xref: /freebsd/contrib/mandoc/html.c (revision bc7512cc58af2e8bbe5bbf5ca0059b1daa1da897) 
1 /* $Id: html.c,v 1.275 2021/09/09 14:47:24 schwarze Exp $ */
2 /*
3  * Copyright (c) 2008-2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
4  * Copyright (c) 2011-2015, 2017-2021 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  * Common functions for mandoc(1) HTML formatters.
19  * For use by individual formatters and by the main program.
20  */
21 #include "config.h"
22 
23 #include <sys/types.h>
24 #include <sys/stat.h>
25 
26 #include <assert.h>
27 #include <ctype.h>
28 #include <stdarg.h>
29 #include <stddef.h>
30 #include <stdio.h>
31 #include <stdint.h>
32 #include <stdlib.h>
33 #include <string.h>
34 #include <unistd.h>
35 
36 #include "mandoc_aux.h"
37 #include "mandoc_ohash.h"
38 #include "mandoc.h"
39 #include "roff.h"
40 #include "out.h"
41 #include "html.h"
42 #include "manconf.h"
43 #include "main.h"
44 
45 struct	htmldata {
46 	const char	 *name;
47 	int		  flags;
48 #define	HTML_INPHRASE	 (1 << 0)  /* Can appear in phrasing context. */
49 #define	HTML_TOPHRASE	 (1 << 1)  /* Establishes phrasing context. */
50 #define	HTML_NOSTACK	 (1 << 2)  /* Does not have an end tag. */
51 #define	HTML_NLBEFORE	 (1 << 3)  /* Output line break before opening. */
52 #define	HTML_NLBEGIN	 (1 << 4)  /* Output line break after opening. */
53 #define	HTML_NLEND	 (1 << 5)  /* Output line break before closing. */
54 #define	HTML_NLAFTER	 (1 << 6)  /* Output line break after closing. */
55 #define	HTML_NLAROUND	 (HTML_NLBEFORE | HTML_NLAFTER)
56 #define	HTML_NLINSIDE	 (HTML_NLBEGIN | HTML_NLEND)
57 #define	HTML_NLALL	 (HTML_NLAROUND | HTML_NLINSIDE)
58 #define	HTML_INDENT	 (1 << 7)  /* Indent content by two spaces. */
59 #define	HTML_NOINDENT	 (1 << 8)  /* Exception: never indent content. */
60 };
61 
62 static	const struct htmldata htmltags[TAG_MAX] = {
63 	{"html",	HTML_NLALL},
64 	{"head",	HTML_NLALL | HTML_INDENT},
65 	{"meta",	HTML_NOSTACK | HTML_NLALL},
66 	{"link",	HTML_NOSTACK | HTML_NLALL},
67 	{"style",	HTML_NLALL | HTML_INDENT},
68 	{"title",	HTML_NLAROUND},
69 	{"body",	HTML_NLALL},
70 	{"div",		HTML_NLAROUND},
71 	{"section",	HTML_NLALL},
72 	{"table",	HTML_NLALL | HTML_INDENT},
73 	{"tr",		HTML_NLALL | HTML_INDENT},
74 	{"td",		HTML_NLAROUND},
75 	{"li",		HTML_NLAROUND | HTML_INDENT},
76 	{"ul",		HTML_NLALL | HTML_INDENT},
77 	{"ol",		HTML_NLALL | HTML_INDENT},
78 	{"dl",		HTML_NLALL | HTML_INDENT},
79 	{"dt",		HTML_NLAROUND},
80 	{"dd",		HTML_NLAROUND | HTML_INDENT},
81 	{"h1",		HTML_TOPHRASE | HTML_NLAROUND},
82 	{"h2",		HTML_TOPHRASE | HTML_NLAROUND},
83 	{"p",		HTML_TOPHRASE | HTML_NLAROUND | HTML_INDENT},
84 	{"pre",		HTML_TOPHRASE | HTML_NLAROUND | HTML_NOINDENT},
85 	{"a",		HTML_INPHRASE | HTML_TOPHRASE},
86 	{"b",		HTML_INPHRASE | HTML_TOPHRASE},
87 	{"cite",	HTML_INPHRASE | HTML_TOPHRASE},
88 	{"code",	HTML_INPHRASE | HTML_TOPHRASE},
89 	{"i",		HTML_INPHRASE | HTML_TOPHRASE},
90 	{"small",	HTML_INPHRASE | HTML_TOPHRASE},
91 	{"span",	HTML_INPHRASE | HTML_TOPHRASE},
92 	{"var",		HTML_INPHRASE | HTML_TOPHRASE},
