cmd/mandoc/roff.c

	roff.c revision 698f87a48e2e945bfe5493ce168e0d0ae1cedd5c
/*  $Id: roff.c,v 1.189 2013/12/30 18:44:06 schwarze Exp $ */
/*
 * Copyright (c) 2010, 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
 * Copyright (c) 2010, 2011, 2012, 2013 Ingo Schwarze <schwarze@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

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

#include "mandoc.h"
#include "libroff.h"
#include "libmandoc.h"

/* Maximum number of nested if-else conditionals. */
#define RSTACK_MAX  128

/* Maximum number of string expansions per line, to break infinite loops. */
#define EXPAND_LIMIT    1000

enum    rofft {
    ROFF_ad,
    ROFF_am,
    ROFF_ami,
    ROFF_am1,
    ROFF_cc,
    ROFF_de,
    ROFF_dei,
    ROFF_de1,
    ROFF_ds,
    ROFF_el,
    ROFF_fam,
    ROFF_hw,
    ROFF_hy,
    ROFF_ie,
    ROFF_if,
    ROFF_ig,
    ROFF_it,
    ROFF_ne,
    ROFF_nh,
    ROFF_nr,
    ROFF_ns,
    ROFF_ps,
    ROFF_rm,
    ROFF_so,
    ROFF_ta,
    ROFF_tr,
    ROFF_Dd,
    ROFF_TH,
    ROFF_TS,
    ROFF_TE,
    ROFF_T_,
    ROFF_EQ,
    ROFF_EN,
    ROFF_cblock,
    ROFF_ccond,
    ROFF_USERDEF,
    ROFF_MAX
};

enum    roffrule {
    ROFFRULE_DENY,
    ROFFRULE_ALLOW
};

/*
 * An incredibly-simple string buffer.
 */
struct  roffstr {
    char        *p; /* nil-terminated buffer */
    size_t       sz; /* saved strlen(p) */
};

/*
 * A key-value roffstr pair as part of a singly-linked list.
 */
struct  roffkv {
    struct roffstr   key;
    struct roffstr   val;
    struct roffkv   *next; /* next in list */
};

/*
 * A single number register as part of a singly-linked list.
 */
struct  roffreg {
    struct roffstr   key;
    int      val;
    struct roffreg  *next;
};

struct  roff {
    enum mparset     parsetype; /* requested parse type */
    struct mparse   *parse; /* parse point */
    struct roffnode *last; /* leaf of stack */
    enum roffrule    rstack[RSTACK_MAX]; /* stack of !`ie' rules */
    char         control; /* control character */
    int      rstackpos; /* position in rstack */
    struct roffreg  *regtab; /* number registers */
    struct roffkv   *strtab; /* user-defined strings & macros */
    struct roffkv   *xmbtab; /* multi-byte trans table (`tr') */
    struct roffstr  *xtab; /* single-byte trans table (`tr') */
    const char  *current_string; /* value of last called user macro */
    struct tbl_node *first_tbl; /* first table parsed */
    struct tbl_node *last_tbl; /* last table parsed */
    struct tbl_node *tbl; /* current table being parsed */
    struct eqn_node *last_eqn; /* last equation parsed */
    struct eqn_node *first_eqn; /* first equation parsed */
    struct eqn_node *eqn; /* current equation being parsed */
};

struct  roffnode {
    enum rofft   tok; /* type of node */
    struct roffnode *parent; /* up one in stack */
    int      line; /* parse line */
    int      col; /* parse col */
    char        *name; /* node name, e.g. macro name */
    char        *end; /* end-rules: custom token */
    int      endspan; /* end-rules: next-line or infty */
    enum roffrule    rule; /* current evaluation rule */
};

#define ROFF_ARGS    struct roff *r, /* parse ctx */ \
             enum rofft tok, /* tok of macro */ \
             char **bufp, /* input buffer */ \
             size_t *szp, /* size of input buffer */ \
             int ln, /* parse line */ \
             int ppos, /* original pos in buffer */ \
             int pos, /* current pos in buffer */ \
             int *offs /* reset offset of buffer data */

typedef enum rofferr (*roffproc)(ROFF_ARGS);

struct  roffmac {
    const char  *name; /* macro name */
    roffproc     proc; /* process new macro */
    roffproc     text; /* process as child text of macro */
    roffproc     sub; /* process as child of macro */
    int      flags;
#define ROFFMAC_STRUCT  (1 << 0) /* always interpret */
    struct roffmac  *next;
};

struct  predef {
    const char  *name; /* predefined input name */
    const char  *str; /* replacement symbol */
};

#define PREDEF(__name, __str) \
    { (__name), (__str) },

static  enum rofft   roffhash_find(const char *, size_t);
static  void         roffhash_init(void);
static  void         roffnode_cleanscope(struct roff *);
static  void         roffnode_pop(struct roff *);
static  void         roffnode_push(struct roff *, enum rofft,
                const char *, int, int);
static  enum rofferr     roff_block(ROFF_ARGS);
static  enum rofferr     roff_block_text(ROFF_ARGS);
static  enum rofferr     roff_block_sub(ROFF_ARGS);
static  enum rofferr     roff_cblock(ROFF_ARGS);
static  enum rofferr     roff_cc(ROFF_ARGS);
static  enum rofferr     roff_ccond(ROFF_ARGS);
static  enum rofferr     roff_cond(ROFF_ARGS);
static  enum rofferr     roff_cond_text(ROFF_ARGS);
static  enum rofferr     roff_cond_sub(ROFF_ARGS);
static  enum rofferr     roff_ds(ROFF_ARGS);
static  enum roffrule    roff_evalcond(const char *, int *);
static  void         roff_free1(struct roff *);
static  void         roff_freereg(struct roffreg *);
static  void         roff_freestr(struct roffkv *);
static  char        *roff_getname(struct roff *, char **, int, int);
static  int      roff_getnum(const char *, int *, int *);
static  int      roff_getop(const char *, int *, char *);
static  int      roff_getregn(const struct roff *,
                const char *, size_t);
static  const char  *roff_getstrn(const struct roff *,
                const char *, size_t);
static  enum rofferr     roff_it(ROFF_ARGS);
static  enum rofferr     roff_line_ignore(ROFF_ARGS);
static  enum rofferr     roff_nr(ROFF_ARGS);
static  void         roff_openeqn(struct roff *, const char *,
                int, int, const char *);
static  enum rofft   roff_parse(struct roff *, const char *, int *);
static  enum rofferr     roff_parsetext(char **, size_t *, int, int *);
static  enum rofferr     roff_res(struct roff *,
                char **, size_t *, int, int);
static  enum rofferr     roff_rm(ROFF_ARGS);
static  void         roff_setstr(struct roff *,
                const char *, const char *, int);
static  void         roff_setstrn(struct roffkv **, const char *,
                size_t, const char *, size_t, int);
static  enum rofferr     roff_so(ROFF_ARGS);
static  enum rofferr     roff_tr(ROFF_ARGS);
static  enum rofferr     roff_Dd(ROFF_ARGS);
static  enum rofferr     roff_TH(ROFF_ARGS);
static  enum rofferr     roff_TE(ROFF_ARGS);
static  enum rofferr     roff_TS(ROFF_ARGS);
static  enum rofferr     roff_EQ(ROFF_ARGS);
static  enum rofferr     roff_EN(ROFF_ARGS);
static  enum rofferr     roff_T_(ROFF_ARGS);
static  enum rofferr     roff_userdef(ROFF_ARGS);

