/*	$Id$ */
/*
 * Copyright (c) 2008, 2009 Kristaps Dzonsons <kristaps@kth.se>
 *
 * 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 <sys/utsname.h>

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "libmdoc.h"

#define	POST_ARGS struct mdoc *m, struct mdoc_node *n
#define	PRE_ARGS  struct mdoc *m, const struct mdoc_node *n

struct	actions {
	int	(*pre)(PRE_ARGS);
	int	(*post)(POST_ARGS);
};

static	int	  post_ar(POST_ARGS);
static	int	  post_at(POST_ARGS);
static	int	  post_bl(POST_ARGS);
static	int	  post_bl_head(POST_ARGS);
static	int	  post_bl_tagwidth(POST_ARGS);
static	int	  post_bl_width(POST_ARGS);
static	int	  post_dd(POST_ARGS);
static	int	  post_display(POST_ARGS);
static	int	  post_dt(POST_ARGS);
static	int	  post_lb(POST_ARGS);
static	int	  post_nm(POST_ARGS);
static	int	  post_os(POST_ARGS);
static	int	  post_prol(POST_ARGS);
static	int	  post_sh(POST_ARGS);
static	int	  post_st(POST_ARGS);
static	int	  post_std(POST_ARGS);
static	int	  post_tilde(POST_ARGS);

static	int	  pre_bd(PRE_ARGS);
static	int	  pre_bl(PRE_ARGS);
static	int	  pre_dl(PRE_ARGS);
static	int	  pre_offset(PRE_ARGS);

