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libzfs_changelist.c

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

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * Portions Copyright 2007 Ramprakash Jelari
 */

#include <libintl.h>
#include <libuutil.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <zone.h>

#include <libzfs.h>

#include "libzfs_impl.h"

/*
 * Structure to keep track of dataset state.  Before changing the 'sharenfs' or
 * 'mountpoint' property, we record whether the filesystem was previously
 * mounted/shared.  This prior state dictates whether we remount/reshare the
 * dataset after the property has been changed.
 *
 * The interface consists of the following sequence of functions:
 *
 *    changelist_gather()
 *    changelist_prefix()
 *    < change property >
 *    changelist_postfix()
 *    changelist_free()
 *
 * Other interfaces:
 *
 * changelist_remove() - remove a node from a gathered list
 * changelist_rename() - renames all datasets appropriately when doing a rename
 * changelist_unshare() - unshares all the nodes in a given changelist
 * changelist_haszonedchild() - check if there is any child exported to
 *                      a local zone
 */
typedef struct prop_changenode {
      zfs_handle_t            *cn_handle;
      int               cn_shared;
      int               cn_mounted;
      int               cn_zoned;
      boolean_t         cn_needpost;      /* is postfix() needed? */
      uu_list_node_t          cn_listnode;
} prop_changenode_t;

struct prop_changelist {
      zfs_prop_t        cl_prop;
      zfs_prop_t        cl_realprop;
      zfs_prop_t        cl_shareprop;  /* used with sharenfs/sharesmb */
      uu_list_pool_t          *cl_pool;
      uu_list_t         *cl_list;
      boolean_t         cl_waslegacy;
      boolean_t         cl_allchildren;
      boolean_t         cl_alldependents;
      int               cl_mflags;  /* Mount flags */
      int               cl_gflags;  /* Gather request flags */
      boolean_t         cl_haszonedchild;
      boolean_t         cl_sorted;
};

/*
 * If the property is 'mountpoint', go through and unmount filesystems as
 * necessary.  We don't do the same for 'sharenfs', because we can just re-share
 * with different options without interrupting service. We do handle 'sharesmb'
 * since there may be old resource names that need to be removed.
 */
int
changelist_prefix(prop_changelist_t *clp)
{
      prop_changenode_t *cn;
      int ret = 0;

      if (clp->cl_prop != ZFS_PROP_MOUNTPOINT &&
          clp->cl_prop != ZFS_PROP_SHARESMB)
            return (0);

      for (cn = uu_list_first(clp->cl_list); cn != NULL;
          cn = uu_list_next(clp->cl_list, cn)) {

            /* if a previous loop failed, set the remaining to false */
            if (ret == -1) {
                  cn->cn_needpost = B_FALSE;
                  continue;
            }

            /*
             * If we are in the global zone, but this dataset is exported
             * to a local zone, do nothing.
             */
            if (getzoneid() == GLOBAL_ZONEID && cn->cn_zoned)
                  continue;

            if (ZFS_IS_VOLUME(cn->cn_handle)) {
                  switch (clp->cl_realprop) {
                  case ZFS_PROP_NAME:
                        /*
                         * If this was a rename, unshare the zvol, and
                         * remove the /dev/zvol links.
                         */
                        (void) zfs_unshare_iscsi(cn->cn_handle);

                        if (zvol_remove_link(cn->cn_handle->zfs_hdl,
                            cn->cn_handle->zfs_name) != 0) {
                              ret = -1;
                              cn->cn_needpost = B_FALSE;
                              (void) zfs_share_iscsi(cn->cn_handle);
                        }
                        break;

                  case ZFS_PROP_VOLSIZE:
                        /*
                         * If this was a change to the volume size, we
                         * need to unshare and reshare the volume.
                         */
                        (void) zfs_unshare_iscsi(cn->cn_handle);
                        break;
                  }
            } else {
                  /*
                   * Do the property specific processing.
                   */
                  switch (clp->cl_prop) {
                  case ZFS_PROP_MOUNTPOINT:
                        if (zfs_unmount(cn->cn_handle, NULL,
                            clp->cl_mflags) != 0) {
                              ret = -1;
                              cn->cn_needpost = B_FALSE;
                        }
                        break;
                  case ZFS_PROP_SHARESMB:
                        (void) zfs_unshare_smb(cn->cn_handle, NULL);
                        break;
                  }
            }
      }

