// SPDX-License-Identifier: GPL-2.0+
/*
 *
 * ZFS filesystem ported to u-boot by
 * Jorgen Lundman <lundman at lundman.net>
 *
 *      GRUB  --  GRand Unified Bootloader
 *      Copyright (C) 1999,2000,2001,2002,2003,2004
 *      Free Software Foundation, Inc.
 *      Copyright 2004  Sun Microsystems, Inc.
 */

#include <common.h>
#include <log.h>
#include <malloc.h>
#include <linux/stat.h>
#include <linux/time.h>
#include <linux/ctype.h>
#include <asm/byteorder.h>
#include "zfs_common.h"
#include "div64.h"

struct blk_desc *zfs_dev_desc;

/*
 * The zfs plug-in routines for GRUB are:
 *
 * zfs_mount() - locates a valid uberblock of the root pool and reads
 *              in its MOS at the memory address MOS.
 *
 * zfs_open() - locates a plain file object by following the MOS
 *              and places its dnode at the memory address DNODE.
 *
 * zfs_read() - read in the data blocks pointed by the DNODE.
 *
 */

#include <zfs/zfs.h>
#include <zfs/zio.h>
#include <zfs/dnode.h>
#include <zfs/uberblock_impl.h>
#include <zfs/vdev_impl.h>
#include <zfs/zio_checksum.h>
#include <zfs/zap_impl.h>
#include <zfs/zap_leaf.h>
#include <zfs/zfs_znode.h>
#include <zfs/dmu.h>
#include <zfs/dmu_objset.h>
#include <zfs/sa_impl.h>
#include <zfs/dsl_dir.h>
#include <zfs/dsl_dataset.h>


#define ZPOOL_PROP_BOOTFS               "bootfs"


/*
 * For nvlist manipulation. (from nvpair.h)
 */
#define NV_ENCODE_NATIVE        0
#define NV_ENCODE_XDR           1
#define NV_BIG_ENDIAN                   0
#define NV_LITTLE_ENDIAN        1
#define DATA_TYPE_UINT64        8
#define DATA_TYPE_STRING        9
#define DATA_TYPE_NVLIST        19
#define DATA_TYPE_NVLIST_ARRAY  20


/*
 * Macros to get fields in a bp or DVA.
 */
#define P2PHASE(x, align)               ((x) & ((align) - 1))
#define DVA_OFFSET_TO_PHYS_SECTOR(offset)                                       \
        ((offset + VDEV_LABEL_START_SIZE) >> SPA_MINBLOCKSHIFT)

/*
 * return x rounded down to an align boundary
 * eg, P2ALIGN(1200, 1024) == 1024 (1*align)
 * eg, P2ALIGN(1024, 1024) == 1024 (1*align)
 * eg, P2ALIGN(0x1234, 0x100) == 0x1200 (0x12*align)
 * eg, P2ALIGN(0x5600, 0x100) == 0x5600 (0x56*align)
 */
#define P2ALIGN(x, align)               ((x) & -(align))

/*
 * FAT ZAP data structures
 */
#define ZFS_CRC64_POLY 0xC96C5795D7870F42ULL    /* ECMA-182, reflected form */
#define ZAP_HASH_IDX(hash, n)   (((n) == 0) ? 0 : ((hash) >> (64 - (n))))
#define CHAIN_END       0xffff  /* end of the chunk chain */

/*
 * The amount of space within the chunk available for the array is:
 * chunk size - space for type (1) - space for next pointer (2)
 */
#define ZAP_LEAF_ARRAY_BYTES (ZAP_LEAF_CHUNKSIZE - 3)

#define ZAP_LEAF_HASH_SHIFT(bs) (bs - 5)
#define ZAP_LEAF_HASH_NUMENTRIES(bs) (1 << ZAP_LEAF_HASH_SHIFT(bs))
#define LEAF_HASH(bs, h)                                                                                                \
        ((ZAP_LEAF_HASH_NUMENTRIES(bs)-1) &                                                                     \
         ((h) >> (64 - ZAP_LEAF_HASH_SHIFT(bs)-l->l_hdr.lh_prefix_len)))

/*
 * The amount of space available for chunks is:
 * block size shift - hash entry size (2) * number of hash
 * entries - header space (2*chunksize)
 */
#define ZAP_LEAF_NUMCHUNKS(bs)                                          \
        (((1<<bs) - 2*ZAP_LEAF_HASH_NUMENTRIES(bs)) /   \
         ZAP_LEAF_CHUNKSIZE - 2)

/*
 * The chunks start immediately after the hash table.  The end of the
 * hash table is at l_hash + HASH_NUMENTRIES, which we simply cast to a
 * chunk_t.
 */
#define ZAP_LEAF_CHUNK(l, bs, idx)                                                                              \
        ((zap_leaf_chunk_t *)(l->l_hash + ZAP_LEAF_HASH_NUMENTRIES(bs)))[idx]
#define ZAP_LEAF_ENTRY(l, bs, idx) (&ZAP_LEAF_CHUNK(l, bs, idx).l_entry)


/*
 * Decompression Entry - lzjb
 */
#ifndef NBBY
#define NBBY    8
#endif



typedef int zfs_decomp_func_t(void *s_start, void *d_start,
                                                          uint32_t s_len, uint32_t d_len);
typedef struct decomp_entry {
        char *name;
        zfs_decomp_func_t *decomp_func;
} decomp_entry_t;

typedef struct dnode_end {
        dnode_phys_t dn;
        zfs_endian_t endian;
} dnode_end_t;

struct zfs_data {
        /* cache for a file block of the currently zfs_open()-ed file */
        char *file_buf;
        uint64_t file_start;
        uint64_t file_end;

        /* XXX: ashift is per vdev, not per pool.  We currently only ever touch
         * a single vdev, but when/if raid-z or stripes are supported, this
         * may need revision.
         */
        uint64_t vdev_ashift;
        uint64_t label_txg;
        uint64_t pool_guid;

        /* cache for a dnode block */
        dnode_phys_t *dnode_buf;
        dnode_phys_t *dnode_mdn;
        uint64_t dnode_start;
        uint64_t dnode_end;
        zfs_endian_t dnode_endian;

        uberblock_t current_uberblock;

        dnode_end_t mos;
        dnode_end_t mdn;
        dnode_end_t dnode;

        uint64_t vdev_phys_sector;

        int (*userhook)(const char *, const struct zfs_dirhook_info *);
        struct zfs_dirhook_info *dirinfo;

};




static int
zlib_decompress(void *s, void *d,
                                uint32_t slen, uint32_t dlen)
{
        if (zlib_decompress(s, d, slen, dlen) < 0)
                return ZFS_ERR_BAD_FS;
        return ZFS_ERR_NONE;
}

static decomp_entry_t decomp_table[ZIO_COMPRESS_FUNCTIONS] = {
        {"inherit", NULL},              /* ZIO_COMPRESS_INHERIT */
        {"on", lzjb_decompress},        /* ZIO_COMPRESS_ON */
        {"off", NULL},          /* ZIO_COMPRESS_OFF */
        {"lzjb", lzjb_decompress},      /* ZIO_COMPRESS_LZJB */
        {"empty", NULL},                /* ZIO_COMPRESS_EMPTY */
        {"gzip-1", zlib_decompress},  /* ZIO_COMPRESS_GZIP1 */
        {"gzip-2", zlib_decompress},  /* ZIO_COMPRESS_GZIP2 */
        {"gzip-3", zlib_decompress},  /* ZIO_COMPRESS_GZIP3 */
        {"gzip-4", zlib_decompress},  /* ZIO_COMPRESS_GZIP4 */
        {"gzip-5", zlib_decompress},  /* ZIO_COMPRESS_GZIP5 */
        {"gzip-6", zlib_decompress},  /* ZIO_COMPRESS_GZIP6 */
        {"gzip-7", zlib_decompress},  /* ZIO_COMPRESS_GZIP7 */
        {"gzip-8", zlib_decompress},  /* ZIO_COMPRESS_GZIP8 */
        {"gzip-9", zlib_decompress},  /* ZIO_COMPRESS_GZIP9 */
};



static int zio_read_data(blkptr_t *bp, zfs_endian_t endian,
                                                 void *buf, struct zfs_data *data);

static int
zio_read(blkptr_t *bp, zfs_endian_t endian, void **buf,
                 size_t *size, struct zfs_data *data);

/*
 * Our own version of log2().  Same thing as highbit()-1.
 */
static int
zfs_log2(uint64_t num)
{
        int i = 0;

        while (num > 1) {
                i++;
                num = num >> 1;
        }

        return i;
}


/* Checksum Functions */
static void
zio_checksum_off(const void *buf __attribute__ ((unused)),
                                 uint64_t size __attribute__ ((unused)),
                                 zfs_endian_t endian __attribute__ ((unused)),
                                 zio_cksum_t *zcp)
{
        ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
}

/* Checksum Table and Values */
static zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
        {NULL, 0, 0, "inherit"},
        {NULL, 0, 0, "on"},
        {zio_checksum_off, 0, 0, "off"},
        {zio_checksum_SHA256, 1, 1, "label"},
        {zio_checksum_SHA256, 1, 1, "gang_header"},
        {NULL, 0, 0, "zilog"},
        {fletcher_2_endian, 0, 0, "fletcher2"},
        {fletcher_4_endian, 1, 0, "fletcher4"},
        {zio_checksum_SHA256, 1, 0, "SHA256"},
        {NULL, 0, 0, "zilog2"},
};