static	const struct actions mdoc_actions[MDOC_MAX] = {
	{ NULL, NULL }, /* Ap */
	{ NULL, post_dd }, /* Dd */ 
	{ NULL, post_dt }, /* Dt */ 
	{ NULL, post_os }, /* Os */ 
	{ NULL, post_sh }, /* Sh */ 
	{ NULL, NULL }, /* Ss */ 
	{ NULL, NULL }, /* Pp */ 
	{ NULL, NULL }, /* D1 */
	{ pre_dl, post_display }, /* Dl */
	{ pre_bd, post_display }, /* Bd */ 
	{ NULL, NULL }, /* Ed */
	{ pre_bl, post_bl }, /* Bl */ 
	{ NULL, NULL }, /* El */
	{ NULL, NULL }, /* It */
	{ NULL, NULL }, /* Ad */ 
	{ NULL, NULL }, /* An */
	{ NULL, post_ar }, /* Ar */
	{ NULL, NULL }, /* Cd */
	{ NULL, NULL }, /* Cm */
	{ NULL, NULL }, /* Dv */ 
	{ NULL, NULL }, /* Er */ 
	{ NULL, NULL }, /* Ev */ 
	{ NULL, post_std }, /* Ex */
	{ NULL, NULL }, /* Fa */ 
	{ NULL, NULL }, /* Fd */ 
	{ NULL, NULL }, /* Fl */
	{ NULL, NULL }, /* Fn */ 
	{ NULL, NULL }, /* Ft */ 
	{ NULL, NULL }, /* Ic */ 
	{ NULL, NULL }, /* In */ 
	{ NULL, NULL }, /* Li */
	{ NULL, NULL }, /* Nd */ 
	{ NULL, post_nm }, /* Nm */ 
	{ NULL, NULL }, /* Op */
	{ NULL, NULL }, /* Ot */
	{ NULL, post_tilde }, /* Pa */
	{ NULL, post_std }, /* Rv */
	{ NULL, post_st }, /* St */
	{ NULL, NULL }, /* Va */
	{ NULL, NULL }, /* Vt */ 
	{ NULL, NULL }, /* Xr */
	{ NULL, NULL }, /* %A */
	{ NULL, NULL }, /* %B */
	{ NULL, NULL }, /* %D */
	{ NULL, NULL }, /* %I */
	{ NULL, NULL }, /* %J */
	{ NULL, NULL }, /* %N */
	{ NULL, NULL }, /* %O */
	{ NULL, NULL }, /* %P */
	{ NULL, NULL }, /* %R */
	{ NULL, NULL }, /* %T */
	{ NULL, NULL }, /* %V */
	{ NULL, NULL }, /* Ac */
	{ NULL, NULL }, /* Ao */
	{ NULL, NULL }, /* Aq */
	{ NULL, post_at }, /* At */ 
	{ NULL, NULL }, /* Bc */
	{ NULL, NULL }, /* Bf */ 
	{ NULL, NULL }, /* Bo */
	{ NULL, NULL }, /* Bq */
	{ NULL, NULL }, /* Bsx */
	{ NULL, NULL }, /* Bx */
	{ NULL, NULL }, /* Db */
	{ NULL, NULL }, /* Dc */
	{ NULL, NULL }, /* Do */
	{ NULL, NULL }, /* Dq */
	{ NULL, NULL }, /* Ec */
	{ NULL, NULL }, /* Ef */
	{ NULL, NULL }, /* Em */ 
	{ NULL, NULL }, /* Eo */
	{ NULL, NULL }, /* Fx */
	{ NULL, NULL }, /* Ms */
	{ NULL, NULL }, /* No */
	{ NULL, NULL }, /* Ns */
	{ NULL, NULL }, /* Nx */
	{ NULL, NULL }, /* Ox */
	{ NULL, NULL }, /* Pc */
	{ NULL, NULL }, /* Pf */
	{ NULL, NULL }, /* Po */
	{ NULL, NULL }, /* Pq */
	{ NULL, NULL }, /* Qc */
	{ NULL, NULL }, /* Ql */
	{ NULL, NULL }, /* Qo */
	{ NULL, NULL }, /* Qq */
	{ NULL, NULL }, /* Re */
	{ NULL, NULL }, /* Rs */
	{ NULL, NULL }, /* Sc */
	{ NULL, NULL }, /* So */
	{ NULL, NULL }, /* Sq */
	{ NULL, NULL }, /* Sm */
	{ NULL, NULL }, /* Sx */
	{ NULL, NULL }, /* Sy */
	{ NULL, NULL }, /* Tn */
	{ NULL, NULL }, /* Ux */
	{ NULL, NULL }, /* Xc */
	{ NULL, NULL }, /* Xo */
	{ NULL, NULL }, /* Fo */ 
	{ NULL, NULL }, /* Fc */ 
	{ NULL, NULL }, /* Oo */
	{ NULL, NULL }, /* Oc */
	{ NULL, NULL }, /* Bk */
	{ NULL, NULL }, /* Ek */
	{ NULL, NULL }, /* Bt */
	{ NULL, NULL }, /* Hf */
	{ NULL, NULL }, /* Fr */
	{ NULL, NULL }, /* Ud */
	{ NULL, post_lb }, /* Lb */
	{ NULL, NULL }, /* Lp */
	{ NULL, post_tilde }, /* Lk */
	{ NULL, NULL }, /* Mt */
	{ NULL, NULL }, /* Brq */
	{ NULL, NULL }, /* Bro */
	{ NULL, NULL }, /* Brc */
	{ NULL, NULL }, /* %C */
	{ NULL, NULL }, /* Es */
	{ NULL, NULL }, /* En */
	{ NULL, NULL }, /* Dx */
	{ NULL, NULL }, /* %Q */
	{ NULL, NULL }, /* br */
	{ NULL, NULL }, /* sp */
};

static	int	  concat(struct mdoc *, const struct mdoc_node *, 
			char *, size_t);

#ifdef __linux__
extern	size_t	  strlcat(char *, const char *, size_t);
#endif


int
mdoc_action_pre(struct mdoc *m, const struct mdoc_node *n)
{

	switch (n->type) {
	case (MDOC_ROOT):
		/* FALLTHROUGH */
	case (MDOC_TEXT):
		return(1);
	default:
		break;
	}

	if (NULL == mdoc_actions[n->tok].pre)
		return(1);
	return((*mdoc_actions[n->tok].pre)(m, n));
}


int
mdoc_action_post(struct mdoc *m)
{

	if (MDOC_ACTED & m->last->flags)
		return(1);
	m->last->flags |= MDOC_ACTED;

	switch (m->last->type) {
	case (MDOC_TEXT):
		/* FALLTHROUGH */
	case (MDOC_ROOT):
		return(1);
	default:
		break;
	}

	if (NULL == mdoc_actions[m->last->tok].post)
		return(1);
	return((*mdoc_actions[m->last->tok].post)(m, m->last));
}


static int
concat(struct mdoc *m, const struct mdoc_node *n, 
		char *buf, size_t sz)
{

