root/usr/src/cmd/mandoc/mdoc_validate.c
/* $Id: mdoc_validate.c,v 1.389 2021/07/18 11:41:23 schwarze Exp $ */
/*
 * Copyright (c) 2010-2020 Ingo Schwarze <schwarze@openbsd.org>
 * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
 * Copyright (c) 2010 Joerg Sonnenberger <joerg@netbsd.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.
 *
 * Validation module for mdoc(7) syntax trees used by mandoc(1).
 */
#include "config.h"

#include <sys/types.h>
#ifndef OSNAME
#include <sys/utsname.h>
#endif

#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "mandoc_aux.h"
#include "mandoc.h"
#include "mandoc_xr.h"
#include "roff.h"
#include "mdoc.h"
#include "libmandoc.h"
#include "roff_int.h"
#include "libmdoc.h"
#include "tag.h"

/* FIXME: .Bl -diag can't have non-text children in HEAD. */

#define POST_ARGS struct roff_man *mdoc

enum    check_ineq {
        CHECK_LT,
        CHECK_GT,
        CHECK_EQ
};

typedef void    (*v_post)(POST_ARGS);

static  int      build_list(struct roff_man *, int);
static  void     check_argv(struct roff_man *,
                        struct roff_node *, struct mdoc_argv *);
static  void     check_args(struct roff_man *, struct roff_node *);
static  void     check_text(struct roff_man *, int, int, char *);
static  void     check_text_em(struct roff_man *, int, int, char *);
static  void     check_toptext(struct roff_man *, int, int, const char *);
static  int      child_an(const struct roff_node *);
static  size_t          macro2len(enum roff_tok);
static  void     rewrite_macro2len(struct roff_man *, char **);
static  int      similar(const char *, const char *);

static  void     post_abort(POST_ARGS) __attribute__((__noreturn__));
static  void     post_an(POST_ARGS);
static  void     post_an_norm(POST_ARGS);
static  void     post_at(POST_ARGS);
static  void     post_bd(POST_ARGS);
static  void     post_bf(POST_ARGS);
static  void     post_bk(POST_ARGS);
static  void     post_bl(POST_ARGS);
static  void     post_bl_block(POST_ARGS);
static  void     post_bl_head(POST_ARGS);
static  void     post_bl_norm(POST_ARGS);
static  void     post_bx(POST_ARGS);
static  void     post_defaults(POST_ARGS);
static  void     post_display(POST_ARGS);
static  void     post_dd(POST_ARGS);
static  void     post_delim(POST_ARGS);
static  void     post_delim_nb(POST_ARGS);
static  void     post_dt(POST_ARGS);
static  void     post_em(POST_ARGS);
static  void     post_en(POST_ARGS);
static  void     post_er(POST_ARGS);
static  void     post_es(POST_ARGS);
static  void     post_eoln(POST_ARGS);
static  void     post_ex(POST_ARGS);
static  void     post_fa(POST_ARGS);
static  void     post_fl(POST_ARGS);
static  void     post_fn(POST_ARGS);
static  void     post_fname(POST_ARGS);
static  void     post_fo(POST_ARGS);
static  void     post_hyph(POST_ARGS);
static  void     post_it(POST_ARGS);
static  void     post_lb(POST_ARGS);
static  void     post_nd(POST_ARGS);
static  void     post_nm(POST_ARGS);
static  void     post_ns(POST_ARGS);
static  void     post_obsolete(POST_ARGS);
static  void     post_os(POST_ARGS);
static  void     post_par(POST_ARGS);
static  void     post_prevpar(POST_ARGS);
static  void     post_root(POST_ARGS);
static  void     post_rs(POST_ARGS);
static  void     post_rv(POST_ARGS);
static  void     post_section(POST_ARGS);
static  void     post_sh(POST_ARGS);
static  void     post_sh_head(POST_ARGS);
static  void     post_sh_name(POST_ARGS);
static  void     post_sh_see_also(POST_ARGS);
static  void     post_sh_authors(POST_ARGS);
static  void     post_sm(POST_ARGS);
static  void     post_st(POST_ARGS);
static  void     post_std(POST_ARGS);
static  void     post_sx(POST_ARGS);
static  void     post_tag(POST_ARGS);
static  void     post_tg(POST_ARGS);
static  void     post_useless(POST_ARGS);
static  void     post_xr(POST_ARGS);
static  void     post_xx(POST_ARGS);

static  const v_post mdoc_valids[MDOC_MAX - MDOC_Dd] = {
        post_dd,        /* Dd */
        post_dt,        /* Dt */
        post_os,        /* Os */
        post_sh,        /* Sh */
        post_section,   /* Ss */
        post_par,       /* Pp */
        post_display,   /* D1 */
        post_display,   /* Dl */
        post_display,   /* Bd */
        NULL,           /* Ed */
        post_bl,        /* Bl */
        NULL,           /* El */
        post_it,        /* It */
        post_delim_nb,  /* Ad */
        post_an,        /* An */
        NULL,           /* Ap */
        post_defaults,  /* Ar */
        NULL,           /* Cd */
        post_tag,       /* Cm */
        post_tag,       /* Dv */
        post_er,        /* Er */
        post_tag,       /* Ev */
        post_ex,        /* Ex */
        post_fa,        /* Fa */
        NULL,           /* Fd */
        post_fl,        /* Fl */
        post_fn,        /* Fn */
        post_delim_nb,  /* Ft */
        post_tag,       /* Ic */
        post_delim_nb,  /* In */
        post_tag,       /* Li */
        post_nd,        /* Nd */
        post_nm,        /* Nm */
        post_delim_nb,  /* Op */
        post_abort,     /* Ot */
        post_defaults,  /* Pa */
        post_rv,        /* Rv */
        post_st,        /* St */
        post_tag,       /* Va */
        post_delim_nb,  /* Vt */
        post_xr,        /* Xr */
        NULL,           /* %A */
        post_hyph,      /* %B */ /* FIXME: can be used outside Rs/Re. */
        NULL,           /* %D */
        NULL,           /* %I */
        NULL,           /* %J */
        post_hyph,      /* %N */
        post_hyph,      /* %O */
        NULL,           /* %P */
        post_hyph,      /* %R */
        post_hyph,      /* %T */ /* FIXME: can be used outside Rs/Re. */
        NULL,           /* %V */
        NULL,           /* Ac */
        NULL,           /* Ao */
        post_delim_nb,  /* Aq */
        post_at,        /* At */
        NULL,           /* Bc */
        post_bf,        /* Bf */
        NULL,           /* Bo */
        NULL,           /* Bq */
        post_xx,        /* Bsx */
        post_bx,        /* Bx */
        post_obsolete,  /* Db */
        NULL,           /* Dc */
        NULL,           /* Do */
        NULL,           /* Dq */
        NULL,           /* Ec */
        NULL,           /* Ef */
        post_em,        /* Em */
        NULL,           /* Eo */
        post_xx,        /* Fx */
        post_tag,       /* Ms */
        post_tag,       /* No */
        post_ns,        /* Ns */
        post_xx,        /* Nx */
        post_xx,        /* Ox */
        NULL,           /* Pc */
        NULL,           /* Pf */
        NULL,           /* Po */
        post_delim_nb,  /* Pq */
        NULL,           /* Qc */
        post_delim_nb,  /* Ql */
        NULL,           /* Qo */
        post_delim_nb,  /* Qq */
        NULL,           /* Re */
        post_rs,        /* Rs */
        NULL,           /* Sc */
        NULL,           /* So */
        post_delim_nb,  /* Sq */
        post_sm,        /* Sm */
        post_sx,        /* Sx */
        post_em,        /* Sy */
        post_useless,   /* Tn */
        post_xx,        /* Ux */
        NULL,           /* Xc */
        NULL,           /* Xo */
        post_fo,        /* Fo */
        NULL,           /* Fc */
        NULL,           /* Oo */
        NULL,           /* Oc */
        post_bk,        /* Bk */
        NULL,           /* Ek */
        post_eoln,      /* Bt */
        post_obsolete,  /* Hf */
        post_obsolete,  /* Fr */
        post_eoln,      /* Ud */
        post_lb,        /* Lb */
        post_abort,     /* Lp */
        post_delim_nb,  /* Lk */
        post_defaults,  /* Mt */
        post_delim_nb,  /* Brq */
        NULL,           /* Bro */
        NULL,           /* Brc */
        NULL,           /* %C */
        post_es,        /* Es */
        post_en,        /* En */
        post_xx,        /* Dx */
        NULL,           /* %Q */
        NULL,           /* %U */
        NULL,           /* Ta */
        post_tg,        /* Tg */
};

#define RSORD_MAX 14 /* Number of `Rs' blocks. */

static  const enum roff_tok rsord[RSORD_MAX] = {
        MDOC__A,
        MDOC__T,
        MDOC__B,
        MDOC__I,
        MDOC__J,
        MDOC__R,
        MDOC__N,
        MDOC__V,
        MDOC__U,
        MDOC__P,
        MDOC__Q,
        MDOC__C,
        MDOC__D,
        MDOC__O
};

static  const char * const secnames[SEC__MAX] = {
        NULL,
        "NAME",
        "LIBRARY",
        "SYNOPSIS",
        "DESCRIPTION",
        "CONTEXT",
        "IMPLEMENTATION NOTES",
        "RETURN VALUES",
        "ENVIRONMENT",
        "FILES",
        "EXIT STATUS",
        "EXAMPLES",
        "DIAGNOSTICS",
        "COMPATIBILITY",
        "ERRORS",
        "SEE ALSO",
        "STANDARDS",
        "HISTORY",
        "AUTHORS",
        "CAVEATS",
        "BUGS",
        "SECURITY CONSIDERATIONS",
        NULL
};

static  int       fn_prio = TAG_STRONG;


/* Validate the subtree rooted at mdoc->last. */
void
mdoc_validate(struct roff_man *mdoc)
{
        struct roff_node *n, *np;
        const v_post *p;

        /*
         * Translate obsolete macros to modern macros first
         * such that later code does not need to look
         * for the obsolete versions.
         */

        n = mdoc->last;
        switch (n->tok) {
        case MDOC_Lp:
                n->tok = MDOC_Pp;
                break;
        case MDOC_Ot:
                post_obsolete(mdoc);
                n->tok = MDOC_Ft;
                break;
        default:
                break;
        }

        /*
         * Iterate over all children, recursing into each one
         * in turn, depth-first.
         */

        mdoc->last = mdoc->last->child;
        while (mdoc->last != NULL) {
                mdoc_validate(mdoc);
                if (mdoc->last == n)
                        mdoc->last = mdoc->last->child;
                else
                        mdoc->last = mdoc->last->next;
        }

        /* Finally validate the macro itself. */

        mdoc->last = n;
        mdoc->next = ROFF_NEXT_SIBLING;
        switch (n->type) {
        case ROFFT_TEXT:
                np = n->parent;
                if (n->sec != SEC_SYNOPSIS ||
                    (np->tok != MDOC_Cd && np->tok != MDOC_Fd))
                        check_text(mdoc, n->line, n->pos, n->string);
                if ((n->flags & NODE_NOFILL) == 0 &&
                    (np->tok != MDOC_It || np->type != ROFFT_HEAD ||
                     np->parent->parent->norm->Bl.type != LIST_diag))
                        check_text_em(mdoc, n->line, n->pos, n->string);
                if (np->tok == MDOC_It || (np->type == ROFFT_BODY &&
                    (np->tok == MDOC_Sh || np->tok == MDOC_Ss)))
                        check_toptext(mdoc, n->line, n->pos, n->string);
                break;
        case ROFFT_COMMENT:
        case ROFFT_EQN:
        case ROFFT_TBL:
                break;
        case ROFFT_ROOT:
                post_root(mdoc);
                break;
        default:
                check_args(mdoc, mdoc->last);

