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[Samba.git] / source3 / locking / share_mode_lock.c

/*
   Unix SMB/CIFS implementation.
   Locking functions
   Copyright (C) Andrew Tridgell 1992-2000
   Copyright (C) Jeremy Allison 1992-2006
   Copyright (C) Volker Lendecke 2005

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.

   Revision History:

   12 aug 96: Erik.Devriendt@te6.siemens.be
   added support for shared memory implementation of share mode locking

   May 1997. Jeremy Allison (jallison@whistle.com). Modified share mode
   locking to deal with multiple share modes per open file.

   September 1997. Jeremy Allison (jallison@whistle.com). Added oplock
   support.

   rewritten completely to use new tdb code. Tridge, Dec '99

   Added POSIX locking support. Jeremy Allison (jeremy@valinux.com), Apr. 2000.
   Added Unix Extensions POSIX locking support. Jeremy Allison Mar 2006.
*/

#include "includes.h"
#include "lib/util/time_basic.h"
#include "system/filesys.h"
#include "lib/util/server_id.h"
#include "share_mode_lock_private.h"
struct share_mode_lock {
        struct file_id id;
        struct share_mode_data *cached_data;
};
#define SHARE_MODE_ENTRY_PREPARE_STATE_LCK_SPACE 1
#include "share_mode_lock.h"
#include "locking/proto.h"
#include "smbd/globals.h"
#include "dbwrap/dbwrap.h"
#include "dbwrap/dbwrap_open.h"
#include "dbwrap/dbwrap_private.h"
#include "../libcli/security/security.h"
#include "serverid.h"
#include "messages.h"
#include "util_tdb.h"
#include "../librpc/gen_ndr/ndr_open_files.h"
#include "source3/lib/dbwrap/dbwrap_watch.h"
#include "locking/leases_db.h"
#include "../lib/util/memcache.h"
#include "lib/util/tevent_ntstatus.h"
#include "g_lock.h"
#include "smbd/fd_handle.h"
#include "lib/global_contexts.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_LOCKING

#define DBG_GET_SHARE_MODE_LOCK(__status, ...) \
        DBG_PREFIX( \
                NT_STATUS_EQUAL(__status, NT_STATUS_NOT_FOUND) ? \
                DBGLVL_DEBUG : DBGLVL_ERR, \
                (__VA_ARGS__))

/* the locking database handle */
static struct g_lock_ctx *lock_ctx;
static struct g_lock_lock_cb_state *current_share_mode_glck = NULL;

static bool share_mode_g_lock_within_cb(TDB_DATA key);

static NTSTATUS share_mode_g_lock_dump(TDB_DATA key,
                                       void (*fn)(struct server_id exclusive,
                                                  size_t num_shared,
                                                  const struct server_id *shared,
                                                  const uint8_t *data,
                                                  size_t datalen,
                                                  void *private_data),
                                       void *private_data)
{
        if (share_mode_g_lock_within_cb(key)) {
                return g_lock_lock_cb_dump(current_share_mode_glck,
                                           fn, private_data);
        }

        return g_lock_dump(lock_ctx, key, fn, private_data);
}

static NTSTATUS share_mode_g_lock_writev(TDB_DATA key,
                                         const TDB_DATA *dbufs,
                                         size_t num_dbufs)
{
        if (share_mode_g_lock_within_cb(key)) {
                return g_lock_lock_cb_writev(current_share_mode_glck,
                                             dbufs, num_dbufs);
        }

        return g_lock_writev_data(lock_ctx, key, dbufs, num_dbufs);
}

static bool locking_init_internal(bool read_only)
{
        struct db_context *backend;
        char *db_path;

        brl_init(read_only);

        if (lock_ctx != NULL) {
                return True;
        }

        db_path = lock_path(talloc_tos(), "locking.tdb");
        if (db_path == NULL) {
                return false;
        }

        backend = db_open(NULL, db_path,
                          SMB_OPEN_DATABASE_TDB_HASH_SIZE,
                          TDB_DEFAULT|
                          TDB_VOLATILE|
                          TDB_CLEAR_IF_FIRST|
                          TDB_INCOMPATIBLE_HASH|
                          TDB_SEQNUM,
                          read_only?O_RDONLY:O_RDWR|O_CREAT, 0644,
                          DBWRAP_LOCK_ORDER_NONE,
                          DBWRAP_FLAG_NONE);
        TALLOC_FREE(db_path);
        if (!backend) {
                DEBUG(0,("ERROR: Failed to initialise locking database\n"));
                return False;
        }

        lock_ctx = g_lock_ctx_init_backend(
                NULL, global_messaging_context(), &backend);
        if (lock_ctx == NULL) {
                TALLOC_FREE(backend);
                return false;
        }
        g_lock_set_lock_order(lock_ctx, DBWRAP_LOCK_ORDER_1);

        if (!posix_locking_init(read_only)) {
                TALLOC_FREE(lock_ctx);
                return False;
        }

        return True;
}

bool locking_init(void)
{
        return locking_init_internal(false);
}

bool locking_init_readonly(void)
{
        return locking_init_internal(true);
}

/*******************************************************************
 Deinitialize the share_mode management.
******************************************************************/

bool locking_end(void)
{
        brl_shutdown();
        TALLOC_FREE(lock_ctx);
        return true;
}

/*******************************************************************
 Form a static locking key for a dev/inode pair.
******************************************************************/

static TDB_DATA locking_key(const struct file_id *id)
{
        return make_tdb_data((const uint8_t *)id, sizeof(*id));
}

/*******************************************************************
 Share mode cache utility functions that store/delete/retrieve
 entries from memcache.

 For now share the statcache (global cache) memory space. If
 a lock record gets orphaned (which shouldn't happen as we're
 using the same locking_key data as lookup) it will eventually
 fall out of the cache via the normal LRU trim mechanism. If
 necessary we can always make this a separate (smaller) cache.
******************************************************************/

static DATA_BLOB memcache_key(const struct file_id *id)
{
        return data_blob_const((const void *)id, sizeof(*id));
}

static void share_mode_memcache_store(struct share_mode_data *d)
{
        const DATA_BLOB key = memcache_key(&d->id);
        struct file_id_buf idbuf;

        DBG_DEBUG("stored entry for file %s epoch %"PRIx64" key %s\n",
                  d->base_name,
                  d->unique_content_epoch,
                  file_id_str_buf(d->id, &idbuf));

        /* Ensure everything stored in the cache is pristine. */
        SMB_ASSERT(!d->modified);
        SMB_ASSERT(!d->not_stored);

        /*
         * Ensure the memory going into the cache
         * doesn't have a destructor so it can be
         * cleanly evicted by the memcache LRU
         * mechanism.
         */
        talloc_set_destructor(d, NULL);

        /* Cache will own d after this call. */
        memcache_add_talloc(NULL,
                        SHARE_MODE_LOCK_CACHE,
                        key,
                        &d);
}