	for ( ; n; n = n->next) {
		assert(MDOC_TEXT == n->type);
		if (strlcat(buf, n->string, sz) >= sz)
			return(mdoc_nerr(m, n, ETOOLONG));
		if (NULL == n->next)
			continue;
		if (strlcat(buf, " ", sz) >= sz)
			return(mdoc_nerr(m, n, ETOOLONG));
	}

	return(1);
}


static int
post_std(POST_ARGS)
{
	struct mdoc_node	*nn;

	if (n->child)
		return(1);
	
	nn = n;
	m->next = MDOC_NEXT_CHILD;
	assert(m->meta.name);
	if ( ! mdoc_word_alloc(m, n->line, n->pos, m->meta.name))
		return(0);
	m->last = nn;

	return(1);
}


static int
post_nm(POST_ARGS)
{
	char		 buf[64];

	if (m->meta.name)
		return(1);

	buf[0] = 0;
	if ( ! concat(m, n->child, buf, sizeof(buf)))
		return(0);
	if (NULL == (m->meta.name = strdup(buf)))
		return(mdoc_nerr(m, n, EMALLOC));

	return(1);
}


static int
post_lb(POST_ARGS)
{
	const char	*p;
	char		*buf;
	size_t		 sz;

	assert(MDOC_TEXT == n->child->type);
	p = mdoc_a2lib(n->child->string);
	if (NULL == p) {
		sz = strlen(n->child->string) +
			2 + strlen("\\(lqlibrary\\(rq");
		buf = malloc(sz);
		if (NULL == buf)
			return(mdoc_nerr(m, n, EMALLOC));
		(void)snprintf(buf, sz, "library \\(lq%s\\(rq", 
				n->child->string);
		free(n->child->string);
		n->child->string = buf;
		return(1);
	}

	free(n->child->string);
	n->child->string = strdup(p);
	if (NULL == n->child->string)
		return(mdoc_nerr(m, n, EMALLOC));

	return(1);
}


static int
post_st(POST_ARGS)
{
	const char	*p;

	assert(MDOC_TEXT == n->child->type);
	p = mdoc_a2st(n->child->string);
	assert(p);
	free(n->child->string);
	n->child->string = strdup(p);
	if (NULL == n->child->string)
		return(mdoc_nerr(m, n, EMALLOC));

	return(1);
}


static int
post_at(POST_ARGS)
{
	struct mdoc_node	*nn;
	const char		*p;

	if (n->child) {
		assert(MDOC_TEXT == n->child->type);
		p = mdoc_a2att(n->child->string);
		assert(p);
		free(n->child->string);
		n->child->string = strdup(p);
		if (NULL == n->child->string)
			return(mdoc_nerr(m, n, EMALLOC));
		return(1);
	}

	nn = n;
	m->next = MDOC_NEXT_CHILD;

	if ( ! mdoc_word_alloc(m, nn->line, nn->pos, "AT&T UNIX"))
		return(0);
	m->last = nn;

	return(1);
}


static int
post_sh(POST_ARGS)
{
	enum mdoc_sec	 sec;
	char		 buf[64];

	/*
	 * We keep track of the current section /and/ the "named"
	 * section, which is one of the conventional ones, in order to
	 * check ordering.
	 */

	if (MDOC_HEAD != n->type)
		return(1);

	buf[0] = 0;
	if ( ! concat(m, n->child, buf, sizeof(buf)))
		return(0);
	if (SEC_CUSTOM != (sec = mdoc_atosec(buf)))
		m->lastnamed = sec;

	switch ((m->lastsec = sec)) {
	case (SEC_RETURN_VALUES):
		/* FALLTHROUGH */
	case (SEC_ERRORS):
		switch (m->meta.msec) {
		case (2):
			/* FALLTHROUGH */
		case (3):
			/* FALLTHROUGH */
		case (9):
			break;
		default:
			return(mdoc_nwarn(m, n, EBADSEC));
		}
		break;
	default:
		break;
	}
	return(1);
}


static int
post_dt(POST_ARGS)
{
	struct mdoc_node *nn;
	const char	 *cp;
	char		 *ep;
	long		  lval;

	if (m->meta.title)
		free(m->meta.title);
	if (m->meta.vol)
		free(m->meta.vol);
	if (m->meta.arch)
		free(m->meta.arch);

	m->meta.title = m->meta.vol = m->meta.arch = NULL;
	m->meta.msec = 0;

