StdLib/BsdSocketLib/ns_print.c

/*
 * Copyright (c) 1996, 1998 by Internet Software Consortium.
 *
 * 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM 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.
 */

/*
 * Portions copyright (c) 1999, 2000
 * Intel Corporation.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *
 *    This product includes software developed by Intel Corporation and
 *    its contributors.
 *
 * 4. Neither the name of Intel Corporation or its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY INTEL CORPORATION AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL INTEL CORPORATION OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef lint
static char rcsid[] = "$Id: ns_print.c,v 1.1.1.1 2003/11/19 01:51:34 kyu3 Exp $";
#endif

/* Import. */

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

#include <netinet/in.h>
#include <arpa/nameser.h>
#include <arpa/inet.h>

#include <assert.h>
#include <errno.h>
#include <resolv.h>
#include <string.h>
#include <ctype.h>

#define SPRINTF(x) (sprintf x)

/* Forward. */

static size_t   prune_origin(const char *name, const char *origin);
static int  charstr(const u_char *rdata, const u_char *edata,
            char **buf, size_t *buflen);
static int  addname(const u_char *msg, size_t msglen,
            const u_char **p, const char *origin,
            char **buf, size_t *buflen);
static void addlen(size_t len, char **buf, size_t *buflen);
static int  addstr(const char *src, size_t len,
               char **buf, size_t *buflen);
static int  addtab(size_t len, size_t target, int spaced,
               char **buf, size_t *buflen);

/* Macros. */

#define T(x) \
    do { \
        if ((ssize_t)(x) < 0) \
            return (-1); \
    } while (0)

/* Public. */

/*
 * int
 * ns_sprintrr(handle, rr, name_ctx, origin, buf, buflen)
 *  Convert an RR to presentation format.
 * return:
 *  Number of characters written to buf, or -1 (check errno).
 */
int
ns_sprintrr(const ns_msg *handle, const ns_rr *rr,
        const char *name_ctx, const char *origin,
        char *buf, size_t buflen)
{
    int n;

    n = ns_sprintrrf(ns_msg_base(*handle), ns_msg_size(*handle),
             ns_rr_name(*rr), ns_rr_class(*rr), ns_rr_type(*rr),
             ns_rr_ttl(*rr), ns_rr_rdata(*rr), ns_rr_rdlen(*rr),
             name_ctx, origin, buf, buflen);
    return (n);
}

/*
 * int
 * ns_sprintrrf(msg, msglen, name, class, type, ttl, rdata, rdlen,
 *         name_ctx, origin, buf, buflen)
 *  Convert the fields of an RR into presentation format.
 * return:
 *  Number of characters written to buf, or -1 (check errno).
 */
int
ns_sprintrrf(const u_char *msg, size_t msglen,
        const char *name, ns_class class, ns_type type,
        u_long ttl, const u_char *rdata, size_t rdlen,
        const char *name_ctx, const char *origin,
        char *buf, size_t buflen)
{
    const char *obuf = buf;
    const u_char *edata = rdata + rdlen;
    int spaced = 0;

    const char *comment;
    char tmp[100];
    int x;
    size_t len;

    static  char base64_key[NS_MD5RSA_MAX_BASE64];
    static  char t[255*3];

    /*
     * Owner.
     */
    if (name_ctx != NULL && strcasecmp(name_ctx, name) == 0) {
        T(addstr("\t\t\t", 3, &buf, &buflen));
    } else {
        len = prune_origin(name, origin);
        if (len == 0) {
            T(addstr("@\t\t\t", 4, &buf, &buflen));
        } else {
            T(addstr(name, len, &buf, &buflen));
            /* Origin not used and no trailing dot? */
            if ((!origin || !origin[0] || name[len] == '\0') &&
                name[len - 1] != '.') {
                T(addstr(".", 1, &buf, &buflen));
                len++;
            }
            T(spaced = addtab(len, 24, spaced, &buf, &buflen));
        }
    }

    /*
     * TTL, Class, Type.
     */
    T(x = ns_format_ttl(ttl, buf, buflen));
    addlen(x, &buf, &buflen);
    len = SPRINTF((tmp, " %s %s", p_class(class), p_type(type)));
    T(addstr(tmp, len, &buf, &buflen));
    T(spaced = addtab(x + len, 16, spaced, &buf, &buflen));