/*
 * zio_checksum_verify: Provides support for checksum verification.
 *
 * Fletcher2, Fletcher4, and SHA256 are supported.
 *
 */
static int
zio_checksum_verify(zio_cksum_t zc, uint32_t checksum,
                                        zfs_endian_t endian, char *buf, int size)
{
        zio_eck_t *zec = (zio_eck_t *) (buf + size) - 1;
        zio_checksum_info_t *ci = &zio_checksum_table[checksum];
        zio_cksum_t actual_cksum, expected_cksum;

        if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func == NULL) {
                printf("zfs unknown checksum function %d\n", checksum);
                return ZFS_ERR_NOT_IMPLEMENTED_YET;
        }

        if (ci->ci_eck) {
                expected_cksum = zec->zec_cksum;
                zec->zec_cksum = zc;
                ci->ci_func(buf, size, endian, &actual_cksum);
                zec->zec_cksum = expected_cksum;
                zc = expected_cksum;
        } else {
                ci->ci_func(buf, size, endian, &actual_cksum);
        }

        if ((actual_cksum.zc_word[0] != zc.zc_word[0])
                || (actual_cksum.zc_word[1] != zc.zc_word[1])
                || (actual_cksum.zc_word[2] != zc.zc_word[2])
                || (actual_cksum.zc_word[3] != zc.zc_word[3])) {
                return ZFS_ERR_BAD_FS;
        }

        return ZFS_ERR_NONE;
}

/*
 * vdev_uberblock_compare takes two uberblock structures and returns an integer
 * indicating the more recent of the two.
 *      Return Value = 1 if ub2 is more recent
 *      Return Value = -1 if ub1 is more recent
 * The most recent uberblock is determined using its transaction number and
 * timestamp.  The uberblock with the highest transaction number is
 * considered "newer".  If the transaction numbers of the two blocks match, the
 * timestamps are compared to determine the "newer" of the two.
 */
static int
vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2)
{
        zfs_endian_t ub1_endian, ub2_endian;
        if (zfs_to_cpu64(ub1->ub_magic, LITTLE_ENDIAN) == UBERBLOCK_MAGIC)
                ub1_endian = LITTLE_ENDIAN;
        else
                ub1_endian = BIG_ENDIAN;
        if (zfs_to_cpu64(ub2->ub_magic, LITTLE_ENDIAN) == UBERBLOCK_MAGIC)
                ub2_endian = LITTLE_ENDIAN;
        else
                ub2_endian = BIG_ENDIAN;

        if (zfs_to_cpu64(ub1->ub_txg, ub1_endian)
                < zfs_to_cpu64(ub2->ub_txg, ub2_endian))
                return -1;
        if (zfs_to_cpu64(ub1->ub_txg, ub1_endian)
                > zfs_to_cpu64(ub2->ub_txg, ub2_endian))
                return 1;

        if (zfs_to_cpu64(ub1->ub_timestamp, ub1_endian)
                < zfs_to_cpu64(ub2->ub_timestamp, ub2_endian))
                return -1;
        if (zfs_to_cpu64(ub1->ub_timestamp, ub1_endian)
                > zfs_to_cpu64(ub2->ub_timestamp, ub2_endian))
                return 1;

        return 0;
}

/*
 * Three pieces of information are needed to verify an uberblock: the magic
 * number, the version number, and the checksum.
 *
 * Currently Implemented: version number, magic number, label txg
 * Need to Implement: checksum
 *
 */
static int
uberblock_verify(uberblock_t *uber, int offset, struct zfs_data *data)
{
        int err;
        zfs_endian_t endian = UNKNOWN_ENDIAN;
        zio_cksum_t zc;

        if (uber->ub_txg < data->label_txg) {
                debug("ignoring partially written label: uber_txg < label_txg %llu %llu\n",
                          uber->ub_txg, data->label_txg);
                return ZFS_ERR_BAD_FS;
        }

        if (zfs_to_cpu64(uber->ub_magic, LITTLE_ENDIAN) == UBERBLOCK_MAGIC
                && zfs_to_cpu64(uber->ub_version, LITTLE_ENDIAN) > 0
                && zfs_to_cpu64(uber->ub_version, LITTLE_ENDIAN) <= SPA_VERSION)
                endian = LITTLE_ENDIAN;

        if (zfs_to_cpu64(uber->ub_magic, BIG_ENDIAN) == UBERBLOCK_MAGIC
                && zfs_to_cpu64(uber->ub_version, BIG_ENDIAN) > 0
                && zfs_to_cpu64(uber->ub_version, BIG_ENDIAN) <= SPA_VERSION)
                endian = BIG_ENDIAN;

        if (endian == UNKNOWN_ENDIAN) {
                printf("invalid uberblock magic\n");
                return ZFS_ERR_BAD_FS;
        }

        memset(&zc, 0, sizeof(zc));
        zc.zc_word[0] = cpu_to_zfs64(offset, endian);
        err = zio_checksum_verify(zc, ZIO_CHECKSUM_LABEL, endian,
                                                          (char *) uber, UBERBLOCK_SIZE(data->vdev_ashift));

        if (!err) {
                /* Check that the data pointed by the rootbp is usable. */
                void *osp = NULL;
                size_t ospsize;
                err = zio_read(&uber->ub_rootbp, endian, &osp, &ospsize, data);
                free(osp);

                if (!err && ospsize < OBJSET_PHYS_SIZE_V14) {
                        printf("uberblock rootbp points to invalid data\n");
                        return ZFS_ERR_BAD_FS;
                }
        }

        return err;
}

/*
 * Find the best uberblock.
 * Return:
 *        Success - Pointer to the best uberblock.
 *        Failure - NULL
 */
static uberblock_t *find_bestub(char *ub_array, struct zfs_data *data)
{
        const uint64_t sector = data->vdev_phys_sector;
        uberblock_t *ubbest = NULL;
        uberblock_t *ubnext;
        unsigned int i, offset, pickedub = 0;
        int err = ZFS_ERR_NONE;

        const unsigned int UBCOUNT = UBERBLOCK_COUNT(data->vdev_ashift);
        const uint64_t UBBYTES = UBERBLOCK_SIZE(data->vdev_ashift);

        for (i = 0; i < UBCOUNT; i++) {
                ubnext = (uberblock_t *) (i * UBBYTES + ub_array);
                offset = (sector << SPA_MINBLOCKSHIFT) + VDEV_PHYS_SIZE + (i * UBBYTES);

                err = uberblock_verify(ubnext, offset, data);
                if (err)
                        continue;

                if (ubbest == NULL || vdev_uberblock_compare(ubnext, ubbest) > 0) {
                        ubbest = ubnext;
                        pickedub = i;
                }
        }

        if (ubbest)
                debug("zfs Found best uberblock at idx %d, txg %llu\n",
                          pickedub, (unsigned long long) ubbest->ub_txg);

        return ubbest;
}

static inline size_t
get_psize(blkptr_t *bp, zfs_endian_t endian)
{
        return (((zfs_to_cpu64((bp)->blk_prop, endian) >> 16) & 0xffff) + 1)
                        << SPA_MINBLOCKSHIFT;
}

static uint64_t
dva_get_offset(dva_t *dva, zfs_endian_t endian)
{
        return zfs_to_cpu64((dva)->dva_word[1],
                                                         endian) << SPA_MINBLOCKSHIFT;
}

/*
 * Read a block of data based on the gang block address dva,
 * and put its data in buf.
 *
 */
static int
zio_read_gang(blkptr_t *bp, zfs_endian_t endian, dva_t *dva, void *buf,
                          struct zfs_data *data)
{
        zio_gbh_phys_t *zio_gb;
        uint64_t offset, sector;
        unsigned i;
        int err;
        zio_cksum_t zc;

        memset(&zc, 0, sizeof(zc));

        zio_gb = malloc(SPA_GANGBLOCKSIZE);
        if (!zio_gb)
                return ZFS_ERR_OUT_OF_MEMORY;

        offset = dva_get_offset(dva, endian);
        sector = DVA_OFFSET_TO_PHYS_SECTOR(offset);

        /* read in the gang block header */
        err = zfs_devread(sector, 0, SPA_GANGBLOCKSIZE, (char *) zio_gb);

        if (err) {
                free(zio_gb);
                return err;
        }

        /* XXX */
        /* self checksuming the gang block header */
        ZIO_SET_CHECKSUM(&zc, DVA_GET_VDEV(dva),
                                         dva_get_offset(dva, endian), bp->blk_birth, 0);
        err = zio_checksum_verify(zc, ZIO_CHECKSUM_GANG_HEADER, endian,
                                                          (char *) zio_gb, SPA_GANGBLOCKSIZE);
        if (err) {
                free(zio_gb);
                return err;
        }

        endian = (zfs_to_cpu64(bp->blk_prop, endian) >> 63) & 1;

        for (i = 0; i < SPA_GBH_NBLKPTRS; i++) {
                if (zio_gb->zg_blkptr[i].blk_birth == 0)
                        continue;

                err = zio_read_data(&zio_gb->zg_blkptr[i], endian, buf, data);
                if (err) {
                        free(zio_gb);
                        return err;
                }
                buf = (char *) buf + get_psize(&zio_gb->zg_blkptr[i], endian);
        }
        free(zio_gb);
        return ZFS_ERR_NONE;
}

/*
 * Read in a block of raw data to buf.
 */
static int
zio_read_data(blkptr_t *bp, zfs_endian_t endian, void *buf,
                          struct zfs_data *data)
{
        int i, psize;
        int err = ZFS_ERR_NONE;

        psize = get_psize(bp, endian);