      if (ret == -1)
            (void) changelist_postfix(clp);

      return (ret);
}

/*
 * If the property is 'mountpoint' or 'sharenfs', go through and remount and/or
 * reshare the filesystems as necessary.  In changelist_gather() we recorded
 * whether the filesystem was previously shared or mounted.  The action we take
 * depends on the previous state, and whether the value was previously 'legacy'.
 * For non-legacy properties, we only remount/reshare the filesystem if it was
 * previously mounted/shared.  Otherwise, we always remount/reshare the
 * filesystem.
 */
int
changelist_postfix(prop_changelist_t *clp)
{
      prop_changenode_t *cn;
      char shareopts[ZFS_MAXPROPLEN];
      int errors = 0;
      libzfs_handle_t *hdl;

      /*
       * If we're changing the mountpoint, attempt to destroy the underlying
       * mountpoint.  All other datasets will have inherited from this dataset
       * (in which case their mountpoints exist in the filesystem in the new
       * location), or have explicit mountpoints set (in which case they won't
       * be in the changelist).
       */
      if ((cn = uu_list_last(clp->cl_list)) == NULL)
            return (0);

      if (clp->cl_prop == ZFS_PROP_MOUNTPOINT)
            remove_mountpoint(cn->cn_handle);

      /*
       * It is possible that the changelist_prefix() used libshare
       * to unshare some entries. Since libshare caches data, an
       * attempt to reshare during postfix can fail unless libshare
       * is uninitialized here so that it will reinitialize later.
       */
      if (cn->cn_handle != NULL) {
            hdl = cn->cn_handle->zfs_hdl;
            assert(hdl != NULL);
            zfs_uninit_libshare(hdl);
      }

      /*
       * We walk the datasets in reverse, because we want to mount any parent
       * datasets before mounting the children.  We walk all datasets even if
       * there are errors.
       */
      for (cn = uu_list_last(clp->cl_list); cn != NULL;
          cn = uu_list_prev(clp->cl_list, cn)) {

            boolean_t sharenfs;
            boolean_t sharesmb;

            /*
             * If we are in the global zone, but this dataset is exported
             * to a local zone, do nothing.
             */
            if (getzoneid() == GLOBAL_ZONEID && cn->cn_zoned)
                  continue;

            /* Only do post-processing if it's required */
            if (!cn->cn_needpost)
                  continue;
            cn->cn_needpost = B_FALSE;

            zfs_refresh_properties(cn->cn_handle);

            if (ZFS_IS_VOLUME(cn->cn_handle)) {
                  /*
                   * If we're doing a rename, recreate the /dev/zvol
                   * links.
                   */
                  if (clp->cl_realprop == ZFS_PROP_NAME &&
                      zvol_create_link(cn->cn_handle->zfs_hdl,
                      cn->cn_handle->zfs_name) != 0) {
                        errors++;
                  } else if (cn->cn_shared ||
                      clp->cl_prop == ZFS_PROP_SHAREISCSI) {
                        if (zfs_prop_get(cn->cn_handle,
                            ZFS_PROP_SHAREISCSI, shareopts,
                            sizeof (shareopts), NULL, NULL, 0,
                            B_FALSE) == 0 &&
                            strcmp(shareopts, "off") == 0) {
                              errors +=
                                  zfs_unshare_iscsi(cn->cn_handle);
                        } else {
                              errors +=
                                  zfs_share_iscsi(cn->cn_handle);
                        }
                  }

                  continue;
            }

            /*
             * Remount if previously mounted or mountpoint was legacy,
             * or sharenfs or sharesmb  property is set.
             */
            sharenfs = ((zfs_prop_get(cn->cn_handle, ZFS_PROP_SHARENFS,
                shareopts, sizeof (shareopts), NULL, NULL, 0,
                B_FALSE) == 0) && (strcmp(shareopts, "off") != 0));

            sharesmb = ((zfs_prop_get(cn->cn_handle, ZFS_PROP_SHARESMB,
                shareopts, sizeof (shareopts), NULL, NULL, 0,
                B_FALSE) == 0) && (strcmp(shareopts, "off") != 0));

            if ((cn->cn_mounted || clp->cl_waslegacy || sharenfs ||
                sharesmb) && !zfs_is_mounted(cn->cn_handle, NULL) &&
                zfs_mount(cn->cn_handle, NULL, 0) != 0)
                  errors++;

