lib/dns/masterdump.c

	masterdump.c revision 0c27b3fe77ac1d5094ba3521e8142d9e7973133f
/*
 * Copyright (C) 1999-2009, 2011-2016  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

/*! \file */

#include <config.h>

#include <stdlib.h>

#include <isc/event.h>
#include <isc/file.h>
#include <isc/magic.h>
#include <isc/mem.h>
#include <isc/print.h>
#include <isc/stdio.h>
#include <isc/string.h>
#include <isc/task.h>
#include <isc/time.h>
#include <isc/util.h>

#include <dns/db.h>
#include <dns/dbiterator.h>
#include <dns/events.h>
#include <dns/fixedname.h>
#include <dns/lib.h>
#include <dns/log.h>
#include <dns/master.h>
#include <dns/masterdump.h>
#include <dns/ncache.h>
#include <dns/rdata.h>
#include <dns/rdataclass.h>
#include <dns/rdataset.h>
#include <dns/rdatasetiter.h>
#include <dns/rdatatype.h>
#include <dns/result.h>
#include <dns/time.h>
#include <dns/ttl.h>

#define DNS_DCTX_MAGIC      ISC_MAGIC('D', 'c', 't', 'x')
#define DNS_DCTX_VALID(d)   ISC_MAGIC_VALID(d, DNS_DCTX_MAGIC)

#define RETERR(x) do { \
    isc_result_t _r = (x); \
    if (_r != ISC_R_SUCCESS) \
        return (_r); \
    } while (0)

#define CHECK(x) do { \
    if ((x) != ISC_R_SUCCESS) \
        goto cleanup; \
    } while (0)

struct dns_master_style {
    unsigned int flags;     /* DNS_STYLEFLAG_* */
    unsigned int ttl_column;
    unsigned int class_column;
    unsigned int type_column;
    unsigned int rdata_column;
    unsigned int line_length;
    unsigned int tab_width;
    unsigned int split_width;
};

/*%
 * The maximum length of the newline+indentation that is output
 * when inserting a line break in an RR.  This effectively puts an
 * upper limits on the value of "rdata_column", because if it is
 * very large, the tabs and spaces needed to reach it will not fit.
 */
#define DNS_TOTEXT_LINEBREAK_MAXLEN 100

/*%
 * Context structure for a masterfile dump in progress.
 */
typedef struct dns_totext_ctx {
    dns_master_style_t  style;
    isc_boolean_t       class_printed;
    char *          linebreak;
    char            linebreak_buf[DNS_TOTEXT_LINEBREAK_MAXLEN];
    dns_name_t *        origin;
    dns_name_t *        neworigin;
    dns_fixedname_t     origin_fixname;
    isc_uint32_t        current_ttl;
    isc_boolean_t       current_ttl_valid;
} dns_totext_ctx_t;

LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_keyzone = {
    DNS_STYLEFLAG_OMIT_OWNER |
    DNS_STYLEFLAG_OMIT_CLASS |
    DNS_STYLEFLAG_REL_OWNER |
    DNS_STYLEFLAG_REL_DATA |
    DNS_STYLEFLAG_OMIT_TTL |
    DNS_STYLEFLAG_TTL |
    DNS_STYLEFLAG_COMMENT |
    DNS_STYLEFLAG_RRCOMMENT |
    DNS_STYLEFLAG_MULTILINE |
    DNS_STYLEFLAG_KEYDATA,
    24, 24, 24, 32, 80, 8, UINT_MAX
};

LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_default = {
    DNS_STYLEFLAG_OMIT_OWNER |
    DNS_STYLEFLAG_OMIT_CLASS |
    DNS_STYLEFLAG_REL_OWNER |
    DNS_STYLEFLAG_REL_DATA |
    DNS_STYLEFLAG_OMIT_TTL |
    DNS_STYLEFLAG_TTL |
    DNS_STYLEFLAG_COMMENT |
    DNS_STYLEFLAG_RRCOMMENT |
    DNS_STYLEFLAG_MULTILINE,
    24, 24, 24, 32, 80, 8, UINT_MAX
};

LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_full = {
    DNS_STYLEFLAG_COMMENT |
    DNS_STYLEFLAG_RESIGN,
    46, 46, 46, 64, 120, 8, UINT_MAX
};

LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_explicitttl = {
    DNS_STYLEFLAG_OMIT_OWNER |
    DNS_STYLEFLAG_OMIT_CLASS |
    DNS_STYLEFLAG_REL_OWNER |
    DNS_STYLEFLAG_REL_DATA |
    DNS_STYLEFLAG_COMMENT |
    DNS_STYLEFLAG_RRCOMMENT |
    DNS_STYLEFLAG_MULTILINE,
    24, 32, 32, 40, 80, 8, UINT_MAX
};

LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_cache = {
    DNS_STYLEFLAG_OMIT_OWNER |
    DNS_STYLEFLAG_OMIT_CLASS |
    DNS_STYLEFLAG_MULTILINE |
    DNS_STYLEFLAG_RRCOMMENT |
    DNS_STYLEFLAG_TRUST |
    DNS_STYLEFLAG_NCACHE,
    24, 32, 32, 40, 80, 8, UINT_MAX
};

LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_simple = {
    0,
    24, 32, 32, 40, 80, 8, UINT_MAX
};

/*%
 * A style suitable for dns_rdataset_totext().
 */
LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_debug = {
    DNS_STYLEFLAG_REL_OWNER,
    24, 32, 40, 48, 80, 8, UINT_MAX
};

/*%
 * Similar, but indented (i.e., prepended with dns_master_indentstr).
 */
LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_indent = {
    DNS_STYLEFLAG_REL_OWNER |
    DNS_STYLEFLAG_INDENT,
    24, 32, 40, 48, 80, 8, UINT_MAX
};

/*%
 * Similar, but with each line commented out.
 */
LIBDNS_EXTERNAL_DATA const dns_master_style_t
dns_master_style_comment = {
    DNS_STYLEFLAG_REL_OWNER |
    DNS_STYLEFLAG_MULTILINE |
    DNS_STYLEFLAG_RRCOMMENT |
    DNS_STYLEFLAG_COMMENTDATA,
    24, 32, 40, 48, 80, 8, UINT_MAX
};


/*%
 * Default indent string.
 */
LIBDNS_EXTERNAL_DATA const char *dns_master_indentstr = "\t";

#define N_SPACES 10
static char spaces[N_SPACES+1] = "          ";

#define N_TABS 10
static char tabs[N_TABS+1] = "\t\t\t\t\t\t\t\t\t\t";

struct dns_dumpctx {
    unsigned int        magic;
    isc_mem_t       *mctx;
    isc_mutex_t     lock;
    unsigned int        references;
    isc_boolean_t       canceled;
    isc_boolean_t       first;
    isc_boolean_t       do_date;
    isc_stdtime_t       now;
    FILE            *f;
    dns_db_t        *db;
    dns_dbversion_t     *version;
    dns_dbiterator_t    *dbiter;
    dns_totext_ctx_t    tctx;
    isc_task_t      *task;
    dns_dumpdonefunc_t  done;
    void            *done_arg;
    unsigned int        nodes;
    /* dns_master_dumpinc() */
    char            *file;
    char            *tmpfile;
    dns_masterformat_t  format;
    dns_masterrawheader_t   header;
    isc_result_t        (*dumpsets)(isc_mem_t *mctx, dns_name_t *name,
                        dns_rdatasetiter_t *rdsiter,
                        dns_totext_ctx_t *ctx,
                        isc_buffer_t *buffer, FILE *f);
};

#define NXDOMAIN(x) (((x)->attributes & DNS_RDATASETATTR_NXDOMAIN) != 0)

