xref: /illumos-gate/usr/src/cmd/mandoc/mansearch.c (revision f22cbd2db87ae3945ed6a9166f8b9d61b65c6ab9) 
1 /*	$Id: mansearch.c,v 1.76 2017/08/02 13:29:04 schwarze Exp $ */
2 /*
3  * Copyright (c) 2012 Kristaps Dzonsons <kristaps@bsd.lv>
4  * Copyright (c) 2013-2017 Ingo Schwarze <schwarze@openbsd.org>
5  *
6  * Permission to use, copy, modify, and distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 #include "config.h"
19 
20 #include <sys/mman.h>
21 #include <sys/types.h>
22 
23 #include <assert.h>
24 #if HAVE_ERR
25 #include <err.h>
26 #endif
27 #include <errno.h>
28 #include <fcntl.h>
29 #include <glob.h>
30 #include <limits.h>
31 #include <regex.h>
32 #include <stdio.h>
33 #include <stdint.h>
34 #include <stddef.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <unistd.h>
38 
39 #include "mandoc.h"
40 #include "mandoc_aux.h"
41 #include "mandoc_ohash.h"
42 #include "manconf.h"
43 #include "mansearch.h"
44 #include "dbm.h"
45 
46 struct	expr {
47 	/* Used for terms: */
48 	struct dbm_match match;   /* Match type and expression. */
49 	uint64_t	 bits;    /* Type mask. */
50 	/* Used for OR and AND groups: */
51 	struct expr	*next;    /* Next child in the parent group. */
52 	struct expr	*child;   /* First child in this group. */
53 	enum { EXPR_TERM, EXPR_OR, EXPR_AND } type;
54 };
55 
56 const char *const mansearch_keynames[KEY_MAX] = {
57 	"arch",	"sec",	"Xr",	"Ar",	"Fa",	"Fl",	"Dv",	"Fn",
58 	"Ic",	"Pa",	"Cm",	"Li",	"Em",	"Cd",	"Va",	"Ft",
59 	"Tn",	"Er",	"Ev",	"Sy",	"Sh",	"In",	"Ss",	"Ox",
60 	"An",	"Mt",	"St",	"Bx",	"At",	"Nx",	"Fx",	"Lk",
61 	"Ms",	"Bsx",	"Dx",	"Rs",	"Vt",	"Lb",	"Nm",	"Nd"
62 };
63 
64 
65 static	struct ohash	*manmerge(struct expr *, struct ohash *);
66 static	struct ohash	*manmerge_term(struct expr *, struct ohash *);
67 static	struct ohash	*manmerge_or(struct expr *, struct ohash *);
68 static	struct ohash	*manmerge_and(struct expr *, struct ohash *);
69 static	char		*buildnames(const struct dbm_page *);
70 static	char		*buildoutput(size_t, struct dbm_page *);
71 static	size_t		 lstlen(const char *, size_t);
72 static	void		 lstcat(char *, size_t *, const char *, const char *);
73 static	int		 lstmatch(const char *, const char *);
74 static	struct expr	*exprcomp(const struct mansearch *,
75 				int, char *[], int *);
76 static	struct expr	*expr_and(const struct mansearch *,
77 				int, char *[], int *);
78 static	struct expr	*exprterm(const struct mansearch *,
79 				int, char *[], int *);
80 static	void		 exprfree(struct expr *);
81 static	int		 manpage_compare(const void *, const void *);
82 
83 
84 int
85 mansearch(const struct mansearch *search,
86 		const struct manpaths *paths,
87 		int argc, char *argv[],
88 		struct manpage **res, size_t *sz)
89 {
90 	char		 buf[PATH_MAX];
91 	struct dbm_res	*rp;
92 	struct expr	*e;
93 	struct dbm_page	*page;
94 	struct manpage	*mpage;
95 	struct ohash	*htab;
96 	size_t		 cur, i, maxres, outkey;
97 	unsigned int	 slot;
98 	int		 argi, chdir_status, getcwd_status, im;
99 
100 	argi = 0;
101 	if ((e = exprcomp(search, argc, argv, &argi)) == NULL) {
102 		*sz = 0;
103 		return 0;
104 	}
105 
106 	cur = maxres = 0;
107 	if (res != NULL)
108 		*res = NULL;
109 
110 	outkey = KEY_Nd;
111 	if (search->outkey != NULL)
112 		for (im = 0; im < KEY_MAX; im++)
113 			if (0 == strcasecmp(search->outkey,
114 			    mansearch_keynames[im])) {
115 				outkey = im;
116 				break;
117 			}
118 
119 	/*
120 	 * Remember the original working directory, if possible.