                /*
                 * Closing delimiters are not special at the
                 * beginning of a block, opening delimiters
                 * are not special at the end.
                 */

                if (n->child != NULL)
                        n->child->flags &= ~NODE_DELIMC;
                if (n->last != NULL)
                        n->last->flags &= ~NODE_DELIMO;

                /* Call the macro's postprocessor. */

                if (n->tok < ROFF_MAX) {
                        roff_validate(mdoc);
                        break;
                }

                assert(n->tok >= MDOC_Dd && n->tok < MDOC_MAX);
                p = mdoc_valids + (n->tok - MDOC_Dd);
                if (*p)
                        (*p)(mdoc);
                if (mdoc->last == n)
                        mdoc_state(mdoc, n);
                break;
        }
}

static void
check_args(struct roff_man *mdoc, struct roff_node *n)
{
        int              i;

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

        assert(n->args->argc);
        for (i = 0; i < (int)n->args->argc; i++)
                check_argv(mdoc, n, &n->args->argv[i]);
}

static void
check_argv(struct roff_man *mdoc, struct roff_node *n, struct mdoc_argv *v)
{
        int              i;

        for (i = 0; i < (int)v->sz; i++)
                check_text(mdoc, v->line, v->pos, v->value[i]);
}

static void
check_text(struct roff_man *mdoc, int ln, int pos, char *p)
{
        char            *cp;

        if (mdoc->last->flags & NODE_NOFILL)
                return;

        for (cp = p; NULL != (p = strchr(p, '\t')); p++)
                mandoc_msg(MANDOCERR_FI_TAB, ln, pos + (int)(p - cp), NULL);
}

static void
check_text_em(struct roff_man *mdoc, int ln, int pos, char *p)
{
        const struct roff_node  *np, *nn;
        char                    *cp;

        np = mdoc->last->prev;
        nn = mdoc->last->next;

        /* Look for em-dashes wrongly encoded as "--". */

        for (cp = p; *cp != '\0'; cp++) {
                if (cp[0] != '-' || cp[1] != '-')
                        continue;
                cp++;

                /* Skip input sequences of more than two '-'. */

                if (cp[1] == '-') {
                        while (cp[1] == '-')
                                cp++;
                        continue;
                }

                /* Skip "--" directly attached to something else. */

                if ((cp - p > 1 && cp[-2] != ' ') ||
                    (cp[1] != '\0' && cp[1] != ' '))
                        continue;

                /* Require a letter right before or right afterwards. */

                if ((cp - p > 2 ?
                     isalpha((unsigned char)cp[-3]) :
                     np != NULL &&
                     np->type == ROFFT_TEXT &&
                     *np->string != '\0' &&
                     isalpha((unsigned char)np->string[
                       strlen(np->string) - 1])) ||
                    (cp[1] != '\0' && cp[2] != '\0' ?
                     isalpha((unsigned char)cp[2]) :
                     nn != NULL &&
                     nn->type == ROFFT_TEXT &&
                     isalpha((unsigned char)*nn->string))) {
                        mandoc_msg(MANDOCERR_DASHDASH,
                            ln, pos + (int)(cp - p) - 1, NULL);
                        break;
                }
        }
}

static void
check_toptext(struct roff_man *mdoc, int ln, int pos, const char *p)
{
        const char      *cp, *cpr;

        if (*p == '\0')
                return;

        if ((cp = strstr(p, "OpenBSD")) != NULL)
                mandoc_msg(MANDOCERR_BX, ln, pos + (int)(cp - p), "Ox");
        if ((cp = strstr(p, "NetBSD")) != NULL)
                mandoc_msg(MANDOCERR_BX, ln, pos + (int)(cp - p), "Nx");
        if ((cp = strstr(p, "FreeBSD")) != NULL)
                mandoc_msg(MANDOCERR_BX, ln, pos + (int)(cp - p), "Fx");
        if ((cp = strstr(p, "DragonFly")) != NULL)
                mandoc_msg(MANDOCERR_BX, ln, pos + (int)(cp - p), "Dx");

        cp = p;
        while ((cp = strstr(cp + 1, "()")) != NULL) {
                for (cpr = cp - 1; cpr >= p; cpr--)
                        if (*cpr != '_' && !isalnum((unsigned char)*cpr))
                                break;
                if ((cpr < p || *cpr == ' ') && cpr + 1 < cp) {
                        cpr++;
                        mandoc_msg(MANDOCERR_FUNC, ln, pos + (int)(cpr - p),
                            "%.*s()", (int)(cp - cpr), cpr);
                }
        }
}

static void
post_abort(POST_ARGS)
{
        abort();
}

static void
post_delim(POST_ARGS)
{
        const struct roff_node  *nch;
        const char              *lc;
        enum mdelim              delim;
        enum roff_tok            tok;

        tok = mdoc->last->tok;
        nch = mdoc->last->last;
        if (nch == NULL || nch->type != ROFFT_TEXT)
                return;
        lc = strchr(nch->string, '\0') - 1;
        if (lc < nch->string)
                return;
        delim = mdoc_isdelim(lc);
        if (delim == DELIM_NONE || delim == DELIM_OPEN)
                return;
        if (*lc == ')' && (tok == MDOC_Nd || tok == MDOC_Sh ||
            tok == MDOC_Ss || tok == MDOC_Fo))
                return;

        mandoc_msg(MANDOCERR_DELIM, nch->line,
            nch->pos + (int)(lc - nch->string), "%s%s %s", roff_name[tok],
            nch == mdoc->last->child ? "" : " ...", nch->string);
}

static void
post_delim_nb(POST_ARGS)
{
        const struct roff_node  *nch;
        const char              *lc, *cp;
        int                      nw;
        enum mdelim              delim;
        enum roff_tok            tok;

        /*
         * Find candidates: at least two bytes,
         * the last one a closing or middle delimiter.
         */

        tok = mdoc->last->tok;
        nch = mdoc->last->last;
        if (nch == NULL || nch->type != ROFFT_TEXT)
                return;
        lc = strchr(nch->string, '\0') - 1;
        if (lc <= nch->string)
                return;
        delim = mdoc_isdelim(lc);
        if (delim == DELIM_NONE || delim == DELIM_OPEN)
                return;

        /*
         * Reduce false positives by allowing various cases.
         */

        /* Escaped delimiters. */
        if (lc > nch->string + 1 && lc[-2] == '\\' &&
            (lc[-1] == '&' || lc[-1] == 'e'))
                return;

        /* Specific byte sequences. */
        switch (*lc) {
        case ')':
                for (cp = lc; cp >= nch->string; cp--)
                        if (*cp == '(')
                                return;
                break;
        case '.':
                if (lc > nch->string + 1 && lc[-2] == '.' && lc[-1] == '.')
                        return;
                if (lc[-1] == '.')
                        return;
                break;
        case ';':
                if (tok == MDOC_Vt)
                        return;
                break;
        case '?':
                if (lc[-1] == '?')
                        return;
                break;
        case ']':
                for (cp = lc; cp >= nch->string; cp--)
                        if (*cp == '[')
                                return;
                break;
        case '|':
                if (lc == nch->string + 1 && lc[-1] == '|')
                        return;
        default:
                break;
        }

        /* Exactly two non-alphanumeric bytes. */
        if (lc == nch->string + 1 && !isalnum((unsigned char)lc[-1]))
                return;

        /* At least three alphabetic words with a sentence ending. */
        if (strchr("!.:?", *lc) != NULL && (tok == MDOC_Em ||
            tok == MDOC_Li || tok == MDOC_Pq || tok == MDOC_Sy)) {
                nw = 0;
                for (cp = lc - 1; cp >= nch->string; cp--) {
                        if (*cp == ' ') {
                                nw++;
                                if (cp > nch->string && cp[-1] == ',')
                                        cp--;
                        } else if (isalpha((unsigned int)*cp)) {
                                if (nw > 1)
                                        return;
                        } else
                                break;
                }
        }

        mandoc_msg(MANDOCERR_DELIM_NB, nch->line,
            nch->pos + (int)(lc - nch->string), "%s%s %s", roff_name[tok],
            nch == mdoc->last->child ? "" : " ...", nch->string);
}

static void
post_bl_norm(POST_ARGS)
{
        struct roff_node *n;
        struct mdoc_argv *argv, *wa;
        int               i;
        enum mdocargt     mdoclt;
        enum mdoc_list    lt;

        n = mdoc->last->parent;
        n->norm->Bl.type = LIST__NONE;

        /*
         * First figure out which kind of list to use: bind ourselves to
         * the first mentioned list type and warn about any remaining
         * ones.  If we find no list type, we default to LIST_item.
         */

        wa = (n->args == NULL) ? NULL : n->args->argv;
        mdoclt = MDOC_ARG_MAX;
        for (i = 0; n->args && i < (int)n->args->argc; i++) {
                argv = n->args->argv + i;
                lt = LIST__NONE;
                switch (argv->arg) {
                /* Set list types. */
                case MDOC_Bullet:
                        lt = LIST_bullet;
                        break;
                case MDOC_Dash:
                        lt = LIST_dash;
                        break;
                case MDOC_Enum:
                        lt = LIST_enum;
                        break;
                case MDOC_Hyphen:
                        lt = LIST_hyphen;
                        break;
                case MDOC_Item:
                        lt = LIST_item;
                        break;
                case MDOC_Tag:
                        lt = LIST_tag;
                        break;
                case MDOC_Diag:
                        lt = LIST_diag;
                        break;
                case MDOC_Hang:
                        lt = LIST_hang;
                        break;
                case MDOC_Ohang:
                        lt = LIST_ohang;
                        break;
                case MDOC_Inset:
                        lt = LIST_inset;
                        break;
                case MDOC_Column:
                        lt = LIST_column;
                        break;
                /* Set list arguments. */
                case MDOC_Compact:
                        if (n->norm->Bl.comp)
                                mandoc_msg(MANDOCERR_ARG_REP,
                                    argv->line, argv->pos, "Bl -compact");
                        n->norm->Bl.comp = 1;
                        break;
                case MDOC_Width:
                        wa = argv;
                        if (0 == argv->sz) {
                                mandoc_msg(MANDOCERR_ARG_EMPTY,
                                    argv->line, argv->pos, "Bl -width");
                                n->norm->Bl.width = "0n";
                                break;
                        }
                        if (NULL != n->norm->Bl.width)
                                mandoc_msg(MANDOCERR_ARG_REP,
                                    argv->line, argv->pos,
                                    "Bl -width %s", argv->value[0]);
                        rewrite_macro2len(mdoc, argv->value);
                        n->norm->Bl.width = argv->value[0];
                        break;
                case MDOC_Offset:
                        if (0 == argv->sz) {
                                mandoc_msg(MANDOCERR_ARG_EMPTY,
                                    argv->line, argv->pos, "Bl -offset");
                                break;
                        }
                        if (NULL != n->norm->Bl.offs)
                                mandoc_msg(MANDOCERR_ARG_REP,
                                    argv->line, argv->pos,
                                    "Bl -offset %s", argv->value[0]);
                        rewrite_macro2len(mdoc, argv->value);
                        n->norm->Bl.offs = argv->value[0];
                        break;
                default:
                        continue;
                }
                if (LIST__NONE == lt)
                        continue;
                mdoclt = argv->arg;

                /* Check: multiple list types. */

                if (LIST__NONE != n->norm->Bl.type) {
                        mandoc_msg(MANDOCERR_BL_REP, n->line, n->pos,
                            "Bl -%s", mdoc_argnames[argv->arg]);
                        continue;
                }

                /* The list type should come first. */

                if (n->norm->Bl.width ||
                    n->norm->Bl.offs ||
                    n->norm->Bl.comp)
                        mandoc_msg(MANDOCERR_BL_LATETYPE,
                            n->line, n->pos, "Bl -%s",
                            mdoc_argnames[n->args->argv[0].arg]);

                n->norm->Bl.type = lt;
                if (LIST_column == lt) {
                        n->norm->Bl.ncols = argv->sz;
                        n->norm->Bl.cols = (void *)argv->value;
                }
        }