/*
 * NB. We use ndr_pull_hyper on a stack-created
 * struct ndr_pull with no talloc allowed, as we
 * need this to be really fast as an ndr-peek into
 * the first 10 bytes of the blob.
 */

static enum ndr_err_code get_share_mode_blob_header(
        const uint8_t *buf, size_t buflen, uint64_t *pepoch, uint16_t *pflags)
{
        struct ndr_pull ndr = {
                .data = discard_const_p(uint8_t, buf),
                .data_size = buflen,
        };
        NDR_CHECK(ndr_pull_hyper(&ndr, NDR_SCALARS, pepoch));
        NDR_CHECK(ndr_pull_uint16(&ndr, NDR_SCALARS, pflags));
        return NDR_ERR_SUCCESS;
}

static int share_mode_data_nofree_destructor(struct share_mode_data *d)
{
        return -1;
}

static struct share_mode_data *share_mode_memcache_fetch(
        TALLOC_CTX *mem_ctx,
        struct file_id id,
        const uint8_t *buf,
        size_t buflen)
{
        const DATA_BLOB key = memcache_key(&id);
        enum ndr_err_code ndr_err;
        struct share_mode_data *d;
        uint64_t unique_content_epoch;
        uint16_t flags;
        void *ptr;
        struct file_id_buf idbuf;

        ptr = memcache_lookup_talloc(NULL,
                        SHARE_MODE_LOCK_CACHE,
                        key);
        if (ptr == NULL) {
                DBG_DEBUG("failed to find entry for key %s\n",
                          file_id_str_buf(id, &idbuf));
                return NULL;
        }
        /* sequence number key is at start of blob. */
        ndr_err = get_share_mode_blob_header(
                buf, buflen, &unique_content_epoch, &flags);
        if (ndr_err != NDR_ERR_SUCCESS) {
                /* Bad blob. Remove entry. */
                DBG_DEBUG("bad blob %u key %s\n",
                          (unsigned int)ndr_err,
                          file_id_str_buf(id, &idbuf));
                memcache_delete(NULL,
                        SHARE_MODE_LOCK_CACHE,
                        key);
                return NULL;
        }

        d = (struct share_mode_data *)ptr;
        if (d->unique_content_epoch != unique_content_epoch) {
                DBG_DEBUG("epoch changed (cached %"PRIx64") (new %"PRIx64") "
                          "for key %s\n",
                          d->unique_content_epoch,
                          unique_content_epoch,
                          file_id_str_buf(id, &idbuf));
                /* Cache out of date. Remove entry. */
                memcache_delete(NULL,
                        SHARE_MODE_LOCK_CACHE,
                        key);
                return NULL;
        }

        /* Move onto mem_ctx. */
        d = talloc_move(mem_ctx, &ptr);

        /*
         * Now we own d, prevent the cache from freeing it
         * when we delete the entry.
         */
        talloc_set_destructor(d, share_mode_data_nofree_destructor);

        /* Remove from the cache. We own it now. */
        memcache_delete(NULL,
                        SHARE_MODE_LOCK_CACHE,
                        key);

        /* And reset the destructor to none. */
        talloc_set_destructor(d, NULL);

        DBG_DEBUG("fetched entry for file %s epoch %"PRIx64" key %s\n",
                  d->base_name,
                  d->unique_content_epoch,
                  file_id_str_buf(id, &idbuf));

        return d;
}

/*
 * 132 is the sizeof an ndr-encoded struct share_mode_entry_buf.
 * Reading/writing entries will immediately error out if this
 * size differs (push/pull is done without allocs).
 */

struct share_mode_entry_buf {
        uint8_t buf[132];
};
#define SHARE_MODE_ENTRY_SIZE (sizeof(struct share_mode_entry_buf))

static bool share_mode_entry_put(
        const struct share_mode_entry *e,
        struct share_mode_entry_buf *dst)
{
        DATA_BLOB blob = { .data = dst->buf, .length = sizeof(dst->buf) };
        enum ndr_err_code ndr_err;

        if (DEBUGLEVEL>=10) {
                DBG_DEBUG("share_mode_entry:\n");
                NDR_PRINT_DEBUG(share_mode_entry, discard_const_p(void, e));
        }

        ndr_err = ndr_push_struct_into_fixed_blob(
                &blob,
                e,
                (ndr_push_flags_fn_t)ndr_push_share_mode_entry);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                DBG_WARNING("ndr_push_share_mode_entry failed: %s\n",
                            ndr_errstr(ndr_err));
                return false;
        }

        return true;
}

static bool share_mode_entry_get(
        const uint8_t ptr[SHARE_MODE_ENTRY_SIZE], struct share_mode_entry *e)
{
        enum ndr_err_code ndr_err = NDR_ERR_SUCCESS;
        DATA_BLOB blob = {
                .data = discard_const_p(uint8_t, ptr),
                .length = SHARE_MODE_ENTRY_SIZE,
        };

        ndr_err = ndr_pull_struct_blob_all_noalloc(
                &blob, e, (ndr_pull_flags_fn_t)ndr_pull_share_mode_entry);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                DBG_WARNING("ndr_pull_share_mode_entry failed\n");
                return false;
        }
        return true;
}

/*
 * locking.tdb records consist of
 *
 * uint32_t share_mode_data_len
 * uint8_t [share_mode_data]       This is struct share_mode_data in NDR
 *
 * 0 [SHARE_MODE_ENTRY_SIZE]       Sorted array of share modes,
 * 1 [SHARE_MODE_ENTRY_SIZE]       filling up the rest of the data in the
 * 2 [SHARE_MODE_ENTRY_SIZE]       g_lock.c maintained record in locking.tdb
 */

struct locking_tdb_data {
        const uint8_t *share_mode_data_buf;
        size_t share_mode_data_len;
        const uint8_t *share_entries;
        size_t num_share_entries;
};

static bool locking_tdb_data_get(
        struct locking_tdb_data *data, const uint8_t *buf, size_t buflen)
{
        uint32_t share_mode_data_len, share_entries_len;

        if (buflen == 0) {
                *data = (struct locking_tdb_data) { 0 };
                return true;
        }
        if (buflen < sizeof(uint32_t)) {
                return false;
        }

        share_mode_data_len = PULL_LE_U32(buf, 0);

        buf += sizeof(uint32_t);
        buflen -= sizeof(uint32_t);

        if (buflen < share_mode_data_len) {
                return false;
        }

        share_entries_len = buflen - share_mode_data_len;

        if ((share_entries_len % SHARE_MODE_ENTRY_SIZE) != 0) {
                return false;
        }

        *data = (struct locking_tdb_data) {
                .share_mode_data_buf = buf,
                .share_mode_data_len = share_mode_data_len,
                .share_entries = buf + share_mode_data_len,
                .num_share_entries = share_entries_len / SHARE_MODE_ENTRY_SIZE,
        };

        return true;
}

struct locking_tdb_data_fetch_state {
        TALLOC_CTX *mem_ctx;
        uint8_t *data;
        size_t datalen;
};

static void locking_tdb_data_fetch_fn(
        struct server_id exclusive,
        size_t num_shared,
        const struct server_id *shared,
        const uint8_t *data,
        size_t datalen,
        void *private_data)
{
        struct locking_tdb_data_fetch_state *state = private_data;
        state->datalen = datalen;
        state->data = talloc_memdup(state->mem_ctx, data, datalen);
}

static NTSTATUS locking_tdb_data_fetch(
        TDB_DATA key, TALLOC_CTX *mem_ctx, struct locking_tdb_data **ltdb)
{
        struct locking_tdb_data_fetch_state state = { 0 };
        struct locking_tdb_data *result = NULL;
        NTSTATUS status;
        bool ok;

        result = talloc_zero(mem_ctx, struct locking_tdb_data);
        if (result == NULL) {
                return NT_STATUS_NO_MEMORY;
        }
        state.mem_ctx = result;

        status = share_mode_g_lock_dump(key, locking_tdb_data_fetch_fn, &state);
        if (NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND)) {
                /*
                 * Just return an empty record
                 */
                goto done;
        }
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("share_mode_g_lock_dump failed: %s\n",
                        nt_errstr(status));
                return status;
        }
        if (state.datalen == 0) {
                goto done;
        }