93 	{"br",		HTML_INPHRASE | HTML_NOSTACK | HTML_NLALL},
94 	{"hr",		HTML_INPHRASE | HTML_NOSTACK},
95 	{"mark",	HTML_INPHRASE },
96 	{"math",	HTML_INPHRASE | HTML_NLALL | HTML_INDENT},
97 	{"mrow",	0},
98 	{"mi",		0},
99 	{"mn",		0},
100 	{"mo",		0},
101 	{"msup",	0},
102 	{"msub",	0},
103 	{"msubsup",	0},
104 	{"mfrac",	0},
105 	{"msqrt",	0},
106 	{"mfenced",	0},
107 	{"mtable",	0},
108 	{"mtr",		0},
109 	{"mtd",		0},
110 	{"munderover",	0},
111 	{"munder",	0},
112 	{"mover",	0},
113 };
114 
115 /* Avoid duplicate HTML id= attributes. */
116 
117 struct	id_entry {
118 	int	 ord;	/* Ordinal number of the latest occurrence. */
119 	char	 id[];	/* The id= attribute without any ordinal suffix. */
120 };
121 static	struct ohash	 id_unique;
122 
123 static	void	 html_reset_internal(struct html *);
124 static	void	 print_byte(struct html *, char);
125 static	void	 print_endword(struct html *);
126 static	void	 print_indent(struct html *);
127 static	void	 print_word(struct html *, const char *);
128 
129 static	void	 print_ctag(struct html *, struct tag *);
130 static	int	 print_escape(struct html *, char);
131 static	int	 print_encode(struct html *, const char *, const char *, int);
132 static	void	 print_href(struct html *, const char *, const char *, int);
133 static	void	 print_metaf(struct html *);
134 
135 
136 void *
137 html_alloc(const struct manoutput *outopts)
138 {
139 	struct html	*h;
140 
141 	h = mandoc_calloc(1, sizeof(struct html));
142 
143 	h->tag = NULL;
144 	h->metac = h->metal = ESCAPE_FONTROMAN;
145 	h->style = outopts->style;
146 	if ((h->base_man1 = outopts->man) == NULL)
147 		h->base_man2 = NULL;
148 	else if ((h->base_man2 = strchr(h->base_man1, ';')) != NULL)
149 		*h->base_man2++ = '\0';
150 	h->base_includes = outopts->includes;
151 	if (outopts->fragment)
152 		h->oflags |= HTML_FRAGMENT;
153 	if (outopts->toc)
154 		h->oflags |= HTML_TOC;
155 
156 	mandoc_ohash_init(&id_unique, 4, offsetof(struct id_entry, id));
157 
158 	return h;
159 }
160 
161 static void
162 html_reset_internal(struct html *h)
163 {
164 	struct tag	*tag;
165 	struct id_entry	*entry;
166 	unsigned int	 slot;
167 
168 	while ((tag = h->tag) != NULL) {
169 		h->tag = tag->next;
170 		free(tag);
171 	}
172 	entry = ohash_first(&id_unique, &slot);
173 	while (entry != NULL) {
174 		free(entry);
175 		entry = ohash_next(&id_unique, &slot);
176 	}
177 	ohash_delete(&id_unique);
178 }
179 
180 void
181 html_reset(void *p)
182 {
183 	html_reset_internal(p);
184 	mandoc_ohash_init(&id_unique, 4, offsetof(struct id_entry, id));
185 }
186 
187 void
188 html_free(void *p)
189 {
190 	html_reset_internal(p);
191 	free(p);
192 }
193 
194 void
195 print_gen_head(struct html *h)
196 {
197 	struct tag	*t;
198 
199 	print_otag(h, TAG_META, "?", "charset", "utf-8");
200 	print_otag(h, TAG_META, "??", "name", "viewport",
201 	    "content", "width=device-width, initial-scale=1.0");
202 	if (h->style != NULL) {
203 		print_otag(h, TAG_LINK, "?h??", "rel", "stylesheet",
204 		    h->style, "type", "text/css", "media", "all");
205 		return;
206 	}
207 
208 	/*
209 	 * Print a minimal embedded style sheet.