        /* Allow lists to default to LIST_item. */

        if (LIST__NONE == n->norm->Bl.type) {
                mandoc_msg(MANDOCERR_BL_NOTYPE, n->line, n->pos, "Bl");
                n->norm->Bl.type = LIST_item;
                mdoclt = MDOC_Item;
        }

        /*
         * Validate the width field.  Some list types don't need width
         * types and should be warned about them.  Others should have it
         * and must also be warned.  Yet others have a default and need
         * no warning.
         */

        switch (n->norm->Bl.type) {
        case LIST_tag:
                if (n->norm->Bl.width == NULL)
                        mandoc_msg(MANDOCERR_BL_NOWIDTH,
                            n->line, n->pos, "Bl -tag");
                break;
        case LIST_column:
        case LIST_diag:
        case LIST_ohang:
        case LIST_inset:
        case LIST_item:
                if (n->norm->Bl.width != NULL)
                        mandoc_msg(MANDOCERR_BL_SKIPW, wa->line, wa->pos,
                            "Bl -%s", mdoc_argnames[mdoclt]);
                n->norm->Bl.width = NULL;
                break;
        case LIST_bullet:
        case LIST_dash:
        case LIST_hyphen:
                if (n->norm->Bl.width == NULL)
                        n->norm->Bl.width = "2n";
                break;
        case LIST_enum:
                if (n->norm->Bl.width == NULL)
                        n->norm->Bl.width = "3n";
                break;
        default:
                break;
        }
}

static void
post_bd(POST_ARGS)
{
        struct roff_node *n;
        struct mdoc_argv *argv;
        int               i;
        enum mdoc_disp    dt;

        n = mdoc->last;
        for (i = 0; n->args && i < (int)n->args->argc; i++) {
                argv = n->args->argv + i;
                dt = DISP__NONE;

                switch (argv->arg) {
                case MDOC_Centred:
                        dt = DISP_centered;
                        break;
                case MDOC_Ragged:
                        dt = DISP_ragged;
                        break;
                case MDOC_Unfilled:
                        dt = DISP_unfilled;
                        break;
                case MDOC_Filled:
                        dt = DISP_filled;
                        break;
                case MDOC_Literal:
                        dt = DISP_literal;
                        break;
                case MDOC_File:
                        mandoc_msg(MANDOCERR_BD_FILE, n->line, n->pos, NULL);
                        break;
                case MDOC_Offset:
                        if (0 == argv->sz) {
                                mandoc_msg(MANDOCERR_ARG_EMPTY,
                                    argv->line, argv->pos, "Bd -offset");
                                break;
                        }
                        if (NULL != n->norm->Bd.offs)
                                mandoc_msg(MANDOCERR_ARG_REP,
                                    argv->line, argv->pos,
                                    "Bd -offset %s", argv->value[0]);
                        rewrite_macro2len(mdoc, argv->value);
                        n->norm->Bd.offs = argv->value[0];
                        break;
                case MDOC_Compact:
                        if (n->norm->Bd.comp)
                                mandoc_msg(MANDOCERR_ARG_REP,
                                    argv->line, argv->pos, "Bd -compact");
                        n->norm->Bd.comp = 1;
                        break;
                default:
                        abort();
                }
                if (DISP__NONE == dt)
                        continue;

                if (DISP__NONE == n->norm->Bd.type)
                        n->norm->Bd.type = dt;
                else
                        mandoc_msg(MANDOCERR_BD_REP, n->line, n->pos,
                            "Bd -%s", mdoc_argnames[argv->arg]);
        }

        if (DISP__NONE == n->norm->Bd.type) {
                mandoc_msg(MANDOCERR_BD_NOTYPE, n->line, n->pos, "Bd");
                n->norm->Bd.type = DISP_ragged;
        }
}

/*
 * Stand-alone line macros.
 */

static void
post_an_norm(POST_ARGS)
{
        struct roff_node *n;
        struct mdoc_argv *argv;
        size_t   i;

        n = mdoc->last;
        if (n->args == NULL)
                return;

        for (i = 1; i < n->args->argc; i++) {
                argv = n->args->argv + i;
                mandoc_msg(MANDOCERR_AN_REP, argv->line, argv->pos,
                    "An -%s", mdoc_argnames[argv->arg]);
        }

        argv = n->args->argv;
        if (argv->arg == MDOC_Split)
                n->norm->An.auth = AUTH_split;
        else if (argv->arg == MDOC_Nosplit)
                n->norm->An.auth = AUTH_nosplit;
        else
                abort();
}

static void
post_eoln(POST_ARGS)
{
        struct roff_node        *n;

        post_useless(mdoc);
        n = mdoc->last;
        if (n->child != NULL)
                mandoc_msg(MANDOCERR_ARG_SKIP, n->line,
                    n->pos, "%s %s", roff_name[n->tok], n->child->string);

        while (n->child != NULL)
                roff_node_delete(mdoc, n->child);

        roff_word_alloc(mdoc, n->line, n->pos, n->tok == MDOC_Bt ?
            "is currently in beta test." : "currently under development.");
        mdoc->last->flags |= NODE_EOS | NODE_NOSRC;
        mdoc->last = n;
}

static int
build_list(struct roff_man *mdoc, int tok)
{
        struct roff_node        *n;
        int                      ic;

        n = mdoc->last->next;
        for (ic = 1;; ic++) {
                roff_elem_alloc(mdoc, n->line, n->pos, tok);
                mdoc->last->flags |= NODE_NOSRC;
                roff_node_relink(mdoc, n);
                n = mdoc->last = mdoc->last->parent;
                mdoc->next = ROFF_NEXT_SIBLING;
                if (n->next == NULL)
                        return ic;
                if (ic > 1 || n->next->next != NULL) {
                        roff_word_alloc(mdoc, n->line, n->pos, ",");
                        mdoc->last->flags |= NODE_DELIMC | NODE_NOSRC;
                }
                n = mdoc->last->next;
                if (n->next == NULL) {
                        roff_word_alloc(mdoc, n->line, n->pos, "and");
                        mdoc->last->flags |= NODE_NOSRC;
                }
        }
}

static void
post_ex(POST_ARGS)
{
        struct roff_node        *n;
        int                      ic;

        post_std(mdoc);

        n = mdoc->last;
        mdoc->next = ROFF_NEXT_CHILD;
        roff_word_alloc(mdoc, n->line, n->pos, "The");
        mdoc->last->flags |= NODE_NOSRC;

        if (mdoc->last->next != NULL)
                ic = build_list(mdoc, MDOC_Nm);
        else if (mdoc->meta.name != NULL) {
                roff_elem_alloc(mdoc, n->line, n->pos, MDOC_Nm);
                mdoc->last->flags |= NODE_NOSRC;
                roff_word_alloc(mdoc, n->line, n->pos, mdoc->meta.name);
                mdoc->last->flags |= NODE_NOSRC;
                mdoc->last = mdoc->last->parent;
                mdoc->next = ROFF_NEXT_SIBLING;
                ic = 1;
        } else {
                mandoc_msg(MANDOCERR_EX_NONAME, n->line, n->pos, "Ex");
                ic = 0;
        }

        roff_word_alloc(mdoc, n->line, n->pos,
            ic > 1 ? "utilities exit\\~0" : "utility exits\\~0");
        mdoc->last->flags |= NODE_NOSRC;
        roff_word_alloc(mdoc, n->line, n->pos,
            "on success, and\\~>0 if an error occurs.");
        mdoc->last->flags |= NODE_EOS | NODE_NOSRC;
        mdoc->last = n;
}

static void
post_lb(POST_ARGS)
{
        struct roff_node        *n;
        const char              *p;

        post_delim_nb(mdoc);

        n = mdoc->last;
        assert(n->child->type == ROFFT_TEXT);
        mdoc->next = ROFF_NEXT_CHILD;

        if ((p = mdoc_a2lib(n->child->string)) != NULL) {
                n->child->flags |= NODE_NOPRT;
                roff_word_alloc(mdoc, n->line, n->pos, p);
                mdoc->last->flags = NODE_NOSRC;
                mdoc->last = n;
                return;
        }

        mandoc_msg(MANDOCERR_LB_BAD, n->child->line,
            n->child->pos, "Lb %s", n->child->string);

        roff_word_alloc(mdoc, n->line, n->pos, "library");
        mdoc->last->flags = NODE_NOSRC;
        roff_word_alloc(mdoc, n->line, n->pos, "\\(lq");
        mdoc->last->flags = NODE_DELIMO | NODE_NOSRC;
        mdoc->last = mdoc->last->next;
        roff_word_alloc(mdoc, n->line, n->pos, "\\(rq");
        mdoc->last->flags = NODE_DELIMC | NODE_NOSRC;
        mdoc->last = n;
}

static void
post_rv(POST_ARGS)
{
        struct roff_node        *n;
        int                      ic;

        post_std(mdoc);

        n = mdoc->last;
        mdoc->next = ROFF_NEXT_CHILD;
        if (n->child != NULL) {
                roff_word_alloc(mdoc, n->line, n->pos, "The");
                mdoc->last->flags |= NODE_NOSRC;
                ic = build_list(mdoc, MDOC_Fn);
                roff_word_alloc(mdoc, n->line, n->pos,
                    ic > 1 ? "functions return" : "function returns");
                mdoc->last->flags |= NODE_NOSRC;
                roff_word_alloc(mdoc, n->line, n->pos,
                    "the value\\~0 if successful;");
        } else
                roff_word_alloc(mdoc, n->line, n->pos, "Upon successful "
                    "completion, the value\\~0 is returned;");
        mdoc->last->flags |= NODE_NOSRC;

        roff_word_alloc(mdoc, n->line, n->pos, "otherwise "
            "the value\\~\\-1 is returned and the global variable");
        mdoc->last->flags |= NODE_NOSRC;
        roff_elem_alloc(mdoc, n->line, n->pos, MDOC_Va);
        mdoc->last->flags |= NODE_NOSRC;
        roff_word_alloc(mdoc, n->line, n->pos, "errno");
        mdoc->last->flags |= NODE_NOSRC;
        mdoc->last = mdoc->last->parent;
        mdoc->next = ROFF_NEXT_SIBLING;
        roff_word_alloc(mdoc, n->line, n->pos,
            "is set to indicate the error.");
        mdoc->last->flags |= NODE_EOS | NODE_NOSRC;
        mdoc->last = n;
}

static void
post_std(POST_ARGS)
{
        struct roff_node *n;

        post_delim(mdoc);

        n = mdoc->last;
        if (n->args && n->args->argc == 1)
                if (n->args->argv[0].arg == MDOC_Std)
                        return;

        mandoc_msg(MANDOCERR_ARG_STD, n->line, n->pos,
            "%s", roff_name[n->tok]);
}

static void
post_st(POST_ARGS)
{
        struct roff_node         *n, *nch;
        const char               *p;

        n = mdoc->last;
        nch = n->child;
        assert(nch->type == ROFFT_TEXT);

        if ((p = mdoc_a2st(nch->string)) == NULL) {
                mandoc_msg(MANDOCERR_ST_BAD,
                    nch->line, nch->pos, "St %s", nch->string);
                roff_node_delete(mdoc, n);
                return;
        }

        nch->flags |= NODE_NOPRT;
        mdoc->next = ROFF_NEXT_CHILD;
        roff_word_alloc(mdoc, nch->line, nch->pos, p);
        mdoc->last->flags |= NODE_NOSRC;
        mdoc->last= n;
}

static void
post_tg(POST_ARGS)
{
        struct roff_node *n;    /* The .Tg node. */
        struct roff_node *nch;  /* The first child of the .Tg node. */
        struct roff_node *nn;   /* The next node after the .Tg node. */
        struct roff_node *np;   /* The parent of the next node. */
        struct roff_node *nt;   /* The TEXT node containing the tag. */
        size_t            len;  /* The number of bytes in the tag. */

