
1022 	if (strcmp(fname, "-") == 0)
1023 		fp = stdin;
1024 	else {
1025 		fp = fopen(fname, "r");
1026 		if (fp == NULL)
1027 			err(1, "Can't open `%s'", fname);
1028 	}
1029 
1030 	error = mtree_file_push(fname, fp);
1031 	if (error)
1032 		goto out;
1033 
1034 	memset(&mtree_global, 0, sizeof(mtree_global));
1035 	memset(&mtree_global_inode, 0, sizeof(mtree_global_inode));
1036 	mtree_global.inode = &mtree_global_inode;
1037 	mtree_global_inode.nlink = 1;
1038 	mtree_global_inode.st.st_nlink = 1;
1039 	mtree_global_inode.st.st_atime = mtree_global_inode.st.st_ctime =
1040 	    mtree_global_inode.st.st_mtime = time(NULL);
1041 	errors = warnings = 0;
1042 
1043 	setgroupent(1);
1044 	setpassent(1);
1045 
1046 	mtree_root = node;
1047 	mtree_current = node;
1048 	do {
1049 		/* Start of a new line... */
1050 		fi = SLIST_FIRST(&mtree_fileinfo);
1051 		fi->line++;
1052 
1053 		error = skip_over(fp, " \t");
1054 		if (error)
1055 			break;
1056 
1057 		c = getc(fp);
1058 		if (c == EOF) {
1059 			error = ferror(fp) ? errno : -1;
1060 			break;
1061 		}
1062 
1063 		switch (c) {
1064 		case '\n':		/* empty line */
1065 			error = 0;
1066 			break;
1067 		case '#':		/* comment -- skip to end of line. */
1068 			error = skip_to(fp, "\n");
1069 			if (!error)
1070 				(void)getc(fp);
1071 			break;
1072 		case '/':		/* special commands */
1073 			error = read_mtree_command(fp);
1074 			break;
1075 		default:		/* specification */
1076 			ungetc(c, fp);
1077 			error = read_mtree_spec(fp);
1078 			break;
1079 		}
1080 	} while (!error);
1081 
1082 	endpwent();
1083 	endgrent();
1084 
1085 	if (error <= 0 && (errors || warnings)) {
1086 		warnx("%u error(s) and %u warning(s) in mtree manifest",
1087 		    errors, warnings);
1088 		if (errors)
1089 			exit(1);
1090 	}
1091 
1092  out:
1093 	if (error > 0)
1094 		errc(1, error, "Error reading mtree file");
1095 
1096 	if (fp != stdin)
1097 		fclose(fp);
1098 
1099 	if (mtree_root != NULL)
1100 		return (mtree_root);
1101 
1102 	/* Handle empty specifications. */
1103 	node = create_node(".", S_IFDIR, NULL, &mtree_global);
1104 	node->first = node;
1105 	return (node);
1106 }
1107