        ok = locking_tdb_data_get(result, state.data, state.datalen);
        if (!ok) {
                DBG_ERR("locking_tdb_data_get failed for %zu bytes\n",
                          state.datalen);
                TALLOC_FREE(result);
                return NT_STATUS_INTERNAL_DB_CORRUPTION;
        }

done:
        *ltdb = result;
        return NT_STATUS_OK;
}

static NTSTATUS locking_tdb_data_store(
        TDB_DATA key,
        const struct locking_tdb_data *ltdb,
        const TDB_DATA *share_mode_dbufs,
        size_t num_share_mode_dbufs)
{
        uint8_t share_mode_data_len_buf[4];
        TDB_DATA dbufs[num_share_mode_dbufs+3];
        NTSTATUS status;

        if ((ltdb->share_mode_data_len == 0) &&
            (ltdb->num_share_entries == 0) &&
            (num_share_mode_dbufs == 0)) {
                /*
                 * Nothing to write
                 */
                status = share_mode_g_lock_writev(key, NULL, 0);
                if (!NT_STATUS_IS_OK(status)) {
                        DBG_ERR("share_mode_g_lock_writev(NULL) failed: %s\n",
                                nt_errstr(status));
                }
                return status;
        }

        PUSH_LE_U32(share_mode_data_len_buf, 0, ltdb->share_mode_data_len);

        dbufs[0] = (TDB_DATA) {
                .dptr = share_mode_data_len_buf,
                .dsize = sizeof(share_mode_data_len_buf),
        };
        dbufs[1] = (TDB_DATA) {
                .dptr = discard_const_p(uint8_t, ltdb->share_mode_data_buf),
                .dsize = ltdb->share_mode_data_len,
        };

        if (ltdb->num_share_entries > SIZE_MAX/SHARE_MODE_ENTRY_SIZE) {
                /* overflow */
                return NT_STATUS_BUFFER_OVERFLOW;
        }
        dbufs[2] = (TDB_DATA) {
                .dptr = discard_const_p(uint8_t, ltdb->share_entries),
                .dsize = ltdb->num_share_entries * SHARE_MODE_ENTRY_SIZE,
        };

        if (num_share_mode_dbufs != 0) {
                memcpy(&dbufs[3],
                       share_mode_dbufs,
                       num_share_mode_dbufs * sizeof(TDB_DATA));
        }

        status = share_mode_g_lock_writev(key, dbufs, ARRAY_SIZE(dbufs));
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("share_mode_g_lock_writev() failed: %s\n",
                        nt_errstr(status));
        }
        return status;
}

/*******************************************************************
 Get all share mode entries for a dev/inode pair.
********************************************************************/

static struct share_mode_data *parse_share_modes(
        TALLOC_CTX *mem_ctx,
        struct file_id id,
        const uint8_t *buf,
        size_t buflen)
{
        struct share_mode_data *d;
        enum ndr_err_code ndr_err;
        DATA_BLOB blob;

        /* See if we already have a cached copy of this key. */
        d = share_mode_memcache_fetch(mem_ctx, id, buf, buflen);
        if (d != NULL) {
                return d;
        }

        d = talloc(mem_ctx, struct share_mode_data);
        if (d == NULL) {
                DEBUG(0, ("talloc failed\n"));
                goto fail;
        }

        blob = (DATA_BLOB) {
                .data = discard_const_p(uint8_t, buf),
                .length = buflen,
        };
        ndr_err = ndr_pull_struct_blob_all(
                &blob, d, d, (ndr_pull_flags_fn_t)ndr_pull_share_mode_data);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                DBG_WARNING("ndr_pull_share_mode_data failed: %s\n",
                            ndr_errstr(ndr_err));
                goto fail;
        }

        if (DEBUGLEVEL >= 10) {
                DEBUG(10, ("parse_share_modes:\n"));
                NDR_PRINT_DEBUG(share_mode_data, d);
        }

        return d;
fail:
        TALLOC_FREE(d);
        return NULL;
}

static NTSTATUS share_mode_data_ltdb_store(struct share_mode_data *d,
                                           TDB_DATA key,
                                           struct locking_tdb_data *ltdb,
                                           const TDB_DATA *share_mode_dbufs,
                                           size_t num_share_mode_dbufs)
{
        DATA_BLOB blob = { 0 };
        NTSTATUS status;

        if (!d->modified) {
                DBG_DEBUG("share_mode_data not modified\n");
                goto store;
        }

        d->unique_content_epoch = generate_unique_u64(d->unique_content_epoch);

        if (DEBUGLEVEL >= 10) {
                DBG_DEBUG("\n");
                NDR_PRINT_DEBUG(share_mode_data, d);
        }

        if (ltdb->num_share_entries != 0 || num_share_mode_dbufs != 0) {
                enum ndr_err_code ndr_err;

                ndr_err = ndr_push_struct_blob(
                        &blob,
                        ltdb,
                        d,
                        (ndr_push_flags_fn_t)ndr_push_share_mode_data);
                if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                        DBG_ERR("ndr_push_share_mode_data failed: %s\n",
                                  ndr_errstr(ndr_err));
                        return ndr_map_error2ntstatus(ndr_err);
                }
        }

        ltdb->share_mode_data_buf = blob.data;
        ltdb->share_mode_data_len = blob.length;

store:
        status = locking_tdb_data_store(key,
                                        ltdb,
                                        share_mode_dbufs,
                                        num_share_mode_dbufs);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("locking_tdb_data_store failed: %s\n",
                        nt_errstr(status));
                return status;
        }

        d->modified = false;
        d->not_stored = (ltdb->share_mode_data_len == 0);

        return NT_STATUS_OK;
}

/*******************************************************************
 If modified, store the share_mode_data back into the database.
********************************************************************/

static NTSTATUS share_mode_data_store(struct share_mode_data *d)
{
        TDB_DATA key = locking_key(&d->id);
        struct locking_tdb_data *ltdb = NULL;
        NTSTATUS status;

        if (!d->modified) {
                DBG_DEBUG("not modified\n");
                return NT_STATUS_OK;
        }

        if (DEBUGLEVEL >= 10) {
                DBG_DEBUG("\n");
                NDR_PRINT_DEBUG(share_mode_data, d);
        }

        status = locking_tdb_data_fetch(key, d, &ltdb);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("locking_tdb_data_fetch failed: %s\n",
                        nt_errstr(status));
                return status;
        }

        status = share_mode_data_ltdb_store(d, key, ltdb, NULL, 0);
        TALLOC_FREE(ltdb);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("share_mode_data_ltdb_store failed: %s\n",
                        nt_errstr(status));
                return status;
        }

        return NT_STATUS_OK;
}

/*******************************************************************
 Allocate a new share_mode_data struct, mark it unmodified.
 fresh is set to note that currently there is no database entry.
********************************************************************/

static struct share_mode_data *fresh_share_mode_lock(
        TALLOC_CTX *mem_ctx, const char *servicepath,
        const struct smb_filename *smb_fname,
        const struct timespec *old_write_time)
{
        struct share_mode_data *d;

        if ((servicepath == NULL) || (smb_fname == NULL) ||
            (old_write_time == NULL)) {
                return NULL;
        }

        d = talloc_zero(mem_ctx, struct share_mode_data);
        if (d == NULL) {
                goto fail;
        }
        d->unique_content_epoch = generate_unique_u64(0);

        d->base_name = talloc_strdup(d, smb_fname->base_name);
        if (d->base_name == NULL) {
                goto fail;
        }
        if (smb_fname->stream_name != NULL) {
                d->stream_name = talloc_strdup(d, smb_fname->stream_name);
                if (d->stream_name == NULL) {
                        goto fail;
                }
        }
        d->servicepath = talloc_strdup(d, servicepath);
        if (d->servicepath == NULL) {
                goto fail;
        }
        d->old_write_time = full_timespec_to_nt_time(old_write_time);
        d->flags = SHARE_MODE_SHARE_DELETE |
                SHARE_MODE_SHARE_WRITE |
                SHARE_MODE_SHARE_READ;
        d->modified = false;
        d->not_stored = true;
        return d;
fail:
        DEBUG(0, ("talloc failed\n"));
        TALLOC_FREE(d);
        return NULL;
}