/*%
 * Output tabs and spaces to go from column '*current' to
 * column 'to', and update '*current' to reflect the new
 * current column.
 */
static isc_result_t
indent(unsigned int *current, unsigned int to, int tabwidth,
       isc_buffer_t *target)
{
    isc_region_t r;
    unsigned char *p;
    unsigned int from;
    int ntabs, nspaces, t;

    from = *current;

    if (to < from + 1)
        to = from + 1;

    ntabs = to / tabwidth - from / tabwidth;
    if (ntabs < 0)
        ntabs = 0;

    if (ntabs > 0) {
        isc_buffer_availableregion(target, &r);
        if (r.length < (unsigned) ntabs)
            return (ISC_R_NOSPACE);
        p = r.base;

        t = ntabs;
        while (t) {
            int n = t;
            if (n > N_TABS)
                n = N_TABS;
            memmove(p, tabs, n);
            p += n;
            t -= n;
        }
        isc_buffer_add(target, ntabs);
        from = (to / tabwidth) * tabwidth;
    }

    nspaces = to - from;
    INSIST(nspaces >= 0);

    isc_buffer_availableregion(target, &r);
    if (r.length < (unsigned) nspaces)
        return (ISC_R_NOSPACE);
    p = r.base;

    t = nspaces;
    while (t) {
        int n = t;
        if (n > N_SPACES)
            n = N_SPACES;
        memmove(p, spaces, n);
        p += n;
        t -= n;
    }
    isc_buffer_add(target, nspaces);

    *current = to;
    return (ISC_R_SUCCESS);
}

static isc_result_t
totext_ctx_init(const dns_master_style_t *style, dns_totext_ctx_t *ctx) {
    isc_result_t result;

    REQUIRE(style->tab_width != 0);

    ctx->style = *style;
    ctx->class_printed = ISC_FALSE;

    dns_fixedname_init(&ctx->origin_fixname);

    /*
     * Set up the line break string if needed.
     */
    if ((ctx->style.flags & DNS_STYLEFLAG_MULTILINE) != 0) {
        isc_buffer_t buf;
        isc_region_t r;
        unsigned int col = 0;

        isc_buffer_init(&buf, ctx->linebreak_buf,
                sizeof(ctx->linebreak_buf));

        isc_buffer_availableregion(&buf, &r);
        if (r.length < 1)
            return (DNS_R_TEXTTOOLONG);
        r.base[0] = '\n';
        isc_buffer_add(&buf, 1);

        if ((ctx->style.flags & DNS_STYLEFLAG_INDENT) != 0) {
            unsigned int ilen = strlen(dns_master_indentstr);
            isc_buffer_availableregion(&buf, &r);
            if (r.length < ilen)
                return (DNS_R_TEXTTOOLONG);
            isc_buffer_putmem(&buf,
                (const isc_uint8_t *) dns_master_indentstr,
                (unsigned int)ilen);
        }

        if ((ctx->style.flags & DNS_STYLEFLAG_COMMENTDATA) != 0) {
            isc_buffer_availableregion(&buf, &r);
            if (r.length < 1)
                return (DNS_R_TEXTTOOLONG);
            r.base[0] = ';';
            isc_buffer_add(&buf, 1);
        }

        result = indent(&col, ctx->style.rdata_column,
                ctx->style.tab_width, &buf);
        /*
         * Do not return ISC_R_NOSPACE if the line break string
         * buffer is too small, because that would just make
         * dump_rdataset() retry indefinitely with ever
         * bigger target buffers.  That's a different buffer,
         * so it won't help.  Use DNS_R_TEXTTOOLONG as a substitute.
         */
        if (result == ISC_R_NOSPACE)
            return (DNS_R_TEXTTOOLONG);
        if (result != ISC_R_SUCCESS)
            return (result);

        isc_buffer_availableregion(&buf, &r);
        if (r.length < 1)
            return (DNS_R_TEXTTOOLONG);
        r.base[0] = '\0';
        isc_buffer_add(&buf, 1);
        ctx->linebreak = ctx->linebreak_buf;
    } else {
        ctx->linebreak = NULL;
    }

    ctx->origin = NULL;
    ctx->neworigin = NULL;
    ctx->current_ttl = 0;
    ctx->current_ttl_valid = ISC_FALSE;

    return (ISC_R_SUCCESS);
}

#define INDENT_TO(col) \
    do { \
         if ((result = indent(&column, ctx->style.col, \
                      ctx->style.tab_width, target)) \
             != ISC_R_SUCCESS) \
                return (result); \
    } while (0)


static isc_result_t
str_totext(const char *source, isc_buffer_t *target) {
    unsigned int l;
    isc_region_t region;

    isc_buffer_availableregion(target, &region);
    l = strlen(source);

    if (l > region.length)
        return (ISC_R_NOSPACE);

    memmove(region.base, source, l);
    isc_buffer_add(target, l);
    return (ISC_R_SUCCESS);
}

static isc_result_t
ncache_summary(dns_rdataset_t *rdataset, isc_boolean_t omit_final_dot,
           isc_buffer_t *target)
{
    isc_result_t result = ISC_R_SUCCESS;
    dns_rdataset_t rds;
    dns_name_t name;

    dns_rdataset_init(&rds);
    dns_name_init(&name, NULL);

    do {
        dns_ncache_current(rdataset, &name, &rds);
        for (result = dns_rdataset_first(&rds);
             result == ISC_R_SUCCESS;
             result = dns_rdataset_next(&rds)) {
            CHECK(str_totext("; ", target));
            CHECK(dns_name_totext(&name, omit_final_dot, target));
            CHECK(str_totext(" ", target));
            CHECK(dns_rdatatype_totext(rds.type, target));
            if (rds.type == dns_rdatatype_rrsig) {
                CHECK(str_totext(" ", target));
                CHECK(dns_rdatatype_totext(rds.covers, target));
                CHECK(str_totext(" ...\n", target));
            } else {
                dns_rdata_t rdata = DNS_RDATA_INIT;
                dns_rdataset_current(&rds, &rdata);
                CHECK(str_totext(" ", target));
                CHECK(dns_rdata_tofmttext(&rdata, dns_rootname,
                              0, 0, 0, " ", target));
                CHECK(str_totext("\n", target));
            }
        }
        dns_rdataset_disassociate(&rds);
        result = dns_rdataset_next(rdataset);
    } while (result == ISC_R_SUCCESS);

    if (result == ISC_R_NOMORE)
        result = ISC_R_SUCCESS;
 cleanup:
    if (dns_rdataset_isassociated(&rds))
        dns_rdataset_disassociate(&rds);

    return (result);
}

/*
 * Convert 'rdataset' to master file text format according to 'ctx',
 * storing the result in 'target'.  If 'owner_name' is NULL, it
 * is omitted; otherwise 'owner_name' must be valid and have at least
 * one label.
 */

static isc_result_t
rdataset_totext(dns_rdataset_t *rdataset,
        dns_name_t *owner_name,
        dns_totext_ctx_t *ctx,
        isc_boolean_t omit_final_dot,
        isc_buffer_t *target)
{
    isc_result_t result;
    unsigned int column;
    isc_boolean_t first = ISC_TRUE;
    isc_uint32_t current_ttl;
    isc_boolean_t current_ttl_valid;
    dns_rdatatype_t type;
    unsigned int type_start;
    dns_fixedname_t fixed;
    dns_name_t *name = NULL;

    REQUIRE(DNS_RDATASET_VALID(rdataset));

    rdataset->attributes |= DNS_RDATASETATTR_LOADORDER;
    result = dns_rdataset_first(rdataset);

    current_ttl = ctx->current_ttl;
    current_ttl_valid = ctx->current_ttl_valid;

    if (owner_name != NULL) {
        dns_fixedname_init(&fixed);
        name = dns_fixedname_name(&fixed);
        dns_name_copy(owner_name, name, NULL);
        dns_rdataset_getownercase(rdataset, name);
    }

    while (result == ISC_R_SUCCESS) {
        column = 0;

        /*
         * Indent?
         */
        if ((ctx->style.flags & DNS_STYLEFLAG_INDENT) != 0)
            RETERR(str_totext(dns_master_indentstr, target));

        /*
         * Comment?
         */
        if ((ctx->style.flags & DNS_STYLEFLAG_COMMENTDATA) != 0)
            RETERR(str_totext(";", target));

        /*
         * Owner name.
         */
        if (name != NULL &&
            ! ((ctx->style.flags & DNS_STYLEFLAG_OMIT_OWNER) != 0 &&
               !first))
        {
            unsigned int name_start = target->used;
            RETERR(dns_name_totext(name, omit_final_dot, target));
            column += target->used - name_start;
        }

        /*
         * TTL.
         */
        if ((ctx->style.flags & DNS_STYLEFLAG_NO_TTL) == 0 &&
            !((ctx->style.flags & DNS_STYLEFLAG_OMIT_TTL) != 0 &&
              current_ttl_valid &&
              rdataset->ttl == current_ttl))
        {
            char ttlbuf[64];
            isc_region_t r;
            unsigned int length;