        /* Find the next node. */
        n = mdoc->last;
        for (nn = n; nn != NULL; nn = nn->parent) {
                if (nn->next != NULL) {
                        nn = nn->next;
                        break;
                }
        }

        /* Find the tag. */
        nt = nch = n->child;
        if (nch == NULL && nn != NULL && nn->child != NULL &&
            nn->child->type == ROFFT_TEXT)
                nt = nn->child;

        /* Validate the tag. */
        if (nt == NULL || *nt->string == '\0')
                mandoc_msg(MANDOCERR_MACRO_EMPTY, n->line, n->pos, "Tg");
        if (nt == NULL) {
                roff_node_delete(mdoc, n);
                return;
        }
        len = strcspn(nt->string, " \t\\");
        if (nt->string[len] != '\0')
                mandoc_msg(MANDOCERR_TG_SPC, nt->line,
                    nt->pos + len, "Tg %s", nt->string);

        /* Keep only the first argument. */
        if (nch != NULL && nch->next != NULL) {
                mandoc_msg(MANDOCERR_ARG_EXCESS, nch->next->line,
                    nch->next->pos, "Tg ... %s", nch->next->string);
                while (nch->next != NULL)
                        roff_node_delete(mdoc, nch->next);
        }

        /* Drop the macro if the first argument is invalid. */
        if (len == 0 || nt->string[len] != '\0') {
                roff_node_delete(mdoc, n);
                return;
        }

        /* By default, tag the .Tg node itself. */
        if (nn == NULL || nn->flags & NODE_ID)
                nn = n;

        /* Explicit tagging of specific macros. */
        switch (nn->tok) {
        case MDOC_Sh:
        case MDOC_Ss:
        case MDOC_Fo:
                nn = nn->head->child == NULL ? n : nn->head;
                break;
        case MDOC_It:
                np = nn->parent;
                while (np->tok != MDOC_Bl)
                        np = np->parent;
                switch (np->norm->Bl.type) {
                case LIST_column:
                        break;
                case LIST_diag:
                case LIST_hang:
                case LIST_inset:
                case LIST_ohang:
                case LIST_tag:
                        nn = nn->head;
                        break;
                case LIST_bullet:
                case LIST_dash:
                case LIST_enum:
                case LIST_hyphen:
                case LIST_item:
                        nn = nn->body->child == NULL ? n : nn->body;
                        break;
                default:
                        abort();
                }
                break;
        case MDOC_Bd:
        case MDOC_Bl:
        case MDOC_D1:
        case MDOC_Dl:
                nn = nn->body->child == NULL ? n : nn->body;
                break;
        case MDOC_Pp:
                break;
        case MDOC_Cm:
        case MDOC_Dv:
        case MDOC_Em:
        case MDOC_Er:
        case MDOC_Ev:
        case MDOC_Fl:
        case MDOC_Fn:
        case MDOC_Ic:
        case MDOC_Li:
        case MDOC_Ms:
        case MDOC_No:
        case MDOC_Sy:
                if (nn->child == NULL)
                        nn = n;
                break;
        default:
                nn = n;
                break;
        }
        tag_put(nt->string, TAG_MANUAL, nn);
        if (nn != n)
                n->flags |= NODE_NOPRT;
}

static void
post_obsolete(POST_ARGS)
{
        struct roff_node *n;

        n = mdoc->last;
        if (n->type == ROFFT_ELEM || n->type == ROFFT_BLOCK)
                mandoc_msg(MANDOCERR_MACRO_OBS, n->line, n->pos,
                    "%s", roff_name[n->tok]);
}

static void
post_useless(POST_ARGS)
{
        struct roff_node *n;

        n = mdoc->last;
        mandoc_msg(MANDOCERR_MACRO_USELESS, n->line, n->pos,
            "%s", roff_name[n->tok]);
}

/*
 * Block macros.
 */

static void
post_bf(POST_ARGS)
{
        struct roff_node *np, *nch;

        /*
         * Unlike other data pointers, these are "housed" by the HEAD
         * element, which contains the goods.
         */

        np = mdoc->last;
        if (np->type != ROFFT_HEAD)
                return;

        assert(np->parent->type == ROFFT_BLOCK);
        assert(np->parent->tok == MDOC_Bf);

        /* Check the number of arguments. */

        nch = np->child;
        if (np->parent->args == NULL) {
                if (nch == NULL) {
                        mandoc_msg(MANDOCERR_BF_NOFONT,
                            np->line, np->pos, "Bf");
                        return;
                }
                nch = nch->next;
        }
        if (nch != NULL)
                mandoc_msg(MANDOCERR_ARG_EXCESS,
                    nch->line, nch->pos, "Bf ... %s", nch->string);

        /* Extract argument into data. */

        if (np->parent->args != NULL) {
                switch (np->parent->args->argv[0].arg) {
                case MDOC_Emphasis:
                        np->norm->Bf.font = FONT_Em;
                        break;
                case MDOC_Literal:
                        np->norm->Bf.font = FONT_Li;
                        break;
                case MDOC_Symbolic:
                        np->norm->Bf.font = FONT_Sy;
                        break;
                default:
                        abort();
                }
                return;
        }

        /* Extract parameter into data. */

        if ( ! strcmp(np->child->string, "Em"))
                np->norm->Bf.font = FONT_Em;
        else if ( ! strcmp(np->child->string, "Li"))
                np->norm->Bf.font = FONT_Li;
        else if ( ! strcmp(np->child->string, "Sy"))
                np->norm->Bf.font = FONT_Sy;
        else
                mandoc_msg(MANDOCERR_BF_BADFONT, np->child->line,
                    np->child->pos, "Bf %s", np->child->string);
}

static void
post_fname(POST_ARGS)
{
        struct roff_node        *n, *nch;
        const char              *cp;
        size_t                   pos;

        n = mdoc->last;
        nch = n->child;
        cp = nch->string;
        if (*cp == '(') {
                if (cp[strlen(cp + 1)] == ')')
                        return;
                pos = 0;
        } else {
                pos = strcspn(cp, "()");
                if (cp[pos] == '\0') {
                        if (n->sec == SEC_DESCRIPTION ||
                            n->sec == SEC_CUSTOM)
                                tag_put(NULL, fn_prio++, n);
                        return;
                }
        }
        mandoc_msg(MANDOCERR_FN_PAREN, nch->line, nch->pos + pos, "%s", cp);
}

static void
post_fn(POST_ARGS)
{
        post_fname(mdoc);
        post_fa(mdoc);
}

static void
post_fo(POST_ARGS)
{
        const struct roff_node  *n;

        n = mdoc->last;

        if (n->type != ROFFT_HEAD)
                return;

        if (n->child == NULL) {
                mandoc_msg(MANDOCERR_FO_NOHEAD, n->line, n->pos, "Fo");
                return;
        }
        if (n->child != n->last) {
                mandoc_msg(MANDOCERR_ARG_EXCESS,
                    n->child->next->line, n->child->next->pos,
                    "Fo ... %s", n->child->next->string);
                while (n->child != n->last)
                        roff_node_delete(mdoc, n->last);
        } else
                post_delim(mdoc);

        post_fname(mdoc);
}

static void
post_fa(POST_ARGS)
{
        const struct roff_node *n;
        const char *cp;

        for (n = mdoc->last->child; n != NULL; n = n->next) {
                for (cp = n->string; *cp != '\0'; cp++) {
                        /* Ignore callbacks and alterations. */
                        if (*cp == '(' || *cp == '{')
                                break;
                        if (*cp != ',')
                                continue;
                        mandoc_msg(MANDOCERR_FA_COMMA, n->line,
                            n->pos + (int)(cp - n->string), "%s", n->string);
                        break;
                }
        }
        post_delim_nb(mdoc);
}

static void
post_nm(POST_ARGS)
{
        struct roff_node        *n;

        n = mdoc->last;

        if (n->sec == SEC_NAME && n->child != NULL &&
            n->child->type == ROFFT_TEXT && mdoc->meta.msec != NULL)
                mandoc_xr_add(mdoc->meta.msec, n->child->string, -1, -1);

        if (n->last != NULL && n->last->tok == MDOC_Pp)
                roff_node_relink(mdoc, n->last);

        if (mdoc->meta.name == NULL)
                deroff(&mdoc->meta.name, n);

        if (mdoc->meta.name == NULL ||
            (mdoc->lastsec == SEC_NAME && n->child == NULL))
                mandoc_msg(MANDOCERR_NM_NONAME, n->line, n->pos, "Nm");

        switch (n->type) {
        case ROFFT_ELEM:
                post_delim_nb(mdoc);
                break;
        case ROFFT_HEAD:
                post_delim(mdoc);
                break;
        default:
                return;
        }

        if ((n->child != NULL && n->child->type == ROFFT_TEXT) ||
            mdoc->meta.name == NULL)
                return;

        mdoc->next = ROFF_NEXT_CHILD;
        roff_word_alloc(mdoc, n->line, n->pos, mdoc->meta.name);
        mdoc->last->flags |= NODE_NOSRC;
        mdoc->last = n;
}

static void
post_nd(POST_ARGS)
{
        struct roff_node        *n;

        n = mdoc->last;

        if (n->type != ROFFT_BODY)
                return;

        if (n->sec != SEC_NAME)
                mandoc_msg(MANDOCERR_ND_LATE, n->line, n->pos, "Nd");

        if (n->child == NULL)
                mandoc_msg(MANDOCERR_ND_EMPTY, n->line, n->pos, "Nd");
        else
                post_delim(mdoc);

        post_hyph(mdoc);
}

static void
post_display(POST_ARGS)
{
        struct roff_node *n, *np;

        n = mdoc->last;
        switch (n->type) {
        case ROFFT_BODY:
                if (n->end != ENDBODY_NOT) {
                        if (n->tok == MDOC_Bd &&
                            n->body->parent->args == NULL)
                                roff_node_delete(mdoc, n);
                } else if (n->child == NULL)
                        mandoc_msg(MANDOCERR_BLK_EMPTY, n->line, n->pos,
                            "%s", roff_name[n->tok]);
                else if (n->tok == MDOC_D1)
                        post_hyph(mdoc);
                break;
        case ROFFT_BLOCK:
                if (n->tok == MDOC_Bd) {
                        if (n->args == NULL) {
                                mandoc_msg(MANDOCERR_BD_NOARG,
                                    n->line, n->pos, "Bd");
                                mdoc->next = ROFF_NEXT_SIBLING;
                                while (n->body->child != NULL)
                                        roff_node_relink(mdoc,
                                            n->body->child);
                                roff_node_delete(mdoc, n);
                                break;
                        }
                        post_bd(mdoc);
                        post_prevpar(mdoc);
                }
                for (np = n->parent; np != NULL; np = np->parent) {
                        if (np->type == ROFFT_BLOCK && np->tok == MDOC_Bd) {
                                mandoc_msg(MANDOCERR_BD_NEST, n->line,
                                    n->pos, "%s in Bd", roff_name[n->tok]);
                                break;
                        }
                }
                break;
        default:
                break;
        }
}

static void
post_defaults(POST_ARGS)
{
        struct roff_node *n;

        n = mdoc->last;
        if (n->child != NULL) {
                post_delim_nb(mdoc);
                return;
        }
        mdoc->next = ROFF_NEXT_CHILD;
        switch (n->tok) {
        case MDOC_Ar:
                roff_word_alloc(mdoc, n->line, n->pos, "file");
                mdoc->last->flags |= NODE_NOSRC;
                roff_word_alloc(mdoc, n->line, n->pos, "...");
                break;
        case MDOC_Pa:
        case MDOC_Mt:
                roff_word_alloc(mdoc, n->line, n->pos, "~");
                break;
        default:
                abort();
        }
        mdoc->last->flags |= NODE_NOSRC;
        mdoc->last = n;
}

static void
post_at(POST_ARGS)
{
        struct roff_node        *n, *nch;
        const char              *att;

        n = mdoc->last;
        nch = n->child;