    /*
     * RData.
     */
    switch (type) {
    case ns_t_a:
        if (rdlen != NS_INADDRSZ)
            goto formerr;
        (void) inet_ntop(AF_INET, rdata, buf, (socklen_t)buflen);
        addlen(strlen(buf), &buf, &buflen);
        break;

    case ns_t_cname:
    case ns_t_mb:
    case ns_t_mg:
    case ns_t_mr:
    case ns_t_ns:
    case ns_t_ptr:
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));
        break;

    case ns_t_hinfo:
    case ns_t_isdn:
        /* First word. */
        T(len = charstr(rdata, edata, &buf, &buflen));
        if (len == 0)
            goto formerr;
        rdata += len;
        T(addstr(" ", 1, &buf, &buflen));

        /* Second word. */
        T(len = charstr(rdata, edata, &buf, &buflen));
        if (len == 0)
            goto formerr;
        rdata += len;
        break;

    case ns_t_soa: {
        u_long t;

        /* Server name. */
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));
        T(addstr(" ", 1, &buf, &buflen));

        /* Administrator name. */
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));
        T(addstr(" (\n", 3, &buf, &buflen));
        spaced = 0;

        if ((edata - rdata) != 5*NS_INT32SZ)
            goto formerr;

        /* Serial number. */
        t = ns_get32(rdata);  rdata += NS_INT32SZ;
        T(addstr("\t\t\t\t\t", 5, &buf, &buflen));
        len = SPRINTF((tmp, "%lu", t));
        T(addstr(tmp, len, &buf, &buflen));
        T(spaced = addtab(len, 16, spaced, &buf, &buflen));
        T(addstr("; serial\n", 9, &buf, &buflen));
        spaced = 0;

        /* Refresh interval. */
        t = ns_get32(rdata);  rdata += NS_INT32SZ;
        T(addstr("\t\t\t\t\t", 5, &buf, &buflen));
        T(len = ns_format_ttl(t, buf, buflen));
        addlen(len, &buf, &buflen);
        T(spaced = addtab(len, 16, spaced, &buf, &buflen));
        T(addstr("; refresh\n", 10, &buf, &buflen));
        spaced = 0;

        /* Retry interval. */
        t = ns_get32(rdata);  rdata += NS_INT32SZ;
        T(addstr("\t\t\t\t\t", 5, &buf, &buflen));
        T(len = ns_format_ttl(t, buf, buflen));
        addlen(len, &buf, &buflen);
        T(spaced = addtab(len, 16, spaced, &buf, &buflen));
        T(addstr("; retry\n", 8, &buf, &buflen));
        spaced = 0;

        /* Expiry. */
        t = ns_get32(rdata);  rdata += NS_INT32SZ;
        T(addstr("\t\t\t\t\t", 5, &buf, &buflen));
        T(len = ns_format_ttl(t, buf, buflen));
        addlen(len, &buf, &buflen);
        T(spaced = addtab(len, 16, spaced, &buf, &buflen));
        T(addstr("; expiry\n", 9, &buf, &buflen));
        spaced = 0;

        /* Minimum TTL. */
        t = ns_get32(rdata);  rdata += NS_INT32SZ;
        T(addstr("\t\t\t\t\t", 5, &buf, &buflen));
        T(len = ns_format_ttl(t, buf, buflen));
        addlen(len, &buf, &buflen);
        T(addstr(" )", 2, &buf, &buflen));
        T(spaced = addtab(len, 16, spaced, &buf, &buflen));
        T(addstr("; minimum\n", 10, &buf, &buflen));

        break;
        }

    case ns_t_mx:
    case ns_t_afsdb:
    case ns_t_rt: {
        u_int t;

        if (rdlen < NS_INT16SZ)
            goto formerr;

        /* Priority. */
        t = ns_get16(rdata);
        rdata += NS_INT16SZ;
        len = SPRINTF((tmp, "%u ", t));
        T(addstr(tmp, len, &buf, &buflen));

        /* Target. */
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));

        break;
        }

    case ns_t_px: {
        u_int t;

        if (rdlen < NS_INT16SZ)
            goto formerr;

        /* Priority. */
        t = ns_get16(rdata);
        rdata += NS_INT16SZ;
        len = SPRINTF((tmp, "%u ", t));
        T(addstr(tmp, len, &buf, &buflen));

        /* Name1. */
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));
        T(addstr(" ", 1, &buf, &buflen));