/* See roffhash_find() */

#define ASCII_HI     126
#define ASCII_LO     33
#define HASHWIDTH   (ASCII_HI - ASCII_LO + 1)

static  struct roffmac  *hash[HASHWIDTH];

static  struct roffmac   roffs[ROFF_MAX] = {
    { "ad", roff_line_ignore, NULL, NULL, 0, NULL },
    { "am", roff_block, roff_block_text, roff_block_sub, 0, NULL },
    { "ami", roff_block, roff_block_text, roff_block_sub, 0, NULL },
    { "am1", roff_block, roff_block_text, roff_block_sub, 0, NULL },
    { "cc", roff_cc, NULL, NULL, 0, NULL },
    { "de", roff_block, roff_block_text, roff_block_sub, 0, NULL },
    { "dei", roff_block, roff_block_text, roff_block_sub, 0, NULL },
    { "de1", roff_block, roff_block_text, roff_block_sub, 0, NULL },
    { "ds", roff_ds, NULL, NULL, 0, NULL },
    { "el", roff_cond, roff_cond_text, roff_cond_sub, ROFFMAC_STRUCT, NULL },
    { "fam", roff_line_ignore, NULL, NULL, 0, NULL },
    { "hw", roff_line_ignore, NULL, NULL, 0, NULL },
    { "hy", roff_line_ignore, NULL, NULL, 0, NULL },
    { "ie", roff_cond, roff_cond_text, roff_cond_sub, ROFFMAC_STRUCT, NULL },
    { "if", roff_cond, roff_cond_text, roff_cond_sub, ROFFMAC_STRUCT, NULL },
    { "ig", roff_block, roff_block_text, roff_block_sub, 0, NULL },
    { "it", roff_it, NULL, NULL, 0, NULL },
    { "ne", roff_line_ignore, NULL, NULL, 0, NULL },
    { "nh", roff_line_ignore, NULL, NULL, 0, NULL },
    { "nr", roff_nr, NULL, NULL, 0, NULL },
    { "ns", roff_line_ignore, NULL, NULL, 0, NULL },
    { "ps", roff_line_ignore, NULL, NULL, 0, NULL },
    { "rm", roff_rm, NULL, NULL, 0, NULL },
    { "so", roff_so, NULL, NULL, 0, NULL },
    { "ta", roff_line_ignore, NULL, NULL, 0, NULL },
    { "tr", roff_tr, NULL, NULL, 0, NULL },
    { "Dd", roff_Dd, NULL, NULL, 0, NULL },
    { "TH", roff_TH, NULL, NULL, 0, NULL },
    { "TS", roff_TS, NULL, NULL, 0, NULL },
    { "TE", roff_TE, NULL, NULL, 0, NULL },
    { "T&", roff_T_, NULL, NULL, 0, NULL },
    { "EQ", roff_EQ, NULL, NULL, 0, NULL },
    { "EN", roff_EN, NULL, NULL, 0, NULL },
    { ".", roff_cblock, NULL, NULL, 0, NULL },
    { "\\}", roff_ccond, NULL, NULL, 0, NULL },
    { NULL, roff_userdef, NULL, NULL, 0, NULL },
};

const   char *const __mdoc_reserved[] = {
    "Ac", "Ad", "An", "Ao", "Ap", "Aq", "Ar", "At",
    "Bc", "Bd", "Bf", "Bk", "Bl", "Bo", "Bq",
    "Brc", "Bro", "Brq", "Bsx", "Bt", "Bx",
    "Cd", "Cm", "Db", "Dc", "Dd", "Dl", "Do", "Dq",
    "Ds", "Dt", "Dv", "Dx", "D1",
    "Ec", "Ed", "Ef", "Ek", "El", "Em", "em",
    "En", "Eo", "Eq", "Er", "Es", "Ev", "Ex",
    "Fa", "Fc", "Fd", "Fl", "Fn", "Fo", "Fr", "Ft", "Fx",
    "Hf", "Ic", "In", "It", "Lb", "Li", "Lk", "Lp", "LP",
    "Me", "Ms", "Mt", "Nd", "Nm", "No", "Ns", "Nx",
    "Oc", "Oo", "Op", "Os", "Ot", "Ox",
    "Pa", "Pc", "Pf", "Po", "Pp", "PP", "pp", "Pq",
    "Qc", "Ql", "Qo", "Qq", "Or", "Rd", "Re", "Rs", "Rv",
    "Sc", "Sf", "Sh", "SH", "Sm", "So", "Sq",
    "Ss", "St", "Sx", "Sy",
    "Ta", "Tn", "Ud", "Ux", "Va", "Vt", "Xc", "Xo", "Xr",
    "%A", "%B", "%D", "%I", "%J", "%N", "%O",
    "%P", "%Q", "%R", "%T", "%U", "%V",
    NULL
};

const   char *const __man_reserved[] = {
    "AT", "B", "BI", "BR", "BT", "DE", "DS", "DT",
    "EE", "EN", "EQ", "EX", "HF", "HP", "I", "IB", "IP", "IR",
    "LP", "ME", "MT", "OP", "P", "PD", "PP", "PT",
    "R", "RB", "RE", "RI", "RS", "SB", "SH", "SM", "SS", "SY",
    "TE", "TH", "TP", "TQ", "TS", "T&", "UC", "UE", "UR", "YS",
    NULL
};

/* Array of injected predefined strings. */
#define PREDEFS_MAX  38
static  const struct predef predefs[PREDEFS_MAX] = {
#include "predefs.in"
};

/* See roffhash_find() */
#define ROFF_HASH(p)    (p[0] - ASCII_LO)

static  int  roffit_lines;  /* number of lines to delay */
static  char    *roffit_macro;  /* nil-terminated macro line */

static void
roffhash_init(void)
{
    struct roffmac   *n;
    int       buc, i;

    for (i = 0; i < (int)ROFF_USERDEF; i++) {
        assert(roffs[i].name[0] >= ASCII_LO);
        assert(roffs[i].name[0] <= ASCII_HI);

        buc = ROFF_HASH(roffs[i].name);

        if (NULL != (n = hash[buc])) {
            for ( ; n->next; n = n->next)
                /* Do nothing. */ ;
            n->next = &roffs[i];
        } else
            hash[buc] = &roffs[i];
    }
}

/*
 * Look up a roff token by its name.  Returns ROFF_MAX if no macro by
 * the nil-terminated string name could be found.
 */
static enum rofft
roffhash_find(const char *p, size_t s)
{
    int      buc;
    struct roffmac  *n;