        /* pick a good dva from the block pointer */
        for (i = 0; i < SPA_DVAS_PER_BP; i++) {
                uint64_t offset, sector;

                if (bp->blk_dva[i].dva_word[0] == 0 && bp->blk_dva[i].dva_word[1] == 0)
                        continue;

                if ((zfs_to_cpu64(bp->blk_dva[i].dva_word[1], endian)>>63) & 1) {
                        err = zio_read_gang(bp, endian, &bp->blk_dva[i], buf, data);
                } else {
                        /* read in a data block */
                        offset = dva_get_offset(&bp->blk_dva[i], endian);
                        sector = DVA_OFFSET_TO_PHYS_SECTOR(offset);

                        err = zfs_devread(sector, 0, psize, buf);
                }

                if (!err) {
                        /*Check the underlying checksum before we rule this DVA as "good"*/
                        uint32_t checkalgo = (zfs_to_cpu64((bp)->blk_prop, endian) >> 40) & 0xff;

                        err = zio_checksum_verify(bp->blk_cksum, checkalgo, endian, buf, psize);
                        if (!err)
                                return ZFS_ERR_NONE;
                }

                /* If read failed or checksum bad, reset the error.      Hopefully we've got some more DVA's to try.*/
        }

        if (!err) {
                printf("couldn't find a valid DVA\n");
                err = ZFS_ERR_BAD_FS;
        }

        return err;
}

/*
 * Read in a block of data, verify its checksum, decompress if needed,
 * and put the uncompressed data in buf.
 */
static int
zio_read(blkptr_t *bp, zfs_endian_t endian, void **buf,
                 size_t *size, struct zfs_data *data)
{
        size_t lsize, psize;
        unsigned int comp;
        char *compbuf = NULL;
        int err;

        *buf = NULL;

        comp = (zfs_to_cpu64((bp)->blk_prop, endian)>>32) & 0xff;
        lsize = (BP_IS_HOLE(bp) ? 0 :
                         (((zfs_to_cpu64((bp)->blk_prop, endian) & 0xffff) + 1)
                          << SPA_MINBLOCKSHIFT));
        psize = get_psize(bp, endian);

        if (size)
                *size = lsize;

        if (comp >= ZIO_COMPRESS_FUNCTIONS) {
                printf("compression algorithm %u not supported\n", (unsigned int) comp);
                return ZFS_ERR_NOT_IMPLEMENTED_YET;
        }

        if (comp != ZIO_COMPRESS_OFF && decomp_table[comp].decomp_func == NULL) {
                printf("compression algorithm %s not supported\n", decomp_table[comp].name);
                return ZFS_ERR_NOT_IMPLEMENTED_YET;
        }

        if (comp != ZIO_COMPRESS_OFF) {
                compbuf = malloc(psize);
                if (!compbuf)
                        return ZFS_ERR_OUT_OF_MEMORY;
        } else {
                compbuf = *buf = malloc(lsize);
        }

        err = zio_read_data(bp, endian, compbuf, data);
        if (err) {
                free(compbuf);
                *buf = NULL;
                return err;
        }

        if (comp != ZIO_COMPRESS_OFF) {
                *buf = malloc(lsize);
                if (!*buf) {
                        free(compbuf);
                        return ZFS_ERR_OUT_OF_MEMORY;
                }

                err = decomp_table[comp].decomp_func(compbuf, *buf, psize, lsize);
                free(compbuf);
                if (err) {
                        free(*buf);
                        *buf = NULL;
                        return err;
                }
        }

        return ZFS_ERR_NONE;
}

/*
 * Get the block from a block id.
 * push the block onto the stack.
 *
 */
static int
dmu_read(dnode_end_t *dn, uint64_t blkid, void **buf,
                 zfs_endian_t *endian_out, struct zfs_data *data)
{
        int idx, level;
        blkptr_t *bp_array = dn->dn.dn_blkptr;
        int epbs = dn->dn.dn_indblkshift - SPA_BLKPTRSHIFT;
        blkptr_t *bp;
        void *tmpbuf = 0;
        zfs_endian_t endian;
        int err = ZFS_ERR_NONE;

        bp = malloc(sizeof(blkptr_t));
        if (!bp)
                return ZFS_ERR_OUT_OF_MEMORY;

        endian = dn->endian;
        for (level = dn->dn.dn_nlevels - 1; level >= 0; level--) {
                idx = (blkid >> (epbs * level)) & ((1 << epbs) - 1);
                *bp = bp_array[idx];
                if (bp_array != dn->dn.dn_blkptr) {
                        free(bp_array);
                        bp_array = 0;
                }

                if (BP_IS_HOLE(bp)) {
                        size_t size = zfs_to_cpu16(dn->dn.dn_datablkszsec,
                                                                                        dn->endian)
                                << SPA_MINBLOCKSHIFT;
                        *buf = malloc(size);
                        if (*buf) {
                                err = ZFS_ERR_OUT_OF_MEMORY;
                                break;
                        }
                        memset(*buf, 0, size);
                        endian = (zfs_to_cpu64(bp->blk_prop, endian) >> 63) & 1;
                        break;
                }
                if (level == 0) {
                        err = zio_read(bp, endian, buf, 0, data);
                        endian = (zfs_to_cpu64(bp->blk_prop, endian) >> 63) & 1;
                        break;
                }
                err = zio_read(bp, endian, &tmpbuf, 0, data);
                endian = (zfs_to_cpu64(bp->blk_prop, endian) >> 63) & 1;
                if (err)
                        break;
                bp_array = tmpbuf;
        }
        if (bp_array != dn->dn.dn_blkptr)
                free(bp_array);
        if (endian_out)
                *endian_out = endian;

        free(bp);
        return err;
}

/*
 * mzap_lookup: Looks up property described by "name" and returns the value
 * in "value".
 */
static int
mzap_lookup(mzap_phys_t *zapobj, zfs_endian_t endian,
                        int objsize, char *name, uint64_t * value)
{
        int i, chunks;
        mzap_ent_phys_t *mzap_ent = zapobj->mz_chunk;

        chunks = objsize / MZAP_ENT_LEN - 1;
        for (i = 0; i < chunks; i++) {
                if (strcmp(mzap_ent[i].mze_name, name) == 0) {
                        *value = zfs_to_cpu64(mzap_ent[i].mze_value, endian);
                        return ZFS_ERR_NONE;
                }
        }

        printf("couldn't find '%s'\n", name);
        return ZFS_ERR_FILE_NOT_FOUND;
}

static int
mzap_iterate(mzap_phys_t *zapobj, zfs_endian_t endian, int objsize,
                         int (*hook)(const char *name,
                                                 uint64_t val,
                                                 struct zfs_data *data),
                         struct zfs_data *data)
{
        int i, chunks;
        mzap_ent_phys_t *mzap_ent = zapobj->mz_chunk;

        chunks = objsize / MZAP_ENT_LEN - 1;
        for (i = 0; i < chunks; i++) {
                if (hook(mzap_ent[i].mze_name,
                                 zfs_to_cpu64(mzap_ent[i].mze_value, endian),
                                 data))
                        return 1;
        }

        return 0;
}

static uint64_t
zap_hash(uint64_t salt, const char *name)
{
        static uint64_t table[256];
        const uint8_t *cp;
        uint8_t c;
        uint64_t crc = salt;

        if (table[128] == 0) {
                uint64_t *ct = NULL;
                int i, j;
                for (i = 0; i < 256; i++) {
                        for (ct = table + i, *ct = i, j = 8; j > 0; j--)
                                *ct = (*ct >> 1) ^ (-(*ct & 1) & ZFS_CRC64_POLY);
                }
        }

        for (cp = (const uint8_t *) name; (c = *cp) != '\0'; cp++)
                crc = (crc >> 8) ^ table[(crc ^ c) & 0xFF];

        /*
         * Only use 28 bits, since we need 4 bits in the cookie for the
         * collision differentiator.  We MUST use the high bits, since
         * those are the onces that we first pay attention to when
         * chosing the bucket.
         */
        crc &= ~((1ULL << (64 - ZAP_HASHBITS)) - 1);

        return crc;
}

/*
 * Only to be used on 8-bit arrays.
 * array_len is actual len in bytes (not encoded le_value_length).
 * buf is null-terminated.
 */
/* XXX */
static int
zap_leaf_array_equal(zap_leaf_phys_t *l, zfs_endian_t endian,
                                         int blksft, int chunk, int array_len, const char *buf)
{
        int bseen = 0;

        while (bseen < array_len) {
                struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(l, blksft, chunk).l_array;
                int toread = min(array_len - bseen, ZAP_LEAF_ARRAY_BYTES);

                if (chunk >= ZAP_LEAF_NUMCHUNKS(blksft))
                        return 0;

                if (memcmp(la->la_array, buf + bseen, toread) != 0)
                        break;
                chunk = zfs_to_cpu16(la->la_next, endian);
                bseen += toread;
        }
        return (bseen == array_len);
}

/* XXX */
static int
zap_leaf_array_get(zap_leaf_phys_t *l, zfs_endian_t endian, int blksft,
                                   int chunk, int array_len, char *buf)
{
        int bseen = 0;

        while (bseen < array_len) {
                struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(l, blksft, chunk).l_array;
                int toread = min(array_len - bseen, ZAP_LEAF_ARRAY_BYTES);

                if (chunk >= ZAP_LEAF_NUMCHUNKS(blksft))
                        /* Don't use errno because this error is to be ignored.  */
                        return ZFS_ERR_BAD_FS;

                memcpy(buf + bseen, la->la_array,  toread);
                chunk = zfs_to_cpu16(la->la_next, endian);
                bseen += toread;
        }
        return ZFS_ERR_NONE;
}


/*
 * Given a zap_leaf_phys_t, walk thru the zap leaf chunks to get the
 * value for the property "name".
 *
 */
/* XXX */
static int
zap_leaf_lookup(zap_leaf_phys_t *l, zfs_endian_t endian,
                                int blksft, uint64_t h,
                                const char *name, uint64_t *value)
{
        uint16_t chunk;
        struct zap_leaf_entry *le;