        /* Name2. */
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));

        break;
        }

    case ns_t_x25:
        T(len = charstr(rdata, edata, &buf, &buflen));
        if (len == 0)
            goto formerr;
        rdata += len;
        break;

    case ns_t_txt:
        while (rdata < edata) {
            T(len = charstr(rdata, edata, &buf, &buflen));
            if (len == 0)
                goto formerr;
            rdata += len;
            if (rdata < edata)
                T(addstr(" ", 1, &buf, &buflen));
        }
        break;

    case ns_t_nsap: {

        (void) inet_nsap_ntoa((int)rdlen, rdata, t);
        T(addstr(t, strlen(t), &buf, &buflen));
        break;
        }

    case ns_t_aaaa:
        if (rdlen != NS_IN6ADDRSZ)
            goto formerr;
        (void) inet_ntop(AF_INET6, rdata, buf, (socklen_t)buflen);
        addlen(strlen(buf), &buf, &buflen);
        break;

    case ns_t_loc: {
        /* XXX protocol format checking? */
        (void) loc_ntoa(rdata, t);
        T(addstr(t, strlen(t), &buf, &buflen));
        break;
        }

    case ns_t_naptr: {
        u_int order, preference;

        if (rdlen < 2*NS_INT16SZ)
            goto formerr;

        /* Order, Precedence. */
        order = ns_get16(rdata);    rdata += NS_INT16SZ;
        preference = ns_get16(rdata);   rdata += NS_INT16SZ;
        len = SPRINTF((t, "%u %u ", order, preference));
        T(addstr(t, len, &buf, &buflen));

        /* Flags. */
        T(len = charstr(rdata, edata, &buf, &buflen));
        if (len == 0)
            goto formerr;
        rdata += len;
        T(addstr(" ", 1, &buf, &buflen));

        /* Service. */
        T(len = charstr(rdata, edata, &buf, &buflen));
        if (len == 0)
            goto formerr;
        rdata += len;
        T(addstr(" ", 1, &buf, &buflen));

        /* Regexp. */
        T(len = charstr(rdata, edata, &buf, &buflen));
        if ((ssize_t)len < 0)
            return (-1);
        if (len == 0)
            goto formerr;
        rdata += len;
        T(addstr(" ", 1, &buf, &buflen));

        /* Server. */
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));
        break;
        }

    case ns_t_srv: {
        u_int priority, weight, port;

        if (rdlen < NS_INT16SZ*3)
            goto formerr;

        /* Priority, Weight, Port. */
        priority = ns_get16(rdata);  rdata += NS_INT16SZ;
        weight   = ns_get16(rdata);  rdata += NS_INT16SZ;
        port     = ns_get16(rdata);  rdata += NS_INT16SZ;
        len = SPRINTF((t, "%u %u %u ", priority, weight, port));
        T(addstr(t, len, &buf, &buflen));

        /* Server. */
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));
        break;
        }

    case ns_t_minfo:
    case ns_t_rp:
        /* Name1. */
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));
        T(addstr(" ", 1, &buf, &buflen));

        /* Name2. */
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));

        break;

    case ns_t_wks: {
        int n, lcnt;

        if (rdlen < NS_INT32SZ + 1)
            goto formerr;

        /* Address. */
        (void) inet_ntop(AF_INET, rdata, buf, (socklen_t)buflen);
        addlen(strlen(buf), &buf, &buflen);
        rdata += NS_INADDRSZ;

        /* Protocol. */
        len = SPRINTF((tmp, " %u ( ", *rdata));
        T(addstr(tmp, len, &buf, &buflen));
        rdata += NS_INT8SZ;

        /* Bit map. */
        n = 0;
        lcnt = 0;
        while (rdata < edata) {
            u_int c = *rdata++;
            do {
                if (c & 0200) {
                    if (lcnt == 0) {
                        T(addstr("\n\t\t\t\t", 5,
                             &buf, &buflen));
                        lcnt = 10;
                        spaced = 0;
                    }
                    len = SPRINTF((tmp, "%d ", n));
                    T(addstr(tmp, len, &buf, &buflen));
                    lcnt--;
                }
                c <<= 1;
            } while (++n & 07);
        }
        T(addstr(")", 1, &buf, &buflen));

        break;
        }

    case ns_t_key: {
        u_int keyflags, protocol, algorithm;
        const char *leader;
        int n;

        if (rdlen < NS_INT16SZ + NS_INT8SZ + NS_INT8SZ)
            goto formerr;

        /* Key flags, Protocol, Algorithm. */
        keyflags = ns_get16(rdata);  rdata += NS_INT16SZ;
        protocol = *rdata++;
        algorithm = *rdata++;
        len = SPRINTF((tmp, "0x%04x %u %u",
                   keyflags, protocol, algorithm));
        T(addstr(tmp, len, &buf, &buflen));

