xref: /netbsd-src/common/lib/libprop/prop_object.c (revision da9817918ec7e88db2912a2882967c7570a83f47)
1 /*	$NetBSD: prop_object.c,v 1.26 2009/03/30 07:42:51 haad Exp $	*/
2 
3 /*-
4  * Copyright (c) 2006, 2007 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Jason R. Thorpe.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #include <prop/prop_object.h>
33 #include "prop_object_impl.h"
34 
35 #if !defined(_KERNEL) && !defined(_STANDALONE)
36 #include <sys/mman.h>
37 #include <sys/stat.h>
38 #include <errno.h>
39 #include <fcntl.h>
40 #include <limits.h>
41 #include <unistd.h>
42 #endif
43 #include <sys/atomic.h>
44 
45 #ifdef _STANDALONE
46 void *
47 _prop_standalone_calloc(size_t size)
48 {
49 	void *rv;
50 
51 	rv = alloc(size);
52 	if (rv != NULL)
53 		memset(rv, 0, size);
54 
55 	return (rv);
56 }
57 
58 void *
59 _prop_standalone_realloc(void *v, size_t size)
60 {
61 	void *rv;
62 
63 	rv = alloc(size);
64 	if (rv != NULL) {
65 		memcpy(rv, v, size);	/* XXX */
66 		dealloc(v, 0);		/* XXX */
67 	}
68 
69 	return (rv);
70 }
71 #endif /* _STANDALONE */
72 
73 /*
74  * _prop_object_init --
75  *	Initialize an object.  Called when sub-classes create
76  *	an instance.
77  */
78 void
79 _prop_object_init(struct _prop_object *po, const struct _prop_object_type *pot)
80 {
81 
82 	po->po_type = pot;
83 	po->po_refcnt = 1;
84 }
85 
86 /*
87  * _prop_object_fini --
88  *	Finalize an object.  Called when sub-classes destroy
89  *	an instance.
90  */
91 /*ARGSUSED*/
92 void
93 _prop_object_fini(struct _prop_object *po _PROP_ARG_UNUSED)
94 {
95 	/* Nothing to do, currently. */
96 }
97 
98 /*
99  * _prop_object_externalize_start_tag --
100  *	Append an XML-style start tag to the externalize buffer.
101  */
102 bool
103 _prop_object_externalize_start_tag(
104     struct _prop_object_externalize_context *ctx, const char *tag)
105 {
106 	unsigned int i;
107 
108 	for (i = 0; i < ctx->poec_depth; i++) {
109 		if (_prop_object_externalize_append_char(ctx, '\t') == false)
110 			return (false);
111 	}
112 	if (_prop_object_externalize_append_char(ctx, '<') == false ||
113 	    _prop_object_externalize_append_cstring(ctx, tag) == false ||
114 	    _prop_object_externalize_append_char(ctx, '>') == false)
115 		return (false);
116 
117 	return (true);
118 }
119 
120 /*
121  * _prop_object_externalize_end_tag --
122  *	Append an XML-style end tag to the externalize buffer.
123  */
124 bool
125 _prop_object_externalize_end_tag(
126     struct _prop_object_externalize_context *ctx, const char *tag)
127 {
128 
129 	if (_prop_object_externalize_append_char(ctx, '<') == false ||
130 	    _prop_object_externalize_append_char(ctx, '/') == false ||
131 	    _prop_object_externalize_append_cstring(ctx, tag) == false ||
132 	    _prop_object_externalize_append_char(ctx, '>') == false ||
133 	    _prop_object_externalize_append_char(ctx, '\n') == false)
134 		return (false);
135 
136 	return (true);
137 }
138 
139 /*
140  * _prop_object_externalize_empty_tag --
141  *	Append an XML-style empty tag to the externalize buffer.
142  */
143 bool
144 _prop_object_externalize_empty_tag(
145     struct _prop_object_externalize_context *ctx, const char *tag)
146 {
147 	unsigned int i;
148 
149 	for (i = 0; i < ctx->poec_depth; i++) {
150 		if (_prop_object_externalize_append_char(ctx, '\t') == false)
151 			return (false);
152 	}
153 
154 	if (_prop_object_externalize_append_char(ctx, '<') == false ||
155 	    _prop_object_externalize_append_cstring(ctx, tag) == false ||
156 	    _prop_object_externalize_append_char(ctx, '/') == false ||
157 	    _prop_object_externalize_append_char(ctx, '>') == false ||
158 	    _prop_object_externalize_append_char(ctx, '\n') == false)
159 	    	return (false);
160 
161 	return (true);
162 }
163 
164 /*
165  * _prop_object_externalize_append_cstring --
166  *	Append a C string to the externalize buffer.
167  */
168 bool
169 _prop_object_externalize_append_cstring(
170     struct _prop_object_externalize_context *ctx, const char *cp)
171 {
172 
173 	while (*cp != '\0') {
174 		if (_prop_object_externalize_append_char(ctx,
175 						(unsigned char) *cp) == false)
176 			return (false);
177 		cp++;
178 	}
179 
180 	return (true);
181 }
182 
183 /*
184  * _prop_object_externalize_append_encoded_cstring --
185  *	Append an encoded C string to the externalize buffer.