        /* Verify if this is a valid leaf block */
        if (zfs_to_cpu64(l->l_hdr.lh_block_type, endian) != ZBT_LEAF) {
                printf("invalid leaf type\n");
                return ZFS_ERR_BAD_FS;
        }
        if (zfs_to_cpu32(l->l_hdr.lh_magic, endian) != ZAP_LEAF_MAGIC) {
                printf("invalid leaf magic\n");
                return ZFS_ERR_BAD_FS;
        }

        for (chunk = zfs_to_cpu16(l->l_hash[LEAF_HASH(blksft, h)], endian);
                 chunk != CHAIN_END; chunk = le->le_next) {

                if (chunk >= ZAP_LEAF_NUMCHUNKS(blksft)) {
                        printf("invalid chunk number\n");
                        return ZFS_ERR_BAD_FS;
                }

                le = ZAP_LEAF_ENTRY(l, blksft, chunk);

                /* Verify the chunk entry */
                if (le->le_type != ZAP_CHUNK_ENTRY) {
                        printf("invalid chunk entry\n");
                        return ZFS_ERR_BAD_FS;
                }

                if (zfs_to_cpu64(le->le_hash, endian) != h)
                        continue;

                if (zap_leaf_array_equal(l, endian, blksft,
                                                                 zfs_to_cpu16(le->le_name_chunk, endian),
                                                                 zfs_to_cpu16(le->le_name_length, endian),
                                                                 name)) {
                        struct zap_leaf_array *la;

                        if (le->le_int_size != 8 || le->le_value_length != 1) {
                                printf("invalid leaf chunk entry\n");
                                return ZFS_ERR_BAD_FS;
                        }
                        /* get the uint64_t property value */
                        la = &ZAP_LEAF_CHUNK(l, blksft, le->le_value_chunk).l_array;

                        *value = be64_to_cpu(la->la_array64);

                        return ZFS_ERR_NONE;
                }
        }

        printf("couldn't find '%s'\n", name);
        return ZFS_ERR_FILE_NOT_FOUND;
}


/* Verify if this is a fat zap header block */
static int
zap_verify(zap_phys_t *zap)
{
        if (zap->zap_magic != (uint64_t) ZAP_MAGIC) {
                printf("bad ZAP magic\n");
                return ZFS_ERR_BAD_FS;
        }

        if (zap->zap_flags != 0) {
                printf("bad ZAP flags\n");
                return ZFS_ERR_BAD_FS;
        }

        if (zap->zap_salt == 0) {
                printf("bad ZAP salt\n");
                return ZFS_ERR_BAD_FS;
        }

        return ZFS_ERR_NONE;
}

/*
 * Fat ZAP lookup
 *
 */
/* XXX */
static int
fzap_lookup(dnode_end_t *zap_dnode, zap_phys_t *zap,
                        char *name, uint64_t *value, struct zfs_data *data)
{
        void *l;
        uint64_t hash, idx, blkid;
        int blksft = zfs_log2(zfs_to_cpu16(zap_dnode->dn.dn_datablkszsec,
                                                                                        zap_dnode->endian) << DNODE_SHIFT);
        int err;
        zfs_endian_t leafendian;

        err = zap_verify(zap);
        if (err)
                return err;

        hash = zap_hash(zap->zap_salt, name);

        /* get block id from index */
        if (zap->zap_ptrtbl.zt_numblks != 0) {
                printf("external pointer tables not supported\n");
                return ZFS_ERR_NOT_IMPLEMENTED_YET;
        }
        idx = ZAP_HASH_IDX(hash, zap->zap_ptrtbl.zt_shift);
        blkid = ((uint64_t *) zap)[idx + (1 << (blksft - 3 - 1))];

        /* Get the leaf block */
        if ((1U << blksft) < sizeof(zap_leaf_phys_t)) {
                printf("ZAP leaf is too small\n");
                return ZFS_ERR_BAD_FS;
        }
        err = dmu_read(zap_dnode, blkid, &l, &leafendian, data);
        if (err)
                return err;

        err = zap_leaf_lookup(l, leafendian, blksft, hash, name, value);
        free(l);
        return err;
}

/* XXX */
static int
fzap_iterate(dnode_end_t *zap_dnode, zap_phys_t *zap,
                         int (*hook)(const char *name,
                                                 uint64_t val,
                                                 struct zfs_data *data),
                         struct zfs_data *data)
{
        zap_leaf_phys_t *l;
        void *l_in;
        uint64_t idx, blkid;
        uint16_t chunk;
        int blksft = zfs_log2(zfs_to_cpu16(zap_dnode->dn.dn_datablkszsec,
                                                                                        zap_dnode->endian) << DNODE_SHIFT);
        int err;
        zfs_endian_t endian;

        if (zap_verify(zap))
                return 0;

        /* get block id from index */
        if (zap->zap_ptrtbl.zt_numblks != 0) {
                printf("external pointer tables not supported\n");
                return 0;
        }
        /* Get the leaf block */
        if ((1U << blksft) < sizeof(zap_leaf_phys_t)) {
                printf("ZAP leaf is too small\n");
                return 0;
        }
        for (idx = 0; idx < zap->zap_ptrtbl.zt_numblks; idx++) {
                blkid = ((uint64_t *) zap)[idx + (1 << (blksft - 3 - 1))];

                err = dmu_read(zap_dnode, blkid, &l_in, &endian, data);
                l = l_in;
                if (err)
                        continue;

                /* Verify if this is a valid leaf block */
                if (zfs_to_cpu64(l->l_hdr.lh_block_type, endian) != ZBT_LEAF) {
                        free(l);
                        continue;
                }
                if (zfs_to_cpu32(l->l_hdr.lh_magic, endian) != ZAP_LEAF_MAGIC) {
                        free(l);
                        continue;
                }

                for (chunk = 0; chunk < ZAP_LEAF_NUMCHUNKS(blksft); chunk++) {
                        char *buf;
                        struct zap_leaf_array *la;
                        struct zap_leaf_entry *le;
                        uint64_t val;
                        le = ZAP_LEAF_ENTRY(l, blksft, chunk);

                        /* Verify the chunk entry */
                        if (le->le_type != ZAP_CHUNK_ENTRY)

                                continue;

                        buf = malloc(zfs_to_cpu16(le->le_name_length, endian)
                                                 + 1);
                        if (zap_leaf_array_get(l, endian, blksft, le->le_name_chunk,
                                                                   le->le_name_length, buf)) {
                                free(buf);
                                continue;
                        }
                        buf[le->le_name_length] = 0;

                        if (le->le_int_size != 8
                                || zfs_to_cpu16(le->le_value_length, endian) != 1)
                                continue;

                        /* get the uint64_t property value */
                        la = &ZAP_LEAF_CHUNK(l, blksft, le->le_value_chunk).l_array;
                        val = be64_to_cpu(la->la_array64);
                        if (hook(buf, val, data))
                                return 1;
                        free(buf);
                }
        }
        return 0;
}


/*
 * Read in the data of a zap object and find the value for a matching
 * property name.
 *
 */
static int
zap_lookup(dnode_end_t *zap_dnode, char *name, uint64_t *val,
                   struct zfs_data *data)
{
        uint64_t block_type;
        int size;
        void *zapbuf;
        int err;
        zfs_endian_t endian;

        /* Read in the first block of the zap object data. */
        size = zfs_to_cpu16(zap_dnode->dn.dn_datablkszsec,
                                                         zap_dnode->endian) << SPA_MINBLOCKSHIFT;
        err = dmu_read(zap_dnode, 0, &zapbuf, &endian, data);
        if (err)
                return err;
        block_type = zfs_to_cpu64(*((uint64_t *) zapbuf), endian);

        if (block_type == ZBT_MICRO) {
                err = (mzap_lookup(zapbuf, endian, size, name, val));
                free(zapbuf);
                return err;
        } else if (block_type == ZBT_HEADER) {
                /* this is a fat zap */
                err = (fzap_lookup(zap_dnode, zapbuf, name, val, data));
                free(zapbuf);
                return err;
        }

        printf("unknown ZAP type\n");
        free(zapbuf);
        return ZFS_ERR_BAD_FS;
}

static int
zap_iterate(dnode_end_t *zap_dnode,
                        int (*hook)(const char *name, uint64_t val,
                                                struct zfs_data *data),
                        struct zfs_data *data)
{
        uint64_t block_type;
        int size;
        void *zapbuf;
        int err;
        int ret;
        zfs_endian_t endian;

        /* Read in the first block of the zap object data. */
        size = zfs_to_cpu16(zap_dnode->dn.dn_datablkszsec, zap_dnode->endian) << SPA_MINBLOCKSHIFT;
        err = dmu_read(zap_dnode, 0, &zapbuf, &endian, data);
        if (err)
                return 0;
        block_type = zfs_to_cpu64(*((uint64_t *) zapbuf), endian);

        if (block_type == ZBT_MICRO) {
                ret = mzap_iterate(zapbuf, endian, size, hook, data);
                free(zapbuf);
                return ret;
        } else if (block_type == ZBT_HEADER) {
                /* this is a fat zap */
                ret = fzap_iterate(zap_dnode, zapbuf, hook, data);
                free(zapbuf);
                return ret;
        }
        printf("unknown ZAP type\n");
        free(zapbuf);
        return 0;
}