            INDENT_TO(ttl_column);
            if ((ctx->style.flags & DNS_STYLEFLAG_TTL_UNITS) != 0) {
                length = target->used;
                result = dns_ttl_totext2(rdataset->ttl,
                            ISC_FALSE, ISC_FALSE,
                            target);
                if (result != ISC_R_SUCCESS)
                    return (result);
                column += target->used - length;
            } else {
                length = snprintf(ttlbuf, sizeof(ttlbuf), "%u",
                          rdataset->ttl);
                INSIST(length <= sizeof(ttlbuf));
                isc_buffer_availableregion(target, &r);
                if (r.length < length)
                    return (ISC_R_NOSPACE);
                memmove(r.base, ttlbuf, length);
                isc_buffer_add(target, length);
                column += length;
            }

            /*
             * If the $TTL directive is not in use, the TTL we
             * just printed becomes the default for subsequent RRs.
             */
            if ((ctx->style.flags & DNS_STYLEFLAG_TTL) == 0) {
                current_ttl = rdataset->ttl;
                current_ttl_valid = ISC_TRUE;
            }
        }

        /*
         * Class.
         */
        if ((ctx->style.flags & DNS_STYLEFLAG_NO_CLASS) == 0 &&
            ((ctx->style.flags & DNS_STYLEFLAG_OMIT_CLASS) == 0 ||
             ctx->class_printed == ISC_FALSE))
        {
            unsigned int class_start;
            INDENT_TO(class_column);
            class_start = target->used;
            if ((ctx->style.flags & DNS_STYLEFLAG_UNKNOWNFORMAT) != 0)
                result = dns_rdataclass_tounknowntext
                    (rdataset->rdclass, target);
            else
                result = dns_rdataclass_totext
                    (rdataset->rdclass, target);
            if (result != ISC_R_SUCCESS)
                return (result);
            column += (target->used - class_start);
        }

        /*
         * Type.
         */

        if ((rdataset->attributes & DNS_RDATASETATTR_NEGATIVE) != 0) {
            type = rdataset->covers;
        } else {
            type = rdataset->type;
        }

        INDENT_TO(type_column);
        type_start = target->used;
        if ((rdataset->attributes & DNS_RDATASETATTR_NEGATIVE) != 0)
            RETERR(str_totext("\\-", target));
        switch (type) {
        case dns_rdatatype_keydata:
#define KEYDATA "KEYDATA"
            if ((ctx->style.flags & DNS_STYLEFLAG_KEYDATA) != 0) {
                if (isc_buffer_availablelength(target) <
                    (sizeof(KEYDATA) - 1))
                    return (ISC_R_NOSPACE);
                isc_buffer_putstr(target, KEYDATA);
                break;
            }
            /* FALLTHROUGH */
        default:
            if ((ctx->style.flags & DNS_STYLEFLAG_UNKNOWNFORMAT) != 0)
                result = dns_rdatatype_tounknowntext(type, target);
            else
                result = dns_rdatatype_totext(type, target);
            if (result != ISC_R_SUCCESS)
                return (result);
        }
        column += (target->used - type_start);

        /*
         * Rdata.
         */
        INDENT_TO(rdata_column);
        if ((rdataset->attributes & DNS_RDATASETATTR_NEGATIVE) != 0) {
            if ((ctx->style.flags & DNS_STYLEFLAG_INDENT) != 0)
                RETERR(str_totext(dns_master_indentstr,
                          target));
            if (NXDOMAIN(rdataset))
                RETERR(str_totext(";-$NXDOMAIN\n", target));
            else
                RETERR(str_totext(";-$NXRRSET\n", target));
            /*
             * Print a summary of the cached records which make
             * up the negative response.
             */
            RETERR(ncache_summary(rdataset, omit_final_dot,
                          target));
            break;
        } else {
            dns_rdata_t rdata = DNS_RDATA_INIT;
            isc_region_t r;

            dns_rdataset_current(rdataset, &rdata);

            RETERR(dns_rdata_tofmttext(&rdata,
                           ctx->origin,
                           ctx->style.flags,
                           ctx->style.line_length -
                               ctx->style.rdata_column,
                           ctx->style.split_width,
                           ctx->linebreak,
                           target));

            isc_buffer_availableregion(target, &r);
            if (r.length < 1)
                return (ISC_R_NOSPACE);
            r.base[0] = '\n';
            isc_buffer_add(target, 1);
        }

        first = ISC_FALSE;
        result = dns_rdataset_next(rdataset);
    }

    if (result != ISC_R_NOMORE)
        return (result);

    /*
     * Update the ctx state to reflect what we just printed.
     * This is done last, only when we are sure we will return
     * success, because this function may be called multiple
     * times with increasing buffer sizes until it succeeds,
     * and failed attempts must not update the state prematurely.
     */
    ctx->class_printed = ISC_TRUE;
    ctx->current_ttl= current_ttl;
    ctx->current_ttl_valid = current_ttl_valid;

    return (ISC_R_SUCCESS);
}

/*
 * Print the name, type, and class of an empty rdataset,
 * such as those used to represent the question section
 * of a DNS message.
 */
static isc_result_t
question_totext(dns_rdataset_t *rdataset,
        dns_name_t *owner_name,
        dns_totext_ctx_t *ctx,
        isc_boolean_t omit_final_dot,
        isc_buffer_t *target)
{
    unsigned int column;
    isc_result_t result;
    isc_region_t r;

    REQUIRE(DNS_RDATASET_VALID(rdataset));
    result = dns_rdataset_first(rdataset);
    REQUIRE(result == ISC_R_NOMORE);

    column = 0;

    /* Owner name */
    {
        unsigned int name_start = target->used;
        RETERR(dns_name_totext(owner_name,
                       omit_final_dot,
                       target));
        column += target->used - name_start;
    }

    /* Class */
    {
        unsigned int class_start;
        INDENT_TO(class_column);
        class_start = target->used;
        if ((ctx->style.flags & DNS_STYLEFLAG_UNKNOWNFORMAT) != 0)
            result = dns_rdataclass_tounknowntext(rdataset->rdclass,
                                  target);
        else
            result = dns_rdataclass_totext(rdataset->rdclass,
                               target);
        if (result != ISC_R_SUCCESS)
            return (result);
        column += (target->used - class_start);
    }

    /* Type */
    {
        unsigned int type_start;
        INDENT_TO(type_column);
        type_start = target->used;
        if ((ctx->style.flags & DNS_STYLEFLAG_UNKNOWNFORMAT) != 0)
            result = dns_rdatatype_tounknowntext(rdataset->type,
                                 target);
        else
            result = dns_rdatatype_totext(rdataset->type,
                              target);
        if (result != ISC_R_SUCCESS)
            return (result);
        column += (target->used - type_start);
    }

    isc_buffer_availableregion(target, &r);
    if (r.length < 1)
        return (ISC_R_NOSPACE);
    r.base[0] = '\n';
    isc_buffer_add(target, 1);

    return (ISC_R_SUCCESS);
}

isc_result_t
dns_rdataset_totext(dns_rdataset_t *rdataset,
            dns_name_t *owner_name,
            isc_boolean_t omit_final_dot,
            isc_boolean_t question,
            isc_buffer_t *target)
{
    dns_totext_ctx_t ctx;
    isc_result_t result;
    result = totext_ctx_init(&dns_master_style_debug, &ctx);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "could not set master file style");
        return (ISC_R_UNEXPECTED);
    }

    /*
     * The caller might want to give us an empty owner
     * name (e.g. if they are outputting into a master
     * file and this rdataset has the same name as the
     * previous one.)
     */
    if (dns_name_countlabels(owner_name) == 0)
        owner_name = NULL;

    if (question)
        return (question_totext(rdataset, owner_name, &ctx,
                    omit_final_dot, target));
    else
        return (rdataset_totext(rdataset, owner_name, &ctx,
                    omit_final_dot, target));
}

isc_result_t
dns_master_rdatasettotext(dns_name_t *owner_name,
              dns_rdataset_t *rdataset,
              const dns_master_style_t *style,
              isc_buffer_t *target)
{
    dns_totext_ctx_t ctx;
    isc_result_t result;
    result = totext_ctx_init(style, &ctx);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "could not set master file style");
        return (ISC_R_UNEXPECTED);
    }

    return (rdataset_totext(rdataset, owner_name, &ctx,
                ISC_FALSE, target));
}

isc_result_t
dns_master_questiontotext(dns_name_t *owner_name,
              dns_rdataset_t *rdataset,
              const dns_master_style_t *style,
              isc_buffer_t *target)
{
    dns_totext_ctx_t ctx;
    isc_result_t result;
    result = totext_ctx_init(style, &ctx);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "could not set master file style");
        return (ISC_R_UNEXPECTED);
    }

    return (question_totext(rdataset, owner_name, &ctx,
                ISC_FALSE, target));
}