210 	 */
211 
212 	t = print_otag(h, TAG_STYLE, "");
213 	print_text(h, "table.head, table.foot { width: 100%; }");
214 	print_endline(h);
215 	print_text(h, "td.head-rtitle, td.foot-os { text-align: right; }");
216 	print_endline(h);
217 	print_text(h, "td.head-vol { text-align: center; }");
218 	print_endline(h);
219 	print_text(h, ".Nd, .Bf, .Op { display: inline; }");
220 	print_endline(h);
221 	print_text(h, ".Pa, .Ad { font-style: italic; }");
222 	print_endline(h);
223 	print_text(h, ".Ms { font-weight: bold; }");
224 	print_endline(h);
225 	print_text(h, ".Bl-diag ");
226 	print_byte(h, '>');
227 	print_text(h, " dt { font-weight: bold; }");
228 	print_endline(h);
229 	print_text(h, "code.Nm, .Fl, .Cm, .Ic, code.In, .Fd, .Fn, .Cd "
230 	    "{ font-weight: bold; font-family: inherit; }");
231 	print_tagq(h, t);
232 }
233 
234 int
235 html_setfont(struct html *h, enum mandoc_esc font)
236 {
237 	switch (font) {
238 	case ESCAPE_FONTPREV:
239 		font = h->metal;
240 		break;
241 	case ESCAPE_FONTITALIC:
242 	case ESCAPE_FONTBOLD:
243 	case ESCAPE_FONTBI:
244 	case ESCAPE_FONTROMAN:
245 	case ESCAPE_FONTCR:
246 	case ESCAPE_FONTCB:
247 	case ESCAPE_FONTCI:
248 		break;
249 	case ESCAPE_FONT:
250 		font = ESCAPE_FONTROMAN;
251 		break;
252 	default:
253 		return 0;
254 	}
255 	h->metal = h->metac;
256 	h->metac = font;
257 	return 1;
258 }
259 
260 static void
261 print_metaf(struct html *h)
262 {
263 	if (h->metaf) {
264 		print_tagq(h, h->metaf);
265 		h->metaf = NULL;
266 	}
267 	switch (h->metac) {
268 	case ESCAPE_FONTITALIC:
269 		h->metaf = print_otag(h, TAG_I, "");
270 		break;
271 	case ESCAPE_FONTBOLD:
272 		h->metaf = print_otag(h, TAG_B, "");
273 		break;
274 	case ESCAPE_FONTBI:
275 		h->metaf = print_otag(h, TAG_B, "");
276 		print_otag(h, TAG_I, "");
277 		break;
278 	case ESCAPE_FONTCR:
279 		h->metaf = print_otag(h, TAG_SPAN, "c", "Li");
280 		break;
281 	case ESCAPE_FONTCB:
282 		h->metaf = print_otag(h, TAG_SPAN, "c", "Li");
283 		print_otag(h, TAG_B, "");
284 		break;
285 	case ESCAPE_FONTCI:
286 		h->metaf = print_otag(h, TAG_SPAN, "c", "Li");
287 		print_otag(h, TAG_I, "");
288 		break;
289 	default:
290 		break;
291 	}
292 }
293 
294 void
295 html_close_paragraph(struct html *h)
296 {
297 	struct tag	*this, *next;
298 	int		 flags;
299 
300 	this = h->tag;
301 	for (;;) {
302 		next = this->next;
303 		flags = htmltags[this->tag].flags;
304 		if (flags & (HTML_INPHRASE | HTML_TOPHRASE))
305 			print_ctag(h, this);
306 		if ((flags & HTML_INPHRASE) == 0)
307 			break;
308 		this = next;
309 	}
310 }
311 
312 /*
313  * ROFF_nf switches to no-fill mode, ROFF_fi to fill mode.
314  * TOKEN_NONE does not switch.  The old mode is returned.
315  */
316 enum roff_tok
317 html_fillmode(struct html *h, enum roff_tok want)
318 {
319 	struct tag	*t;
320 	enum roff_tok	 had;
321 
322 	for (t = h->tag; t != NULL; t = t->next)
323 		if (t->tag == TAG_PRE)
324 			break;
325 
326 	had = t == NULL ? ROFF_fi : ROFF_nf;
327 
328 	if (want != had) {
329 		switch (want) {
330 		case ROFF_fi:
331 			print_tagq(h, t);
332 			break;
333 		case ROFF_nf:
334 			html_close_paragraph(h);
335 			print_otag(h, TAG_PRE, "");
336 			break;
337 		case TOKEN_NONE:
338 			break;
339 		default:
340 			abort();
341 		}
342 	}
343 	return had;
344 }
345 
346 /*
347  * Allocate a string to be used for the "id=" attribute of an HTML
348  * element and/or as a segment identifier for a URI in an <a> element.
349  * The function may fail and return NULL if the node lacks text data
350  * to create the attribute from.
351  * The caller is responsible for free(3)ing the returned string.
352  *
353  * If the "unique" argument is non-zero, the "id_unique" ohash table
354  * is used for de-duplication.  If the "unique" argument is 1,
355  * it is the first time the function is called for this tag and
356  * location, so if an ordinal suffix is needed, it is incremented.
357  * If the "unique" argument is 2, it is the second time the function
358  * is called for this tag and location, so the ordinal suffix
359  * remains unchanged.