/*
 * Key that's locked with g_lock
 */
static struct file_id share_mode_lock_key_id = {};
static TDB_DATA share_mode_lock_key = {
        .dptr = (uint8_t *)&share_mode_lock_key_id,
        .dsize = sizeof(share_mode_lock_key_id),
};
static size_t share_mode_lock_key_refcount = 0;

static bool share_mode_g_lock_within_cb(TDB_DATA key)
{
        int cmp;

        if (current_share_mode_glck == NULL) {
                return false;
        }

        cmp = tdb_data_cmp(share_mode_lock_key, key);
        if (cmp != 0) {
                struct file_id_buf existing;

                DBG_ERR("Can not lock two share modes "
                        "simultaneously: existing %s requested %s\n",
                        file_id_str_buf(share_mode_lock_key_id, &existing),
                        hex_encode_talloc(talloc_tos(), key.dptr, key.dsize));
                smb_panic(__location__);
                return false;
        }

        return true;
}

/*
 * We can only ever have one share mode locked. Use a static
 * share_mode_data pointer that is shared by multiple nested
 * share_mode_lock structures, explicitly refcounted.
 */
static struct share_mode_data *static_share_mode_data = NULL;

/*******************************************************************
 Either fetch a share mode from the database, or allocate a fresh
 one if the record doesn't exist.
********************************************************************/

struct get_static_share_mode_data_state {
        TALLOC_CTX *mem_ctx;
        struct file_id id;
        const char *servicepath;
        const struct smb_filename *smb_fname;
        const struct timespec *old_write_time;
        NTSTATUS status;
};

static void get_static_share_mode_data_fn(
        struct server_id exclusive,
        size_t num_shared,
        const struct server_id *shared,
        const uint8_t *data,
        size_t datalen,
        void *private_data)
{
        struct get_static_share_mode_data_state *state = private_data;
        struct share_mode_data *d = NULL;
        struct locking_tdb_data ltdb = { 0 };

        if (datalen != 0) {
                bool ok;

                ok = locking_tdb_data_get(&ltdb, data, datalen);
                if (!ok) {
                        DBG_ERR("locking_tdb_data_get failed\n");
                        state->status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                        return;
                }
        }

        if (ltdb.share_mode_data_len == 0) {
                if (state->smb_fname == NULL) {
                        state->status = NT_STATUS_NOT_FOUND;
                        return;
                }
                d = fresh_share_mode_lock(
                        state->mem_ctx,
                        state->servicepath,
                        state->smb_fname,
                        state->old_write_time);
                if (d == NULL) {
                        state->status = NT_STATUS_NO_MEMORY;
                        return;
                }
        } else {
                d = parse_share_modes(
                        lock_ctx,
                        state->id,
                        ltdb.share_mode_data_buf,
                        ltdb.share_mode_data_len);
                if (d == NULL) {
                        state->status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                        return;
                }
        }

        d->id = state->id;
        static_share_mode_data = d;
}

static NTSTATUS get_static_share_mode_data(
        struct file_id id,
        const char *servicepath,
        const struct smb_filename *smb_fname,
        const struct timespec *old_write_time)
{
        struct get_static_share_mode_data_state state = {
                .mem_ctx = lock_ctx,
                .id = id,
                .servicepath = servicepath,
                .smb_fname = smb_fname,
                .old_write_time = old_write_time,
        };
        NTSTATUS status;

        SMB_ASSERT(static_share_mode_data == NULL);

        status = share_mode_g_lock_dump(
                share_mode_lock_key,
                get_static_share_mode_data_fn,
                &state);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_GET_SHARE_MODE_LOCK(status,
                        "share_mode_g_lock_dump failed: %s\n",
                        nt_errstr(status));
                return status;
        }
        if (!NT_STATUS_IS_OK(state.status)) {
                DBG_GET_SHARE_MODE_LOCK(status,
                        "get_static_share_mode_data_fn failed: %s\n",
                        nt_errstr(state.status));
                return state.status;
        }

        return NT_STATUS_OK;
}

struct file_id share_mode_lock_file_id(const struct share_mode_lock *lck)
{
        return lck->id;
}

NTSTATUS share_mode_lock_access_private_data(struct share_mode_lock *lck,
                                             struct share_mode_data **data)
{
        /*
         * For now we always have lck->cached_data,
         * but we may change that in future.
         */
        SMB_ASSERT(lck->cached_data != NULL);
        *data = lck->cached_data;
        return NT_STATUS_OK;
}

/*******************************************************************
 Get a share_mode_lock, Reference counted to allow nested calls.
********************************************************************/

static int share_mode_lock_destructor(struct share_mode_lock *lck);

static bool share_mode_lock_skip_g_lock;

static NTSTATUS get_share_mode_lock_internal(
        struct file_id id,
        const char *servicepath,
        const struct smb_filename *smb_fname,
        const struct timespec *old_write_time,
        struct share_mode_lock *lck)
{
        NTSTATUS status;

        *lck = (struct share_mode_lock) {
                .id = id,
        };

        if (share_mode_lock_key_refcount == 0) {
                if (!share_mode_lock_skip_g_lock) {
                        TDB_DATA key = locking_key(&id);

                        status = g_lock_lock(
                                lock_ctx,
                                key,
                                G_LOCK_WRITE,
                                (struct timeval) { .tv_sec = 3600 },
                                NULL, NULL);
                        if (!NT_STATUS_IS_OK(status)) {
                                DBG_DEBUG("g_lock_lock failed: %s\n",
                                          nt_errstr(status));
                                return status;
                        }
                }
                share_mode_lock_key_id = id;
        }

        if (!file_id_equal(&share_mode_lock_key_id, &id)) {
                struct file_id_buf existing;
                struct file_id_buf requested;

                DBG_ERR("Can not lock two share modes "
                        "simultaneously: existing %s requested %s\n",
                        file_id_str_buf(share_mode_lock_key_id, &existing),
                        file_id_str_buf(id, &requested));
                smb_panic(__location__);
                goto fail;
        }

        SMB_ASSERT(share_mode_lock_key_refcount < SIZE_MAX);
        share_mode_lock_key_refcount += 1;

        if (static_share_mode_data != NULL) {
                goto done;
        }

        status = get_static_share_mode_data(
                id,
                servicepath,
                smb_fname,
                old_write_time);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_DEBUG("get_static_share_mode_data failed: %s\n",
                          nt_errstr(status));
                share_mode_lock_key_refcount -= 1;
                goto fail;
        }
done:
        lck->cached_data = static_share_mode_data;

        if (CHECK_DEBUGLVL(DBGLVL_DEBUG)) {
                struct file_id_buf returned;

                DBG_DEBUG("Returning %s (data_cached=%u key_refcount=%zu)\n",
                          file_id_str_buf(id, &returned),
                          static_share_mode_data != NULL,
                          share_mode_lock_key_refcount);
        }

        return NT_STATUS_OK;
fail:
        if (share_mode_lock_key_refcount == 0) {
                if (!share_mode_lock_skip_g_lock) {
                        NTSTATUS ulstatus = g_lock_unlock(lock_ctx, share_mode_lock_key);
                        if (!NT_STATUS_IS_OK(ulstatus)) {
                                DBG_ERR("g_lock_unlock failed: %s\n",
                                        nt_errstr(ulstatus));
                        }
                }
        }
        return status;
}

static NTSTATUS put_share_mode_lock_internal(struct share_mode_lock *lck)
{
        NTSTATUS status;