186  */
187 bool
188 _prop_object_externalize_append_encoded_cstring(
189     struct _prop_object_externalize_context *ctx, const char *cp)
190 {
191 
192 	while (*cp != '\0') {
193 		switch (*cp) {
194 		case '<':
195 			if (_prop_object_externalize_append_cstring(ctx,
196 					"&lt;") == false)
197 				return (false);
198 			break;
199 		case '>':
200 			if (_prop_object_externalize_append_cstring(ctx,
201 					"&gt;") == false)
202 				return (false);
203 			break;
204 		case '&':
205 			if (_prop_object_externalize_append_cstring(ctx,
206 					"&amp;") == false)
207 				return (false);
208 			break;
209 		default:
210 			if (_prop_object_externalize_append_char(ctx,
211 					(unsigned char) *cp) == false)
212 				return (false);
213 			break;
214 		}
215 		cp++;
216 	}
217 
218 	return (true);
219 }
220 
221 #define	BUF_EXPAND		256
222 
223 /*
224  * _prop_object_externalize_append_char --
225  *	Append a single character to the externalize buffer.
226  */
227 bool
228 _prop_object_externalize_append_char(
229     struct _prop_object_externalize_context *ctx, unsigned char c)
230 {
231 
232 	_PROP_ASSERT(ctx->poec_capacity != 0);
233 	_PROP_ASSERT(ctx->poec_buf != NULL);
234 	_PROP_ASSERT(ctx->poec_len <= ctx->poec_capacity);
235 
236 	if (ctx->poec_len == ctx->poec_capacity) {
237 		char *cp = _PROP_REALLOC(ctx->poec_buf,
238 					 ctx->poec_capacity + BUF_EXPAND,
239 					 M_TEMP);
240 		if (cp == NULL)
241 			return (false);
242 		ctx->poec_capacity = ctx->poec_capacity + BUF_EXPAND;
243 		ctx->poec_buf = cp;
244 	}
245 
246 	ctx->poec_buf[ctx->poec_len++] = c;
247 
248 	return (true);
249 }
250 
251 /*
252  * _prop_object_externalize_header --
253  *	Append the standard XML header to the externalize buffer.
254  */
255 bool
256 _prop_object_externalize_header(struct _prop_object_externalize_context *ctx)
257 {
258 	static const char _plist_xml_header[] =
259 "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
260 "<!DOCTYPE plist PUBLIC \"-//Apple Computer//DTD PLIST 1.0//EN\" \"http://www.apple.com/DTDs/PropertyList-1.0.dtd\">\n";
261 
262 	if (_prop_object_externalize_append_cstring(ctx,
263 						 _plist_xml_header) == false ||
264 	    _prop_object_externalize_start_tag(ctx,
265 				       "plist version=\"1.0\"") == false ||
266 	    _prop_object_externalize_append_char(ctx, '\n') == false)
267 		return (false);
268 
269 	return (true);
270 }
271 
272 /*
273  * _prop_object_externalize_footer --
274  *	Append the standard XML footer to the externalize buffer.  This
275  *	also NUL-terminates the buffer.
276  */
277 bool
278 _prop_object_externalize_footer(struct _prop_object_externalize_context *ctx)
279 {
280 
281 	if (_prop_object_externalize_end_tag(ctx, "plist") == false ||
282 	    _prop_object_externalize_append_char(ctx, '\0') == false)
283 		return (false);
284 
285 	return (true);
286 }
287 
288 /*
289  * _prop_object_externalize_context_alloc --
290  *	Allocate an externalize context.
291  */
292 struct _prop_object_externalize_context *
293 _prop_object_externalize_context_alloc(void)
294 {
295 	struct _prop_object_externalize_context *ctx;
296 
297 	ctx = _PROP_MALLOC(sizeof(*ctx), M_TEMP);
298 	if (ctx != NULL) {
299 		ctx->poec_buf = _PROP_MALLOC(BUF_EXPAND, M_TEMP);
300 		if (ctx->poec_buf == NULL) {
301 			_PROP_FREE(ctx, M_TEMP);
302 			return (NULL);
303 		}
304 		ctx->poec_len = 0;
305 		ctx->poec_capacity = BUF_EXPAND;
306 		ctx->poec_depth = 0;
307 	}
308 	return (ctx);
309 }
310 
311 /*
312  * _prop_object_externalize_context_free --
313  *	Free an externalize context.
314  */
315 void
316 _prop_object_externalize_context_free(
317 		struct _prop_object_externalize_context *ctx)
318 {
319 
320 	/* Buffer is always freed by the caller. */
321 	_PROP_FREE(ctx, M_TEMP);
322 }
323 
324 /*
325  * _prop_object_internalize_skip_comment --
326  *	Skip the body and end tag of a comment.