/*
 * Print an rdataset.  'buffer' is a scratch buffer, which must have been
 * dynamically allocated by the caller.  It must be large enough to
 * hold the result from dns_ttl_totext().  If more than that is needed,
 * the buffer will be grown automatically.
 */

static isc_result_t
dump_rdataset(isc_mem_t *mctx, dns_name_t *name, dns_rdataset_t *rdataset,
          dns_totext_ctx_t *ctx,
          isc_buffer_t *buffer, FILE *f)
{
    isc_region_t r;
    isc_result_t result;

    REQUIRE(buffer->length > 0);

    /*
     * Output a $TTL directive if needed.
     */

    if ((ctx->style.flags & DNS_STYLEFLAG_TTL) != 0) {
        if (ctx->current_ttl_valid == ISC_FALSE ||
            ctx->current_ttl != rdataset->ttl)
        {
            if ((ctx->style.flags & DNS_STYLEFLAG_COMMENT) != 0)
            {
                isc_buffer_clear(buffer);
                result = dns_ttl_totext(rdataset->ttl,
                            ISC_TRUE, buffer);
                INSIST(result == ISC_R_SUCCESS);
                isc_buffer_usedregion(buffer, &r);
                fprintf(f, "$TTL %u\t; %.*s\n", rdataset->ttl,
                    (int) r.length, (char *) r.base);
            } else {
                fprintf(f, "$TTL %u\n", rdataset->ttl);
            }
            ctx->current_ttl = rdataset->ttl;
            ctx->current_ttl_valid = ISC_TRUE;
        }
    }

    isc_buffer_clear(buffer);

    /*
     * Generate the text representation of the rdataset into
     * the buffer.  If the buffer is too small, grow it.
     */
    for (;;) {
        int newlength;
        void *newmem;
        result = rdataset_totext(rdataset, name, ctx,
                     ISC_FALSE, buffer);
        if (result != ISC_R_NOSPACE)
            break;

        newlength = buffer->length * 2;
        newmem = isc_mem_get(mctx, newlength);
        if (newmem == NULL)
            return (ISC_R_NOMEMORY);
        isc_mem_put(mctx, buffer->base, buffer->length);
        isc_buffer_init(buffer, newmem, newlength);
    }
    if (result != ISC_R_SUCCESS)
        return (result);

    /*
     * Write the buffer contents to the master file.
     */
    isc_buffer_usedregion(buffer, &r);
    result = isc_stdio_write(r.base, 1, (size_t)r.length, f, NULL);

    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "master file write failed: %s",
                 isc_result_totext(result));
        return (result);
    }

    return (ISC_R_SUCCESS);
}

/*
 * Define the order in which rdatasets should be printed in zone
 * files.  We will print SOA and NS records before others, SIGs
 * immediately following the things they sign, and order everything
 * else by RR number.  This is all just for aesthetics and
 * compatibility with buggy software that expects the SOA to be first;
 * the DNS specifications allow any order.
 */

static int
dump_order(const dns_rdataset_t *rds) {
    int t;
    int sig;
    if (rds->type == dns_rdatatype_rrsig) {
        t = rds->covers;
        sig = 1;
    } else {
        t = rds->type;
        sig = 0;
    }
    switch (t) {
    case dns_rdatatype_soa:
        t = 0;
        break;
    case dns_rdatatype_ns:
        t = 1;
        break;
    default:
        t += 2;
        break;
    }
    return (t << 1) + sig;
}

static int
dump_order_compare(const void *a, const void *b) {
    return (dump_order(*((const dns_rdataset_t * const *) a)) -
        dump_order(*((const dns_rdataset_t * const *) b)));
}

/*
 * Dump all the rdatasets of a domain name to a master file.  We make
 * a "best effort" attempt to sort the RRsets in a nice order, but if
 * there are more than MAXSORT RRsets, we punt and only sort them in
 * groups of MAXSORT.  This is not expected to ever happen in practice
 * since much less than 64 RR types have been registered with the
 * IANA, so far, and the output will be correct (though not
 * aesthetically pleasing) even if it does happen.
 */

#define MAXSORT 64

static isc_result_t
dump_rdatasets_text(isc_mem_t *mctx, dns_name_t *name,
            dns_rdatasetiter_t *rdsiter, dns_totext_ctx_t *ctx,
            isc_buffer_t *buffer, FILE *f)
{
    isc_result_t itresult, dumpresult;
    isc_region_t r;
    dns_rdataset_t rdatasets[MAXSORT];
    dns_rdataset_t *sorted[MAXSORT];
    int i, n;

    itresult = dns_rdatasetiter_first(rdsiter);
    dumpresult = ISC_R_SUCCESS;

    if (itresult == ISC_R_SUCCESS && ctx->neworigin != NULL) {
        isc_buffer_clear(buffer);
        itresult = dns_name_totext(ctx->neworigin, ISC_FALSE, buffer);
        RUNTIME_CHECK(itresult == ISC_R_SUCCESS);
        isc_buffer_usedregion(buffer, &r);
        fprintf(f, "$ORIGIN %.*s\n", (int) r.length, (char *) r.base);
        ctx->neworigin = NULL;
    }

 again:
    for (i = 0;
         itresult == ISC_R_SUCCESS && i < MAXSORT;
         itresult = dns_rdatasetiter_next(rdsiter), i++) {
        dns_rdataset_init(&rdatasets[i]);
        dns_rdatasetiter_current(rdsiter, &rdatasets[i]);
        sorted[i] = &rdatasets[i];
    }
    n = i;
    INSIST(n <= MAXSORT);

    qsort(sorted, n, sizeof(sorted[0]), dump_order_compare);

    for (i = 0; i < n; i++) {
        dns_rdataset_t *rds = sorted[i];
        if (ctx->style.flags & DNS_STYLEFLAG_TRUST)
            fprintf(f, "%s; %s\n",
                (ctx->style.flags & DNS_STYLEFLAG_INDENT)
                 ? dns_master_indentstr : "",
                dns_trust_totext(rds->trust));
        if (((rds->attributes & DNS_RDATASETATTR_NEGATIVE) != 0) &&
            (ctx->style.flags & DNS_STYLEFLAG_NCACHE) == 0) {
            /* Omit negative cache entries */
        } else {
            isc_result_t result =
                dump_rdataset(mctx, name, rds, ctx,
                           buffer, f);
            if (result != ISC_R_SUCCESS)
                dumpresult = result;
            if ((ctx->style.flags & DNS_STYLEFLAG_OMIT_OWNER) != 0)
                name = NULL;
        }
        if (ctx->style.flags & DNS_STYLEFLAG_RESIGN &&
            rds->attributes & DNS_RDATASETATTR_RESIGN) {
            isc_buffer_t b;
            char buf[sizeof("YYYYMMDDHHMMSS")];
            memset(buf, 0, sizeof(buf));
            isc_buffer_init(&b, buf, sizeof(buf) - 1);
            dns_time64_totext((isc_uint64_t)rds->resign, &b);
            fprintf(f, "%s; resign=%s\n",
                (ctx->style.flags & DNS_STYLEFLAG_INDENT)
                 ? dns_master_indentstr : "",
                buf);
        }
        dns_rdataset_disassociate(rds);
    }

    if (dumpresult != ISC_R_SUCCESS)
        return (dumpresult);

    /*
     * If we got more data than could be sorted at once,
     * go handle the rest.
     */
    if (itresult == ISC_R_SUCCESS)
        goto again;

    if (itresult == ISC_R_NOMORE)
        itresult = ISC_R_SUCCESS;

    return (itresult);
}

/*
 * Dump given RRsets in the "raw" format.
 */
static isc_result_t
dump_rdataset_raw(isc_mem_t *mctx, dns_name_t *name, dns_rdataset_t *rdataset,
          isc_buffer_t *buffer, FILE *f)
{
    isc_result_t result;
    isc_uint32_t totallen;
    isc_uint16_t dlen;
    isc_region_t r, r_hdr;

