/*
 * Copyright (c) 2007 Doug Rabson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>

/*
 *      Stand-alone file reading package.
 */

#include <stand.h>
#include <sys/disk.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/queue.h>
#include <disk.h>
#include <part.h>
#include <stddef.h>
#include <stdarg.h>
#include <string.h>
#include <bootstrap.h>
#include <inttypes.h>

#include "libzfs.h"

#include "zfsimpl.c"

/* Define the range of indexes to be populated with ZFS Boot Environments */
#define         ZFS_BE_FIRST    4
#define         ZFS_BE_LAST     8

static int      zfs_open(const char *, struct open_file *);
static int      zfs_close(struct open_file *);
static int      zfs_read(struct open_file *, void *, size_t, size_t *);
static off_t    zfs_seek(struct open_file *, off_t, int);
static int      zfs_stat(struct open_file *, struct stat *);
static int      zfs_readdir(struct open_file *, struct dirent *);

struct devsw zfs_dev;

struct fs_ops zfs_fsops = {
        "zfs",
        zfs_open,
        zfs_close,
        zfs_read,
        null_write,
        zfs_seek,
        zfs_stat,
        zfs_readdir
};

/*
 * In-core open file.
 */
struct file {
        off_t           f_seekp;        /* seek pointer */
        dnode_phys_t    f_dnode;
        uint64_t        f_zap_type;     /* zap type for readdir */
        uint64_t        f_num_leafs;    /* number of fzap leaf blocks */
        zap_leaf_phys_t *f_zap_leaf;    /* zap leaf buffer */
};

SLIST_HEAD(zfs_be_list, zfs_be_entry) zfs_be_head =
    SLIST_HEAD_INITIALIZER(zfs_be_head);
struct zfs_be_list *zfs_be_headp;
struct zfs_be_entry {
        const char *name;
        SLIST_ENTRY(zfs_be_entry) entries;
} *zfs_be, *zfs_be_tmp;

/*
 * Open a file.
 */
static int
zfs_open(const char *upath, struct open_file *f)
{
        struct zfsmount *mount = (struct zfsmount *)f->f_devdata;
        struct file *fp;
        int rc;

        if (f->f_dev != &zfs_dev)
                return (EINVAL);

        /* allocate file system specific data structure */
        fp = calloc(1, sizeof (struct file));
        if (fp == NULL)
                return (ENOMEM);
        f->f_fsdata = fp;

        rc = zfs_lookup(mount, upath, &fp->f_dnode);
        fp->f_seekp = 0;
        if (rc) {
                f->f_fsdata = NULL;
                free(fp);
        }
        return (rc);
}

static int
zfs_close(struct open_file *f)
{
        struct file *fp = (struct file *)f->f_fsdata;

        dnode_cache_obj = NULL;
        f->f_fsdata = NULL;

        free(fp);
        return (0);
}

/*
 * Copy a portion of a file into kernel memory.
 * Cross block boundaries when necessary.
 */
static int
zfs_read(struct open_file *f, void *start, size_t size, size_t *resid)
{
        const spa_t *spa = ((struct zfsmount *)f->f_devdata)->spa;
        struct file *fp = (struct file *)f->f_fsdata;
        struct stat sb;
        size_t n;
        int rc;

        rc = zfs_stat(f, &sb);
        if (rc)
                return (rc);
        n = size;
        if (fp->f_seekp + n > sb.st_size)
                n = sb.st_size - fp->f_seekp;

        rc = dnode_read(spa, &fp->f_dnode, fp->f_seekp, start, n);
        if (rc)
                return (rc);

        fp->f_seekp += n;
        if (resid)
                *resid = size - n;

        return (0);
}

static off_t
zfs_seek(struct open_file *f, off_t offset, int where)
{
        struct file *fp = (struct file *)f->f_fsdata;
        struct stat sb;
        int error;

        switch (where) {
        case SEEK_SET:
                fp->f_seekp = offset;
                break;
        case SEEK_CUR:
                fp->f_seekp += offset;
                break;
        case SEEK_END:
                error = zfs_stat(f, &sb);
                if (error != 0) {
                        errno = error;
                        return (-1);
                }
                fp->f_seekp = sb.st_size - offset;
                break;
        default:
                errno = EINVAL;
                return (-1);
        }
        return (fp->f_seekp);
}

static int
zfs_stat(struct open_file *f, struct stat *sb)
{
        const spa_t *spa = ((struct zfsmount *)f->f_devdata)->spa;
        struct file *fp = (struct file *)f->f_fsdata;

        return (zfs_dnode_stat(spa, &fp->f_dnode, sb));
}

static int
zfs_readdir(struct open_file *f, struct dirent *d)
{
        const spa_t *spa = ((struct zfsmount *)f->f_devdata)->spa;
        struct file *fp = (struct file *)f->f_fsdata;
        mzap_ent_phys_t mze;
        struct stat sb;
        size_t bsize = fp->f_dnode.dn_datablkszsec << SPA_MINBLOCKSHIFT;
        int rc;

        rc = zfs_stat(f, &sb);
        if (rc)
                return (rc);
        if (!S_ISDIR(sb.st_mode))
                return (ENOTDIR);

        /*
         * If this is the first read, get the zap type.
         */
        if (fp->f_seekp == 0) {
                rc = dnode_read(spa, &fp->f_dnode, 0, &fp->f_zap_type,
                    sizeof (fp->f_zap_type));
                if (rc)
                        return (rc);

                if (fp->f_zap_type == ZBT_MICRO) {
                        fp->f_seekp = offsetof(mzap_phys_t, mz_chunk);
                } else {
                        rc = dnode_read(spa, &fp->f_dnode,
                            offsetof(zap_phys_t, zap_num_leafs),
                            &fp->f_num_leafs, sizeof (fp->f_num_leafs));
                        if (rc)
                                return (rc);