327  */
328 static bool
329 _prop_object_internalize_skip_comment(
330 				struct _prop_object_internalize_context *ctx)
331 {
332 	const char *cp = ctx->poic_cp;
333 
334 	while (!_PROP_EOF(*cp)) {
335 		if (cp[0] == '-' &&
336 		    cp[1] == '-' &&
337 		    cp[2] == '>') {
338 			ctx->poic_cp = cp + 3;
339 			return (true);
340 		}
341 		cp++;
342 	}
343 
344 	return (false);		/* ran out of buffer */
345 }
346 
347 /*
348  * _prop_object_internalize_find_tag --
349  *	Find the next tag in an XML stream.  Optionally compare the found
350  *	tag to an expected tag name.  State of the context is undefined
351  *	if this routine returns false.  Upon success, the context points
352  *	to the first octet after the tag.
353  */
354 bool
355 _prop_object_internalize_find_tag(struct _prop_object_internalize_context *ctx,
356 		      const char *tag, _prop_tag_type_t type)
357 {
358 	const char *cp;
359 	size_t taglen;
360 
361 	if (tag != NULL)
362 		taglen = strlen(tag);
363 	else
364 		taglen = 0;
365 
366  start_over:
367 	cp = ctx->poic_cp;
368 
369 	/*
370 	 * Find the start of the tag.
371 	 */
372 	while (_PROP_ISSPACE(*cp))
373 		cp++;
374 	if (_PROP_EOF(*cp))
375 		return (false);
376 
377 	if (*cp != '<')
378 		return (false);
379 
380 	ctx->poic_tag_start = cp++;
381 	if (_PROP_EOF(*cp))
382 		return (false);
383 
384 	if (*cp == '!') {
385 		if (cp[1] != '-' || cp[2] != '-')
386 			return (false);
387 		/*
388 		 * Comment block -- only allowed if we are allowed to
389 		 * return a start tag.
390 		 */
391 		if (type == _PROP_TAG_TYPE_END)
392 			return (false);
393 		ctx->poic_cp = cp + 3;
394 		if (_prop_object_internalize_skip_comment(ctx) == false)
395 			return (false);
396 		goto start_over;
397 	}
398 
399 	if (*cp == '/') {
400 		if (type != _PROP_TAG_TYPE_END &&
401 		    type != _PROP_TAG_TYPE_EITHER)
402 			return (false);
403 		cp++;
404 		if (_PROP_EOF(*cp))
405 			return (false);
406 		ctx->poic_tag_type = _PROP_TAG_TYPE_END;
407 	} else {
408 		if (type != _PROP_TAG_TYPE_START &&
409 		    type != _PROP_TAG_TYPE_EITHER)
410 			return (false);
411 		ctx->poic_tag_type = _PROP_TAG_TYPE_START;
412 	}
413 
414 	ctx->poic_tagname = cp;
415 
416 	while (!_PROP_ISSPACE(*cp) && *cp != '/' && *cp != '>')
417 		cp++;
418 	if (_PROP_EOF(*cp))
419 		return (false);
420 
421 	ctx->poic_tagname_len = cp - ctx->poic_tagname;
422 
423 	/* Make sure this is the tag we're looking for. */
424 	if (tag != NULL &&
425 	    (taglen != ctx->poic_tagname_len ||
426 	     memcmp(tag, ctx->poic_tagname, taglen) != 0))
427 		return (false);
428 
429 	/* Check for empty tag. */
430 	if (*cp == '/') {
431 		if (ctx->poic_tag_type != _PROP_TAG_TYPE_START)
432 			return(false);		/* only valid on start tags */
433 		ctx->poic_is_empty_element = true;
434 		cp++;
435 		if (_PROP_EOF(*cp) || *cp != '>')
436 			return (false);
437 	} else
438 		ctx->poic_is_empty_element = false;
439 
440 	/* Easy case of no arguments. */
441 	if (*cp == '>') {
442 		ctx->poic_tagattr = NULL;
443 		ctx->poic_tagattr_len = 0;
444 		ctx->poic_tagattrval = NULL;
445 		ctx->poic_tagattrval_len = 0;
446 		ctx->poic_cp = cp + 1;
447 		return (true);
448 	}
449 
450 	_PROP_ASSERT(!_PROP_EOF(*cp));
451 	cp++;
452 	if (_PROP_EOF(*cp))
453 		return (false);
454 
455 	while (_PROP_ISSPACE(*cp))
456 		cp++;
457 	if (_PROP_EOF(*cp))
458 		return (false);
459 
460 	ctx->poic_tagattr = cp;
461 
462 	while (!_PROP_ISSPACE(*cp) && *cp != '=')
463 		cp++;
464 	if (_PROP_EOF(*cp))
465 		return (false);
466 
467 	ctx->poic_tagattr_len = cp - ctx->poic_tagattr;
468 
469 	cp++;
470 	if (*cp != '\"')
471 		return (false);
472 	cp++;
473 	if (_PROP_EOF(*cp))
474 		return (false);
475 
476 	ctx->poic_tagattrval = cp;
477 	while (*cp != '\"')
478 		cp++;
479 	if (_PROP_EOF(*cp))
480 		return (false);
481 	ctx->poic_tagattrval_len = cp - ctx->poic_tagattrval;
482 
483 	cp++;
484 	if (*cp != '>')
485 		return (false);
486 
487 	ctx->poic_cp = cp + 1;
488 	return (true);
489 }
490 
491 /*
492  * _prop_object_internalize_decode_string --
493  *	Decode an encoded string.