        /*
         * If we have a child, look it up in the standard keys.  If a
         * key exist, use that instead of the child; if it doesn't,
         * prefix "AT&T UNIX " to the existing data.
         */

        att = NULL;
        if (nch != NULL && ((att = mdoc_a2att(nch->string)) == NULL))
                mandoc_msg(MANDOCERR_AT_BAD,
                    nch->line, nch->pos, "At %s", nch->string);

        mdoc->next = ROFF_NEXT_CHILD;
        if (att != NULL) {
                roff_word_alloc(mdoc, nch->line, nch->pos, att);
                nch->flags |= NODE_NOPRT;
        } else
                roff_word_alloc(mdoc, n->line, n->pos, "AT&T UNIX");
        mdoc->last->flags |= NODE_NOSRC;
        mdoc->last = n;
}

static void
post_an(POST_ARGS)
{
        struct roff_node *np, *nch;

        post_an_norm(mdoc);

        np = mdoc->last;
        nch = np->child;
        if (np->norm->An.auth == AUTH__NONE) {
                if (nch == NULL)
                        mandoc_msg(MANDOCERR_MACRO_EMPTY,
                            np->line, np->pos, "An");
                else
                        post_delim_nb(mdoc);
        } else if (nch != NULL)
                mandoc_msg(MANDOCERR_ARG_EXCESS,
                    nch->line, nch->pos, "An ... %s", nch->string);
}

static void
post_em(POST_ARGS)
{
        post_tag(mdoc);
        tag_put(NULL, TAG_FALLBACK, mdoc->last);
}

static void
post_en(POST_ARGS)
{
        post_obsolete(mdoc);
        if (mdoc->last->type == ROFFT_BLOCK)
                mdoc->last->norm->Es = mdoc->last_es;
}

static void
post_er(POST_ARGS)
{
        struct roff_node *n;

        n = mdoc->last;
        if (n->sec == SEC_ERRORS &&
            (n->parent->tok == MDOC_It ||
             (n->parent->tok == MDOC_Bq &&
              n->parent->parent->parent->tok == MDOC_It)))
                tag_put(NULL, TAG_STRONG, n);
        post_delim_nb(mdoc);
}

static void
post_tag(POST_ARGS)
{
        struct roff_node *n;

        n = mdoc->last;
        if ((n->prev == NULL ||
             (n->prev->type == ROFFT_TEXT &&
              strcmp(n->prev->string, "|") == 0)) &&
            (n->parent->tok == MDOC_It ||
             (n->parent->tok == MDOC_Xo &&
              n->parent->parent->prev == NULL &&
              n->parent->parent->parent->tok == MDOC_It)))
                tag_put(NULL, TAG_STRONG, n);
        post_delim_nb(mdoc);
}

static void
post_es(POST_ARGS)
{
        post_obsolete(mdoc);
        mdoc->last_es = mdoc->last;
}

static void
post_fl(POST_ARGS)
{
        struct roff_node        *n;
        char                    *cp;

        /*
         * Transform ".Fl Fl long" to ".Fl \-long",
         * resulting for example in better HTML output.
         */

        n = mdoc->last;
        if (n->prev != NULL && n->prev->tok == MDOC_Fl &&
            n->prev->child == NULL && n->child != NULL &&
            (n->flags & NODE_LINE) == 0) {
                mandoc_asprintf(&cp, "\\-%s", n->child->string);
                free(n->child->string);
                n->child->string = cp;
                roff_node_delete(mdoc, n->prev);
        }
        post_tag(mdoc);
}

static void
post_xx(POST_ARGS)
{
        struct roff_node        *n;
        const char              *os;
        char                    *v;

        post_delim_nb(mdoc);

        n = mdoc->last;
        switch (n->tok) {
        case MDOC_Bsx:
                os = "BSD/OS";
                break;
        case MDOC_Dx:
                os = "DragonFly";
                break;
        case MDOC_Fx:
                os = "FreeBSD";
                break;
        case MDOC_Nx:
                os = "NetBSD";
                if (n->child == NULL)
                        break;
                v = n->child->string;
                if ((v[0] != '0' && v[0] != '1') || v[1] != '.' ||
                    v[2] < '0' || v[2] > '9' ||
                    v[3] < 'a' || v[3] > 'z' || v[4] != '\0')
                        break;
                n->child->flags |= NODE_NOPRT;
                mdoc->next = ROFF_NEXT_CHILD;
                roff_word_alloc(mdoc, n->child->line, n->child->pos, v);
                v = mdoc->last->string;
                v[3] = toupper((unsigned char)v[3]);
                mdoc->last->flags |= NODE_NOSRC;
                mdoc->last = n;
                break;
        case MDOC_Ox:
                os = "OpenBSD";
                break;
        case MDOC_Ux:
                os = "UNIX";
                break;
        default:
                abort();
        }
        mdoc->next = ROFF_NEXT_CHILD;
        roff_word_alloc(mdoc, n->line, n->pos, os);
        mdoc->last->flags |= NODE_NOSRC;
        mdoc->last = n;
}

static void
post_it(POST_ARGS)
{
        struct roff_node *nbl, *nit, *nch;
        int               i, cols;
        enum mdoc_list    lt;

        post_prevpar(mdoc);

        nit = mdoc->last;
        if (nit->type != ROFFT_BLOCK)
                return;

        nbl = nit->parent->parent;
        lt = nbl->norm->Bl.type;

        switch (lt) {
        case LIST_tag:
        case LIST_hang:
        case LIST_ohang:
        case LIST_inset:
        case LIST_diag:
                if (nit->head->child == NULL)
                        mandoc_msg(MANDOCERR_IT_NOHEAD,
                            nit->line, nit->pos, "Bl -%s It",
                            mdoc_argnames[nbl->args->argv[0].arg]);
                break;
        case LIST_bullet:
        case LIST_dash:
        case LIST_enum:
        case LIST_hyphen:
                if (nit->body == NULL || nit->body->child == NULL)
                        mandoc_msg(MANDOCERR_IT_NOBODY,
                            nit->line, nit->pos, "Bl -%s It",
                            mdoc_argnames[nbl->args->argv[0].arg]);
                /* FALLTHROUGH */
        case LIST_item:
                if ((nch = nit->head->child) != NULL)
                        mandoc_msg(MANDOCERR_ARG_SKIP,
                            nit->line, nit->pos, "It %s",
                            nch->type == ROFFT_TEXT ? nch->string :
                            roff_name[nch->tok]);
                break;
        case LIST_column:
                cols = (int)nbl->norm->Bl.ncols;

                assert(nit->head->child == NULL);

                if (nit->head->next->child == NULL &&
                    nit->head->next->next == NULL) {
                        mandoc_msg(MANDOCERR_MACRO_EMPTY,
                            nit->line, nit->pos, "It");
                        roff_node_delete(mdoc, nit);
                        break;
                }

                i = 0;
                for (nch = nit->child; nch != NULL; nch = nch->next) {
                        if (nch->type != ROFFT_BODY)
                                continue;
                        if (i++ && nch->flags & NODE_LINE)
                                mandoc_msg(MANDOCERR_TA_LINE,
                                    nch->line, nch->pos, "Ta");
                }
                if (i < cols || i > cols + 1)
                        mandoc_msg(MANDOCERR_BL_COL, nit->line, nit->pos,
                            "%d columns, %d cells", cols, i);
                else if (nit->head->next->child != NULL &&
                    nit->head->next->child->flags & NODE_LINE)
                        mandoc_msg(MANDOCERR_IT_NOARG,
                            nit->line, nit->pos, "Bl -column It");
                break;
        default:
                abort();
        }
}

static void
post_bl_block(POST_ARGS)
{
        struct roff_node *n, *ni, *nc;

        post_prevpar(mdoc);

        n = mdoc->last;
        for (ni = n->body->child; ni != NULL; ni = ni->next) {
                if (ni->body == NULL)
                        continue;
                nc = ni->body->last;
                while (nc != NULL) {
                        switch (nc->tok) {
                        case MDOC_Pp:
                        case ROFF_br:
                                break;
                        default:
                                nc = NULL;
                                continue;
                        }
                        if (ni->next == NULL) {
                                mandoc_msg(MANDOCERR_PAR_MOVE, nc->line,
                                    nc->pos, "%s", roff_name[nc->tok]);
                                roff_node_relink(mdoc, nc);
                        } else if (n->norm->Bl.comp == 0 &&
                            n->norm->Bl.type != LIST_column) {
                                mandoc_msg(MANDOCERR_PAR_SKIP,
                                    nc->line, nc->pos,
                                    "%s before It", roff_name[nc->tok]);
                                roff_node_delete(mdoc, nc);
                        } else
                                break;
                        nc = ni->body->last;
                }
        }
}

/*
 * If the argument of -offset or -width is a macro,
 * replace it with the associated default width.
 */
static void
rewrite_macro2len(struct roff_man *mdoc, char **arg)
{
        size_t            width;
        enum roff_tok     tok;

        if (*arg == NULL)
                return;
        else if ( ! strcmp(*arg, "Ds"))
                width = 6;
        else if ((tok = roffhash_find(mdoc->mdocmac, *arg, 0)) == TOKEN_NONE)
                return;
        else
                width = macro2len(tok);

        free(*arg);
        mandoc_asprintf(arg, "%zun", width);
}

static void
post_bl_head(POST_ARGS)
{
        struct roff_node *nbl, *nh, *nch, *nnext;
        struct mdoc_argv *argv;
        int               i, j;

        post_bl_norm(mdoc);

        nh = mdoc->last;
        if (nh->norm->Bl.type != LIST_column) {
                if ((nch = nh->child) == NULL)
                        return;
                mandoc_msg(MANDOCERR_ARG_EXCESS,
                    nch->line, nch->pos, "Bl ... %s", nch->string);
                while (nch != NULL) {
                        roff_node_delete(mdoc, nch);
                        nch = nh->child;
                }
                return;
        }

        /*
         * Append old-style lists, where the column width specifiers
         * trail as macro parameters, to the new-style ("normal-form")
         * lists where they're argument values following -column.
         */

        if (nh->child == NULL)
                return;

        nbl = nh->parent;
        for (j = 0; j < (int)nbl->args->argc; j++)
                if (nbl->args->argv[j].arg == MDOC_Column)
                        break;

        assert(j < (int)nbl->args->argc);

        /*
         * Accommodate 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.
         */

        argv = nbl->args->argv + j;
        i = argv->sz;
        for (nch = nh->child; nch != NULL; nch = nch->next)
                argv->sz++;
        argv->value = mandoc_reallocarray(argv->value,
            argv->sz, sizeof(char *));

        nh->norm->Bl.ncols = argv->sz;
        nh->norm->Bl.cols = (void *)argv->value;

        for (nch = nh->child; nch != NULL; nch = nnext) {
                argv->value[i++] = nch->string;
                nch->string = NULL;
                nnext = nch->next;
                roff_node_delete(NULL, nch);
        }
        nh->child = NULL;
}

static void
post_bl(POST_ARGS)
{
        struct roff_node        *nbody;           /* of the Bl */
        struct roff_node        *nchild, *nnext;  /* of the Bl body */
        const char              *prev_Er;
        int                      order;

        nbody = mdoc->last;
        switch (nbody->type) {
        case ROFFT_BLOCK:
                post_bl_block(mdoc);
                return;
        case ROFFT_HEAD:
                post_bl_head(mdoc);
                return;
        case ROFFT_BODY:
                break;
        default:
                return;
        }
        if (nbody->end != ENDBODY_NOT)
                return;