                        fp->f_seekp = bsize;
                        fp->f_zap_leaf = malloc(bsize);
                        if (fp->f_zap_leaf == NULL)
                                return (ENOMEM);
                        rc = dnode_read(spa, &fp->f_dnode, fp->f_seekp,
                            fp->f_zap_leaf, bsize);
                        if (rc)
                                return (rc);
                }
        }

        if (fp->f_zap_type == ZBT_MICRO) {
        mzap_next:
                if (fp->f_seekp >= bsize)
                        return (ENOENT);

                rc = dnode_read(spa, &fp->f_dnode, fp->f_seekp, &mze,
                    sizeof (mze));
                if (rc)
                        return (rc);
                fp->f_seekp += sizeof (mze);

                if (!mze.mze_name[0])
                        goto mzap_next;

                d->d_fileno = ZFS_DIRENT_OBJ(mze.mze_value);
                d->d_type = ZFS_DIRENT_TYPE(mze.mze_value);
                strcpy(d->d_name, mze.mze_name);
                d->d_namlen = strlen(d->d_name);
                return (0);
        } else {
                zap_leaf_t zl;
                zap_leaf_chunk_t *zc, *nc;
                int chunk;
                size_t namelen;
                char *p;
                uint64_t value;

                /*
                 * Initialise this so we can use the ZAP size
                 * calculating macros.
                 */
                zl.l_bs = ilog2(bsize);
                zl.l_phys = fp->f_zap_leaf;

                /*
                 * Figure out which chunk we are currently looking at
                 * and consider seeking to the next leaf. We use the
                 * low bits of f_seekp as a simple chunk index.
                 */
        fzap_next:
                chunk = fp->f_seekp & (bsize - 1);
                if (chunk == ZAP_LEAF_NUMCHUNKS(&zl)) {
                        fp->f_seekp = (fp->f_seekp & ~(bsize - 1)) + bsize;
                        chunk = 0;

                        /*
                         * Check for EOF and read the new leaf.
                         */
                        if (fp->f_seekp >= bsize * fp->f_num_leafs)
                                return (ENOENT);

                        rc = dnode_read(spa, &fp->f_dnode, fp->f_seekp,
                            fp->f_zap_leaf, bsize);
                        if (rc)
                                return (rc);
                }

                zc = &ZAP_LEAF_CHUNK(&zl, chunk);
                fp->f_seekp++;
                if (zc->l_entry.le_type != ZAP_CHUNK_ENTRY)
                        goto fzap_next;

                namelen = zc->l_entry.le_name_numints;
                if (namelen > sizeof (d->d_name))
                        namelen = sizeof (d->d_name);

                /*
                 * Paste the name back together.
                 */
                nc = &ZAP_LEAF_CHUNK(&zl, zc->l_entry.le_name_chunk);
                p = d->d_name;
                while (namelen > 0) {
                        int len;
                        len = namelen;
                        if (len > ZAP_LEAF_ARRAY_BYTES)
                                len = ZAP_LEAF_ARRAY_BYTES;
                        memcpy(p, nc->l_array.la_array, len);
                        p += len;
                        namelen -= len;
                        nc = &ZAP_LEAF_CHUNK(&zl, nc->l_array.la_next);
                }
                d->d_name[sizeof (d->d_name) - 1] = 0;

                /*
                 * Assume the first eight bytes of the value are
                 * a uint64_t.
                 */
                value = fzap_leaf_value(&zl, zc);

                d->d_fileno = ZFS_DIRENT_OBJ(value);
                d->d_type = ZFS_DIRENT_TYPE(value);
                d->d_namlen = strlen(d->d_name);

                return (0);
        }
}

static int
vdev_read(vdev_t *vdev __unused, void *priv, off_t offset, void *buf,
    size_t bytes)
{
        int fd, ret;
        size_t res, head, tail, total_size, full_sec_size;
        unsigned secsz, do_tail_read;
        off_t start_sec;
        char *outbuf, *bouncebuf;

        fd = (uintptr_t)priv;
        outbuf = (char *)buf;
        bouncebuf = NULL;

        ret = ioctl(fd, DIOCGSECTORSIZE, &secsz);
        if (ret != 0)
                return (ret);

        /* BEGIN CSTYLED */
        /*
         * Handling reads of arbitrary offset and size - multi-sector case
         * and single-sector case.
         *
         *                        Multi-sector Case
         *                (do_tail_read = true if tail > 0)
         *
         *   |<----------------------total_size--------------------->|
         *   |                                                       |
         *   |<--head-->|<--------------bytes------------>|<--tail-->|
         *   |          |                                 |          |
         *   |          |       |<~full_sec_size~>|       |          |
         *   +------------------+                 +------------------+
         *   |          |0101010|     .  .  .     |0101011|          |
         *   +------------------+                 +------------------+
         *         start_sec                         start_sec + n
         *
         *
         *                      Single-sector Case
         *                    (do_tail_read = false)
         *
         *              |<------total_size = secsz----->|
         *              |                               |
         *              |<-head->|<---bytes--->|<-tail->|
         *              +-------------------------------+
         *              |        |0101010101010|        |
         *              +-------------------------------+
         *                          start_sec
         */
        /* END CSTYLED */
        start_sec = offset / secsz;
        head = offset % secsz;
        total_size = roundup2(head + bytes, secsz);
        tail = total_size - (head + bytes);
        do_tail_read = ((tail > 0) && (head + bytes > secsz));
        full_sec_size = total_size;
        if (head > 0)
                full_sec_size -= secsz;
        if (do_tail_read)
                full_sec_size -= secsz;

        /* Return of partial sector data requires a bounce buffer. */
        if ((head > 0) || do_tail_read || bytes < secsz) {
                bouncebuf = malloc(secsz);
                if (bouncebuf == NULL) {
                        printf("vdev_read: out of memory\n");
                        return (ENOMEM);
                }
        }

        if (lseek(fd, start_sec * secsz, SEEK_SET) == -1) {
                ret = errno;
                goto error;
        }

        /* Partial data return from first sector */
        if (head > 0) {
                res = read(fd, bouncebuf, secsz);
                if (res != secsz) {
                        ret = EIO;
                        goto error;
                }
                memcpy(outbuf, bouncebuf + head, min(secsz - head, bytes));
                outbuf += min(secsz - head, bytes);
        }

        /* Full data return from read sectors */
        if (full_sec_size > 0) {
                if (bytes < full_sec_size) {
                        res = read(fd, bouncebuf, secsz);
                        if (res != secsz) {
                                ret = EIO;
                                goto error;
                        }
                        memcpy(outbuf, bouncebuf, bytes);
                } else {
                        res = read(fd, outbuf, full_sec_size);
                        if (res != full_sec_size) {
                                ret = EIO;
                                goto error;
                        }
                        outbuf += full_sec_size;
                }
        }