494  */
495 bool
496 _prop_object_internalize_decode_string(
497 				struct _prop_object_internalize_context *ctx,
498 				char *target, size_t targsize, size_t *sizep,
499 				const char **cpp)
500 {
501 	const char *src;
502 	size_t tarindex;
503 	char c;
504 
505 	tarindex = 0;
506 	src = ctx->poic_cp;
507 
508 	for (;;) {
509 		if (_PROP_EOF(*src))
510 			return (false);
511 		if (*src == '<') {
512 			break;
513 		}
514 
515 		if ((c = *src) == '&') {
516 			if (src[1] == 'a' &&
517 			    src[2] == 'm' &&
518 			    src[3] == 'p' &&
519 			    src[4] == ';') {
520 			    	c = '&';
521 				src += 5;
522 			} else if (src[1] == 'l' &&
523 				   src[2] == 't' &&
524 				   src[3] == ';') {
525 				c = '<';
526 				src += 4;
527 			} else if (src[1] == 'g' &&
528 				   src[2] == 't' &&
529 				   src[3] == ';') {
530 				c = '>';
531 				src += 4;
532 			} else if (src[1] == 'a' &&
533 				   src[2] == 'p' &&
534 				   src[3] == 'o' &&
535 				   src[4] == 's' &&
536 				   src[5] == ';') {
537 				c = '\'';
538 				src += 6;
539 			} else if (src[1] == 'q' &&
540 				   src[2] == 'u' &&
541 				   src[3] == 'o' &&
542 				   src[4] == 't' &&
543 				   src[5] == ';') {
544 				c = '\"';
545 				src += 6;
546 			} else
547 				return (false);
548 		} else
549 			src++;
550 		if (target) {
551 			if (tarindex >= targsize)
552 				return (false);
553 			target[tarindex] = c;
554 		}
555 		tarindex++;
556 	}
557 
558 	_PROP_ASSERT(*src == '<');
559 	if (sizep != NULL)
560 		*sizep = tarindex;
561 	if (cpp != NULL)
562 		*cpp = src;
563 
564 	return (true);
565 }
566 
567 /*
568  * _prop_object_internalize_match --
569  *	Returns true if the two character streams match.
570  */
571 bool
572 _prop_object_internalize_match(const char *str1, size_t len1,
573 			       const char *str2, size_t len2)
574 {
575 
576 	return (len1 == len2 && memcmp(str1, str2, len1) == 0);
577 }
578 
579 #define	INTERNALIZER(t, f)			\
580 {	t,	sizeof(t) - 1,		f	}
581 
582 static const struct _prop_object_internalizer {
583 	const char			*poi_tag;
584 	size_t				poi_taglen;
585 	prop_object_internalizer_t	poi_intern;
586 } _prop_object_internalizer_table[] = {
587 	INTERNALIZER("array", _prop_array_internalize),
588 
589 	INTERNALIZER("true", _prop_bool_internalize),
590 	INTERNALIZER("false", _prop_bool_internalize),
591 
592 	INTERNALIZER("data", _prop_data_internalize),
593 
594 	INTERNALIZER("dict", _prop_dictionary_internalize),
595 
596 	INTERNALIZER("integer", _prop_number_internalize),
597 
598 	INTERNALIZER("string", _prop_string_internalize),
599 
600 	{ 0, 0, NULL }
601 };
602 
603 #undef INTERNALIZER
604 
605 /*
606  * _prop_object_internalize_by_tag --
607  *	Determine the object type from the tag in the context and
608  *	internalize it.
