OpenZFS 7247 - zfs receive of deduplicated stream fails

[mirror_zfs.git] / lib / libzfs / libzfs_sendrecv.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
 * Copyright (c) 2012, Joyent, Inc. All rights reserved.
 * Copyright (c) 2012 Pawel Jakub Dawidek <pawel@dawidek.net>.
 * All rights reserved
 * Copyright (c) 2013 Steven Hartland. All rights reserved.
 * Copyright 2015, OmniTI Computer Consulting, Inc. All rights reserved.
 */

#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <libintl.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <stddef.h>
#include <fcntl.h>
#include <sys/mount.h>
#include <sys/mntent.h>
#include <sys/mnttab.h>
#include <sys/avl.h>
#include <sys/debug.h>
#include <sys/stat.h>
#include <stddef.h>
#include <pthread.h>
#include <umem.h>
#include <time.h>

#include <libzfs.h>
#include <libzfs_core.h>

#include "zfs_namecheck.h"
#include "zfs_prop.h"
#include "zfs_fletcher.h"
#include "libzfs_impl.h"
#include <zlib.h>
#include <sys/zio_checksum.h>
#include <sys/ddt.h>
#include <sys/socket.h>
#include <sys/sha2.h>

/* in libzfs_dataset.c */
extern void zfs_setprop_error(libzfs_handle_t *, zfs_prop_t, int, char *);

static int zfs_receive_impl(libzfs_handle_t *, const char *, const char *,
    recvflags_t *, int, const char *, nvlist_t *, avl_tree_t *, char **, int,
    uint64_t *, const char *);
static int guid_to_name(libzfs_handle_t *, const char *,
    uint64_t, boolean_t, char *);

static const zio_cksum_t zero_cksum = { { 0 } };

typedef struct dedup_arg {
        int     inputfd;
        int     outputfd;
        libzfs_handle_t  *dedup_hdl;
} dedup_arg_t;

typedef struct progress_arg {
        zfs_handle_t *pa_zhp;
        int pa_fd;
        boolean_t pa_parsable;
} progress_arg_t;

typedef struct dataref {
        uint64_t ref_guid;
        uint64_t ref_object;
        uint64_t ref_offset;
} dataref_t;

typedef struct dedup_entry {
        struct dedup_entry      *dde_next;
        zio_cksum_t dde_chksum;
        uint64_t dde_prop;
        dataref_t dde_ref;
} dedup_entry_t;

#define MAX_DDT_PHYSMEM_PERCENT         20
#define SMALLEST_POSSIBLE_MAX_DDT_MB            128

typedef struct dedup_table {
        dedup_entry_t   **dedup_hash_array;
        umem_cache_t    *ddecache;
        uint64_t        max_ddt_size;  /* max dedup table size in bytes */
        uint64_t        cur_ddt_size;  /* current dedup table size in bytes */
        uint64_t        ddt_count;
        int             numhashbits;
        boolean_t       ddt_full;
} dedup_table_t;

static int
high_order_bit(uint64_t n)
{
        int count;

        for (count = 0; n != 0; count++)
                n >>= 1;
        return (count);
}

static size_t
ssread(void *buf, size_t len, FILE *stream)
{
        size_t outlen;

        if ((outlen = fread(buf, len, 1, stream)) == 0)
                return (0);

        return (outlen);
}

static void
ddt_hash_append(libzfs_handle_t *hdl, dedup_table_t *ddt, dedup_entry_t **ddepp,
    zio_cksum_t *cs, uint64_t prop, dataref_t *dr)
{
        dedup_entry_t   *dde;

        if (ddt->cur_ddt_size >= ddt->max_ddt_size) {
                if (ddt->ddt_full == B_FALSE) {
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "Dedup table full.  Deduplication will continue "
                            "with existing table entries"));
                        ddt->ddt_full = B_TRUE;
                }
                return;
        }

        if ((dde = umem_cache_alloc(ddt->ddecache, UMEM_DEFAULT))
            != NULL) {
                assert(*ddepp == NULL);
                dde->dde_next = NULL;
                dde->dde_chksum = *cs;
                dde->dde_prop = prop;
                dde->dde_ref = *dr;
                *ddepp = dde;
                ddt->cur_ddt_size += sizeof (dedup_entry_t);
                ddt->ddt_count++;
        }
}

/*
 * Using the specified dedup table, do a lookup for an entry with
 * the checksum cs.  If found, return the block's reference info
 * in *dr. Otherwise, insert a new entry in the dedup table, using
 * the reference information specified by *dr.
 *
 * return value:  true - entry was found
 *                false - entry was not found
 */
static boolean_t
ddt_update(libzfs_handle_t *hdl, dedup_table_t *ddt, zio_cksum_t *cs,
    uint64_t prop, dataref_t *dr)
{
        uint32_t hashcode;
        dedup_entry_t **ddepp;

        hashcode = BF64_GET(cs->zc_word[0], 0, ddt->numhashbits);

        for (ddepp = &(ddt->dedup_hash_array[hashcode]); *ddepp != NULL;
            ddepp = &((*ddepp)->dde_next)) {
                if (ZIO_CHECKSUM_EQUAL(((*ddepp)->dde_chksum), *cs) &&
                    (*ddepp)->dde_prop == prop) {
                        *dr = (*ddepp)->dde_ref;
                        return (B_TRUE);
                }
        }
        ddt_hash_append(hdl, ddt, ddepp, cs, prop, dr);
        return (B_FALSE);
}

static int
dump_record(dmu_replay_record_t *drr, void *payload, int payload_len,
    zio_cksum_t *zc, int outfd)
{
        ASSERT3U(offsetof(dmu_replay_record_t, drr_u.drr_checksum.drr_checksum),
            ==, sizeof (dmu_replay_record_t) - sizeof (zio_cksum_t));
        fletcher_4_incremental_native(drr,
            offsetof(dmu_replay_record_t, drr_u.drr_checksum.drr_checksum), zc);
        if (drr->drr_type != DRR_BEGIN) {
                ASSERT(ZIO_CHECKSUM_IS_ZERO(&drr->drr_u.
                    drr_checksum.drr_checksum));
                drr->drr_u.drr_checksum.drr_checksum = *zc;
        }
        fletcher_4_incremental_native(&drr->drr_u.drr_checksum.drr_checksum,
            sizeof (zio_cksum_t), zc);
        if (write(outfd, drr, sizeof (*drr)) == -1)
                return (errno);
        if (payload_len != 0) {
                fletcher_4_incremental_native(payload, payload_len, zc);
                if (write(outfd, payload, payload_len) == -1)
                        return (errno);
        }
        return (0);
}

/*
 * This function is started in a separate thread when the dedup option
 * has been requested.  The main send thread determines the list of
 * snapshots to be included in the send stream and makes the ioctl calls
 * for each one.  But instead of having the ioctl send the output to the
 * the output fd specified by the caller of zfs_send()), the
 * ioctl is told to direct the output to a pipe, which is read by the
 * alternate thread running THIS function.  This function does the
 * dedup'ing by:
 *  1. building a dedup table (the DDT)
 *  2. doing checksums on each data block and inserting a record in the DDT
 *  3. looking for matching checksums, and
 *  4.  sending a DRR_WRITE_BYREF record instead of a write record whenever
 *      a duplicate block is found.
 * The output of this function then goes to the output fd requested
 * by the caller of zfs_send().
 */
static void *
cksummer(void *arg)
{
        dedup_arg_t *dda = arg;
        char *buf = zfs_alloc(dda->dedup_hdl, SPA_MAXBLOCKSIZE);
        dmu_replay_record_t thedrr = { 0 };
        dmu_replay_record_t *drr = &thedrr;
        FILE *ofp;
        int outfd;
        dedup_table_t ddt;
        zio_cksum_t stream_cksum;
        uint64_t numbuckets;

#ifdef _ILP32
        ddt.max_ddt_size = SMALLEST_POSSIBLE_MAX_DDT_MB << 20;
#else
        uint64_t physmem = sysconf(_SC_PHYS_PAGES) * sysconf(_SC_PAGESIZE);
        ddt.max_ddt_size =
            MAX((physmem * MAX_DDT_PHYSMEM_PERCENT) / 100,
            SMALLEST_POSSIBLE_MAX_DDT_MB << 20);
#endif

        numbuckets = ddt.max_ddt_size / (sizeof (dedup_entry_t));

        /*
         * numbuckets must be a power of 2.  Increase number to
         * a power of 2 if necessary.
         */
        if (!ISP2(numbuckets))
                numbuckets = 1ULL << high_order_bit(numbuckets);

        ddt.dedup_hash_array = calloc(numbuckets, sizeof (dedup_entry_t *));
        ddt.ddecache = umem_cache_create("dde", sizeof (dedup_entry_t), 0,
            NULL, NULL, NULL, NULL, NULL, 0);
        ddt.cur_ddt_size = numbuckets * sizeof (dedup_entry_t *);
        ddt.numhashbits = high_order_bit(numbuckets) - 1;
        ddt.ddt_full = B_FALSE;

        outfd = dda->outputfd;
        ofp = fdopen(dda->inputfd, "r");
        while (ssread(drr, sizeof (*drr), ofp) != 0) {

                /*
                 * kernel filled in checksum, we are going to write same
                 * record, but need to regenerate checksum.
                 */
                if (drr->drr_type != DRR_BEGIN) {
                        bzero(&drr->drr_u.drr_checksum.drr_checksum,
                            sizeof (drr->drr_u.drr_checksum.drr_checksum));
                }

                switch (drr->drr_type) {
                case DRR_BEGIN:
                {
                        struct drr_begin *drrb = &drr->drr_u.drr_begin;
                        int fflags;
                        int sz = 0;
                        ZIO_SET_CHECKSUM(&stream_cksum, 0, 0, 0, 0);

                        ASSERT3U(drrb->drr_magic, ==, DMU_BACKUP_MAGIC);

                        /* set the DEDUP feature flag for this stream */
                        fflags = DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo);
                        fflags |= (DMU_BACKUP_FEATURE_DEDUP |
                            DMU_BACKUP_FEATURE_DEDUPPROPS);
                        DMU_SET_FEATUREFLAGS(drrb->drr_versioninfo, fflags);

                        if (drr->drr_payloadlen != 0) {
                                sz = drr->drr_payloadlen;

                                if (sz > SPA_MAXBLOCKSIZE) {
                                        buf = zfs_realloc(dda->dedup_hdl, buf,
                                            SPA_MAXBLOCKSIZE, sz);
                                }
                                (void) ssread(buf, sz, ofp);
                                if (ferror(stdin))
                                        perror("fread");
                        }
                        if (dump_record(drr, buf, sz, &stream_cksum,
                            outfd) != 0)
                                goto out;
                        break;
                }

                case DRR_END:
                {
                        struct drr_end *drre = &drr->drr_u.drr_end;
                        /* use the recalculated checksum */
                        drre->drr_checksum = stream_cksum;
                        if (dump_record(drr, NULL, 0, &stream_cksum,
                            outfd) != 0)
                                goto out;
                        break;
                }

                case DRR_OBJECT:
                {
                        struct drr_object *drro = &drr->drr_u.drr_object;
                        if (drro->drr_bonuslen > 0) {
                                (void) ssread(buf,
                                    P2ROUNDUP((uint64_t)drro->drr_bonuslen, 8),
                                    ofp);
                        }
                        if (dump_record(drr, buf,
                            P2ROUNDUP((uint64_t)drro->drr_bonuslen, 8),
                            &stream_cksum, outfd) != 0)
                                goto out;
                        break;
                }

                case DRR_SPILL:
                {
                        struct drr_spill *drrs = &drr->drr_u.drr_spill;
                        (void) ssread(buf, drrs->drr_length, ofp);
                        if (dump_record(drr, buf, drrs->drr_length,
                            &stream_cksum, outfd) != 0)
                                goto out;
                        break;
                }

                case DRR_FREEOBJECTS:
                {
                        if (dump_record(drr, NULL, 0, &stream_cksum,
                            outfd) != 0)
                                goto out;
                        break;
                }

                case DRR_WRITE:
                {
                        struct drr_write *drrw = &drr->drr_u.drr_write;
                        dataref_t       dataref;
                        uint64_t        payload_size;

                        payload_size = DRR_WRITE_PAYLOAD_SIZE(drrw);
                        (void) ssread(buf, payload_size, ofp);

                        /*
                         * Use the existing checksum if it's dedup-capable,
                         * else calculate a SHA256 checksum for it.
                         */

                        if (ZIO_CHECKSUM_EQUAL(drrw->drr_key.ddk_cksum,
                            zero_cksum) ||
                            !DRR_IS_DEDUP_CAPABLE(drrw->drr_checksumflags)) {
                                SHA2_CTX ctx;
                                zio_cksum_t tmpsha256;

                                SHA2Init(SHA256, &ctx);
                                SHA2Update(&ctx, buf, payload_size);
                                SHA2Final(&tmpsha256, &ctx);

                                drrw->drr_key.ddk_cksum.zc_word[0] =
                                    BE_64(tmpsha256.zc_word[0]);
                                drrw->drr_key.ddk_cksum.zc_word[1] =
                                    BE_64(tmpsha256.zc_word[1]);
                                drrw->drr_key.ddk_cksum.zc_word[2] =
                                    BE_64(tmpsha256.zc_word[2]);
                                drrw->drr_key.ddk_cksum.zc_word[3] =
                                    BE_64(tmpsha256.zc_word[3]);
                                drrw->drr_checksumtype = ZIO_CHECKSUM_SHA256;
                                drrw->drr_checksumflags = DRR_CHECKSUM_DEDUP;
                        }

                        dataref.ref_guid = drrw->drr_toguid;
                        dataref.ref_object = drrw->drr_object;
                        dataref.ref_offset = drrw->drr_offset;

                        if (ddt_update(dda->dedup_hdl, &ddt,
                            &drrw->drr_key.ddk_cksum, drrw->drr_key.ddk_prop,
                            &dataref)) {
                                dmu_replay_record_t wbr_drr = {0};
                                struct drr_write_byref *wbr_drrr =
                                    &wbr_drr.drr_u.drr_write_byref;

                                /* block already present in stream */
                                wbr_drr.drr_type = DRR_WRITE_BYREF;

                                wbr_drrr->drr_object = drrw->drr_object;
                                wbr_drrr->drr_offset = drrw->drr_offset;
                                wbr_drrr->drr_length = drrw->drr_logical_size;
                                wbr_drrr->drr_toguid = drrw->drr_toguid;
                                wbr_drrr->drr_refguid = dataref.ref_guid;
                                wbr_drrr->drr_refobject =
                                    dataref.ref_object;
                                wbr_drrr->drr_refoffset =
                                    dataref.ref_offset;

                                wbr_drrr->drr_checksumtype =
                                    drrw->drr_checksumtype;
                                wbr_drrr->drr_checksumflags =
                                    drrw->drr_checksumtype;
                                wbr_drrr->drr_key.ddk_cksum =
                                    drrw->drr_key.ddk_cksum;
                                wbr_drrr->drr_key.ddk_prop =
                                    drrw->drr_key.ddk_prop;

                                if (dump_record(&wbr_drr, NULL, 0,
                                    &stream_cksum, outfd) != 0)
                                        goto out;
                        } else {
                                /* block not previously seen */
                                if (dump_record(drr, buf, payload_size,
                                    &stream_cksum, outfd) != 0)
                                        goto out;
                        }
                        break;
                }

                case DRR_WRITE_EMBEDDED:
                {
                        struct drr_write_embedded *drrwe =
                            &drr->drr_u.drr_write_embedded;
                        (void) ssread(buf,
                            P2ROUNDUP((uint64_t)drrwe->drr_psize, 8), ofp);
                        if (dump_record(drr, buf,
                            P2ROUNDUP((uint64_t)drrwe->drr_psize, 8),
                            &stream_cksum, outfd) != 0)
                                goto out;
                        break;
                }

                case DRR_FREE:
                {
                        if (dump_record(drr, NULL, 0, &stream_cksum,
                            outfd) != 0)
                                goto out;
                        break;
                }

                default:
                        (void) fprintf(stderr, "INVALID record type 0x%x\n",
                            drr->drr_type);
                        /* should never happen, so assert */
                        assert(B_FALSE);
                }
        }
out:
        umem_cache_destroy(ddt.ddecache);
        free(ddt.dedup_hash_array);
        free(buf);
        (void) fclose(ofp);

        return (NULL);
}

/*
 * Routines for dealing with the AVL tree of fs-nvlists
 */
typedef struct fsavl_node {
        avl_node_t fn_node;
        nvlist_t *fn_nvfs;
        char *fn_snapname;
        uint64_t fn_guid;
} fsavl_node_t;

static int
fsavl_compare(const void *arg1, const void *arg2)
{
        const fsavl_node_t *fn1 = (const fsavl_node_t *)arg1;
        const fsavl_node_t *fn2 = (const fsavl_node_t *)arg2;

        return (AVL_CMP(fn1->fn_guid, fn2->fn_guid));
}

/*
 * Given the GUID of a snapshot, find its containing filesystem and
 * (optionally) name.
 */
static nvlist_t *
fsavl_find(avl_tree_t *avl, uint64_t snapguid, char **snapname)
{
        fsavl_node_t fn_find;
        fsavl_node_t *fn;

        fn_find.fn_guid = snapguid;

        fn = avl_find(avl, &fn_find, NULL);
        if (fn) {
                if (snapname)
                        *snapname = fn->fn_snapname;
                return (fn->fn_nvfs);
        }
        return (NULL);
}

static void
fsavl_destroy(avl_tree_t *avl)
{
        fsavl_node_t *fn;
        void *cookie;

        if (avl == NULL)
                return;

        cookie = NULL;
        while ((fn = avl_destroy_nodes(avl, &cookie)) != NULL)
                free(fn);
        avl_destroy(avl);
        free(avl);
}

