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Revision 1.22, Thu Sep 3 20:43:15 2020 UTC (13 months, 2 weeks ago) by schwarze
Branch: MAIN
Changes since 1.21: +13 -5 lines

Fix two issues with .po (page offset) formatting:
1. Truncate excessive offsets to a width reasonable in the context
of manual pages instead of printing excessively long lines
and sometimes causing assertion failures;
found in an afl run performed by Jan Schreiber <jes at posteo dot de>.
2. Remember both the requested and the applied page offset; otherwise,
subtracting an excessive width, then adding it again, would end up
with an incorrectly large offset.
While here, simplify the code by reverting the previous offset up front,
and also add some comments to make the general ideas easier to understand.

/* $OpenBSD: roff_term.c,v 1.20 2020/09/03 17:37:06 schwarze Exp $ */
/*
 * Copyright (c) 2010,2014,2015,2017-2020 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 AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR 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 <assert.h>
#include <stdio.h>
#include <string.h>

#include "mandoc.h"
#include "roff.h"
#include "out.h"
#include "term.h"

#define	ROFF_TERM_ARGS struct termp *p, const struct roff_node *n

typedef	void	(*roff_term_pre_fp)(ROFF_TERM_ARGS);

static	void	  roff_term_pre_br(ROFF_TERM_ARGS);
static	void	  roff_term_pre_ce(ROFF_TERM_ARGS);
static	void	  roff_term_pre_ft(ROFF_TERM_ARGS);
static	void	  roff_term_pre_ll(ROFF_TERM_ARGS);
static	void	  roff_term_pre_mc(ROFF_TERM_ARGS);
static	void	  roff_term_pre_po(ROFF_TERM_ARGS);
static	void	  roff_term_pre_sp(ROFF_TERM_ARGS);
static	void	  roff_term_pre_ta(ROFF_TERM_ARGS);
static	void	  roff_term_pre_ti(ROFF_TERM_ARGS);

static	const roff_term_pre_fp roff_term_pre_acts[ROFF_MAX] = {
	roff_term_pre_br,  /* br */
	roff_term_pre_ce,  /* ce */
	roff_term_pre_br,  /* fi */
	roff_term_pre_ft,  /* ft */
	roff_term_pre_ll,  /* ll */
	roff_term_pre_mc,  /* mc */
	roff_term_pre_br,  /* nf */
	roff_term_pre_po,  /* po */
	roff_term_pre_ce,  /* rj */
	roff_term_pre_sp,  /* sp */
	roff_term_pre_ta,  /* ta */
	roff_term_pre_ti,  /* ti */
};


void
roff_term_pre(struct termp *p, const struct roff_node *n)
{
	assert(n->tok < ROFF_MAX);
	(*roff_term_pre_acts[n->tok])(p, n);
}

static void
roff_term_pre_br(ROFF_TERM_ARGS)
{
	term_newln(p);
	if (p->flags & TERMP_BRIND) {
		p->tcol->offset = p->tcol->rmargin;
		p->tcol->rmargin = p->maxrmargin;
		p->trailspace = 0;
		p->flags &= ~(TERMP_NOBREAK | TERMP_BRIND);
		p->flags |= TERMP_NOSPACE;
	}
}

static void
roff_term_pre_ce(ROFF_TERM_ARGS)
{
	const struct roff_node	*nc1, *nc2;

	roff_term_pre_br(p, n);
	p->flags |= n->tok == ROFF_ce ? TERMP_CENTER : TERMP_RIGHT;
	nc1 = n->child->next;
	while (nc1 != NULL) {
		nc2 = nc1;
		do {
			nc2 = nc2->next;
		} while (nc2 != NULL && (nc2->type != ROFFT_TEXT ||
		    (nc2->flags & NODE_LINE) == 0));
		while (nc1 != nc2) {
			if (nc1->type == ROFFT_TEXT)
				term_word(p, nc1->string);
			else
				roff_term_pre(p, nc1);
			nc1 = nc1->next;
		}
		p->flags |= TERMP_NOSPACE;
		term_flushln(p);
	}
	p->flags &= ~(TERMP_CENTER | TERMP_RIGHT);
}