            /*
             * We always re-share even if the filesystem is currently
             * shared, so that we can adopt any new options.
             */
            if (sharenfs)
                  errors += zfs_share_nfs(cn->cn_handle);
            else if (cn->cn_shared || clp->cl_waslegacy)
                  errors += zfs_unshare_nfs(cn->cn_handle, NULL);
            if (sharesmb)
                  errors += zfs_share_smb(cn->cn_handle);
            else if (cn->cn_shared || clp->cl_waslegacy)
                  errors += zfs_unshare_smb(cn->cn_handle, NULL);
      }

      return (errors ? -1 : 0);
}

/*
 * Is this "dataset" a child of "parent"?
 */
boolean_t
isa_child_of(const char *dataset, const char *parent)
{
      int len;

      len = strlen(parent);

      if (strncmp(dataset, parent, len) == 0 &&
          (dataset[len] == '@' || dataset[len] == '/' ||
          dataset[len] == '\0'))
            return (B_TRUE);
      else
            return (B_FALSE);

}

/*
 * If we rename a filesystem, child filesystem handles are no longer valid
 * since we identify each dataset by its name in the ZFS namespace.  As a
 * result, we have to go through and fix up all the names appropriately.  We
 * could do this automatically if libzfs kept track of all open handles, but
 * this is a lot less work.
 */
void
changelist_rename(prop_changelist_t *clp, const char *src, const char *dst)
{
      prop_changenode_t *cn;
      char newname[ZFS_MAXNAMELEN];

      for (cn = uu_list_first(clp->cl_list); cn != NULL;
          cn = uu_list_next(clp->cl_list, cn)) {
            /*
             * Do not rename a clone that's not in the source hierarchy.
             */
            if (!isa_child_of(cn->cn_handle->zfs_name, src))
                  continue;

            /*
             * Destroy the previous mountpoint if needed.
             */
            remove_mountpoint(cn->cn_handle);

            (void) strlcpy(newname, dst, sizeof (newname));
            (void) strcat(newname, cn->cn_handle->zfs_name + strlen(src));

            (void) strlcpy(cn->cn_handle->zfs_name, newname,
                sizeof (cn->cn_handle->zfs_name));
      }
}

/*
 * Given a gathered changelist for the 'sharenfs' or 'sharesmb' property,
 * unshare all the datasets in the list.
 */
int
changelist_unshare(prop_changelist_t *clp, zfs_share_proto_t *proto)
{
      prop_changenode_t *cn;
      int ret = 0;

      if (clp->cl_prop != ZFS_PROP_SHARENFS &&
          clp->cl_prop != ZFS_PROP_SHARESMB)
            return (0);

      for (cn = uu_list_first(clp->cl_list); cn != NULL;
          cn = uu_list_next(clp->cl_list, cn)) {
            if (zfs_unshare_proto(cn->cn_handle, NULL, proto) != 0)
                  ret = -1;
      }

      return (ret);
}

/*
 * Check if there is any child exported to a local zone in a given changelist.
 * This information has already been recorded while gathering the changelist
 * via changelist_gather().
 */
int
changelist_haszonedchild(prop_changelist_t *clp)
{
      return (clp->cl_haszonedchild);
}

/*
 * Remove a node from a gathered list.
 */
void
changelist_remove(prop_changelist_t *clp, const char *name)
{
      prop_changenode_t *cn;

      for (cn = uu_list_first(clp->cl_list); cn != NULL;
          cn = uu_list_next(clp->cl_list, cn)) {

            if (strcmp(cn->cn_handle->zfs_name, name) == 0) {
                  uu_list_remove(clp->cl_list, cn);
                  zfs_close(cn->cn_handle);
                  free(cn);
                  return;
            }
      }
}