/*
 * Given an nvlist, produce an avl tree of snapshots, ordered by guid
 */
static avl_tree_t *
fsavl_create(nvlist_t *fss)
{
        avl_tree_t *fsavl;
        nvpair_t *fselem = NULL;

        if ((fsavl = malloc(sizeof (avl_tree_t))) == NULL)
                return (NULL);

        avl_create(fsavl, fsavl_compare, sizeof (fsavl_node_t),
            offsetof(fsavl_node_t, fn_node));

        while ((fselem = nvlist_next_nvpair(fss, fselem)) != NULL) {
                nvlist_t *nvfs, *snaps;
                nvpair_t *snapelem = NULL;

                VERIFY(0 == nvpair_value_nvlist(fselem, &nvfs));
                VERIFY(0 == nvlist_lookup_nvlist(nvfs, "snaps", &snaps));

                while ((snapelem =
                    nvlist_next_nvpair(snaps, snapelem)) != NULL) {
                        fsavl_node_t *fn;
                        uint64_t guid;

                        VERIFY(0 == nvpair_value_uint64(snapelem, &guid));
                        if ((fn = malloc(sizeof (fsavl_node_t))) == NULL) {
                                fsavl_destroy(fsavl);
                                return (NULL);
                        }
                        fn->fn_nvfs = nvfs;
                        fn->fn_snapname = nvpair_name(snapelem);
                        fn->fn_guid = guid;

                        /*
                         * Note: if there are multiple snaps with the
                         * same GUID, we ignore all but one.
                         */
                        if (avl_find(fsavl, fn, NULL) == NULL)
                                avl_add(fsavl, fn);
                        else
                                free(fn);
                }
        }

        return (fsavl);
}

/*
 * Routines for dealing with the giant nvlist of fs-nvlists, etc.
 */
typedef struct send_data {
        /*
         * assigned inside every recursive call,
         * restored from *_save on return:
         *
         * guid of fromsnap snapshot in parent dataset
         * txg of fromsnap snapshot in current dataset
         * txg of tosnap snapshot in current dataset
         */

        uint64_t parent_fromsnap_guid;
        uint64_t fromsnap_txg;
        uint64_t tosnap_txg;

        /* the nvlists get accumulated during depth-first traversal */
        nvlist_t *parent_snaps;
        nvlist_t *fss;
        nvlist_t *snapprops;

        /* send-receive configuration, does not change during traversal */
        const char *fsname;
        const char *fromsnap;
        const char *tosnap;
        boolean_t recursive;
        boolean_t verbose;
        boolean_t seenfrom;
        boolean_t seento;

        /*
         * The header nvlist is of the following format:
         * {
         *   "tosnap" -> string
         *   "fromsnap" -> string (if incremental)
         *   "fss" -> {
         *      id -> {
         *
         *       "name" -> string (full name; for debugging)
         *       "parentfromsnap" -> number (guid of fromsnap in parent)
         *
         *       "props" -> { name -> value (only if set here) }
         *       "snaps" -> { name (lastname) -> number (guid) }
         *       "snapprops" -> { name (lastname) -> { name -> value } }
         *
         *       "origin" -> number (guid) (if clone)
         *       "sent" -> boolean (not on-disk)
         *      }
         *   }
         * }
         *
         */
} send_data_t;

static void send_iterate_prop(zfs_handle_t *zhp, nvlist_t *nv);

static int
send_iterate_snap(zfs_handle_t *zhp, void *arg)
{
        send_data_t *sd = arg;
        uint64_t guid = zhp->zfs_dmustats.dds_guid;
        uint64_t txg = zhp->zfs_dmustats.dds_creation_txg;
        char *snapname;
        nvlist_t *nv;
        boolean_t isfromsnap, istosnap, istosnapwithnofrom;

        snapname = strrchr(zhp->zfs_name, '@')+1;
        isfromsnap = (sd->fromsnap != NULL &&
            strcmp(sd->fromsnap, snapname) == 0);
        istosnap = (sd->tosnap != NULL && (strcmp(sd->tosnap, snapname) == 0));
        istosnapwithnofrom = (istosnap && sd->fromsnap == NULL);

        if (sd->tosnap_txg != 0 && txg > sd->tosnap_txg) {
                if (sd->verbose) {
                        (void) fprintf(stderr, dgettext(TEXT_DOMAIN,
                            "skipping snapshot %s because it was created "
                            "after the destination snapshot (%s)\n"),
                            zhp->zfs_name, sd->tosnap);
                }
                zfs_close(zhp);
                return (0);
        }

        VERIFY(0 == nvlist_add_uint64(sd->parent_snaps, snapname, guid));
        /*
         * NB: if there is no fromsnap here (it's a newly created fs in
         * an incremental replication), we will substitute the tosnap.
         */
        if (isfromsnap || (sd->parent_fromsnap_guid == 0 && istosnap)) {
                sd->parent_fromsnap_guid = guid;
        }

        if (!sd->recursive) {
                if (!sd->seenfrom && isfromsnap) {
                        sd->seenfrom = B_TRUE;
                        zfs_close(zhp);
                        return (0);
                }

                if ((sd->seento || !sd->seenfrom) && !istosnapwithnofrom) {
                        zfs_close(zhp);
                        return (0);
                }

                if (istosnap)
                        sd->seento = B_TRUE;
        }

        VERIFY(0 == nvlist_alloc(&nv, NV_UNIQUE_NAME, 0));
        send_iterate_prop(zhp, nv);
        VERIFY(0 == nvlist_add_nvlist(sd->snapprops, snapname, nv));
        nvlist_free(nv);

        zfs_close(zhp);
        return (0);
}

static void
send_iterate_prop(zfs_handle_t *zhp, nvlist_t *nv)
{
        nvpair_t *elem = NULL;

        while ((elem = nvlist_next_nvpair(zhp->zfs_props, elem)) != NULL) {
                char *propname = nvpair_name(elem);
                zfs_prop_t prop = zfs_name_to_prop(propname);
                nvlist_t *propnv;

                if (!zfs_prop_user(propname)) {
                        /*
                         * Realistically, this should never happen.  However,
                         * we want the ability to add DSL properties without
                         * needing to make incompatible version changes.  We
                         * need to ignore unknown properties to allow older
                         * software to still send datasets containing these
                         * properties, with the unknown properties elided.
                         */
                        if (prop == ZPROP_INVAL)
                                continue;

                        if (zfs_prop_readonly(prop))
                                continue;
                }

                verify(nvpair_value_nvlist(elem, &propnv) == 0);
                if (prop == ZFS_PROP_QUOTA || prop == ZFS_PROP_RESERVATION ||
                    prop == ZFS_PROP_REFQUOTA ||
                    prop == ZFS_PROP_REFRESERVATION) {
                        char *source;
                        uint64_t value;
                        verify(nvlist_lookup_uint64(propnv,
                            ZPROP_VALUE, &value) == 0);
                        if (zhp->zfs_type == ZFS_TYPE_SNAPSHOT)
                                continue;
                        /*
                         * May have no source before SPA_VERSION_RECVD_PROPS,
                         * but is still modifiable.
                         */
                        if (nvlist_lookup_string(propnv,
                            ZPROP_SOURCE, &source) == 0) {
                                if ((strcmp(source, zhp->zfs_name) != 0) &&
                                    (strcmp(source,
                                    ZPROP_SOURCE_VAL_RECVD) != 0))
                                        continue;
                        }
                } else {
                        char *source;
                        if (nvlist_lookup_string(propnv,
                            ZPROP_SOURCE, &source) != 0)
                                continue;
                        if ((strcmp(source, zhp->zfs_name) != 0) &&
                            (strcmp(source, ZPROP_SOURCE_VAL_RECVD) != 0))
                                continue;
                }

                if (zfs_prop_user(propname) ||
                    zfs_prop_get_type(prop) == PROP_TYPE_STRING) {
                        char *value;
                        verify(nvlist_lookup_string(propnv,
                            ZPROP_VALUE, &value) == 0);
                        VERIFY(0 == nvlist_add_string(nv, propname, value));
                } else {
                        uint64_t value;
                        verify(nvlist_lookup_uint64(propnv,
                            ZPROP_VALUE, &value) == 0);
                        VERIFY(0 == nvlist_add_uint64(nv, propname, value));
                }
        }
}

/*
 * returns snapshot creation txg
 * and returns 0 if the snapshot does not exist
 */
static uint64_t
get_snap_txg(libzfs_handle_t *hdl, const char *fs, const char *snap)
{
        char name[ZFS_MAX_DATASET_NAME_LEN];
        uint64_t txg = 0;

        if (fs == NULL || fs[0] == '\0' || snap == NULL || snap[0] == '\0')
                return (txg);

        (void) snprintf(name, sizeof (name), "%s@%s", fs, snap);
        if (zfs_dataset_exists(hdl, name, ZFS_TYPE_SNAPSHOT)) {
                zfs_handle_t *zhp = zfs_open(hdl, name, ZFS_TYPE_SNAPSHOT);
                if (zhp != NULL) {
                        txg = zfs_prop_get_int(zhp, ZFS_PROP_CREATETXG);
                        zfs_close(zhp);
                }
        }

        return (txg);
}

/*
 * recursively generate nvlists describing datasets.  See comment
 * for the data structure send_data_t above for description of contents
 * of the nvlist.
 */
static int
send_iterate_fs(zfs_handle_t *zhp, void *arg)
{
        send_data_t *sd = arg;
        nvlist_t *nvfs, *nv;
        int rv = 0;
        uint64_t parent_fromsnap_guid_save = sd->parent_fromsnap_guid;
        uint64_t fromsnap_txg_save = sd->fromsnap_txg;
        uint64_t tosnap_txg_save = sd->tosnap_txg;
        uint64_t txg = zhp->zfs_dmustats.dds_creation_txg;
        uint64_t guid = zhp->zfs_dmustats.dds_guid;
        uint64_t fromsnap_txg, tosnap_txg;
        char guidstring[64];

        fromsnap_txg = get_snap_txg(zhp->zfs_hdl, zhp->zfs_name, sd->fromsnap);
        if (fromsnap_txg != 0)
                sd->fromsnap_txg = fromsnap_txg;

        tosnap_txg = get_snap_txg(zhp->zfs_hdl, zhp->zfs_name, sd->tosnap);
        if (tosnap_txg != 0)
                sd->tosnap_txg = tosnap_txg;

        /*
         * on the send side, if the current dataset does not have tosnap,
         * perform two additional checks:
         *
         * - skip sending the current dataset if it was created later than
         *   the parent tosnap
         * - return error if the current dataset was created earlier than
         *   the parent tosnap
         */
        if (sd->tosnap != NULL && tosnap_txg == 0) {
                if (sd->tosnap_txg != 0 && txg > sd->tosnap_txg) {
                        if (sd->verbose) {
                                (void) fprintf(stderr, dgettext(TEXT_DOMAIN,
                                    "skipping dataset %s: snapshot %s does "
                                    "not exist\n"), zhp->zfs_name, sd->tosnap);
                        }
                } else {
                        (void) fprintf(stderr, dgettext(TEXT_DOMAIN,
                            "cannot send %s@%s%s: snapshot %s@%s does not "
                            "exist\n"), sd->fsname, sd->tosnap, sd->recursive ?
                            dgettext(TEXT_DOMAIN, " recursively") : "",
                            zhp->zfs_name, sd->tosnap);
                        rv = -1;
                }
                goto out;
        }

        VERIFY(0 == nvlist_alloc(&nvfs, NV_UNIQUE_NAME, 0));
        VERIFY(0 == nvlist_add_string(nvfs, "name", zhp->zfs_name));
        VERIFY(0 == nvlist_add_uint64(nvfs, "parentfromsnap",
            sd->parent_fromsnap_guid));

        if (zhp->zfs_dmustats.dds_origin[0]) {
                zfs_handle_t *origin = zfs_open(zhp->zfs_hdl,
                    zhp->zfs_dmustats.dds_origin, ZFS_TYPE_SNAPSHOT);
                if (origin == NULL) {
                        rv = -1;
                        goto out;
                }
                VERIFY(0 == nvlist_add_uint64(nvfs, "origin",
                    origin->zfs_dmustats.dds_guid));
        }

        /* iterate over props */
        VERIFY(0 == nvlist_alloc(&nv, NV_UNIQUE_NAME, 0));
        send_iterate_prop(zhp, nv);
        VERIFY(0 == nvlist_add_nvlist(nvfs, "props", nv));
        nvlist_free(nv);

        /* iterate over snaps, and set sd->parent_fromsnap_guid */
        sd->parent_fromsnap_guid = 0;
        VERIFY(0 == nvlist_alloc(&sd->parent_snaps, NV_UNIQUE_NAME, 0));
        VERIFY(0 == nvlist_alloc(&sd->snapprops, NV_UNIQUE_NAME, 0));
        (void) zfs_iter_snapshots_sorted(zhp, send_iterate_snap, sd);
        VERIFY(0 == nvlist_add_nvlist(nvfs, "snaps", sd->parent_snaps));
        VERIFY(0 == nvlist_add_nvlist(nvfs, "snapprops", sd->snapprops));
        nvlist_free(sd->parent_snaps);
        nvlist_free(sd->snapprops);

        /* add this fs to nvlist */
        (void) snprintf(guidstring, sizeof (guidstring),
            "0x%llx", (longlong_t)guid);
        VERIFY(0 == nvlist_add_nvlist(sd->fss, guidstring, nvfs));
        nvlist_free(nvfs);

        /* iterate over children */
        if (sd->recursive)
                rv = zfs_iter_filesystems(zhp, send_iterate_fs, sd);

out:
        sd->parent_fromsnap_guid = parent_fromsnap_guid_save;
        sd->fromsnap_txg = fromsnap_txg_save;
        sd->tosnap_txg = tosnap_txg_save;

        zfs_close(zhp);
        return (rv);
}

static int
gather_nvlist(libzfs_handle_t *hdl, const char *fsname, const char *fromsnap,
    const char *tosnap, boolean_t recursive, boolean_t verbose,
    nvlist_t **nvlp, avl_tree_t **avlp)
{
        zfs_handle_t *zhp;
        send_data_t sd = { 0 };
        int error;

        zhp = zfs_open(hdl, fsname, ZFS_TYPE_FILESYSTEM | ZFS_TYPE_VOLUME);
        if (zhp == NULL)
                return (EZFS_BADTYPE);

        VERIFY(0 == nvlist_alloc(&sd.fss, NV_UNIQUE_NAME, 0));
        sd.fsname = fsname;
        sd.fromsnap = fromsnap;
        sd.tosnap = tosnap;
        sd.recursive = recursive;
        sd.verbose = verbose;

        if ((error = send_iterate_fs(zhp, &sd)) != 0) {
                nvlist_free(sd.fss);
                if (avlp != NULL)
                        *avlp = NULL;
                *nvlp = NULL;
                return (error);
        }

        if (avlp != NULL && (*avlp = fsavl_create(sd.fss)) == NULL) {
                nvlist_free(sd.fss);
                *nvlp = NULL;
                return (EZFS_NOMEM);
        }

        *nvlp = sd.fss;
        return (0);
}

/*
 * Routines specific to "zfs send"
 */
typedef struct send_dump_data {
        /* these are all just the short snapname (the part after the @) */
        const char *fromsnap;
        const char *tosnap;
        char prevsnap[ZFS_MAX_DATASET_NAME_LEN];
        uint64_t prevsnap_obj;
        boolean_t seenfrom, seento, replicate, doall, fromorigin;
        boolean_t verbose, dryrun, parsable, progress, embed_data, std_out;
        boolean_t large_block, compress;
        int outfd;
        boolean_t err;
        nvlist_t *fss;
        nvlist_t *snapholds;
        avl_tree_t *fsavl;
        snapfilter_cb_t *filter_cb;
        void *filter_cb_arg;
        nvlist_t *debugnv;
        char holdtag[ZFS_MAX_DATASET_NAME_LEN];
        int cleanup_fd;
        uint64_t size;
} send_dump_data_t;

static int
estimate_ioctl(zfs_handle_t *zhp, uint64_t fromsnap_obj,
    boolean_t fromorigin, enum lzc_send_flags flags, uint64_t *sizep)
{
        zfs_cmd_t zc = {"\0"};
        libzfs_handle_t *hdl = zhp->zfs_hdl;

        assert(zhp->zfs_type == ZFS_TYPE_SNAPSHOT);
        assert(fromsnap_obj == 0 || !fromorigin);