/*
 * Get the dnode of an object number from the metadnode of an object set.
 *
 * Input
 *      mdn - metadnode to get the object dnode
 *      objnum - object number for the object dnode
 *      buf - data buffer that holds the returning dnode
 */
static int
dnode_get(dnode_end_t *mdn, uint64_t objnum, uint8_t type,
                  dnode_end_t *buf, struct zfs_data *data)
{
        uint64_t blkid, blksz;  /* the block id this object dnode is in */
        int epbs;                       /* shift of number of dnodes in a block */
        int idx;                        /* index within a block */
        void *dnbuf;
        int err;
        zfs_endian_t endian;

        blksz = zfs_to_cpu16(mdn->dn.dn_datablkszsec,
                                                          mdn->endian) << SPA_MINBLOCKSHIFT;

        epbs = zfs_log2(blksz) - DNODE_SHIFT;
        blkid = objnum >> epbs;
        idx = objnum & ((1 << epbs) - 1);

        if (data->dnode_buf != NULL && memcmp(data->dnode_mdn, mdn,
                                                                                  sizeof(*mdn)) == 0
                && objnum >= data->dnode_start && objnum < data->dnode_end) {
                memmove(&(buf->dn), &(data->dnode_buf)[idx], DNODE_SIZE);
                buf->endian = data->dnode_endian;
                if (type && buf->dn.dn_type != type)  {
                        printf("incorrect dnode type: %02X != %02x\n", buf->dn.dn_type, type);
                        return ZFS_ERR_BAD_FS;
                }
                return ZFS_ERR_NONE;
        }

        err = dmu_read(mdn, blkid, &dnbuf, &endian, data);
        if (err)
                return err;

        free(data->dnode_buf);
        free(data->dnode_mdn);
        data->dnode_mdn = malloc(sizeof(*mdn));
        if (!data->dnode_mdn) {
                data->dnode_buf = 0;
        } else {
                memcpy(data->dnode_mdn, mdn, sizeof(*mdn));
                data->dnode_buf = dnbuf;
                data->dnode_start = blkid << epbs;
                data->dnode_end = (blkid + 1) << epbs;
                data->dnode_endian = endian;
        }

        memmove(&(buf->dn), (dnode_phys_t *) dnbuf + idx, DNODE_SIZE);
        buf->endian = endian;
        if (type && buf->dn.dn_type != type) {
                printf("incorrect dnode type\n");
                return ZFS_ERR_BAD_FS;
        }

        return ZFS_ERR_NONE;
}

/*
 * Get the file dnode for a given file name where mdn is the meta dnode
 * for this ZFS object set. When found, place the file dnode in dn.
 * The 'path' argument will be mangled.
 *
 */
static int
dnode_get_path(dnode_end_t *mdn, const char *path_in, dnode_end_t *dn,
                           struct zfs_data *data)
{
        uint64_t objnum, version;
        char *cname, ch;
        int err = ZFS_ERR_NONE;
        char *path, *path_buf;
        struct dnode_chain {
                struct dnode_chain *next;
                dnode_end_t dn;
        };
        struct dnode_chain *dnode_path = 0, *dn_new, *root;

        dn_new = malloc(sizeof(*dn_new));
        if (!dn_new)
                return ZFS_ERR_OUT_OF_MEMORY;
        dn_new->next = 0;
        dnode_path = root = dn_new;

        err = dnode_get(mdn, MASTER_NODE_OBJ, DMU_OT_MASTER_NODE,
                                        &(dnode_path->dn), data);
        if (err) {
                free(dn_new);
                return err;
        }

        err = zap_lookup(&(dnode_path->dn), ZPL_VERSION_STR, &version, data);
        if (err) {
                free(dn_new);
                return err;
        }
        if (version > ZPL_VERSION) {
                free(dn_new);
                printf("too new ZPL version\n");
                return ZFS_ERR_NOT_IMPLEMENTED_YET;
        }

        err = zap_lookup(&(dnode_path->dn), ZFS_ROOT_OBJ, &objnum, data);
        if (err) {
                free(dn_new);
                return err;
        }

        err = dnode_get(mdn, objnum, 0, &(dnode_path->dn), data);
        if (err) {
                free(dn_new);
                return err;
        }

        path = path_buf = strdup(path_in);
        if (!path_buf) {
                free(dn_new);
                return ZFS_ERR_OUT_OF_MEMORY;
        }

        while (1) {
                /* skip leading slashes */
                while (*path == '/')
                        path++;
                if (!*path)
                        break;
                /* get the next component name */
                cname = path;
                while (*path && *path != '/')
                        path++;
                /* Skip dot.  */
                if (cname + 1 == path && cname[0] == '.')
                        continue;
                /* Handle double dot.  */
                if (cname + 2 == path && cname[0] == '.' && cname[1] == '.')  {
                        if (dn_new->next) {
                                dn_new = dnode_path;
                                dnode_path = dn_new->next;
                                free(dn_new);
                        } else {
                                printf("can't resolve ..\n");
                                err = ZFS_ERR_FILE_NOT_FOUND;
                                break;
                        }
                        continue;
                }

                ch = *path;
                *path = 0;              /* ensure null termination */

                if (dnode_path->dn.dn.dn_type != DMU_OT_DIRECTORY_CONTENTS) {
                        free(path_buf);
                        printf("not a directory\n");
                        return ZFS_ERR_BAD_FILE_TYPE;
                }
                err = zap_lookup(&(dnode_path->dn), cname, &objnum, data);
                if (err)
                        break;

                dn_new = malloc(sizeof(*dn_new));
                if (!dn_new) {
                        err = ZFS_ERR_OUT_OF_MEMORY;
                        break;
                }
                dn_new->next = dnode_path;
                dnode_path = dn_new;

                objnum = ZFS_DIRENT_OBJ(objnum);
                err = dnode_get(mdn, objnum, 0, &(dnode_path->dn), data);
                if (err)
                        break;

                *path = ch;
        }

        if (!err)
                memcpy(dn, &(dnode_path->dn), sizeof(*dn));

        while (dnode_path) {
                dn_new = dnode_path->next;
                free(dnode_path);
                dnode_path = dn_new;
        }
        free(path_buf);
        return err;
}


/*
 * Given a MOS metadnode, get the metadnode of a given filesystem name (fsname),
 * e.g. pool/rootfs, or a given object number (obj), e.g. the object number
 * of pool/rootfs.
 *
 * If no fsname and no obj are given, return the DSL_DIR metadnode.
 * If fsname is given, return its metadnode and its matching object number.
 * If only obj is given, return the metadnode for this object number.
 *
 */
static int
get_filesystem_dnode(dnode_end_t *mosmdn, char *fsname,
                                         dnode_end_t *mdn, struct zfs_data *data)
{
        uint64_t objnum;
        int err;

        err = dnode_get(mosmdn, DMU_POOL_DIRECTORY_OBJECT,
                                        DMU_OT_OBJECT_DIRECTORY, mdn, data);
        if (err)
                return err;

        err = zap_lookup(mdn, DMU_POOL_ROOT_DATASET, &objnum, data);
        if (err)
                return err;

        err = dnode_get(mosmdn, objnum, DMU_OT_DSL_DIR, mdn, data);
        if (err)
                return err;

        while (*fsname) {
                uint64_t childobj;
                char *cname, ch;

                while (*fsname == '/')
                        fsname++;

                if (!*fsname || *fsname == '@')
                        break;

                cname = fsname;
                while (*fsname && !isspace(*fsname) && *fsname != '/')
                        fsname++;
                ch = *fsname;
                *fsname = 0;

                childobj = zfs_to_cpu64((((dsl_dir_phys_t *) DN_BONUS(&mdn->dn)))->dd_child_dir_zapobj, mdn->endian);
                err = dnode_get(mosmdn, childobj,
                                                DMU_OT_DSL_DIR_CHILD_MAP, mdn, data);
                if (err)
                        return err;

                err = zap_lookup(mdn, cname, &objnum, data);
                if (err)
                        return err;

                err = dnode_get(mosmdn, objnum, DMU_OT_DSL_DIR, mdn, data);
                if (err)
                        return err;

                *fsname = ch;
        }
        return ZFS_ERR_NONE;
}

static int
make_mdn(dnode_end_t *mdn, struct zfs_data *data)
{
        void *osp;
        blkptr_t *bp;
        size_t ospsize;
        int err;

        bp = &(((dsl_dataset_phys_t *) DN_BONUS(&mdn->dn))->ds_bp);
        err = zio_read(bp, mdn->endian, &osp, &ospsize, data);
        if (err)
                return err;
        if (ospsize < OBJSET_PHYS_SIZE_V14) {
                free(osp);
                printf("too small osp\n");
                return ZFS_ERR_BAD_FS;
        }

        mdn->endian = (zfs_to_cpu64(bp->blk_prop, mdn->endian)>>63) & 1;
        memmove((char *) &(mdn->dn),
                        (char *) &((objset_phys_t *) osp)->os_meta_dnode, DNODE_SIZE);
        free(osp);
        return ZFS_ERR_NONE;
}

static int
dnode_get_fullpath(const char *fullpath, dnode_end_t *mdn,
                                   uint64_t *mdnobj, dnode_end_t *dn, int *isfs,
                                   struct zfs_data *data)
{
        char *fsname, *snapname;
        const char *ptr_at, *filename;
        uint64_t headobj;
        int err;

        ptr_at = strchr(fullpath, '@');
        if (!ptr_at) {
                *isfs = 1;
                filename = 0;
                snapname = 0;
                fsname = strdup(fullpath);
        } else {
                const char *ptr_slash = strchr(ptr_at, '/');