    REQUIRE(buffer->length > 0);
    REQUIRE(DNS_RDATASET_VALID(rdataset));

    rdataset->attributes |= DNS_RDATASETATTR_LOADORDER;
 restart:
    totallen = 0;
    result = dns_rdataset_first(rdataset);
    REQUIRE(result == ISC_R_SUCCESS);

    isc_buffer_clear(buffer);

    /*
     * Common header and owner name (length followed by name)
     * These fields should be in a moderate length, so we assume we
     * can store all of them in the initial buffer.
     */
    isc_buffer_availableregion(buffer, &r_hdr);
    INSIST(r_hdr.length >= sizeof(dns_masterrawrdataset_t));
    isc_buffer_putuint32(buffer, totallen); /* XXX: leave space */
    isc_buffer_putuint16(buffer, rdataset->rdclass); /* 16-bit class */
    isc_buffer_putuint16(buffer, rdataset->type); /* 16-bit type */
    isc_buffer_putuint16(buffer, rdataset->covers); /* same as type */
    isc_buffer_putuint32(buffer, rdataset->ttl); /* 32-bit TTL */
    isc_buffer_putuint32(buffer, dns_rdataset_count(rdataset));
    totallen = isc_buffer_usedlength(buffer);
    INSIST(totallen <= sizeof(dns_masterrawrdataset_t));

    dns_name_toregion(name, &r);
    INSIST(isc_buffer_availablelength(buffer) >=
           (sizeof(dlen) + r.length));
    dlen = (isc_uint16_t)r.length;
    isc_buffer_putuint16(buffer, dlen);
    isc_buffer_copyregion(buffer, &r);
    totallen += sizeof(dlen) + r.length;

    do {
        dns_rdata_t rdata = DNS_RDATA_INIT;

        dns_rdataset_current(rdataset, &rdata);
        dns_rdata_toregion(&rdata, &r);
        INSIST(r.length <= 0xffffU);
        dlen = (isc_uint16_t)r.length;

        /*
         * Copy the rdata into the buffer.  If the buffer is too small,
         * grow it.  This should be rare, so we'll simply restart the
         * entire procedure (or should we copy the old data and
         * continue?).
         */
        if (isc_buffer_availablelength(buffer) <
                         sizeof(dlen) + r.length) {
            int newlength;
            void *newmem;

            newlength = buffer->length * 2;
            newmem = isc_mem_get(mctx, newlength);
            if (newmem == NULL)
                return (ISC_R_NOMEMORY);
            isc_mem_put(mctx, buffer->base, buffer->length);
            isc_buffer_init(buffer, newmem, newlength);
            goto restart;
        }
        isc_buffer_putuint16(buffer, dlen);
        isc_buffer_copyregion(buffer, &r);
        totallen += sizeof(dlen) + r.length;

        result = dns_rdataset_next(rdataset);
    } while (result == ISC_R_SUCCESS);

    if (result != ISC_R_NOMORE)
        return (result);

    /*
     * Fill in the total length field.
     * XXX: this is a bit tricky.  Since we have already "used" the space
     * for the total length in the buffer, we first remember the entire
     * buffer length in the region, "rewind", and then write the value.
     */
    isc_buffer_usedregion(buffer, &r);
    isc_buffer_clear(buffer);
    isc_buffer_putuint32(buffer, totallen);
    INSIST(isc_buffer_usedlength(buffer) < totallen);

    /*
     * Write the buffer contents to the raw master file.
     */
    result = isc_stdio_write(r.base, 1, (size_t)r.length, f, NULL);

    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "raw master file write failed: %s",
                 isc_result_totext(result));
        return (result);
    }

    return (result);
}

static isc_result_t
dump_rdatasets_raw(isc_mem_t *mctx, dns_name_t *name,
           dns_rdatasetiter_t *rdsiter, dns_totext_ctx_t *ctx,
           isc_buffer_t *buffer, FILE *f)
{
    isc_result_t result;
    dns_rdataset_t rdataset;

    for (result = dns_rdatasetiter_first(rdsiter);
         result == ISC_R_SUCCESS;
         result = dns_rdatasetiter_next(rdsiter)) {

        dns_rdataset_init(&rdataset);
        dns_rdatasetiter_current(rdsiter, &rdataset);

        if (((rdataset.attributes & DNS_RDATASETATTR_NEGATIVE) != 0) &&
            (ctx->style.flags & DNS_STYLEFLAG_NCACHE) == 0) {
            /* Omit negative cache entries */
        } else {
            result = dump_rdataset_raw(mctx, name, &rdataset,
                           buffer, f);
        }
        dns_rdataset_disassociate(&rdataset);
        if (result != ISC_R_SUCCESS)
            return (result);
    }

    if (result == ISC_R_NOMORE)
        result = ISC_R_SUCCESS;

    return (result);
}

static isc_result_t
dump_rdatasets_map(isc_mem_t *mctx, dns_name_t *name,
           dns_rdatasetiter_t *rdsiter, dns_totext_ctx_t *ctx,
           isc_buffer_t *buffer, FILE *f)
{
    UNUSED(mctx);
    UNUSED(name);
    UNUSED(rdsiter);
    UNUSED(ctx);
    UNUSED(buffer);
    UNUSED(f);

    return (ISC_R_NOTIMPLEMENTED);
}

/*
 * Initial size of text conversion buffer.  The buffer is used
 * for several purposes: converting origin names, rdatasets,
 * $DATE timestamps, and comment strings for $TTL directives.
 *
 * When converting rdatasets, it is dynamically resized, but
 * when converting origins, timestamps, etc it is not.  Therefore,
 * the initial size must large enough to hold the longest possible
 * text representation of any domain name (for $ORIGIN).
 */
static const int initial_buffer_length = 1200;

static isc_result_t
dumptostreaminc(dns_dumpctx_t *dctx);

static void
dumpctx_destroy(dns_dumpctx_t *dctx) {

    dctx->magic = 0;
    DESTROYLOCK(&dctx->lock);
    dns_dbiterator_destroy(&dctx->dbiter);
    if (dctx->version != NULL)
        dns_db_closeversion(dctx->db, &dctx->version, ISC_FALSE);
    dns_db_detach(&dctx->db);
    if (dctx->task != NULL)
        isc_task_detach(&dctx->task);
    if (dctx->file != NULL)
        isc_mem_free(dctx->mctx, dctx->file);
    if (dctx->tmpfile != NULL)
        isc_mem_free(dctx->mctx, dctx->tmpfile);
    isc_mem_putanddetach(&dctx->mctx, dctx, sizeof(*dctx));
}

void
dns_dumpctx_attach(dns_dumpctx_t *source, dns_dumpctx_t **target) {

    REQUIRE(DNS_DCTX_VALID(source));
    REQUIRE(target != NULL && *target == NULL);

    LOCK(&source->lock);
    INSIST(source->references > 0);
    source->references++;
    INSIST(source->references != 0);    /* Overflow? */
    UNLOCK(&source->lock);

    *target = source;
}

void
dns_dumpctx_detach(dns_dumpctx_t **dctxp) {
    dns_dumpctx_t *dctx;
    isc_boolean_t need_destroy = ISC_FALSE;

    REQUIRE(dctxp != NULL);
    dctx = *dctxp;
    REQUIRE(DNS_DCTX_VALID(dctx));

    *dctxp = NULL;

    LOCK(&dctx->lock);
    INSIST(dctx->references != 0);
    dctx->references--;
    if (dctx->references == 0)
        need_destroy = ISC_TRUE;
    UNLOCK(&dctx->lock);
    if (need_destroy)
        dumpctx_destroy(dctx);
}

dns_dbversion_t *
dns_dumpctx_version(dns_dumpctx_t *dctx) {
    REQUIRE(DNS_DCTX_VALID(dctx));
    return (dctx->version);
}

dns_db_t *
dns_dumpctx_db(dns_dumpctx_t *dctx) {
    REQUIRE(DNS_DCTX_VALID(dctx));
    return (dctx->db);
}

void
dns_dumpctx_cancel(dns_dumpctx_t *dctx) {
    REQUIRE(DNS_DCTX_VALID(dctx));