        (void) strlcpy(zc.zc_name, zhp->zfs_name, sizeof (zc.zc_name));
        zc.zc_obj = fromorigin;
        zc.zc_sendobj = zfs_prop_get_int(zhp, ZFS_PROP_OBJSETID);
        zc.zc_fromobj = fromsnap_obj;
        zc.zc_guid = 1;  /* estimate flag */
        zc.zc_flags = flags;

        if (zfs_ioctl(zhp->zfs_hdl, ZFS_IOC_SEND, &zc) != 0) {
                char errbuf[1024];
                (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
                    "warning: cannot estimate space for '%s'"), zhp->zfs_name);

                switch (errno) {
                case EXDEV:
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "not an earlier snapshot from the same fs"));
                        return (zfs_error(hdl, EZFS_CROSSTARGET, errbuf));

                case ENOENT:
                        if (zfs_dataset_exists(hdl, zc.zc_name,
                            ZFS_TYPE_SNAPSHOT)) {
                                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                                    "incremental source (@%s) does not exist"),
                                    zc.zc_value);
                        }
                        return (zfs_error(hdl, EZFS_NOENT, errbuf));

                case EDQUOT:
                case EFBIG:
                case EIO:
                case ENOLINK:
                case ENOSPC:
                case ENOSTR:
                case ENXIO:
                case EPIPE:
                case ERANGE:
                case EFAULT:
                case EROFS:
                        zfs_error_aux(hdl, strerror(errno));
                        return (zfs_error(hdl, EZFS_BADBACKUP, errbuf));

                default:
                        return (zfs_standard_error(hdl, errno, errbuf));
                }
        }

        *sizep = zc.zc_objset_type;

        return (0);
}

/*
 * Dumps a backup of the given snapshot (incremental from fromsnap if it's not
 * NULL) to the file descriptor specified by outfd.
 */
static int
dump_ioctl(zfs_handle_t *zhp, const char *fromsnap, uint64_t fromsnap_obj,
    boolean_t fromorigin, int outfd, enum lzc_send_flags flags,
    nvlist_t *debugnv)
{
        zfs_cmd_t zc = {"\0"};
        libzfs_handle_t *hdl = zhp->zfs_hdl;
        nvlist_t *thisdbg;

        assert(zhp->zfs_type == ZFS_TYPE_SNAPSHOT);
        assert(fromsnap_obj == 0 || !fromorigin);

        (void) strlcpy(zc.zc_name, zhp->zfs_name, sizeof (zc.zc_name));
        zc.zc_cookie = outfd;
        zc.zc_obj = fromorigin;
        zc.zc_sendobj = zfs_prop_get_int(zhp, ZFS_PROP_OBJSETID);
        zc.zc_fromobj = fromsnap_obj;
        zc.zc_flags = flags;

        VERIFY(0 == nvlist_alloc(&thisdbg, NV_UNIQUE_NAME, 0));
        if (fromsnap && fromsnap[0] != '\0') {
                VERIFY(0 == nvlist_add_string(thisdbg,
                    "fromsnap", fromsnap));
        }

        if (zfs_ioctl(zhp->zfs_hdl, ZFS_IOC_SEND, &zc) != 0) {
                char errbuf[1024];
                (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
                    "warning: cannot send '%s'"), zhp->zfs_name);

                VERIFY(0 == nvlist_add_uint64(thisdbg, "error", errno));
                if (debugnv) {
                        VERIFY(0 == nvlist_add_nvlist(debugnv,
                            zhp->zfs_name, thisdbg));
                }
                nvlist_free(thisdbg);

                switch (errno) {
                case EXDEV:
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "not an earlier snapshot from the same fs"));
                        return (zfs_error(hdl, EZFS_CROSSTARGET, errbuf));

                case ENOENT:
                        if (zfs_dataset_exists(hdl, zc.zc_name,
                            ZFS_TYPE_SNAPSHOT)) {
                                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                                    "incremental source (@%s) does not exist"),
                                    zc.zc_value);
                        }
                        return (zfs_error(hdl, EZFS_NOENT, errbuf));

                case EDQUOT:
                case EFBIG:
                case EIO:
                case ENOLINK:
                case ENOSPC:
                case ENOSTR:
                case ENXIO:
                case EPIPE:
                case ERANGE:
                case EFAULT:
                case EROFS:
                        zfs_error_aux(hdl, strerror(errno));
                        return (zfs_error(hdl, EZFS_BADBACKUP, errbuf));

                default:
                        return (zfs_standard_error(hdl, errno, errbuf));
                }
        }

        if (debugnv)
                VERIFY(0 == nvlist_add_nvlist(debugnv, zhp->zfs_name, thisdbg));
        nvlist_free(thisdbg);

        return (0);
}

static void
gather_holds(zfs_handle_t *zhp, send_dump_data_t *sdd)
{
        assert(zhp->zfs_type == ZFS_TYPE_SNAPSHOT);

        /*
         * zfs_send() only sets snapholds for sends that need them,
         * e.g. replication and doall.
         */
        if (sdd->snapholds == NULL)
                return;

        fnvlist_add_string(sdd->snapholds, zhp->zfs_name, sdd->holdtag);
}

static void *
send_progress_thread(void *arg)
{
        progress_arg_t *pa = arg;
        zfs_cmd_t zc = {"\0"};
        zfs_handle_t *zhp = pa->pa_zhp;
        libzfs_handle_t *hdl = zhp->zfs_hdl;
        unsigned long long bytes;
        char buf[16];
        time_t t;
        struct tm *tm;

        (void) strlcpy(zc.zc_name, zhp->zfs_name, sizeof (zc.zc_name));

        if (!pa->pa_parsable)
                (void) fprintf(stderr, "TIME        SENT   SNAPSHOT\n");

        /*
         * Print the progress from ZFS_IOC_SEND_PROGRESS every second.
         */
        for (;;) {
                (void) sleep(1);

                zc.zc_cookie = pa->pa_fd;
                if (zfs_ioctl(hdl, ZFS_IOC_SEND_PROGRESS, &zc) != 0)
                        return ((void *)-1);

                (void) time(&t);
                tm = localtime(&t);
                bytes = zc.zc_cookie;

                if (pa->pa_parsable) {
                        (void) fprintf(stderr, "%02d:%02d:%02d\t%llu\t%s\n",
                            tm->tm_hour, tm->tm_min, tm->tm_sec,
                            bytes, zhp->zfs_name);
                } else {
                        zfs_nicenum(bytes, buf, sizeof (buf));
                        (void) fprintf(stderr, "%02d:%02d:%02d   %5s   %s\n",
                            tm->tm_hour, tm->tm_min, tm->tm_sec,
                            buf, zhp->zfs_name);
                }
        }
}

static void
send_print_verbose(FILE *fout, const char *tosnap, const char *fromsnap,
    uint64_t size, boolean_t parsable)
{
        if (parsable) {
                if (fromsnap != NULL) {
                        (void) fprintf(fout, "incremental\t%s\t%s",
                            fromsnap, tosnap);
                } else {
                        (void) fprintf(fout, "full\t%s",
                            tosnap);
                }
        } else {
                if (fromsnap != NULL) {
                        if (strchr(fromsnap, '@') == NULL &&
                            strchr(fromsnap, '#') == NULL) {
                                (void) fprintf(fout, dgettext(TEXT_DOMAIN,
                                    "send from @%s to %s"),
                                    fromsnap, tosnap);
                        } else {
                                (void) fprintf(fout, dgettext(TEXT_DOMAIN,
                                    "send from %s to %s"),
                                    fromsnap, tosnap);
                        }
                } else {
                        (void) fprintf(fout, dgettext(TEXT_DOMAIN,
                            "full send of %s"),
                            tosnap);
                }
        }

        if (size != 0) {
                if (parsable) {
                        (void) fprintf(fout, "\t%llu",
                            (longlong_t)size);
                } else {
                        char buf[16];
                        zfs_nicenum(size, buf, sizeof (buf));
                        (void) fprintf(fout, dgettext(TEXT_DOMAIN,
                            " estimated size is %s"), buf);
                }
        }
        (void) fprintf(fout, "\n");
}

static int
dump_snapshot(zfs_handle_t *zhp, void *arg)
{
        send_dump_data_t *sdd = arg;
        progress_arg_t pa = { 0 };
        pthread_t tid;
        char *thissnap;
        enum lzc_send_flags flags = 0;
        int err;
        boolean_t isfromsnap, istosnap, fromorigin;
        boolean_t exclude = B_FALSE;
        FILE *fout = sdd->std_out ? stdout : stderr;

        err = 0;
        thissnap = strchr(zhp->zfs_name, '@') + 1;
        isfromsnap = (sdd->fromsnap != NULL &&
            strcmp(sdd->fromsnap, thissnap) == 0);

        if (!sdd->seenfrom && isfromsnap) {
                gather_holds(zhp, sdd);
                sdd->seenfrom = B_TRUE;
                (void) strlcpy(sdd->prevsnap, thissnap,
                    sizeof (sdd->prevsnap));
                sdd->prevsnap_obj = zfs_prop_get_int(zhp, ZFS_PROP_OBJSETID);
                zfs_close(zhp);
                return (0);
        }

        if (sdd->seento || !sdd->seenfrom) {
                zfs_close(zhp);
                return (0);
        }

        istosnap = (strcmp(sdd->tosnap, thissnap) == 0);
        if (istosnap)
                sdd->seento = B_TRUE;

        if (sdd->large_block)
                flags |= LZC_SEND_FLAG_LARGE_BLOCK;
        if (sdd->embed_data)
                flags |= LZC_SEND_FLAG_EMBED_DATA;
        if (sdd->compress)
                flags |= LZC_SEND_FLAG_COMPRESS;

        if (!sdd->doall && !isfromsnap && !istosnap) {
                if (sdd->replicate) {
                        char *snapname;
                        nvlist_t *snapprops;
                        /*
                         * Filter out all intermediate snapshots except origin
                         * snapshots needed to replicate clones.
                         */
                        nvlist_t *nvfs = fsavl_find(sdd->fsavl,
                            zhp->zfs_dmustats.dds_guid, &snapname);

                        VERIFY(0 == nvlist_lookup_nvlist(nvfs,
                            "snapprops", &snapprops));
                        VERIFY(0 == nvlist_lookup_nvlist(snapprops,
                            thissnap, &snapprops));
                        exclude = !nvlist_exists(snapprops, "is_clone_origin");
                } else {
                        exclude = B_TRUE;
                }
        }

        /*
         * If a filter function exists, call it to determine whether
         * this snapshot will be sent.
         */
        if (exclude || (sdd->filter_cb != NULL &&
            sdd->filter_cb(zhp, sdd->filter_cb_arg) == B_FALSE)) {
                /*
                 * This snapshot is filtered out.  Don't send it, and don't
                 * set prevsnap_obj, so it will be as if this snapshot didn't
                 * exist, and the next accepted snapshot will be sent as
                 * an incremental from the last accepted one, or as the
                 * first (and full) snapshot in the case of a replication,
                 * non-incremental send.
                 */
                zfs_close(zhp);
                return (0);
        }

        gather_holds(zhp, sdd);
        fromorigin = sdd->prevsnap[0] == '\0' &&
            (sdd->fromorigin || sdd->replicate);

        if (sdd->verbose) {
                uint64_t size = 0;
                (void) estimate_ioctl(zhp, sdd->prevsnap_obj,
                    fromorigin, flags, &size);

                send_print_verbose(fout, zhp->zfs_name,
                    sdd->prevsnap[0] ? sdd->prevsnap : NULL,
                    size, sdd->parsable);
                sdd->size += size;
        }

        if (!sdd->dryrun) {
                /*
                 * If progress reporting is requested, spawn a new thread to
                 * poll ZFS_IOC_SEND_PROGRESS at a regular interval.
                 */
                if (sdd->progress) {
                        pa.pa_zhp = zhp;
                        pa.pa_fd = sdd->outfd;
                        pa.pa_parsable = sdd->parsable;

                        if ((err = pthread_create(&tid, NULL,
                            send_progress_thread, &pa))) {
                                zfs_close(zhp);
                                return (err);
                        }
                }

                err = dump_ioctl(zhp, sdd->prevsnap, sdd->prevsnap_obj,
                    fromorigin, sdd->outfd, flags, sdd->debugnv);

                if (sdd->progress) {
                        (void) pthread_cancel(tid);
                        (void) pthread_join(tid, NULL);
                }
        }

        (void) strcpy(sdd->prevsnap, thissnap);
        sdd->prevsnap_obj = zfs_prop_get_int(zhp, ZFS_PROP_OBJSETID);
        zfs_close(zhp);
        return (err);
}

static int
dump_filesystem(zfs_handle_t *zhp, void *arg)
{
        int rv = 0;
        send_dump_data_t *sdd = arg;
        boolean_t missingfrom = B_FALSE;
        zfs_cmd_t zc = {"\0"};

        (void) snprintf(zc.zc_name, sizeof (zc.zc_name), "%s@%s",
            zhp->zfs_name, sdd->tosnap);
        if (ioctl(zhp->zfs_hdl->libzfs_fd, ZFS_IOC_OBJSET_STATS, &zc) != 0) {
                (void) fprintf(stderr, dgettext(TEXT_DOMAIN,
                    "WARNING: could not send %s@%s: does not exist\n"),
                    zhp->zfs_name, sdd->tosnap);
                sdd->err = B_TRUE;
                return (0);
        }

        if (sdd->replicate && sdd->fromsnap) {
                /*
                 * If this fs does not have fromsnap, and we're doing
                 * recursive, we need to send a full stream from the
                 * beginning (or an incremental from the origin if this
                 * is a clone).  If we're doing non-recursive, then let
                 * them get the error.
                 */
                (void) snprintf(zc.zc_name, sizeof (zc.zc_name), "%s@%s",
                    zhp->zfs_name, sdd->fromsnap);
                if (ioctl(zhp->zfs_hdl->libzfs_fd,
                    ZFS_IOC_OBJSET_STATS, &zc) != 0) {
                        missingfrom = B_TRUE;
                }
        }

        sdd->seenfrom = sdd->seento = sdd->prevsnap[0] = 0;
        sdd->prevsnap_obj = 0;
        if (sdd->fromsnap == NULL || missingfrom)
                sdd->seenfrom = B_TRUE;

        rv = zfs_iter_snapshots_sorted(zhp, dump_snapshot, arg);
        if (!sdd->seenfrom) {
                (void) fprintf(stderr, dgettext(TEXT_DOMAIN,
                    "WARNING: could not send %s@%s:\n"
                    "incremental source (%s@%s) does not exist\n"),
                    zhp->zfs_name, sdd->tosnap,
                    zhp->zfs_name, sdd->fromsnap);
                sdd->err = B_TRUE;
        } else if (!sdd->seento) {
                if (sdd->fromsnap) {
                        (void) fprintf(stderr, dgettext(TEXT_DOMAIN,
                            "WARNING: could not send %s@%s:\n"
                            "incremental source (%s@%s) "
                            "is not earlier than it\n"),
                            zhp->zfs_name, sdd->tosnap,
                            zhp->zfs_name, sdd->fromsnap);
                } else {
                        (void) fprintf(stderr, dgettext(TEXT_DOMAIN,
                            "WARNING: "
                            "could not send %s@%s: does not exist\n"),
                            zhp->zfs_name, sdd->tosnap);
                }
                sdd->err = B_TRUE;
        }

        return (rv);
}

static int
dump_filesystems(zfs_handle_t *rzhp, void *arg)
{
        send_dump_data_t *sdd = arg;
        nvpair_t *fspair;
        boolean_t needagain, progress;

        if (!sdd->replicate)
                return (dump_filesystem(rzhp, sdd));

        /* Mark the clone origin snapshots. */
        for (fspair = nvlist_next_nvpair(sdd->fss, NULL); fspair;
            fspair = nvlist_next_nvpair(sdd->fss, fspair)) {
                nvlist_t *nvfs;
                uint64_t origin_guid = 0;