360  */
361 char *
362 html_make_id(const struct roff_node *n, int unique)
363 {
364 	const struct roff_node	*nch;
365 	struct id_entry		*entry;
366 	char			*buf, *cp;
367 	size_t			 len;
368 	unsigned int		 slot;
369 
370 	if (n->tag != NULL)
371 		buf = mandoc_strdup(n->tag);
372 	else {
373 		switch (n->tok) {
374 		case MDOC_Sh:
375 		case MDOC_Ss:
376 		case MDOC_Sx:
377 		case MAN_SH:
378 		case MAN_SS:
379 			for (nch = n->child; nch != NULL; nch = nch->next)
380 				if (nch->type != ROFFT_TEXT)
381 					return NULL;
382 			buf = NULL;
383 			deroff(&buf, n);
384 			if (buf == NULL)
385 				return NULL;
386 			break;
387 		default:
388 			if (n->child == NULL || n->child->type != ROFFT_TEXT)
389 				return NULL;
390 			buf = mandoc_strdup(n->child->string);
391 			break;
392 		}
393 	}
394 
395 	/*
396 	 * In ID attributes, only use ASCII characters that are
397 	 * permitted in URL-fragment strings according to the
398 	 * explicit list at:
399 	 * https://url.spec.whatwg.org/#url-fragment-string
400 	 * In addition, reserve '~' for ordinal suffixes.
401 	 */
402 
403 	for (cp = buf; *cp != '\0'; cp++)
404 		if (isalnum((unsigned char)*cp) == 0 &&
405 		    strchr("!$&'()*+,-./:;=?@_", *cp) == NULL)
406 			*cp = '_';
407 
408 	if (unique == 0)
409 		return buf;
410 
411 	/* Avoid duplicate HTML id= attributes. */
412 
413 	slot = ohash_qlookup(&id_unique, buf);
414 	if ((entry = ohash_find(&id_unique, slot)) == NULL) {
415 		len = strlen(buf) + 1;
416 		entry = mandoc_malloc(sizeof(*entry) + len);
417 		entry->ord = 1;
418 		memcpy(entry->id, buf, len);
419 		ohash_insert(&id_unique, slot, entry);
420 	} else if (unique == 1)
421 		entry->ord++;
422 
423 	if (entry->ord > 1) {
424 		cp = buf;
425 		mandoc_asprintf(&buf, "%s~%d", cp, entry->ord);
426 		free(cp);
427 	}
428 	return buf;
429 }
430 
431 static int
432 print_escape(struct html *h, char c)
433 {
434 
435 	switch (c) {
436 	case '<':
437 		print_word(h, "&lt;");
438 		break;
439 	case '>':
440 		print_word(h, "&gt;");
441 		break;
442 	case '&':
443 		print_word(h, "&amp;");
444 		break;
445 	case '"':
446 		print_word(h, "&quot;");
447 		break;
448 	case ASCII_NBRSP:
449 		print_word(h, "&nbsp;");
450 		break;
451 	case ASCII_HYPH:
452 		print_byte(h, '-');
453 		break;
454 	case ASCII_BREAK:
455 		break;
456 	default:
457 		return 0;
458 	}
459 	return 1;
460 }
461 
462 static int
463 print_encode(struct html *h, const char *p, const char *pend, int norecurse)
464 {
465 	char		 numbuf[16];
466 	const char	*seq;
467 	size_t		 sz;
468 	int		 c, len, breakline, nospace;
469 	enum mandoc_esc	 esc;
470 	static const char rejs[10] = { ' ', '\\', '<', '>', '&', '"',
471 		ASCII_NBRSP, ASCII_HYPH, ASCII_BREAK, '\0' };
472 
473 	if (pend == NULL)
474 		pend = strchr(p, '\0');
475 
476 	breakline = 0;
477 	nospace = 0;
478 
479 	while (p < pend) {
480 		if (HTML_SKIPCHAR & h->flags && '\\' != *p) {
481 			h->flags &= ~HTML_SKIPCHAR;
482 			p++;
483 			continue;
484 		}
485 
486 		for (sz = strcspn(p, rejs); sz-- && p < pend; p++)
487 			print_byte(h, *p);
488 
489 		if (breakline &&
490 		    (p >= pend || *p == ' ' || *p == ASCII_NBRSP)) {
491 			print_otag(h, TAG_BR, "");
492 			breakline = 0;
493 			while (p < pend && (*p == ' ' || *p == ASCII_NBRSP))
494 				p++;
495 			continue;
496 		}
497 
498 		if (p >= pend)
499 			break;
500 
501 		if (*p == ' ') {
502 			print_endword(h);
503 			p++;
504 			continue;
505 		}
506 
507 		if (print_escape(h, *p++))
508 			continue;
509 