609  */
610 prop_object_t
611 _prop_object_internalize_by_tag(struct _prop_object_internalize_context *ctx)
612 {
613 	const struct _prop_object_internalizer *poi;
614 	prop_object_t obj, parent_obj;
615 	void *data, *iter;
616 	prop_object_internalizer_continue_t iter_func;
617 	struct _prop_stack stack;
618 
619 	_prop_stack_init(&stack);
620 
621 match_start:
622 	for (poi = _prop_object_internalizer_table;
623 	     poi->poi_tag != NULL; poi++) {
624 		if (_prop_object_internalize_match(ctx->poic_tagname,
625 						   ctx->poic_tagname_len,
626 						   poi->poi_tag,
627 						   poi->poi_taglen))
628 			break;
629 	}
630 	if ((poi == NULL) || (poi->poi_tag == NULL)) {
631 		while (_prop_stack_pop(&stack, &obj, &iter, &data, NULL)) {
632 			iter_func = (prop_object_internalizer_continue_t)iter;
633 			(*iter_func)(&stack, &obj, ctx, data, NULL);
634 		}
635 
636 		return (NULL);
637 	}
638 
639 	obj = NULL;
640 	if (!(*poi->poi_intern)(&stack, &obj, ctx))
641 		goto match_start;
642 
643 	parent_obj = obj;
644 	while (_prop_stack_pop(&stack, &parent_obj, &iter, &data, NULL)) {
645 		iter_func = (prop_object_internalizer_continue_t)iter;
646 		if (!(*iter_func)(&stack, &parent_obj, ctx, data, obj))
647 			goto match_start;
648 		obj = parent_obj;
649 	}
650 
651 	return (parent_obj);
652 }
653 
654 prop_object_t
655 _prop_generic_internalize(const char *xml, const char *master_tag)
656 {
657 	prop_object_t obj = NULL;
658 	struct _prop_object_internalize_context *ctx;
659 
660 	ctx = _prop_object_internalize_context_alloc(xml);
661 	if (ctx == NULL)
662 		return (NULL);
663 
664 	/* We start with a <plist> tag. */
665 	if (_prop_object_internalize_find_tag(ctx, "plist",
666 					      _PROP_TAG_TYPE_START) == false)
667 		goto out;
668 
669 	/* Plist elements cannot be empty. */
670 	if (ctx->poic_is_empty_element)
671 		goto out;
672 
673 	/*
674 	 * We don't understand any plist attributes, but Apple XML
675 	 * property lists often have a "version" attribute.  If we
676 	 * see that one, we simply ignore it.
677 	 */
678 	if (ctx->poic_tagattr != NULL &&
679 	    !_PROP_TAGATTR_MATCH(ctx, "version"))
680 		goto out;
681 
682 	/* Next we expect to see opening master_tag. */
683 	if (_prop_object_internalize_find_tag(ctx, master_tag,
684 					      _PROP_TAG_TYPE_START) == false)
685 		goto out;
686 
687 	obj = _prop_object_internalize_by_tag(ctx);
688 	if (obj == NULL)
689 		goto out;
690 
691 	/*
692 	 * We've advanced past the closing master_tag.
693 	 * Now we want </plist>.
694 	 */
695 	if (_prop_object_internalize_find_tag(ctx, "plist",
696 					      _PROP_TAG_TYPE_END) == false) {
697 		prop_object_release(obj);
698 		obj = NULL;
699 	}
700 
701  out:
702  	_prop_object_internalize_context_free(ctx);
703 	return (obj);
704 }
705 
706 /*
707  * _prop_object_internalize_context_alloc --
708  *	Allocate an internalize context.
709  */
710 struct _prop_object_internalize_context *
711 _prop_object_internalize_context_alloc(const char *xml)
712 {
713 	struct _prop_object_internalize_context *ctx;
714 
715 	ctx = _PROP_MALLOC(sizeof(struct _prop_object_internalize_context),
716 			   M_TEMP);
717 	if (ctx == NULL)
718 		return (NULL);
719 
720 	ctx->poic_xml = ctx->poic_cp = xml;
721 
722 	/*
723 	 * Skip any whitespace and XML preamble stuff that we don't
724 	 * know about / care about.
725 	 */
726 	for (;;) {
727 		while (_PROP_ISSPACE(*xml))
728 			xml++;
729 		if (_PROP_EOF(*xml) || *xml != '<')
730 			goto bad;
731 
732 #define	MATCH(str)	(memcmp(&xml[1], str, sizeof(str) - 1) == 0)
733 
734 		/*
735 		 * Skip over the XML preamble that Apple XML property
736 		 * lists usually include at the top of the file.
737 		 */
738 		if (MATCH("?xml ") ||
739 		    MATCH("!DOCTYPE plist")) {
740 			while (*xml != '>' && !_PROP_EOF(*xml))
741 				xml++;
742 			if (_PROP_EOF(*xml))
743 				goto bad;
744 			xml++;	/* advance past the '>' */
745 			continue;
746 		}
747 
748 		if (MATCH("<!--")) {
749 			ctx->poic_cp = xml + 4;
750 			if (_prop_object_internalize_skip_comment(ctx) == false)
751 				goto bad;
752 			xml = ctx->poic_cp;
753 			continue;
754 		}
755 
756 #undef MATCH
757 
758 		/*
759 		 * We don't think we should skip it, so let's hope we can
760 		 * parse it.
761 		 */
762 		break;
763 	}
764 
765 	ctx->poic_cp = xml;
766 	return (ctx);
767  bad:
768 	_PROP_FREE(ctx, M_TEMP);
769 	return (NULL);
770 }
771 
772 /*
773  * _prop_object_internalize_context_free --
774  *	Free an internalize context.