                VERIFY(0 == nvpair_value_nvlist(fspair, &nvfs));
                (void) nvlist_lookup_uint64(nvfs, "origin", &origin_guid);
                if (origin_guid != 0) {
                        char *snapname;
                        nvlist_t *origin_nv = fsavl_find(sdd->fsavl,
                            origin_guid, &snapname);
                        if (origin_nv != NULL) {
                                nvlist_t *snapprops;
                                VERIFY(0 == nvlist_lookup_nvlist(origin_nv,
                                    "snapprops", &snapprops));
                                VERIFY(0 == nvlist_lookup_nvlist(snapprops,
                                    snapname, &snapprops));
                                VERIFY(0 == nvlist_add_boolean(
                                    snapprops, "is_clone_origin"));
                        }
                }
        }
again:
        needagain = progress = B_FALSE;
        for (fspair = nvlist_next_nvpair(sdd->fss, NULL); fspair;
            fspair = nvlist_next_nvpair(sdd->fss, fspair)) {
                nvlist_t *fslist, *parent_nv;
                char *fsname;
                zfs_handle_t *zhp;
                int err;
                uint64_t origin_guid = 0;
                uint64_t parent_guid = 0;

                VERIFY(nvpair_value_nvlist(fspair, &fslist) == 0);
                if (nvlist_lookup_boolean(fslist, "sent") == 0)
                        continue;

                VERIFY(nvlist_lookup_string(fslist, "name", &fsname) == 0);
                (void) nvlist_lookup_uint64(fslist, "origin", &origin_guid);
                (void) nvlist_lookup_uint64(fslist, "parentfromsnap",
                    &parent_guid);

                if (parent_guid != 0) {
                        parent_nv = fsavl_find(sdd->fsavl, parent_guid, NULL);
                        if (!nvlist_exists(parent_nv, "sent")) {
                                /* parent has not been sent; skip this one */
                                needagain = B_TRUE;
                                continue;
                        }
                }

                if (origin_guid != 0) {
                        nvlist_t *origin_nv = fsavl_find(sdd->fsavl,
                            origin_guid, NULL);
                        if (origin_nv != NULL &&
                            !nvlist_exists(origin_nv, "sent")) {
                                /*
                                 * origin has not been sent yet;
                                 * skip this clone.
                                 */
                                needagain = B_TRUE;
                                continue;
                        }
                }

                zhp = zfs_open(rzhp->zfs_hdl, fsname, ZFS_TYPE_DATASET);
                if (zhp == NULL)
                        return (-1);
                err = dump_filesystem(zhp, sdd);
                VERIFY(nvlist_add_boolean(fslist, "sent") == 0);
                progress = B_TRUE;
                zfs_close(zhp);
                if (err)
                        return (err);
        }
        if (needagain) {
                assert(progress);
                goto again;
        }

        /* clean out the sent flags in case we reuse this fss */
        for (fspair = nvlist_next_nvpair(sdd->fss, NULL); fspair;
            fspair = nvlist_next_nvpair(sdd->fss, fspair)) {
                nvlist_t *fslist;

                VERIFY(nvpair_value_nvlist(fspair, &fslist) == 0);
                (void) nvlist_remove_all(fslist, "sent");
        }

        return (0);
}

nvlist_t *
zfs_send_resume_token_to_nvlist(libzfs_handle_t *hdl, const char *token)
{
        unsigned int version;
        int nread, i;
        unsigned long long checksum, packed_len;

        /*
         * Decode token header, which is:
         *   <token version>-<checksum of payload>-<uncompressed payload length>
         * Note that the only supported token version is 1.
         */
        nread = sscanf(token, "%u-%llx-%llx-",
            &version, &checksum, &packed_len);
        if (nread != 3) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "resume token is corrupt (invalid format)"));
                return (NULL);
        }

        if (version != ZFS_SEND_RESUME_TOKEN_VERSION) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "resume token is corrupt (invalid version %u)"),
                    version);
                return (NULL);
        }

        /* convert hexadecimal representation to binary */
        token = strrchr(token, '-') + 1;
        int len = strlen(token) / 2;
        unsigned char *compressed = zfs_alloc(hdl, len);
        for (i = 0; i < len; i++) {
                nread = sscanf(token + i * 2, "%2hhx", compressed + i);
                if (nread != 1) {
                        free(compressed);
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "resume token is corrupt "
                            "(payload is not hex-encoded)"));
                        return (NULL);
                }
        }

        /* verify checksum */
        zio_cksum_t cksum;
        fletcher_4_native_varsize(compressed, len, &cksum);
        if (cksum.zc_word[0] != checksum) {
                free(compressed);
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "resume token is corrupt (incorrect checksum)"));
                return (NULL);
        }

        /* uncompress */
        void *packed = zfs_alloc(hdl, packed_len);
        uLongf packed_len_long = packed_len;
        if (uncompress(packed, &packed_len_long, compressed, len) != Z_OK ||
            packed_len_long != packed_len) {
                free(packed);
                free(compressed);
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "resume token is corrupt (decompression failed)"));
                return (NULL);
        }

        /* unpack nvlist */
        nvlist_t *nv;
        int error = nvlist_unpack(packed, packed_len, &nv, KM_SLEEP);
        free(packed);
        free(compressed);
        if (error != 0) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "resume token is corrupt (nvlist_unpack failed)"));
                return (NULL);
        }
        return (nv);
}

int
zfs_send_resume(libzfs_handle_t *hdl, sendflags_t *flags, int outfd,
    const char *resume_token)
{
        char errbuf[1024];
        char *toname;
        char *fromname = NULL;
        uint64_t resumeobj, resumeoff, toguid, fromguid, bytes;
        zfs_handle_t *zhp;
        int error = 0;
        char name[ZFS_MAX_DATASET_NAME_LEN];
        enum lzc_send_flags lzc_flags = 0;

        (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
            "cannot resume send"));

        nvlist_t *resume_nvl =
            zfs_send_resume_token_to_nvlist(hdl, resume_token);
        if (resume_nvl == NULL) {
                /*
                 * zfs_error_aux has already been set by
                 * zfs_send_resume_token_to_nvlist
                 */
                return (zfs_error(hdl, EZFS_FAULT, errbuf));
        }
        if (flags->verbose) {
                (void) fprintf(stderr, dgettext(TEXT_DOMAIN,
                    "resume token contents:\n"));
                nvlist_print(stderr, resume_nvl);
        }

        if (nvlist_lookup_string(resume_nvl, "toname", &toname) != 0 ||
            nvlist_lookup_uint64(resume_nvl, "object", &resumeobj) != 0 ||
            nvlist_lookup_uint64(resume_nvl, "offset", &resumeoff) != 0 ||
            nvlist_lookup_uint64(resume_nvl, "bytes", &bytes) != 0 ||
            nvlist_lookup_uint64(resume_nvl, "toguid", &toguid) != 0) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "resume token is corrupt"));
                return (zfs_error(hdl, EZFS_FAULT, errbuf));
        }
        fromguid = 0;
        (void) nvlist_lookup_uint64(resume_nvl, "fromguid", &fromguid);

        if (flags->largeblock || nvlist_exists(resume_nvl, "largeblockok"))
                lzc_flags |= LZC_SEND_FLAG_LARGE_BLOCK;
        if (flags->embed_data || nvlist_exists(resume_nvl, "embedok"))
                lzc_flags |= LZC_SEND_FLAG_EMBED_DATA;
        if (flags->compress || nvlist_exists(resume_nvl, "compressok"))
                lzc_flags |= LZC_SEND_FLAG_COMPRESS;

        if (guid_to_name(hdl, toname, toguid, B_FALSE, name) != 0) {
                if (zfs_dataset_exists(hdl, toname, ZFS_TYPE_DATASET)) {
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "'%s' is no longer the same snapshot used in "
                            "the initial send"), toname);
                } else {
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "'%s' used in the initial send no longer exists"),
                            toname);
                }
                return (zfs_error(hdl, EZFS_BADPATH, errbuf));
        }
        zhp = zfs_open(hdl, name, ZFS_TYPE_DATASET);
        if (zhp == NULL) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "unable to access '%s'"), name);
                return (zfs_error(hdl, EZFS_BADPATH, errbuf));
        }

        if (fromguid != 0) {
                if (guid_to_name(hdl, toname, fromguid, B_TRUE, name) != 0) {
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "incremental source %#llx no longer exists"),
                            (longlong_t)fromguid);
                        return (zfs_error(hdl, EZFS_BADPATH, errbuf));
                }
                fromname = name;
        }

        if (flags->verbose) {
                uint64_t size = 0;
                error = lzc_send_space(zhp->zfs_name, fromname,
                    lzc_flags, &size);
                if (error == 0)
                        size = MAX(0, (int64_t)(size - bytes));
                send_print_verbose(stderr, zhp->zfs_name, fromname,
                    size, flags->parsable);
        }

        if (!flags->dryrun) {
                progress_arg_t pa = { 0 };
                pthread_t tid;
                /*
                 * If progress reporting is requested, spawn a new thread to
                 * poll ZFS_IOC_SEND_PROGRESS at a regular interval.
                 */
                if (flags->progress) {
                        pa.pa_zhp = zhp;
                        pa.pa_fd = outfd;
                        pa.pa_parsable = flags->parsable;

                        error = pthread_create(&tid, NULL,
                            send_progress_thread, &pa);
                        if (error != 0) {
                                zfs_close(zhp);
                                return (error);
                        }
                }

                error = lzc_send_resume(zhp->zfs_name, fromname, outfd,
                    lzc_flags, resumeobj, resumeoff);

                if (flags->progress) {
                        (void) pthread_cancel(tid);
                        (void) pthread_join(tid, NULL);
                }

                char errbuf[1024];
                (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
                    "warning: cannot send '%s'"), zhp->zfs_name);

                zfs_close(zhp);

                switch (error) {
                case 0:
                        return (0);
                case EXDEV:
                case ENOENT:
                case EDQUOT:
                case EFBIG:
                case EIO:
                case ENOLINK:
                case ENOSPC:
                case ENOSTR:
                case ENXIO:
                case EPIPE:
                case ERANGE:
                case EFAULT:
                case EROFS:
                        zfs_error_aux(hdl, strerror(errno));
                        return (zfs_error(hdl, EZFS_BADBACKUP, errbuf));

                default:
                        return (zfs_standard_error(hdl, errno, errbuf));
                }
        }


        zfs_close(zhp);

        return (error);
}

/*
 * Generate a send stream for the dataset identified by the argument zhp.
 *
 * The content of the send stream is the snapshot identified by
 * 'tosnap'.  Incremental streams are requested in two ways:
 *     - from the snapshot identified by "fromsnap" (if non-null) or
 *     - from the origin of the dataset identified by zhp, which must
 *       be a clone.  In this case, "fromsnap" is null and "fromorigin"
 *       is TRUE.
 *
 * The send stream is recursive (i.e. dumps a hierarchy of snapshots) and
 * uses a special header (with a hdrtype field of DMU_COMPOUNDSTREAM)
 * if "replicate" is set.  If "doall" is set, dump all the intermediate
 * snapshots. The DMU_COMPOUNDSTREAM header is used in the "doall"
 * case too. If "props" is set, send properties.
 */
int
zfs_send(zfs_handle_t *zhp, const char *fromsnap, const char *tosnap,
    sendflags_t *flags, int outfd, snapfilter_cb_t filter_func,
    void *cb_arg, nvlist_t **debugnvp)
{
        char errbuf[1024];
        send_dump_data_t sdd = { 0 };
        int err = 0;
        nvlist_t *fss = NULL;
        avl_tree_t *fsavl = NULL;
        static uint64_t holdseq;
        int spa_version;
        pthread_t tid = 0;
        int pipefd[2];
        dedup_arg_t dda = { 0 };
        int featureflags = 0;
        FILE *fout;

        (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
            "cannot send '%s'"), zhp->zfs_name);

        if (fromsnap && fromsnap[0] == '\0') {
                zfs_error_aux(zhp->zfs_hdl, dgettext(TEXT_DOMAIN,
                    "zero-length incremental source"));
                return (zfs_error(zhp->zfs_hdl, EZFS_NOENT, errbuf));
        }

        if (zhp->zfs_type == ZFS_TYPE_FILESYSTEM) {
                uint64_t version;
                version = zfs_prop_get_int(zhp, ZFS_PROP_VERSION);
                if (version >= ZPL_VERSION_SA) {
                        featureflags |= DMU_BACKUP_FEATURE_SA_SPILL;
                }
        }

        if (flags->dedup && !flags->dryrun) {
                featureflags |= (DMU_BACKUP_FEATURE_DEDUP |
                    DMU_BACKUP_FEATURE_DEDUPPROPS);
                if ((err = socketpair(AF_UNIX, SOCK_STREAM, 0, pipefd))) {
                        zfs_error_aux(zhp->zfs_hdl, strerror(errno));
                        return (zfs_error(zhp->zfs_hdl, EZFS_PIPEFAILED,
                            errbuf));
                }
                dda.outputfd = outfd;
                dda.inputfd = pipefd[1];
                dda.dedup_hdl = zhp->zfs_hdl;
                if ((err = pthread_create(&tid, NULL, cksummer, &dda))) {
                        (void) close(pipefd[0]);
                        (void) close(pipefd[1]);
                        zfs_error_aux(zhp->zfs_hdl, strerror(errno));
                        return (zfs_error(zhp->zfs_hdl,
                            EZFS_THREADCREATEFAILED, errbuf));
                }
        }

        if (flags->replicate || flags->doall || flags->props) {
                dmu_replay_record_t drr = { 0 };
                char *packbuf = NULL;
                size_t buflen = 0;
                zio_cksum_t zc;

                ZIO_SET_CHECKSUM(&zc, 0, 0, 0, 0);

                if (flags->replicate || flags->props) {
                        nvlist_t *hdrnv;

                        VERIFY(0 == nvlist_alloc(&hdrnv, NV_UNIQUE_NAME, 0));
                        if (fromsnap) {
                                VERIFY(0 == nvlist_add_string(hdrnv,
                                    "fromsnap", fromsnap));
                        }
                        VERIFY(0 == nvlist_add_string(hdrnv, "tosnap", tosnap));
                        if (!flags->replicate) {
                                VERIFY(0 == nvlist_add_boolean(hdrnv,
                                    "not_recursive"));
                        }

                        err = gather_nvlist(zhp->zfs_hdl, zhp->zfs_name,
                            fromsnap, tosnap, flags->replicate, flags->verbose,
                            &fss, &fsavl);
                        if (err)
                                goto err_out;
                        VERIFY(0 == nvlist_add_nvlist(hdrnv, "fss", fss));
                        err = nvlist_pack(hdrnv, &packbuf, &buflen,
                            NV_ENCODE_XDR, 0);
                        if (debugnvp)
                                *debugnvp = hdrnv;
                        else
                                nvlist_free(hdrnv);
                        if (err)
                                goto stderr_out;
                }

                if (!flags->dryrun) {
                        /* write first begin record */
                        drr.drr_type = DRR_BEGIN;
                        drr.drr_u.drr_begin.drr_magic = DMU_BACKUP_MAGIC;
                        DMU_SET_STREAM_HDRTYPE(drr.drr_u.drr_begin.
                            drr_versioninfo, DMU_COMPOUNDSTREAM);
                        DMU_SET_FEATUREFLAGS(drr.drr_u.drr_begin.
                            drr_versioninfo, featureflags);
                        (void) snprintf(drr.drr_u.drr_begin.drr_toname,
                            sizeof (drr.drr_u.drr_begin.drr_toname),
                            "%s@%s", zhp->zfs_name, tosnap);
                        drr.drr_payloadlen = buflen;

                        err = dump_record(&drr, packbuf, buflen, &zc, outfd);
                        free(packbuf);
                        if (err != 0)
                                goto stderr_out;

                        /* write end record */
                        bzero(&drr, sizeof (drr));
                        drr.drr_type = DRR_END;
                        drr.drr_u.drr_end.drr_checksum = zc;
                        err = write(outfd, &drr, sizeof (drr));
                        if (err == -1) {
                                err = errno;
                                goto stderr_out;
                        }

                        err = 0;
                }
        }

        /* dump each stream */
        sdd.fromsnap = fromsnap;
        sdd.tosnap = tosnap;
        if (tid != 0)
                sdd.outfd = pipefd[0];
        else
                sdd.outfd = outfd;
        sdd.replicate = flags->replicate;
        sdd.doall = flags->doall;
        sdd.fromorigin = flags->fromorigin;
        sdd.fss = fss;
        sdd.fsavl = fsavl;
        sdd.verbose = flags->verbose;
        sdd.parsable = flags->parsable;
        sdd.progress = flags->progress;
        sdd.dryrun = flags->dryrun;
        sdd.large_block = flags->largeblock;
        sdd.embed_data = flags->embed_data;
        sdd.compress = flags->compress;
        sdd.filter_cb = filter_func;
        sdd.filter_cb_arg = cb_arg;
        if (debugnvp)
                sdd.debugnv = *debugnvp;
        if (sdd.verbose && sdd.dryrun)
                sdd.std_out = B_TRUE;
        fout = sdd.std_out ? stdout : stderr;