510 		esc = mandoc_escape(&p, &seq, &len);
511 		switch (esc) {
512 		case ESCAPE_FONT:
513 		case ESCAPE_FONTPREV:
514 		case ESCAPE_FONTBOLD:
515 		case ESCAPE_FONTITALIC:
516 		case ESCAPE_FONTBI:
517 		case ESCAPE_FONTROMAN:
518 		case ESCAPE_FONTCR:
519 		case ESCAPE_FONTCB:
520 		case ESCAPE_FONTCI:
521 			if (0 == norecurse) {
522 				h->flags |= HTML_NOSPACE;
523 				if (html_setfont(h, esc))
524 					print_metaf(h);
525 				h->flags &= ~HTML_NOSPACE;
526 			}
527 			continue;
528 		case ESCAPE_SKIPCHAR:
529 			h->flags |= HTML_SKIPCHAR;
530 			continue;
531 		case ESCAPE_ERROR:
532 			continue;
533 		default:
534 			break;
535 		}
536 
537 		if (h->flags & HTML_SKIPCHAR) {
538 			h->flags &= ~HTML_SKIPCHAR;
539 			continue;
540 		}
541 
542 		switch (esc) {
543 		case ESCAPE_UNICODE:
544 			/* Skip past "u" header. */
545 			c = mchars_num2uc(seq + 1, len - 1);
546 			break;
547 		case ESCAPE_NUMBERED:
548 			c = mchars_num2char(seq, len);
549 			if (c < 0)
550 				continue;
551 			break;
552 		case ESCAPE_SPECIAL:
553 			c = mchars_spec2cp(seq, len);
554 			if (c <= 0)
555 				continue;
556 			break;
557 		case ESCAPE_UNDEF:
558 			c = *seq;
559 			break;
560 		case ESCAPE_DEVICE:
561 			print_word(h, "html");
562 			continue;
563 		case ESCAPE_BREAK:
564 			breakline = 1;
565 			continue;
566 		case ESCAPE_NOSPACE:
567 			if ('\0' == *p)
568 				nospace = 1;
569 			continue;
570 		case ESCAPE_OVERSTRIKE:
571 			if (len == 0)
572 				continue;
573 			c = seq[len - 1];
574 			break;
575 		default:
576 			continue;
577 		}
578 		if ((c < 0x20 && c != 0x09) ||
579 		    (c > 0x7E && c < 0xA0))
580 			c = 0xFFFD;
581 		if (c > 0x7E) {
582 			(void)snprintf(numbuf, sizeof(numbuf), "&#x%.4X;", c);
583 			print_word(h, numbuf);
584 		} else if (print_escape(h, c) == 0)
585 			print_byte(h, c);
586 	}
587 
588 	return nospace;
589 }
590 
591 static void
592 print_href(struct html *h, const char *name, const char *sec, int man)
593 {
594 	struct stat	 sb;
595 	const char	*p, *pp;
596 	char		*filename;
597 
598 	if (man) {
599 		pp = h->base_man1;
600 		if (h->base_man2 != NULL) {
601 			mandoc_asprintf(&filename, "%s.%s", name, sec);
602 			if (stat(filename, &sb) == -1)
603 				pp = h->base_man2;
604 			free(filename);
605 		}
606 	} else
607 		pp = h->base_includes;
608 
609 	while ((p = strchr(pp, '%')) != NULL) {
610 		print_encode(h, pp, p, 1);
611 		if (man && p[1] == 'S') {
612 			if (sec == NULL)
613 				print_byte(h, '1');
614 			else
615 				print_encode(h, sec, NULL, 1);
616 		} else if ((man && p[1] == 'N') ||
617 		    (man == 0 && p[1] == 'I'))
618 			print_encode(h, name, NULL, 1);
619 		else
620 			print_encode(h, p, p + 2, 1);
621 		pp = p + 2;
622 	}
623 	if (*pp != '\0')
624 		print_encode(h, pp, NULL, 1);
625 }
626 
627 struct tag *
628 print_otag(struct html *h, enum htmltag tag, const char *fmt, ...)
629 {
630 	va_list		 ap;
631 	struct tag	*t;
632 	const char	*attr;
633 	char		*arg1, *arg2;
634 	int		 style_written, tflags;
635 
636 	tflags = htmltags[tag].flags;
637 
638 	/* Flow content is not allowed in phrasing context. */
639 
640 	if ((tflags & HTML_INPHRASE) == 0) {
641 		for (t = h->tag; t != NULL; t = t->next) {
642 			if (t->closed)
643 				continue;
644 			assert((htmltags[t->tag].flags & HTML_TOPHRASE) == 0);
645 			break;
646 		}
647 
648 	/*
649 	 * Always wrap phrasing elements in a paragraph
650 	 * unless already contained in some flow container;
651 	 * never put them directly into a section.