                *isfs = 0;
                fsname = malloc(ptr_at - fullpath + 1);
                if (!fsname)
                        return ZFS_ERR_OUT_OF_MEMORY;
                memcpy(fsname, fullpath, ptr_at - fullpath);
                fsname[ptr_at - fullpath] = 0;
                if (ptr_at[1] && ptr_at[1] != '/') {
                        snapname = malloc(ptr_slash - ptr_at);
                        if (!snapname) {
                                free(fsname);
                                return ZFS_ERR_OUT_OF_MEMORY;
                        }
                        memcpy(snapname, ptr_at + 1, ptr_slash - ptr_at - 1);
                        snapname[ptr_slash - ptr_at - 1] = 0;
                } else {
                        snapname = 0;
                }
                if (ptr_slash)
                        filename = ptr_slash;
                else
                        filename = "/";
                printf("zfs fsname = '%s' snapname='%s' filename = '%s'\n",
                           fsname, snapname, filename);
        }


        err = get_filesystem_dnode(&(data->mos), fsname, dn, data);

        if (err) {
                free(fsname);
                free(snapname);
                return err;
        }

        headobj = zfs_to_cpu64(((dsl_dir_phys_t *) DN_BONUS(&dn->dn))->dd_head_dataset_obj, dn->endian);

        err = dnode_get(&(data->mos), headobj, DMU_OT_DSL_DATASET, mdn, data);
        if (err) {
                free(fsname);
                free(snapname);
                return err;
        }

        if (snapname) {
                uint64_t snapobj;

                snapobj = zfs_to_cpu64(((dsl_dataset_phys_t *) DN_BONUS(&mdn->dn))->ds_snapnames_zapobj, mdn->endian);

                err = dnode_get(&(data->mos), snapobj,
                                                DMU_OT_DSL_DS_SNAP_MAP, mdn, data);
                if (!err)
                        err = zap_lookup(mdn, snapname, &headobj, data);
                if (!err)
                        err = dnode_get(&(data->mos), headobj, DMU_OT_DSL_DATASET, mdn, data);
                if (err) {
                        free(fsname);
                        free(snapname);
                        return err;
                }
        }

        if (mdnobj)
                *mdnobj = headobj;

        make_mdn(mdn, data);

        if (*isfs) {
                free(fsname);
                free(snapname);
                return ZFS_ERR_NONE;
        }
        err = dnode_get_path(mdn, filename, dn, data);
        free(fsname);
        free(snapname);
        return err;
}

/*
 * For a given XDR packed nvlist, verify the first 4 bytes and move on.
 *
 * An XDR packed nvlist is encoded as (comments from nvs_xdr_create) :
 *
 *              encoding method/host endian             (4 bytes)
 *              nvl_version                                             (4 bytes)
 *              nvl_nvflag                                              (4 bytes)
 *      encoded nvpairs:
 *              encoded size of the nvpair              (4 bytes)
 *              decoded size of the nvpair              (4 bytes)
 *              name string size                                (4 bytes)
 *              name string data                                (sizeof(NV_ALIGN4(string))
 *              data type                                               (4 bytes)
 *              # of elements in the nvpair             (4 bytes)
 *              data
 *              2 zero's for the last nvpair
 *              (end of the entire list)        (8 bytes)
 *
 */

static int
nvlist_find_value(char *nvlist, char *name, int valtype, char **val,
                                  size_t *size_out, size_t *nelm_out)
{
        int name_len, type, encode_size;
        char *nvpair, *nvp_name;

        /* Verify if the 1st and 2nd byte in the nvlist are valid. */
        /* NOTE: independently of what endianness header announces all
           subsequent values are big-endian.  */
        if (nvlist[0] != NV_ENCODE_XDR || (nvlist[1] != NV_LITTLE_ENDIAN
                                                                           && nvlist[1] != NV_BIG_ENDIAN)) {
                printf("zfs incorrect nvlist header\n");
                return ZFS_ERR_BAD_FS;
        }

        /* skip the header, nvl_version, and nvl_nvflag */
        nvlist = nvlist + 4 * 3;
        /*
         * Loop thru the nvpair list
         * The XDR representation of an integer is in big-endian byte order.
         */
        while ((encode_size = be32_to_cpu(*(uint32_t *) nvlist))) {
                int nelm;

                nvpair = nvlist + 4 * 2;        /* skip the encode/decode size */

                name_len = be32_to_cpu(*(uint32_t *) nvpair);
                nvpair += 4;

                nvp_name = nvpair;
                nvpair = nvpair + ((name_len + 3) & ~3);        /* align */

                type = be32_to_cpu(*(uint32_t *) nvpair);
                nvpair += 4;

                nelm = be32_to_cpu(*(uint32_t *) nvpair);
                if (nelm < 1) {
                        printf("empty nvpair\n");
                        return ZFS_ERR_BAD_FS;
                }

                nvpair += 4;

                if ((strncmp(nvp_name, name, name_len) == 0) && type == valtype) {
                        *val = nvpair;
                        *size_out = encode_size;
                        if (nelm_out)
                                *nelm_out = nelm;
                        return 1;
                }

                nvlist += encode_size;  /* goto the next nvpair */
        }
        return 0;
}

int
zfs_nvlist_lookup_uint64(char *nvlist, char *name, uint64_t *out)
{
        char *nvpair;
        size_t size;
        int found;

        found = nvlist_find_value(nvlist, name, DATA_TYPE_UINT64, &nvpair, &size, 0);
        if (!found)
                return 0;
        if (size < sizeof(uint64_t)) {
                printf("invalid uint64\n");
                return ZFS_ERR_BAD_FS;
        }

        *out = be64_to_cpu(*(uint64_t *) nvpair);
        return 1;
}

char *
zfs_nvlist_lookup_string(char *nvlist, char *name)
{
        char *nvpair;
        char *ret;
        size_t slen;
        size_t size;
        int found;

        found = nvlist_find_value(nvlist, name, DATA_TYPE_STRING, &nvpair, &size, 0);
        if (!found)
                return 0;
        if (size < 4) {
                printf("invalid string\n");
                return 0;
        }
        slen = be32_to_cpu(*(uint32_t *) nvpair);
        if (slen > size - 4)
                slen = size - 4;
        ret = malloc(slen + 1);
        if (!ret)
                return 0;
        memcpy(ret, nvpair + 4, slen);
        ret[slen] = 0;
        return ret;
}

char *
zfs_nvlist_lookup_nvlist(char *nvlist, char *name)
{
        char *nvpair;
        char *ret;
        size_t size;
        int found;

        found = nvlist_find_value(nvlist, name, DATA_TYPE_NVLIST, &nvpair,
                                                          &size, 0);
        if (!found)
                return 0;
        ret = calloc(1, size + 3 * sizeof(uint32_t));
        if (!ret)
                return 0;
        memcpy(ret, nvlist, sizeof(uint32_t));

        memcpy(ret + sizeof(uint32_t), nvpair, size);
        return ret;
}

int
zfs_nvlist_lookup_nvlist_array_get_nelm(char *nvlist, char *name)
{
        char *nvpair;
        size_t nelm, size;
        int found;

        found = nvlist_find_value(nvlist, name, DATA_TYPE_NVLIST, &nvpair,
                                                          &size, &nelm);
        if (!found)
                return -1;
        return nelm;
}

char *
zfs_nvlist_lookup_nvlist_array(char *nvlist, char *name,
                                                                        size_t index)
{
        char *nvpair, *nvpairptr;
        int found;
        char *ret;
        size_t size;
        unsigned i;
        size_t nelm;

        found = nvlist_find_value(nvlist, name, DATA_TYPE_NVLIST, &nvpair,
                                                          &size, &nelm);
        if (!found)
                return 0;
        if (index >= nelm) {
                printf("trying to lookup past nvlist array\n");
                return 0;
        }

        nvpairptr = nvpair;

        for (i = 0; i < index; i++) {
                uint32_t encode_size;

                /* skip the header, nvl_version, and nvl_nvflag */
                nvpairptr = nvpairptr + 4 * 2;

                while (nvpairptr < nvpair + size
                           && (encode_size = be32_to_cpu(*(uint32_t *) nvpairptr)))
                        nvlist += encode_size;  /* goto the next nvpair */

                nvlist = nvlist + 4 * 2;        /* skip the ending 2 zeros - 8 bytes */
        }

        if (nvpairptr >= nvpair + size
                || nvpairptr + be32_to_cpu(*(uint32_t *) (nvpairptr + 4 * 2))
                >= nvpair + size) {
                printf("incorrect nvlist array\n");
                return 0;
        }

        ret = calloc(1, be32_to_cpu(*(uint32_t *) (nvpairptr + 4 * 2))
                                 + 3 * sizeof(uint32_t));
        if (!ret)
                return 0;
        memcpy(ret, nvlist, sizeof(uint32_t));

        memcpy(ret + sizeof(uint32_t), nvpairptr, size);
        return ret;
}

static int
int_zfs_fetch_nvlist(struct zfs_data *data, char **nvlist)
{
        int err;

        *nvlist = malloc(VDEV_PHYS_SIZE);
        /* Read in the vdev name-value pair list (112K). */
        err = zfs_devread(data->vdev_phys_sector, 0, VDEV_PHYS_SIZE, *nvlist);
        if (err) {
                free(*nvlist);
                *nvlist = 0;
                return err;
        }
        return ZFS_ERR_NONE;
}

/*
 * Check the disk label information and retrieve needed vdev name-value pairs.
 *
 */
static int
check_pool_label(struct zfs_data *data)
{
        uint64_t pool_state;
        char *nvlist;                   /* for the pool */
        char *vdevnvlist;               /* for the vdev */
        uint64_t diskguid;
        uint64_t version;
        int found;
        int err;

        err = int_zfs_fetch_nvlist(data, &nvlist);
        if (err)
                return err;

        found = zfs_nvlist_lookup_uint64(nvlist, ZPOOL_CONFIG_POOL_STATE,
                                                                                  &pool_state);
        if (!found) {
                free(nvlist);
                printf("zfs pool state not found\n");
                return ZFS_ERR_BAD_FS;
        }

        if (pool_state == POOL_STATE_DESTROYED) {
                free(nvlist);
                printf("zpool is marked as destroyed\n");
                return ZFS_ERR_BAD_FS;
        }

        data->label_txg = 0;
        found = zfs_nvlist_lookup_uint64(nvlist, ZPOOL_CONFIG_POOL_TXG,
                                                                                  &data->label_txg);
        if (!found) {
                free(nvlist);
                printf("zfs pool txg not found\n");
                return ZFS_ERR_BAD_FS;
        }