        /*
         * Some flags require that we place user holds on the datasets that are
         * being sent so they don't get destroyed during the send. We can skip
         * this step if the pool is imported read-only since the datasets cannot
         * be destroyed.
         */
        if (!flags->dryrun && !zpool_get_prop_int(zfs_get_pool_handle(zhp),
            ZPOOL_PROP_READONLY, NULL) &&
            zfs_spa_version(zhp, &spa_version) == 0 &&
            spa_version >= SPA_VERSION_USERREFS &&
            (flags->doall || flags->replicate)) {
                ++holdseq;
                (void) snprintf(sdd.holdtag, sizeof (sdd.holdtag),
                    ".send-%d-%llu", getpid(), (u_longlong_t)holdseq);
                sdd.cleanup_fd = open(ZFS_DEV, O_RDWR);
                if (sdd.cleanup_fd < 0) {
                        err = errno;
                        goto stderr_out;
                }
                sdd.snapholds = fnvlist_alloc();
        } else {
                sdd.cleanup_fd = -1;
                sdd.snapholds = NULL;
        }
        if (flags->verbose || sdd.snapholds != NULL) {
                /*
                 * Do a verbose no-op dry run to get all the verbose output
                 * or to gather snapshot hold's before generating any data,
                 * then do a non-verbose real run to generate the streams.
                 */
                sdd.dryrun = B_TRUE;
                err = dump_filesystems(zhp, &sdd);

                if (err != 0)
                        goto stderr_out;

                if (flags->verbose) {
                        if (flags->parsable) {
                                (void) fprintf(fout, "size\t%llu\n",
                                    (longlong_t)sdd.size);
                        } else {
                                char buf[16];
                                zfs_nicenum(sdd.size, buf, sizeof (buf));
                                (void) fprintf(fout, dgettext(TEXT_DOMAIN,
                                    "total estimated size is %s\n"), buf);
                        }
                }

                /* Ensure no snaps found is treated as an error. */
                if (!sdd.seento) {
                        err = ENOENT;
                        goto err_out;
                }

                /* Skip the second run if dryrun was requested. */
                if (flags->dryrun)
                        goto err_out;

                if (sdd.snapholds != NULL) {
                        err = zfs_hold_nvl(zhp, sdd.cleanup_fd, sdd.snapholds);
                        if (err != 0)
                                goto stderr_out;

                        fnvlist_free(sdd.snapholds);
                        sdd.snapholds = NULL;
                }

                sdd.dryrun = B_FALSE;
                sdd.verbose = B_FALSE;
        }

        err = dump_filesystems(zhp, &sdd);
        fsavl_destroy(fsavl);
        nvlist_free(fss);

        /* Ensure no snaps found is treated as an error. */
        if (err == 0 && !sdd.seento)
                err = ENOENT;

        if (tid != 0) {
                if (err != 0)
                        (void) pthread_cancel(tid);
                (void) close(pipefd[0]);
                (void) pthread_join(tid, NULL);
        }

        if (sdd.cleanup_fd != -1) {
                VERIFY(0 == close(sdd.cleanup_fd));
                sdd.cleanup_fd = -1;
        }

        if (!flags->dryrun && (flags->replicate || flags->doall ||
            flags->props)) {
                /*
                 * write final end record.  NB: want to do this even if
                 * there was some error, because it might not be totally
                 * failed.
                 */
                dmu_replay_record_t drr = { 0 };
                drr.drr_type = DRR_END;
                if (write(outfd, &drr, sizeof (drr)) == -1) {
                        return (zfs_standard_error(zhp->zfs_hdl,
                            errno, errbuf));
                }
        }

        return (err || sdd.err);

stderr_out:
        err = zfs_standard_error(zhp->zfs_hdl, err, errbuf);
err_out:
        fsavl_destroy(fsavl);
        nvlist_free(fss);
        fnvlist_free(sdd.snapholds);

        if (sdd.cleanup_fd != -1)
                VERIFY(0 == close(sdd.cleanup_fd));
        if (tid != 0) {
                (void) pthread_cancel(tid);
                (void) close(pipefd[0]);
                (void) pthread_join(tid, NULL);
        }
        return (err);
}

int
zfs_send_one(zfs_handle_t *zhp, const char *from, int fd,
    enum lzc_send_flags flags)
{
        int err;
        libzfs_handle_t *hdl = zhp->zfs_hdl;

        char errbuf[1024];
        (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
            "warning: cannot send '%s'"), zhp->zfs_name);

        err = lzc_send(zhp->zfs_name, from, fd, flags);
        if (err != 0) {
                switch (errno) {
                case EXDEV:
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "not an earlier snapshot from the same fs"));
                        return (zfs_error(hdl, EZFS_CROSSTARGET, errbuf));

                case ENOENT:
                case ESRCH:
                        if (lzc_exists(zhp->zfs_name)) {
                                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                                    "incremental source (%s) does not exist"),
                                    from);
                        }
                        return (zfs_error(hdl, EZFS_NOENT, errbuf));

                case EBUSY:
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "target is busy; if a filesystem, "
                            "it must not be mounted"));
                        return (zfs_error(hdl, EZFS_BUSY, errbuf));

                case EDQUOT:
                case EFBIG:
                case EIO:
                case ENOLINK:
                case ENOSPC:
                case ENOSTR:
                case ENXIO:
                case EPIPE:
                case ERANGE:
                case EFAULT:
                case EROFS:
                        zfs_error_aux(hdl, strerror(errno));
                        return (zfs_error(hdl, EZFS_BADBACKUP, errbuf));

                default:
                        return (zfs_standard_error(hdl, errno, errbuf));
                }
        }
        return (err != 0);
}

/*
 * Routines specific to "zfs recv"
 */

static int
recv_read(libzfs_handle_t *hdl, int fd, void *buf, int ilen,
    boolean_t byteswap, zio_cksum_t *zc)
{
        char *cp = buf;
        int rv;
        int len = ilen;

        assert(ilen <= SPA_MAXBLOCKSIZE);

        do {
                rv = read(fd, cp, len);
                cp += rv;
                len -= rv;
        } while (rv > 0);

        if (rv < 0 || len != 0) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "failed to read from stream"));
                return (zfs_error(hdl, EZFS_BADSTREAM, dgettext(TEXT_DOMAIN,
                    "cannot receive")));
        }

        if (zc) {
                if (byteswap)
                        fletcher_4_incremental_byteswap(buf, ilen, zc);
                else
                        fletcher_4_incremental_native(buf, ilen, zc);
        }
        return (0);
}

static int
recv_read_nvlist(libzfs_handle_t *hdl, int fd, int len, nvlist_t **nvp,
    boolean_t byteswap, zio_cksum_t *zc)
{
        char *buf;
        int err;

        buf = zfs_alloc(hdl, len);
        if (buf == NULL)
                return (ENOMEM);

        err = recv_read(hdl, fd, buf, len, byteswap, zc);
        if (err != 0) {
                free(buf);
                return (err);
        }

        err = nvlist_unpack(buf, len, nvp, 0);
        free(buf);
        if (err != 0) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "invalid "
                    "stream (malformed nvlist)"));
                return (EINVAL);
        }
        return (0);
}

static int
recv_rename(libzfs_handle_t *hdl, const char *name, const char *tryname,
    int baselen, char *newname, recvflags_t *flags)
{
        static int seq;
        zfs_cmd_t zc = {"\0"};
        int err;
        prop_changelist_t *clp;
        zfs_handle_t *zhp;

        zhp = zfs_open(hdl, name, ZFS_TYPE_DATASET);
        if (zhp == NULL)
                return (-1);
        clp = changelist_gather(zhp, ZFS_PROP_NAME, 0,
            flags->force ? MS_FORCE : 0);
        zfs_close(zhp);
        if (clp == NULL)
                return (-1);
        err = changelist_prefix(clp);
        if (err)
                return (err);

        zc.zc_objset_type = DMU_OST_ZFS;
        (void) strlcpy(zc.zc_name, name, sizeof (zc.zc_name));

        if (tryname) {
                (void) strcpy(newname, tryname);

                (void) strlcpy(zc.zc_value, tryname, sizeof (zc.zc_value));

                if (flags->verbose) {
                        (void) printf("attempting rename %s to %s\n",
                            zc.zc_name, zc.zc_value);
                }
                err = ioctl(hdl->libzfs_fd, ZFS_IOC_RENAME, &zc);
                if (err == 0)
                        changelist_rename(clp, name, tryname);
        } else {
                err = ENOENT;
        }

        if (err != 0 && strncmp(name + baselen, "recv-", 5) != 0) {
                seq++;

                (void) snprintf(newname, ZFS_MAX_DATASET_NAME_LEN,
                    "%.*srecv-%u-%u", baselen, name, getpid(), seq);
                (void) strlcpy(zc.zc_value, newname, sizeof (zc.zc_value));

                if (flags->verbose) {
                        (void) printf("failed - trying rename %s to %s\n",
                            zc.zc_name, zc.zc_value);
                }
                err = ioctl(hdl->libzfs_fd, ZFS_IOC_RENAME, &zc);
                if (err == 0)
                        changelist_rename(clp, name, newname);
                if (err && flags->verbose) {
                        (void) printf("failed (%u) - "
                            "will try again on next pass\n", errno);
                }
                err = EAGAIN;
        } else if (flags->verbose) {
                if (err == 0)
                        (void) printf("success\n");
                else
                        (void) printf("failed (%u)\n", errno);
        }

        (void) changelist_postfix(clp);
        changelist_free(clp);

        return (err);
}

static int
recv_destroy(libzfs_handle_t *hdl, const char *name, int baselen,
    char *newname, recvflags_t *flags)
{
        zfs_cmd_t zc = {"\0"};
        int err = 0;
        prop_changelist_t *clp;
        zfs_handle_t *zhp;
        boolean_t defer = B_FALSE;
        int spa_version;

        zhp = zfs_open(hdl, name, ZFS_TYPE_DATASET);
        if (zhp == NULL)
                return (-1);
        clp = changelist_gather(zhp, ZFS_PROP_NAME, 0,
            flags->force ? MS_FORCE : 0);
        if (zfs_get_type(zhp) == ZFS_TYPE_SNAPSHOT &&
            zfs_spa_version(zhp, &spa_version) == 0 &&
            spa_version >= SPA_VERSION_USERREFS)
                defer = B_TRUE;
        zfs_close(zhp);
        if (clp == NULL)
                return (-1);
        err = changelist_prefix(clp);
        if (err)
                return (err);

        zc.zc_objset_type = DMU_OST_ZFS;
        zc.zc_defer_destroy = defer;
        (void) strlcpy(zc.zc_name, name, sizeof (zc.zc_name));

        if (flags->verbose)
                (void) printf("attempting destroy %s\n", zc.zc_name);
        err = ioctl(hdl->libzfs_fd, ZFS_IOC_DESTROY, &zc);
        if (err == 0) {
                if (flags->verbose)
                        (void) printf("success\n");
                changelist_remove(clp, zc.zc_name);
        }

        (void) changelist_postfix(clp);
        changelist_free(clp);

        /*
         * Deferred destroy might destroy the snapshot or only mark it to be
         * destroyed later, and it returns success in either case.
         */
        if (err != 0 || (defer && zfs_dataset_exists(hdl, name,
            ZFS_TYPE_SNAPSHOT))) {
                err = recv_rename(hdl, name, NULL, baselen, newname, flags);
        }

        return (err);
}

typedef struct guid_to_name_data {
        uint64_t guid;
        boolean_t bookmark_ok;
        char *name;
        char *skip;
} guid_to_name_data_t;

static int
guid_to_name_cb(zfs_handle_t *zhp, void *arg)
{
        guid_to_name_data_t *gtnd = arg;
        const char *slash;
        int err;

        if (gtnd->skip != NULL &&
            (slash = strrchr(zhp->zfs_name, '/')) != NULL &&
            strcmp(slash + 1, gtnd->skip) == 0) {
                zfs_close(zhp);
                return (0);
        }

        if (zfs_prop_get_int(zhp, ZFS_PROP_GUID) == gtnd->guid) {
                (void) strcpy(gtnd->name, zhp->zfs_name);
                zfs_close(zhp);
                return (EEXIST);
        }

        err = zfs_iter_children(zhp, guid_to_name_cb, gtnd);
        if (err != EEXIST && gtnd->bookmark_ok)
                err = zfs_iter_bookmarks(zhp, guid_to_name_cb, gtnd);
        zfs_close(zhp);
        return (err);
}

/*
 * Attempt to find the local dataset associated with this guid.  In the case of
 * multiple matches, we attempt to find the "best" match by searching
 * progressively larger portions of the hierarchy.  This allows one to send a
 * tree of datasets individually and guarantee that we will find the source
 * guid within that hierarchy, even if there are multiple matches elsewhere.
 */
static int
guid_to_name(libzfs_handle_t *hdl, const char *parent, uint64_t guid,
    boolean_t bookmark_ok, char *name)
{
        char pname[ZFS_MAX_DATASET_NAME_LEN];
        guid_to_name_data_t gtnd;

        gtnd.guid = guid;
        gtnd.bookmark_ok = bookmark_ok;
        gtnd.name = name;
        gtnd.skip = NULL;

        /*
         * Search progressively larger portions of the hierarchy, starting
         * with the filesystem specified by 'parent'.  This will
         * select the "most local" version of the origin snapshot in the case
         * that there are multiple matching snapshots in the system.
         */
        (void) strlcpy(pname, parent, sizeof (pname));
        char *cp = strrchr(pname, '@');
        if (cp == NULL)
                cp = strchr(pname, '\0');
        for (; cp != NULL; cp = strrchr(pname, '/')) {
                /* Chop off the last component and open the parent */
                *cp = '\0';
                zfs_handle_t *zhp = make_dataset_handle(hdl, pname);

                if (zhp == NULL)
                        continue;
                int err = guid_to_name_cb(zfs_handle_dup(zhp), &gtnd);
                if (err != EEXIST)
                        err = zfs_iter_children(zhp, guid_to_name_cb, &gtnd);
                if (err != EEXIST && bookmark_ok)
                        err = zfs_iter_bookmarks(zhp, guid_to_name_cb, &gtnd);
                zfs_close(zhp);
                if (err == EEXIST)
                        return (0);

                /*
                 * Remember the last portion of the dataset so we skip it next
                 * time through (as we've already searched that portion of the
                 * hierarchy).
                 */
                gtnd.skip = strrchr(pname, '/') + 1;
        }

        return (ENOENT);
}

/*
 * Return +1 if guid1 is before guid2, 0 if they are the same, and -1 if
 * guid1 is after guid2.
 */
static int
created_before(libzfs_handle_t *hdl, avl_tree_t *avl,
    uint64_t guid1, uint64_t guid2)
{
        nvlist_t *nvfs;
        char *fsname = NULL, *snapname = NULL;
        char buf[ZFS_MAX_DATASET_NAME_LEN];
        int rv;
        zfs_handle_t *guid1hdl, *guid2hdl;
        uint64_t create1, create2;

        if (guid2 == 0)
                return (0);
        if (guid1 == 0)
                return (1);

        nvfs = fsavl_find(avl, guid1, &snapname);
        VERIFY(0 == nvlist_lookup_string(nvfs, "name", &fsname));
        (void) snprintf(buf, sizeof (buf), "%s@%s", fsname, snapname);
        guid1hdl = zfs_open(hdl, buf, ZFS_TYPE_SNAPSHOT);
        if (guid1hdl == NULL)
                return (-1);

        nvfs = fsavl_find(avl, guid2, &snapname);
        VERIFY(0 == nvlist_lookup_string(nvfs, "name", &fsname));
        (void) snprintf(buf, sizeof (buf), "%s@%s", fsname, snapname);
        guid2hdl = zfs_open(hdl, buf, ZFS_TYPE_SNAPSHOT);
        if (guid2hdl == NULL) {
                zfs_close(guid1hdl);
                return (-1);
        }

        create1 = zfs_prop_get_int(guid1hdl, ZFS_PROP_CREATETXG);
        create2 = zfs_prop_get_int(guid2hdl, ZFS_PROP_CREATETXG);

        if (create1 < create2)
                rv = -1;
        else if (create1 > create2)
                rv = +1;
        else
                rv = 0;

        zfs_close(guid1hdl);
        zfs_close(guid2hdl);

        return (rv);
}

static int
recv_incremental_replication(libzfs_handle_t *hdl, const char *tofs,
    recvflags_t *flags, nvlist_t *stream_nv, avl_tree_t *stream_avl,
    nvlist_t *renamed)
{
        nvlist_t *local_nv, *deleted = NULL;
        avl_tree_t *local_avl;
        nvpair_t *fselem, *nextfselem;
        char *fromsnap;
        char newname[ZFS_MAX_DATASET_NAME_LEN];
        char guidname[32];
        int error;
        boolean_t needagain, progress, recursive;
        char *s1, *s2;

