[BACK]Return to html.c CVS log [TXT][DIR] Up to [cvsweb.bsd.lv] / mandoc

File: [cvsweb.bsd.lv] / mandoc / html.c (download)

Revision 1.252, Fri Jan 18 14:36:21 2019 UTC (5 years, 2 months ago) by schwarze
Branch: MAIN
Changes since 1.251: +50 -42 lines

The .UR and .MT blocks in man(7) are represented by <a> elements
which establish phrasing context, but they can contain paragraph
breaks (which is relevant for terminal formatting, so we can't just
change the structure of the syntax tree), which are respresented
by <p> elements and cannot occur inside <a>.

Fix this by prematurely closing the <a> element in the HTML formatter.
This menas that the clickable text in HTML output is shorter than
what is represented as the link text in terminal output, but in
HTML, it is frankly impossible to have the clickable area of a
hyperlink extend across a paragraph break.  The difference in
presentation is not a major problem, and besides, paragraph breaks
inside .UR are rather poor style in the first place.

The implementation is quite tricky.  Naively closing out the <a>
prematurely would result in accessing a stale pointer when later
reaching the physical end of the .UR block.  So this commit separates
visual and structural closing of "struct tag" stack items.  Visual
closing means that the HTML element is closed but the "struct tag"
remains on the stack, to avoid later access to a stale pointer and
to avoid closing the same HTML element a second time later.

This also needs reference counting of pointers to "struct tag" stack
items because often more than one child holds a pointer to the same
parent item, and only the outermost child can safely do the physical
closing.

In the whole corpus of nearly half a million manual pages on
man.openbsd.org, this problem occurs in exactly one page: the
groff(1) version 1.20.1 manual contained in DragonFly-3.8.2, which
contains a formatting error triggering the bug.

/*	$Id: html.c,v 1.252 2019/01/18 14:36:21 schwarze Exp $ */
/*
 * Copyright (c) 2008-2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
 * Copyright (c) 2011-2015, 2017-2019 Ingo Schwarze <schwarze@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include "config.h"

#include <sys/types.h>
#include <sys/stat.h>

#include <assert.h>
#include <ctype.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "mandoc_aux.h"
#include "mandoc_ohash.h"
#include "mandoc.h"
#include "roff.h"
#include "out.h"
#include "html.h"
#include "manconf.h"
#include "main.h"

struct	htmldata {
	const char	 *name;
	int		  flags;
#define	HTML_NOSTACK	 (1 << 0)
#define	HTML_AUTOCLOSE	 (1 << 1)
#define	HTML_NLBEFORE	 (1 << 2)
#define	HTML_NLBEGIN	 (1 << 3)
#define	HTML_NLEND	 (1 << 4)
#define	HTML_NLAFTER	 (1 << 5)
#define	HTML_NLAROUND	 (HTML_NLBEFORE | HTML_NLAFTER)
#define	HTML_NLINSIDE	 (HTML_NLBEGIN | HTML_NLEND)
#define	HTML_NLALL	 (HTML_NLAROUND | HTML_NLINSIDE)
#define	HTML_INDENT	 (1 << 6)
#define	HTML_NOINDENT	 (1 << 7)
};