775  */
776 void
777 _prop_object_internalize_context_free(
778 		struct _prop_object_internalize_context *ctx)
779 {
780 
781 	_PROP_FREE(ctx, M_TEMP);
782 }
783 
784 #if !defined(_KERNEL) && !defined(_STANDALONE)
785 /*
786  * _prop_object_externalize_file_dirname --
787  *	dirname(3), basically.  We have to roll our own because the
788  *	system dirname(3) isn't reentrant.
789  */
790 static void
791 _prop_object_externalize_file_dirname(const char *path, char *result)
792 {
793 	const char *lastp;
794 	size_t len;
795 
796 	/*
797 	 * If `path' is a NULL pointer or points to an empty string,
798 	 * return ".".
799 	 */
800 	if (path == NULL || *path == '\0')
801 		goto singledot;
802 
803 	/* String trailing slashes, if any. */
804 	lastp = path + strlen(path) - 1;
805 	while (lastp != path && *lastp == '/')
806 		lastp--;
807 
808 	/* Terminate path at the last occurrence of '/'. */
809 	do {
810 		if (*lastp == '/') {
811 			/* Strip trailing slashes, if any. */
812 			while (lastp != path && *lastp == '/')
813 				lastp--;
814 
815 			/* ...and copy the result into the result buffer. */
816 			len = (lastp - path) + 1 /* last char */;
817 			if (len > (PATH_MAX - 1))
818 				len = PATH_MAX - 1;
819 
820 			memcpy(result, path, len);
821 			result[len] = '\0';
822 			return;
823 		}
824 	} while (--lastp >= path);
825 
826  	/* No /'s found, return ".". */
827  singledot:
828 	strcpy(result, ".");
829 }
830 
831 /*
832  * _prop_object_externalize_write_file --
833  *	Write an externalized dictionary to the specified file.
834  *	The file is written atomically from the caller's perspective,
835  *	and the mode set to 0666 modified by the caller's umask.
836  */
837 bool
838 _prop_object_externalize_write_file(const char *fname, const char *xml,
839     size_t len)
840 {
841 	char tname[PATH_MAX];
842 	int fd;
843 	int save_errno;
844 	mode_t myumask;
845 
846 	if (len > SSIZE_MAX) {
847 		errno = EFBIG;
848 		return (false);
849 	}
850 
851 	/*
852 	 * Get the directory name where the file is to be written
853 	 * and create the temporary file.
854 	 */
855 	_prop_object_externalize_file_dirname(fname, tname);
856 	if (strlcat(tname, "/.plistXXXXXX", sizeof(tname)) >= sizeof(tname)) {
857 		errno = ENAMETOOLONG;
858 		return (false);
859 	}
860 	if ((fd = mkstemp(tname)) == -1)
861 		return (false);
862 
863 	if (write(fd, xml, len) != (ssize_t)len)
864 		goto bad;
865 
866 	if (fsync(fd) == -1)
867 		goto bad;
868 
869 	myumask = umask(0);
870 	(void)umask(myumask);
871 	if (fchmod(fd, 0666 & ~myumask) == -1)
872 		goto bad;
873 
874 	(void) close(fd);
875 	fd = -1;
876 
877 	if (rename(tname, fname) == -1)
878 		goto bad;
879 
880 	return (true);
881 
882  bad:
883 	save_errno = errno;
884 	if (fd != -1)
885 		(void) close(fd);
886 	(void) unlink(tname);
887 	errno = save_errno;
888 	return (false);
889 }
890 
891 /*
892  * _prop_object_internalize_map_file --
893  *	Map a file for the purpose of internalizing it.
894  */
895 struct _prop_object_internalize_mapped_file *
896 _prop_object_internalize_map_file(const char *fname)
897 {
898 	struct stat sb;
899 	struct _prop_object_internalize_mapped_file *mf;
900 	size_t pgsize = (size_t)sysconf(_SC_PAGESIZE);
901 	size_t pgmask = pgsize - 1;
902 	bool need_guard = false;
903 	int fd;
904 
905 	mf = _PROP_MALLOC(sizeof(*mf), M_TEMP);
906 	if (mf == NULL)
907 		return (NULL);
908 
909 	fd = open(fname, O_RDONLY, 0400);
910 	if (fd == -1) {
911 		_PROP_FREE(mf, M_TEMP);
912 		return (NULL);
913 	}
914 
915 	if (fstat(fd, &sb) == -1) {
916 		(void) close(fd);
917 		_PROP_FREE(mf, M_TEMP);
918 		return (NULL);
919 	}
920 	mf->poimf_mapsize = ((size_t)sb.st_size + pgmask) & ~pgmask;
921 	if (mf->poimf_mapsize < (size_t)sb.st_size) {
922 		(void) close(fd);
923 		_PROP_FREE(mf, M_TEMP);
924 		return (NULL);
925 	}
926 
927 	/*
928 	 * If the file length is an integral number of pages, then we
929 	 * need to map a guard page at the end in order to provide the
930 	 * necessary NUL-termination of the buffer.