    LOCK(&dctx->lock);
    dctx->canceled = ISC_TRUE;
    UNLOCK(&dctx->lock);
}

static isc_result_t
flushandsync(FILE *f, isc_result_t result, const char *temp) {
    isc_boolean_t logit = ISC_TF(result == ISC_R_SUCCESS);

    if (result == ISC_R_SUCCESS)
        result = isc_stdio_flush(f);
    if (result != ISC_R_SUCCESS && logit) {
        if (temp != NULL)
            isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                      DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                      "dumping to master file: %s: flush: %s",
                      temp, isc_result_totext(result));
        else
            isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                      DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                      "dumping to stream: flush: %s",
                      isc_result_totext(result));
        logit = ISC_FALSE;
    }

    if (result == ISC_R_SUCCESS)
        result = isc_stdio_sync(f);
    if (result != ISC_R_SUCCESS && logit) {
        if (temp != NULL)
            isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                      DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                      "dumping to master file: %s: fsync: %s",
                      temp, isc_result_totext(result));
        else
            isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                      DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                      "dumping to stream: fsync: %s",
                      isc_result_totext(result));
    }
    return (result);
}

static isc_result_t
closeandrename(FILE *f, isc_result_t result, const char *temp, const char *file)
{
    isc_result_t tresult;
    isc_boolean_t logit = ISC_TF(result == ISC_R_SUCCESS);

    result = flushandsync(f, result, temp);
    if (result != ISC_R_SUCCESS)
        logit = ISC_FALSE;

    tresult = isc_stdio_close(f);
    if (result == ISC_R_SUCCESS)
        result = tresult;
    if (result != ISC_R_SUCCESS && logit) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping master file: %s: fclose: %s",
                  temp, isc_result_totext(result));
        logit = ISC_FALSE;
    }
    if (result == ISC_R_SUCCESS)
        result = isc_file_rename(temp, file);
    else
        (void)isc_file_remove(temp);
    if (result != ISC_R_SUCCESS && logit) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping master file: rename: %s: %s",
                  file, isc_result_totext(result));
    }
    return (result);
}

static void
dump_quantum(isc_task_t *task, isc_event_t *event) {
    isc_result_t result;
    isc_result_t tresult;
    dns_dumpctx_t *dctx;

    REQUIRE(event != NULL);
    dctx = event->ev_arg;
    REQUIRE(DNS_DCTX_VALID(dctx));
    if (dctx->canceled)
        result = ISC_R_CANCELED;
    else
        result = dumptostreaminc(dctx);
    if (result == DNS_R_CONTINUE) {
        event->ev_arg = dctx;
        isc_task_send(task, &event);
        return;
    }

    if (dctx->file != NULL) {
        tresult = closeandrename(dctx->f, result,
                     dctx->tmpfile, dctx->file);
        if (tresult != ISC_R_SUCCESS && result == ISC_R_SUCCESS)
            result = tresult;
    } else
        result = flushandsync(dctx->f, result, NULL);
    (dctx->done)(dctx->done_arg, result);
    isc_event_free(&event);
    dns_dumpctx_detach(&dctx);
}

static isc_result_t
task_send(dns_dumpctx_t *dctx) {
    isc_event_t *event;

    event = isc_event_allocate(dctx->mctx, NULL, DNS_EVENT_DUMPQUANTUM,
                   dump_quantum, dctx, sizeof(*event));
    if (event == NULL)
        return (ISC_R_NOMEMORY);
    isc_task_send(dctx->task, &event);
    return (ISC_R_SUCCESS);
}

static isc_result_t
dumpctx_create(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
           const dns_master_style_t *style, FILE *f, dns_dumpctx_t **dctxp,
           dns_masterformat_t format, dns_masterrawheader_t *header)
{
    dns_dumpctx_t *dctx;
    isc_result_t result;
    unsigned int options;

    dctx = isc_mem_get(mctx, sizeof(*dctx));
    if (dctx == NULL)
        return (ISC_R_NOMEMORY);

    dctx->mctx = NULL;
    dctx->f = f;
    dctx->dbiter = NULL;
    dctx->db = NULL;
    dctx->version = NULL;
    dctx->done = NULL;
    dctx->done_arg = NULL;
    dctx->task = NULL;
    dctx->nodes = 0;
    dctx->first = ISC_TRUE;
    dctx->canceled = ISC_FALSE;
    dctx->file = NULL;
    dctx->tmpfile = NULL;
    dctx->format = format;
    if (header == NULL)
        dns_master_initrawheader(&dctx->header);
    else
        dctx->header = *header;

    switch (format) {
    case dns_masterformat_text:
        dctx->dumpsets = dump_rdatasets_text;
        break;
    case dns_masterformat_raw:
        dctx->dumpsets = dump_rdatasets_raw;
        break;
    case dns_masterformat_map:
        dctx->dumpsets = dump_rdatasets_map;
        break;
    default:
        INSIST(0);
        break;
    }

    result = totext_ctx_init(style, &dctx->tctx);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "could not set master file style");
        goto cleanup;
    }

    isc_stdtime_get(&dctx->now);
    dns_db_attach(db, &dctx->db);

    dctx->do_date = dns_db_iscache(dctx->db);

    if (dctx->format == dns_masterformat_text &&
        (dctx->tctx.style.flags & DNS_STYLEFLAG_REL_OWNER) != 0) {
        options = DNS_DB_RELATIVENAMES;
    } else
        options = 0;
    result = dns_db_createiterator(dctx->db, options, &dctx->dbiter);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

    result = isc_mutex_init(&dctx->lock);
    if (result != ISC_R_SUCCESS)
        goto cleanup;
    if (version != NULL)
        dns_db_attachversion(dctx->db, version, &dctx->version);
    else if (!dns_db_iscache(db))
        dns_db_currentversion(dctx->db, &dctx->version);
    isc_mem_attach(mctx, &dctx->mctx);
    dctx->references = 1;
    dctx->magic = DNS_DCTX_MAGIC;
    *dctxp = dctx;
    return (ISC_R_SUCCESS);

 cleanup:
    if (dctx->dbiter != NULL)
        dns_dbiterator_destroy(&dctx->dbiter);
    if (dctx->db != NULL)
        dns_db_detach(&dctx->db);
    if (dctx != NULL)
        isc_mem_put(mctx, dctx, sizeof(*dctx));
    return (result);
}

static isc_result_t
writeheader(dns_dumpctx_t *dctx) {
    isc_result_t result = ISC_R_SUCCESS;
    isc_buffer_t buffer;
    char *bufmem;
    isc_region_t r;
    dns_masterrawheader_t rawheader;
    isc_uint32_t rawversion, now32;

    bufmem = isc_mem_get(dctx->mctx, initial_buffer_length);
    if (bufmem == NULL)
        return (ISC_R_NOMEMORY);

    isc_buffer_init(&buffer, bufmem, initial_buffer_length);

    switch (dctx->format) {
    case dns_masterformat_text:
        /*
         * If the database has cache semantics, output an
         * RFC2540 $DATE directive so that the TTLs can be
         * adjusted when it is reloaded.  For zones it is not
         * really needed, and it would make the file
         * incompatible with pre-RFC2540 software, so we omit
         * it in the zone case.
         */
        if (dctx->do_date) {
            result = dns_time32_totext(dctx->now, &buffer);
            RUNTIME_CHECK(result == ISC_R_SUCCESS);
            isc_buffer_usedregion(&buffer, &r);
            fprintf(dctx->f, "$DATE %.*s\n",
                (int) r.length, (char *) r.base);
        }
        break;
    case dns_masterformat_raw:
    case dns_masterformat_map:
        r.base = (unsigned char *)&rawheader;
        r.length = sizeof(rawheader);
        isc_buffer_region(&buffer, &r);
#if !defined(STDTIME_ON_32BITS) || (STDTIME_ON_32BITS + 0) != 1
        /*
         * We assume isc_stdtime_t is a 32-bit integer,
         * which should be the case on most platforms.
         * If it turns out to be uncommon, we'll need
         * to bump the version number and revise the
         * header format.
         */
        isc_log_write(dns_lctx,
                  ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP,
                  ISC_LOG_INFO,
                  "dumping master file in raw "
                  "format: stdtime is not 32bits");
        now32 = 0;
#else
        now32 = dctx->now;
#endif
        rawversion = 1;
        if ((dctx->header.flags & DNS_MASTERRAW_COMPAT) != 0)
            rawversion = 0;

        isc_buffer_putuint32(&buffer, dctx->format);
        isc_buffer_putuint32(&buffer, rawversion);
        isc_buffer_putuint32(&buffer, now32);

        if (rawversion == 1) {
            isc_buffer_putuint32(&buffer, dctx->header.flags);
            isc_buffer_putuint32(&buffer,
                         dctx->header.sourceserial);
            isc_buffer_putuint32(&buffer, dctx->header.lastxfrin);
        }