/*
 * Release any memory associated with a changelist.
 */
void
changelist_free(prop_changelist_t *clp)
{
      prop_changenode_t *cn;
      void *cookie;

      if (clp->cl_list) {
            cookie = NULL;
            while ((cn = uu_list_teardown(clp->cl_list, &cookie)) != NULL) {
                  zfs_close(cn->cn_handle);
                  free(cn);
            }

            uu_list_destroy(clp->cl_list);
      }
      if (clp->cl_pool)
            uu_list_pool_destroy(clp->cl_pool);

      free(clp);
}

static int
change_one(zfs_handle_t *zhp, void *data)
{
      prop_changelist_t *clp = data;
      char property[ZFS_MAXPROPLEN];
      char where[64];
      prop_changenode_t *cn;
      zprop_source_t sourcetype;
      zprop_source_t share_sourcetype;

      /*
       * We only want to unmount/unshare those filesystems that may inherit
       * from the target filesystem.  If we find any filesystem with a
       * locally set mountpoint, we ignore any children since changing the
       * property will not affect them.  If this is a rename, we iterate
       * over all children regardless, since we need them unmounted in
       * order to do the rename.  Also, if this is a volume and we're doing
       * a rename, then always add it to the changelist.
       */

      if (!(ZFS_IS_VOLUME(zhp) && clp->cl_realprop == ZFS_PROP_NAME) &&
          zfs_prop_get(zhp, clp->cl_prop, property,
          sizeof (property), &sourcetype, where, sizeof (where),
          B_FALSE) != 0) {
            zfs_close(zhp);
            return (0);
      }

      /*
       * If we are "watching" sharenfs or sharesmb
       * then check out the companion property which is tracked
       * in cl_shareprop
       */
      if (clp->cl_shareprop != ZPROP_INVAL &&
          zfs_prop_get(zhp, clp->cl_shareprop, property,
          sizeof (property), &share_sourcetype, where, sizeof (where),
          B_FALSE) != 0) {
            zfs_close(zhp);
            return (0);
      }

      if (clp->cl_alldependents || clp->cl_allchildren ||
          sourcetype == ZPROP_SRC_DEFAULT ||
          sourcetype == ZPROP_SRC_INHERITED ||
          (clp->cl_shareprop != ZPROP_INVAL &&
          (share_sourcetype == ZPROP_SRC_DEFAULT ||
          share_sourcetype == ZPROP_SRC_INHERITED))) {
            if ((cn = zfs_alloc(zfs_get_handle(zhp),
                sizeof (prop_changenode_t))) == NULL) {
                  zfs_close(zhp);
                  return (-1);
            }

            cn->cn_handle = zhp;
            cn->cn_mounted = (clp->cl_gflags & CL_GATHER_MOUNT_ALWAYS) ||
                zfs_is_mounted(zhp, NULL);
            cn->cn_shared = zfs_is_shared(zhp);
            cn->cn_zoned = zfs_prop_get_int(zhp, ZFS_PROP_ZONED);
            cn->cn_needpost = B_TRUE;

            /* Indicate if any child is exported to a local zone. */
            if (getzoneid() == GLOBAL_ZONEID && cn->cn_zoned)
                  clp->cl_haszonedchild = B_TRUE;

            uu_list_node_init(cn, &cn->cn_listnode, clp->cl_pool);

            if (clp->cl_sorted) {
                  uu_list_index_t idx;

                  (void) uu_list_find(clp->cl_list, cn, NULL,
                      &idx);
                  uu_list_insert(clp->cl_list, cn, idx);
            } else {
                  ASSERT(!clp->cl_alldependents);
                  verify(uu_list_insert_before(clp->cl_list,
                      uu_list_first(clp->cl_list), cn) == 0);
            }

            if (!clp->cl_alldependents)
                  return (zfs_iter_children(zhp, change_one, data));
      } else {
            zfs_close(zhp);
      }

      return (0);
}

/*ARGSUSED*/
static int
compare_mountpoints(const void *a, const void *b, void *unused)
{
      const prop_changenode_t *ca = a;
      const prop_changenode_t *cb = b;

      char mounta[MAXPATHLEN];
      char mountb[MAXPATHLEN];

      boolean_t hasmounta, hasmountb;