        VERIFY(0 == nvlist_lookup_string(stream_nv, "fromsnap", &fromsnap));

        recursive = (nvlist_lookup_boolean(stream_nv, "not_recursive") ==
            ENOENT);

        if (flags->dryrun)
                return (0);

again:
        needagain = progress = B_FALSE;

        VERIFY(0 == nvlist_alloc(&deleted, NV_UNIQUE_NAME, 0));

        if ((error = gather_nvlist(hdl, tofs, fromsnap, NULL,
            recursive, B_FALSE, &local_nv, &local_avl)) != 0)
                return (error);

        /*
         * Process deletes and renames
         */
        for (fselem = nvlist_next_nvpair(local_nv, NULL);
            fselem; fselem = nextfselem) {
                nvlist_t *nvfs, *snaps;
                nvlist_t *stream_nvfs = NULL;
                nvpair_t *snapelem, *nextsnapelem;
                uint64_t fromguid = 0;
                uint64_t originguid = 0;
                uint64_t stream_originguid = 0;
                uint64_t parent_fromsnap_guid, stream_parent_fromsnap_guid;
                char *fsname, *stream_fsname;

                nextfselem = nvlist_next_nvpair(local_nv, fselem);

                VERIFY(0 == nvpair_value_nvlist(fselem, &nvfs));
                VERIFY(0 == nvlist_lookup_nvlist(nvfs, "snaps", &snaps));
                VERIFY(0 == nvlist_lookup_string(nvfs, "name", &fsname));
                VERIFY(0 == nvlist_lookup_uint64(nvfs, "parentfromsnap",
                    &parent_fromsnap_guid));
                (void) nvlist_lookup_uint64(nvfs, "origin", &originguid);

                /*
                 * First find the stream's fs, so we can check for
                 * a different origin (due to "zfs promote")
                 */
                for (snapelem = nvlist_next_nvpair(snaps, NULL);
                    snapelem; snapelem = nvlist_next_nvpair(snaps, snapelem)) {
                        uint64_t thisguid;

                        VERIFY(0 == nvpair_value_uint64(snapelem, &thisguid));
                        stream_nvfs = fsavl_find(stream_avl, thisguid, NULL);

                        if (stream_nvfs != NULL)
                                break;
                }

                /* check for promote */
                (void) nvlist_lookup_uint64(stream_nvfs, "origin",
                    &stream_originguid);
                if (stream_nvfs && originguid != stream_originguid) {
                        switch (created_before(hdl, local_avl,
                            stream_originguid, originguid)) {
                        case 1: {
                                /* promote it! */
                                zfs_cmd_t zc = {"\0"};
                                nvlist_t *origin_nvfs;
                                char *origin_fsname;

                                if (flags->verbose)
                                        (void) printf("promoting %s\n", fsname);

                                origin_nvfs = fsavl_find(local_avl, originguid,
                                    NULL);
                                VERIFY(0 == nvlist_lookup_string(origin_nvfs,
                                    "name", &origin_fsname));
                                (void) strlcpy(zc.zc_value, origin_fsname,
                                    sizeof (zc.zc_value));
                                (void) strlcpy(zc.zc_name, fsname,
                                    sizeof (zc.zc_name));
                                error = zfs_ioctl(hdl, ZFS_IOC_PROMOTE, &zc);
                                if (error == 0)
                                        progress = B_TRUE;
                                break;
                        }
                        default:
                                break;
                        case -1:
                                fsavl_destroy(local_avl);
                                nvlist_free(local_nv);
                                return (-1);
                        }
                        /*
                         * We had/have the wrong origin, therefore our
                         * list of snapshots is wrong.  Need to handle
                         * them on the next pass.
                         */
                        needagain = B_TRUE;
                        continue;
                }

                for (snapelem = nvlist_next_nvpair(snaps, NULL);
                    snapelem; snapelem = nextsnapelem) {
                        uint64_t thisguid;
                        char *stream_snapname;
                        nvlist_t *found, *props;

                        nextsnapelem = nvlist_next_nvpair(snaps, snapelem);

                        VERIFY(0 == nvpair_value_uint64(snapelem, &thisguid));
                        found = fsavl_find(stream_avl, thisguid,
                            &stream_snapname);

                        /* check for delete */
                        if (found == NULL) {
                                char name[ZFS_MAX_DATASET_NAME_LEN];

                                if (!flags->force)
                                        continue;

                                (void) snprintf(name, sizeof (name), "%s@%s",
                                    fsname, nvpair_name(snapelem));

                                error = recv_destroy(hdl, name,
                                    strlen(fsname)+1, newname, flags);
                                if (error)
                                        needagain = B_TRUE;
                                else
                                        progress = B_TRUE;
                                sprintf(guidname, "%llu",
                                    (u_longlong_t)thisguid);
                                nvlist_add_boolean(deleted, guidname);
                                continue;
                        }

                        stream_nvfs = found;

                        if (0 == nvlist_lookup_nvlist(stream_nvfs, "snapprops",
                            &props) && 0 == nvlist_lookup_nvlist(props,
                            stream_snapname, &props)) {
                                zfs_cmd_t zc = {"\0"};

                                zc.zc_cookie = B_TRUE; /* received */
                                (void) snprintf(zc.zc_name, sizeof (zc.zc_name),
                                    "%s@%s", fsname, nvpair_name(snapelem));
                                if (zcmd_write_src_nvlist(hdl, &zc,
                                    props) == 0) {
                                        (void) zfs_ioctl(hdl,
                                            ZFS_IOC_SET_PROP, &zc);
                                        zcmd_free_nvlists(&zc);
                                }
                        }

                        /* check for different snapname */
                        if (strcmp(nvpair_name(snapelem),
                            stream_snapname) != 0) {
                                char name[ZFS_MAX_DATASET_NAME_LEN];
                                char tryname[ZFS_MAX_DATASET_NAME_LEN];

                                (void) snprintf(name, sizeof (name), "%s@%s",
                                    fsname, nvpair_name(snapelem));
                                (void) snprintf(tryname, sizeof (name), "%s@%s",
                                    fsname, stream_snapname);

                                error = recv_rename(hdl, name, tryname,
                                    strlen(fsname)+1, newname, flags);
                                if (error)
                                        needagain = B_TRUE;
                                else
                                        progress = B_TRUE;
                        }

                        if (strcmp(stream_snapname, fromsnap) == 0)
                                fromguid = thisguid;
                }

                /* check for delete */
                if (stream_nvfs == NULL) {
                        if (!flags->force)
                                continue;

                        error = recv_destroy(hdl, fsname, strlen(tofs)+1,
                            newname, flags);
                        if (error)
                                needagain = B_TRUE;
                        else
                                progress = B_TRUE;
                        sprintf(guidname, "%llu",
                            (u_longlong_t)parent_fromsnap_guid);
                        nvlist_add_boolean(deleted, guidname);
                        continue;
                }

                if (fromguid == 0) {
                        if (flags->verbose) {
                                (void) printf("local fs %s does not have "
                                    "fromsnap (%s in stream); must have "
                                    "been deleted locally; ignoring\n",
                                    fsname, fromsnap);
                        }
                        continue;
                }

                VERIFY(0 == nvlist_lookup_string(stream_nvfs,
                    "name", &stream_fsname));
                VERIFY(0 == nvlist_lookup_uint64(stream_nvfs,
                    "parentfromsnap", &stream_parent_fromsnap_guid));

                s1 = strrchr(fsname, '/');
                s2 = strrchr(stream_fsname, '/');

                /*
                 * Check if we're going to rename based on parent guid change
                 * and the current parent guid was also deleted. If it was then
                 * rename will fail and is likely unneeded, so avoid this and
                 * force an early retry to determine the new
                 * parent_fromsnap_guid.
                 */
                if (stream_parent_fromsnap_guid != 0 &&
                    parent_fromsnap_guid != 0 &&
                    stream_parent_fromsnap_guid != parent_fromsnap_guid) {
                        sprintf(guidname, "%llu",
                            (u_longlong_t)parent_fromsnap_guid);
                        if (nvlist_exists(deleted, guidname)) {
                                progress = B_TRUE;
                                needagain = B_TRUE;
                                goto doagain;
                        }
                }

                /*
                 * Check for rename. If the exact receive path is specified, it
                 * does not count as a rename, but we still need to check the
                 * datasets beneath it.
                 */
                if ((stream_parent_fromsnap_guid != 0 &&
                    parent_fromsnap_guid != 0 &&
                    stream_parent_fromsnap_guid != parent_fromsnap_guid) ||
                    ((flags->isprefix || strcmp(tofs, fsname) != 0) &&
                    (s1 != NULL) && (s2 != NULL) && strcmp(s1, s2) != 0)) {
                        nvlist_t *parent;
                        char tryname[ZFS_MAX_DATASET_NAME_LEN];

                        parent = fsavl_find(local_avl,
                            stream_parent_fromsnap_guid, NULL);
                        /*
                         * NB: parent might not be found if we used the
                         * tosnap for stream_parent_fromsnap_guid,
                         * because the parent is a newly-created fs;
                         * we'll be able to rename it after we recv the
                         * new fs.
                         */
                        if (parent != NULL) {
                                char *pname;

                                VERIFY(0 == nvlist_lookup_string(parent, "name",
                                    &pname));
                                (void) snprintf(tryname, sizeof (tryname),
                                    "%s%s", pname, strrchr(stream_fsname, '/'));
                        } else {
                                tryname[0] = '\0';
                                if (flags->verbose) {
                                        (void) printf("local fs %s new parent "
                                            "not found\n", fsname);
                                }
                        }

                        newname[0] = '\0';

                        error = recv_rename(hdl, fsname, tryname,
                            strlen(tofs)+1, newname, flags);

                        if (renamed != NULL && newname[0] != '\0') {
                                VERIFY(0 == nvlist_add_boolean(renamed,
                                    newname));
                        }

                        if (error)
                                needagain = B_TRUE;
                        else
                                progress = B_TRUE;
                }
        }

doagain:
        fsavl_destroy(local_avl);
        nvlist_free(local_nv);
        nvlist_free(deleted);

        if (needagain && progress) {
                /* do another pass to fix up temporary names */
                if (flags->verbose)
                        (void) printf("another pass:\n");
                goto again;
        }

        return (needagain);
}

static int
zfs_receive_package(libzfs_handle_t *hdl, int fd, const char *destname,
    recvflags_t *flags, dmu_replay_record_t *drr, zio_cksum_t *zc,
    char **top_zfs, int cleanup_fd, uint64_t *action_handlep)
{
        nvlist_t *stream_nv = NULL;
        avl_tree_t *stream_avl = NULL;
        char *fromsnap = NULL;
        char *sendsnap = NULL;
        char *cp;
        char tofs[ZFS_MAX_DATASET_NAME_LEN];
        char sendfs[ZFS_MAX_DATASET_NAME_LEN];
        char errbuf[1024];
        dmu_replay_record_t drre;
        int error;
        boolean_t anyerr = B_FALSE;
        boolean_t softerr = B_FALSE;
        boolean_t recursive;

        (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
            "cannot receive"));

        assert(drr->drr_type == DRR_BEGIN);
        assert(drr->drr_u.drr_begin.drr_magic == DMU_BACKUP_MAGIC);
        assert(DMU_GET_STREAM_HDRTYPE(drr->drr_u.drr_begin.drr_versioninfo) ==
            DMU_COMPOUNDSTREAM);

        /*
         * Read in the nvlist from the stream.
         */
        if (drr->drr_payloadlen != 0) {
                error = recv_read_nvlist(hdl, fd, drr->drr_payloadlen,
                    &stream_nv, flags->byteswap, zc);
                if (error) {
                        error = zfs_error(hdl, EZFS_BADSTREAM, errbuf);
                        goto out;
                }
        }

        recursive = (nvlist_lookup_boolean(stream_nv, "not_recursive") ==
            ENOENT);

        if (recursive && strchr(destname, '@')) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "cannot specify snapshot name for multi-snapshot stream"));
                error = zfs_error(hdl, EZFS_BADSTREAM, errbuf);
                goto out;
        }

        /*
         * Read in the end record and verify checksum.
         */
        if (0 != (error = recv_read(hdl, fd, &drre, sizeof (drre),
            flags->byteswap, NULL)))
                goto out;
        if (flags->byteswap) {
                drre.drr_type = BSWAP_32(drre.drr_type);
                drre.drr_u.drr_end.drr_checksum.zc_word[0] =
                    BSWAP_64(drre.drr_u.drr_end.drr_checksum.zc_word[0]);
                drre.drr_u.drr_end.drr_checksum.zc_word[1] =
                    BSWAP_64(drre.drr_u.drr_end.drr_checksum.zc_word[1]);
                drre.drr_u.drr_end.drr_checksum.zc_word[2] =
                    BSWAP_64(drre.drr_u.drr_end.drr_checksum.zc_word[2]);
                drre.drr_u.drr_end.drr_checksum.zc_word[3] =
                    BSWAP_64(drre.drr_u.drr_end.drr_checksum.zc_word[3]);
        }
        if (drre.drr_type != DRR_END) {
                error = zfs_error(hdl, EZFS_BADSTREAM, errbuf);
                goto out;
        }
        if (!ZIO_CHECKSUM_EQUAL(drre.drr_u.drr_end.drr_checksum, *zc)) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "incorrect header checksum"));
                error = zfs_error(hdl, EZFS_BADSTREAM, errbuf);
                goto out;
        }

        (void) nvlist_lookup_string(stream_nv, "fromsnap", &fromsnap);

        if (drr->drr_payloadlen != 0) {
                nvlist_t *stream_fss;

                VERIFY(0 == nvlist_lookup_nvlist(stream_nv, "fss",
                    &stream_fss));
                if ((stream_avl = fsavl_create(stream_fss)) == NULL) {
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "couldn't allocate avl tree"));
                        error = zfs_error(hdl, EZFS_NOMEM, errbuf);
                        goto out;
                }

                if (fromsnap != NULL) {
                        nvlist_t *renamed = NULL;
                        nvpair_t *pair = NULL;

                        (void) strlcpy(tofs, destname, sizeof (tofs));
                        if (flags->isprefix) {
                                struct drr_begin *drrb = &drr->drr_u.drr_begin;
                                int i;

                                if (flags->istail) {
                                        cp = strrchr(drrb->drr_toname, '/');
                                        if (cp == NULL) {
                                                (void) strlcat(tofs, "/",
                                                    sizeof (tofs));
                                                i = 0;
                                        } else {
                                                i = (cp - drrb->drr_toname);
                                        }
                                } else {
                                        i = strcspn(drrb->drr_toname, "/@");
                                }
                                /* zfs_receive_one() will create_parents() */
                                (void) strlcat(tofs, &drrb->drr_toname[i],
                                    sizeof (tofs));
                                *strchr(tofs, '@') = '\0';
                        }

                        if (recursive && !flags->dryrun && !flags->nomount) {
                                VERIFY(0 == nvlist_alloc(&renamed,
                                    NV_UNIQUE_NAME, 0));
                        }

                        softerr = recv_incremental_replication(hdl, tofs, flags,
                            stream_nv, stream_avl, renamed);

                        /* Unmount renamed filesystems before receiving. */
                        while ((pair = nvlist_next_nvpair(renamed,
                            pair)) != NULL) {
                                zfs_handle_t *zhp;
                                prop_changelist_t *clp = NULL;

                                zhp = zfs_open(hdl, nvpair_name(pair),
                                    ZFS_TYPE_FILESYSTEM);
                                if (zhp != NULL) {
                                        clp = changelist_gather(zhp,
                                            ZFS_PROP_MOUNTPOINT, 0, 0);
                                        zfs_close(zhp);
                                        if (clp != NULL) {
                                                softerr |=
                                                    changelist_prefix(clp);
                                                changelist_free(clp);
                                        }
                                }
                        }

                        nvlist_free(renamed);
                }
        }

        /*
         * Get the fs specified by the first path in the stream (the top level
         * specified by 'zfs send') and pass it to each invocation of
         * zfs_receive_one().
         */
        (void) strlcpy(sendfs, drr->drr_u.drr_begin.drr_toname,
            sizeof (sendfs));
        if ((cp = strchr(sendfs, '@')) != NULL) {
                *cp = '\0';
                /*
                 * Find the "sendsnap", the final snapshot in a replication
                 * stream.  zfs_receive_one() handles certain errors
                 * differently, depending on if the contained stream is the
                 * last one or not.
                 */
                sendsnap = (cp + 1);
        }