        SMB_ASSERT(share_mode_lock_key_refcount > 0);
        share_mode_lock_key_refcount -= 1;

        if (share_mode_lock_key_refcount > 0) {
                return NT_STATUS_OK;
        }

        status = share_mode_data_store(static_share_mode_data);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("share_mode_data_store failed: %s\n",
                        nt_errstr(status));
                return status;
        }

        if (!share_mode_lock_skip_g_lock) {
                status = g_lock_unlock(lock_ctx, share_mode_lock_key);
                if (!NT_STATUS_IS_OK(status)) {
                        DBG_ERR("g_lock_unlock failed: %s\n",
                                nt_errstr(status));
                        return status;
                }
        }

        if (!static_share_mode_data->not_stored) {
                /*
                 * This is worth keeping. Without share modes,
                 * share_mode_data_store above has left nothing in the
                 * database.
                 */
                share_mode_memcache_store(static_share_mode_data);
                static_share_mode_data = NULL;
        }

        TALLOC_FREE(static_share_mode_data);
        return NT_STATUS_OK;
}

static int share_mode_lock_destructor(struct share_mode_lock *lck)
{
        NTSTATUS status;

        status = put_share_mode_lock_internal(lck);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("put_share_mode_lock_internal failed: %s\n",
                        nt_errstr(status));
                smb_panic("put_share_mode_lock_internal failed\n");
        }

        return 0;
}

/*******************************************************************
 Fetch a share mode where we know one MUST exist. This call reference
 counts it internally to allow for nested lock fetches.
********************************************************************/

struct share_mode_lock *get_existing_share_mode_lock(TALLOC_CTX *mem_ctx,
                                                     const struct file_id id)
{
        struct share_mode_lock *lck = NULL;
        NTSTATUS status;

        lck = talloc(mem_ctx, struct share_mode_lock);
        if (lck == NULL) {
                return NULL;
        }

        status = get_share_mode_lock_internal(id,
                                              NULL, /* servicepath */
                                              NULL, /* smb_fname */
                                              NULL, /* old_write_time */
                                              lck);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_GET_SHARE_MODE_LOCK(status,
                        "get_share_mode_lock_internal() failed - %s\n",
                        nt_errstr(status));
                TALLOC_FREE(lck);
                return NULL;
        }

        talloc_set_destructor(lck, share_mode_lock_destructor);
        return lck;
}

static void share_mode_wakeup_waiters_fn(
        struct share_mode_lock *lck,
        void *private_data)
{
        if (share_mode_g_lock_within_cb(share_mode_lock_key)) {
                g_lock_lock_cb_wake_watchers(current_share_mode_glck);
                return;
        }

        g_lock_wake_watchers(lock_ctx, share_mode_lock_key);
}

NTSTATUS share_mode_wakeup_waiters(struct file_id id)
{
        return share_mode_do_locked_vfs_denied(id,
                                               share_mode_wakeup_waiters_fn,
                                               NULL);
}

struct fsp_update_share_mode_flags_state {
        struct files_struct *fsp;
        enum ndr_err_code ndr_err;
        uint64_t share_mode_epoch;
        uint16_t share_mode_flags;
};

static void fsp_update_share_mode_flags_fn(
        struct server_id exclusive,
        size_t num_shared,
        const struct server_id *shared,
        const uint8_t *data,
        size_t datalen,
        void *private_data)
{
        struct fsp_update_share_mode_flags_state *state = private_data;
        struct locking_tdb_data ltdb = { 0 };

        if (datalen != 0) {
                bool ok = locking_tdb_data_get(&ltdb, data, datalen);
                if (!ok) {
                        DBG_DEBUG("locking_tdb_data_get failed\n");
                        return;
                }
        }

        if (ltdb.share_mode_data_len == 0) {
                /* Likely a ctdb tombstone record, ignore it */
                return;
        }

        if (exclusive.pid != 0) {
                struct server_id self =
                        messaging_server_id(state->fsp->conn->sconn->msg_ctx);
                bool is_self = server_id_equal(&self, &exclusive);

                if (!is_self) {
                        /*
                         * If someone else is holding an exclusive
                         * lock, pretend there's a read lease
                         */
                        state->share_mode_flags = SHARE_MODE_LEASE_READ;
                        return;
                }
        }

        state->ndr_err = get_share_mode_blob_header(ltdb.share_mode_data_buf,
                                                    ltdb.share_mode_data_len,
                                                    &state->share_mode_epoch,
                                                    &state->share_mode_flags);
}

static NTSTATUS fsp_update_share_mode_flags(struct files_struct *fsp)
{
        struct fsp_update_share_mode_flags_state state = { .fsp = fsp, };
        int seqnum = g_lock_seqnum(lock_ctx);
        TDB_DATA key = {0};
        NTSTATUS status;

        if (seqnum == fsp->share_mode_flags_seqnum) {
                return NT_STATUS_OK;
        }

        key = locking_key(&fsp->file_id);
        status = share_mode_g_lock_dump(key,
                             fsp_update_share_mode_flags_fn,
                             &state);
        if (!NT_STATUS_IS_OK(status)) {
                /* no DBG_GET_SHARE_MODE_LOCK here! */
                DBG_ERR("share_mode_g_lock_dump returned %s\n",
                        nt_errstr(status));
                return status;
        }

        if (!NDR_ERR_CODE_IS_SUCCESS(state.ndr_err)) {
                DBG_ERR("get_share_mode_blob_header returned %s\n",
                        ndr_errstr(state.ndr_err));
                return ndr_map_error2ntstatus(state.ndr_err);
        }

        fsp->share_mode_flags_seqnum = seqnum;
        fsp->share_mode_flags = state.share_mode_flags;

        return NT_STATUS_OK;
}

bool file_has_read_lease(struct files_struct *fsp)
{
        NTSTATUS status;

        status = fsp_update_share_mode_flags(fsp);
        if (!NT_STATUS_IS_OK(status)) {
                /* Safe default for leases */
                return true;
        }

        return (fsp->share_mode_flags & SHARE_MODE_LEASE_READ) != 0;
}

#define share_mode_lock_assert_private_data(__lck) \
        _share_mode_lock_assert_private_data(__lck, __func__, __location__)
static struct share_mode_data *_share_mode_lock_assert_private_data(
                                        struct share_mode_lock *lck,
                                        const char *caller_function,
                                        const char *caller_location)
{
        struct share_mode_data *d = NULL;
        NTSTATUS status;

        status = share_mode_lock_access_private_data(lck, &d);
        if (!NT_STATUS_IS_OK(status)) {
                struct file_id id = share_mode_lock_file_id(lck);
                struct file_id_buf id_buf;
                /* Any error recovery possible here ? */
                D_ERR("%s:%s(): share_mode_lock_access_private_data() "
                      "failed for id=%s - %s\n",
                      caller_location, caller_function,
                      file_id_str_buf(id, &id_buf),
                      nt_errstr(status));
                smb_panic(caller_location);
                return NULL;
        }

        return d;
}

NTTIME share_mode_changed_write_time(struct share_mode_lock *lck)
{
        struct share_mode_data *d = share_mode_lock_assert_private_data(lck);
        return d->changed_write_time;
}

void share_mode_set_changed_write_time(struct share_mode_lock *lck, struct timespec write_time)
{
        struct file_id fileid = share_mode_lock_file_id(lck);
        struct share_mode_data *d = share_mode_lock_assert_private_data(lck);
        struct file_id_buf ftmp;
        struct timeval_buf tbuf;
        NTTIME nt = full_timespec_to_nt_time(&write_time);