    /*
     * libroff has an extremely simple hashtable, for the time
     * being, which simply keys on the first character, which must
     * be printable, then walks a chain.  It works well enough until
     * optimised.
     */

    if (p[0] < ASCII_LO || p[0] > ASCII_HI)
        return(ROFF_MAX);

    buc = ROFF_HASH(p);

    if (NULL == (n = hash[buc]))
        return(ROFF_MAX);
    for ( ; n; n = n->next)
        if (0 == strncmp(n->name, p, s) && '\0' == n->name[(int)s])
            return((enum rofft)(n - roffs));

    return(ROFF_MAX);
}


/*
 * Pop the current node off of the stack of roff instructions currently
 * pending.
 */
static void
roffnode_pop(struct roff *r)
{
    struct roffnode *p;

    assert(r->last);
    p = r->last;

    r->last = r->last->parent;
    free(p->name);
    free(p->end);
    free(p);
}


/*
 * Push a roff node onto the instruction stack.  This must later be
 * removed with roffnode_pop().
 */
static void
roffnode_push(struct roff *r, enum rofft tok, const char *name,
        int line, int col)
{
    struct roffnode *p;

    p = mandoc_calloc(1, sizeof(struct roffnode));
    p->tok = tok;
    if (name)
        p->name = mandoc_strdup(name);
    p->parent = r->last;
    p->line = line;
    p->col = col;
    p->rule = p->parent ? p->parent->rule : ROFFRULE_DENY;

    r->last = p;
}


static void
roff_free1(struct roff *r)
{
    struct tbl_node *tbl;
    struct eqn_node *e;
    int      i;

    while (NULL != (tbl = r->first_tbl)) {
        r->first_tbl = tbl->next;
        tbl_free(tbl);
    }

    r->first_tbl = r->last_tbl = r->tbl = NULL;

    while (NULL != (e = r->first_eqn)) {
        r->first_eqn = e->next;
        eqn_free(e);
    }

    r->first_eqn = r->last_eqn = r->eqn = NULL;

    while (r->last)
        roffnode_pop(r);

    roff_freestr(r->strtab);
    roff_freestr(r->xmbtab);

    r->strtab = r->xmbtab = NULL;

    roff_freereg(r->regtab);

    r->regtab = NULL;

    if (r->xtab)
        for (i = 0; i < 128; i++)
            free(r->xtab[i].p);

    free(r->xtab);
    r->xtab = NULL;
}

void
roff_reset(struct roff *r)
{
    int      i;

    roff_free1(r);

    r->control = 0;

    for (i = 0; i < PREDEFS_MAX; i++)
        roff_setstr(r, predefs[i].name, predefs[i].str, 0);
}


void
roff_free(struct roff *r)
{

    roff_free1(r);
    free(r);
}


struct roff *
roff_alloc(enum mparset type, struct mparse *parse)
{
    struct roff *r;
    int      i;

    r = mandoc_calloc(1, sizeof(struct roff));
    r->parsetype = type;
    r->parse = parse;
    r->rstackpos = -1;

    roffhash_init();

    for (i = 0; i < PREDEFS_MAX; i++)
        roff_setstr(r, predefs[i].name, predefs[i].str, 0);

    return(r);
}

/*
 * In the current line, expand user-defined strings ("\*")
 * and references to number registers ("\n").
 * Also check the syntax of other escape sequences.
 */
static enum rofferr
roff_res(struct roff *r, char **bufp, size_t *szp, int ln, int pos)
{
    char         ubuf[12]; /* buffer to print the number */
    const char  *stesc; /* start of an escape sequence ('\\') */
    const char  *stnam; /* start of the name, after "[(*" */
    const char  *cp;    /* end of the name, e.g. before ']' */
    const char  *res;   /* the string to be substituted */
    char        *nbuf;  /* new buffer to copy bufp to */
    size_t       nsz;   /* size of the new buffer */
    size_t       maxl;  /* expected length of the escape name */
    size_t       naml;  /* actual length of the escape name */
    int      expand_count;  /* to avoid infinite loops */

    expand_count = 0;

again:
    cp = *bufp + pos;
    while (NULL != (cp = strchr(cp, '\\'))) {
        stesc = cp++;

        /*
         * The second character must be an asterisk or an n.
         * If it isn't, skip it anyway:  It is escaped,
         * so it can't start another escape sequence.
         */

        if ('\0' == *cp)
            return(ROFF_CONT);

        switch (*cp) {
        case ('*'):
            res = NULL;
            break;
        case ('n'):
            res = ubuf;
            break;
        default:
            if (ESCAPE_ERROR != mandoc_escape(&cp, NULL, NULL))
                continue;
            mandoc_msg
                (MANDOCERR_BADESCAPE, r->parse,
                 ln, (int)(stesc - *bufp), NULL);
            return(ROFF_CONT);
        }

        cp++;

        /*
         * The third character decides the length
         * of the name of the string or register.
         * Save a pointer to the name.
         */

        switch (*cp) {
        case ('\0'):
            return(ROFF_CONT);
        case ('('):
            cp++;
            maxl = 2;
            break;
        case ('['):
            cp++;
            maxl = 0;
            break;
        default:
            maxl = 1;
            break;
        }
        stnam = cp;

        /* Advance to the end of the name. */

        for (naml = 0; 0 == maxl || naml < maxl; naml++, cp++) {
            if ('\0' == *cp) {
                mandoc_msg
                    (MANDOCERR_BADESCAPE,
                     r->parse, ln,
                     (int)(stesc - *bufp), NULL);
                return(ROFF_CONT);
            }
            if (0 == maxl && ']' == *cp)
                break;
        }

        /*
         * Retrieve the replacement string; if it is
         * undefined, resume searching for escapes.
         */

        if (NULL == res)
            res = roff_getstrn(r, stnam, naml);
        else
            snprintf(ubuf, sizeof(ubuf), "%d",
                roff_getregn(r, stnam, naml));

        if (NULL == res) {
            mandoc_msg
                (MANDOCERR_BADESCAPE, r->parse,
                 ln, (int)(stesc - *bufp), NULL);
            res = "";
        }

        /* Replace the escape sequence by the string. */

        pos = stesc - *bufp;

        nsz = *szp + strlen(res) + 1;
        nbuf = mandoc_malloc(nsz);

        strlcpy(nbuf, *bufp, (size_t)(stesc - *bufp + 1));
        strlcat(nbuf, res, nsz);
        strlcat(nbuf, cp + (maxl ? 0 : 1), nsz);

        free(*bufp);

        *bufp = nbuf;
        *szp = nsz;

        if (EXPAND_LIMIT >= ++expand_count)
            goto again;

        /* Just leave the string unexpanded. */
        mandoc_msg(MANDOCERR_ROFFLOOP, r->parse, ln, pos, NULL);
        return(ROFF_IGN);
    }
    return(ROFF_CONT);
}

/*
 * Process text streams:
 * Convert all breakable hyphens into ASCII_HYPH.
 * Decrement and spring input line trap.
 */
static enum rofferr
roff_parsetext(char **bufp, size_t *szp, int pos, int *offs)
{
    size_t       sz;
    const char  *start;
    char        *p;
    int      isz;
    enum mandoc_esc  esc;

    start = p = *bufp + pos;

    while ('\0' != *p) {
        sz = strcspn(p, "-\\");
        p += sz;

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

        if ('\\' == *p) {
            /* Skip over escapes. */
            p++;
            esc = mandoc_escape((const char **)&p, NULL, NULL);
            if (ESCAPE_ERROR == esc)
                break;
            continue;
        } else if (p == start) {
            p++;
            continue;
        }

        if (isalpha((unsigned char)p[-1]) &&
            isalpha((unsigned char)p[1]))
            *p = ASCII_HYPH;
        p++;
    }