static	const struct htmldata htmltags[TAG_MAX] = {
	{"html",	HTML_NLALL},
	{"head",	HTML_NLALL | HTML_INDENT},
	{"body",	HTML_NLALL},
	{"meta",	HTML_NOSTACK | HTML_AUTOCLOSE | HTML_NLALL},
	{"title",	HTML_NLAROUND},
	{"div",		HTML_NLAROUND},
	{"div",		0},
	{"h1",		HTML_NLAROUND},
	{"h2",		HTML_NLAROUND},
	{"span",	0},
	{"link",	HTML_NOSTACK | HTML_AUTOCLOSE | HTML_NLALL},
	{"br",		HTML_NOSTACK | HTML_AUTOCLOSE | HTML_NLALL},
	{"a",		0},
	{"table",	HTML_NLALL | HTML_INDENT},
	{"tr",		HTML_NLALL | HTML_INDENT},
	{"td",		HTML_NLAROUND},
	{"li",		HTML_NLAROUND | HTML_INDENT},
	{"ul",		HTML_NLALL | HTML_INDENT},
	{"ol",		HTML_NLALL | HTML_INDENT},
	{"dl",		HTML_NLALL | HTML_INDENT},
	{"dt",		HTML_NLAROUND},
	{"dd",		HTML_NLAROUND | HTML_INDENT},
	{"p",		HTML_NLAROUND | HTML_INDENT},
	{"pre",		HTML_NLALL | HTML_NOINDENT},
	{"var",		0},
	{"cite",	0},
	{"b",		0},
	{"i",		0},
	{"code",	0},
	{"small",	0},
	{"style",	HTML_NLALL | HTML_INDENT},
	{"math",	HTML_NLALL | HTML_INDENT},
	{"mrow",	0},
	{"mi",		0},
	{"mn",		0},
	{"mo",		0},
	{"msup",	0},
	{"msub",	0},
	{"msubsup",	0},
	{"mfrac",	0},
	{"msqrt",	0},
	{"mfenced",	0},
	{"mtable",	0},
	{"mtr",		0},
	{"mtd",		0},
	{"munderover",	0},
	{"munder",	0},
	{"mover",	0},
};

/* Avoid duplicate HTML id= attributes. */
static	struct ohash	 id_unique;

static	void	 print_byte(struct html *, char);
static	void	 print_endword(struct html *);
static	void	 print_indent(struct html *);
static	void	 print_word(struct html *, const char *);

static	void	 print_ctag(struct html *, struct tag *);
static	int	 print_escape(struct html *, char);
static	int	 print_encode(struct html *, const char *, const char *, int);
static	void	 print_href(struct html *, const char *, const char *, int);


void *
html_alloc(const struct manoutput *outopts)
{
	struct html	*h;

	h = mandoc_calloc(1, sizeof(struct html));

	h->tag = NULL;
	h->style = outopts->style;
	if ((h->base_man1 = outopts->man) == NULL)
		h->base_man2 = NULL;
	else if ((h->base_man2 = strchr(h->base_man1, ';')) != NULL)
		*h->base_man2++ = '\0';
	h->base_includes = outopts->includes;
	if (outopts->fragment)
		h->oflags |= HTML_FRAGMENT;
	if (outopts->toc)
		h->oflags |= HTML_TOC;

	mandoc_ohash_init(&id_unique, 4, 0);

	return h;
}

void
html_free(void *p)
{
	struct tag	*tag;
	struct html	*h;
	char		*cp;
	unsigned int	 slot;

	h = (struct html *)p;
	while ((tag = h->tag) != NULL) {
		h->tag = tag->next;
		free(tag);
	}
	free(h);

	cp = ohash_first(&id_unique, &slot);
	while (cp != NULL) {
		free(cp);
		cp = ohash_next(&id_unique, &slot);
	}
	ohash_delete(&id_unique);
}

void
print_gen_head(struct html *h)
{
	struct tag	*t;

	print_otag(h, TAG_META, "?", "charset", "utf-8");
	if (h->style != NULL) {
		print_otag(h, TAG_LINK, "?h??", "rel", "stylesheet",
		    h->style, "type", "text/css", "media", "all");
		return;
	}

	/*
	 * Print a minimal embedded style sheet.
	 */

	t = print_otag(h, TAG_STYLE, "");
	print_text(h, "table.head, table.foot { width: 100%; }");
	print_endline(h);
	print_text(h, "td.head-rtitle, td.foot-os { text-align: right; }");
	print_endline(h);
	print_text(h, "td.head-vol { text-align: center; }");
	print_endline(h);
	print_text(h, "div.Pp { margin: 1ex 0ex; }");
	print_endline(h);
	print_text(h, "div.Nd, div.Bf, div.Op { display: inline; }");
	print_endline(h);
	print_text(h, "span.Pa, span.Ad { font-style: italic; }");
	print_endline(h);
	print_text(h, "span.Ms { font-weight: bold; }");
	print_endline(h);
	print_text(h, "dl.Bl-diag ");
	print_byte(h, '>');
	print_text(h, " dt { font-weight: bold; }");
	print_endline(h);
	print_text(h, "code.Nm, code.Fl, code.Cm, code.Ic, "
	    "code.In, code.Fd, code.Fn,");
	print_endline(h);
	print_text(h, "code.Cd { font-weight: bold; "
	    "font-family: inherit; }");
	print_tagq(h, t);
}