121 	 * This will be needed if the second or a later directory
122 	 * is given as a relative path.
123 	 * Do not error out if the current directory is not
124 	 * searchable: Maybe it won't be needed after all.
125 	 */
126 
127 	if (getcwd(buf, PATH_MAX) == NULL) {
128 		getcwd_status = 0;
129 		(void)strlcpy(buf, strerror(errno), sizeof(buf));
130 	} else
131 		getcwd_status = 1;
132 
133 	/*
134 	 * Loop over the directories (containing databases) for us to
135 	 * search.
136 	 * Don't let missing/bad databases/directories phase us.
137 	 * In each, try to open the resident database and, if it opens,
138 	 * scan it for our match expression.
139 	 */
140 
141 	chdir_status = 0;
142 	for (i = 0; i < paths->sz; i++) {
143 		if (chdir_status && paths->paths[i][0] != '/') {
144 			if ( ! getcwd_status) {
145 				warnx("%s: getcwd: %s", paths->paths[i], buf);
146 				continue;
147 			} else if (chdir(buf) == -1) {
148 				warn("%s", buf);
149 				continue;
150 			}
151 		}
152 		if (chdir(paths->paths[i]) == -1) {
153 			warn("%s", paths->paths[i]);
154 			continue;
155 		}
156 		chdir_status = 1;
157 
158 		if (dbm_open(MANDOC_DB) == -1) {
159 			if (errno != ENOENT)
160 				warn("%s/%s", paths->paths[i], MANDOC_DB);
161 			continue;
162 		}
163 
164 		if ((htab = manmerge(e, NULL)) == NULL) {
165 			dbm_close();
166 			continue;
167 		}
168 
169 		for (rp = ohash_first(htab, &slot); rp != NULL;
170 		    rp = ohash_next(htab, &slot)) {
171 			page = dbm_page_get(rp->page);
172 
173 			if (lstmatch(search->sec, page->sect) == 0 ||
174 			    lstmatch(search->arch, page->arch) == 0 ||
175 			    (search->argmode == ARG_NAME &&
176 			     rp->bits <= (int32_t)(NAME_SYN & NAME_MASK)))
177 				continue;
178 
179 			if (res == NULL) {
180 				cur = 1;
181 				break;
182 			}
183 			if (cur + 1 > maxres) {
184 				maxres += 1024;
185 				*res = mandoc_reallocarray(*res,
186 				    maxres, sizeof(**res));
187 			}
188 			mpage = *res + cur;
189 			mandoc_asprintf(&mpage->file, "%s/%s",
190 			    paths->paths[i], page->file + 1);
191 			mpage->names = buildnames(page);
192 			mpage->output = buildoutput(outkey, page);
193 			mpage->ipath = i;
194 			mpage->bits = rp->bits;
195 			mpage->sec = *page->sect - '0';
196 			if (mpage->sec < 0 || mpage->sec > 9)
197 				mpage->sec = 10;
198 			mpage->form = *page->file;
199 			free(rp);
200 			cur++;
201 		}
202 		ohash_delete(htab);
203 		free(htab);
204 		dbm_close();
205 
206 		/*
207 		 * In man(1) mode, prefer matches in earlier trees
208 		 * over matches in later trees.
