xref: /openbsd-src/usr.bin/mandoc/html.c (revision d59bb9942320b767f2a19aaa7690c8c6e30b724c)
1 /*	$OpenBSD: html.c,v 1.77 2017/02/05 20:21:17 schwarze Exp $ */
2 /*
3  * Copyright (c) 2008-2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
4  * Copyright (c) 2011-2015, 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 <sys/types.h>
19 
20 #include <assert.h>
21 #include <ctype.h>
22 #include <stdarg.h>
23 #include <stdio.h>
24 #include <stdint.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <unistd.h>
28 
29 #include "mandoc.h"
30 #include "mandoc_aux.h"
31 #include "out.h"
32 #include "html.h"
33 #include "manconf.h"
34 #include "main.h"
35 
36 struct	htmldata {
37 	const char	 *name;
38 	int		  flags;
39 #define	HTML_NOSTACK	 (1 << 0)
40 #define	HTML_AUTOCLOSE	 (1 << 1)
41 #define	HTML_NLBEFORE	 (1 << 2)
42 #define	HTML_NLBEGIN	 (1 << 3)
43 #define	HTML_NLEND	 (1 << 4)
44 #define	HTML_NLAFTER	 (1 << 5)
45 #define	HTML_NLAROUND	 (HTML_NLBEFORE | HTML_NLAFTER)
46 #define	HTML_NLINSIDE	 (HTML_NLBEGIN | HTML_NLEND)
47 #define	HTML_NLALL	 (HTML_NLAROUND | HTML_NLINSIDE)
48 #define	HTML_INDENT	 (1 << 6)
49 #define	HTML_NOINDENT	 (1 << 7)
50 };
51 
52 static	const struct htmldata htmltags[TAG_MAX] = {
53 	{"html",	HTML_NLALL},
54 	{"head",	HTML_NLALL | HTML_INDENT},
55 	{"body",	HTML_NLALL},
56 	{"meta",	HTML_NOSTACK | HTML_AUTOCLOSE | HTML_NLALL},
57 	{"title",	HTML_NLAROUND},
58 	{"div",		HTML_NLAROUND},
59 	{"h1",		HTML_NLAROUND},
60 	{"h2",		HTML_NLAROUND},
61 	{"span",	0},
62 	{"link",	HTML_NOSTACK | HTML_AUTOCLOSE | HTML_NLALL},
63 	{"br",		HTML_NOSTACK | HTML_AUTOCLOSE | HTML_NLALL},
64 	{"a",		0},
65 	{"table",	HTML_NLALL | HTML_INDENT},
66 	{"colgroup",	HTML_NLALL | HTML_INDENT},
67 	{"col",		HTML_NOSTACK | HTML_AUTOCLOSE | HTML_NLALL},
68 	{"tr",		HTML_NLALL | HTML_INDENT},
69 	{"td",		HTML_NLAROUND},
70 	{"li",		HTML_NLAROUND | HTML_INDENT},
71 	{"ul",		HTML_NLALL | HTML_INDENT},
72 	{"ol",		HTML_NLALL | HTML_INDENT},
73 	{"dl",		HTML_NLALL | HTML_INDENT},
74 	{"dt",		HTML_NLAROUND},
75 	{"dd",		HTML_NLAROUND | HTML_INDENT},
76 	{"pre",		HTML_NLALL | HTML_NOINDENT},
77 	{"var",		0},
78 	{"cite",	0},
79 	{"b",		0},
80 	{"i",		0},
81 	{"code",	0},
82 	{"small",	0},
83 	{"style",	HTML_NLALL | HTML_INDENT},
84 	{"math",	HTML_NLALL | HTML_INDENT},
85 	{"mrow",	0},
86 	{"mi",		0},
87 	{"mo",		0},
88 	{"msup",	0},
89 	{"msub",	0},
90 	{"msubsup",	0},
91 	{"mfrac",	0},
92 	{"msqrt",	0},
93 	{"mfenced",	0},
94 	{"mtable",	0},
95 	{"mtr",		0},
96 	{"mtd",		0},
97 	{"munderover",	0},
98 	{"munder",	0},
99 	{"mover",	0},
100 };
101 
102 static	const char	*const roffscales[SCALE_MAX] = {
103 	"cm", /* SCALE_CM */
104 	"in", /* SCALE_IN */
105 	"pc", /* SCALE_PC */
106 	"pt", /* SCALE_PT */
107 	"em", /* SCALE_EM */
108 	"em", /* SCALE_MM */
109 	"ex", /* SCALE_EN */
110 	"ex", /* SCALE_BU */
111 	"em", /* SCALE_VS */
112 	"ex", /* SCALE_FS */
113 };
114 
115 static	void	 a2width(const char *, struct roffsu *);
116 static	void	 print_byte(struct html *, char);
117 static	void	 print_endword(struct html *);