        /* Public key data. */
        len = b64_ntop(rdata, edata - rdata,
                   base64_key, sizeof base64_key);
        if ((ssize_t)len < 0)
            goto formerr;
        if (len > 15) {
            T(addstr(" (", 2, &buf, &buflen));
            leader = "\n\t\t";
            spaced = 0;
        } else
            leader = " ";
        for (n = 0; n < (int)len; n += 48) {
            T(addstr(leader, strlen(leader), &buf, &buflen));
            T(addstr(base64_key + n, MIN(len - n, 48),
                 &buf, &buflen));
        }
        if (len > 15)
            T(addstr(" )", 2, &buf, &buflen));

        break;
        }

    case ns_t_sig: {
        u_int type, algorithm, labels, footprint;
        const char *leader;
        u_long t;
        int n;

        if (rdlen < 22)
            goto formerr;

        /* Type covered, Algorithm, Label count, Original TTL. */
            type = ns_get16(rdata);  rdata += NS_INT16SZ;
        algorithm = *rdata++;
        labels = *rdata++;
        t = ns_get32(rdata);  rdata += NS_INT32SZ;
        len = SPRINTF((tmp, " %s %d %lu ",
                   p_type((int)type), algorithm, t));
        T(addstr(tmp, len, &buf, &buflen));
        if (labels != (u_int)dn_count_labels(name))
            goto formerr;

        /* Signature expiry. */
        t = ns_get32(rdata);  rdata += NS_INT32SZ;
        len = SPRINTF((tmp, "%s ", p_secstodate(t)));
        T(addstr(tmp, len, &buf, &buflen));

        /* Time signed. */
        t = ns_get32(rdata);  rdata += NS_INT32SZ;
        len = SPRINTF((tmp, "%s ", p_secstodate(t)));
        T(addstr(tmp, len, &buf, &buflen));

        /* Signature Footprint. */
        footprint = ns_get16(rdata);  rdata += NS_INT16SZ;
        len = SPRINTF((tmp, "%u ", footprint));
        T(addstr(tmp, len, &buf, &buflen));

        /* Signer's name. */
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));

        /* Signature. */
        len = b64_ntop(rdata, edata - rdata,
                   base64_key, sizeof base64_key);
        if (len > 15) {
            T(addstr(" (", 2, &buf, &buflen));
            leader = "\n\t\t";
            spaced = 0;
        } else
            leader = " ";
        if ((ssize_t)len < 0)
            goto formerr;
        for (n = 0; n < (int)len; n += 48) {
            T(addstr(leader, strlen(leader), &buf, &buflen));
            T(addstr(base64_key + n, MIN(len - n, 48),
                 &buf, &buflen));
        }
        if (len > 15)
            T(addstr(" )", 2, &buf, &buflen));

        break;
        }

    case ns_t_nxt: {
        int n, c;

        /* Next domain name. */
        T(addname(msg, msglen, &rdata, origin, &buf, &buflen));

        /* Type bit map. */
        n = (int)(edata - rdata);
        for (c = 0; c < n*8; c++)
            if (NS_NXT_BIT_ISSET(c, rdata)) {
                len = SPRINTF((tmp, " %s", p_type(c)));
                T(addstr(tmp, len, &buf, &buflen));
            }
        break;
        }

    default:
        comment = "unknown RR type";
        goto hexify;
    }
    return ((int)(buf - obuf));
 formerr:
    comment = "RR format error";
 hexify: {
    int n, m;
    char *p;

    len = SPRINTF((tmp, "\\#(\t\t; %s", comment));
    T(addstr(tmp, len, &buf, &buflen));
    while (rdata < edata) {
        p = tmp;
        p += SPRINTF((p, "\n\t"));
        spaced = 0;
        n = MIN(16, (int)(edata - rdata));
        for (m = 0; m < n; m++)
            p += SPRINTF((p, "%02x ", rdata[m]));
        T(addstr(tmp, (u_int)(p - tmp), &buf, &buflen));
        if (n < 16) {
            T(addstr(")", 1, &buf, &buflen));
            T(addtab((u_int)(p - tmp) + 1, 48, spaced, &buf, &buflen));
        }
        p = tmp;
        p += SPRINTF((p, "; "));
        for (m = 0; m < n; m++)
            *p++ = (isascii(rdata[m]) && isprint(rdata[m]))
                ? rdata[m]
                : '.';
        T(addstr(tmp, (u_int)(p - tmp), &buf, &buflen));
        rdata += n;
    }
    return ((int)(buf - obuf));
    }
}