        /* Partial data return from last sector */
        if (do_tail_read) {
                res = read(fd, bouncebuf, secsz);
                if (res != secsz) {
                        ret = EIO;
                        goto error;
                }
                memcpy(outbuf, bouncebuf, secsz - tail);
        }

        ret = 0;
error:
        free(bouncebuf);
        return (ret);
}

static int
vdev_write(vdev_t *vdev, off_t offset, void *buf, size_t bytes)
{
        int fd, ret;
        size_t head, tail, total_size, full_sec_size;
        unsigned secsz, do_tail_write;
        off_t start_sec;
        ssize_t res;
        char *outbuf, *bouncebuf;

        fd = (uintptr_t)vdev->v_priv;
        outbuf = (char *)buf;
        bouncebuf = NULL;

        ret = ioctl(fd, DIOCGSECTORSIZE, &secsz);
        if (ret != 0)
                return (ret);

        start_sec = offset / secsz;
        head = offset % secsz;
        total_size = roundup2(head + bytes, secsz);
        tail = total_size - (head + bytes);
        do_tail_write = ((tail > 0) && (head + bytes > secsz));
        full_sec_size = total_size;
        if (head > 0)
                full_sec_size -= secsz;
        if (do_tail_write)
                full_sec_size -= secsz;

        /* Partial sector write requires a bounce buffer. */
        if ((head > 0) || do_tail_write || bytes < secsz) {
                bouncebuf = malloc(secsz);
                if (bouncebuf == NULL) {
                        printf("vdev_write: out of memory\n");
                        return (ENOMEM);
                }
        }

        if (lseek(fd, start_sec * secsz, SEEK_SET) == -1) {
                ret = errno;
                goto error;
        }

        /* Partial data for first sector */
        if (head > 0) {
                res = read(fd, bouncebuf, secsz);
                if ((unsigned)res != secsz) {
                        ret = EIO;
                        goto error;
                }
                memcpy(bouncebuf + head, outbuf, min(secsz - head, bytes));
                (void) lseek(fd, -secsz, SEEK_CUR);
                res = write(fd, bouncebuf, secsz);
                if ((unsigned)res != secsz) {
                        ret = EIO;
                        goto error;
                }
                outbuf += min(secsz - head, bytes);
        }

        /*
         * Full data write to sectors.
         * Note, there is still corner case where we write
         * to sector boundary, but less than sector size, e.g. write 512B
         * to 4k sector.
         */
        if (full_sec_size > 0) {
                if (bytes < full_sec_size) {
                        res = read(fd, bouncebuf, secsz);
                        if ((unsigned)res != secsz) {
                                ret = EIO;
                                goto error;
                        }
                        memcpy(bouncebuf, outbuf, bytes);
                        (void) lseek(fd, -secsz, SEEK_CUR);
                        res = write(fd, bouncebuf, secsz);
                        if ((unsigned)res != secsz) {
                                ret = EIO;
                                goto error;
                        }
                } else {
                        res = write(fd, outbuf, full_sec_size);
                        if ((unsigned)res != full_sec_size) {
                                ret = EIO;
                                goto error;
                        }
                        outbuf += full_sec_size;
                }
        }

        /* Partial data write to last sector */
        if (do_tail_write) {
                res = read(fd, bouncebuf, secsz);
                if ((unsigned)res != secsz) {
                        ret = EIO;
                        goto error;
                }
                memcpy(bouncebuf, outbuf, secsz - tail);
                (void) lseek(fd, -secsz, SEEK_CUR);
                res = write(fd, bouncebuf, secsz);
                if ((unsigned)res != secsz) {
                        ret = EIO;
                        goto error;
                }
        }

        ret = 0;
error:
        free(bouncebuf);
        return (ret);
}

static int
zfs_dev_init(void)
{
        spa_t *spa;
        spa_t *next;
        spa_t *prev;

        zfs_init();
        if (archsw.arch_zfs_probe == NULL)
                return (ENXIO);
        archsw.arch_zfs_probe();

        prev = NULL;
        spa = STAILQ_FIRST(&zfs_pools);
        while (spa != NULL) {
                next = STAILQ_NEXT(spa, spa_link);
                if (zfs_spa_init(spa)) {
                        if (prev == NULL)
                                STAILQ_REMOVE_HEAD(&zfs_pools, spa_link);
                        else
                                STAILQ_REMOVE_AFTER(&zfs_pools, prev, spa_link);
                } else
                        prev = spa;
                spa = next;
        }
        return (0);
}

struct zfs_probe_args {
        int             fd;
        const char      *devname;
        uint64_t        *pool_guid;
        unsigned        secsz;
};

static int
zfs_diskread(void *arg, void *buf, size_t blocks, uint64_t offset)
{
        struct zfs_probe_args *ppa;

        ppa = (struct zfs_probe_args *)arg;
        return (vdev_read(NULL, (void *)(uintptr_t)ppa->fd,
            offset * ppa->secsz, buf, blocks * ppa->secsz));
}

static int
zfs_probe(int fd, uint64_t *pool_guid)
{
        spa_t *spa;
        int ret;

        spa = NULL;
        ret = vdev_probe(vdev_read, vdev_write, (void *)(uintptr_t)fd, &spa);
        if (ret == 0 && pool_guid != NULL)
                *pool_guid = spa->spa_guid;
        return (ret);
}

static int
zfs_probe_partition(void *arg, const char *partname,
    const struct ptable_entry *part)
{
        struct zfs_probe_args *ppa, pa;
        struct ptable *table;
        char devname[32];
        int ret = 0;

        /* filter out partitions *not* used by zfs */
        switch (part->type) {
        case PART_EFI:          /* efi system partition */
        case PART_RESERVED:     /* efi reserverd */
        case PART_VTOC_BOOT:    /* vtoc boot area */
        case PART_VTOC_SWAP:
                return (ret);
        default:
                break;
        }
        ppa = (struct zfs_probe_args *)arg;
        strncpy(devname, ppa->devname, strlen(ppa->devname) - 1);
        devname[strlen(ppa->devname) - 1] = '\0';
        snprintf(devname, sizeof (devname), "%s%s:", devname, partname);
        pa.fd = open(devname, O_RDWR);
        if (pa.fd == -1)
                return (ret);
        ret = zfs_probe(pa.fd, ppa->pool_guid);
        if (ret == 0)
                return (ret);
        if (part->type == PART_SOLARIS2) {
                pa.devname = devname;
                pa.pool_guid = ppa->pool_guid;
                pa.secsz = ppa->secsz;
                table = ptable_open(&pa, part->end - part->start + 1,
                    ppa->secsz, zfs_diskread);
                if (table != NULL) {
                        enum ptable_type pt = ptable_gettype(table);