118 static	void	 print_indent(struct html *);
119 static	void	 print_word(struct html *, const char *);
120 
121 static	void	 print_ctag(struct html *, struct tag *);
122 static	int	 print_escape(struct html *, char);
123 static	int	 print_encode(struct html *, const char *, const char *, int);
124 static	void	 print_href(struct html *, const char *, const char *, int);
125 static	void	 print_metaf(struct html *, enum mandoc_esc);
126 
127 
128 void *
129 html_alloc(const struct manoutput *outopts)
130 {
131 	struct html	*h;
132 
133 	h = mandoc_calloc(1, sizeof(struct html));
134 
135 	h->tag = NULL;
136 	h->style = outopts->style;
137 	h->base_man = outopts->man;
138 	h->base_includes = outopts->includes;
139 	if (outopts->fragment)
140 		h->oflags |= HTML_FRAGMENT;
141 
142 	return h;
143 }
144 
145 void
146 html_free(void *p)
147 {
148 	struct tag	*tag;
149 	struct html	*h;
150 
151 	h = (struct html *)p;
152 
153 	while ((tag = h->tag) != NULL) {
154 		h->tag = tag->next;
155 		free(tag);
156 	}
157 
158 	free(h);
159 }
160 
161 void
162 print_gen_head(struct html *h)
163 {
164 	struct tag	*t;
165 
166 	print_otag(h, TAG_META, "?", "charset", "utf-8");
167 
168 	/*
169 	 * Print a default style-sheet.
170 	 */
171 
172 	t = print_otag(h, TAG_STYLE, "");
173 	print_text(h, "table.head, table.foot { width: 100%; }");
174 	print_endline(h);
175 	print_text(h, "td.head-rtitle, td.foot-os { text-align: right; }");
176 	print_endline(h);
177 	print_text(h, "td.head-vol { text-align: center; }");
178 	print_endline(h);
179 	print_text(h, "div.Pp { margin: 1ex 0ex; }");
180 	print_tagq(h, t);
181 
182 	if (h->style)
183 		print_otag(h, TAG_LINK, "?h??", "rel", "stylesheet",
184 		    h->style, "type", "text/css", "media", "all");
185 }
186 
187 static void
188 print_metaf(struct html *h, enum mandoc_esc deco)
189 {
190 	enum htmlfont	 font;
191 
192 	switch (deco) {
193 	case ESCAPE_FONTPREV:
194 		font = h->metal;
195 		break;
196 	case ESCAPE_FONTITALIC:
197 		font = HTMLFONT_ITALIC;
198 		break;
199 	case ESCAPE_FONTBOLD:
200 		font = HTMLFONT_BOLD;
201 		break;
202 	case ESCAPE_FONTBI:
203 		font = HTMLFONT_BI;
204 		break;
205 	case ESCAPE_FONT:
206 	case ESCAPE_FONTROMAN:
207 		font = HTMLFONT_NONE;
208 		break;
209 	default:
210 		abort();
211 	}
212 
213 	if (h->metaf) {
214 		print_tagq(h, h->metaf);
215 		h->metaf = NULL;
216 	}
217 
218 	h->metal = h->metac;
219 	h->metac = font;
220 
221 	switch (font) {
222 	case HTMLFONT_ITALIC:
223 		h->metaf = print_otag(h, TAG_I, "");
224 		break;
225 	case HTMLFONT_BOLD:
226 		h->metaf = print_otag(h, TAG_B, "");
227 		break;
228 	case HTMLFONT_BI:
229 		h->metaf = print_otag(h, TAG_B, "");
230 		print_otag(h, TAG_I, "");
231 		break;
232 	default:
233 		break;
234 	}
235 }
236 
237 int
238 html_strlen(const char *cp)
239 {
240 	size_t		 rsz;
241 	int		 skip, sz;
242 
243 	/*
244 	 * Account for escaped sequences within string length
245 	 * calculations.  This follows the logic in term_strlen() as we
246 	 * must calculate the width of produced strings.