        /*
         * Up to the first item, move nodes before the list,
         * but leave transparent nodes where they are
         * if they precede an item.
         * The next non-transparent node is kept in nchild.
         * It only needs to be updated after a non-transparent
         * node was moved out, and at the very beginning
         * when no node at all was moved yet.
         */

        nchild = mdoc->last;
        for (;;) {
                if (nchild == mdoc->last)
                        nchild = roff_node_child(nbody);
                if (nchild == NULL) {
                        mdoc->last = nbody;
                        mandoc_msg(MANDOCERR_BLK_EMPTY,
                            nbody->line, nbody->pos, "Bl");
                        return;
                }
                if (nchild->tok == MDOC_It) {
                        mdoc->last = nbody;
                        break;
                }
                mandoc_msg(MANDOCERR_BL_MOVE, nbody->child->line,
                    nbody->child->pos, "%s", roff_name[nbody->child->tok]);
                if (nbody->parent->prev == NULL) {
                        mdoc->last = nbody->parent->parent;
                        mdoc->next = ROFF_NEXT_CHILD;
                } else {
                        mdoc->last = nbody->parent->prev;
                        mdoc->next = ROFF_NEXT_SIBLING;
                }
                roff_node_relink(mdoc, nbody->child);
        }

        /*
         * We have reached the first item,
         * so moving nodes out is no longer possible.
         * But in .Bl -column, the first rows may be implicit,
         * that is, they may not start with .It macros.
         * Such rows may be followed by nodes generated on the
         * roff level, for example .TS.
         * Wrap such roff nodes into an implicit row.
         */

        while (nchild != NULL) {
                if (nchild->tok == MDOC_It) {
                        nchild = roff_node_next(nchild);
                        continue;
                }
                nnext = nchild->next;
                mdoc->last = nchild->prev;
                mdoc->next = ROFF_NEXT_SIBLING;
                roff_block_alloc(mdoc, nchild->line, nchild->pos, MDOC_It);
                roff_head_alloc(mdoc, nchild->line, nchild->pos, MDOC_It);
                mdoc->next = ROFF_NEXT_SIBLING;
                roff_body_alloc(mdoc, nchild->line, nchild->pos, MDOC_It);
                while (nchild->tok != MDOC_It) {
                        roff_node_relink(mdoc, nchild);
                        if (nnext == NULL)
                                break;
                        nchild = nnext;
                        nnext = nchild->next;
                        mdoc->next = ROFF_NEXT_SIBLING;
                }
                mdoc->last = nbody;
        }

        if (mdoc->meta.os_e != MANDOC_OS_NETBSD)
                return;

        prev_Er = NULL;
        for (nchild = nbody->child; nchild != NULL; nchild = nchild->next) {
                if (nchild->tok != MDOC_It)
                        continue;
                if ((nnext = nchild->head->child) == NULL)
                        continue;
                if (nnext->type == ROFFT_BLOCK)
                        nnext = nnext->body->child;
                if (nnext == NULL || nnext->tok != MDOC_Er)
                        continue;
                nnext = nnext->child;
                if (prev_Er != NULL) {
                        order = strcmp(prev_Er, nnext->string);
                        if (order > 0)
                                mandoc_msg(MANDOCERR_ER_ORDER,
                                    nnext->line, nnext->pos,
                                    "Er %s %s (NetBSD)",
                                    prev_Er, nnext->string);
                        else if (order == 0)
                                mandoc_msg(MANDOCERR_ER_REP,
                                    nnext->line, nnext->pos,
                                    "Er %s (NetBSD)", prev_Er);
                }
                prev_Er = nnext->string;
        }
}

static void
post_bk(POST_ARGS)
{
        struct roff_node        *n;

        n = mdoc->last;

        if (n->type == ROFFT_BLOCK && n->body->child == NULL) {
                mandoc_msg(MANDOCERR_BLK_EMPTY, n->line, n->pos, "Bk");
                roff_node_delete(mdoc, n);
        }
}

static void
post_sm(POST_ARGS)
{
        struct roff_node        *nch;

        nch = mdoc->last->child;

        if (nch == NULL) {
                mdoc->flags ^= MDOC_SMOFF;
                return;
        }

        assert(nch->type == ROFFT_TEXT);

        if ( ! strcmp(nch->string, "on")) {
                mdoc->flags &= ~MDOC_SMOFF;
                return;
        }
        if ( ! strcmp(nch->string, "off")) {
                mdoc->flags |= MDOC_SMOFF;
                return;
        }

        mandoc_msg(MANDOCERR_SM_BAD, nch->line, nch->pos,
            "%s %s", roff_name[mdoc->last->tok], nch->string);
        roff_node_relink(mdoc, nch);
        return;
}

static void
post_root(POST_ARGS)
{
        struct roff_node *n;

        /* Add missing prologue data. */

        if (mdoc->meta.date == NULL)
                mdoc->meta.date = mandoc_normdate(NULL, NULL);

        if (mdoc->meta.title == NULL) {
                mandoc_msg(MANDOCERR_DT_NOTITLE, 0, 0, "EOF");
                mdoc->meta.title = mandoc_strdup("UNTITLED");
        }

        if (mdoc->meta.vol == NULL)
                mdoc->meta.vol = mandoc_strdup("LOCAL");

        if (mdoc->meta.os == NULL) {
                mandoc_msg(MANDOCERR_OS_MISSING, 0, 0, NULL);
                mdoc->meta.os = mandoc_strdup("");
        } else if (mdoc->meta.os_e &&
            (mdoc->meta.rcsids & (1 << mdoc->meta.os_e)) == 0)
                mandoc_msg(MANDOCERR_RCS_MISSING, 0, 0,
                    mdoc->meta.os_e == MANDOC_OS_OPENBSD ?
                    "(OpenBSD)" : "(NetBSD)");

        if (mdoc->meta.arch != NULL &&
            arch_valid(mdoc->meta.arch, mdoc->meta.os_e) == 0) {
                n = mdoc->meta.first->child;
                while (n->tok != MDOC_Dt ||
                    n->child == NULL ||
                    n->child->next == NULL ||
                    n->child->next->next == NULL)
                        n = n->next;
                n = n->child->next->next;
                mandoc_msg(MANDOCERR_ARCH_BAD, n->line, n->pos,
                    "Dt ... %s %s", mdoc->meta.arch,
                    mdoc->meta.os_e == MANDOC_OS_OPENBSD ?
                    "(OpenBSD)" : "(NetBSD)");
        }

        /* Check that we begin with a proper `Sh'. */

        n = mdoc->meta.first->child;
        while (n != NULL &&
            (n->type == ROFFT_COMMENT ||
             (n->tok >= MDOC_Dd &&
              mdoc_macro(n->tok)->flags & MDOC_PROLOGUE)))
                n = n->next;

        if (n == NULL)
                mandoc_msg(MANDOCERR_DOC_EMPTY, 0, 0, NULL);
        else if (n->tok != MDOC_Sh)
                mandoc_msg(MANDOCERR_SEC_BEFORE, n->line, n->pos,
                    "%s", roff_name[n->tok]);
}

static void
post_rs(POST_ARGS)
{
        struct roff_node *np, *nch, *next, *prev;
        int               i, j;

        np = mdoc->last;

        if (np->type != ROFFT_BODY)
                return;

        if (np->child == NULL) {
                mandoc_msg(MANDOCERR_RS_EMPTY, np->line, np->pos, "Rs");
                return;
        }

        /*
         * The full `Rs' block needs special handling to order the
         * sub-elements according to `rsord'.  Pick through each element
         * and correctly order it.  This is an insertion sort.
         */

        next = NULL;
        for (nch = np->child->next; nch != NULL; nch = next) {
                /* Determine order number of this child. */
                for (i = 0; i < RSORD_MAX; i++)
                        if (rsord[i] == nch->tok)
                                break;

                if (i == RSORD_MAX) {
                        mandoc_msg(MANDOCERR_RS_BAD, nch->line, nch->pos,
                            "%s", roff_name[nch->tok]);
                        i = -1;
                } else if (nch->tok == MDOC__J || nch->tok == MDOC__B)
                        np->norm->Rs.quote_T++;

                /*
                 * Remove this child from the chain.  This somewhat
                 * repeats roff_node_unlink(), but since we're
                 * just re-ordering, there's no need for the
                 * full unlink process.
                 */

                if ((next = nch->next) != NULL)
                        next->prev = nch->prev;

                if ((prev = nch->prev) != NULL)
                        prev->next = nch->next;

                nch->prev = nch->next = NULL;

                /*
                 * Scan back until we reach a node that's
                 * to be ordered before this child.
                 */

                for ( ; prev ; prev = prev->prev) {
                        /* Determine order of `prev'. */
                        for (j = 0; j < RSORD_MAX; j++)
                                if (rsord[j] == prev->tok)
                                        break;
                        if (j == RSORD_MAX)
                                j = -1;

                        if (j <= i)
                                break;
                }

                /*
                 * Set this child back into its correct place
                 * in front of the `prev' node.
                 */

                nch->prev = prev;

                if (prev == NULL) {
                        np->child->prev = nch;
                        nch->next = np->child;
                        np->child = nch;
                } else {
                        if (prev->next)
                                prev->next->prev = nch;
                        nch->next = prev->next;
                        prev->next = nch;
                }
        }
}

/*
 * For some arguments of some macros,
 * convert all breakable hyphens into ASCII_HYPH.
 */
static void
post_hyph(POST_ARGS)
{
        struct roff_node        *n, *nch;
        char                    *cp;

        n = mdoc->last;
        for (nch = n->child; nch != NULL; nch = nch->next) {
                if (nch->type != ROFFT_TEXT)
                        continue;
                cp = nch->string;
                if (*cp == '\0')
                        continue;
                while (*(++cp) != '\0')
                        if (*cp == '-' &&
                            isalpha((unsigned char)cp[-1]) &&
                            isalpha((unsigned char)cp[1])) {
                                if (n->tag == NULL && n->flags & NODE_ID)
                                        n->tag = mandoc_strdup(nch->string);
                                *cp = ASCII_HYPH;
                        }
        }
}

static void
post_ns(POST_ARGS)
{
        struct roff_node        *n;

        n = mdoc->last;
        if (n->flags & NODE_LINE ||
            (n->next != NULL && n->next->flags & NODE_DELIMC))
                mandoc_msg(MANDOCERR_NS_SKIP, n->line, n->pos, NULL);
}

static void
post_sx(POST_ARGS)
{
        post_delim(mdoc);
        post_hyph(mdoc);
}

static void
post_sh(POST_ARGS)
{
        post_section(mdoc);

        switch (mdoc->last->type) {
        case ROFFT_HEAD:
                post_sh_head(mdoc);
                break;
        case ROFFT_BODY:
                switch (mdoc->lastsec)  {
                case SEC_NAME:
                        post_sh_name(mdoc);
                        break;
                case SEC_SEE_ALSO:
                        post_sh_see_also(mdoc);
                        break;
                case SEC_AUTHORS:
                        post_sh_authors(mdoc);
                        break;
                default:
                        break;
                }
                break;
        default:
                break;
        }
}

static void
post_sh_name(POST_ARGS)
{
        struct roff_node *n;
        int hasnm, hasnd;

        hasnm = hasnd = 0;

        for (n = mdoc->last->child; n != NULL; n = n->next) {
                switch (n->tok) {
                case MDOC_Nm:
                        if (hasnm && n->child != NULL)
                                mandoc_msg(MANDOCERR_NAMESEC_PUNCT,
                                    n->line, n->pos,
                                    "Nm %s", n->child->string);
                        hasnm = 1;
                        continue;
                case MDOC_Nd:
                        hasnd = 1;
                        if (n->next != NULL)
                                mandoc_msg(MANDOCERR_NAMESEC_ND,
                                    n->line, n->pos, NULL);
                        break;
                case TOKEN_NONE:
                        if (n->type == ROFFT_TEXT &&
                            n->string[0] == ',' && n->string[1] == '\0' &&
                            n->next != NULL && n->next->tok == MDOC_Nm) {
                                n = n->next;
                                continue;
                        }
                        /* FALLTHROUGH */
                default:
                        mandoc_msg(MANDOCERR_NAMESEC_BAD,
                            n->line, n->pos, "%s", roff_name[n->tok]);
                        continue;
                }
                break;
        }

        if ( ! hasnm)
                mandoc_msg(MANDOCERR_NAMESEC_NONM,
                    mdoc->last->line, mdoc->last->pos, NULL);
        if ( ! hasnd)
                mandoc_msg(MANDOCERR_NAMESEC_NOND,
                    mdoc->last->line, mdoc->last->pos, NULL);
}

static void
post_sh_see_also(POST_ARGS)
{
        const struct roff_node  *n;
        const char              *name, *sec;
        const char              *lastname, *lastsec, *lastpunct;
        int                      cmp;

        n = mdoc->last->child;
        lastname = lastsec = lastpunct = NULL;
        while (n != NULL) {
                if (n->tok != MDOC_Xr ||
                    n->child == NULL ||
                    n->child->next == NULL)
                        break;