                        if (pt == PTABLE_VTOC8 || pt == PTABLE_VTOC)
                                ptable_iterate(table, &pa, zfs_probe_partition);
                        ptable_close(table);
                }
        }
        close(pa.fd);
        return (0);
}

/*
 * Return bootenv nvlist from pool label.
 */
int
zfs_get_bootenv(void *vdev, nvlist_t **benvp)
{
        struct zfs_devdesc *dev = (struct zfs_devdesc *)vdev;
        nvlist_t *benv = NULL;
        vdev_t *vd;
        spa_t *spa;

        if (dev->dd.d_dev->dv_type != DEVT_ZFS)
                return (ENOTSUP);

        if ((spa = spa_find_by_dev(dev)) == NULL)
                return (ENXIO);

        if (spa->spa_bootenv == NULL) {
                STAILQ_FOREACH(vd, &spa->spa_root_vdev->v_children,
                    v_childlink) {
                        benv = vdev_read_bootenv(vd);

                        if (benv != NULL)
                                break;
                }
                spa->spa_bootenv = benv;
        } else {
                benv = spa->spa_bootenv;
        }

        if (benv == NULL)
                return (ENOENT);

        *benvp = benv;
        return (0);
}

/*
 * Store nvlist to pool label bootenv area. Also updates cached pointer in spa.
 */
int
zfs_set_bootenv(void *vdev, nvlist_t *benv)
{
        struct zfs_devdesc *dev = (struct zfs_devdesc *)vdev;
        spa_t *spa;
        vdev_t *vd;

        if (dev->dd.d_dev->dv_type != DEVT_ZFS)
                return (ENOTSUP);

        if ((spa = spa_find_by_dev(dev)) == NULL)
                return (ENXIO);

        STAILQ_FOREACH(vd, &spa->spa_root_vdev->v_children, v_childlink) {
                vdev_write_bootenv(vd, benv);
        }

        spa->spa_bootenv = benv;
        return (0);
}

/*
 * Get bootonce value by key. The bootonce <key, value> pair is removed
 * from the bootenv nvlist and the remaining nvlist is committed back to disk.
 */
int
zfs_get_bootonce(void *vdev, const char *key, char *buf, size_t size)
{
        nvlist_t *benv;
        char *result = NULL;
        int result_size, rv;

        if ((rv = zfs_get_bootenv(vdev, &benv)) != 0)
                return (rv);

        if ((rv = nvlist_find(benv, key, DATA_TYPE_STRING, NULL,
            &result, &result_size)) == 0) {
                if (result_size == 0) {
                        /* ignore empty string */
                        rv = ENOENT;
                } else {
                        size = MIN((size_t)result_size + 1, size);
                        strlcpy(buf, result, size);
                }
                (void) nvlist_remove(benv, key, DATA_TYPE_STRING);
                (void) zfs_set_bootenv(vdev, benv);
        }

        return (rv);
}

/*
 * nvstore backend.
 */

static int zfs_nvstore_setter(void *, int, const char *,
    const void *, size_t);
static int zfs_nvstore_setter_str(void *, const char *, const char *,
    const char *);
static int zfs_nvstore_unset_impl(void *, const char *, bool);
static int zfs_nvstore_setenv(void *, void *);

/*
 * nvstore is only present for current rootfs pool.
 */
static int
zfs_nvstore_sethook(struct env_var *ev, int flags __unused, const void *value)
{
        struct zfs_devdesc *dev;
        int rv;

        archsw.arch_getdev((void **)&dev, NULL, NULL);
        if (dev == NULL)
                return (ENXIO);

        rv = zfs_nvstore_setter_str(dev, NULL, ev->ev_name, value);

        free(dev);
        return (rv);
}

/*
 * nvstore is only present for current rootfs pool.
 */
static int
zfs_nvstore_unsethook(struct env_var *ev)
{
        struct zfs_devdesc *dev;
        int rv;

        archsw.arch_getdev((void **)&dev, NULL, NULL);
        if (dev == NULL)
                return (ENXIO);

        rv = zfs_nvstore_unset_impl(dev, ev->ev_name, false);

        free(dev);
        return (rv);
}

static int
zfs_nvstore_getter(void *vdev, const char *name, void **data)
{
        struct zfs_devdesc *dev = (struct zfs_devdesc *)vdev;
        spa_t *spa;
        nvlist_t *nv;
        char *str, **ptr;
        int size;
        int rv;

        if (dev->dd.d_dev->dv_type != DEVT_ZFS)
                return (ENOTSUP);

        if ((spa = spa_find_by_dev(dev)) == NULL)
                return (ENXIO);

        if (spa->spa_bootenv == NULL)
                return (ENXIO);

        if (nvlist_find(spa->spa_bootenv, OS_NVSTORE, DATA_TYPE_NVLIST,
            NULL, &nv, NULL) != 0)
                return (ENOENT);

        rv = nvlist_find(nv, name, DATA_TYPE_STRING, NULL, &str, &size);
        if (rv == 0) {
                ptr = (char **)data;
                asprintf(ptr, "%.*s", size, str);
                if (*data == NULL)
                        rv = ENOMEM;
        }
        nvlist_destroy(nv);
        return (rv);
}

static int
zfs_nvstore_setter(void *vdev, int type, const char *name,
    const void *data, size_t size)
{
        struct zfs_devdesc *dev = (struct zfs_devdesc *)vdev;
        spa_t *spa;
        nvlist_t *nv;
        int rv;
        bool env_set = true;

        if (dev->dd.d_dev->dv_type != DEVT_ZFS)
                return (ENOTSUP);

        if ((spa = spa_find_by_dev(dev)) == NULL)
                return (ENXIO);

        if (spa->spa_bootenv == NULL)
                return (ENXIO);

        if (nvlist_find(spa->spa_bootenv, OS_NVSTORE, DATA_TYPE_NVLIST,
            NULL, &nv, NULL) != 0) {
                nv = nvlist_create(NV_UNIQUE_NAME);
                if (nv == NULL)
                        return (ENOMEM);
        }