247 	 * Assume that characters are always width of "1".  This is
248 	 * hacky, but it gets the job done for approximation of widths.
249 	 */
250 
251 	sz = 0;
252 	skip = 0;
253 	while (1) {
254 		rsz = strcspn(cp, "\\");
255 		if (rsz) {
256 			cp += rsz;
257 			if (skip) {
258 				skip = 0;
259 				rsz--;
260 			}
261 			sz += rsz;
262 		}
263 		if ('\0' == *cp)
264 			break;
265 		cp++;
266 		switch (mandoc_escape(&cp, NULL, NULL)) {
267 		case ESCAPE_ERROR:
268 			return sz;
269 		case ESCAPE_UNICODE:
270 		case ESCAPE_NUMBERED:
271 		case ESCAPE_SPECIAL:
272 		case ESCAPE_OVERSTRIKE:
273 			if (skip)
274 				skip = 0;
275 			else
276 				sz++;
277 			break;
278 		case ESCAPE_SKIPCHAR:
279 			skip = 1;
280 			break;
281 		default:
282 			break;
283 		}
284 	}
285 	return sz;
286 }
287 
288 static int
289 print_escape(struct html *h, char c)
290 {
291 
292 	switch (c) {
293 	case '<':
294 		print_word(h, "&lt;");
295 		break;
296 	case '>':
297 		print_word(h, "&gt;");
298 		break;
299 	case '&':
300 		print_word(h, "&amp;");
301 		break;
302 	case '"':
303 		print_word(h, "&quot;");
304 		break;
305 	case ASCII_NBRSP:
306 		print_word(h, "&nbsp;");
307 		break;
308 	case ASCII_HYPH:
309 		print_byte(h, '-');
310 		break;
311 	case ASCII_BREAK:
312 		break;
313 	default:
314 		return 0;
315 	}
316 	return 1;
317 }
318 
319 static int
320 print_encode(struct html *h, const char *p, const char *pend, int norecurse)
321 {
322 	char		 numbuf[16];
323 	size_t		 sz;
324 	int		 c, len, nospace;
325 	const char	*seq;
326 	enum mandoc_esc	 esc;
327 	static const char rejs[9] = { '\\', '<', '>', '&', '"',
328 		ASCII_NBRSP, ASCII_HYPH, ASCII_BREAK, '\0' };
329 
330 	if (pend == NULL)
331 		pend = strchr(p, '\0');
332 
333 	nospace = 0;
334 
335 	while (p < pend) {
336 		if (HTML_SKIPCHAR & h->flags && '\\' != *p) {
337 			h->flags &= ~HTML_SKIPCHAR;
338 			p++;
339 			continue;
340 		}
341 
342 		for (sz = strcspn(p, rejs); sz-- && p < pend; p++)
343 			if (*p == ' ')
344 				print_endword(h);
345 			else
346 				print_byte(h, *p);
347 
348 		if (p >= pend)
349 			break;
350 
351 		if (print_escape(h, *p++))
352 			continue;
353 
354 		esc = mandoc_escape(&p, &seq, &len);
355 		if (ESCAPE_ERROR == esc)
356 			break;
357 
358 		switch (esc) {
359 		case ESCAPE_FONT:
360 		case ESCAPE_FONTPREV:
361 		case ESCAPE_FONTBOLD:
362 		case ESCAPE_FONTITALIC:
363 		case ESCAPE_FONTBI:
364 		case ESCAPE_FONTROMAN:
365 			if (0 == norecurse)
366 				print_metaf(h, esc);
367 			continue;
368 		case ESCAPE_SKIPCHAR:
369 			h->flags |= HTML_SKIPCHAR;
370 			continue;
371 		default:
372 			break;
373 		}
374 
375 		if (h->flags & HTML_SKIPCHAR) {
376 			h->flags &= ~HTML_SKIPCHAR;
377 			continue;
378 		}
379 
380 		switch (esc) {
381 		case ESCAPE_UNICODE:
382 			/* Skip past "u" header. */
383 			c = mchars_num2uc(seq + 1, len - 1);
384 			break;
385 		case ESCAPE_NUMBERED:
386 			c = mchars_num2char(seq, len);
387 			if (c < 0)
388 				continue;
389 			break;
390 		case ESCAPE_SPECIAL:
391 			c = mchars_spec2cp(seq, len);
392 			if (c <= 0)
393 				continue;
394 			break;
395 		case ESCAPE_NOSPACE:
396 			if ('\0' == *p)
397 				nospace = 1;
398 			continue;
399 		case ESCAPE_OVERSTRIKE:
400 			if (len == 0)
401 				continue;
402 			c = seq[len - 1];
403 			break;
404 		default:
405 			continue;
406 		}
407 		if ((c < 0x20 && c != 0x09) ||
408 		    (c > 0x7E && c < 0xA0))
409 			c = 0xFFFD;
410 		if (c > 0x7E) {
411 			(void)snprintf(numbuf, sizeof(numbuf), "&#%d;", c);
412 			print_word(h, numbuf);
413 		} else if (print_escape(h, c) == 0)
414 			print_byte(h, c);
415 	}
416 
417 	return nospace;
418 }
419 
420 static void
421 print_href(struct html *h, const char *name, const char *sec, int man)
422 {
423 	const char	*p, *pp;
424 
425 	pp = man ? h->base_man : h->base_includes;
426 	while ((p = strchr(pp, '%')) != NULL) {
427 		print_encode(h, pp, p, 1);
428 		if (man && p[1] == 'S') {
429 			if (sec == NULL)
430 				print_byte(h, '1');
431 			else
432 				print_encode(h, sec, NULL, 1);
433 		} else if ((man && p[1] == 'N') ||
434 		    (man == 0 && p[1] == 'I'))
435 			print_encode(h, name, NULL, 1);
436 		else
437 			print_encode(h, p, p + 2, 1);
438 		pp = p + 2;
439 	}
440 	if (*pp != '\0')
441 		print_encode(h, pp, NULL, 1);
442 }
443 
444 struct tag *
445 print_otag(struct html *h, enum htmltag tag, const char *fmt, ...)
446 {
447 	va_list		 ap;
448 	struct roffsu	 mysu, *su;
449 	char		 numbuf[16];
450 	struct tag	*t;
451 	const char	*attr;
452 	char		*arg1, *arg2;
453 	double		 v;
454 	int		 i, have_style, tflags;
455 
456 	tflags = htmltags[tag].flags;
457 
458 	/* Push this tag onto the stack of open scopes. */
459 
460 	if ((tflags & HTML_NOSTACK) == 0) {
461 		t = mandoc_malloc(sizeof(struct tag));
462 		t->tag = tag;
463 		t->next = h->tag;
464 		h->tag = t;
465 	} else
466 		t = NULL;
467 
468 	if (tflags & HTML_NLBEFORE)
469 		print_endline(h);
470 	if (h->col == 0)
471 		print_indent(h);
472 	else if ((h->flags & HTML_NOSPACE) == 0) {
473 		if (h->flags & HTML_KEEP)
474 			print_word(h, "&#160;");
475 		else {
476 			if (h->flags & HTML_PREKEEP)
477 				h->flags |= HTML_KEEP;
478 			print_endword(h);
479 		}
480 	}
481 
482 	if ( ! (h->flags & HTML_NONOSPACE))
483 		h->flags &= ~HTML_NOSPACE;
484 	else
485 		h->flags |= HTML_NOSPACE;
486 
487 	/* Print out the tag name and attributes. */
488 
489 	print_byte(h, '<');
490 	print_word(h, htmltags[tag].name);
491 
492 	va_start(ap, fmt);
493 
494 	have_style = 0;
495 	while (*fmt != '\0') {
496 		if (*fmt == 's') {
497 			have_style = 1;
498 			fmt++;
499 			break;
500 		}
501 
502 		/* Parse a non-style attribute and its arguments. */
503 
504 		arg1 = va_arg(ap, char *);
505 		switch (*fmt++) {
506 		case 'c':
507 			attr = "class";
508 			break;
509 		case 'h':
510 			attr = "href";
511 			break;
512 		case 'i':
513 			attr = "id";
514 			break;
515 		case '?':
516 			attr = arg1;
517 			arg1 = va_arg(ap, char *);
518 			break;
519 		default:
520 			abort();
521 		}
522 		arg2 = NULL;
523 		if (*fmt == 'M')
524 			arg2 = va_arg(ap, char *);
525 		if (arg1 == NULL)
526 			continue;
527 
528 		/* Print the non-style attributes. */
529 
530 		print_byte(h, ' ');
531 		print_word(h, attr);