                /* Process one .Xr node. */

                name = n->child->string;
                sec = n->child->next->string;
                if (lastsec != NULL) {
                        if (lastpunct[0] != ',' || lastpunct[1] != '\0')
                                mandoc_msg(MANDOCERR_XR_PUNCT, n->line,
                                    n->pos, "%s before %s(%s)",
                                    lastpunct, name, sec);
                        cmp = strcmp(lastsec, sec);
                        if (cmp > 0)
                                mandoc_msg(MANDOCERR_XR_ORDER, n->line,
                                    n->pos, "%s(%s) after %s(%s)",
                                    name, sec, lastname, lastsec);
                        else if (cmp == 0 &&
                            strcasecmp(lastname, name) > 0)
                                mandoc_msg(MANDOCERR_XR_ORDER, n->line,
                                    n->pos, "%s after %s", name, lastname);
                }
                lastname = name;
                lastsec = sec;

                /* Process the following node. */

                n = n->next;
                if (n == NULL)
                        break;
                if (n->tok == MDOC_Xr) {
                        lastpunct = "none";
                        continue;
                }
                if (n->type != ROFFT_TEXT)
                        break;
                for (name = n->string; *name != '\0'; name++)
                        if (isalpha((const unsigned char)*name))
                                return;
                lastpunct = n->string;
                if (n->next == NULL || n->next->tok == MDOC_Rs)
                        mandoc_msg(MANDOCERR_XR_PUNCT, n->line,
                            n->pos, "%s after %s(%s)",
                            lastpunct, lastname, lastsec);
                n = n->next;
        }
}

static int
child_an(const struct roff_node *n)
{

        for (n = n->child; n != NULL; n = n->next)
                if ((n->tok == MDOC_An && n->child != NULL) || child_an(n))
                        return 1;
        return 0;
}

static void
post_sh_authors(POST_ARGS)
{

        if ( ! child_an(mdoc->last))
                mandoc_msg(MANDOCERR_AN_MISSING,
                    mdoc->last->line, mdoc->last->pos, NULL);
}

/*
 * Return an upper bound for the string distance (allowing
 * transpositions).  Not a full Levenshtein implementation
 * because Levenshtein is quadratic in the string length
 * and this function is called for every standard name,
 * so the check for each custom name would be cubic.
 * The following crude heuristics is linear, resulting
 * in quadratic behaviour for checking one custom name,
 * which does not cause measurable slowdown.
 */
static int
similar(const char *s1, const char *s2)
{
        const int       maxdist = 3;
        int             dist = 0;

        while (s1[0] != '\0' && s2[0] != '\0') {
                if (s1[0] == s2[0]) {
                        s1++;
                        s2++;
                        continue;
                }
                if (++dist > maxdist)
                        return INT_MAX;
                if (s1[1] == s2[1]) {  /* replacement */
                        s1++;
                        s2++;
                } else if (s1[0] == s2[1] && s1[1] == s2[0]) {
                        s1 += 2;        /* transposition */
                        s2 += 2;
                } else if (s1[0] == s2[1])  /* insertion */
                        s2++;
                else if (s1[1] == s2[0])  /* deletion */
                        s1++;
                else
                        return INT_MAX;
        }
        dist += strlen(s1) + strlen(s2);
        return dist > maxdist ? INT_MAX : dist;
}

static void
post_sh_head(POST_ARGS)
{
        struct roff_node        *nch;
        const char              *goodsec;
        const char *const       *testsec;
        int                      dist, mindist;
        enum roff_sec            sec;

        /*
         * Process a new section.  Sections are either "named" or
         * "custom".  Custom sections are user-defined, while named ones
         * follow a conventional order and may only appear in certain
         * manual sections.
         */

        sec = mdoc->last->sec;

        /* The NAME should be first. */

        if (sec != SEC_NAME && mdoc->lastnamed == SEC_NONE)
                mandoc_msg(MANDOCERR_NAMESEC_FIRST,
                    mdoc->last->line, mdoc->last->pos, "Sh %s",
                    sec != SEC_CUSTOM ? secnames[sec] :
                    (nch = mdoc->last->child) == NULL ? "" :
                    nch->type == ROFFT_TEXT ? nch->string :
                    roff_name[nch->tok]);

        /* The SYNOPSIS gets special attention in other areas. */

        if (sec == SEC_SYNOPSIS) {
                roff_setreg(mdoc->roff, "nS", 1, '=');
                mdoc->flags |= MDOC_SYNOPSIS;
        } else {
                roff_setreg(mdoc->roff, "nS", 0, '=');
                mdoc->flags &= ~MDOC_SYNOPSIS;
        }
        if (sec == SEC_DESCRIPTION)
                fn_prio = TAG_STRONG;

        /* Mark our last section. */

        mdoc->lastsec = sec;

        /* We don't care about custom sections after this. */

        if (sec == SEC_CUSTOM) {
                if ((nch = mdoc->last->child) == NULL ||
                    nch->type != ROFFT_TEXT || nch->next != NULL)
                        return;
                goodsec = NULL;
                mindist = INT_MAX;
                for (testsec = secnames + 1; *testsec != NULL; testsec++) {
                        dist = similar(nch->string, *testsec);
                        if (dist < mindist) {
                                goodsec = *testsec;
                                mindist = dist;
                        }
                }
                if (goodsec != NULL)
                        mandoc_msg(MANDOCERR_SEC_TYPO, nch->line, nch->pos,
                            "Sh %s instead of %s", nch->string, goodsec);
                return;
        }

        /*
         * Check whether our non-custom section is being repeated or is
         * out of order.
         */

        if (sec == mdoc->lastnamed)
                mandoc_msg(MANDOCERR_SEC_REP, mdoc->last->line,
                    mdoc->last->pos, "Sh %s", secnames[sec]);

        if (sec < mdoc->lastnamed)
                mandoc_msg(MANDOCERR_SEC_ORDER, mdoc->last->line,
                    mdoc->last->pos, "Sh %s", secnames[sec]);

        /* Mark the last named section. */

        mdoc->lastnamed = sec;

        /* Check particular section/manual conventions. */

        if (mdoc->meta.msec == NULL)
                return;

        goodsec = NULL;
        switch (sec) {
        case SEC_ERRORS:
        case SEC_RETURN_VALUES:
                if (*mdoc->meta.msec == '4')
                        break;
                if (*mdoc->meta.msec == '7')
                        break;
                goodsec = "2, 3, 4, 7, 9";
                /* FALLTHROUGH */
        case SEC_LIBRARY:
                if (*mdoc->meta.msec == '2')
                        break;
                if (*mdoc->meta.msec == '3')
                        break;
                if (NULL == goodsec)
                        goodsec = "2, 3, 9";
                /* FALLTHROUGH */
        case SEC_CONTEXT:
                if (*mdoc->meta.msec == '9')
                        break;
                if (NULL == goodsec)
                        goodsec = "9";
                mandoc_msg(MANDOCERR_SEC_MSEC,
                    mdoc->last->line, mdoc->last->pos,
                    "Sh %s for %s only", secnames[sec], goodsec);
                break;
        default:
                break;
        }
}

static void
post_xr(POST_ARGS)
{
        struct roff_node *n, *nch;

        n = mdoc->last;
        nch = n->child;
        if (nch->next == NULL) {
                mandoc_msg(MANDOCERR_XR_NOSEC,
                    n->line, n->pos, "Xr %s", nch->string);
        } else {
                assert(nch->next == n->last);
                if(mandoc_xr_add(nch->next->string, nch->string,
                    nch->line, nch->pos))
                        mandoc_msg(MANDOCERR_XR_SELF,
                            nch->line, nch->pos, "Xr %s %s",
                            nch->string, nch->next->string);
        }
        post_delim_nb(mdoc);
}

static void
post_section(POST_ARGS)
{
        struct roff_node *n, *nch;
        char             *cp, *tag;

        n = mdoc->last;
        switch (n->type) {
        case ROFFT_BLOCK:
                post_prevpar(mdoc);
                return;
        case ROFFT_HEAD:
                tag = NULL;
                deroff(&tag, n);
                if (tag != NULL) {
                        for (cp = tag; *cp != '\0'; cp++)
                                if (*cp == ' ')
                                        *cp = '_';
                        if ((nch = n->child) != NULL &&
                            nch->type == ROFFT_TEXT &&
                            strcmp(nch->string, tag) == 0)
                                tag_put(NULL, TAG_STRONG, n);
                        else
                                tag_put(tag, TAG_FALLBACK, n);
                        free(tag);
                }
                post_delim(mdoc);
                post_hyph(mdoc);
                return;
        case ROFFT_BODY:
                break;
        default:
                return;
        }
        if ((nch = n->child) != NULL &&
            (nch->tok == MDOC_Pp || nch->tok == ROFF_br ||
             nch->tok == ROFF_sp)) {
                mandoc_msg(MANDOCERR_PAR_SKIP, nch->line, nch->pos,
                    "%s after %s", roff_name[nch->tok],
                    roff_name[n->tok]);
                roff_node_delete(mdoc, nch);
        }
        if ((nch = n->last) != NULL &&
            (nch->tok == MDOC_Pp || nch->tok == ROFF_br)) {
                mandoc_msg(MANDOCERR_PAR_SKIP, nch->line, nch->pos,
                    "%s at the end of %s", roff_name[nch->tok],
                    roff_name[n->tok]);
                roff_node_delete(mdoc, nch);
        }
}

static void
post_prevpar(POST_ARGS)
{
        struct roff_node *n, *np;

        n = mdoc->last;
        if (n->type != ROFFT_ELEM && n->type != ROFFT_BLOCK)
                return;
        if ((np = roff_node_prev(n)) == NULL)
                return;