    /* Spring the input line trap. */
    if (1 == roffit_lines) {
        isz = asprintf(&p, "%s\n.%s", *bufp, roffit_macro);
        if (-1 == isz) {
            perror(NULL);
            exit((int)MANDOCLEVEL_SYSERR);
        }
        free(*bufp);
        *bufp = p;
        *szp = isz + 1;
        *offs = 0;
        free(roffit_macro);
        roffit_lines = 0;
        return(ROFF_REPARSE);
    } else if (1 < roffit_lines)
        --roffit_lines;
    return(ROFF_CONT);
}

enum rofferr
roff_parseln(struct roff *r, int ln, char **bufp,
        size_t *szp, int pos, int *offs)
{
    enum rofft   t;
    enum rofferr     e;
    int      ppos, ctl;

    /*
     * Run the reserved-word filter only if we have some reserved
     * words to fill in.
     */

    e = roff_res(r, bufp, szp, ln, pos);
    if (ROFF_IGN == e)
        return(e);
    assert(ROFF_CONT == e);

    ppos = pos;
    ctl = roff_getcontrol(r, *bufp, &pos);

    /*
     * First, if a scope is open and we're not a macro, pass the
     * text through the macro's filter.  If a scope isn't open and
     * we're not a macro, just let it through.
     * Finally, if there's an equation scope open, divert it into it
     * no matter our state.
     */

    if (r->last && ! ctl) {
        t = r->last->tok;
        assert(roffs[t].text);
        e = (*roffs[t].text)
            (r, t, bufp, szp, ln, pos, pos, offs);
        assert(ROFF_IGN == e || ROFF_CONT == e);
        if (ROFF_CONT != e)
            return(e);
    }
    if (r->eqn)
        return(eqn_read(&r->eqn, ln, *bufp, ppos, offs));
    if ( ! ctl) {
        if (r->tbl)
            return(tbl_read(r->tbl, ln, *bufp, pos));
        return(roff_parsetext(bufp, szp, pos, offs));
    }

    /*
     * If a scope is open, go to the child handler for that macro,
     * as it may want to preprocess before doing anything with it.
     * Don't do so if an equation is open.
     */

    if (r->last) {
        t = r->last->tok;
        assert(roffs[t].sub);
        return((*roffs[t].sub)
                (r, t, bufp, szp,
                 ln, ppos, pos, offs));
    }

    /*
     * Lastly, as we've no scope open, try to look up and execute
     * the new macro.  If no macro is found, simply return and let
     * the compilers handle it.
     */

    if (ROFF_MAX == (t = roff_parse(r, *bufp, &pos)))
        return(ROFF_CONT);

    assert(roffs[t].proc);
    return((*roffs[t].proc)
            (r, t, bufp, szp,
             ln, ppos, pos, offs));
}


void
roff_endparse(struct roff *r)
{

    if (r->last)
        mandoc_msg(MANDOCERR_SCOPEEXIT, r->parse,
                r->last->line, r->last->col, NULL);

    if (r->eqn) {
        mandoc_msg(MANDOCERR_SCOPEEXIT, r->parse,
                r->eqn->eqn.ln, r->eqn->eqn.pos, NULL);
        eqn_end(&r->eqn);
    }

    if (r->tbl) {
        mandoc_msg(MANDOCERR_SCOPEEXIT, r->parse,
                r->tbl->line, r->tbl->pos, NULL);
        tbl_end(&r->tbl);
    }
}

/*
 * Parse a roff node's type from the input buffer.  This must be in the
 * form of ".foo xxx" in the usual way.
 */
static enum rofft
roff_parse(struct roff *r, const char *buf, int *pos)
{
    const char  *mac;
    size_t       maclen;
    enum rofft   t;

    if ('\0' == buf[*pos] || '"' == buf[*pos] ||
            '\t' == buf[*pos] || ' ' == buf[*pos])
        return(ROFF_MAX);

    /*
     * We stop the macro parse at an escape, tab, space, or nil.
     * However, `\}' is also a valid macro, so make sure we don't
     * clobber it by seeing the `\' as the end of token.
     */

    mac = buf + *pos;
    maclen = strcspn(mac + 1, " \\\t\0") + 1;

    t = (r->current_string = roff_getstrn(r, mac, maclen))
        ? ROFF_USERDEF : roffhash_find(mac, maclen);

    *pos += (int)maclen;

    while (buf[*pos] && ' ' == buf[*pos])
        (*pos)++;

    return(t);
}

/* ARGSUSED */
static enum rofferr
roff_cblock(ROFF_ARGS)
{

    /*
     * A block-close `..' should only be invoked as a child of an
     * ignore macro, otherwise raise a warning and just ignore it.
     */

    if (NULL == r->last) {
        mandoc_msg(MANDOCERR_NOSCOPE, r->parse, ln, ppos, NULL);
        return(ROFF_IGN);
    }

    switch (r->last->tok) {
    case (ROFF_am):
        /* FALLTHROUGH */
    case (ROFF_ami):
        /* FALLTHROUGH */
    case (ROFF_am1):
        /* FALLTHROUGH */
    case (ROFF_de):
        /* ROFF_de1 is remapped to ROFF_de in roff_block(). */
        /* FALLTHROUGH */
    case (ROFF_dei):
        /* FALLTHROUGH */
    case (ROFF_ig):
        break;
    default:
        mandoc_msg(MANDOCERR_NOSCOPE, r->parse, ln, ppos, NULL);
        return(ROFF_IGN);
    }

    if ((*bufp)[pos])
        mandoc_msg(MANDOCERR_ARGSLOST, r->parse, ln, pos, NULL);

    roffnode_pop(r);
    roffnode_cleanscope(r);
    return(ROFF_IGN);

}


static void
roffnode_cleanscope(struct roff *r)
{

    while (r->last) {
        if (--r->last->endspan != 0)
            break;
        roffnode_pop(r);
    }
}


/* ARGSUSED */
static enum rofferr
roff_ccond(ROFF_ARGS)
{

    if (NULL == r->last) {
        mandoc_msg(MANDOCERR_NOSCOPE, r->parse, ln, ppos, NULL);
        return(ROFF_IGN);
    }

    switch (r->last->tok) {
    case (ROFF_el):
        /* FALLTHROUGH */
    case (ROFF_ie):
        /* FALLTHROUGH */
    case (ROFF_if):
        break;
    default:
        mandoc_msg(MANDOCERR_NOSCOPE, r->parse, ln, ppos, NULL);
        return(ROFF_IGN);
    }

    if (r->last->endspan > -1) {
        mandoc_msg(MANDOCERR_NOSCOPE, r->parse, ln, ppos, NULL);
        return(ROFF_IGN);
    }

    if ((*bufp)[pos])
        mandoc_msg(MANDOCERR_ARGSLOST, r->parse, ln, pos, NULL);

    roffnode_pop(r);
    roffnode_cleanscope(r);
    return(ROFF_IGN);
}


/* ARGSUSED */
static enum rofferr
roff_block(ROFF_ARGS)
{
    int     sv;
    size_t      sz;
    char        *name;

    name = NULL;

    if (ROFF_ig != tok) {
        if ('\0' == (*bufp)[pos]) {
            mandoc_msg(MANDOCERR_NOARGS, r->parse, ln, ppos, NULL);
            return(ROFF_IGN);
        }