532 		print_byte(h, '=');
533 		print_byte(h, '"');
534 		switch (*fmt) {
535 		case 'M':
536 			print_href(h, arg1, arg2, 1);
537 			fmt++;
538 			break;
539 		case 'I':
540 			print_href(h, arg1, NULL, 0);
541 			fmt++;
542 			break;
543 		case 'R':
544 			print_byte(h, '#');
545 			fmt++;
546 			/* FALLTHROUGH */
547 		default:
548 			print_encode(h, arg1, NULL, 1);
549 			break;
550 		}
551 		print_byte(h, '"');
552 	}
553 
554 	/* Print out styles. */
555 
556 	while (*fmt != '\0') {
557 		arg1 = NULL;
558 		su = NULL;
559 
560 		/* First letter: input argument type. */
561 
562 		switch (*fmt++) {
563 		case 'h':
564 			i = va_arg(ap, int);
565 			su = &mysu;
566 			SCALE_HS_INIT(su, i);
567 			break;
568 		case 's':
569 			arg1 = va_arg(ap, char *);
570 			break;
571 		case 'u':
572 			su = va_arg(ap, struct roffsu *);
573 			break;
574 		case 'v':
575 			i = va_arg(ap, int);
576 			su = &mysu;
577 			SCALE_VS_INIT(su, i);
578 			break;
579 		case 'w':
580 		case 'W':
581 			if ((arg2 = va_arg(ap, char *)) == NULL)
582 				break;
583 			su = &mysu;
584 			a2width(arg2, su);
585 			if (fmt[-1] == 'W')
586 				su->scale *= -1.0;
587 			break;
588 		default:
589 			abort();
590 		}
591 
592 		/* Second letter: style name. */
593 
594 		switch (*fmt++) {
595 		case 'b':
596 			attr = "margin-bottom";
597 			break;
598 		case 'h':
599 			attr = "height";
600 			break;
601 		case 'i':
602 			attr = "text-indent";
603 			break;
604 		case 'l':
605 			attr = "margin-left";
606 			break;
607 		case 't':
608 			attr = "margin-top";
609 			break;
610 		case 'w':
611 			attr = "width";
612 			break;
613 		case 'W':
614 			attr = "min-width";
615 			break;
616 		case '?':
617 			attr = arg1;
618 			arg1 = va_arg(ap, char *);
619 			break;
620 		default:
621 			abort();
622 		}
623 		if (su == NULL && arg1 == NULL)
624 			continue;
625 
626 		if (have_style == 1)
627 			print_word(h, " style=\"");
628 		else
629 			print_byte(h, ' ');
630 		print_word(h, attr);
631 		print_byte(h, ':');
632 		print_byte(h, ' ');
633 		if (su != NULL) {
634 			v = su->scale;
635 			if (su->unit == SCALE_MM && (v /= 100.0) == 0.0)
636 				v = 1.0;
637 			else if (su->unit == SCALE_BU)
638 				v /= 24.0;
639 			(void)snprintf(numbuf, sizeof(numbuf), "%.2f", v);
640 			print_word(h, numbuf);
641 			print_word(h, roffscales[su->unit]);
642 		} else
643 			print_word(h, arg1);
644 		print_byte(h, ';');
645 		have_style = 2;
646 	}
647 	if (have_style == 2)
648 		print_byte(h, '"');
649 
650 	va_end(ap);
651 
652 	/* Accommodate for "well-formed" singleton escaping. */
653 
654 	if (HTML_AUTOCLOSE & htmltags[tag].flags)
655 		print_byte(h, '/');
656 
657 	print_byte(h, '>');
658 
659 	if (tflags & HTML_NLBEGIN)
660 		print_endline(h);
661 	else
662 		h->flags |= HTML_NOSPACE;
663 
664 	if (tflags & HTML_INDENT)
665 		h->indent++;
666 	if (tflags & HTML_NOINDENT)
667 		h->noindent++;
668 
669 	return t;
670 }
671 
672 static void
673 print_ctag(struct html *h, struct tag *tag)
674 {
675 	int	 tflags;
676 
677 	/*
678 	 * Remember to close out and nullify the current
679 	 * meta-font and table, if applicable.