209 		 */
210 
211 		if (cur && search->firstmatch)
212 			break;
213 	}
214 	if (res != NULL)
215 		qsort(*res, cur, sizeof(struct manpage), manpage_compare);
216 	if (chdir_status && getcwd_status && chdir(buf) == -1)
217 		warn("%s", buf);
218 	exprfree(e);
219 	*sz = cur;
220 	return res != NULL || cur;
221 }
222 
223 /*
224  * Merge the results for the expression tree rooted at e
225  * into the the result list htab.
226  */
227 static struct ohash *
228 manmerge(struct expr *e, struct ohash *htab)
229 {
230 	switch (e->type) {
231 	case EXPR_TERM:
232 		return manmerge_term(e, htab);
233 	case EXPR_OR:
234 		return manmerge_or(e->child, htab);
235 	case EXPR_AND:
236 		return manmerge_and(e->child, htab);
237 	default:
238 		abort();
239 	}
240 }
241 
242 static struct ohash *
243 manmerge_term(struct expr *e, struct ohash *htab)
244 {
245 	struct dbm_res	 res, *rp;
246 	uint64_t	 ib;
247 	unsigned int	 slot;
248 	int		 im;
249 
250 	if (htab == NULL) {
251 		htab = mandoc_malloc(sizeof(*htab));
252 		mandoc_ohash_init(htab, 4, offsetof(struct dbm_res, page));
253 	}
254 
255 	for (im = 0, ib = 1; im < KEY_MAX; im++, ib <<= 1) {
256 		if ((e->bits & ib) == 0)
257 			continue;
258 
259 		switch (ib) {
260 		case TYPE_arch:
261 			dbm_page_byarch(&e->match);
262 			break;
263 		case TYPE_sec:
264 			dbm_page_bysect(&e->match);
265 			break;
266 		case TYPE_Nm:
267 			dbm_page_byname(&e->match);
268 			break;
269 		case TYPE_Nd:
270 			dbm_page_bydesc(&e->match);
271 			break;
272 		default:
273 			dbm_page_bymacro(im - 2, &e->match);
274 			break;
275 		}
276 
277 		/*
278 		 * When hashing for deduplication, use the unique
279 		 * page ID itself instead of a hash function;
280 		 * that is quite efficient.
281 		 */
282 
283 		for (;;) {
284 			res = dbm_page_next();
285 			if (res.page == -1)
286 				break;
287 			slot = ohash_lookup_memory(htab,
288 			    (char *)&res, sizeof(res.page), res.page);
289 			if ((rp = ohash_find(htab, slot)) != NULL) {
290 				rp->bits |= res.bits;
291 				continue;
292 			}
293 			rp = mandoc_malloc(sizeof(*rp));
294 			*rp = res;
295 			ohash_insert(htab, slot, rp);
296 		}
297 	}
298 	return htab;
299 }
300 
301 static struct ohash *
302 manmerge_or(struct expr *e, struct ohash *htab)
303 {
304 	while (e != NULL) {
305 		htab = manmerge(e, htab);
306 		e = e->next;
307 	}
308 	return htab;
309 }
310 
311 static struct ohash *
312 manmerge_and(struct expr *e, struct ohash *htab)
313 {
314 	struct ohash	*hand, *h1, *h2;
315 	struct dbm_res	*res;
316 	unsigned int	 slot1, slot2;
317 
318 	/* Evaluate the first term of the AND clause. */
319 
320 	hand = manmerge(e, NULL);
321 
322 	while ((e = e->next) != NULL) {
323 
324 		/* Evaluate the next term and prepare for ANDing. */
325 
326 		h2 = manmerge(e, NULL);
327 		if (ohash_entries(h2) < ohash_entries(hand)) {
328 			h1 = h2;
329 			h2 = hand;
330 		} else
331 			h1 = hand;
332 		hand = mandoc_malloc(sizeof(*hand));
333 		mandoc_ohash_init(hand, 4, offsetof(struct dbm_res, page));
334 