void
print_metaf(struct html *h, enum mandoc_esc deco)
{
	enum htmlfont	 font;

	switch (deco) {
	case ESCAPE_FONTPREV:
		font = h->metal;
		break;
	case ESCAPE_FONTITALIC:
		font = HTMLFONT_ITALIC;
		break;
	case ESCAPE_FONTBOLD:
		font = HTMLFONT_BOLD;
		break;
	case ESCAPE_FONTBI:
		font = HTMLFONT_BI;
		break;
	case ESCAPE_FONTCW:
		font = HTMLFONT_CW;
		break;
	case ESCAPE_FONT:
	case ESCAPE_FONTROMAN:
		font = HTMLFONT_NONE;
		break;
	default:
		return;
	}

	if (h->metaf) {
		print_tagq(h, h->metaf);
		h->metaf = NULL;
	}

	h->metal = h->metac;
	h->metac = font;

	switch (font) {
	case HTMLFONT_ITALIC:
		h->metaf = print_otag(h, TAG_I, "");
		break;
	case HTMLFONT_BOLD:
		h->metaf = print_otag(h, TAG_B, "");
		break;
	case HTMLFONT_BI:
		h->metaf = print_otag(h, TAG_B, "");
		print_otag(h, TAG_I, "");
		break;
	case HTMLFONT_CW:
		h->metaf = print_otag(h, TAG_SPAN, "c", "Li");
		break;
	default:
		break;
	}
}

void
html_close_paragraph(struct html *h)
{
	struct tag	*t;

	for (t = h->tag; t != NULL && t->closed == 0; t = t->next) {
		switch(t->tag) {
		case TAG_P:
		case TAG_PRE:
			print_tagq(h, t);
			break;
		case TAG_A:
			print_tagq(h, t);
			continue;
		default:
			continue;
		}
		break;
	}
}

/*
 * ROFF_nf switches to no-fill mode, ROFF_fi to fill mode.
 * TOKEN_NONE does not switch.  The old mode is returned.
 */
enum roff_tok
html_fillmode(struct html *h, enum roff_tok want)
{
	struct tag	*t;
	enum roff_tok	 had;

	for (t = h->tag; t != NULL; t = t->next)
		if (t->tag == TAG_PRE)
			break;

	had = t == NULL ? ROFF_fi : ROFF_nf;

	if (want != had) {
		switch (want) {
		case ROFF_fi:
			print_tagq(h, t);
			break;
		case ROFF_nf:
			html_close_paragraph(h);
			print_otag(h, TAG_PRE, "");
			break;
		case TOKEN_NONE:
			break;
		default:
			abort();
		}
	}
	return had;
}

char *
html_make_id(const struct roff_node *n, int unique)
{
	const struct roff_node	*nch;
	char			*buf, *bufs, *cp;
	unsigned int		 slot;
	int			 suffix;

	for (nch = n->child; nch != NULL; nch = nch->next)
		if (nch->type != ROFFT_TEXT)
			return NULL;

	buf = NULL;
	deroff(&buf, n);
	if (buf == NULL)
		return NULL;

	/*
	 * In ID attributes, only use ASCII characters that are
	 * permitted in URL-fragment strings according to the
	 * explicit list at:
	 * https://url.spec.whatwg.org/#url-fragment-string
	 */

	for (cp = buf; *cp != '\0'; cp++)
		if (isalnum((unsigned char)*cp) == 0 &&
		    strchr("!$&'()*+,-./:;=?@_~", *cp) == NULL)
			*cp = '_';

	if (unique == 0)
		return buf;