        /* Finally, receive each contained stream */
        do {
                /*
                 * we should figure out if it has a recoverable
                 * error, in which case do a recv_skip() and drive on.
                 * Note, if we fail due to already having this guid,
                 * zfs_receive_one() will take care of it (ie,
                 * recv_skip() and return 0).
                 */
                error = zfs_receive_impl(hdl, destname, NULL, flags, fd,
                    sendfs, stream_nv, stream_avl, top_zfs, cleanup_fd,
                    action_handlep, sendsnap);
                if (error == ENODATA) {
                        error = 0;
                        break;
                }
                anyerr |= error;
        } while (error == 0);

        if (drr->drr_payloadlen != 0 && fromsnap != NULL) {
                /*
                 * Now that we have the fs's they sent us, try the
                 * renames again.
                 */
                softerr = recv_incremental_replication(hdl, tofs, flags,
                    stream_nv, stream_avl, NULL);
        }

out:
        fsavl_destroy(stream_avl);
        nvlist_free(stream_nv);
        if (softerr)
                error = -2;
        if (anyerr)
                error = -1;
        return (error);
}

static void
trunc_prop_errs(int truncated)
{
        ASSERT(truncated != 0);

        if (truncated == 1)
                (void) fprintf(stderr, dgettext(TEXT_DOMAIN,
                    "1 more property could not be set\n"));
        else
                (void) fprintf(stderr, dgettext(TEXT_DOMAIN,
                    "%d more properties could not be set\n"), truncated);
}

static int
recv_skip(libzfs_handle_t *hdl, int fd, boolean_t byteswap)
{
        dmu_replay_record_t *drr;
        void *buf = zfs_alloc(hdl, SPA_MAXBLOCKSIZE);
        char errbuf[1024];

        (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
            "cannot receive:"));

        /* XXX would be great to use lseek if possible... */
        drr = buf;

        while (recv_read(hdl, fd, drr, sizeof (dmu_replay_record_t),
            byteswap, NULL) == 0) {
                if (byteswap)
                        drr->drr_type = BSWAP_32(drr->drr_type);

                switch (drr->drr_type) {
                case DRR_BEGIN:
                        if (drr->drr_payloadlen != 0) {
                                (void) recv_read(hdl, fd, buf,
                                    drr->drr_payloadlen, B_FALSE, NULL);
                        }
                        break;

                case DRR_END:
                        free(buf);
                        return (0);

                case DRR_OBJECT:
                        if (byteswap) {
                                drr->drr_u.drr_object.drr_bonuslen =
                                    BSWAP_32(drr->drr_u.drr_object.
                                    drr_bonuslen);
                        }
                        (void) recv_read(hdl, fd, buf,
                            P2ROUNDUP(drr->drr_u.drr_object.drr_bonuslen, 8),
                            B_FALSE, NULL);
                        break;

                case DRR_WRITE:
                        if (byteswap) {
                                drr->drr_u.drr_write.drr_logical_size =
                                    BSWAP_64(
                                    drr->drr_u.drr_write.drr_logical_size);
                                drr->drr_u.drr_write.drr_compressed_size =
                                    BSWAP_64(
                                    drr->drr_u.drr_write.drr_compressed_size);
                        }
                        uint64_t payload_size =
                            DRR_WRITE_PAYLOAD_SIZE(&drr->drr_u.drr_write);
                        (void) recv_read(hdl, fd, buf,
                            payload_size, B_FALSE, NULL);
                        break;
                case DRR_SPILL:
                        if (byteswap) {
                                drr->drr_u.drr_spill.drr_length =
                                    BSWAP_64(drr->drr_u.drr_spill.drr_length);
                        }
                        (void) recv_read(hdl, fd, buf,
                            drr->drr_u.drr_spill.drr_length, B_FALSE, NULL);
                        break;
                case DRR_WRITE_EMBEDDED:
                        if (byteswap) {
                                drr->drr_u.drr_write_embedded.drr_psize =
                                    BSWAP_32(drr->drr_u.drr_write_embedded.
                                    drr_psize);
                        }
                        (void) recv_read(hdl, fd, buf,
                            P2ROUNDUP(drr->drr_u.drr_write_embedded.drr_psize,
                            8), B_FALSE, NULL);
                        break;
                case DRR_WRITE_BYREF:
                case DRR_FREEOBJECTS:
                case DRR_FREE:
                        break;

                default:
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "invalid record type"));
                        free(buf);
                        return (zfs_error(hdl, EZFS_BADSTREAM, errbuf));
                }
        }

        free(buf);
        return (-1);
}

static void
recv_ecksum_set_aux(libzfs_handle_t *hdl, const char *target_snap,
    boolean_t resumable)
{
        char target_fs[ZFS_MAX_DATASET_NAME_LEN];

        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
            "checksum mismatch or incomplete stream"));

        if (!resumable)
                return;
        (void) strlcpy(target_fs, target_snap, sizeof (target_fs));
        *strchr(target_fs, '@') = '\0';
        zfs_handle_t *zhp = zfs_open(hdl, target_fs,
            ZFS_TYPE_FILESYSTEM | ZFS_TYPE_VOLUME);
        if (zhp == NULL)
                return;

        char token_buf[ZFS_MAXPROPLEN];
        int error = zfs_prop_get(zhp, ZFS_PROP_RECEIVE_RESUME_TOKEN,
            token_buf, sizeof (token_buf),
            NULL, NULL, 0, B_TRUE);
        if (error == 0) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "checksum mismatch or incomplete stream.\n"
                    "Partially received snapshot is saved.\n"
                    "A resuming stream can be generated on the sending "
                    "system by running:\n"
                    "    zfs send -t %s"),
                    token_buf);
        }
        zfs_close(zhp);
}

/*
 * Restores a backup of tosnap from the file descriptor specified by infd.
 */
static int
zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
    const char *originsnap, recvflags_t *flags, dmu_replay_record_t *drr,
    dmu_replay_record_t *drr_noswap, const char *sendfs, nvlist_t *stream_nv,
    avl_tree_t *stream_avl, char **top_zfs, int cleanup_fd,
    uint64_t *action_handlep, const char *finalsnap)
{
        time_t begin_time;
        int ioctl_err, ioctl_errno, err;
        char *cp;
        struct drr_begin *drrb = &drr->drr_u.drr_begin;
        char errbuf[1024];
        const char *chopprefix;
        boolean_t newfs = B_FALSE;
        boolean_t stream_wantsnewfs;
        boolean_t newprops = B_FALSE;
        uint64_t read_bytes = 0;
        uint64_t errflags = 0;
        uint64_t parent_snapguid = 0;
        prop_changelist_t *clp = NULL;
        nvlist_t *snapprops_nvlist = NULL;
        zprop_errflags_t prop_errflags;
        nvlist_t *prop_errors = NULL;
        boolean_t recursive;
        char *snapname = NULL;
        char destsnap[MAXPATHLEN * 2];
        char origin[MAXNAMELEN];
        char name[MAXPATHLEN];
        nvlist_t *props = NULL;

        begin_time = time(NULL);
        bzero(origin, MAXNAMELEN);

        (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
            "cannot receive"));

        recursive = (nvlist_lookup_boolean(stream_nv, "not_recursive") ==
            ENOENT);

        if (stream_avl != NULL) {
                nvlist_t *lookup = NULL;
                nvlist_t *fs = fsavl_find(stream_avl, drrb->drr_toguid,
                    &snapname);

                (void) nvlist_lookup_uint64(fs, "parentfromsnap",
                    &parent_snapguid);
                err = nvlist_lookup_nvlist(fs, "props", &props);
                if (err) {
                        VERIFY(0 == nvlist_alloc(&props, NV_UNIQUE_NAME, 0));
                        newprops = B_TRUE;
                }

                if (flags->canmountoff) {
                        VERIFY(0 == nvlist_add_uint64(props,
                            zfs_prop_to_name(ZFS_PROP_CANMOUNT), 0));
                }
                if (0 == nvlist_lookup_nvlist(fs, "snapprops", &lookup)) {
                        VERIFY(0 == nvlist_lookup_nvlist(lookup,
                            snapname, &snapprops_nvlist));
                }
        }

        cp = NULL;

        /*
         * Determine how much of the snapshot name stored in the stream
         * we are going to tack on to the name they specified on the
         * command line, and how much we are going to chop off.
         *
         * If they specified a snapshot, chop the entire name stored in
         * the stream.
         */
        if (flags->istail) {
                /*
                 * A filesystem was specified with -e. We want to tack on only
                 * the tail of the sent snapshot path.
                 */
                if (strchr(tosnap, '@')) {
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "invalid "
                            "argument - snapshot not allowed with -e"));
                        err = zfs_error(hdl, EZFS_INVALIDNAME, errbuf);
                        goto out;
                }

                chopprefix = strrchr(sendfs, '/');

                if (chopprefix == NULL) {
                        /*
                         * The tail is the poolname, so we need to
                         * prepend a path separator.
                         */
                        int len = strlen(drrb->drr_toname);
                        cp = malloc(len + 2);
                        cp[0] = '/';
                        (void) strcpy(&cp[1], drrb->drr_toname);
                        chopprefix = cp;
                } else {
                        chopprefix = drrb->drr_toname + (chopprefix - sendfs);
                }
        } else if (flags->isprefix) {
                /*
                 * A filesystem was specified with -d. We want to tack on
                 * everything but the first element of the sent snapshot path
                 * (all but the pool name).
                 */
                if (strchr(tosnap, '@')) {
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "invalid "
                            "argument - snapshot not allowed with -d"));
                        err = zfs_error(hdl, EZFS_INVALIDNAME, errbuf);
                        goto out;
                }

                chopprefix = strchr(drrb->drr_toname, '/');
                if (chopprefix == NULL)
                        chopprefix = strchr(drrb->drr_toname, '@');
        } else if (strchr(tosnap, '@') == NULL) {
                /*
                 * If a filesystem was specified without -d or -e, we want to
                 * tack on everything after the fs specified by 'zfs send'.
                 */
                chopprefix = drrb->drr_toname + strlen(sendfs);
        } else {
                /* A snapshot was specified as an exact path (no -d or -e). */
                if (recursive) {
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "cannot specify snapshot name for multi-snapshot "
                            "stream"));
                        err = zfs_error(hdl, EZFS_BADSTREAM, errbuf);
                        goto out;
                }
                chopprefix = drrb->drr_toname + strlen(drrb->drr_toname);
        }

        ASSERT(strstr(drrb->drr_toname, sendfs) == drrb->drr_toname);
        ASSERT(chopprefix > drrb->drr_toname);
        ASSERT(chopprefix <= drrb->drr_toname + strlen(drrb->drr_toname));
        ASSERT(chopprefix[0] == '/' || chopprefix[0] == '@' ||
            chopprefix[0] == '\0');

        /*
         * Determine name of destination snapshot.
         */
        (void) strlcpy(destsnap, tosnap, sizeof (destsnap));
        (void) strlcat(destsnap, chopprefix, sizeof (destsnap));
        free(cp);
        if (!zfs_name_valid(destsnap, ZFS_TYPE_SNAPSHOT)) {
                err = zfs_error(hdl, EZFS_INVALIDNAME, errbuf);
                goto out;
        }

        /*
         * Determine the name of the origin snapshot.
         */
        if (originsnap) {
                (void) strncpy(origin, originsnap, sizeof (origin));
                if (flags->verbose)
                        (void) printf("using provided clone origin %s\n",
                            origin);
        } else if (drrb->drr_flags & DRR_FLAG_CLONE) {
                if (guid_to_name(hdl, destsnap,
                    drrb->drr_fromguid, B_FALSE, origin) != 0) {
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "local origin for clone %s does not exist"),
                            destsnap);
                        err = zfs_error(hdl, EZFS_NOENT, errbuf);
                        goto out;
                }
                if (flags->verbose)
                        (void) printf("found clone origin %s\n", origin);
        }

        boolean_t resuming = DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo) &
            DMU_BACKUP_FEATURE_RESUMING;
        stream_wantsnewfs = (drrb->drr_fromguid == 0 ||
            (drrb->drr_flags & DRR_FLAG_CLONE) || originsnap) && !resuming;

        if (stream_wantsnewfs) {
                /*
                 * if the parent fs does not exist, look for it based on
                 * the parent snap GUID
                 */
                (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
                    "cannot receive new filesystem stream"));

                (void) strcpy(name, destsnap);
                cp = strrchr(name, '/');
                if (cp)
                        *cp = '\0';
                if (cp &&
                    !zfs_dataset_exists(hdl, name, ZFS_TYPE_DATASET)) {
                        char suffix[ZFS_MAX_DATASET_NAME_LEN];
                        (void) strcpy(suffix, strrchr(destsnap, '/'));
                        if (guid_to_name(hdl, name, parent_snapguid,
                            B_FALSE, destsnap) == 0) {
                                *strchr(destsnap, '@') = '\0';
                                (void) strcat(destsnap, suffix);
                        }
                }
        } else {
                /*
                 * if the fs does not exist, look for it based on the
                 * fromsnap GUID
                 */
                (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
                    "cannot receive incremental stream"));

                (void) strcpy(name, destsnap);
                *strchr(name, '@') = '\0';

                /*
                 * If the exact receive path was specified and this is the
                 * topmost path in the stream, then if the fs does not exist we
                 * should look no further.
                 */
                if ((flags->isprefix || (*(chopprefix = drrb->drr_toname +
                    strlen(sendfs)) != '\0' && *chopprefix != '@')) &&
                    !zfs_dataset_exists(hdl, name, ZFS_TYPE_DATASET)) {
                        char snap[ZFS_MAX_DATASET_NAME_LEN];
                        (void) strcpy(snap, strchr(destsnap, '@'));
                        if (guid_to_name(hdl, name, drrb->drr_fromguid,
                            B_FALSE, destsnap) == 0) {
                                *strchr(destsnap, '@') = '\0';
                                (void) strcat(destsnap, snap);
                        }
                }
        }

        (void) strcpy(name, destsnap);
        *strchr(name, '@') = '\0';

        if (zfs_dataset_exists(hdl, name, ZFS_TYPE_DATASET)) {
                zfs_cmd_t zc = {"\0"};
                zfs_handle_t *zhp;

                (void) strcpy(zc.zc_name, name);

                /*
                 * Destination fs exists.  It must be one of these cases:
                 *  - an incremental send stream
                 *  - the stream specifies a new fs (full stream or clone)
                 *    and they want us to blow away the existing fs (and
                 *    have therefore specified -F and removed any snapshots)
                 *  - we are resuming a failed receive.
                 */
                if (stream_wantsnewfs) {
                        if (!flags->force) {
                                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                                    "destination '%s' exists\n"
                                    "must specify -F to overwrite it"), name);
                                err = zfs_error(hdl, EZFS_EXISTS, errbuf);
                                goto out;
                        }
                        if (ioctl(hdl->libzfs_fd, ZFS_IOC_SNAPSHOT_LIST_NEXT,
                            &zc) == 0) {
                                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                                    "destination has snapshots (eg. %s)\n"
                                    "must destroy them to overwrite it"),
                                    name);
                                err = zfs_error(hdl, EZFS_EXISTS, errbuf);
                                goto out;
                        }
                }

                if ((zhp = zfs_open(hdl, name,
                    ZFS_TYPE_FILESYSTEM | ZFS_TYPE_VOLUME)) == NULL) {
                        err = -1;
                        goto out;
                }

                if (stream_wantsnewfs &&
                    zhp->zfs_dmustats.dds_origin[0]) {
                        zfs_close(zhp);
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "destination '%s' is a clone\n"
                            "must destroy it to overwrite it"), name);
                        err = zfs_error(hdl, EZFS_EXISTS, errbuf);
                        goto out;
                }

                if (!flags->dryrun && zhp->zfs_type == ZFS_TYPE_FILESYSTEM &&
                    stream_wantsnewfs) {
                        /* We can't do online recv in this case */
                        clp = changelist_gather(zhp, ZFS_PROP_NAME, 0, 0);
                        if (clp == NULL) {
                                zfs_close(zhp);
                                err = -1;
                                goto out;
                        }
                        if (changelist_prefix(clp) != 0) {
                                changelist_free(clp);
                                zfs_close(zhp);
                                err = -1;
                                goto out;
                        }
                }

                /*
                 * If we are resuming a newfs, set newfs here so that we will
                 * mount it if the recv succeeds this time.  We can tell
                 * that it was a newfs on the first recv because the fs
                 * itself will be inconsistent (if the fs existed when we
                 * did the first recv, we would have received it into
                 * .../%recv).
                 */
                if (resuming && zfs_prop_get_int(zhp, ZFS_PROP_INCONSISTENT))
                        newfs = B_TRUE;

                zfs_close(zhp);
        } else {
                /*
                 * Destination filesystem does not exist.  Therefore we better
                 * be creating a new filesystem (either from a full backup, or
                 * a clone).  It would therefore be invalid if the user
                 * specified only the pool name (i.e. if the destination name
                 * contained no slash character).
                 */
                cp = strrchr(name, '/');

                if (!stream_wantsnewfs || cp == NULL) {
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "destination '%s' does not exist"), name);
                        err = zfs_error(hdl, EZFS_NOENT, errbuf);
                        goto out;
                }