652 	 */
653 
654 	} else if (tflags & HTML_TOPHRASE && h->tag->tag == TAG_SECTION)
655 		print_otag(h, TAG_P, "c", "Pp");
656 
657 	/* Push this tag onto the stack of open scopes. */
658 
659 	if ((tflags & HTML_NOSTACK) == 0) {
660 		t = mandoc_malloc(sizeof(struct tag));
661 		t->tag = tag;
662 		t->next = h->tag;
663 		t->refcnt = 0;
664 		t->closed = 0;
665 		h->tag = t;
666 	} else
667 		t = NULL;
668 
669 	if (tflags & HTML_NLBEFORE)
670 		print_endline(h);
671 	if (h->col == 0)
672 		print_indent(h);
673 	else if ((h->flags & HTML_NOSPACE) == 0) {
674 		if (h->flags & HTML_KEEP)
675 			print_word(h, "&#x00A0;");
676 		else {
677 			if (h->flags & HTML_PREKEEP)
678 				h->flags |= HTML_KEEP;
679 			print_endword(h);
680 		}
681 	}
682 
683 	if ( ! (h->flags & HTML_NONOSPACE))
684 		h->flags &= ~HTML_NOSPACE;
685 	else
686 		h->flags |= HTML_NOSPACE;
687 
688 	/* Print out the tag name and attributes. */
689 
690 	print_byte(h, '<');
691 	print_word(h, htmltags[tag].name);
692 
693 	va_start(ap, fmt);
694 
695 	while (*fmt != '\0' && *fmt != 's') {
696 
697 		/* Parse attributes and arguments. */
698 
699 		arg1 = va_arg(ap, char *);
700 		arg2 = NULL;
701 		switch (*fmt++) {
702 		case 'c':
703 			attr = "class";
704 			break;
705 		case 'h':
706 			attr = "href";
707 			break;
708 		case 'i':
709 			attr = "id";
710 			break;
711 		case '?':
712 			attr = arg1;
713 			arg1 = va_arg(ap, char *);
714 			break;
715 		default:
716 			abort();
717 		}
718 		if (*fmt == 'M')
719 			arg2 = va_arg(ap, char *);
720 		if (arg1 == NULL)
721 			continue;
722 
723 		/* Print the attributes. */
724 
725 		print_byte(h, ' ');
726 		print_word(h, attr);
727 		print_byte(h, '=');
728 		print_byte(h, '"');
729 		switch (*fmt) {
730 		case 'I':
731 			print_href(h, arg1, NULL, 0);
732 			fmt++;
733 			break;
734 		case 'M':
735 			print_href(h, arg1, arg2, 1);
736 			fmt++;
737 			break;
738 		case 'R':
739 			print_byte(h, '#');
740 			print_encode(h, arg1, NULL, 1);
741 			fmt++;
742 			break;
743 		default:
744 			print_encode(h, arg1, NULL, 1);
745 			break;
746 		}
747 		print_byte(h, '"');
748 	}
749 
750 	style_written = 0;
751 	while (*fmt++ == 's') {
752 		arg1 = va_arg(ap, char *);
753 		arg2 = va_arg(ap, char *);
754 		if (arg2 == NULL)
755 			continue;
756 		print_byte(h, ' ');
757 		if (style_written == 0) {
758 			print_word(h, "style=\"");
759 			style_written = 1;
760 		}
761 		print_word(h, arg1);
762 		print_byte(h, ':');
763 		print_byte(h, ' ');
764 		print_word(h, arg2);
765 		print_byte(h, ';');
766 	}
767 	if (style_written)
768 		print_byte(h, '"');
769 
770 	va_end(ap);
771 
772 	/* Accommodate for "well-formed" singleton escaping. */
773 
774 	if (htmltags[tag].flags & HTML_NOSTACK)
775 		print_byte(h, '/');
776 
777 	print_byte(h, '>');
778 
779 	if (tflags & HTML_NLBEGIN)
780 		print_endline(h);
781 	else
782 		h->flags |= HTML_NOSPACE;
783 
784 	if (tflags & HTML_INDENT)
785 		h->indent++;
786 	if (tflags & HTML_NOINDENT)
787 		h->noindent++;
788 
789 	return t;
790 }
791 
792 /*
793  * Print an element with an optional "id=" attribute.
794  * If the element has phrasing content and an "id=" attribute,
795  * also add a permalink: outside if it can be in phrasing context,
796  * inside otherwise.