335 		/* Keep all pages that are in both result sets. */
336 
337 		for (res = ohash_first(h1, &slot1); res != NULL;
338 		    res = ohash_next(h1, &slot1)) {
339 			if (ohash_find(h2, ohash_lookup_memory(h2,
340 			    (char *)res, sizeof(res->page),
341 			    res->page)) == NULL)
342 				free(res);
343 			else
344 				ohash_insert(hand, ohash_lookup_memory(hand,
345 				    (char *)res, sizeof(res->page),
346 				    res->page), res);
347 		}
348 
349 		/* Discard the merged results. */
350 
351 		for (res = ohash_first(h2, &slot2); res != NULL;
352 		    res = ohash_next(h2, &slot2))
353 			free(res);
354 		ohash_delete(h2);
355 		free(h2);
356 		ohash_delete(h1);
357 		free(h1);
358 	}
359 
360 	/* Merge the result of the AND into htab. */
361 
362 	if (htab == NULL)
363 		return hand;
364 
365 	for (res = ohash_first(hand, &slot1); res != NULL;
366 	    res = ohash_next(hand, &slot1)) {
367 		slot2 = ohash_lookup_memory(htab,
368 		    (char *)res, sizeof(res->page), res->page);
369 		if (ohash_find(htab, slot2) == NULL)
370 			ohash_insert(htab, slot2, res);
371 		else
372 			free(res);
373 	}
374 
375 	/* Discard the merged result. */
376 
377 	ohash_delete(hand);
378 	free(hand);
379 	return htab;
380 }
381 
382 void
383 mansearch_free(struct manpage *res, size_t sz)
384 {
385 	size_t	 i;
386 
387 	for (i = 0; i < sz; i++) {
388 		free(res[i].file);
389 		free(res[i].names);
390 		free(res[i].output);
391 	}
392 	free(res);
393 }
394 
395 static int
396 manpage_compare(const void *vp1, const void *vp2)
397 {
398 	const struct manpage	*mp1, *mp2;
399 	const char		*cp1, *cp2;
400 	size_t			 sz1, sz2;
401 	int			 diff;
402 
403 	mp1 = vp1;
404 	mp2 = vp2;
405 	if ((diff = mp2->bits - mp1->bits) ||
406 	    (diff = mp1->sec - mp2->sec))
407 		return diff;
408 
409 	/* Fall back to alphabetic ordering of names. */
410 	sz1 = strcspn(mp1->names, "(");
411 	sz2 = strcspn(mp2->names, "(");
412 	if (sz1 < sz2)
413 		sz1 = sz2;
414 	if ((diff = strncasecmp(mp1->names, mp2->names, sz1)))
415 		return diff;
416 
417 	/* For identical names and sections, prefer arch-dependent. */
418 	cp1 = strchr(mp1->names + sz1, '/');
419 	cp2 = strchr(mp2->names + sz2, '/');
420 	return cp1 != NULL && cp2 != NULL ? strcasecmp(cp1, cp2) :
421 	    cp1 != NULL ? -1 : cp2 != NULL ? 1 : 0;
422 }
423 
424 static char *
425 buildnames(const struct dbm_page *page)
426 {
427 	char	*buf;
428 	size_t	 i, sz;
429 
430 	sz = lstlen(page->name, 2) + 1 + lstlen(page->sect, 2) +
431 	    (page->arch == NULL ? 0 : 1 + lstlen(page->arch, 2)) + 2;
432 	buf = mandoc_malloc(sz);
433 	i = 0;
434 	lstcat(buf, &i, page->name, ", ");
435 	buf[i++] = '(';
436 	lstcat(buf, &i, page->sect, ", ");
437 	if (page->arch != NULL) {
438 		buf[i++] = '/';
439 		lstcat(buf, &i, page->arch, ", ");
440 	}
441 	buf[i++] = ')';
442 	buf[i++] = '\0';
443 	assert(i == sz);
444 	return buf;
445 }
446 
447 /*
448  * Count the buffer space needed to print the NUL-terminated
449  * list of NUL-terminated strings, when printing sep separator
450  * characters between strings.