        INSIST(isc_buffer_usedlength(&buffer) <= sizeof(rawheader));
        result = isc_stdio_write(buffer.base, 1,
                     isc_buffer_usedlength(&buffer),
                     dctx->f, NULL);
        if (result != ISC_R_SUCCESS)
            break;

        break;
    default:
        INSIST(0);
    }

    isc_mem_put(dctx->mctx, buffer.base, buffer.length);
    return (result);
}

static isc_result_t
dumptostreaminc(dns_dumpctx_t *dctx) {
    isc_result_t result = ISC_R_SUCCESS;
    isc_buffer_t buffer;
    char *bufmem;
    dns_name_t *name;
    dns_fixedname_t fixname;
    unsigned int nodes;
    isc_time_t start;

    bufmem = isc_mem_get(dctx->mctx, initial_buffer_length);
    if (bufmem == NULL)
        return (ISC_R_NOMEMORY);

    isc_buffer_init(&buffer, bufmem, initial_buffer_length);

    dns_fixedname_init(&fixname);
    name = dns_fixedname_name(&fixname);

    if (dctx->first) {
        CHECK(writeheader(dctx));

        /*
         * Fast format is not currently written incrementally,
         * so we make the call to dns_db_serialize() here.
         * If the database is anything other than an rbtdb,
         * this should result in not implemented
         */
        if (dctx->format == dns_masterformat_map) {
            result = dns_db_serialize(dctx->db, dctx->version,
                          dctx->f);
            goto cleanup;
        }

        result = dns_dbiterator_first(dctx->dbiter);
        if (result != ISC_R_SUCCESS && result != ISC_R_NOMORE)
            goto cleanup;

        dctx->first = ISC_FALSE;
    } else
        result = ISC_R_SUCCESS;

    nodes = dctx->nodes;
    isc_time_now(&start);
    while (result == ISC_R_SUCCESS && (dctx->nodes == 0 || nodes--)) {
        dns_rdatasetiter_t *rdsiter = NULL;
        dns_dbnode_t *node = NULL;

        result = dns_dbiterator_current(dctx->dbiter, &node, name);
        if (result != ISC_R_SUCCESS && result != DNS_R_NEWORIGIN)
            break;
        if (result == DNS_R_NEWORIGIN) {
            dns_name_t *origin =
                dns_fixedname_name(&dctx->tctx.origin_fixname);
            result = dns_dbiterator_origin(dctx->dbiter, origin);
            RUNTIME_CHECK(result == ISC_R_SUCCESS);
            if ((dctx->tctx.style.flags &
                 DNS_STYLEFLAG_REL_DATA) != 0)
                dctx->tctx.origin = origin;
            dctx->tctx.neworigin = origin;
        }
        result = dns_db_allrdatasets(dctx->db, node, dctx->version,
                         dctx->now, &rdsiter);
        if (result != ISC_R_SUCCESS) {
            dns_db_detachnode(dctx->db, &node);
            goto cleanup;
        }
        result = (dctx->dumpsets)(dctx->mctx, name, rdsiter,
                      &dctx->tctx, &buffer, dctx->f);
        dns_rdatasetiter_destroy(&rdsiter);
        if (result != ISC_R_SUCCESS) {
            dns_db_detachnode(dctx->db, &node);
            goto cleanup;
        }
        dns_db_detachnode(dctx->db, &node);
        result = dns_dbiterator_next(dctx->dbiter);
    }

    /*
     * Work out how many nodes can be written in the time between
     * two requests to the nameserver.  Smooth the resulting number and
     * use it as a estimate for the number of nodes to be written in the
     * next iteration.
     */
    if (dctx->nodes != 0 && result == ISC_R_SUCCESS) {
        unsigned int pps = dns_pps; /* packets per second */
        unsigned int interval;
        isc_uint64_t usecs;
        isc_time_t end;

        isc_time_now(&end);
        if (pps < 100)
            pps = 100;
        interval = 1000000 / pps;   /* interval in usecs */
        if (interval == 0)
            interval = 1;
        usecs = isc_time_microdiff(&end, &start);
        if (usecs == 0) {
            dctx->nodes = dctx->nodes * 2;
            if (dctx->nodes > 1000)
                dctx->nodes = 1000;
        } else {
            nodes = dctx->nodes * interval;
            nodes /= (unsigned int)usecs;
            if (nodes == 0)
                nodes = 1;
            else if (nodes > 1000)
                nodes = 1000;

            /* Smooth and assign. */
            dctx->nodes = (nodes + dctx->nodes * 7) / 8;

            isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                      DNS_LOGMODULE_MASTERDUMP,
                      ISC_LOG_DEBUG(1),
                      "dumptostreaminc(%p) new nodes -> %d\n",
                      dctx, dctx->nodes);
        }
        result = DNS_R_CONTINUE;
    } else if (result == ISC_R_NOMORE)
        result = ISC_R_SUCCESS;
 cleanup:
    RUNTIME_CHECK(dns_dbiterator_pause(dctx->dbiter) == ISC_R_SUCCESS);
    isc_mem_put(dctx->mctx, buffer.base, buffer.length);
    return (result);
}

isc_result_t
dns_master_dumptostreaminc(isc_mem_t *mctx, dns_db_t *db,
               dns_dbversion_t *version,
               const dns_master_style_t *style,
               FILE *f, isc_task_t *task,
               dns_dumpdonefunc_t done, void *done_arg,
               dns_dumpctx_t **dctxp)
{
    dns_dumpctx_t *dctx = NULL;
    isc_result_t result;

    REQUIRE(task != NULL);
    REQUIRE(f != NULL);
    REQUIRE(done != NULL);

    result = dumpctx_create(mctx, db, version, style, f, &dctx,
                dns_masterformat_text, NULL);
    if (result != ISC_R_SUCCESS)
        return (result);
    isc_task_attach(task, &dctx->task);
    dctx->done = done;
    dctx->done_arg = done_arg;
    dctx->nodes = 100;

    result = task_send(dctx);
    if (result == ISC_R_SUCCESS) {
        dns_dumpctx_attach(dctx, dctxp);
        return (DNS_R_CONTINUE);
    }

    dns_dumpctx_detach(&dctx);
    return (result);
}

/*
 * Dump an entire database into a master file.
 */
isc_result_t
dns_master_dumptostream(isc_mem_t *mctx, dns_db_t *db,
            dns_dbversion_t *version,
            const dns_master_style_t *style,
            FILE *f)
{
    return (dns_master_dumptostream3(mctx, db, version, style,
                     dns_masterformat_text, NULL, f));
}

isc_result_t
dns_master_dumptostream2(isc_mem_t *mctx, dns_db_t *db,
             dns_dbversion_t *version,
             const dns_master_style_t *style,
             dns_masterformat_t format, FILE *f)
{
    return (dns_master_dumptostream3(mctx, db, version, style,
                     format, NULL, f));
}

isc_result_t
dns_master_dumptostream3(isc_mem_t *mctx, dns_db_t *db,
             dns_dbversion_t *version,
             const dns_master_style_t *style,
             dns_masterformat_t format,
             dns_masterrawheader_t *header, FILE *f)
{
    dns_dumpctx_t *dctx = NULL;
    isc_result_t result;

    result = dumpctx_create(mctx, db, version, style, f, &dctx,
                format, header);
    if (result != ISC_R_SUCCESS)
        return (result);

    result = dumptostreaminc(dctx);
    INSIST(result != DNS_R_CONTINUE);
    dns_dumpctx_detach(&dctx);

    result = flushandsync(f, result, NULL);
    return (result);
}

static isc_result_t
opentmp(isc_mem_t *mctx, dns_masterformat_t format, const char *file,
    char **tempp, FILE **fp) {
    FILE *f = NULL;
    isc_result_t result;
    char *tempname = NULL;
    int tempnamelen;

    tempnamelen = strlen(file) + 20;
    tempname = isc_mem_allocate(mctx, tempnamelen);
    if (tempname == NULL)
        return (ISC_R_NOMEMORY);

    result = isc_file_mktemplate(file, tempname, tempnamelen);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