      /*
       * When unsharing or unmounting filesystems, we need to do it in
       * mountpoint order.  This allows the user to have a mountpoint
       * hierarchy that is different from the dataset hierarchy, and still
       * allow it to be changed.  However, if either dataset doesn't have a
       * mountpoint (because it is a volume or a snapshot), we place it at the
       * end of the list, because it doesn't affect our change at all.
       */
      hasmounta = (zfs_prop_get(ca->cn_handle, ZFS_PROP_MOUNTPOINT, mounta,
          sizeof (mounta), NULL, NULL, 0, B_FALSE) == 0);
      hasmountb = (zfs_prop_get(cb->cn_handle, ZFS_PROP_MOUNTPOINT, mountb,
          sizeof (mountb), NULL, NULL, 0, B_FALSE) == 0);

      if (!hasmounta && hasmountb)
            return (-1);
      else if (hasmounta && !hasmountb)
            return (1);
      else if (!hasmounta && !hasmountb)
            return (0);
      else
            return (strcmp(mountb, mounta));
}

/*
 * Given a ZFS handle and a property, construct a complete list of datasets
 * that need to be modified as part of this process.  For anything but the
 * 'mountpoint' and 'sharenfs' properties, this just returns an empty list.
 * Otherwise, we iterate over all children and look for any datasets that
 * inherit the property.  For each such dataset, we add it to the list and
 * mark whether it was shared beforehand.
 */
prop_changelist_t *
changelist_gather(zfs_handle_t *zhp, zfs_prop_t prop, int gather_flags,
    int mnt_flags)
{
      prop_changelist_t *clp;
      prop_changenode_t *cn;
      zfs_handle_t *temp;
      char property[ZFS_MAXPROPLEN];
      uu_compare_fn_t *compare = NULL;

      if ((clp = zfs_alloc(zhp->zfs_hdl, sizeof (prop_changelist_t))) == NULL)
            return (NULL);

      /*
       * For mountpoint-related tasks, we want to sort everything by
       * mountpoint, so that we mount and unmount them in the appropriate
       * order, regardless of their position in the hierarchy.
       */
      if (prop == ZFS_PROP_NAME || prop == ZFS_PROP_ZONED ||
          prop == ZFS_PROP_MOUNTPOINT || prop == ZFS_PROP_SHARENFS ||
          prop == ZFS_PROP_SHARESMB) {
            compare = compare_mountpoints;
            clp->cl_sorted = B_TRUE;
      }

      clp->cl_pool = uu_list_pool_create("changelist_pool",
          sizeof (prop_changenode_t),
          offsetof(prop_changenode_t, cn_listnode),
          compare, 0);
      if (clp->cl_pool == NULL) {
            assert(uu_error() == UU_ERROR_NO_MEMORY);
            (void) zfs_error(zhp->zfs_hdl, EZFS_NOMEM, "internal error");
            changelist_free(clp);
            return (NULL);
      }

      clp->cl_list = uu_list_create(clp->cl_pool, NULL,
          clp->cl_sorted ? UU_LIST_SORTED : 0);
      clp->cl_gflags = gather_flags;
      clp->cl_mflags = mnt_flags;

      if (clp->cl_list == NULL) {
            assert(uu_error() == UU_ERROR_NO_MEMORY);
            (void) zfs_error(zhp->zfs_hdl, EZFS_NOMEM, "internal error");
            changelist_free(clp);
            return (NULL);
      }