451  */
452 static size_t
453 lstlen(const char *cp, size_t sep)
454 {
455 	size_t	 sz;
456 
457 	for (sz = 0; *cp != '\0'; cp++) {
458 
459 		/* Skip names appearing only in the SYNOPSIS. */
460 		if (*cp <= (char)(NAME_SYN & NAME_MASK)) {
461 			while (*cp != '\0')
462 				cp++;
463 			continue;
464 		}
465 
466 		/* Skip name class markers. */
467 		if (*cp < ' ')
468 			cp++;
469 
470 		/* Print a separator before each but the first string. */
471 		if (sz)
472 			sz += sep;
473 
474 		/* Copy one string. */
475 		while (*cp != '\0') {
476 			sz++;
477 			cp++;
478 		}
479 	}
480 	return sz;
481 }
482 
483 /*
484  * Print the NUL-terminated list of NUL-terminated strings
485  * into the buffer, seperating strings with sep.
486  */
487 static void
488 lstcat(char *buf, size_t *i, const char *cp, const char *sep)
489 {
490 	const char	*s;
491 	size_t		 i_start;
492 
493 	for (i_start = *i; *cp != '\0'; cp++) {
494 
495 		/* Skip names appearing only in the SYNOPSIS. */
496 		if (*cp <= (char)(NAME_SYN & NAME_MASK)) {
497 			while (*cp != '\0')
498 				cp++;
499 			continue;
500 		}
501 
502 		/* Skip name class markers. */
503 		if (*cp < ' ')
504 			cp++;
505 
506 		/* Print a separator before each but the first string. */
507 		if (*i > i_start) {
508 			s = sep;
509 			while (*s != '\0')
510 				buf[(*i)++] = *s++;
511 		}
512 
513 		/* Copy one string. */
514 		while (*cp != '\0')
515 			buf[(*i)++] = *cp++;
516 	}
517 
518 }
519 
520 /*
521  * Return 1 if the string *want occurs in any of the strings
522  * in the NUL-terminated string list *have, or 0 otherwise.
523  * If either argument is NULL or empty, assume no filtering
524  * is desired and return 1.
525  */
526 static int
527 lstmatch(const char *want, const char *have)
528 {
529         if (want == NULL || have == NULL || *have == '\0')
530                 return 1;
531         while (*have != '\0') {
532                 if (strcasestr(have, want) != NULL)
533                         return 1;
534                 have = strchr(have, '\0') + 1;
535         }
536         return 0;
537 }
538 
539 /*
540  * Build a list of values taken by the macro im in the manual page.
541  */
542 static char *
543 buildoutput(size_t im, struct dbm_page *page)
544 {
545 	const char	*oldoutput, *sep, *input;
546 	char		*output, *newoutput, *value;
547 	size_t		 sz, i;
548 
549 	switch (im) {
550 	case KEY_Nd:
551 		return mandoc_strdup(page->desc);
552 	case KEY_Nm:
553 		input = page->name;
554 		break;
555 	case KEY_sec:
556 		input = page->sect;
557 		break;
558 	case KEY_arch:
559 		input = page->arch;
560 		if (input == NULL)
561 			input = "all\0";
562 		break;
563 	default:
564 		input = NULL;
565 		break;
566 	}
567 
568 	if (input != NULL) {
569 		sz = lstlen(input, 3) + 1;
570 		output = mandoc_malloc(sz);
571 		i = 0;
572 		lstcat(output, &i, input, " # ");
573 		output[i++] = '\0';
574 		assert(i == sz);
575 		return output;
576 	}
577 
578 	output = NULL;
579 	dbm_macro_bypage(im - 2, page->addr);
580 	while ((value = dbm_macro_next()) != NULL) {
581 		if (output == NULL) {
582 			oldoutput = "";
583 			sep = "";
584 		} else {
585 			oldoutput = output;
586 			sep = " # ";
587 		}
588 		mandoc_asprintf(&newoutput, "%s%s%s", oldoutput, sep, value);
589 		free(output);
590 		output = newoutput;
591 	}
592 	return output;
593 }
594 
595 /*
596  * Compile a set of string tokens into an expression.
597  * Tokens in "argv" are assumed to be individual expression atoms (e.g.,
598  * "(", "foo=bar", etc.).