        /*
         * Re-write `de1', since we don't really care about
         * groff's strange compatibility mode, into `de'.
         */

        if (ROFF_de1 == tok)
            tok = ROFF_de;
        if (ROFF_de == tok)
            name = *bufp + pos;
        else
            mandoc_msg(MANDOCERR_REQUEST, r->parse, ln, ppos,
                roffs[tok].name);

        while ((*bufp)[pos] && ! isspace((unsigned char)(*bufp)[pos]))
            pos++;

        while (isspace((unsigned char)(*bufp)[pos]))
            (*bufp)[pos++] = '\0';
    }

    roffnode_push(r, tok, name, ln, ppos);

    /*
     * At the beginning of a `de' macro, clear the existing string
     * with the same name, if there is one.  New content will be
     * added from roff_block_text() in multiline mode.
     */

    if (ROFF_de == tok)
        roff_setstr(r, name, "", 0);

    if ('\0' == (*bufp)[pos])
        return(ROFF_IGN);

    /* If present, process the custom end-of-line marker. */

    sv = pos;
    while ((*bufp)[pos] && ! isspace((unsigned char)(*bufp)[pos]))
        pos++;

    /*
     * Note: groff does NOT like escape characters in the input.
     * Instead of detecting this, we're just going to let it fly and
     * to hell with it.
     */

    assert(pos > sv);
    sz = (size_t)(pos - sv);

    if (1 == sz && '.' == (*bufp)[sv])
        return(ROFF_IGN);

    r->last->end = mandoc_malloc(sz + 1);

    memcpy(r->last->end, *bufp + sv, sz);
    r->last->end[(int)sz] = '\0';

    if ((*bufp)[pos])
        mandoc_msg(MANDOCERR_ARGSLOST, r->parse, ln, pos, NULL);

    return(ROFF_IGN);
}


/* ARGSUSED */
static enum rofferr
roff_block_sub(ROFF_ARGS)
{
    enum rofft  t;
    int     i, j;

    /*
     * First check whether a custom macro exists at this level.  If
     * it does, then check against it.  This is some of groff's
     * stranger behaviours.  If we encountered a custom end-scope
     * tag and that tag also happens to be a "real" macro, then we
     * need to try interpreting it again as a real macro.  If it's
     * not, then return ignore.  Else continue.
     */

    if (r->last->end) {
        for (i = pos, j = 0; r->last->end[j]; j++, i++)
            if ((*bufp)[i] != r->last->end[j])
                break;

        if ('\0' == r->last->end[j] &&
                ('\0' == (*bufp)[i] ||
                 ' ' == (*bufp)[i] ||
                 '\t' == (*bufp)[i])) {
            roffnode_pop(r);
            roffnode_cleanscope(r);

            while (' ' == (*bufp)[i] || '\t' == (*bufp)[i])
                i++;

            pos = i;
            if (ROFF_MAX != roff_parse(r, *bufp, &pos))
                return(ROFF_RERUN);
            return(ROFF_IGN);
        }
    }

    /*
     * If we have no custom end-query or lookup failed, then try
     * pulling it out of the hashtable.
     */

    t = roff_parse(r, *bufp, &pos);

    /*
     * Macros other than block-end are only significant
     * in `de' blocks; elsewhere, simply throw them away.
     */
    if (ROFF_cblock != t) {
        if (ROFF_de == tok)
            roff_setstr(r, r->last->name, *bufp + ppos, 1);
        return(ROFF_IGN);
    }

    assert(roffs[t].proc);
    return((*roffs[t].proc)(r, t, bufp, szp,
                ln, ppos, pos, offs));
}


/* ARGSUSED */
static enum rofferr
roff_block_text(ROFF_ARGS)
{

    if (ROFF_de == tok)
        roff_setstr(r, r->last->name, *bufp + pos, 1);

    return(ROFF_IGN);
}


/* ARGSUSED */
static enum rofferr
roff_cond_sub(ROFF_ARGS)
{
    enum rofft   t;
    enum roffrule    rr;
    char        *ep;

    rr = r->last->rule;
    roffnode_cleanscope(r);
    t = roff_parse(r, *bufp, &pos);

    /*
     * Fully handle known macros when they are structurally
     * required or when the conditional evaluated to true.
     */

    if ((ROFF_MAX != t) &&
        (ROFF_ccond == t || ROFFRULE_ALLOW == rr ||
         ROFFMAC_STRUCT & roffs[t].flags)) {
        assert(roffs[t].proc);
        return((*roffs[t].proc)(r, t, bufp, szp,
                    ln, ppos, pos, offs));
    }

    /* Always check for the closing delimiter `\}'. */

    ep = &(*bufp)[pos];
    while (NULL != (ep = strchr(ep, '\\'))) {
        if ('}' != *(++ep))
            continue;

        /*
         * If we're at the end of line, then just chop
         * off the \} and resize the buffer.
         * If we aren't, then convert it to spaces.
         */

        if ('\0' == *(ep + 1)) {
            *--ep = '\0';
            *szp -= 2;
        } else
            *(ep - 1) = *ep = ' ';

        roff_ccond(r, ROFF_ccond, bufp, szp,
                ln, pos, pos + 2, offs);
        break;
    }
    return(ROFFRULE_DENY == rr ? ROFF_IGN : ROFF_CONT);
}

/* ARGSUSED */
static enum rofferr
roff_cond_text(ROFF_ARGS)
{
    char        *ep;
    enum roffrule    rr;

    rr = r->last->rule;
    roffnode_cleanscope(r);

    ep = &(*bufp)[pos];
    for ( ; NULL != (ep = strchr(ep, '\\')); ep++) {
        ep++;
        if ('}' != *ep)
            continue;
        *ep = '&';
        roff_ccond(r, ROFF_ccond, bufp, szp,
                ln, pos, pos + 2, offs);
    }
    return(ROFFRULE_DENY == rr ? ROFF_IGN : ROFF_CONT);
}

static int
roff_getnum(const char *v, int *pos, int *res)
{
    int p, n;

    p = *pos;
    n = v[p] == '-';
    if (n)
        p++;

    for (*res = 0; isdigit((unsigned char)v[p]); p++)
        *res += 10 * *res + v[p] - '0';
    if (p == *pos + n)
        return 0;

    if (n)
        *res = -*res;

    *pos = p;
    return 1;
}

static int
roff_getop(const char *v, int *pos, char *res)
{
    int e;

    *res = v[*pos];
    e = v[*pos + 1] == '=';

    switch (*res) {
    case '=':
        break;
    case '>':
        if (e)
            *res = 'g';
        break;
    case '<':
        if (e)
            *res = 'l';
        break;
    default:
        return(0);
    }

    *pos += 1 + e;

    return(*res);
}

static enum roffrule
roff_evalcond(const char *v, int *pos)
{
    int  not, lh, rh;
    char     op;

    switch (v[*pos]) {
    case ('n'):
        (*pos)++;
        return(ROFFRULE_ALLOW);
    case ('e'):
        /* FALLTHROUGH */
    case ('o'):
        /* FALLTHROUGH */
    case ('t'):
        (*pos)++;
        return(ROFFRULE_DENY);
    case ('!'):
        (*pos)++;
        not = 1;
        break;
    default:
        not = 0;
        break;
    }

    if (!roff_getnum(v, pos, &lh))
        return ROFFRULE_DENY;
    if (!roff_getop(v, pos, &op)) {
        if (lh < 0)
            lh = 0;
        goto out;
    }
    if (!roff_getnum(v, pos, &rh))
        return ROFFRULE_DENY;
    switch (op) {
    case 'g':
        lh = lh >= rh;
        break;
    case 'l':
        lh = lh <= rh;
        break;
    case '=':
        lh = lh == rh;
        break;
    case '>':
        lh = lh > rh;
        break;
    case '<':
        lh = lh < rh;
        break;
    default:
        return ROFFRULE_DENY;
    }
out:
    if (not)
        lh = !lh;
    return lh ? ROFFRULE_ALLOW : ROFFRULE_DENY;
}