        /*
         * Don't allow `Pp' prior to a paragraph-type
         * block: `Pp' or non-compact `Bd' or `Bl'.
         */

        if (np->tok != MDOC_Pp && np->tok != ROFF_br)
                return;
        if (n->tok == MDOC_Bl && n->norm->Bl.comp)
                return;
        if (n->tok == MDOC_Bd && n->norm->Bd.comp)
                return;
        if (n->tok == MDOC_It && n->parent->norm->Bl.comp)
                return;

        mandoc_msg(MANDOCERR_PAR_SKIP, np->line, np->pos,
            "%s before %s", roff_name[np->tok], roff_name[n->tok]);
        roff_node_delete(mdoc, np);
}

static void
post_par(POST_ARGS)
{
        struct roff_node *np;

        fn_prio = TAG_STRONG;
        post_prevpar(mdoc);

        np = mdoc->last;
        if (np->child != NULL)
                mandoc_msg(MANDOCERR_ARG_SKIP, np->line, np->pos,
                    "%s %s", roff_name[np->tok], np->child->string);
}

static void
post_dd(POST_ARGS)
{
        struct roff_node *n;

        n = mdoc->last;
        n->flags |= NODE_NOPRT;

        if (mdoc->meta.date != NULL) {
                mandoc_msg(MANDOCERR_PROLOG_REP, n->line, n->pos, "Dd");
                free(mdoc->meta.date);
        } else if (mdoc->flags & MDOC_PBODY)
                mandoc_msg(MANDOCERR_PROLOG_LATE, n->line, n->pos, "Dd");
        else if (mdoc->meta.title != NULL)
                mandoc_msg(MANDOCERR_PROLOG_ORDER,
                    n->line, n->pos, "Dd after Dt");
        else if (mdoc->meta.os != NULL)
                mandoc_msg(MANDOCERR_PROLOG_ORDER,
                    n->line, n->pos, "Dd after Os");

        if (mdoc->quick && n != NULL)
                mdoc->meta.date = mandoc_strdup("");
        else
                mdoc->meta.date = mandoc_normdate(n->child, n);
}

static void
post_dt(POST_ARGS)
{
        struct roff_node *nn, *n;
        const char       *cp;
        char             *p;

        n = mdoc->last;
        n->flags |= NODE_NOPRT;

        if (mdoc->flags & MDOC_PBODY) {
                mandoc_msg(MANDOCERR_DT_LATE, n->line, n->pos, "Dt");
                return;
        }

        if (mdoc->meta.title != NULL)
                mandoc_msg(MANDOCERR_PROLOG_REP, n->line, n->pos, "Dt");
        else if (mdoc->meta.os != NULL)
                mandoc_msg(MANDOCERR_PROLOG_ORDER,
                    n->line, n->pos, "Dt after Os");

        free(mdoc->meta.title);
        free(mdoc->meta.msec);
        free(mdoc->meta.vol);
        free(mdoc->meta.arch);

        mdoc->meta.title = NULL;
        mdoc->meta.msec = NULL;
        mdoc->meta.vol = NULL;
        mdoc->meta.arch = NULL;

        /* Mandatory first argument: title. */

        nn = n->child;
        if (nn == NULL || *nn->string == '\0') {
                mandoc_msg(MANDOCERR_DT_NOTITLE, n->line, n->pos, "Dt");
                mdoc->meta.title = mandoc_strdup("UNTITLED");
        } else {
                mdoc->meta.title = mandoc_strdup(nn->string);

                /* Check that all characters are uppercase. */

                for (p = nn->string; *p != '\0'; p++)
                        if (islower((unsigned char)*p)) {
                                mandoc_msg(MANDOCERR_TITLE_CASE, nn->line,
                                    nn->pos + (int)(p - nn->string),
                                    "Dt %s", nn->string);
                                break;
                        }
        }

        /* Mandatory second argument: section. */

        if (nn != NULL)
                nn = nn->next;

        if (nn == NULL) {
                mandoc_msg(MANDOCERR_MSEC_MISSING, n->line, n->pos,
                    "Dt %s", mdoc->meta.title);
                mdoc->meta.vol = mandoc_strdup("LOCAL");
                return;  /* msec and arch remain NULL. */
        }

        mdoc->meta.msec = mandoc_strdup(nn->string);

        /* Infer volume title from section number. */

        cp = mandoc_a2msec(nn->string);
        if (cp == NULL) {
                mandoc_msg(MANDOCERR_MSEC_BAD,
                    nn->line, nn->pos, "Dt ... %s", nn->string);
                mdoc->meta.vol = mandoc_strdup(nn->string);
        } else {
                mdoc->meta.vol = mandoc_strdup(cp);
                if (mdoc->filesec != '\0' &&
                    mdoc->filesec != *nn->string &&
                    *nn->string >= '1' && *nn->string <= '9')
                        mandoc_msg(MANDOCERR_MSEC_FILE, nn->line, nn->pos,
                            "*.%c vs Dt ... %c", mdoc->filesec, *nn->string);
        }

        /* Optional third argument: architecture. */

        if ((nn = nn->next) == NULL)
                return;

        for (p = nn->string; *p != '\0'; p++)
                *p = tolower((unsigned char)*p);
        mdoc->meta.arch = mandoc_strdup(nn->string);

        /* Ignore fourth and later arguments. */

        if ((nn = nn->next) != NULL)
                mandoc_msg(MANDOCERR_ARG_EXCESS,
                    nn->line, nn->pos, "Dt ... %s", nn->string);
}

static void
post_bx(POST_ARGS)
{
        struct roff_node        *n, *nch;
        const char              *macro;

        post_delim_nb(mdoc);

        n = mdoc->last;
        nch = n->child;

        if (nch != NULL) {
                macro = !strcmp(nch->string, "Open") ? "Ox" :
                    !strcmp(nch->string, "Net") ? "Nx" :
                    !strcmp(nch->string, "Free") ? "Fx" :
                    !strcmp(nch->string, "DragonFly") ? "Dx" : NULL;
                if (macro != NULL)
                        mandoc_msg(MANDOCERR_BX,
                            n->line, n->pos, "%s", macro);
                mdoc->last = nch;
                nch = nch->next;
                mdoc->next = ROFF_NEXT_SIBLING;
                roff_elem_alloc(mdoc, n->line, n->pos, MDOC_Ns);
                mdoc->last->flags |= NODE_NOSRC;
                mdoc->next = ROFF_NEXT_SIBLING;
        } else
                mdoc->next = ROFF_NEXT_CHILD;
        roff_word_alloc(mdoc, n->line, n->pos, "BSD");
        mdoc->last->flags |= NODE_NOSRC;

        if (nch == NULL) {
                mdoc->last = n;
                return;
        }

        roff_elem_alloc(mdoc, n->line, n->pos, MDOC_Ns);
        mdoc->last->flags |= NODE_NOSRC;
        mdoc->next = ROFF_NEXT_SIBLING;
        roff_word_alloc(mdoc, n->line, n->pos, "-");
        mdoc->last->flags |= NODE_NOSRC;
        roff_elem_alloc(mdoc, n->line, n->pos, MDOC_Ns);
        mdoc->last->flags |= NODE_NOSRC;
        mdoc->last = n;

        /*
         * Make `Bx's second argument always start with an uppercase
         * letter.  Groff checks if it's an "accepted" term, but we just
         * uppercase blindly.
         */

        *nch->string = (char)toupper((unsigned char)*nch->string);
}

static void
post_os(POST_ARGS)
{
#ifndef OSNAME
        struct utsname    utsname;
        static char      *defbuf;
#endif
        struct roff_node *n;

        n = mdoc->last;
        n->flags |= NODE_NOPRT;

        if (mdoc->meta.os != NULL)
                mandoc_msg(MANDOCERR_PROLOG_REP, n->line, n->pos, "Os");
        else if (mdoc->flags & MDOC_PBODY)
                mandoc_msg(MANDOCERR_PROLOG_LATE, n->line, n->pos, "Os");

        post_delim(mdoc);

        /*
         * Set the operating system by way of the `Os' macro.
         * The order of precedence is:
         * 1. the argument of the `Os' macro, unless empty
         * 2. the -Ios=foo command line argument, if provided
         * 3. -DOSNAME="\"foo\"", if provided during compilation
         * 4. "sysname release" from uname(2)
         */

        free(mdoc->meta.os);
        mdoc->meta.os = NULL;
        deroff(&mdoc->meta.os, n);
        if (mdoc->meta.os)
                goto out;

        if (mdoc->os_s != NULL) {
                mdoc->meta.os = mandoc_strdup(mdoc->os_s);
                goto out;
        }

#ifdef OSNAME
        mdoc->meta.os = mandoc_strdup(OSNAME);
#else /*!OSNAME */
        if (defbuf == NULL) {
                if (uname(&utsname) == -1) {
                        mandoc_msg(MANDOCERR_OS_UNAME, n->line, n->pos, "Os");
                        defbuf = mandoc_strdup("UNKNOWN");
                } else
                        mandoc_asprintf(&defbuf, "%s %s",
                            utsname.sysname, utsname.release);
        }
        mdoc->meta.os = mandoc_strdup(defbuf);
#endif /*!OSNAME*/

out:
        if (mdoc->meta.os_e == MANDOC_OS_OTHER) {
                if (strstr(mdoc->meta.os, "OpenBSD") != NULL)
                        mdoc->meta.os_e = MANDOC_OS_OPENBSD;
                else if (strstr(mdoc->meta.os, "NetBSD") != NULL)
                        mdoc->meta.os_e = MANDOC_OS_NETBSD;
        }

        /*
         * This is the earliest point where we can check
         * Mdocdate conventions because we don't know
         * the operating system earlier.
         */

        if (n->child != NULL)
                mandoc_msg(MANDOCERR_OS_ARG, n->child->line, n->child->pos,
                    "Os %s (%s)", n->child->string,
                    mdoc->meta.os_e == MANDOC_OS_OPENBSD ?
                    "OpenBSD" : "NetBSD");

        while (n->tok != MDOC_Dd)
                if ((n = n->prev) == NULL)
                        return;
        if ((n = n->child) == NULL)
                return;
        if (strncmp(n->string, "$" "Mdocdate", 9)) {
                if (mdoc->meta.os_e == MANDOC_OS_OPENBSD)
                        mandoc_msg(MANDOCERR_MDOCDATE_MISSING, n->line,
                            n->pos, "Dd %s (OpenBSD)", n->string);
        } else {
                if (mdoc->meta.os_e == MANDOC_OS_NETBSD)
                        mandoc_msg(MANDOCERR_MDOCDATE, n->line,
                            n->pos, "Dd %s (NetBSD)", n->string);
        }
}

enum roff_sec
mdoc_a2sec(const char *p)
{
        int              i;

        for (i = 0; i < (int)SEC__MAX; i++)
                if (secnames[i] && 0 == strcmp(p, secnames[i]))
                        return (enum roff_sec)i;

        return SEC_CUSTOM;
}

static size_t
macro2len(enum roff_tok macro)
{

        switch (macro) {
        case MDOC_Ad:
                return 12;
        case MDOC_Ao:
                return 12;
        case MDOC_An:
                return 12;
        case MDOC_Aq:
                return 12;
        case MDOC_Ar:
                return 12;
        case MDOC_Bo:
                return 12;
        case MDOC_Bq:
                return 12;
        case MDOC_Cd:
                return 12;
        case MDOC_Cm:
                return 10;
        case MDOC_Do:
                return 10;
        case MDOC_Dq:
                return 12;
        case MDOC_Dv:
                return 12;
        case MDOC_Eo:
                return 12;
        case MDOC_Em:
                return 10;
        case MDOC_Er:
                return 17;
        case MDOC_Ev:
                return 15;
        case MDOC_Fa:
                return 12;
        case MDOC_Fl:
                return 10;
        case MDOC_Fo:
                return 16;
        case MDOC_Fn:
                return 16;
        case MDOC_Ic:
                return 10;
        case MDOC_Li:
                return 16;
        case MDOC_Ms:
                return 6;
        case MDOC_Nm:
                return 10;
        case MDOC_No:
                return 12;
        case MDOC_Oo:
                return 10;
        case MDOC_Op:
                return 14;
        case MDOC_Pa:
                return 32;
        case MDOC_Pf:
                return 12;
        case MDOC_Po:
                return 12;
        case MDOC_Pq:
                return 12;
        case MDOC_Ql:
                return 16;
        case MDOC_Qo:
                return 12;
        case MDOC_So:
                return 12;
        case MDOC_Sq:
                return 12;
        case MDOC_Sy:
                return 6;
        case MDOC_Sx:
                return 16;
        case MDOC_Tn:
                return 10;
        case MDOC_Va:
                return 12;
        case MDOC_Vt:
                return 12;
        case MDOC_Xr:
                return 10;
        default:
                break;
        };
        return 0;
}