	/* Avoid duplicate HTML id= attributes. */

	bufs = NULL;
	suffix = 1;
	slot = ohash_qlookup(&id_unique, buf);
	cp = ohash_find(&id_unique, slot);
	if (cp != NULL) {
		while (cp != NULL) {
			free(bufs);
			if (++suffix > 127) {
				free(buf);
				return NULL;
			}
			mandoc_asprintf(&bufs, "%s_%d", buf, suffix);
			slot = ohash_qlookup(&id_unique, bufs);
			cp = ohash_find(&id_unique, slot);
		}
		free(buf);
		buf = bufs;
	}
	ohash_insert(&id_unique, slot, buf);
	return buf;
}

static int
print_escape(struct html *h, char c)
{

	switch (c) {
	case '<':
		print_word(h, "&lt;");
		break;
	case '>':
		print_word(h, "&gt;");
		break;
	case '&':
		print_word(h, "&amp;");
		break;
	case '"':
		print_word(h, "&quot;");
		break;
	case ASCII_NBRSP:
		print_word(h, "&nbsp;");
		break;
	case ASCII_HYPH:
		print_byte(h, '-');
		break;
	case ASCII_BREAK:
		break;
	default:
		return 0;
	}
	return 1;
}

static int
print_encode(struct html *h, const char *p, const char *pend, int norecurse)
{
	char		 numbuf[16];
	const char	*seq;
	size_t		 sz;
	int		 c, len, breakline, nospace;
	enum mandoc_esc	 esc;
	static const char rejs[10] = { ' ', '\\', '<', '>', '&', '"',
		ASCII_NBRSP, ASCII_HYPH, ASCII_BREAK, '\0' };

	if (pend == NULL)
		pend = strchr(p, '\0');

	breakline = 0;
	nospace = 0;

	while (p < pend) {
		if (HTML_SKIPCHAR & h->flags && '\\' != *p) {
			h->flags &= ~HTML_SKIPCHAR;
			p++;
			continue;
		}

		for (sz = strcspn(p, rejs); sz-- && p < pend; p++)
			print_byte(h, *p);

		if (breakline &&
		    (p >= pend || *p == ' ' || *p == ASCII_NBRSP)) {
			print_otag(h, TAG_BR, "");
			breakline = 0;
			while (p < pend && (*p == ' ' || *p == ASCII_NBRSP))
				p++;
			continue;
		}

		if (p >= pend)
			break;

		if (*p == ' ') {
			print_endword(h);
			p++;
			continue;
		}

		if (print_escape(h, *p++))
			continue;

		esc = mandoc_escape(&p, &seq, &len);
		switch (esc) {
		case ESCAPE_FONT:
		case ESCAPE_FONTPREV:
		case ESCAPE_FONTBOLD:
		case ESCAPE_FONTITALIC:
		case ESCAPE_FONTBI:
		case ESCAPE_FONTCW:
		case ESCAPE_FONTROMAN:
			if (0 == norecurse) {
				h->flags |= HTML_NOSPACE;
				print_metaf(h, esc);
				h->flags &= ~HTML_NOSPACE;
			}
			continue;
		case ESCAPE_SKIPCHAR:
			h->flags |= HTML_SKIPCHAR;
			continue;
		case ESCAPE_ERROR:
			continue;
		default:
			break;
		}