599  */
600 static struct expr *
601 exprcomp(const struct mansearch *search, int argc, char *argv[], int *argi)
602 {
603 	struct expr	*parent, *child;
604 	int		 needterm, nested;
605 
606 	if ((nested = *argi) == argc)
607 		return NULL;
608 	needterm = 1;
609 	parent = child = NULL;
610 	while (*argi < argc) {
611 		if (strcmp(")", argv[*argi]) == 0) {
612 			if (needterm)
613 				warnx("missing term "
614 				    "before closing parenthesis");
615 			needterm = 0;
616 			if (nested)
617 				break;
618 			warnx("ignoring unmatched right parenthesis");
619 			++*argi;
620 			continue;
621 		}
622 		if (strcmp("-o", argv[*argi]) == 0) {
623 			if (needterm) {
624 				if (*argi > 0)
625 					warnx("ignoring -o after %s",
626 					    argv[*argi - 1]);
627 				else
628 					warnx("ignoring initial -o");
629 			}
630 			needterm = 1;
631 			++*argi;
632 			continue;
633 		}
634 		needterm = 0;
635 		if (child == NULL) {
636 			child = expr_and(search, argc, argv, argi);
637 			continue;
638 		}
639 		if (parent == NULL) {
640 			parent = mandoc_calloc(1, sizeof(*parent));
641 			parent->type = EXPR_OR;
642 			parent->next = NULL;
643 			parent->child = child;
644 		}
645 		child->next = expr_and(search, argc, argv, argi);
646 		child = child->next;
647 	}
648 	if (needterm && *argi)
649 		warnx("ignoring trailing %s", argv[*argi - 1]);
650 	return parent == NULL ? child : parent;
651 }
652 
653 static struct expr *
654 expr_and(const struct mansearch *search, int argc, char *argv[], int *argi)
655 {
656 	struct expr	*parent, *child;
657 	int		 needterm;
658 
659 	needterm = 1;
660 	parent = child = NULL;
661 	while (*argi < argc) {
662 		if (strcmp(")", argv[*argi]) == 0) {
663 			if (needterm)
664 				warnx("missing term "
665 				    "before closing parenthesis");
666 			needterm = 0;
667 			break;
668 		}
669 		if (strcmp("-o", argv[*argi]) == 0)
670 			break;
671 		if (strcmp("-a", argv[*argi]) == 0) {
672 			if (needterm) {
673 				if (*argi > 0)
674 					warnx("ignoring -a after %s",
675 					    argv[*argi - 1]);
676 				else
677 					warnx("ignoring initial -a");
678 			}
679 			needterm = 1;
680 			++*argi;
681 			continue;
682 		}
683 		if (needterm == 0)
684 			break;
685 		if (child == NULL) {
686 			child = exprterm(search, argc, argv, argi);
687 			if (child != NULL)
688 				needterm = 0;
689 			continue;
690 		}
691 		needterm = 0;
692 		if (parent == NULL) {
693 			parent = mandoc_calloc(1, sizeof(*parent));
694 			parent->type = EXPR_AND;
695 			parent->next = NULL;
696 			parent->child = child;
697 		}
698 		child->next = exprterm(search, argc, argv, argi);
699 		if (child->next != NULL) {
700 			child = child->next;
701 			needterm = 0;
702 		}
703 	}
704 	if (needterm && *argi)
705 		warnx("ignoring trailing %s", argv[*argi - 1]);
706 	return parent == NULL ? child : parent;
707 }
708 
709 static struct expr *
710 exprterm(const struct mansearch *search, int argc, char *argv[], int *argi)
711 {
712 	char		 errbuf[BUFSIZ];
713 	struct expr	*e;
714 	char		*key, *val;
715 	uint64_t	 iterbit;
716 	int		 cs, i, irc;
717 
718 	if (strcmp("(", argv[*argi]) == 0) {
719 		++*argi;
720 		e = exprcomp(search, argc, argv, argi);
721 		if (*argi < argc) {
722 			assert(strcmp(")", argv[*argi]) == 0);
723 			++*argi;
724 		} else
725 			warnx("unclosed parenthesis");
726 		return e;
727 	}
728 
729 	if (strcmp("-i", argv[*argi]) == 0 && *argi + 1 < argc) {
730 		cs = 0;
731 		++*argi;
732 	} else
733 		cs = 1;
734 
735 	e = mandoc_calloc(1, sizeof(*e));
736 	e->type = EXPR_TERM;
737 	e->bits = 0;
738 	e->next = NULL;
739 	e->child = NULL;
740 
741 	if (search->argmode == ARG_NAME) {
742 		e->bits = TYPE_Nm;
743 		e->match.type = DBM_EXACT;
744 		e->match.str = argv[(*argi)++];
745 		return e;
746 	}
747 
748 	/*
749 	 * Separate macro keys from search string.