        rv = 0;
        switch (type) {
        case DATA_TYPE_INT8:
                if (size != sizeof (int8_t)) {
                        rv = EINVAL;
                        break;
                }
                rv = nvlist_add_int8(nv, name, *(int8_t *)data);
                break;

        case DATA_TYPE_INT16:
                if (size != sizeof (int16_t)) {
                        rv = EINVAL;
                        break;
                }
                rv = nvlist_add_int16(nv, name, *(int16_t *)data);
                break;

        case DATA_TYPE_INT32:
                if (size != sizeof (int32_t)) {
                        rv = EINVAL;
                        break;
                }
                rv = nvlist_add_int32(nv, name, *(int32_t *)data);
                break;

        case DATA_TYPE_INT64:
                if (size != sizeof (int64_t)) {
                        rv = EINVAL;
                        break;
                }
                rv = nvlist_add_int64(nv, name, *(int64_t *)data);
                break;

        case DATA_TYPE_BYTE:
                if (size != sizeof (uint8_t)) {
                        rv = EINVAL;
                        break;
                }
                rv = nvlist_add_byte(nv, name, *(int8_t *)data);
                break;

        case DATA_TYPE_UINT8:
                if (size != sizeof (uint8_t)) {
                        rv = EINVAL;
                        break;
                }
                rv = nvlist_add_uint8(nv, name, *(int8_t *)data);
                break;
        case DATA_TYPE_UINT16:
                if (size != sizeof (uint16_t)) {
                        rv = EINVAL;
                        break;
                }
                rv = nvlist_add_uint16(nv, name, *(uint16_t *)data);
                break;

        case DATA_TYPE_UINT32:
                if (size != sizeof (uint32_t)) {
                        rv = EINVAL;
                        break;
                }
                rv = nvlist_add_uint32(nv, name, *(uint32_t *)data);
                break;

        case DATA_TYPE_UINT64:
                if (size != sizeof (uint64_t)) {
                        rv = EINVAL;
                        break;
                }
                rv = nvlist_add_uint64(nv, name, *(uint64_t *)data);
                break;

        case DATA_TYPE_STRING:
                rv = nvlist_add_string(nv, name, data);
                break;

        case DATA_TYPE_BOOLEAN_VALUE:
                if (size != sizeof (boolean_t)) {
                        rv = EINVAL;
                        break;
                }
                rv = nvlist_add_boolean_value(nv, name, *(boolean_t *)data);
                break;

        default:
                rv = EINVAL;
                break;
        }

        if (rv == 0) {
                rv = nvlist_add_nvlist(spa->spa_bootenv, OS_NVSTORE, nv);
                if (rv == 0) {
                        rv = zfs_set_bootenv(vdev, spa->spa_bootenv);
                }
                if (rv == 0) {
                        if (env_set) {
                                rv = zfs_nvstore_setenv(vdev,
                                    nvpair_find(nv, name));
                        } else {
                                env_discard(env_getenv(name));
                                rv = 0;
                        }
                }
        }

        nvlist_destroy(nv);
        return (rv);
}

static int
get_int64(const char *data, int64_t *ip)
{
        char *end;
        int64_t val;

        errno = 0;
        val = strtoll(data, &end, 0);
        if (errno != 0 || *data == '\0' || *end != '\0')
                return (EINVAL);

        *ip = val;
        return (0);
}

static int
get_uint64(const char *data, uint64_t *ip)
{
        char *end;
        uint64_t val;

        errno = 0;
        val = strtoull(data, &end, 0);
        if (errno != 0 || *data == '\0' || *end != '\0')
                return (EINVAL);

        *ip = val;
        return (0);
}

/*
 * Translate textual data to data type. If type is not set, and we are
 * creating new pair, use DATA_TYPE_STRING.
 */
static int
zfs_nvstore_setter_str(void *vdev, const char *type, const char *name,
    const char *data)
{
        struct zfs_devdesc *dev = (struct zfs_devdesc *)vdev;
        spa_t *spa;
        nvlist_t *nv;
        int rv;
        data_type_t dt;
        int64_t val;
        uint64_t uval;

        if (dev->dd.d_dev->dv_type != DEVT_ZFS)
                return (ENOTSUP);

        if ((spa = spa_find_by_dev(dev)) == NULL)
                return (ENXIO);

        if (spa->spa_bootenv == NULL)
                return (ENXIO);

        if (nvlist_find(spa->spa_bootenv, OS_NVSTORE, DATA_TYPE_NVLIST,
            NULL, &nv, NULL) != 0) {
                nv = NULL;
        }

        if (type == NULL) {
                nvp_header_t *nvh;

                /*
                 * if there is no existing pair, default to string.
                 * Otherwise, use type from existing pair.
                 */
                nvh = nvpair_find(nv, name);
                if (nvh == NULL) {
                        dt = DATA_TYPE_STRING;
                } else {
                        nv_string_t *nvp_name;
                        nv_pair_data_t *nvp_data;

                        nvp_name = (nv_string_t *)(nvh + 1);
                        nvp_data = (nv_pair_data_t *)(&nvp_name->nv_data[0] +
                            NV_ALIGN4(nvp_name->nv_size));
                        dt = nvp_data->nv_type;
                }
        } else {
                dt = nvpair_type_from_name(type);
        }
        nvlist_destroy(nv);

        rv = 0;
        switch (dt) {
        case DATA_TYPE_INT8:
                rv = get_int64(data, &val);
                if (rv == 0) {
                        int8_t v = val;

                        rv = zfs_nvstore_setter(vdev, dt, name, &v, sizeof (v));
                }
                break;
        case DATA_TYPE_INT16:
                rv = get_int64(data, &val);
                if (rv == 0) {
                        int16_t v = val;

                        rv = zfs_nvstore_setter(vdev, dt, name, &v, sizeof (v));
                }
                break;
        case DATA_TYPE_INT32:
                rv = get_int64(data, &val);
                if (rv == 0) {
                        int32_t v = val;

                        rv = zfs_nvstore_setter(vdev, dt, name, &v, sizeof (v));
                }
                break;
        case DATA_TYPE_INT64:
                rv = get_int64(data, &val);
                if (rv == 0) {
                        rv = zfs_nvstore_setter(vdev, dt, name, &val,
                            sizeof (val));
                }
                break;

        case DATA_TYPE_BYTE:
                rv = get_uint64(data, &uval);
                if (rv == 0) {
                        uint8_t v = uval;