        DBG_INFO("%s id=%s\n",
                 timespec_string_buf(&write_time, true, &tbuf),
                 file_id_str_buf(fileid, &ftmp));

        if (d->changed_write_time != nt) {
                d->modified = true;
                d->changed_write_time = nt;
        }
}

void share_mode_set_old_write_time(struct share_mode_lock *lck, struct timespec write_time)
{
        struct file_id fileid = share_mode_lock_file_id(lck);
        struct share_mode_data *d = share_mode_lock_assert_private_data(lck);
        struct file_id_buf ftmp;
        struct timeval_buf tbuf;
        NTTIME nt = full_timespec_to_nt_time(&write_time);

        DBG_INFO("%s id=%s\n",
                 timespec_string_buf(&write_time, true, &tbuf),
                 file_id_str_buf(fileid, &ftmp));

        if (d->changed_write_time != nt) {
                d->modified = true;
                d->old_write_time = nt;
        }
}

const char *share_mode_servicepath(struct share_mode_lock *lck)
{
        struct share_mode_data *d = share_mode_lock_assert_private_data(lck);
        return d->servicepath;
}

char *share_mode_filename(TALLOC_CTX *mem_ctx, struct share_mode_lock *lck)
{
        struct share_mode_data *d = share_mode_lock_assert_private_data(lck);
        bool has_stream = (d->stream_name != NULL);
        char *fname = NULL;

        fname = talloc_asprintf(
                mem_ctx,
                "%s%s%s",
                d->base_name,
                has_stream ? ":" : "",
                has_stream ? d->stream_name : "");
        return fname;
}

char *share_mode_data_dump(
        TALLOC_CTX *mem_ctx, struct share_mode_lock *lck)
{
        struct share_mode_data *d = share_mode_lock_assert_private_data(lck);
        struct ndr_print *p = talloc(mem_ctx, struct ndr_print);
        char *ret = NULL;

        if (p == NULL) {
                return NULL;
        }

        *p = (struct ndr_print) {
                .print = ndr_print_string_helper,
                .depth = 1,
                .private_data = talloc_strdup(mem_ctx, ""),
        };

        if (p->private_data == NULL) {
                TALLOC_FREE(p);
                return NULL;
        }

        ndr_print_share_mode_data(p, "SHARE_MODE_DATA", d);

        ret = p->private_data;

        TALLOC_FREE(p);

        return ret;
}

void share_mode_flags_get(
        struct share_mode_lock *lck,
        uint32_t *access_mask,
        uint32_t *share_mode,
        uint32_t *lease_type)
{
        struct share_mode_data *d = share_mode_lock_assert_private_data(lck);
        uint16_t flags = d->flags;

        if (access_mask != NULL) {
                *access_mask =
                        ((flags & SHARE_MODE_ACCESS_READ) ?
                         FILE_READ_DATA : 0) |
                        ((flags & SHARE_MODE_ACCESS_WRITE) ?
                         FILE_WRITE_DATA : 0) |
                        ((flags & SHARE_MODE_ACCESS_DELETE) ?
                         DELETE_ACCESS : 0);
        }
        if (share_mode != NULL) {
                *share_mode =
                        ((flags & SHARE_MODE_SHARE_READ) ?
                         FILE_SHARE_READ : 0) |
                        ((flags & SHARE_MODE_SHARE_WRITE) ?
                         FILE_SHARE_WRITE : 0) |
                        ((flags & SHARE_MODE_SHARE_DELETE) ?
                         FILE_SHARE_DELETE : 0);
        }
        if (lease_type != NULL) {
                *lease_type =
                        ((flags & SHARE_MODE_LEASE_READ) ?
                         SMB2_LEASE_READ : 0) |
                        ((flags & SHARE_MODE_LEASE_WRITE) ?
                         SMB2_LEASE_WRITE : 0) |
                        ((flags & SHARE_MODE_LEASE_HANDLE) ?
                         SMB2_LEASE_HANDLE : 0);
        }
}

void share_mode_flags_set(
        struct share_mode_lock *lck,
        uint32_t access_mask,
        uint32_t share_mode,
        uint32_t lease_type,
        bool *modified)
{
        struct share_mode_data *d = share_mode_lock_assert_private_data(lck);
        uint16_t flags = 0;

        flags |= (access_mask & (FILE_READ_DATA | FILE_EXECUTE)) ?
                SHARE_MODE_ACCESS_READ : 0;
        flags |= (access_mask & (FILE_WRITE_DATA | FILE_APPEND_DATA)) ?
                SHARE_MODE_ACCESS_WRITE : 0;
        flags |= (access_mask & (DELETE_ACCESS)) ?
                SHARE_MODE_ACCESS_DELETE : 0;

        flags |= (share_mode & FILE_SHARE_READ) ?
                SHARE_MODE_SHARE_READ : 0;
        flags |= (share_mode & FILE_SHARE_WRITE) ?
                SHARE_MODE_SHARE_WRITE : 0;
        flags |= (share_mode & FILE_SHARE_DELETE) ?
                SHARE_MODE_SHARE_DELETE : 0;

        flags |= (lease_type & SMB2_LEASE_READ) ?
                SHARE_MODE_LEASE_READ : 0;
        flags |= (lease_type & SMB2_LEASE_WRITE) ?
                SHARE_MODE_LEASE_WRITE : 0;
        flags |= (lease_type & SMB2_LEASE_HANDLE) ?
                SHARE_MODE_LEASE_HANDLE : 0;

        if (d->flags == flags) {
                return;
        }

        if (modified != NULL) {
                *modified = true;
        }
        d->flags = flags;
        d->modified = true;
}

struct share_mode_watch_state {
        bool blockerdead;
        struct server_id blocker;
        bool within_cb;
};

static void share_mode_watch_done(struct tevent_req *subreq);

struct tevent_req *share_mode_watch_send(
        TALLOC_CTX *mem_ctx,
        struct tevent_context *ev,
        struct share_mode_lock *lck,
        struct server_id blocker)
{
        struct file_id id = share_mode_lock_file_id(lck);
        TDB_DATA key = locking_key(&id);
        struct tevent_req *req = NULL, *subreq = NULL;
        struct share_mode_watch_state *state = NULL;

        req = tevent_req_create(
                mem_ctx, &state, struct share_mode_watch_state);
        if (req == NULL) {
                return NULL;
        }

        if (share_mode_g_lock_within_cb(key)) {
                state->within_cb = true;
                subreq = g_lock_lock_cb_watch_data_send(state, ev,
                                                        current_share_mode_glck,
                                                        blocker);
                if (tevent_req_nomem(subreq, req)) {
                        return tevent_req_post(req, ev);
                }
        } else {
                subreq = g_lock_watch_data_send(state, ev, lock_ctx, key, blocker);
                if (tevent_req_nomem(subreq, req)) {
                        return tevent_req_post(req, ev);
                }
        }
        tevent_req_set_callback(subreq, share_mode_watch_done, req);
        return req;
}

static void share_mode_watch_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct share_mode_watch_state *state = tevent_req_data(
                req, struct share_mode_watch_state);
        NTSTATUS status;