/* ARGSUSED */
static enum rofferr
roff_line_ignore(ROFF_ARGS)
{

    return(ROFF_IGN);
}

/* ARGSUSED */
static enum rofferr
roff_cond(ROFF_ARGS)
{

    roffnode_push(r, tok, NULL, ln, ppos);

    /*
     * An `.el' has no conditional body: it will consume the value
     * of the current rstack entry set in prior `ie' calls or
     * defaults to DENY.
     *
     * If we're not an `el', however, then evaluate the conditional.
     */

    r->last->rule = ROFF_el == tok ?
        (r->rstackpos < 0 ?
         ROFFRULE_DENY : r->rstack[r->rstackpos--]) :
        roff_evalcond(*bufp, &pos);

    /*
     * An if-else will put the NEGATION of the current evaluated
     * conditional into the stack of rules.
     */

    if (ROFF_ie == tok) {
        if (r->rstackpos == RSTACK_MAX - 1) {
            mandoc_msg(MANDOCERR_MEM,
                r->parse, ln, ppos, NULL);
            return(ROFF_ERR);
        }
        r->rstack[++r->rstackpos] =
            ROFFRULE_DENY == r->last->rule ?
            ROFFRULE_ALLOW : ROFFRULE_DENY;
    }

    /* If the parent has false as its rule, then so do we. */

    if (r->last->parent && ROFFRULE_DENY == r->last->parent->rule)
        r->last->rule = ROFFRULE_DENY;

    /*
     * Determine scope.
     * If there is nothing on the line after the conditional,
     * not even whitespace, use next-line scope.
     */

    if ('\0' == (*bufp)[pos]) {
        r->last->endspan = 2;
        goto out;
    }

    while (' ' == (*bufp)[pos])
        pos++;

    /* An opening brace requests multiline scope. */

    if ('\\' == (*bufp)[pos] && '{' == (*bufp)[pos + 1]) {
        r->last->endspan = -1;
        pos += 2;
        goto out;
    }

    /*
     * Anything else following the conditional causes
     * single-line scope.  Warn if the scope contains
     * nothing but trailing whitespace.
     */

    if ('\0' == (*bufp)[pos])
        mandoc_msg(MANDOCERR_NOARGS, r->parse, ln, ppos, NULL);

    r->last->endspan = 1;

out:
    *offs = pos;
    return(ROFF_RERUN);
}


/* ARGSUSED */
static enum rofferr
roff_ds(ROFF_ARGS)
{
    char        *name, *string;

    /*
     * A symbol is named by the first word following the macro
     * invocation up to a space.  Its value is anything after the
     * name's trailing whitespace and optional double-quote.  Thus,
     *
     *  [.ds foo "bar  "     ]
     *
     * will have `bar  "     ' as its value.
     */

    string = *bufp + pos;
    name = roff_getname(r, &string, ln, pos);
    if ('\0' == *name)
        return(ROFF_IGN);

    /* Read past initial double-quote. */
    if ('"' == *string)
        string++;

    /* The rest is the value. */
    roff_setstr(r, name, string, 0);
    return(ROFF_IGN);
}

void
roff_setreg(struct roff *r, const char *name, int val, char sign)
{
    struct roffreg  *reg;

    /* Search for an existing register with the same name. */
    reg = r->regtab;

    while (reg && strcmp(name, reg->key.p))
        reg = reg->next;

    if (NULL == reg) {
        /* Create a new register. */
        reg = mandoc_malloc(sizeof(struct roffreg));
        reg->key.p = mandoc_strdup(name);
        reg->key.sz = strlen(name);
        reg->val = 0;
        reg->next = r->regtab;
        r->regtab = reg;
    }

    if ('+' == sign)
        reg->val += val;
    else if ('-' == sign)
        reg->val -= val;
    else
        reg->val = val;
}

int
roff_getreg(const struct roff *r, const char *name)
{
    struct roffreg  *reg;

    for (reg = r->regtab; reg; reg = reg->next)
        if (0 == strcmp(name, reg->key.p))
            return(reg->val);

    return(0);
}

static int
roff_getregn(const struct roff *r, const char *name, size_t len)
{
    struct roffreg  *reg;

    for (reg = r->regtab; reg; reg = reg->next)
        if (len == reg->key.sz &&
            0 == strncmp(name, reg->key.p, len))
            return(reg->val);

    return(0);
}

static void
roff_freereg(struct roffreg *reg)
{
    struct roffreg  *old_reg;

    while (NULL != reg) {
        free(reg->key.p);
        old_reg = reg;
        reg = reg->next;
        free(old_reg);
    }
}

/* ARGSUSED */
static enum rofferr
roff_nr(ROFF_ARGS)
{
    const char  *key;
    char        *val;
    size_t       sz;
    int      iv;
    char         sign;

    val = *bufp + pos;
    key = roff_getname(r, &val, ln, pos);

    sign = *val;
    if ('+' == sign || '-' == sign)
        val++;

    sz = strspn(val, "0123456789");
    iv = sz ? mandoc_strntoi(val, sz, 10) : 0;

    roff_setreg(r, key, iv, sign);

    return(ROFF_IGN);
}

/* ARGSUSED */
static enum rofferr
roff_rm(ROFF_ARGS)
{
    const char   *name;
    char         *cp;

    cp = *bufp + pos;
    while ('\0' != *cp) {
        name = roff_getname(r, &cp, ln, (int)(cp - *bufp));
        if ('\0' != *name)
            roff_setstr(r, name, NULL, 0);
    }
    return(ROFF_IGN);
}

/* ARGSUSED */
static enum rofferr
roff_it(ROFF_ARGS)
{
    char        *cp;
    size_t       len;
    int      iv;

    /* Parse the number of lines. */
    cp = *bufp + pos;
    len = strcspn(cp, " \t");
    cp[len] = '\0';
    if ((iv = mandoc_strntoi(cp, len, 10)) <= 0) {
        mandoc_msg(MANDOCERR_NUMERIC, r->parse,
                ln, ppos, *bufp + 1);
        return(ROFF_IGN);
    }
    cp += len + 1;

    /* Arm the input line trap. */
    roffit_lines = iv;
    roffit_macro = mandoc_strdup(cp);
    return(ROFF_IGN);
}