680 	 */
681 	if (tag == h->metaf)
682 		h->metaf = NULL;
683 	if (tag == h->tblt)
684 		h->tblt = NULL;
685 
686 	tflags = htmltags[tag->tag].flags;
687 
688 	if (tflags & HTML_INDENT)
689 		h->indent--;
690 	if (tflags & HTML_NOINDENT)
691 		h->noindent--;
692 	if (tflags & HTML_NLEND)
693 		print_endline(h);
694 	print_indent(h);
695 	print_byte(h, '<');
696 	print_byte(h, '/');
697 	print_word(h, htmltags[tag->tag].name);
698 	print_byte(h, '>');
699 	if (tflags & HTML_NLAFTER)
700 		print_endline(h);
701 
702 	h->tag = tag->next;
703 	free(tag);
704 }
705 
706 void
707 print_gen_decls(struct html *h)
708 {
709 	print_word(h, "<!DOCTYPE html>");
710 	print_endline(h);
711 }
712 
713 void
714 print_text(struct html *h, const char *word)
715 {
716 	if (h->col && (h->flags & HTML_NOSPACE) == 0) {
717 		if ( ! (HTML_KEEP & h->flags)) {
718 			if (HTML_PREKEEP & h->flags)
719 				h->flags |= HTML_KEEP;
720 			print_endword(h);
721 		} else
722 			print_word(h, "&#160;");
723 	}
724 
725 	assert(NULL == h->metaf);
726 	switch (h->metac) {
727 	case HTMLFONT_ITALIC:
728 		h->metaf = print_otag(h, TAG_I, "");
729 		break;
730 	case HTMLFONT_BOLD:
731 		h->metaf = print_otag(h, TAG_B, "");
732 		break;
733 	case HTMLFONT_BI:
734 		h->metaf = print_otag(h, TAG_B, "");
735 		print_otag(h, TAG_I, "");
736 		break;
737 	default:
738 		print_indent(h);
739 		break;
740 	}
741 
742 	assert(word);
743 	if ( ! print_encode(h, word, NULL, 0)) {
744 		if ( ! (h->flags & HTML_NONOSPACE))
745 			h->flags &= ~HTML_NOSPACE;
746 		h->flags &= ~HTML_NONEWLINE;
747 	} else
748 		h->flags |= HTML_NOSPACE | HTML_NONEWLINE;
749 
750 	if (h->metaf) {
751 		print_tagq(h, h->metaf);
752 		h->metaf = NULL;
753 	}
754 
755 	h->flags &= ~HTML_IGNDELIM;
756 }
757 
758 void
759 print_tagq(struct html *h, const struct tag *until)
760 {
761 	struct tag	*tag;
762 
763 	while ((tag = h->tag) != NULL) {
764 		print_ctag(h, tag);
765 		if (until && tag == until)
766 			return;
767 	}
768 }
769 
770 void
771 print_stagq(struct html *h, const struct tag *suntil)
772 {
773 	struct tag	*tag;
774 
775 	while ((tag = h->tag) != NULL) {
776 		if (suntil && tag == suntil)
777 			return;
778 		print_ctag(h, tag);
779 	}
780 }
781 
782 void
783 print_paragraph(struct html *h)
784 {
785 	struct tag	*t;
786 
787 	t = print_otag(h, TAG_DIV, "c", "Pp");
788 	print_tagq(h, t);
789 }
790 
791 
792 /***********************************************************************
793  * Low level output functions.