/* Private. */

/*
 * size_t
 * prune_origin(name, origin)
 *  Find out if the name is at or under the current origin.
 * return:
 *  Number of characters in name before start of origin,
 *  or length of name if origin does not match.
 * notes:
 *  This function should share code with samedomain().
 */
static size_t
prune_origin(const char *name, const char *origin) {
    const char *oname = name;

    while (*name != '\0') {
        if (origin != NULL && strcasecmp(name, origin) == 0)
            return ((size_t)(name - oname) - (name > oname));
        while (*name != '\0') {
            if (*name == '\\') {
                name++;
                /* XXX need to handle \nnn form. */
                if (*name == '\0')
                    break;
            } else if (*name == '.') {
                name++;
                break;
            }
            name++;
        }
    }
    return ((size_t)(name - oname));
}

/*
 * int
 * charstr(rdata, edata, buf, buflen)
 *  Format a <character-string> into the presentation buffer.
 * return:
 *  Number of rdata octets consumed
 *  0 for protocol format error
 *  -1 for output buffer error
 * side effects:
 *  buffer is advanced on success.
 */
static int
charstr(const u_char *rdata, const u_char *edata, char **buf, size_t *buflen) {
    const u_char *odata = rdata;
    size_t save_buflen = *buflen;
    char *save_buf = *buf;

    if (addstr("\"", 1, buf, buflen) < 0)
        goto enospc;
    if (rdata < edata) {
        int n = *rdata;

        if (rdata + 1 + n <= edata) {
            rdata++;
            while (n-- > 0) {
                if (strchr("\n\"\\", *rdata) != NULL)
                    if (addstr("\\", 1, buf, buflen) < 0)
                        goto enospc;
                if (addstr((const char *)rdata, 1,
                       buf, buflen) < 0)
                    goto enospc;
                rdata++;
            }
        }
    }
    if (addstr("\"", 1, buf, buflen) < 0)
        goto enospc;
    return ((int)(rdata - odata));
 enospc:
    errno = ENOSPC;
    *buf = save_buf;
    *buflen = save_buflen;
    return (-1);
}

static int
addname(const u_char *msg, size_t msglen,
    const u_char **pp, const char *origin,
    char **buf, size_t *buflen)
{
    size_t newlen, save_buflen = *buflen;
    char *save_buf = *buf;
    int n;

    n = dn_expand(msg, msg + msglen, *pp, *buf, (int)(*buflen));
    if (n < 0)
        goto enospc;    /* Guess. */
    newlen = prune_origin(*buf, origin);
    if ((origin == NULL || origin[0] == '\0' || (*buf)[newlen] == '\0') &&
        (newlen == 0 || (*buf)[newlen - 1] != '.')) {
        /* No trailing dot. */
        if (newlen + 2 > *buflen)
            goto enospc;    /* No room for ".\0". */
        (*buf)[newlen++] = '.';
        (*buf)[newlen] = '\0';
    }
    if (newlen == 0) {
        /* Use "@" instead of name. */
        if (newlen + 2 > *buflen)
            goto enospc;        /* No room for "@\0". */
        (*buf)[newlen++] = '@';
        (*buf)[newlen] = '\0';
    }
    *pp += n;
    addlen(newlen, buf, buflen);
    **buf = '\0';
    return ((int)newlen);
 enospc:
    errno = ENOSPC;
    *buf = save_buf;
    *buflen = save_buflen;
    return (-1);
}

static void
addlen(size_t len, char **buf, size_t *buflen) {
    assert(len <= *buflen);
    *buf += len;
    *buflen -= len;
}

static int
addstr(const char *src, size_t len, char **buf, size_t *buflen) {
    if (len > *buflen) {
        errno = ENOSPC;
        return (-1);
    }
    memcpy(*buf, src, len);
    addlen(len, buf, buflen);
    **buf = '\0';
    return (0);
}

static int
addtab(size_t len, size_t target, int spaced, char **buf, size_t *buflen) {
    size_t save_buflen = *buflen;
    char *save_buf = *buf;
    int t;

    if (spaced || len >= target - 1) {
        T(addstr("  ", 2, buf, buflen));
        spaced = 1;
    } else {
        for (t = (int)(target - len - 1) / 8; t >= 0; t--)
            if (addstr("\t", 1, buf, buflen) < 0) {
                *buflen = save_buflen;
                *buf = save_buf;
                return (-1);
            }
        spaced = 0;
    }
    return (spaced);
}