                        rv = zfs_nvstore_setter(vdev, dt, name, &v, sizeof (v));
                }
                break;

        case DATA_TYPE_UINT8:
                rv = get_uint64(data, &uval);
                if (rv == 0) {
                        uint8_t v = uval;

                        rv = zfs_nvstore_setter(vdev, dt, name, &v, sizeof (v));
                }
                break;

        case DATA_TYPE_UINT16:
                rv = get_uint64(data, &uval);
                if (rv == 0) {
                        uint16_t v = uval;

                        rv = zfs_nvstore_setter(vdev, dt, name, &v, sizeof (v));
                }
                break;

        case DATA_TYPE_UINT32:
                rv = get_uint64(data, &uval);
                if (rv == 0) {
                        uint32_t v = uval;

                        rv = zfs_nvstore_setter(vdev, dt, name, &v, sizeof (v));
                }
                break;

        case DATA_TYPE_UINT64:
                rv = get_uint64(data, &uval);
                if (rv == 0) {
                        rv = zfs_nvstore_setter(vdev, dt, name, &uval,
                            sizeof (uval));
                }
                break;

        case DATA_TYPE_STRING:
                rv = zfs_nvstore_setter(vdev, dt, name, data, strlen(data) + 1);
                break;

        case DATA_TYPE_BOOLEAN_VALUE:
                rv = get_int64(data, &val);
                if (rv == 0) {
                        boolean_t v = val;

                        rv = zfs_nvstore_setter(vdev, dt, name, &v, sizeof (v));
                }
                break;

        default:
                rv = EINVAL;
        }
        return (rv);
}

static int
zfs_nvstore_unset_impl(void *vdev, const char *name, bool unset_env)
{
        struct zfs_devdesc *dev = (struct zfs_devdesc *)vdev;
        spa_t *spa;
        nvlist_t *nv;
        int rv;

        if (dev->dd.d_dev->dv_type != DEVT_ZFS)
                return (ENOTSUP);

        if ((spa = spa_find_by_dev(dev)) == NULL)
                return (ENXIO);

        if (spa->spa_bootenv == NULL)
                return (ENXIO);

        if (nvlist_find(spa->spa_bootenv, OS_NVSTORE, DATA_TYPE_NVLIST,
            NULL, &nv, NULL) != 0)
                return (ENOENT);

        rv = nvlist_remove(nv, name, DATA_TYPE_UNKNOWN);
        if (rv == 0) {
                if (nvlist_next_nvpair(nv, NULL) == NULL) {
                        rv = nvlist_remove(spa->spa_bootenv, OS_NVSTORE,
                            DATA_TYPE_NVLIST);
                } else {
                        rv = nvlist_add_nvlist(spa->spa_bootenv,
                            OS_NVSTORE, nv);
                }
                if (rv == 0)
                        rv = zfs_set_bootenv(vdev, spa->spa_bootenv);
        }

        if (unset_env) {
                struct env_var *ev = env_getenv(name);

                if (ev != NULL)
                        env_discard(ev);
        }
        return (rv);
}

static int
zfs_nvstore_unset(void *vdev, const char *name)
{
        return (zfs_nvstore_unset_impl(vdev, name, true));
}

static int
zfs_nvstore_print(void *vdev __unused, void *ptr)
{

        nvpair_print(ptr, 0);
        return (0);
}

/*
 * Create environment variable from nvpair.
 * set hook will update nvstore with new value, unset hook will remove
 * variable from nvstore.
 */
static int
zfs_nvstore_setenv(void *vdev __unused, void *ptr)
{
        nvp_header_t *nvh = ptr;
        nv_string_t *nvp_name, *nvp_value;
        nv_pair_data_t *nvp_data;
        char *name, *value;
        int rv = 0;

        if (nvh == NULL)
                return (ENOENT);

        nvp_name = (nv_string_t *)(nvh + 1);
        nvp_data = (nv_pair_data_t *)(&nvp_name->nv_data[0] +
            NV_ALIGN4(nvp_name->nv_size));

        if ((name = nvstring_get(nvp_name)) == NULL)
                return (ENOMEM);

        value = NULL;
        switch (nvp_data->nv_type) {
        case DATA_TYPE_BYTE:
        case DATA_TYPE_UINT8:
                (void) asprintf(&value, "%uc",
                    *(unsigned *)&nvp_data->nv_data[0]);
                if (value == NULL)
                        rv = ENOMEM;
                break;

        case DATA_TYPE_INT8:
                (void) asprintf(&value, "%c", *(int *)&nvp_data->nv_data[0]);
                if (value == NULL)
                        rv = ENOMEM;
                break;

        case DATA_TYPE_INT16:
                (void) asprintf(&value, "%hd", *(short *)&nvp_data->nv_data[0]);
                if (value == NULL)
                        rv = ENOMEM;
                break;

        case DATA_TYPE_UINT16:
                (void) asprintf(&value, "%hu",
                    *(unsigned short *)&nvp_data->nv_data[0]);
                if (value == NULL)
                        rv = ENOMEM;
                break;

        case DATA_TYPE_BOOLEAN_VALUE:
        case DATA_TYPE_INT32:
                (void) asprintf(&value, "%d", *(int *)&nvp_data->nv_data[0]);
                if (value == NULL)
                        rv = ENOMEM;
                break;

        case DATA_TYPE_UINT32:
                (void) asprintf(&value, "%u",
                    *(unsigned *)&nvp_data->nv_data[0]);
                if (value == NULL)
                        rv = ENOMEM;
                break;

        case DATA_TYPE_INT64:
                (void) asprintf(&value, "%jd",
                    (intmax_t)*(int64_t *)&nvp_data->nv_data[0]);
                if (value == NULL)
                        rv = ENOMEM;
                break;

        case DATA_TYPE_UINT64:
                (void) asprintf(&value, "%ju",
                    (uintmax_t)*(uint64_t *)&nvp_data->nv_data[0]);
                if (value == NULL)
                        rv = ENOMEM;
                break;

        case DATA_TYPE_STRING:
                nvp_value = (nv_string_t *)&nvp_data->nv_data[0];
                if ((value = nvstring_get(nvp_value)) == NULL) {
                        rv = ENOMEM;
                        break;
                }
                break;