		if (h->flags & HTML_SKIPCHAR) {
			h->flags &= ~HTML_SKIPCHAR;
			continue;
		}

		switch (esc) {
		case ESCAPE_UNICODE:
			/* Skip past "u" header. */
			c = mchars_num2uc(seq + 1, len - 1);
			break;
		case ESCAPE_NUMBERED:
			c = mchars_num2char(seq, len);
			if (c < 0)
				continue;
			break;
		case ESCAPE_SPECIAL:
			c = mchars_spec2cp(seq, len);
			if (c <= 0)
				continue;
			break;
		case ESCAPE_UNDEF:
			c = *seq;
			break;
		case ESCAPE_DEVICE:
			print_word(h, "html");
			continue;
		case ESCAPE_BREAK:
			breakline = 1;
			continue;
		case ESCAPE_NOSPACE:
			if ('\0' == *p)
				nospace = 1;
			continue;
		case ESCAPE_OVERSTRIKE:
			if (len == 0)
				continue;
			c = seq[len - 1];
			break;
		default:
			continue;
		}
		if ((c < 0x20 && c != 0x09) ||
		    (c > 0x7E && c < 0xA0))
			c = 0xFFFD;
		if (c > 0x7E) {
			(void)snprintf(numbuf, sizeof(numbuf), "&#x%.4X;", c);
			print_word(h, numbuf);
		} else if (print_escape(h, c) == 0)
			print_byte(h, c);
	}

	return nospace;
}

static void
print_href(struct html *h, const char *name, const char *sec, int man)
{
	struct stat	 sb;
	const char	*p, *pp;
	char		*filename;

	if (man) {
		pp = h->base_man1;
		if (h->base_man2 != NULL) {
			mandoc_asprintf(&filename, "%s.%s", name, sec);
			if (stat(filename, &sb) == -1)
				pp = h->base_man2;
			free(filename);
		}
	} else
		pp = h->base_includes;

	while ((p = strchr(pp, '%')) != NULL) {
		print_encode(h, pp, p, 1);
		if (man && p[1] == 'S') {
			if (sec == NULL)
				print_byte(h, '1');
			else
				print_encode(h, sec, NULL, 1);
		} else if ((man && p[1] == 'N') ||
		    (man == 0 && p[1] == 'I'))
			print_encode(h, name, NULL, 1);
		else
			print_encode(h, p, p + 2, 1);
		pp = p + 2;
	}
	if (*pp != '\0')
		print_encode(h, pp, NULL, 1);
}

struct tag *
print_otag(struct html *h, enum htmltag tag, const char *fmt, ...)
{
	va_list		 ap;
	struct tag	*t;
	const char	*attr;
	char		*arg1, *arg2;
	int		 style_written, tflags;

	tflags = htmltags[tag].flags;

	/* Push this tag onto the stack of open scopes. */

	if ((tflags & HTML_NOSTACK) == 0) {
		t = mandoc_malloc(sizeof(struct tag));
		t->tag = tag;
		t->next = h->tag;
		t->refcnt = 0;
		t->closed = 0;
		h->tag = t;
	} else
		t = NULL;

	if (tflags & HTML_NLBEFORE)
		print_endline(h);
	if (h->col == 0)
		print_indent(h);
	else if ((h->flags & HTML_NOSPACE) == 0) {
		if (h->flags & HTML_KEEP)
			print_word(h, "&#x00A0;");
		else {
			if (h->flags & HTML_PREKEEP)
				h->flags |= HTML_KEEP;
			print_endword(h);
		}
	}

	if ( ! (h->flags & HTML_NONOSPACE))
		h->flags &= ~HTML_NOSPACE;
	else
		h->flags |= HTML_NOSPACE;

	/* Print out the tag name and attributes. */

	print_byte(h, '<');
	print_word(h, htmltags[tag].name);

	va_start(ap, fmt);

	while (*fmt != '\0' && *fmt != 's') {

		/* Parse attributes and arguments. */

		arg1 = va_arg(ap, char *);
		arg2 = NULL;
		switch (*fmt++) {
		case 'c':
			attr = "class";
			break;
		case 'h':
			attr = "href";
			break;
		case 'i':
			attr = "id";
			break;
		case '?':
			attr = arg1;
			arg1 = va_arg(ap, char *);
			break;
		default:
			abort();
		}
		if (*fmt == 'M')
			arg2 = va_arg(ap, char *);
		if (arg1 == NULL)
			continue;