static void
roff_term_pre_ft(ROFF_TERM_ARGS)
{
	const char	*cp;

	cp = n->child->string;
	switch (mandoc_font(cp, (int)strlen(cp))) {
	case ESCAPE_FONTBOLD:
		term_fontrepl(p, TERMFONT_BOLD);
		break;
	case ESCAPE_FONTITALIC:
		term_fontrepl(p, TERMFONT_UNDER);
		break;
	case ESCAPE_FONTBI:
		term_fontrepl(p, TERMFONT_BI);
		break;
	case ESCAPE_FONTPREV:
		term_fontlast(p);
		break;
	case ESCAPE_FONTROMAN:
	case ESCAPE_FONTCW:
		term_fontrepl(p, TERMFONT_NONE);
		break;
	default:
		break;
	}
}

static void
roff_term_pre_ll(ROFF_TERM_ARGS)
{
	term_setwidth(p, n->child != NULL ? n->child->string : NULL);
}

static void
roff_term_pre_mc(ROFF_TERM_ARGS)
{
	if (p->col) {
		p->flags |= TERMP_NOBREAK;
		term_flushln(p);
		p->flags &= ~(TERMP_NOBREAK | TERMP_NOSPACE);
	}
	if (n->child != NULL) {
		p->mc = n->child->string;
		p->flags |= TERMP_NEWMC;
	} else
		p->flags |= TERMP_ENDMC;
}

static void
roff_term_pre_po(ROFF_TERM_ARGS)
{
	struct roffsu	 su;
	static int	 po, pouse, polast;
	int		 ponew;

	/* Revert the currently active page offset. */
	p->tcol->offset -= pouse;

	/* Determine the requested page offset. */
	if (n->child != NULL &&
	    a2roffsu(n->child->string, &su, SCALE_EM) != NULL) {
		ponew = term_hen(p, &su);
		if (*n->child->string == '+' ||
		    *n->child->string == '-')
			ponew += po;
	} else
		ponew = polast;

	/* Remeber both the previous and the newly requested offset. */
	polast = po;
	po = ponew;

	/* Truncate to the range [-offset, 60], remember, and apply it. */
	pouse = po >= 60 ? 60 :
	    po < -(int)p->tcol->offset ? -p->tcol->offset : po;
	p->tcol->offset += pouse;
}

static void
roff_term_pre_sp(ROFF_TERM_ARGS)
{
	struct roffsu	 su;
	int		 len;

	if (n->child != NULL) {
		if (a2roffsu(n->child->string, &su, SCALE_VS) == NULL)
			su.scale = 1.0;
		len = term_vspan(p, &su);
	} else
		len = 1;

	if (len < 0)
		p->skipvsp -= len;
	else
		while (len--)
			term_vspace(p);

	roff_term_pre_br(p, n);
}

static void
roff_term_pre_ta(ROFF_TERM_ARGS)
{
	term_tab_set(p, NULL);
	for (n = n->child; n != NULL; n = n->next)
		term_tab_set(p, n->string);
}

static void
roff_term_pre_ti(ROFF_TERM_ARGS)
{
	struct roffsu	 su;
	const char	*cp;
	const size_t	 maxoff = 72;
	int		 len, sign;

	roff_term_pre_br(p, n);

	if (n->child == NULL)
		return;
	cp = n->child->string;
	if (*cp == '+') {
		sign = 1;
		cp++;
	} else if (*cp == '-') {
		sign = -1;
		cp++;
	} else
		sign = 0;

	if (a2roffsu(cp, &su, SCALE_EM) == NULL)
		return;
	len = term_hen(p, &su);

	switch (sign) {
	case 1:
		if (p->tcol->offset + len <= maxoff)
			p->ti = len;
		else if (p->tcol->offset < maxoff)
			p->ti = maxoff - p->tcol->offset;
		else
			p->ti = 0;
		break;
	case -1:
		if ((size_t)len < p->tcol->offset)
			p->ti = -len;
		else
			p->ti = -p->tcol->offset;
		break;
	default:
		if ((size_t)len > maxoff)
			len = maxoff;
		p->ti = len - p->tcol->offset;
		break;
	}
	p->tcol->offset += p->ti;
}