	/* Handles: `.Dt' 
	 *   --> title = unknown, volume = local, msec = 0, arch = NULL
	 */

	if (NULL == (nn = n->child)) {
		if (NULL == (m->meta.title = strdup("unknown")))
			return(mdoc_nerr(m, n, EMALLOC));
		if (NULL == (m->meta.vol = strdup("local")))
			return(mdoc_nerr(m, n, EMALLOC));
		return(post_prol(m, n));
	}

	/* Handles: `.Dt TITLE' 
	 *   --> title = TITLE, volume = local, msec = 0, arch = NULL
	 */

	if (NULL == (m->meta.title = strdup(nn->string)))
		return(mdoc_nerr(m, n, EMALLOC));

	if (NULL == (nn = nn->next)) {
		if (NULL == (m->meta.vol = strdup("local")))
			return(mdoc_nerr(m, n, EMALLOC));
		return(post_prol(m, n));
	}

	/* Handles: `.Dt TITLE SEC'
	 *   --> title = TITLE, volume = SEC is msec ? 
	 *           format(msec) : SEC,
	 *       msec = SEC is msec ? atoi(msec) : 0,
	 *       arch = NULL
	 */

	cp = mdoc_a2msec(nn->string);
	if (cp) {
		if (NULL == (m->meta.vol = strdup(cp)))
			return(mdoc_nerr(m, n, EMALLOC));
		errno = 0;
		lval = strtol(nn->string, &ep, 10);
		if (nn->string[0] != '\0' && *ep == '\0')
			m->meta.msec = (int)lval;
	} else if (NULL == (m->meta.vol = strdup(nn->string)))
		return(mdoc_nerr(m, n, EMALLOC));

	if (NULL == (nn = nn->next))
		return(post_prol(m, n));

	/* Handles: `.Dt TITLE SEC VOL'
	 *   --> title = TITLE, volume = VOL is vol ?
	 *       format(VOL) : 
	 *           VOL is arch ? format(arch) : 
	 *               VOL
	 */

	cp = mdoc_a2vol(nn->string);
	if (cp) {
		free(m->meta.vol);
		if (NULL == (m->meta.vol = strdup(cp)))
			return(mdoc_nerr(m, n, EMALLOC));
	} else {
		cp = mdoc_a2arch(nn->string);
		if (NULL == cp) {
			free(m->meta.vol);
			if (NULL == (m->meta.vol = strdup(nn->string)))
				return(mdoc_nerr(m, n, EMALLOC));
		} else if (NULL == (m->meta.arch = strdup(cp)))
			return(mdoc_nerr(m, n, EMALLOC));
	}	

	/* Ignore any subsequent parameters... */

	return(post_prol(m, n));
}


static int
post_os(POST_ARGS)
{
	char		  buf[64];
	struct utsname	  utsname;

	if (m->meta.os)
		free(m->meta.os);

	buf[0] = 0;
	if ( ! concat(m, n->child, buf, sizeof(buf)))
		return(0);

	if (0 == buf[0]) {
		if (-1 == uname(&utsname))
			return(mdoc_nerr(m, n, EUTSNAME));
		if (strlcat(buf, utsname.sysname, 64) >= 64)
			return(mdoc_nerr(m, n, ETOOLONG));
		if (strlcat(buf, " ", 64) >= 64)
			return(mdoc_nerr(m, n, ETOOLONG));
		if (strlcat(buf, utsname.release, 64) >= 64)
			return(mdoc_nerr(m, n, ETOOLONG));
	}

	if (NULL == (m->meta.os = strdup(buf)))
		return(mdoc_nerr(m, n, EMALLOC));

	return(post_prol(m, n));
}


/*
 * Calculate the -width for a `Bl -tag' list if it hasn't been provided.
 * Uses the first head macro.
 */
static int
post_bl_tagwidth(POST_ARGS)
{
	struct mdoc_node  *nn;
	int		   sz;
	char		   buf[32];

	/*
	 * Use the text width, if a text node, or the default macro
	 * width if a macro.
	 */

	nn = n->body->child;
	if (nn) {
		assert(MDOC_BLOCK == nn->type);
		assert(MDOC_It == nn->tok);
		nn = nn->head->child;
	}

	sz = 10; /* Default size. */

	if (nn) {
		if (MDOC_TEXT != nn->type) {
			if (0 == (sz = (int)mdoc_macro2len(nn->tok)))
				if ( ! mdoc_nwarn(m, n, ENOWIDTH))
					return(0);
		} else
			sz = (int)strlen(nn->string) + 1;
	} 

	if (-1 == snprintf(buf, sizeof(buf), "%dn", sz))
		return(mdoc_nerr(m, n, ENUMFMT));