		/* Print the attributes. */

		print_byte(h, ' ');
		print_word(h, attr);
		print_byte(h, '=');
		print_byte(h, '"');
		switch (*fmt) {
		case 'I':
			print_href(h, arg1, NULL, 0);
			fmt++;
			break;
		case 'M':
			print_href(h, arg1, arg2, 1);
			fmt++;
			break;
		case 'R':
			print_byte(h, '#');
			print_encode(h, arg1, NULL, 1);
			fmt++;
			break;
		default:
			print_encode(h, arg1, NULL, 1);
			break;
		}
		print_byte(h, '"');
	}

	style_written = 0;
	while (*fmt++ == 's') {
		arg1 = va_arg(ap, char *);
		arg2 = va_arg(ap, char *);
		if (arg2 == NULL)
			continue;
		print_byte(h, ' ');
		if (style_written == 0) {
			print_word(h, "style=\"");
			style_written = 1;
		}
		print_word(h, arg1);
		print_byte(h, ':');
		print_byte(h, ' ');
		print_word(h, arg2);
		print_byte(h, ';');
	}
	if (style_written)
		print_byte(h, '"');

	va_end(ap);

	/* Accommodate for "well-formed" singleton escaping. */

	if (HTML_AUTOCLOSE & htmltags[tag].flags)
		print_byte(h, '/');

	print_byte(h, '>');

	if (tflags & HTML_NLBEGIN)
		print_endline(h);
	else
		h->flags |= HTML_NOSPACE;

	if (tflags & HTML_INDENT)
		h->indent++;
	if (tflags & HTML_NOINDENT)
		h->noindent++;

	return t;
}

static void
print_ctag(struct html *h, struct tag *tag)
{
	int	 tflags;

	if (tag->closed == 0) {
		tag->closed = 1;
		if (tag == h->metaf)
			h->metaf = NULL;
		if (tag == h->tblt)
			h->tblt = NULL;

		tflags = htmltags[tag->tag].flags;
		if (tflags & HTML_INDENT)
			h->indent--;
		if (tflags & HTML_NOINDENT)
			h->noindent--;
		if (tflags & HTML_NLEND)
			print_endline(h);
		print_indent(h);
		print_byte(h, '<');
		print_byte(h, '/');
		print_word(h, htmltags[tag->tag].name);
		print_byte(h, '>');
		if (tflags & HTML_NLAFTER)
			print_endline(h);
	}
	if (tag->refcnt == 0) {
		h->tag = tag->next;
		free(tag);
	}
}

void
print_gen_decls(struct html *h)
{
	print_word(h, "<!DOCTYPE html>");
	print_endline(h);
}

void
print_gen_comment(struct html *h, struct roff_node *n)
{
	int	 wantblank;

	print_word(h, "<!-- This is an automatically generated file."
	    "  Do not edit.");
	h->indent = 1;
	wantblank = 0;
	while (n != NULL && n->type == ROFFT_COMMENT) {
		if (strstr(n->string, "-->") == NULL &&
		    (wantblank || *n->string != '\0')) {
			print_endline(h);
			print_indent(h);
			print_word(h, n->string);
			wantblank = *n->string != '\0';
		}
		n = n->next;
	}
	if (wantblank)
		print_endline(h);
	print_word(h, " -->");
	print_endline(h);
	h->indent = 0;
}

void
print_text(struct html *h, const char *word)
{
	if (h->col && (h->flags & HTML_NOSPACE) == 0) {
		if ( ! (HTML_KEEP & h->flags)) {
			if (HTML_PREKEEP & h->flags)
				h->flags |= HTML_KEEP;
			print_endword(h);
		} else
			print_word(h, "&#x00A0;");
	}

	assert(NULL == h->metaf);
	switch (h->metac) {
	case HTMLFONT_ITALIC:
		h->metaf = print_otag(h, TAG_I, "");
		break;
	case HTMLFONT_BOLD:
		h->metaf = print_otag(h, TAG_B, "");
		break;
	case HTMLFONT_BI:
		h->metaf = print_otag(h, TAG_B, "");
		print_otag(h, TAG_I, "");
		break;
	case HTMLFONT_CW:
		h->metaf = print_otag(h, TAG_SPAN, "c", "Li");
		break;
	default:
		print_indent(h);
		break;
	}