/* ARGSUSED */
static enum rofferr
roff_Dd(ROFF_ARGS)
{
    const char *const   *cp;

    if (MPARSE_MDOC != r->parsetype)
        for (cp = __mdoc_reserved; *cp; cp++)
            roff_setstr(r, *cp, NULL, 0);

    return(ROFF_CONT);
}

/* ARGSUSED */
static enum rofferr
roff_TH(ROFF_ARGS)
{
    const char *const   *cp;

    if (MPARSE_MDOC != r->parsetype)
        for (cp = __man_reserved; *cp; cp++)
            roff_setstr(r, *cp, NULL, 0);

    return(ROFF_CONT);
}

/* ARGSUSED */
static enum rofferr
roff_TE(ROFF_ARGS)
{

    if (NULL == r->tbl)
        mandoc_msg(MANDOCERR_NOSCOPE, r->parse, ln, ppos, NULL);
    else
        tbl_end(&r->tbl);

    return(ROFF_IGN);
}

/* ARGSUSED */
static enum rofferr
roff_T_(ROFF_ARGS)
{

    if (NULL == r->tbl)
        mandoc_msg(MANDOCERR_NOSCOPE, r->parse, ln, ppos, NULL);
    else
        tbl_restart(ppos, ln, r->tbl);

    return(ROFF_IGN);
}

#if 0
static int
roff_closeeqn(struct roff *r)
{

    return(r->eqn && ROFF_EQN == eqn_end(&r->eqn) ? 1 : 0);
}
#endif

static void
roff_openeqn(struct roff *r, const char *name, int line,
        int offs, const char *buf)
{
    struct eqn_node *e;
    int      poff;

    assert(NULL == r->eqn);
    e = eqn_alloc(name, offs, line, r->parse);

    if (r->last_eqn)
        r->last_eqn->next = e;
    else
        r->first_eqn = r->last_eqn = e;

    r->eqn = r->last_eqn = e;

    if (buf) {
        poff = 0;
        eqn_read(&r->eqn, line, buf, offs, &poff);
    }
}

/* ARGSUSED */
static enum rofferr
roff_EQ(ROFF_ARGS)
{

    roff_openeqn(r, *bufp + pos, ln, ppos, NULL);
    return(ROFF_IGN);
}

/* ARGSUSED */
static enum rofferr
roff_EN(ROFF_ARGS)
{

    mandoc_msg(MANDOCERR_NOSCOPE, r->parse, ln, ppos, NULL);
    return(ROFF_IGN);
}

/* ARGSUSED */
static enum rofferr
roff_TS(ROFF_ARGS)
{
    struct tbl_node *tbl;

    if (r->tbl) {
        mandoc_msg(MANDOCERR_SCOPEBROKEN, r->parse, ln, ppos, NULL);
        tbl_end(&r->tbl);
    }

    tbl = tbl_alloc(ppos, ln, r->parse);

    if (r->last_tbl)
        r->last_tbl->next = tbl;
    else
        r->first_tbl = r->last_tbl = tbl;

    r->tbl = r->last_tbl = tbl;
    return(ROFF_IGN);
}

/* ARGSUSED */
static enum rofferr
roff_cc(ROFF_ARGS)
{
    const char  *p;

    p = *bufp + pos;

    if ('\0' == *p || '.' == (r->control = *p++))
        r->control = 0;

    if ('\0' != *p)
        mandoc_msg(MANDOCERR_ARGCOUNT, r->parse, ln, ppos, NULL);

    return(ROFF_IGN);
}

/* ARGSUSED */
static enum rofferr
roff_tr(ROFF_ARGS)
{
    const char  *p, *first, *second;
    size_t       fsz, ssz;
    enum mandoc_esc  esc;

    p = *bufp + pos;

    if ('\0' == *p) {
        mandoc_msg(MANDOCERR_ARGCOUNT, r->parse, ln, ppos, NULL);
        return(ROFF_IGN);
    }

    while ('\0' != *p) {
        fsz = ssz = 1;

        first = p++;
        if ('\\' == *first) {
            esc = mandoc_escape(&p, NULL, NULL);
            if (ESCAPE_ERROR == esc) {
                mandoc_msg
                    (MANDOCERR_BADESCAPE, r->parse,
                     ln, (int)(p - *bufp), NULL);
                return(ROFF_IGN);
            }
            fsz = (size_t)(p - first);
        }

        second = p++;
        if ('\\' == *second) {
            esc = mandoc_escape(&p, NULL, NULL);
            if (ESCAPE_ERROR == esc) {
                mandoc_msg
                    (MANDOCERR_BADESCAPE, r->parse,
                     ln, (int)(p - *bufp), NULL);
                return(ROFF_IGN);
            }
            ssz = (size_t)(p - second);
        } else if ('\0' == *second) {
            mandoc_msg(MANDOCERR_ARGCOUNT, r->parse,
                    ln, (int)(p - *bufp), NULL);
            second = " ";
            p--;
        }

        if (fsz > 1) {
            roff_setstrn(&r->xmbtab, first,
                    fsz, second, ssz, 0);
            continue;
        }

        if (NULL == r->xtab)
            r->xtab = mandoc_calloc
                (128, sizeof(struct roffstr));

        free(r->xtab[(int)*first].p);
        r->xtab[(int)*first].p = mandoc_strndup(second, ssz);
        r->xtab[(int)*first].sz = ssz;
    }

    return(ROFF_IGN);
}

/* ARGSUSED */
static enum rofferr
roff_so(ROFF_ARGS)
{
    char *name;

    mandoc_msg(MANDOCERR_SO, r->parse, ln, ppos, NULL);

    /*
     * Handle `so'.  Be EXTREMELY careful, as we shouldn't be
     * opening anything that's not in our cwd or anything beneath
     * it.  Thus, explicitly disallow traversing up the file-system
     * or using absolute paths.
     */

    name = *bufp + pos;
    if ('/' == *name || strstr(name, "../") || strstr(name, "/..")) {
        mandoc_msg(MANDOCERR_SOPATH, r->parse, ln, pos, NULL);
        return(ROFF_ERR);
    }

    *offs = pos;
    return(ROFF_SO);
}

/* ARGSUSED */
static enum rofferr
roff_userdef(ROFF_ARGS)
{
    const char   *arg[9];
    char         *cp, *n1, *n2;
    int       i;

    /*
     * Collect pointers to macro argument strings
     * and NUL-terminate them.
     */
    cp = *bufp + pos;
    for (i = 0; i < 9; i++)
        arg[i] = '\0' == *cp ? "" :
            mandoc_getarg(r->parse, &cp, ln, &pos);

    /*
     * Expand macro arguments.
     */
    *szp = 0;
    n1 = cp = mandoc_strdup(r->current_string);
    while (NULL != (cp = strstr(cp, "\\$"))) {
        i = cp[2] - '1';
        if (0 > i || 8 < i) {
            /* Not an argument invocation. */
            cp += 2;
            continue;
        }

        *szp = strlen(n1) - 3 + strlen(arg[i]) + 1;
        n2 = mandoc_malloc(*szp);

        strlcpy(n2, n1, (size_t)(cp - n1 + 1));
        strlcat(n2, arg[i], *szp);
        strlcat(n2, cp + 3, *szp);

        cp = n2 + (cp - n1);
        free(n1);
        n1 = n2;
    }

    /*
     * Replace the macro invocation
     * by the expanded macro.
     */
    free(*bufp);
    *bufp = n1;
    if (0 == *szp)
        *szp = strlen(*bufp) + 1;

    return(*szp > 1 && '\n' == (*bufp)[(int)*szp - 2] ?
       ROFF_REPARSE : ROFF_APPEND);
}

static char *
roff_getname(struct roff *r, char **cpp, int ln, int pos)
{
    char     *name, *cp;

    name = *cpp;
    if ('\0' == *name)
        return(name);