750 	 * If needed, request regular expression handling.
751 	 */
752 
753 	if (search->argmode == ARG_WORD) {
754 		e->bits = TYPE_Nm;
755 		e->match.type = DBM_REGEX;
756 #if HAVE_REWB_BSD
757 		mandoc_asprintf(&val, "[[:<:]]%s[[:>:]]", argv[*argi]);
758 #elif HAVE_REWB_SYSV
759 		mandoc_asprintf(&val, "\\<%s\\>", argv[*argi]);
760 #else
761 		mandoc_asprintf(&val,
762 		    "(^|[^a-zA-Z01-9_])%s([^a-zA-Z01-9_]|$)", argv[*argi]);
763 #endif
764 		cs = 0;
765 	} else if ((val = strpbrk(argv[*argi], "=~")) == NULL) {
766 		e->bits = TYPE_Nm | TYPE_Nd;
767 		e->match.type = DBM_SUB;
768 		e->match.str = argv[*argi];
769 	} else {
770 		if (val == argv[*argi])
771 			e->bits = TYPE_Nm | TYPE_Nd;
772 		if (*val == '=') {
773 			e->match.type = DBM_SUB;
774 			e->match.str = val + 1;
775 		} else
776 			e->match.type = DBM_REGEX;
777 		*val++ = '\0';
778 		if (strstr(argv[*argi], "arch") != NULL)
779 			cs = 0;
780 	}
781 
782 	/* Compile regular expressions. */
783 
784 	if (e->match.type == DBM_REGEX) {
785 		e->match.re = mandoc_malloc(sizeof(*e->match.re));
786 		irc = regcomp(e->match.re, val,
787 		    REG_EXTENDED | REG_NOSUB | (cs ? 0 : REG_ICASE));
788 		if (irc) {
789 			regerror(irc, e->match.re, errbuf, sizeof(errbuf));
790 			warnx("regcomp /%s/: %s", val, errbuf);
791 		}
792 		if (search->argmode == ARG_WORD)
793 			free(val);
794 		if (irc) {
795 			free(e->match.re);
796 			free(e);
797 			++*argi;
798 			return NULL;
799 		}
800 	}
801 
802 	if (e->bits) {
803 		++*argi;
804 		return e;
805 	}
806 
807 	/*
808 	 * Parse out all possible fields.
809 	 * If the field doesn't resolve, bail.
810 	 */
811 
812 	while (NULL != (key = strsep(&argv[*argi], ","))) {
813 		if ('\0' == *key)
814 			continue;
815 		for (i = 0, iterbit = 1; i < KEY_MAX; i++, iterbit <<= 1) {
816 			if (0 == strcasecmp(key, mansearch_keynames[i])) {
817 				e->bits |= iterbit;
818 				break;
819 			}
820 		}
821 		if (i == KEY_MAX) {
822 			if (strcasecmp(key, "any"))
823 				warnx("treating unknown key "
824 				    "\"%s\" as \"any\"", key);
825 			e->bits |= ~0ULL;
826 		}
827 	}
828 
829 	++*argi;
830 	return e;
831 }
832 
833 static void
834 exprfree(struct expr *e)
835 {
836 	if (e->next != NULL)
837 		exprfree(e->next);
838 	if (e->child != NULL)
839 		exprfree(e->child);
840 	free(e);
841 }
842