	assert(word);
	if ( ! print_encode(h, word, NULL, 0)) {
		if ( ! (h->flags & HTML_NONOSPACE))
			h->flags &= ~HTML_NOSPACE;
		h->flags &= ~HTML_NONEWLINE;
	} else
		h->flags |= HTML_NOSPACE | HTML_NONEWLINE;

	if (h->metaf) {
		print_tagq(h, h->metaf);
		h->metaf = NULL;
	}

	h->flags &= ~HTML_IGNDELIM;
}

void
print_tagq(struct html *h, const struct tag *until)
{
	struct tag	*this, *next;

	for (this = h->tag; this != NULL; this = next) {
		next = this == until ? NULL : this->next;
		print_ctag(h, this);
	}
}

/*
 * Close out all open elements up to but excluding suntil.
 * Note that a paragraph just inside stays open together with it
 * because paragraphs include subsequent phrasing content.
 */
void
print_stagq(struct html *h, const struct tag *suntil)
{
	struct tag	*this, *next;

	for (this = h->tag; this != NULL; this = next) {
		next = this->next;
		if (this == suntil || (next == suntil &&
		    (this->tag == TAG_P || this->tag == TAG_PRE)))
			break;
		print_ctag(h, this);
	}
}


/***********************************************************************
 * Low level output functions.
 * They implement line breaking using a short static buffer.
 ***********************************************************************/

/*
 * Buffer one HTML output byte.
 * If the buffer is full, flush and deactivate it and start a new line.
 * If the buffer is inactive, print directly.
 */
static void
print_byte(struct html *h, char c)
{
	if ((h->flags & HTML_BUFFER) == 0) {
		putchar(c);
		h->col++;
		return;
	}

	if (h->col + h->bufcol < sizeof(h->buf)) {
		h->buf[h->bufcol++] = c;
		return;
	}

	putchar('\n');
	h->col = 0;
	print_indent(h);
	putchar(' ');
	putchar(' ');
	fwrite(h->buf, h->bufcol, 1, stdout);
	putchar(c);
	h->col = (h->indent + 1) * 2 + h->bufcol + 1;
	h->bufcol = 0;
	h->flags &= ~HTML_BUFFER;
}

/*
 * If something was printed on the current output line, end it.
 * Not to be called right after print_indent().
 */
void
print_endline(struct html *h)
{
	if (h->col == 0)
		return;

	if (h->bufcol) {
		putchar(' ');
		fwrite(h->buf, h->bufcol, 1, stdout);
		h->bufcol = 0;
	}
	putchar('\n');
	h->col = 0;
	h->flags |= HTML_NOSPACE;
	h->flags &= ~HTML_BUFFER;
}

/*
 * Flush the HTML output buffer.
 * If it is inactive, activate it.
 */
static void
print_endword(struct html *h)
{
	if (h->noindent) {
		print_byte(h, ' ');
		return;
	}

	if ((h->flags & HTML_BUFFER) == 0) {
		h->col++;
		h->flags |= HTML_BUFFER;
	} else if (h->bufcol) {
		putchar(' ');
		fwrite(h->buf, h->bufcol, 1, stdout);
		h->col += h->bufcol + 1;
	}
	h->bufcol = 0;
}

/*
 * If at the beginning of a new output line,
 * perform indentation and mark the line as containing output.
 * Make sure to really produce some output right afterwards,
 * but do not use print_otag() for producing it.
 */
static void
print_indent(struct html *h)
{
	size_t	 i;

	if (h->col)
		return;

	if (h->noindent == 0) {
		h->col = h->indent * 2;
		for (i = 0; i < h->col; i++)
			putchar(' ');
	}
	h->flags &= ~HTML_NOSPACE;
}

/*
 * Print or buffer some characters
 * depending on the current HTML output buffer state.
 */
static void
print_word(struct html *h, const char *cp)
{
	while (*cp != '\0')
		print_byte(h, *cp++);
}