    if (format == dns_masterformat_text)
        result = isc_file_openunique(tempname, &f);
    else
        result = isc_file_bopenunique(tempname, &f);
    if (result != ISC_R_SUCCESS) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping master file: %s: open: %s",
                  tempname, isc_result_totext(result));
        goto cleanup;
    }
    *tempp = tempname;
    *fp = f;
    return (ISC_R_SUCCESS);

cleanup:
    isc_mem_free(mctx, tempname);
    return (result);
}

isc_result_t
dns_master_dumpinc(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
           const dns_master_style_t *style, const char *filename,
           isc_task_t *task, dns_dumpdonefunc_t done, void *done_arg,
           dns_dumpctx_t **dctxp)
{
    return (dns_master_dumpinc3(mctx, db, version, style, filename, task,
                    done, done_arg, dctxp,
                    dns_masterformat_text, NULL));
}

isc_result_t
dns_master_dumpinc2(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
            const dns_master_style_t *style, const char *filename,
            isc_task_t *task, dns_dumpdonefunc_t done, void *done_arg,
            dns_dumpctx_t **dctxp, dns_masterformat_t format)
{
    return (dns_master_dumpinc3(mctx, db, version, style, filename, task,
                    done, done_arg, dctxp, format, NULL));
}

isc_result_t
dns_master_dumpinc3(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
            const dns_master_style_t *style, const char *filename,
            isc_task_t *task, dns_dumpdonefunc_t done, void *done_arg,
            dns_dumpctx_t **dctxp, dns_masterformat_t format,
            dns_masterrawheader_t *header)
{
    FILE *f = NULL;
    isc_result_t result;
    char *tempname = NULL;
    char *file = NULL;
    dns_dumpctx_t *dctx = NULL;

    file = isc_mem_strdup(mctx, filename);
    if (file == NULL)
        return (ISC_R_NOMEMORY);

    result = opentmp(mctx, format, filename, &tempname, &f);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

    result = dumpctx_create(mctx, db, version, style, f, &dctx,
                format, header);
    if (result != ISC_R_SUCCESS) {
        (void)isc_stdio_close(f);
        (void)isc_file_remove(tempname);
        goto cleanup;
    }

    isc_task_attach(task, &dctx->task);
    dctx->done = done;
    dctx->done_arg = done_arg;
    dctx->nodes = 100;
    dctx->file = file;
    file = NULL;
    dctx->tmpfile = tempname;
    tempname = NULL;

    result = task_send(dctx);
    if (result == ISC_R_SUCCESS) {
        dns_dumpctx_attach(dctx, dctxp);
        return (DNS_R_CONTINUE);
    }

 cleanup:
    if (dctx != NULL)
        dns_dumpctx_detach(&dctx);
    if (file != NULL)
        isc_mem_free(mctx, file);
    if (tempname != NULL)
        isc_mem_free(mctx, tempname);
    return (result);
}

isc_result_t
dns_master_dump(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
        const dns_master_style_t *style, const char *filename)
{
    return (dns_master_dump3(mctx, db, version, style, filename,
                 dns_masterformat_text, NULL));
}

isc_result_t
dns_master_dump2(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
         const dns_master_style_t *style, const char *filename,
         dns_masterformat_t format)
{
    return (dns_master_dump3(mctx, db, version, style, filename,
                 format, NULL));
}

isc_result_t
dns_master_dump3(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
         const dns_master_style_t *style, const char *filename,
         dns_masterformat_t format, dns_masterrawheader_t *header)
{
    FILE *f = NULL;
    isc_result_t result;
    char *tempname;
    dns_dumpctx_t *dctx = NULL;

    result = opentmp(mctx, format, filename, &tempname, &f);
    if (result != ISC_R_SUCCESS)
        return (result);

    result = dumpctx_create(mctx, db, version, style, f, &dctx,
                format, header);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

    result = dumptostreaminc(dctx);
    INSIST(result != DNS_R_CONTINUE);
    dns_dumpctx_detach(&dctx);

    result = closeandrename(f, result, tempname, filename);

 cleanup:
    isc_mem_free(mctx, tempname);
    return (result);
}

/*
 * Dump a database node into a master file.
 * XXX: this function assumes the text format.
 */
isc_result_t
dns_master_dumpnodetostream(isc_mem_t *mctx, dns_db_t *db,
                dns_dbversion_t *version,
                dns_dbnode_t *node, dns_name_t *name,
                const dns_master_style_t *style,
                FILE *f)
{
    isc_result_t result;
    isc_buffer_t buffer;
    char *bufmem;
    isc_stdtime_t now;
    dns_totext_ctx_t ctx;
    dns_rdatasetiter_t *rdsiter = NULL;

    result = totext_ctx_init(style, &ctx);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "could not set master file style");
        return (ISC_R_UNEXPECTED);
    }

    isc_stdtime_get(&now);

    bufmem = isc_mem_get(mctx, initial_buffer_length);
    if (bufmem == NULL)
        return (ISC_R_NOMEMORY);

    isc_buffer_init(&buffer, bufmem, initial_buffer_length);

    result = dns_db_allrdatasets(db, node, version, now, &rdsiter);
    if (result != ISC_R_SUCCESS)
        goto failure;
    result = dump_rdatasets_text(mctx, name, rdsiter, &ctx, &buffer, f);
    if (result != ISC_R_SUCCESS)
        goto failure;
    dns_rdatasetiter_destroy(&rdsiter);

    result = ISC_R_SUCCESS;

 failure:
    isc_mem_put(mctx, buffer.base, buffer.length);
    return (result);
}

isc_result_t
dns_master_dumpnode(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
            dns_dbnode_t *node, dns_name_t *name,
            const dns_master_style_t *style, const char *filename)
{
    FILE *f = NULL;
    isc_result_t result;

    result = isc_stdio_open(filename, "w", &f);
    if (result != ISC_R_SUCCESS) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping node to file: %s: open: %s", filename,
                  isc_result_totext(result));
        return (ISC_R_UNEXPECTED);
    }

    result = dns_master_dumpnodetostream(mctx, db, version, node, name,
                         style, f);
    if (result != ISC_R_SUCCESS) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping master file: %s: dump: %s", filename,
                  isc_result_totext(result));
        (void)isc_stdio_close(f);
        return (ISC_R_UNEXPECTED);
    }

    result = isc_stdio_close(f);
    if (result != ISC_R_SUCCESS) {
        isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
                  DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
                  "dumping master file: %s: close: %s", filename,
                  isc_result_totext(result));
        return (ISC_R_UNEXPECTED);
    }

    return (result);
}

unsigned int
dns_master_styleflags(const dns_master_style_t *style) {
    REQUIRE(style != NULL);
    return (style->flags);
}

isc_result_t
dns_master_stylecreate(dns_master_style_t **stylep, unsigned int flags,
               unsigned int ttl_column, unsigned int class_column,
               unsigned int type_column, unsigned int rdata_column,
               unsigned int line_length, unsigned int tab_width,
               isc_mem_t *mctx)
{
    return (dns_master_stylecreate2(stylep, flags, ttl_column,
                    class_column, type_column,
                    rdata_column, line_length,
                    tab_width, 0xffffffff, mctx));
}

isc_result_t
dns_master_stylecreate2(dns_master_style_t **stylep, unsigned int flags,
            unsigned int ttl_column, unsigned int class_column,
            unsigned int type_column, unsigned int rdata_column,
            unsigned int line_length, unsigned int tab_width,
            unsigned int split_width, isc_mem_t *mctx)
{
    dns_master_style_t *style;

    REQUIRE(stylep != NULL && *stylep == NULL);
    style = isc_mem_get(mctx, sizeof(*style));
    if (style == NULL)
        return (ISC_R_NOMEMORY);

    style->flags = flags;
    style->ttl_column = ttl_column;
    style->class_column = class_column;
    style->type_column = type_column;
    style->rdata_column = rdata_column;
    style->line_length = line_length;
    style->tab_width = tab_width;
    style->split_width = split_width;

    *stylep = style;
    return (ISC_R_SUCCESS);
}

void
dns_master_styledestroy(dns_master_style_t **stylep, isc_mem_t *mctx) {
    dns_master_style_t *style;

    REQUIRE(stylep != NULL && *stylep != NULL);
    style = *stylep;
    *stylep = NULL;
    isc_mem_put(mctx, style, sizeof(*style));
}