    /* Read until end of name. */
    for (cp = name; '\0' != *cp && ' ' != *cp; cp++) {
        if ('\\' != *cp)
            continue;
        cp++;
        if ('\\' == *cp)
            continue;
        mandoc_msg(MANDOCERR_NAMESC, r->parse, ln, pos, NULL);
        *cp = '\0';
        name = cp;
    }

    /* Nil-terminate name. */
    if ('\0' != *cp)
        *(cp++) = '\0';

    /* Read past spaces. */
    while (' ' == *cp)
        cp++;

    *cpp = cp;
    return(name);
}

/*
 * Store *string into the user-defined string called *name.
 * In multiline mode, append to an existing entry and append '\n';
 * else replace the existing entry, if there is one.
 * To clear an existing entry, call with (*r, *name, NULL, 0).
 */
static void
roff_setstr(struct roff *r, const char *name, const char *string,
    int multiline)
{

    roff_setstrn(&r->strtab, name, strlen(name), string,
            string ? strlen(string) : 0, multiline);
}

static void
roff_setstrn(struct roffkv **r, const char *name, size_t namesz,
        const char *string, size_t stringsz, int multiline)
{
    struct roffkv   *n;
    char        *c;
    int      i;
    size_t       oldch, newch;

    /* Search for an existing string with the same name. */
    n = *r;

    while (n && strcmp(name, n->key.p))
        n = n->next;

    if (NULL == n) {
        /* Create a new string table entry. */
        n = mandoc_malloc(sizeof(struct roffkv));
        n->key.p = mandoc_strndup(name, namesz);
        n->key.sz = namesz;
        n->val.p = NULL;
        n->val.sz = 0;
        n->next = *r;
        *r = n;
    } else if (0 == multiline) {
        /* In multiline mode, append; else replace. */
        free(n->val.p);
        n->val.p = NULL;
        n->val.sz = 0;
    }

    if (NULL == string)
        return;

    /*
     * One additional byte for the '\n' in multiline mode,
     * and one for the terminating '\0'.
     */
    newch = stringsz + (multiline ? 2u : 1u);

    if (NULL == n->val.p) {
        n->val.p = mandoc_malloc(newch);
        *n->val.p = '\0';
        oldch = 0;
    } else {
        oldch = n->val.sz;
        n->val.p = mandoc_realloc(n->val.p, oldch + newch);
    }

    /* Skip existing content in the destination buffer. */
    c = n->val.p + (int)oldch;

    /* Append new content to the destination buffer. */
    i = 0;
    while (i < (int)stringsz) {
        /*
         * Rudimentary roff copy mode:
         * Handle escaped backslashes.
         */
        if ('\\' == string[i] && '\\' == string[i + 1])
            i++;
        *c++ = string[i++];
    }

    /* Append terminating bytes. */
    if (multiline)
        *c++ = '\n';

    *c = '\0';
    n->val.sz = (int)(c - n->val.p);
}

static const char *
roff_getstrn(const struct roff *r, const char *name, size_t len)
{
    const struct roffkv *n;

    for (n = r->strtab; n; n = n->next)
        if (0 == strncmp(name, n->key.p, len) &&
                '\0' == n->key.p[(int)len])
            return(n->val.p);

    return(NULL);
}

static void
roff_freestr(struct roffkv *r)
{
    struct roffkv    *n, *nn;

    for (n = r; n; n = nn) {
        free(n->key.p);
        free(n->val.p);
        nn = n->next;
        free(n);
    }
}

const struct tbl_span *
roff_span(const struct roff *r)
{

    return(r->tbl ? tbl_span(r->tbl) : NULL);
}

const struct eqn *
roff_eqn(const struct roff *r)
{

    return(r->last_eqn ? &r->last_eqn->eqn : NULL);
}

/*
 * Duplicate an input string, making the appropriate character
 * conversations (as stipulated by `tr') along the way.
 * Returns a heap-allocated string with all the replacements made.
 */
char *
roff_strdup(const struct roff *r, const char *p)
{
    const struct roffkv *cp;
    char        *res;
    const char  *pp;
    size_t       ssz, sz;
    enum mandoc_esc  esc;

    if (NULL == r->xmbtab && NULL == r->xtab)
        return(mandoc_strdup(p));
    else if ('\0' == *p)
        return(mandoc_strdup(""));

    /*
     * Step through each character looking for term matches
     * (remember that a `tr' can be invoked with an escape, which is
     * a glyph but the escape is multi-character).
     * We only do this if the character hash has been initialised
     * and the string is >0 length.
     */

    res = NULL;
    ssz = 0;

    while ('\0' != *p) {
        if ('\\' != *p && r->xtab && r->xtab[(int)*p].p) {
            sz = r->xtab[(int)*p].sz;
            res = mandoc_realloc(res, ssz + sz + 1);
            memcpy(res + ssz, r->xtab[(int)*p].p, sz);
            ssz += sz;
            p++;
            continue;
        } else if ('\\' != *p) {
            res = mandoc_realloc(res, ssz + 2);
            res[ssz++] = *p++;
            continue;
        }

        /* Search for term matches. */
        for (cp = r->xmbtab; cp; cp = cp->next)
            if (0 == strncmp(p, cp->key.p, cp->key.sz))
                break;

        if (NULL != cp) {
            /*
             * A match has been found.
             * Append the match to the array and move
             * forward by its keysize.
             */
            res = mandoc_realloc
                (res, ssz + cp->val.sz + 1);
            memcpy(res + ssz, cp->val.p, cp->val.sz);
            ssz += cp->val.sz;
            p += (int)cp->key.sz;
            continue;
        }

        /*
         * Handle escapes carefully: we need to copy
         * over just the escape itself, or else we might
         * do replacements within the escape itself.
         * Make sure to pass along the bogus string.
         */
        pp = p++;
        esc = mandoc_escape(&p, NULL, NULL);
        if (ESCAPE_ERROR == esc) {
            sz = strlen(pp);
            res = mandoc_realloc(res, ssz + sz + 1);
            memcpy(res + ssz, pp, sz);
            break;
        }
        /*
         * We bail out on bad escapes.
         * No need to warn: we already did so when
         * roff_res() was called.
         */
        sz = (int)(p - pp);
        res = mandoc_realloc(res, ssz + sz + 1);
        memcpy(res + ssz, pp, sz);
        ssz += sz;
    }

    res[(int)ssz] = '\0';
    return(res);
}

/*
 * Find out whether a line is a macro line or not.
 * If it is, adjust the current position and return one; if it isn't,
 * return zero and don't change the current position.
 * If the control character has been set with `.cc', then let that grain
 * precedence.
 * This is slighly contrary to groff, where using the non-breaking
 * control character when `cc' has been invoked will cause the
 * non-breaking macro contents to be printed verbatim.
 */
int
roff_getcontrol(const struct roff *r, const char *cp, int *ppos)
{
    int     pos;

    pos = *ppos;

    if (0 != r->control && cp[pos] == r->control)
        pos++;
    else if (0 != r->control)
        return(0);
    else if ('\\' == cp[pos] && '.' == cp[pos + 1])
        pos += 2;
    else if ('.' == cp[pos] || '\'' == cp[pos])
        pos++;
    else
        return(0);

    while (' ' == cp[pos] || '\t' == cp[pos])
        pos++;

    *ppos = pos;
    return(1);
}