	/*
	 * We have to dynamically add this to the macro's argument list.
	 * We're guaranteed that a MDOC_Width doesn't already exist.
	 */

	nn = n;
	assert(nn->args);
	sz = (int)(nn->args->argc)++;

	nn->args->argv = realloc(nn->args->argv, 
			nn->args->argc * sizeof(struct mdoc_argv));

	if (NULL == nn->args->argv)
		return(mdoc_nerr(m, n, EMALLOC));

	nn->args->argv[sz].arg = MDOC_Width;
	nn->args->argv[sz].line = n->line;
	nn->args->argv[sz].pos = n->pos;
	nn->args->argv[sz].sz = 1;
	nn->args->argv[sz].value = calloc(1, sizeof(char *));

	if (NULL == nn->args->argv[sz].value)
		return(mdoc_nerr(m, n, EMALLOC));
	if (NULL == (nn->args->argv[sz].value[0] = strdup(buf)))
		return(mdoc_nerr(m, n, EMALLOC));

	return(1);
}


static int
post_bl_width(POST_ARGS)
{
	size_t		  width;
	int		  i, tok;
	char		  buf[32];
	char		 *p;

	if (NULL == n->args)
		return(1);

	for (i = 0; i < (int)n->args->argc; i++)
		if (MDOC_Width == n->args->argv[i].arg)
			break;

	if (i == (int)n->args->argc)
		return(1);
	p = n->args->argv[i].value[0];

	/*
	 * If the value to -width is a macro, then we re-write it to be
	 * the macro's width as set in share/tmac/mdoc/doc-common.
	 */

	if (0 == strcmp(p, "Ds"))
		width = 6;
	else if (MDOC_MAX == (tok = mdoc_hash_find(p)))
		return(1);
	else if (0 == (width = mdoc_macro2len(tok))) 
		return(mdoc_nwarn(m, n, ENOWIDTH));

	/* The value already exists: free and reallocate it. */

	if (-1 == snprintf(buf, sizeof(buf), "%zun", width))
		return(mdoc_nerr(m, n, ENUMFMT));

	free(n->args->argv[i].value[0]);
	n->args->argv[i].value[0] = strdup(buf);
	if (NULL == n->args->argv[i].value[0])
		return(mdoc_nerr(m, n, EMALLOC));

	return(1);
}


/* ARGSUSED */
static int
post_bl_head(POST_ARGS)
{
	int			 i, c;
	struct mdoc_node	*np, *nn, *nnp;

	if (NULL == n->child)
		return(1);

	np = n->parent;
	assert(np->args);

	for (c = 0; c < (int)np->args->argc; c++) 
		if (MDOC_Column == np->args->argv[c].arg)
			break;

	/* Only process -column. */

	if (c == (int)np->args->argc)
		return(1);
	
	assert(0 == np->args->argv[c].sz);

	/*
	 * Accomodate for new-style groff column syntax.  Shuffle the
	 * child nodes, all of which must be TEXT, as arguments for the
	 * column field.  Then, delete the head children.
	 */

	np->args->argv[c].sz = (size_t)n->nchild;
	np->args->argv[c].value = malloc
		((size_t)n->nchild * sizeof(char *));

	for (i = 0, nn = n->child; nn; i++) {
		np->args->argv[c].value[i] = nn->string;
		nn->string = NULL;
		nnp = nn;
		nn = nn->next;
		mdoc_node_free(nnp);
	}

	n->nchild = 0;
	n->child = NULL;

	return(1);
}


static int
post_bl(POST_ARGS)
{
	int		  i, r, len;

	if (MDOC_HEAD == n->type)
		return(post_bl_head(m, n));
	if (MDOC_BLOCK != n->type)
		return(1);