        /* not an active device */
        if (data->label_txg == 0) {
                free(nvlist);
                printf("zpool is not active\n");
                return ZFS_ERR_BAD_FS;
        }

        found = zfs_nvlist_lookup_uint64(nvlist, ZPOOL_CONFIG_VERSION,
                                                                                  &version);
        if (!found) {
                free(nvlist);
                printf("zpool config version not found\n");
                return ZFS_ERR_BAD_FS;
        }

        if (version > SPA_VERSION) {
                free(nvlist);
                printf("SPA version too new %llu > %llu\n",
                           (unsigned long long) version,
                           (unsigned long long) SPA_VERSION);
                return ZFS_ERR_NOT_IMPLEMENTED_YET;
        }

        vdevnvlist = zfs_nvlist_lookup_nvlist(nvlist, ZPOOL_CONFIG_VDEV_TREE);
        if (!vdevnvlist) {
                free(nvlist);
                printf("ZFS config vdev tree not found\n");
                return ZFS_ERR_BAD_FS;
        }

        found = zfs_nvlist_lookup_uint64(vdevnvlist, ZPOOL_CONFIG_ASHIFT,
                                                                                  &data->vdev_ashift);
        free(vdevnvlist);
        if (!found) {
                free(nvlist);
                printf("ZPOOL config ashift not found\n");
                return ZFS_ERR_BAD_FS;
        }

        found = zfs_nvlist_lookup_uint64(nvlist, ZPOOL_CONFIG_GUID, &diskguid);
        if (!found) {
                free(nvlist);
                printf("ZPOOL config guid not found\n");
                return ZFS_ERR_BAD_FS;
        }

        found = zfs_nvlist_lookup_uint64(nvlist, ZPOOL_CONFIG_POOL_GUID, &data->pool_guid);
        if (!found) {
                free(nvlist);
                printf("ZPOOL config pool guid not found\n");
                return ZFS_ERR_BAD_FS;
        }

        free(nvlist);

        printf("ZFS Pool GUID: %llu (%016llx) Label: GUID: %llu (%016llx), txg: %llu, SPA v%llu, ashift: %llu\n",
                   (unsigned long long) data->pool_guid,
                   (unsigned long long) data->pool_guid,
                   (unsigned long long) diskguid,
                   (unsigned long long) diskguid,
                   (unsigned long long) data->label_txg,
                   (unsigned long long) version,
                   (unsigned long long) data->vdev_ashift);

        return ZFS_ERR_NONE;
}

/*
 * vdev_label_start returns the physical disk offset (in bytes) of
 * label "l".
 */
static uint64_t vdev_label_start(uint64_t psize, int l)
{
        return (l * sizeof(vdev_label_t) + (l < VDEV_LABELS / 2 ?
                                                                                0 : psize -
                                                                                VDEV_LABELS * sizeof(vdev_label_t)));
}

void
zfs_unmount(struct zfs_data *data)
{
        free(data->dnode_buf);
        free(data->dnode_mdn);
        free(data->file_buf);
        free(data);
}

/*
 * zfs_mount() locates a valid uberblock of the root pool and read in its MOS
 * to the memory address MOS.
 *
 */
struct zfs_data *
zfs_mount(device_t dev)
{
        struct zfs_data *data = 0;
        int label = 0, bestlabel = -1;
        char *ub_array;
        uberblock_t *ubbest;
        uberblock_t *ubcur = NULL;
        void *osp = 0;
        size_t ospsize;
        int err;

        data = malloc(sizeof(*data));
        if (!data)
                return 0;
        memset(data, 0, sizeof(*data));

        ub_array = malloc(VDEV_UBERBLOCK_RING);
        if (!ub_array) {
                zfs_unmount(data);
                return 0;
        }

        ubbest = malloc(sizeof(*ubbest));
        if (!ubbest) {
                free(ub_array);
                zfs_unmount(data);
                return 0;
        }
        memset(ubbest, 0, sizeof(*ubbest));

        /*
         * some eltorito stacks don't give us a size and
         * we end up setting the size to MAXUINT, further
         * some of these devices stop working once a single
         * read past the end has been issued. Checking
         * for a maximum part_length and skipping the backup
         * labels at the end of the slice/partition/device
         * avoids breaking down on such devices.
         */
        const int vdevnum =
                dev->part_length == 0 ?
                VDEV_LABELS / 2 : VDEV_LABELS;

        /* Size in bytes of the device (disk or partition) aligned to label size*/
        uint64_t device_size =
                dev->part_length << SECTOR_BITS;

        const uint64_t alignedbytes =
                P2ALIGN(device_size, (uint64_t) sizeof(vdev_label_t));

        for (label = 0; label < vdevnum; label++) {
                uint64_t labelstartbytes = vdev_label_start(alignedbytes, label);
                uint64_t labelstart = labelstartbytes >> SECTOR_BITS;

                debug("zfs reading label %d at sector %llu (byte %llu)\n",
                          label, (unsigned long long) labelstart,
                          (unsigned long long) labelstartbytes);

                data->vdev_phys_sector = labelstart +
                        ((VDEV_SKIP_SIZE + VDEV_BOOT_HEADER_SIZE) >> SECTOR_BITS);

                err = check_pool_label(data);
                if (err) {
                        printf("zfs error checking label %d\n", label);
                        continue;
                }

                /* Read in the uberblock ring (128K). */
                err = zfs_devread(data->vdev_phys_sector  +
                                                  (VDEV_PHYS_SIZE >> SECTOR_BITS),
                                                  0, VDEV_UBERBLOCK_RING, ub_array);
                if (err) {
                        printf("zfs error reading uberblock ring for label %d\n", label);
                        continue;
                }

                ubcur = find_bestub(ub_array, data);
                if (!ubcur) {
                        printf("zfs No good uberblocks found in label %d\n", label);
                        continue;
                }

                if (vdev_uberblock_compare(ubcur, ubbest) > 0) {
                        /* Looks like the block is good, so use it.*/
                        memcpy(ubbest, ubcur, sizeof(*ubbest));
                        bestlabel = label;
                        debug("zfs Current best uberblock found in label %d\n", label);
                }
        }
        free(ub_array);

        /* We zero'd the structure to begin with.  If we never assigned to it,
           magic will still be zero. */
        if (!ubbest->ub_magic) {
                printf("couldn't find a valid ZFS label\n");
                zfs_unmount(data);
                free(ubbest);
                return 0;
        }

        debug("zfs ubbest %p in label %d\n", ubbest, bestlabel);

        zfs_endian_t ub_endian =
                zfs_to_cpu64(ubbest->ub_magic, LITTLE_ENDIAN) == UBERBLOCK_MAGIC
                ? LITTLE_ENDIAN : BIG_ENDIAN;

        debug("zfs endian set to %s\n", !ub_endian ? "big" : "little");

        err = zio_read(&ubbest->ub_rootbp, ub_endian, &osp, &ospsize, data);

        if (err) {
                printf("couldn't zio_read object directory\n");
                zfs_unmount(data);
                free(osp);
                free(ubbest);
                return 0;
        }

        if (ospsize < OBJSET_PHYS_SIZE_V14) {
                printf("osp too small\n");
                zfs_unmount(data);
                free(osp);
                free(ubbest);
                return 0;
        }

        /* Got the MOS. Save it at the memory addr MOS. */
        memmove(&(data->mos.dn), &((objset_phys_t *) osp)->os_meta_dnode, DNODE_SIZE);
        data->mos.endian =
                (zfs_to_cpu64(ubbest->ub_rootbp.blk_prop, ub_endian) >> 63) & 1;
        memmove(&(data->current_uberblock), ubbest, sizeof(uberblock_t));

        free(osp);
        free(ubbest);

        return data;
}

int
zfs_fetch_nvlist(device_t dev, char **nvlist)
{
        struct zfs_data *zfs;
        int err;

        zfs = zfs_mount(dev);
        if (!zfs)
                return ZFS_ERR_BAD_FS;
        err = int_zfs_fetch_nvlist(zfs, nvlist);
        zfs_unmount(zfs);
        return err;
}

/*
 * zfs_open() locates a file in the rootpool by following the
 * MOS and places the dnode of the file in the memory address DNODE.