931 	 */
932 	if ((sb.st_size & pgmask) == 0)
933 		need_guard = true;
934 
935 	mf->poimf_xml = mmap(NULL, need_guard ? mf->poimf_mapsize + pgsize
936 			    		      : mf->poimf_mapsize,
937 			    PROT_READ, MAP_FILE|MAP_SHARED, fd, (off_t)0);
938 	(void) close(fd);
939 	if (mf->poimf_xml == MAP_FAILED) {
940 		_PROP_FREE(mf, M_TEMP);
941 		return (NULL);
942 	}
943 	(void) madvise(mf->poimf_xml, mf->poimf_mapsize, MADV_SEQUENTIAL);
944 
945 	if (need_guard) {
946 		if (mmap(mf->poimf_xml + mf->poimf_mapsize,
947 			 pgsize, PROT_READ,
948 			 MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1,
949 			 (off_t)0) == MAP_FAILED) {
950 			(void) munmap(mf->poimf_xml, mf->poimf_mapsize);
951 			_PROP_FREE(mf, M_TEMP);
952 			return (NULL);
953 		}
954 		mf->poimf_mapsize += pgsize;
955 	}
956 
957 	return (mf);
958 }
959 
960 /*
961  * _prop_object_internalize_unmap_file --
962  *	Unmap a file previously mapped for internalizing.
963  */
964 void
965 _prop_object_internalize_unmap_file(
966     struct _prop_object_internalize_mapped_file *mf)
967 {
968 
969 	(void) madvise(mf->poimf_xml, mf->poimf_mapsize, MADV_DONTNEED);
970 	(void) munmap(mf->poimf_xml, mf->poimf_mapsize);
971 	_PROP_FREE(mf, M_TEMP);
972 }
973 #endif /* !_KERNEL && !_STANDALONE */
974 
975 /*
976  * prop_object_retain --
977  *	Increment the reference count on an object.
978  */
979 void
980 prop_object_retain(prop_object_t obj)
981 {
982 	struct _prop_object *po = obj;
983 	uint32_t ncnt;
984 
985 	ncnt = atomic_inc_32_nv(&po->po_refcnt);
986 	_PROP_ASSERT(ncnt != 0);
987 }
988 
989 /*
990  * prop_object_release_emergency
991  *	A direct free with prop_object_release failed.
992  *	Walk down the tree until a leaf is found and
993  *	free that. Do not recurse to avoid stack overflows.
994  *
995  *	This is a slow edge condition, but necessary to
996  *	guarantee that an object can always be freed.
997  */
998 static void
999 prop_object_release_emergency(prop_object_t obj)
1000 {
1001 	struct _prop_object *po;
1002 	void (*unlock)(void);
1003 	prop_object_t parent = NULL;
1004 	uint32_t ocnt;
1005 
1006 	for (;;) {
1007 		po = obj;
1008 		_PROP_ASSERT(obj);
1009 
1010 		if (po->po_type->pot_lock != NULL)
1011 		po->po_type->pot_lock();
1012 
1013 		/* Save pointerto unlock function */
1014 		unlock = po->po_type->pot_unlock;
1015 
1016 		/* Dance a bit to make sure we always get the non-racy ocnt */
1017 		ocnt = atomic_dec_32_nv(&po->po_refcnt);
1018 		ocnt++;
1019 		_PROP_ASSERT(ocnt != 0);
1020 
1021 		if (ocnt != 1) {
1022 			if (unlock != NULL)
1023 				unlock();
1024 			break;
1025 		}
1026 
1027 		_PROP_ASSERT(po->po_type);
1028 		if ((po->po_type->pot_free)(NULL, &obj) ==
1029 		    _PROP_OBJECT_FREE_DONE) {
1030 			if (unlock != NULL)
1031 				unlock();
1032 			break;
1033 		}
1034 
1035 		if (unlock != NULL)
1036 			unlock();
1037 
1038 		parent = po;
1039 		atomic_inc_32(&po->po_refcnt);
1040 	}
1041 	_PROP_ASSERT(parent);
1042 	/* One object was just freed. */
1043 	po = parent;
1044 	(*po->po_type->pot_emergency_free)(parent);
1045 }
1046 
1047 /*
1048  * prop_object_release --
1049  *	Decrement the reference count on an object.
1050  *
1051  *	Free the object if we are releasing the final
1052  *	reference.