        if (state->within_cb) {
                status = g_lock_lock_cb_watch_data_recv(
                        subreq, &state->blockerdead, &state->blocker);
                if (tevent_req_nterror(req, status)) {
                        return;
                }
        } else {
                status = g_lock_watch_data_recv(
                        subreq, &state->blockerdead, &state->blocker);
                if (tevent_req_nterror(req, status)) {
                        return;
                }
        }

        tevent_req_done(req);
}

NTSTATUS share_mode_watch_recv(
        struct tevent_req *req, bool *blockerdead, struct server_id *blocker)
{
        struct share_mode_watch_state *state = tevent_req_data(
                req, struct share_mode_watch_state);
        NTSTATUS status;

        if (tevent_req_is_nterror(req, &status)) {
                return status;
        }
        if (blockerdead != NULL) {
                *blockerdead = state->blockerdead;
        }
        if (blocker != NULL) {
                *blocker = state->blocker;
        }
        return NT_STATUS_OK;
}

struct fetch_share_mode_unlocked_state {
        TALLOC_CTX *mem_ctx;
        struct file_id id;
        struct share_mode_lock *lck;
};

static void fetch_share_mode_unlocked_parser(
        struct server_id exclusive,
        size_t num_shared,
        const struct server_id *shared,
        const uint8_t *data,
        size_t datalen,
        void *private_data)
{
        struct fetch_share_mode_unlocked_state *state = private_data;
        struct locking_tdb_data ltdb = { 0 };

        if (datalen != 0) {
                bool ok = locking_tdb_data_get(&ltdb, data, datalen);
                if (!ok) {
                        DBG_DEBUG("locking_tdb_data_get failed\n");
                        return;
                }
        }

        if (ltdb.share_mode_data_len == 0) {
                /* Likely a ctdb tombstone record, ignore it */
                return;
        }

        state->lck = talloc(state->mem_ctx, struct share_mode_lock);
        if (state->lck == NULL) {
                DEBUG(0, ("talloc failed\n"));
                return;
        }
        state->lck->id = state->id;

        state->lck->cached_data = parse_share_modes(
                state->lck,
                state->id,
                ltdb.share_mode_data_buf,
                ltdb.share_mode_data_len);
        if (state->lck->cached_data == NULL) {
                DBG_DEBUG("parse_share_modes failed\n");
                TALLOC_FREE(state->lck);
        }
}

/*******************************************************************
 Get a share_mode_lock without locking the database or reference
 counting. Used by smbstatus to display existing share modes.
********************************************************************/

struct share_mode_lock *fetch_share_mode_unlocked(TALLOC_CTX *mem_ctx,
                                                  struct file_id id)
{
        struct fetch_share_mode_unlocked_state state = {
                .mem_ctx = mem_ctx,
                .id = id,
        };
        TDB_DATA key = locking_key(&id);
        NTSTATUS status;

        status = g_lock_dump(
                lock_ctx, key, fetch_share_mode_unlocked_parser, &state);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_DEBUG("g_lock_dump failed: %s\n", nt_errstr(status));
                return NULL;
        }
        return state.lck;
}

struct fetch_share_mode_state {
        struct file_id id;
        struct share_mode_lock *lck;
        NTSTATUS status;
};

static void fetch_share_mode_fn(
        struct server_id exclusive,
        size_t num_shared,
        const struct server_id *shared,
        const uint8_t *data,
        size_t datalen,
        void *private_data);
static void fetch_share_mode_done(struct tevent_req *subreq);

/**
 * @brief Get a share_mode_lock without locking or refcounting
 *
 * This can be used in a clustered Samba environment where the async dbwrap
 * request is sent over a socket to the local ctdbd. If the send queue is full
 * and the caller was issuing multiple async dbwrap requests in a loop, the
 * caller knows it's probably time to stop sending requests for now and try
 * again later.
 *
 * @param[in]  mem_ctx The talloc memory context to use.
 *
 * @param[in]  ev      The event context to work on.
 *
 * @param[in]  id      The file id for the locking.tdb key
 *
 * @param[out] queued  This boolean out parameter tells the caller whether the
 *                     async request is blocked in a full send queue:
 *
 *                     false := request is dispatched
 *
 *                     true  := send queue is full, request waiting to be
 *                              dispatched
 *
 * @return             The new async request, NULL on error.
 **/
struct tevent_req *fetch_share_mode_send(TALLOC_CTX *mem_ctx,
                                         struct tevent_context *ev,
                                         struct file_id id,
                                         bool *queued)
{
        struct tevent_req *req = NULL, *subreq = NULL;
        struct fetch_share_mode_state *state = NULL;

        *queued = false;

        req = tevent_req_create(mem_ctx, &state,
                                struct fetch_share_mode_state);
        if (req == NULL) {
                return NULL;
        }
        state->id = id;

        subreq = g_lock_dump_send(
                state,
                ev,
                lock_ctx,
                locking_key(&id),
                fetch_share_mode_fn,
                state);
        if (tevent_req_nomem(subreq, req)) {
                return tevent_req_post(req, ev);
        }
        tevent_req_set_callback(subreq, fetch_share_mode_done, req);
        return req;
}

static void fetch_share_mode_fn(
        struct server_id exclusive,
        size_t num_shared,
        const struct server_id *shared,
        const uint8_t *data,
        size_t datalen,
        void *private_data)
{
        struct fetch_share_mode_state *state = talloc_get_type_abort(
                private_data, struct fetch_share_mode_state);
        struct locking_tdb_data ltdb = { 0 };

        if (datalen != 0) {
                bool ok = locking_tdb_data_get(&ltdb, data, datalen);
                if (!ok) {
                        DBG_DEBUG("locking_tdb_data_get failed\n");
                        return;
                }
        }

        if (ltdb.share_mode_data_len == 0) {
                /* Likely a ctdb tombstone record, ignore it */
                return;
        }

        state->lck = talloc(state, struct share_mode_lock);
        if (state->lck == NULL) {
                DBG_WARNING("talloc failed\n");
                state->status = NT_STATUS_NO_MEMORY;
                return;
        }
        state->lck->id = state->id,

        state->lck->cached_data = parse_share_modes(
                state->lck,
                state->id,
                ltdb.share_mode_data_buf,
                ltdb.share_mode_data_len);
        if (state->lck->cached_data == NULL) {
                DBG_DEBUG("parse_share_modes failed\n");
                state->status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                TALLOC_FREE(state->lck);
                return;
        }
}

static void fetch_share_mode_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct fetch_share_mode_state *state = tevent_req_data(
                req, struct fetch_share_mode_state);
        NTSTATUS status;

        status = g_lock_dump_recv(subreq);
        TALLOC_FREE(subreq);
        if (tevent_req_nterror(req, status)) {
                return;
        }
        if (tevent_req_nterror(req, state->status)) {
                return;
        }
        tevent_req_done(req);
}

NTSTATUS fetch_share_mode_recv(struct tevent_req *req,
                               TALLOC_CTX *mem_ctx,
                               struct share_mode_lock **_lck)
{
        struct fetch_share_mode_state *state = tevent_req_data(
                req, struct fetch_share_mode_state);
        struct share_mode_lock *lck = NULL;

        NTSTATUS status;

        if (tevent_req_is_nterror(req, &status)) {
                tevent_req_received(req);
                return status;
        }

        if (state->lck == NULL) {
                tevent_req_received(req);
                return NT_STATUS_NOT_FOUND;
        }

        lck = talloc_move(mem_ctx, &state->lck);

        if (DEBUGLEVEL >= 10) {
                DBG_DEBUG("share_mode_data:\n");
                NDR_PRINT_DEBUG(share_mode_data, lck->cached_data);
        }