797  */
798 struct tag *
799 print_otag_id(struct html *h, enum htmltag elemtype, const char *cattr,
800     struct roff_node *n)
801 {
802 	struct roff_node *nch;
803 	struct tag	*ret, *t;
804 	char		*id, *href;
805 
806 	ret = NULL;
807 	id = href = NULL;
808 	if (n->flags & NODE_ID)
809 		id = html_make_id(n, 1);
810 	if (n->flags & NODE_HREF)
811 		href = id == NULL ? html_make_id(n, 2) : id;
812 	if (href != NULL && htmltags[elemtype].flags & HTML_INPHRASE)
813 		ret = print_otag(h, TAG_A, "chR", "permalink", href);
814 	t = print_otag(h, elemtype, "ci", cattr, id);
815 	if (ret == NULL) {
816 		ret = t;
817 		if (href != NULL && (nch = n->child) != NULL) {
818 			/* man(7) is safe, it tags phrasing content only. */
819 			if (n->tok > MDOC_MAX ||
820 			    htmltags[elemtype].flags & HTML_TOPHRASE)
821 				nch = NULL;
822 			else  /* For mdoc(7), beware of nested blocks. */
823 				while (nch != NULL && nch->type == ROFFT_TEXT)
824 					nch = nch->next;
825 			if (nch == NULL)
826 				print_otag(h, TAG_A, "chR", "permalink", href);
827 		}
828 	}
829 	free(id);
830 	if (id == NULL)
831 		free(href);
832 	return ret;
833 }
834 
835 static void
836 print_ctag(struct html *h, struct tag *tag)
837 {
838 	int	 tflags;
839 
840 	if (tag->closed == 0) {
841 		tag->closed = 1;
842 		if (tag == h->metaf)
843 			h->metaf = NULL;
844 		if (tag == h->tblt)
845 			h->tblt = NULL;
846 
847 		tflags = htmltags[tag->tag].flags;
848 		if (tflags & HTML_INDENT)
849 			h->indent--;
850 		if (tflags & HTML_NOINDENT)
851 			h->noindent--;
852 		if (tflags & HTML_NLEND)
853 			print_endline(h);
854 		print_indent(h);
855 		print_byte(h, '<');
856 		print_byte(h, '/');
857 		print_word(h, htmltags[tag->tag].name);
858 		print_byte(h, '>');
859 		if (tflags & HTML_NLAFTER)
860 			print_endline(h);
861 	}
862 	if (tag->refcnt == 0) {
863 		h->tag = tag->next;
864 		free(tag);
865 	}
866 }
867 
868 void
869 print_gen_decls(struct html *h)
870 {
871 	print_word(h, "<!DOCTYPE html>");
872 	print_endline(h);
873 }
874 
875 void
876 print_gen_comment(struct html *h, struct roff_node *n)
877 {
878 	int	 wantblank;
879 
880 	print_word(h, "<!-- This is an automatically generated file."
881 	    "  Do not edit.");
882 	h->indent = 1;
883 	wantblank = 0;
884 	while (n != NULL && n->type == ROFFT_COMMENT) {
885 		if (strstr(n->string, "-->") == NULL &&
886 		    (wantblank || *n->string != '\0')) {
887 			print_endline(h);
888 			print_indent(h);
889 			print_word(h, n->string);
890 			wantblank = *n->string != '\0';
891 		}
892 		n = n->next;
893 	}
894 	if (wantblank)
895 		print_endline(h);
896 	print_word(h, " -->");
897 	print_endline(h);
898 	h->indent = 0;
899 }
900 
901 void
902 print_text(struct html *h, const char *word)
903 {
904 	print_tagged_text(h, word, NULL);
905 }
906 
907 void
908 print_tagged_text(struct html *h, const char *word, struct roff_node *n)
909 {
910 	struct tag	*t;
911 	char		*href;
912 
913 	/*
914 	 * Always wrap text in a paragraph unless already contained in
915 	 * some flow container; never put it directly into a section.
916 	 */
917 
918 	if (h->tag->tag == TAG_SECTION)
919 		print_otag(h, TAG_P, "c", "Pp");
920 
921 	/* Output whitespace before this text? */
922 
923 	if (h->col && (h->flags & HTML_NOSPACE) == 0) {
924 		if ( ! (HTML_KEEP & h->flags)) {
925 			if (HTML_PREKEEP & h->flags)
926 				h->flags |= HTML_KEEP;
927 			print_endword(h);
928 		} else
929 			print_word(h, "&#x00A0;");
930 	}
931 
932 	/*
933 	 * Optionally switch fonts, optionally write a permalink, then
934 	 * print the text, optionally surrounded by HTML whitespace.