        default:
                rv = EINVAL;
                break;
        }

        if (value != NULL) {
                rv = env_setenv(name, EV_VOLATILE | EV_NOHOOK, value,
                    zfs_nvstore_sethook, zfs_nvstore_unsethook);
                free(value);
        }
        free(name);
        return (rv);
}

static int
zfs_nvstore_iterate(void *vdev, int (*cb)(void *, void *))
{
        struct zfs_devdesc *dev = (struct zfs_devdesc *)vdev;
        spa_t *spa;
        nvlist_t *nv;
        nvp_header_t *nvh;
        int rv;

        if (dev->dd.d_dev->dv_type != DEVT_ZFS)
                return (ENOTSUP);

        if ((spa = spa_find_by_dev(dev)) == NULL)
                return (ENXIO);

        if (spa->spa_bootenv == NULL)
                return (ENXIO);

        if (nvlist_find(spa->spa_bootenv, OS_NVSTORE, DATA_TYPE_NVLIST,
            NULL, &nv, NULL) != 0)
                return (ENOENT);

        rv = 0;
        nvh = NULL;
        while ((nvh = nvlist_next_nvpair(nv, nvh)) != NULL) {
                rv = cb(vdev, nvh);
                if (rv != 0)
                        break;
        }
        return (rv);
}

nvs_callbacks_t nvstore_zfs_cb = {
        .nvs_getter = zfs_nvstore_getter,
        .nvs_setter = zfs_nvstore_setter,
        .nvs_setter_str = zfs_nvstore_setter_str,
        .nvs_unset = zfs_nvstore_unset,
        .nvs_print = zfs_nvstore_print,
        .nvs_iterate = zfs_nvstore_iterate
};

int
zfs_attach_nvstore(void *vdev)
{
        struct zfs_devdesc *dev = vdev;
        spa_t *spa;
        uint64_t version;
        int rv;

        if (dev->dd.d_dev->dv_type != DEVT_ZFS)
                return (ENOTSUP);

        if ((spa = spa_find_by_dev(dev)) == NULL)
                return (ENXIO);

        rv = nvlist_find(spa->spa_bootenv, BOOTENV_VERSION, DATA_TYPE_UINT64,
            NULL, &version, NULL);

        if (rv != 0 || version != VB_NVLIST) {
                return (ENXIO);
        }

        dev = malloc(sizeof (*dev));
        if (dev == NULL)
                return (ENOMEM);
        memcpy(dev, vdev, sizeof (*dev));

        rv = nvstore_init(spa->spa_name, &nvstore_zfs_cb, dev);
        if (rv != 0)
                free(dev);
        else
                rv = zfs_nvstore_iterate(dev, zfs_nvstore_setenv);
        return (rv);
}

int
zfs_probe_dev(const char *devname, uint64_t *pool_guid)
{
        struct disk_devdesc *dev;
        struct ptable *table;
        struct zfs_probe_args pa;
        uint64_t mediasz;
        int ret;

        if (pool_guid)
                *pool_guid = 0;
        pa.fd = open(devname, O_RDWR);
        if (pa.fd == -1)
                return (ENXIO);
        /*
         * We will not probe the whole disk, we can not boot from such
         * disks and some systems will misreport the disk sizes and will
         * hang while accessing the disk.
         */
        if (archsw.arch_getdev((void **)&dev, devname, NULL) == 0) {
                int partition = dev->d_partition;
                int slice = dev->d_slice;

                free(dev);
                if (partition != D_PARTNONE && slice != D_SLICENONE) {
                        ret = zfs_probe(pa.fd, pool_guid);
                        if (ret == 0)
                                return (0);
                }
        }

        /* Probe each partition */
        ret = ioctl(pa.fd, DIOCGMEDIASIZE, &mediasz);
        if (ret == 0)
                ret = ioctl(pa.fd, DIOCGSECTORSIZE, &pa.secsz);
        if (ret == 0) {
                pa.devname = devname;
                pa.pool_guid = pool_guid;
                table = ptable_open(&pa, mediasz / pa.secsz, pa.secsz,
                    zfs_diskread);
                if (table != NULL) {
                        ptable_iterate(table, &pa, zfs_probe_partition);
                        ptable_close(table);
                }
        }
        close(pa.fd);
        if (pool_guid && *pool_guid == 0)
                ret = ENXIO;
        return (ret);
}

/*
 * Print information about ZFS pools
 */
static int
zfs_dev_print(int verbose)
{
        spa_t *spa;
        char line[80];
        int ret = 0;

        if (STAILQ_EMPTY(&zfs_pools))
                return (0);

        printf("%s devices:", zfs_dev.dv_name);
        if ((ret = pager_output("\n")) != 0)
                return (ret);

        if (verbose) {
                return (spa_all_status());
        }
        STAILQ_FOREACH(spa, &zfs_pools, spa_link) {
                snprintf(line, sizeof (line), "    zfs:%s\n", spa->spa_name);
                ret = pager_output(line);
                if (ret != 0)
                        break;
        }
        return (ret);
}

/*
 * Attempt to open the pool described by (dev) for use by (f).
 */
static int
zfs_dev_open(struct open_file *f, ...)
{
        va_list         args;
        struct zfs_devdesc      *dev;
        struct zfsmount *mount;
        spa_t           *spa;
        int             rv;

        va_start(args, f);
        dev = va_arg(args, struct zfs_devdesc *);
        va_end(args);

        if ((spa = spa_find_by_dev(dev)) == NULL)
                return (ENXIO);

        mount = malloc(sizeof (*mount));
        if (mount == NULL)
                rv = ENOMEM;
        else
                rv = zfs_mount(spa, dev->root_guid, mount);
        if (rv != 0) {
                free(mount);
                return (rv);
        }
        if (mount->objset.os_type != DMU_OST_ZFS) {
                printf("Unexpected object set type %ju\n",
                    (uintmax_t)mount->objset.os_type);
                free(mount);
                return (EIO);
        }
        f->f_devdata = mount;
        free(dev);
        return (0);
}

static int
zfs_dev_close(struct open_file *f)
{

        free(f->f_devdata);
        f->f_devdata = NULL;
        return (0);
}

static int
zfs_dev_strategy(void *devdata __unused, int rw __unused,
    daddr_t dblk __unused, size_t size __unused,
    char *buf __unused, size_t *rsize __unused)
{