1053  */
1054 void
1055 prop_object_release(prop_object_t obj)
1056 {
1057 	struct _prop_object *po;
1058 	struct _prop_stack stack;
1059 	void (*unlock)(void);
1060 	int ret;
1061 	uint32_t ocnt;
1062 
1063 	_prop_stack_init(&stack);
1064 
1065 	do {
1066 		do {
1067 			po = obj;
1068 			_PROP_ASSERT(obj);
1069 
1070 			if (po->po_type->pot_lock != NULL)
1071 				po->po_type->pot_lock();
1072 
1073 			/* Save pointer to object unlock function */
1074 			unlock = po->po_type->pot_unlock;
1075 
1076 			ocnt = atomic_dec_32_nv(&po->po_refcnt);
1077 			ocnt++;
1078 			_PROP_ASSERT(ocnt != 0);
1079 
1080 			if (ocnt != 1) {
1081 				ret = 0;
1082 				if (unlock != NULL)
1083 					unlock();
1084 				break;
1085 			}
1086 
1087 			ret = (po->po_type->pot_free)(&stack, &obj);
1088 
1089 			if (unlock != NULL)
1090 				unlock();
1091 
1092 			if (ret == _PROP_OBJECT_FREE_DONE)
1093 				break;
1094 
1095 			atomic_inc_32(&po->po_refcnt);
1096 		} while (ret == _PROP_OBJECT_FREE_RECURSE);
1097 		if (ret == _PROP_OBJECT_FREE_FAILED)
1098 			prop_object_release_emergency(obj);
1099 	} while (_prop_stack_pop(&stack, &obj, NULL, NULL, NULL));
1100 }
1101 
1102 /*
1103  * prop_object_type --
1104  *	Return the type of an object.
1105  */
1106 prop_type_t
1107 prop_object_type(prop_object_t obj)
1108 {
1109 	struct _prop_object *po = obj;
1110 
1111 	if (obj == NULL)
1112 		return (PROP_TYPE_UNKNOWN);
1113 
1114 	return (po->po_type->pot_type);
1115 }
1116 
1117 /*
1118  * prop_object_equals --
1119  *	Returns true if thw two objects are equivalent.
1120  */
1121 bool
1122 prop_object_equals(prop_object_t obj1, prop_object_t obj2)
1123 {
1124 	return (prop_object_equals_with_error(obj1, obj2, NULL));
1125 }
1126 
1127 bool
1128 prop_object_equals_with_error(prop_object_t obj1, prop_object_t obj2,
1129     bool *error_flag)
1130 {
1131 	struct _prop_object *po1;
1132 	struct _prop_object *po2;
1133 	void *stored_pointer1, *stored_pointer2;
1134 	prop_object_t next_obj1, next_obj2;
1135 	struct _prop_stack stack;
1136 	_prop_object_equals_rv_t ret;
1137 
1138 	_prop_stack_init(&stack);
1139 	if (error_flag)
1140 		*error_flag = false;
1141 
1142  start_subtree:
1143 	stored_pointer1 = NULL;
1144 	stored_pointer2 = NULL;
1145 	po1 = obj1;
1146 	po2 = obj2;
1147 
1148 	if (po1->po_type != po2->po_type)
1149 		return (false);
1150 
1151  continue_subtree:
1152 	ret = (*po1->po_type->pot_equals)(obj1, obj2,
1153 					  &stored_pointer1, &stored_pointer2,
1154 					  &next_obj1, &next_obj2);
1155 	if (ret == _PROP_OBJECT_EQUALS_FALSE)
1156 		goto finish;
1157 	if (ret == _PROP_OBJECT_EQUALS_TRUE) {
1158 		if (!_prop_stack_pop(&stack, &obj1, &obj2,
1159 				     &stored_pointer1, &stored_pointer2))
1160 			return true;
1161 		goto continue_subtree;
1162 	}
1163 	_PROP_ASSERT(ret == _PROP_OBJECT_EQUALS_RECURSE);
1164 
1165 	if (!_prop_stack_push(&stack, obj1, obj2,
1166 			      stored_pointer1, stored_pointer2)) {
1167 		if (error_flag)
1168 			*error_flag = true;
1169 		goto finish;
1170 	}
1171 	obj1 = next_obj1;
1172 	obj2 = next_obj2;
1173 	goto start_subtree;
1174 
1175 finish:
1176 	while (_prop_stack_pop(&stack, &obj1, &obj2, NULL, NULL)) {
1177 		po1 = obj1;
1178 		(*po1->po_type->pot_equals_finish)(obj1, obj2);
1179 	}
1180 	return (false);
1181 }
1182 
1183 /*
1184  * prop_object_iterator_next --
1185  *	Return the next item during an iteration.
1186  */
1187 prop_object_t
1188 prop_object_iterator_next(prop_object_iterator_t pi)
1189 {
1190 
1191 	return ((*pi->pi_next_object)(pi));
1192 }
1193 
1194 /*
1195  * prop_object_iterator_reset --
1196  *	Reset the iterator to the first object so as to restart
1197  *	iteration.
1198  */
1199 void
1200 prop_object_iterator_reset(prop_object_iterator_t pi)
1201 {
1202 
1203 	(*pi->pi_reset)(pi);
1204 }
1205 
1206 /*
1207  * prop_object_iterator_release --
1208  *	Release the object iterator.
1209  */
1210 void
1211 prop_object_iterator_release(prop_object_iterator_t pi)
1212 {
1213 
1214 	prop_object_release(pi->pi_obj);
1215 	_PROP_FREE(pi, M_TEMP);
1216 }
1217