 */
int
zfs_open(struct zfs_file *file, const char *fsfilename)
{
        struct zfs_data *data;
        int err;
        int isfs;

        data = zfs_mount(file->device);
        if (!data)
                return ZFS_ERR_BAD_FS;

        err = dnode_get_fullpath(fsfilename, &(data->mdn), 0,
                                                         &(data->dnode), &isfs, data);
        if (err) {
                zfs_unmount(data);
                return err;
        }

        if (isfs) {
                zfs_unmount(data);
                printf("Missing @ or / separator\n");
                return ZFS_ERR_FILE_NOT_FOUND;
        }

        /* We found the dnode for this file. Verify if it is a plain file. */
        if (data->dnode.dn.dn_type != DMU_OT_PLAIN_FILE_CONTENTS) {
                zfs_unmount(data);
                printf("not a file\n");
                return ZFS_ERR_BAD_FILE_TYPE;
        }

        /* get the file size and set the file position to 0 */

        /*
         * For DMU_OT_SA we will need to locate the SIZE attribute
         * attribute, which could be either in the bonus buffer
         * or the "spill" block.
         */
        if (data->dnode.dn.dn_bonustype == DMU_OT_SA) {
                void *sahdrp;
                int hdrsize;

                if (data->dnode.dn.dn_bonuslen != 0) {
                        sahdrp = (sa_hdr_phys_t *) DN_BONUS(&data->dnode.dn);
                } else if (data->dnode.dn.dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
                        blkptr_t *bp = &data->dnode.dn.dn_spill;

                        err = zio_read(bp, data->dnode.endian, &sahdrp, NULL, data);
                        if (err)
                                return err;
                } else {
                        printf("filesystem is corrupt :(\n");
                        return ZFS_ERR_BAD_FS;
                }

                hdrsize = SA_HDR_SIZE(((sa_hdr_phys_t *) sahdrp));
                file->size = *(uint64_t *) ((char *) sahdrp + hdrsize + SA_SIZE_OFFSET);
                if ((data->dnode.dn.dn_bonuslen == 0) &&
                        (data->dnode.dn.dn_flags & DNODE_FLAG_SPILL_BLKPTR))
                        free(sahdrp);
        } else {
                file->size = zfs_to_cpu64(((znode_phys_t *) DN_BONUS(&data->dnode.dn))->zp_size, data->dnode.endian);
        }

        file->data = data;
        file->offset = 0;

        return ZFS_ERR_NONE;
}

uint64_t
zfs_read(zfs_file_t file, char *buf, uint64_t len)
{
        struct zfs_data *data = (struct zfs_data *) file->data;
        int blksz, movesize;
        uint64_t length;
        int64_t red;
        int err;

        if (data->file_buf == NULL) {
                data->file_buf = malloc(SPA_MAXBLOCKSIZE);
                if (!data->file_buf)
                        return -1;
                data->file_start = data->file_end = 0;
        }

        /*
         * If offset is in memory, move it into the buffer provided and return.
         */
        if (file->offset >= data->file_start
                && file->offset + len <= data->file_end) {
                memmove(buf, data->file_buf + file->offset - data->file_start,
                                len);
                return len;
        }

        blksz = zfs_to_cpu16(data->dnode.dn.dn_datablkszsec,
                                                          data->dnode.endian) << SPA_MINBLOCKSHIFT;

        /*
         * Entire Dnode is too big to fit into the space available.      We
         * will need to read it in chunks.      This could be optimized to
         * read in as large a chunk as there is space available, but for
         * now, this only reads in one data block at a time.
         */
        length = len;
        red = 0;
        while (length) {
                void *t;
                /*
                 * Find requested blkid and the offset within that block.
                 */
                uint64_t blkid = file->offset + red;
                blkid = do_div(blkid, blksz);
                free(data->file_buf);
                data->file_buf = 0;

                err = dmu_read(&(data->dnode), blkid, &t,
                                           0, data);
                data->file_buf = t;
                if (err)
                        return -1;

                data->file_start = blkid * blksz;
                data->file_end = data->file_start + blksz;

                movesize = min(length, data->file_end - (int)file->offset - red);

                memmove(buf, data->file_buf + file->offset + red
                                - data->file_start, movesize);
                buf += movesize;
                length -= movesize;
                red += movesize;
        }

        return len;
}

int
zfs_close(zfs_file_t file)
{
        zfs_unmount((struct zfs_data *) file->data);
        return ZFS_ERR_NONE;
}

int
zfs_getmdnobj(device_t dev, const char *fsfilename,
                                   uint64_t *mdnobj)
{
        struct zfs_data *data;
        int err;
        int isfs;

        data = zfs_mount(dev);
        if (!data)
                return ZFS_ERR_BAD_FS;

        err = dnode_get_fullpath(fsfilename, &(data->mdn), mdnobj,
                                                         &(data->dnode), &isfs, data);
        zfs_unmount(data);
        return err;
}

static void
fill_fs_info(struct zfs_dirhook_info *info,
                         dnode_end_t mdn, struct zfs_data *data)
{
        int err;
        dnode_end_t dn;
        uint64_t objnum;
        uint64_t headobj;

        memset(info, 0, sizeof(*info));

        info->dir = 1;

        if (mdn.dn.dn_type == DMU_OT_DSL_DIR) {
                headobj = zfs_to_cpu64(((dsl_dir_phys_t *) DN_BONUS(&mdn.dn))->dd_head_dataset_obj, mdn.endian);

                err = dnode_get(&(data->mos), headobj, DMU_OT_DSL_DATASET, &mdn, data);
                if (err) {
                        printf("zfs failed here 1\n");
                        return;
                }
        }
        make_mdn(&mdn, data);
        err = dnode_get(&mdn, MASTER_NODE_OBJ, DMU_OT_MASTER_NODE,
                                        &dn, data);
        if (err) {
                printf("zfs failed here 2\n");
                return;
        }

        err = zap_lookup(&dn, ZFS_ROOT_OBJ, &objnum, data);
        if (err) {
                printf("zfs failed here 3\n");
                return;
        }

        err = dnode_get(&mdn, objnum, 0, &dn, data);
        if (err) {
                printf("zfs failed here 4\n");
                return;
        }

        info->mtimeset = 1;
        info->mtime = zfs_to_cpu64(((znode_phys_t *) DN_BONUS(&dn.dn))->zp_mtime[0], dn.endian);

        return;
}

static int iterate_zap(const char *name, uint64_t val, struct zfs_data *data)
{
        struct zfs_dirhook_info info;
        dnode_end_t dn;

        memset(&info, 0, sizeof(info));

        dnode_get(&(data->mdn), val, 0, &dn, data);
        info.mtimeset = 1;
        info.mtime = zfs_to_cpu64(((znode_phys_t *) DN_BONUS(&dn.dn))->zp_mtime[0], dn.endian);
        info.dir = (dn.dn.dn_type == DMU_OT_DIRECTORY_CONTENTS);
        debug("zfs type=%d, name=%s\n",
                  (int)dn.dn.dn_type, (char *)name);
        if (!data->userhook)
                return 0;
        return data->userhook(name, &info);
}

static int iterate_zap_fs(const char *name, uint64_t val, struct zfs_data *data)
{
        struct zfs_dirhook_info info;
        dnode_end_t mdn;
        int err;
        err = dnode_get(&(data->mos), val, 0, &mdn, data);
        if (err)
                return 0;
        if (mdn.dn.dn_type != DMU_OT_DSL_DIR)
                return 0;

        fill_fs_info(&info, mdn, data);

        if (!data->userhook)
                return 0;
        return data->userhook(name, &info);
}

static int iterate_zap_snap(const char *name, uint64_t val, struct zfs_data *data)
{
        struct zfs_dirhook_info info;
        char *name2;
        int ret = 0;
        dnode_end_t mdn;
        int err;

        err = dnode_get(&(data->mos), val, 0, &mdn, data);
        if (err)
                return 0;

        if (mdn.dn.dn_type != DMU_OT_DSL_DATASET)
                return 0;

        fill_fs_info(&info, mdn, data);

        name2 = malloc(strlen(name) + 2);
        name2[0] = '@';
        memcpy(name2 + 1, name, strlen(name) + 1);
        if (data->userhook)
                ret = data->userhook(name2, &info);
        free(name2);
        return ret;
}

int
zfs_ls(device_t device, const char *path,
           int (*hook)(const char *, const struct zfs_dirhook_info *))
{
        struct zfs_data *data;
        int err;
        int isfs;

        data = zfs_mount(device);
        if (!data)
                return ZFS_ERR_BAD_FS;

        data->userhook = hook;

        err = dnode_get_fullpath(path, &(data->mdn), 0, &(data->dnode), &isfs, data);
        if (err) {
                zfs_unmount(data);
                return err;
        }
        if (isfs) {
                uint64_t childobj, headobj;
                uint64_t snapobj;
                dnode_end_t dn;
                struct zfs_dirhook_info info;

                fill_fs_info(&info, data->dnode, data);
                hook("@", &info);

                childobj = zfs_to_cpu64(((dsl_dir_phys_t *) DN_BONUS(&data->dnode.dn))->dd_child_dir_zapobj, data->dnode.endian);
                headobj = zfs_to_cpu64(((dsl_dir_phys_t *) DN_BONUS(&data->dnode.dn))->dd_head_dataset_obj, data->dnode.endian);
                err = dnode_get(&(data->mos), childobj,
                                                DMU_OT_DSL_DIR_CHILD_MAP, &dn, data);
                if (err) {
                        zfs_unmount(data);
                        return err;
                }


                zap_iterate(&dn, iterate_zap_fs, data);

                err = dnode_get(&(data->mos), headobj, DMU_OT_DSL_DATASET, &dn, data);
                if (err) {
                        zfs_unmount(data);
                        return err;
                }

                snapobj = zfs_to_cpu64(((dsl_dataset_phys_t *) DN_BONUS(&dn.dn))->ds_snapnames_zapobj, dn.endian);

                err = dnode_get(&(data->mos), snapobj,
                                                DMU_OT_DSL_DS_SNAP_MAP, &dn, data);
                if (err) {
                        zfs_unmount(data);
                        return err;
                }

                zap_iterate(&dn, iterate_zap_snap, data);
        } else {
                if (data->dnode.dn.dn_type != DMU_OT_DIRECTORY_CONTENTS) {
                        zfs_unmount(data);
                        printf("not a directory\n");
                        return ZFS_ERR_BAD_FILE_TYPE;
                }
                zap_iterate(&(data->dnode), iterate_zap, data);
        }
        zfs_unmount(data);
        return ZFS_ERR_NONE;
}