	/*
	 * These are fairly complicated, so we've broken them into two
	 * functions.  post_bl_tagwidth() is called when a -tag is
	 * specified, but no -width (it must be guessed).  The second
	 * when a -width is specified (macro indicators must be
	 * rewritten into real lengths).
	 */

	len = (int)(n->args ? n->args->argc : 0);

	for (r = i = 0; i < len; i++) {
		if (MDOC_Tag == n->args->argv[i].arg)
			r |= 1 << 0;
		if (MDOC_Width == n->args->argv[i].arg)
			r |= 1 << 1;
	}

	if (r & (1 << 0) && ! (r & (1 << 1))) {
		if ( ! post_bl_tagwidth(m, n))
			return(0);
	} else if (r & (1 << 1))
		if ( ! post_bl_width(m, n))
			return(0);

	return(1);
}


static int
post_tilde(POST_ARGS)
{
	struct mdoc_node *np;

	if (n->child)
		return(1);
	
	np = n;
	m->next = MDOC_NEXT_CHILD;

	/* XXX: not documented for `Lk'. */
	if ( ! mdoc_word_alloc(m, n->line, n->pos, "~"))
		return(0);
	m->last = np;

	return(1);
}


static int
post_ar(POST_ARGS)
{
	struct mdoc_node *np;

	if (n->child)
		return(1);
	
	np = n;
	m->next = MDOC_NEXT_CHILD;
	if ( ! mdoc_word_alloc(m, n->line, n->pos, "file"))
		return(0);
	if ( ! mdoc_word_alloc(m, n->line, n->pos, "..."))
		return(0);
	m->last = np;

	return(1);
}


static int
post_dd(POST_ARGS)
{
	char		  buf[64];

	buf[0] = 0;
	if ( ! concat(m, n->child, buf, sizeof(buf)))
		return(0);

	if (0 == (m->meta.date = mdoc_atotime(buf))) {
		if ( ! mdoc_nwarn(m, n, EBADDATE))
			return(0);
		m->meta.date = time(NULL);
	}

	return(post_prol(m, n));
}


static int
post_prol(POST_ARGS)
{
	struct mdoc_node *np;

	/* Remove prologue macros from AST.  */

	if (n->parent->child == n)
		n->parent->child = n->prev;
	if (n->prev)
		n->prev->next = NULL;

	np = n;
	assert(NULL == n->next);

	if (n->prev) {
		m->last = n->prev;
		m->next = MDOC_NEXT_SIBLING;
	} else {
		m->last = n->parent;
		m->next = MDOC_NEXT_CHILD;
	}

	mdoc_node_freelist(np);

	if (m->meta.title && m->meta.date && m->meta.os)
		m->flags |= MDOC_PBODY;

	return(1);
}


static int
pre_dl(PRE_ARGS)
{

	if (MDOC_BODY == n->type)
		m->flags |= MDOC_LITERAL;
	return(1);
}


static int
pre_offset(PRE_ARGS)
{
	int		 i;

	/* 
	 * Make sure that an empty offset produces an 8n length space as
	 * stipulated by mdoc.samples. 
	 */

	assert(n->args);
	for (i = 0; i < (int)n->args->argc; i++) {
		if (MDOC_Offset != n->args->argv[i].arg) 
			continue;
		if (n->args->argv[i].sz)
			break;
		assert(1 == n->args->refcnt);
		/* If no value set, length of <string>. */
		n->args->argv[i].value = 
		calloc(1, sizeof(char *));
		if (NULL == n->args->argv[i].value)
			return(mdoc_nerr(m, n, EMALLOC));
		n->args->argv[i].sz++;
		n->args->argv[i].value[0] = strdup("8n");
		if (NULL == n->args->argv[i].value[0])
			return(mdoc_nerr(m, n, EMALLOC));
		break;
	}

	return(1);
}


static int
pre_bl(PRE_ARGS)
{

	return(MDOC_BLOCK == n->type ? pre_offset(m, n) : 1);
}


static int
pre_bd(PRE_ARGS)
{
	int		 i;

	if (MDOC_BLOCK == n->type)
		return(pre_offset(m, n));
	if (MDOC_BODY != n->type)
		return(1);

	/* Enter literal context if `Bd -literal' or `-unfilled'. */

	for (n = n->parent, i = 0; i < (int)n->args->argc; i++)
		if (MDOC_Literal == n->args->argv[i].arg)
			m->flags |= MDOC_LITERAL;
		else if (MDOC_Unfilled == n->args->argv[i].arg)
			m->flags |= MDOC_LITERAL;

	return(1);
}


static int
post_display(POST_ARGS)
{

	if (MDOC_BODY == n->type)
		m->flags &= ~MDOC_LITERAL;
	return(1);
}