      /*
       * If this is a rename or the 'zoned' property, we pretend we're
       * changing the mountpoint and flag it so we can catch all children in
       * change_one().
       *
       * Flag cl_alldependents to catch all children plus the dependents
       * (clones) that are not in the hierarchy.
       */
      if (prop == ZFS_PROP_NAME) {
            clp->cl_prop = ZFS_PROP_MOUNTPOINT;
            clp->cl_alldependents = B_TRUE;
      } else if (prop == ZFS_PROP_ZONED) {
            clp->cl_prop = ZFS_PROP_MOUNTPOINT;
            clp->cl_allchildren = B_TRUE;
      } else if (prop == ZFS_PROP_CANMOUNT) {
            clp->cl_prop = ZFS_PROP_MOUNTPOINT;
      } else if (prop == ZFS_PROP_VOLSIZE) {
            clp->cl_prop = ZFS_PROP_MOUNTPOINT;
      } else if (prop == ZFS_PROP_VERSION) {
            clp->cl_prop = ZFS_PROP_MOUNTPOINT;
      } else {
            clp->cl_prop = prop;
      }
      clp->cl_realprop = prop;

      if (clp->cl_prop != ZFS_PROP_MOUNTPOINT &&
          clp->cl_prop != ZFS_PROP_SHARENFS &&
          clp->cl_prop != ZFS_PROP_SHARESMB &&
          clp->cl_prop != ZFS_PROP_SHAREISCSI)
            return (clp);

      /*
       * If watching SHARENFS or SHARESMB then
       * also watch its companion property.
       */
      if (clp->cl_prop == ZFS_PROP_SHARENFS)
            clp->cl_shareprop = ZFS_PROP_SHARESMB;
      else if (clp->cl_prop == ZFS_PROP_SHARESMB)
            clp->cl_shareprop = ZFS_PROP_SHARENFS;

      if (clp->cl_alldependents) {
            if (zfs_iter_dependents(zhp, B_TRUE, change_one, clp) != 0) {
                  changelist_free(clp);
                  return (NULL);
            }
      } else if (zfs_iter_children(zhp, change_one, clp) != 0) {
            changelist_free(clp);
            return (NULL);
      }

      /*
       * We have to re-open ourselves because we auto-close all the handles
       * and can't tell the difference.
       */
      if ((temp = zfs_open(zhp->zfs_hdl, zfs_get_name(zhp),
          ZFS_TYPE_DATASET)) == NULL) {
            changelist_free(clp);
            return (NULL);
      }

      /*
       * Always add ourself to the list.  We add ourselves to the end so that
       * we're the last to be unmounted.
       */
      if ((cn = zfs_alloc(zhp->zfs_hdl,
          sizeof (prop_changenode_t))) == NULL) {
            zfs_close(temp);
            changelist_free(clp);
            return (NULL);
      }

      cn->cn_handle = temp;
      cn->cn_mounted = (clp->cl_gflags & CL_GATHER_MOUNT_ALWAYS) ||
          zfs_is_mounted(temp, NULL);
      cn->cn_shared = zfs_is_shared(temp);
      cn->cn_zoned = zfs_prop_get_int(zhp, ZFS_PROP_ZONED);
      cn->cn_needpost = B_TRUE;

      uu_list_node_init(cn, &cn->cn_listnode, clp->cl_pool);
      if (clp->cl_sorted) {
            uu_list_index_t idx;
            (void) uu_list_find(clp->cl_list, cn, NULL, &idx);
            uu_list_insert(clp->cl_list, cn, idx);
      } else {
            verify(uu_list_insert_after(clp->cl_list,
                uu_list_last(clp->cl_list), cn) == 0);
      }

      /*
       * If the mountpoint property was previously 'legacy', or 'none',
       * record it as the behavior of changelist_postfix() will be different.
       */
      if ((clp->cl_prop == ZFS_PROP_MOUNTPOINT) &&
          (zfs_prop_get(zhp, prop, property, sizeof (property),
          NULL, NULL, 0, B_FALSE) == 0 &&
          (strcmp(property, "legacy") == 0 ||
          strcmp(property, "none") == 0))) {
            /*
             * do not automatically mount ex-legacy datasets if
             * we specifically set canmount to noauto
             */
            if (zfs_prop_get_int(zhp, ZFS_PROP_CANMOUNT) !=
                ZFS_CANMOUNT_NOAUTO)
                  clp->cl_waslegacy = B_TRUE;
      }

      return (clp);
}

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