935 	 */
936 
937 	assert(h->metaf == NULL);
938 	print_metaf(h);
939 	print_indent(h);
940 
941 	if (n != NULL && (href = html_make_id(n, 2)) != NULL) {
942 		t = print_otag(h, TAG_A, "chR", "permalink", href);
943 		free(href);
944 	} else
945 		t = NULL;
946 
947 	if ( ! print_encode(h, word, NULL, 0)) {
948 		if ( ! (h->flags & HTML_NONOSPACE))
949 			h->flags &= ~HTML_NOSPACE;
950 		h->flags &= ~HTML_NONEWLINE;
951 	} else
952 		h->flags |= HTML_NOSPACE | HTML_NONEWLINE;
953 
954 	if (h->metaf != NULL) {
955 		print_tagq(h, h->metaf);
956 		h->metaf = NULL;
957 	} else if (t != NULL)
958 		print_tagq(h, t);
959 
960 	h->flags &= ~HTML_IGNDELIM;
961 }
962 
963 void
964 print_tagq(struct html *h, const struct tag *until)
965 {
966 	struct tag	*this, *next;
967 
968 	for (this = h->tag; this != NULL; this = next) {
969 		next = this == until ? NULL : this->next;
970 		print_ctag(h, this);
971 	}
972 }
973 
974 /*
975  * Close out all open elements up to but excluding suntil.
976  * Note that a paragraph just inside stays open together with it
977  * because paragraphs include subsequent phrasing content.
978  */
979 void
980 print_stagq(struct html *h, const struct tag *suntil)
981 {
982 	struct tag	*this, *next;
983 
984 	for (this = h->tag; this != NULL; this = next) {
985 		next = this->next;
986 		if (this == suntil || (next == suntil &&
987 		    (this->tag == TAG_P || this->tag == TAG_PRE)))
988 			break;
989 		print_ctag(h, this);
990 	}
991 }
992 
993 
994 /***********************************************************************
995  * Low level output functions.
996  * They implement line breaking using a short static buffer.
997  ***********************************************************************/
998 
999 /*
1000  * Buffer one HTML output byte.
1001  * If the buffer is full, flush and deactivate it and start a new line.
1002  * If the buffer is inactive, print directly.
1003  */
1004 static void
1005 print_byte(struct html *h, char c)
1006 {
1007 	if ((h->flags & HTML_BUFFER) == 0) {
1008 		putchar(c);
1009 		h->col++;
1010 		return;
1011 	}
1012 
1013 	if (h->col + h->bufcol < sizeof(h->buf)) {
1014 		h->buf[h->bufcol++] = c;
1015 		return;
1016 	}
1017 
1018 	putchar('\n');
1019 	h->col = 0;
1020 	print_indent(h);
1021 	putchar(' ');
1022 	putchar(' ');
1023 	fwrite(h->buf, h->bufcol, 1, stdout);
1024 	putchar(c);
1025 	h->col = (h->indent + 1) * 2 + h->bufcol + 1;
1026 	h->bufcol = 0;
1027 	h->flags &= ~HTML_BUFFER;
1028 }
1029 
1030 /*
1031  * If something was printed on the current output line, end it.
1032  * Not to be called right after print_indent().
1033  */
1034 void
1035 print_endline(struct html *h)
1036 {
1037 	if (h->col == 0)
1038 		return;
1039 
1040 	if (h->bufcol) {
1041 		putchar(' ');
1042 		fwrite(h->buf, h->bufcol, 1, stdout);
1043 		h->bufcol = 0;
1044 	}
1045 	putchar('\n');
1046 	h->col = 0;
1047 	h->flags |= HTML_NOSPACE;
1048 	h->flags &= ~HTML_BUFFER;
1049 }
1050 
1051 /*
1052  * Flush the HTML output buffer.
1053  * If it is inactive, activate it.
1054  */
1055 static void
1056 print_endword(struct html *h)
1057 {
1058 	if (h->noindent) {
1059 		print_byte(h, ' ');
1060 		return;
1061 	}
1062 
1063 	if ((h->flags & HTML_BUFFER) == 0) {
1064 		h->col++;
1065 		h->flags |= HTML_BUFFER;
1066 	} else if (h->bufcol) {
1067 		putchar(' ');
1068 		fwrite(h->buf, h->bufcol, 1, stdout);
1069 		h->col += h->bufcol + 1;
1070 	}
1071 	h->bufcol = 0;
1072 }
1073 
1074 /*
1075  * If at the beginning of a new output line,
1076  * perform indentation and mark the line as containing output.
1077  * Make sure to really produce some output right afterwards,
1078  * but do not use print_otag() for producing it.
1079  */
1080 static void
1081 print_indent(struct html *h)
1082 {
1083 	size_t	 i;
1084 
1085 	if (h->col || h->noindent)
1086 		return;
1087 
1088 	h->col = h->indent * 2;
1089 	for (i = 0; i < h->col; i++)
1090 		putchar(' ');
1091 }
1092 
1093 /*
1094  * Print or buffer some characters
1095  * depending on the current HTML output buffer state.
1096  */
1097 static void
1098 print_word(struct html *h, const char *cp)
1099 {
1100 	while (*cp != '\0')
1101 		print_byte(h, *cp++);
1102 }
1103