                /*
                 * Trim off the final dataset component so we perform the
                 * recvbackup ioctl to the filesystems's parent.
                 */
                *cp = '\0';

                if (flags->isprefix && !flags->istail && !flags->dryrun &&
                    create_parents(hdl, destsnap, strlen(tosnap)) != 0) {
                        err = zfs_error(hdl, EZFS_BADRESTORE, errbuf);
                        goto out;
                }

                newfs = B_TRUE;
        }

        if (flags->verbose) {
                (void) printf("%s %s stream of %s into %s\n",
                    flags->dryrun ? "would receive" : "receiving",
                    drrb->drr_fromguid ? "incremental" : "full",
                    drrb->drr_toname, destsnap);
                (void) fflush(stdout);
        }

        if (flags->dryrun) {
                err = recv_skip(hdl, infd, flags->byteswap);
                goto out;
        }

        err = ioctl_err = lzc_receive_one(destsnap, props, origin,
            flags->force, flags->resumable, infd, drr_noswap, cleanup_fd,
            &read_bytes, &errflags, action_handlep, &prop_errors);
        ioctl_errno = ioctl_err;
        prop_errflags = errflags;

        if (err == 0) {
                nvpair_t *prop_err = NULL;

                while ((prop_err = nvlist_next_nvpair(prop_errors,
                    prop_err)) != NULL) {
                        char tbuf[1024];
                        zfs_prop_t prop;
                        int intval;

                        prop = zfs_name_to_prop(nvpair_name(prop_err));
                        (void) nvpair_value_int32(prop_err, &intval);
                        if (strcmp(nvpair_name(prop_err),
                            ZPROP_N_MORE_ERRORS) == 0) {
                                trunc_prop_errs(intval);
                                break;
                        } else if (snapname == NULL || finalsnap == NULL ||
                            strcmp(finalsnap, snapname) == 0 ||
                            strcmp(nvpair_name(prop_err),
                            zfs_prop_to_name(ZFS_PROP_REFQUOTA)) != 0) {
                                /*
                                 * Skip the special case of, for example,
                                 * "refquota", errors on intermediate
                                 * snapshots leading up to a final one.
                                 * That's why we have all of the checks above.
                                 *
                                 * See zfs_ioctl.c's extract_delay_props() for
                                 * a list of props which can fail on
                                 * intermediate snapshots, but shouldn't
                                 * affect the overall receive.
                                 */
                                (void) snprintf(tbuf, sizeof (tbuf),
                                    dgettext(TEXT_DOMAIN,
                                    "cannot receive %s property on %s"),
                                    nvpair_name(prop_err), name);
                                zfs_setprop_error(hdl, prop, intval, tbuf);
                        }
                }
        }

        if (err == 0 && snapprops_nvlist) {
                zfs_cmd_t zc = {"\0"};

                (void) strcpy(zc.zc_name, destsnap);
                zc.zc_cookie = B_TRUE; /* received */
                if (zcmd_write_src_nvlist(hdl, &zc, snapprops_nvlist) == 0) {
                        (void) zfs_ioctl(hdl, ZFS_IOC_SET_PROP, &zc);
                        zcmd_free_nvlists(&zc);
                }
        }

        if (err && (ioctl_errno == ENOENT || ioctl_errno == EEXIST)) {
                /*
                 * It may be that this snapshot already exists,
                 * in which case we want to consume & ignore it
                 * rather than failing.
                 */
                avl_tree_t *local_avl;
                nvlist_t *local_nv, *fs;
                cp = strchr(destsnap, '@');

                /*
                 * XXX Do this faster by just iterating over snaps in
                 * this fs.  Also if zc_value does not exist, we will
                 * get a strange "does not exist" error message.
                 */
                *cp = '\0';
                if (gather_nvlist(hdl, destsnap, NULL, NULL, B_FALSE,
                    B_FALSE, &local_nv, &local_avl) == 0) {
                        *cp = '@';
                        fs = fsavl_find(local_avl, drrb->drr_toguid, NULL);
                        fsavl_destroy(local_avl);
                        nvlist_free(local_nv);

                        if (fs != NULL) {
                                if (flags->verbose) {
                                        (void) printf("snap %s already exists; "
                                            "ignoring\n", destsnap);
                                }
                                err = ioctl_err = recv_skip(hdl, infd,
                                    flags->byteswap);
                        }
                }
                *cp = '@';
        }

        if (ioctl_err != 0) {
                switch (ioctl_errno) {
                case ENODEV:
                        cp = strchr(destsnap, '@');
                        *cp = '\0';
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "most recent snapshot of %s does not\n"
                            "match incremental source"), destsnap);
                        (void) zfs_error(hdl, EZFS_BADRESTORE, errbuf);
                        *cp = '@';
                        break;
                case ETXTBSY:
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "destination %s has been modified\n"
                            "since most recent snapshot"), name);
                        (void) zfs_error(hdl, EZFS_BADRESTORE, errbuf);
                        break;
                case EEXIST:
                        cp = strchr(destsnap, '@');
                        if (newfs) {
                                /* it's the containing fs that exists */
                                *cp = '\0';
                        }
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "destination already exists"));
                        (void) zfs_error_fmt(hdl, EZFS_EXISTS,
                            dgettext(TEXT_DOMAIN, "cannot restore to %s"),
                            destsnap);
                        *cp = '@';
                        break;
                case EINVAL:
                        if (flags->resumable)
                                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                                    "kernel modules must be upgraded to "
                                    "receive this stream."));
                        (void) zfs_error(hdl, EZFS_BADSTREAM, errbuf);
                        break;
                case ECKSUM:
                        recv_ecksum_set_aux(hdl, destsnap, flags->resumable);
                        (void) zfs_error(hdl, EZFS_BADSTREAM, errbuf);
                        break;
                case ENOTSUP:
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "pool must be upgraded to receive this stream."));
                        (void) zfs_error(hdl, EZFS_BADVERSION, errbuf);
                        break;
                case EDQUOT:
                        zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                            "destination %s space quota exceeded"), name);
                        (void) zfs_error(hdl, EZFS_NOSPC, errbuf);
                        break;
                default:
                        (void) zfs_standard_error(hdl, ioctl_errno, errbuf);
                }
        }

        /*
         * Mount the target filesystem (if created).  Also mount any
         * children of the target filesystem if we did a replication
         * receive (indicated by stream_avl being non-NULL).
         */
        cp = strchr(destsnap, '@');
        if (cp && (ioctl_err == 0 || !newfs)) {
                zfs_handle_t *h;

                *cp = '\0';
                h = zfs_open(hdl, destsnap,
                    ZFS_TYPE_FILESYSTEM | ZFS_TYPE_VOLUME);
                if (h != NULL) {
                        if (h->zfs_type == ZFS_TYPE_VOLUME) {
                                *cp = '@';
                        } else if (newfs || stream_avl) {
                                /*
                                 * Track the first/top of hierarchy fs,
                                 * for mounting and sharing later.
                                 */
                                if (top_zfs && *top_zfs == NULL)
                                        *top_zfs = zfs_strdup(hdl, destsnap);
                        }
                        zfs_close(h);
                }
                *cp = '@';
        }

        if (clp) {
                if (!flags->nomount)
                        err |= changelist_postfix(clp);
                changelist_free(clp);
        }

        if (prop_errflags & ZPROP_ERR_NOCLEAR) {
                (void) fprintf(stderr, dgettext(TEXT_DOMAIN, "Warning: "
                    "failed to clear unreceived properties on %s"), name);
                (void) fprintf(stderr, "\n");
        }
        if (prop_errflags & ZPROP_ERR_NORESTORE) {
                (void) fprintf(stderr, dgettext(TEXT_DOMAIN, "Warning: "
                    "failed to restore original properties on %s"), name);
                (void) fprintf(stderr, "\n");
        }

        if (err || ioctl_err) {
                err = -1;
                goto out;
        }

        if (flags->verbose) {
                char buf1[64];
                char buf2[64];
                uint64_t bytes = read_bytes;
                time_t delta = time(NULL) - begin_time;
                if (delta == 0)
                        delta = 1;
                zfs_nicenum(bytes, buf1, sizeof (buf1));
                zfs_nicenum(bytes/delta, buf2, sizeof (buf1));

                (void) printf("received %sB stream in %lu seconds (%sB/sec)\n",
                    buf1, delta, buf2);
        }

        err = 0;
out:
        if (prop_errors != NULL)
                nvlist_free(prop_errors);

        if (newprops)
                nvlist_free(props);

        return (err);
}

static int
zfs_receive_impl(libzfs_handle_t *hdl, const char *tosnap,
    const char *originsnap, recvflags_t *flags, int infd, const char *sendfs,
    nvlist_t *stream_nv, avl_tree_t *stream_avl, char **top_zfs, int cleanup_fd,
    uint64_t *action_handlep, const char *finalsnap)
{
        int err;
        dmu_replay_record_t drr, drr_noswap;
        struct drr_begin *drrb = &drr.drr_u.drr_begin;
        char errbuf[1024];
        zio_cksum_t zcksum = { { 0 } };
        uint64_t featureflags;
        int hdrtype;

        (void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
            "cannot receive"));

        if (flags->isprefix &&
            !zfs_dataset_exists(hdl, tosnap, ZFS_TYPE_DATASET)) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "specified fs "
                    "(%s) does not exist"), tosnap);
                return (zfs_error(hdl, EZFS_NOENT, errbuf));
        }
        if (originsnap &&
            !zfs_dataset_exists(hdl, originsnap, ZFS_TYPE_DATASET)) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "specified origin fs "
                    "(%s) does not exist"), originsnap);
                return (zfs_error(hdl, EZFS_NOENT, errbuf));
        }

        /* read in the BEGIN record */
        if (0 != (err = recv_read(hdl, infd, &drr, sizeof (drr), B_FALSE,
            &zcksum)))
                return (err);

        if (drr.drr_type == DRR_END || drr.drr_type == BSWAP_32(DRR_END)) {
                /* It's the double end record at the end of a package */
                return (ENODATA);
        }

        /* the kernel needs the non-byteswapped begin record */
        drr_noswap = drr;

        flags->byteswap = B_FALSE;
        if (drrb->drr_magic == BSWAP_64(DMU_BACKUP_MAGIC)) {
                /*
                 * We computed the checksum in the wrong byteorder in
                 * recv_read() above; do it again correctly.
                 */
                bzero(&zcksum, sizeof (zio_cksum_t));
                fletcher_4_incremental_byteswap(&drr, sizeof (drr), &zcksum);
                flags->byteswap = B_TRUE;

                drr.drr_type = BSWAP_32(drr.drr_type);
                drr.drr_payloadlen = BSWAP_32(drr.drr_payloadlen);
                drrb->drr_magic = BSWAP_64(drrb->drr_magic);
                drrb->drr_versioninfo = BSWAP_64(drrb->drr_versioninfo);
                drrb->drr_creation_time = BSWAP_64(drrb->drr_creation_time);
                drrb->drr_type = BSWAP_32(drrb->drr_type);
                drrb->drr_flags = BSWAP_32(drrb->drr_flags);
                drrb->drr_toguid = BSWAP_64(drrb->drr_toguid);
                drrb->drr_fromguid = BSWAP_64(drrb->drr_fromguid);
        }

        if (drrb->drr_magic != DMU_BACKUP_MAGIC || drr.drr_type != DRR_BEGIN) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "invalid "
                    "stream (bad magic number)"));
                return (zfs_error(hdl, EZFS_BADSTREAM, errbuf));
        }

        featureflags = DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo);
        hdrtype = DMU_GET_STREAM_HDRTYPE(drrb->drr_versioninfo);

        if (!DMU_STREAM_SUPPORTED(featureflags) ||
            (hdrtype != DMU_SUBSTREAM && hdrtype != DMU_COMPOUNDSTREAM)) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
                    "stream has unsupported feature, feature flags = %lx"),
                    featureflags);
                return (zfs_error(hdl, EZFS_BADSTREAM, errbuf));
        }

        if (strchr(drrb->drr_toname, '@') == NULL) {
                zfs_error_aux(hdl, dgettext(TEXT_DOMAIN, "invalid "
                    "stream (bad snapshot name)"));
                return (zfs_error(hdl, EZFS_BADSTREAM, errbuf));
        }

        if (DMU_GET_STREAM_HDRTYPE(drrb->drr_versioninfo) == DMU_SUBSTREAM) {
                char nonpackage_sendfs[ZFS_MAX_DATASET_NAME_LEN];
                if (sendfs == NULL) {
                        /*
                         * We were not called from zfs_receive_package(). Get
                         * the fs specified by 'zfs send'.
                         */
                        char *cp;
                        (void) strlcpy(nonpackage_sendfs,
                            drr.drr_u.drr_begin.drr_toname,
                            sizeof (nonpackage_sendfs));
                        if ((cp = strchr(nonpackage_sendfs, '@')) != NULL)
                                *cp = '\0';
                        sendfs = nonpackage_sendfs;
                        VERIFY(finalsnap == NULL);
                }
                return (zfs_receive_one(hdl, infd, tosnap, originsnap, flags,
                    &drr, &drr_noswap, sendfs, stream_nv, stream_avl, top_zfs,
                    cleanup_fd, action_handlep, finalsnap));
        } else {
                assert(DMU_GET_STREAM_HDRTYPE(drrb->drr_versioninfo) ==
                    DMU_COMPOUNDSTREAM);
                return (zfs_receive_package(hdl, infd, tosnap, flags, &drr,
                    &zcksum, top_zfs, cleanup_fd, action_handlep));
        }
}

/*
 * Restores a backup of tosnap from the file descriptor specified by infd.
 * Return 0 on total success, -2 if some things couldn't be
 * destroyed/renamed/promoted, -1 if some things couldn't be received.
 * (-1 will override -2, if -1 and the resumable flag was specified the
 * transfer can be resumed if the sending side supports it).
 */
int
zfs_receive(libzfs_handle_t *hdl, const char *tosnap, nvlist_t *props,
    recvflags_t *flags, int infd, avl_tree_t *stream_avl)
{
        char *top_zfs = NULL;
        int err;
        int cleanup_fd;
        uint64_t action_handle = 0;
        struct stat sb;
        char *originsnap = NULL;

        /*
         * The only way fstat can fail is if we do not have a valid file
         * descriptor.
         */
        if (fstat(infd, &sb) == -1) {
                perror("fstat");
                return (-2);
        }

#ifdef __linux__
#ifndef F_SETPIPE_SZ
#define F_SETPIPE_SZ (F_SETLEASE + 7)
#endif /* F_SETPIPE_SZ */

#ifndef F_GETPIPE_SZ
#define F_GETPIPE_SZ (F_GETLEASE + 7)
#endif /* F_GETPIPE_SZ */

        /*
         * It is not uncommon for gigabytes to be processed in zfs receive.
         * Speculatively increase the buffer size via Linux-specific fcntl()
         * call.
         */
        if (S_ISFIFO(sb.st_mode)) {
                FILE *procf = fopen("/proc/sys/fs/pipe-max-size", "r");

                if (procf != NULL) {
                        unsigned long max_psize;
                        long cur_psize;
                        if (fscanf(procf, "%lu", &max_psize) > 0) {
                                cur_psize = fcntl(infd, F_GETPIPE_SZ);
                                if (cur_psize > 0 &&
                                    max_psize > (unsigned long) cur_psize)
                                        (void) fcntl(infd, F_SETPIPE_SZ,
                                            max_psize);
                        }
                        fclose(procf);
                }
        }
#endif /* __linux__ */

        if (props) {
                err = nvlist_lookup_string(props, "origin", &originsnap);
                if (err && err != ENOENT)
                        return (err);
        }

        cleanup_fd = open(ZFS_DEV, O_RDWR);
        VERIFY(cleanup_fd >= 0);

        err = zfs_receive_impl(hdl, tosnap, originsnap, flags, infd, NULL, NULL,
            stream_avl, &top_zfs, cleanup_fd, &action_handle, NULL);

        VERIFY(0 == close(cleanup_fd));

        if (err == 0 && !flags->nomount && top_zfs) {
                zfs_handle_t *zhp = NULL;
                prop_changelist_t *clp = NULL;

                zhp = zfs_open(hdl, top_zfs, ZFS_TYPE_FILESYSTEM);
                if (zhp != NULL) {
                        clp = changelist_gather(zhp, ZFS_PROP_MOUNTPOINT,
                            CL_GATHER_MOUNT_ALWAYS, 0);
                        zfs_close(zhp);
                        if (clp != NULL) {
                                /* mount and share received datasets */
                                err = changelist_postfix(clp);
                                changelist_free(clp);
                        }
                }
                if (zhp == NULL || clp == NULL || err)
                        err = -1;
        }
        if (top_zfs)
                free(top_zfs);

        return (err);
}