794  * They implement line breaking using a short static buffer.
795  ***********************************************************************/
796 
797 /*
798  * Buffer one HTML output byte.
799  * If the buffer is full, flush and deactivate it and start a new line.
800  * If the buffer is inactive, print directly.
801  */
802 static void
803 print_byte(struct html *h, char c)
804 {
805 	if ((h->flags & HTML_BUFFER) == 0) {
806 		putchar(c);
807 		h->col++;
808 		return;
809 	}
810 
811 	if (h->col + h->bufcol < sizeof(h->buf)) {
812 		h->buf[h->bufcol++] = c;
813 		return;
814 	}
815 
816 	putchar('\n');
817 	h->col = 0;
818 	print_indent(h);
819 	putchar(' ');
820 	putchar(' ');
821 	fwrite(h->buf, h->bufcol, 1, stdout);
822 	putchar(c);
823 	h->col = (h->indent + 1) * 2 + h->bufcol + 1;
824 	h->bufcol = 0;
825 	h->flags &= ~HTML_BUFFER;
826 }
827 
828 /*
829  * If something was printed on the current output line, end it.
830  * Not to be called right after print_indent().
831  */
832 void
833 print_endline(struct html *h)
834 {
835 	if (h->col == 0)
836 		return;
837 
838 	if (h->bufcol) {
839 		putchar(' ');
840 		fwrite(h->buf, h->bufcol, 1, stdout);
841 		h->bufcol = 0;
842 	}
843 	putchar('\n');
844 	h->col = 0;
845 	h->flags |= HTML_NOSPACE;
846 	h->flags &= ~HTML_BUFFER;
847 }
848 
849 /*
850  * Flush the HTML output buffer.
851  * If it is inactive, activate it.
852  */
853 static void
854 print_endword(struct html *h)
855 {
856 	if (h->noindent) {
857 		print_byte(h, ' ');
858 		return;
859 	}
860 
861 	if ((h->flags & HTML_BUFFER) == 0) {
862 		h->col++;
863 		h->flags |= HTML_BUFFER;
864 	} else if (h->bufcol) {
865 		putchar(' ');
866 		fwrite(h->buf, h->bufcol, 1, stdout);
867 		h->col += h->bufcol + 1;
868 	}
869 	h->bufcol = 0;
870 }
871 
872 /*
873  * If at the beginning of a new output line,
874  * perform indentation and mark the line as containing output.
875  * Make sure to really produce some output right afterwards,
876  * but do not use print_otag() for producing it.
877  */
878 static void
879 print_indent(struct html *h)
880 {
881 	size_t	 i;
882 
883 	if (h->col)
884 		return;
885 
886 	if (h->noindent == 0) {
887 		h->col = h->indent * 2;
888 		for (i = 0; i < h->col; i++)
889 			putchar(' ');
890 	}
891 	h->flags &= ~HTML_NOSPACE;
892 }
893 
894 /*
895  * Print or buffer some characters
896  * depending on the current HTML output buffer state.
897  */
898 static void
899 print_word(struct html *h, const char *cp)
900 {
901 	while (*cp != '\0')
902 		print_byte(h, *cp++);
903 }
904 
905 /*
906  * Calculate the scaling unit passed in a `-width' argument.  This uses
907  * either a native scaling unit (e.g., 1i, 2m) or the string length of
908  * the value.
909  */
910 static void
911 a2width(const char *p, struct roffsu *su)
912 {
913 	if (a2roffsu(p, su, SCALE_MAX) < 2) {
914 		su->unit = SCALE_EN;
915 		su->scale = html_strlen(p);
916 	} else if (su->scale < 0.0)
917 		su->scale = 0.0;
918 }
919