        return (ENOSYS);
}

struct devsw zfs_dev = {
        .dv_name = "zfs",
        .dv_type = DEVT_ZFS,
        .dv_init = zfs_dev_init,
        .dv_strategy = zfs_dev_strategy,
        .dv_open = zfs_dev_open,
        .dv_close = zfs_dev_close,
        .dv_ioctl = noioctl,
        .dv_print = zfs_dev_print,
        .dv_cleanup = NULL
};

int
zfs_parsedev(struct zfs_devdesc *dev, const char *devspec, const char **path)
{
        static char     rootname[ZFS_MAXNAMELEN];
        static char     poolname[ZFS_MAXNAMELEN];
        spa_t           *spa;
        const char      *end;
        const char      *np;
        const char      *sep;
        int             rv;

        np = devspec;
        if (*np != ':')
                return (EINVAL);
        np++;
        end = strrchr(np, ':');
        if (end == NULL)
                return (EINVAL);
        sep = strchr(np, '/');
        if (sep == NULL || sep >= end)
                sep = end;
        memcpy(poolname, np, sep - np);
        poolname[sep - np] = '\0';
        if (sep < end) {
                sep++;
                memcpy(rootname, sep, end - sep);
                rootname[end - sep] = '\0';
        }
        else
                rootname[0] = '\0';

        spa = spa_find_by_name(poolname);
        if (!spa)
                return (ENXIO);
        dev->pool_guid = spa->spa_guid;
        rv = zfs_lookup_dataset(spa, rootname, &dev->root_guid);
        if (rv != 0)
                return (rv);
        if (path != NULL)
                *path = (*end == '\0') ? end : end + 1;
        dev->dd.d_dev = &zfs_dev;
        return (0);
}

char *
zfs_bootfs(void *zdev)
{
        static char             rootname[ZFS_MAXNAMELEN];
        static char             buf[2 * ZFS_MAXNAMELEN];
        struct zfs_devdesc      *dev = (struct zfs_devdesc *)zdev;
        uint64_t                objnum;
        spa_t                   *spa;
        int                     n;

        buf[0] = '\0';
        if (dev->dd.d_dev->dv_type != DEVT_ZFS)
                return (buf);

        spa = spa_find_by_guid(dev->pool_guid);
        if (spa == NULL) {
                printf("ZFS: can't find pool by guid\n");
                return (buf);
        }
        if (zfs_rlookup(spa, dev->root_guid, rootname)) {
                printf("ZFS: can't find filesystem by guid\n");
                return (buf);
        }
        if (zfs_lookup_dataset(spa, rootname, &objnum)) {
                printf("ZFS: can't find filesystem by name\n");
                return (buf);
        }

        /* Set the environment. */
        snprintf(buf, sizeof (buf), "%" PRIu64, dev->pool_guid);
        setenv("zfs-bootpool", buf, 1);
        snprintf(buf, sizeof (buf), "%" PRIu64, spa->spa_boot_vdev->v_guid);
        setenv("zfs-bootvdev", buf, 1);
        snprintf(buf, sizeof (buf), "%s/%" PRIu64, spa->spa_name, objnum);
        setenv("zfs-bootfs", buf, 1);
        if (spa->spa_boot_vdev->v_phys_path != NULL)
                setenv("bootpath", spa->spa_boot_vdev->v_phys_path, 1);
        if (spa->spa_boot_vdev->v_devid != NULL)
                setenv("diskdevid", spa->spa_boot_vdev->v_devid, 1);

        /*
         * Build the command line string. Once our kernel will read
         * the environment and we can stop caring about old kernels,
         * we can remove this part.
         */
        snprintf(buf, sizeof (buf), "zfs-bootfs=%s/%" PRIu64, spa->spa_name,
            objnum);
        n = strlen(buf);
        if (spa->spa_boot_vdev->v_phys_path != NULL) {
                snprintf(buf+n, sizeof (buf) - n, ",bootpath=\"%s\"",
                    spa->spa_boot_vdev->v_phys_path);
                n = strlen(buf);
        }
        if (spa->spa_boot_vdev->v_devid != NULL) {
                snprintf(buf+n, sizeof (buf) - n, ",diskdevid=\"%s\"",
                    spa->spa_boot_vdev->v_devid);
        }
        return (buf);
}

char *
zfs_fmtdev(void *vdev)
{
        static char             rootname[ZFS_MAXNAMELEN];
        static char             buf[2 * ZFS_MAXNAMELEN + 8];
        struct zfs_devdesc      *dev = (struct zfs_devdesc *)vdev;
        spa_t                   *spa;

        buf[0] = '\0';
        if (dev->dd.d_dev->dv_type != DEVT_ZFS)
                return (buf);

        /* Do we have any pools? */
        spa = STAILQ_FIRST(&zfs_pools);
        if (spa == NULL)
                return (buf);

        if (dev->pool_guid == 0)
                dev->pool_guid = spa->spa_guid;
        else
                spa = spa_find_by_guid(dev->pool_guid);

        if (spa == NULL) {
                printf("ZFS: can't find pool by guid\n");
                return (buf);
        }
        if (dev->root_guid == 0 && zfs_get_root(spa, &dev->root_guid)) {
                printf("ZFS: can't find root filesystem\n");
                return (buf);
        }
        if (zfs_rlookup(spa, dev->root_guid, rootname)) {
                printf("ZFS: can't find filesystem by guid\n");
                return (buf);
        }

        if (rootname[0] == '\0')
                snprintf(buf, sizeof (buf), "%s:%s:", dev->dd.d_dev->dv_name,
                    spa->spa_name);
        else
                snprintf(buf, sizeof (buf), "%s:%s/%s:", dev->dd.d_dev->dv_name,
                    spa->spa_name, rootname);
        return (buf);
}

int
zfs_list(const char *name)
{
        static char     poolname[ZFS_MAXNAMELEN];
        uint64_t        objid;
        spa_t           *spa;
        const char      *dsname;
        int             len;
        int             rv;

        len = strlen(name);
        dsname = strchr(name, '/');
        if (dsname != NULL) {
                len = dsname - name;
                dsname++;
        } else
                dsname = "";
        memcpy(poolname, name, len);
        poolname[len] = '\0';

        spa = spa_find_by_name(poolname);
        if (!spa)
                return (ENXIO);
        rv = zfs_lookup_dataset(spa, dsname, &objid);
        if (rv != 0)
                return (rv);

        return (zfs_list_dataset(spa, objid));
}