        *_lck = lck;
        tevent_req_received(req);
        return NT_STATUS_OK;
}

struct share_mode_forall_state {
        TDB_DATA key;
        int (*fn)(struct file_id fid,
                  const struct share_mode_data *data,
                  void *private_data);
        void *private_data;
};

static void share_mode_forall_dump_fn(
        struct server_id exclusive,
        size_t num_shared,
        const struct server_id *shared,
        const uint8_t *data,
        size_t datalen,
        void *private_data)
{
        struct share_mode_forall_state *state = private_data;
        struct file_id fid;
        struct locking_tdb_data ltdb = { 0 };
        bool ok;
        struct share_mode_data *d;

        if (state->key.dsize != sizeof(fid)) {
                DBG_DEBUG("Got invalid key length %zu\n", state->key.dsize);
                return;
        }
        memcpy(&fid, state->key.dptr, sizeof(fid));

        ok = locking_tdb_data_get(&ltdb, data, datalen);
        if (!ok) {
                DBG_DEBUG("locking_tdb_data_get() failed\n");
                return;
        }

        d = parse_share_modes(
                talloc_tos(),
                fid,
                ltdb.share_mode_data_buf,
                ltdb.share_mode_data_len);
        if (d == NULL) {
                DBG_DEBUG("parse_share_modes() failed\n");
                return;
        }

        state->fn(fid, d, state->private_data);
        TALLOC_FREE(d);
}

static int share_mode_forall_fn(TDB_DATA key, void *private_data)
{
        struct share_mode_forall_state *state = private_data;
        NTSTATUS status;

        state->key = key;

        status = share_mode_g_lock_dump(
                key, share_mode_forall_dump_fn, private_data);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_GET_SHARE_MODE_LOCK(status,
                        "g_lock_dump failed: %s\n",
                        nt_errstr(status));
        }
        return 0;
}

int share_mode_forall(int (*fn)(struct file_id fid,
                                const struct share_mode_data *data,
                                void *private_data),
                      void *private_data)
{
        struct share_mode_forall_state state = {
                .fn = fn,
                .private_data = private_data
        };
        int ret;

        if (lock_ctx == NULL) {
                return 0;
        }

        ret = g_lock_locks(
                lock_ctx, share_mode_forall_fn, &state);
        if (ret < 0) {
                DBG_ERR("g_lock_locks failed\n");
        }
        return ret;
}

struct share_entry_forall_state {
        struct file_id fid;
        const struct share_mode_data *data;
        int (*fn)(struct file_id fid,
                  const struct share_mode_data *data,
                  const struct share_mode_entry *entry,
                  void *private_data);
        void *private_data;
        int ret;
};

static bool share_entry_traverse_walker(
        struct share_mode_entry *e,
        bool *modified,
        void *private_data)
{
        struct share_entry_forall_state *state = private_data;

        state->ret = state->fn(
                state->fid, state->data, e, state->private_data);
        return (state->ret != 0);
}

static int share_entry_traverse_fn(struct file_id fid,
                                   const struct share_mode_data *data,
                                   void *private_data)
{
        struct share_entry_forall_state *state = private_data;
        struct share_mode_lock lck = {
                .id = fid,
                .cached_data = discard_const_p(struct share_mode_data, data)
        };
        bool ok;

        state->fid = fid;
        state->data = data;

        ok = share_mode_forall_entries(
                &lck, share_entry_traverse_walker, state);
        if (!ok) {
                DBG_ERR("share_mode_forall_entries failed\n");
                return false;
        }

        return state->ret;
}

/*******************************************************************
 Call the specified function on each entry under management by the
 share mode system.
********************************************************************/

int share_entry_forall(int (*fn)(struct file_id fid,
                                 const struct share_mode_data *data,
                                 const struct share_mode_entry *entry,
                                 void *private_data),
                      void *private_data)
{
        struct share_entry_forall_state state = {
                .fn = fn, .private_data = private_data };

        return share_mode_forall(share_entry_traverse_fn, &state);
}

static int share_mode_entry_cmp(
        struct server_id pid1,
        uint64_t share_file_id1,
        struct server_id pid2,
        uint64_t share_file_id2)
{
        int cmp;

        cmp = server_id_cmp(&pid1, &pid2);
        if (cmp != 0) {
                return cmp;
        }
        if (share_file_id1 != share_file_id2) {
                return (share_file_id1 < share_file_id2) ? -1 : 1;
        }
        return 0;
}

static size_t share_mode_entry_find(
        const uint8_t *data,
        size_t num_share_modes,
        struct server_id pid,
        uint64_t share_file_id,
        struct share_mode_entry *e,
        bool *match)
{
        ssize_t left, right, middle;

        *match = false;

        if (num_share_modes == 0) {
                return 0;
        }

        left = 0;
        right = (num_share_modes-1);

        while (left <= right) {
                const uint8_t *middle_ptr = NULL;
                int cmp;
                bool ok;

                middle = left + ((right - left) / 2);
                middle_ptr = data + middle * SHARE_MODE_ENTRY_SIZE;

                DBG_DEBUG("left=%zu, right=%zu, middle=%zu, middle_ptr=%p\n",
                          left,
                          right,
                          middle,
                          middle_ptr);

                ok = share_mode_entry_get(middle_ptr, e);
                if (!ok) {
                        DBG_DEBUG("share_mode_entry_get failed\n");
                        return 0;
                }

                cmp = share_mode_entry_cmp(
                        e->pid, e->share_file_id, pid, share_file_id);
                if (cmp == 0) {
                        *match = true;
                        return middle;
                }

                if (cmp < 0) {
                        right = middle-1;
                } else {
                        left = middle+1;
                }
        }

        return left;
}

bool set_share_mode(struct share_mode_lock *lck,
                    struct files_struct *fsp,
                    uid_t uid,
                    uint64_t mid,
                    uint16_t op_type,
                    const struct smb2_lease_key *lease_key,
                    uint32_t share_access,
                    uint32_t access_mask)
{
        struct share_mode_data *d = share_mode_lock_assert_private_data(lck);
        TDB_DATA key = locking_key(&d->id);
        struct server_id my_pid = messaging_server_id(
                fsp->conn->sconn->msg_ctx);
        struct locking_tdb_data *ltdb = NULL;
        size_t idx;
        struct share_mode_entry e = { .pid.pid = 0 };
        struct share_mode_entry_buf e_buf;
        NTSTATUS status;
        bool ok, found;

        TDB_DATA dbufs[3];
        size_t num_dbufs = 0;

        status = locking_tdb_data_fetch(key, talloc_tos(), &ltdb);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("locking_tdb_data_fetch failed: %s\n",
                        nt_errstr(status));
                return false;
        }
        DBG_DEBUG("num_share_modes=%zu\n", ltdb->num_share_entries);

        idx = share_mode_entry_find(
                ltdb->share_entries,
                ltdb->num_share_entries,
                my_pid,
                fh_get_gen_id(fsp->fh),
                &e,
                &found);
        if (found) {
                DBG_WARNING("Found duplicate share mode\n");
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto done;
        }

        e = (struct share_mode_entry) {
                .pid = my_pid,
                .share_access = share_access,
                .private_options = fh_get_private_options(fsp->fh),
                .access_mask = access_mask,
                .op_mid = mid,
                .op_type = op_type,
                .time.tv_sec = fsp->open_time.tv_sec,
                .time.tv_usec = fsp->open_time.tv_usec,
                .share_file_id = fh_get_gen_id(fsp->fh),
                .uid = (uint32_t)uid,
                .flags = (fsp->posix_flags & FSP_POSIX_FLAGS_OPEN) ?
                        SHARE_MODE_FLAG_POSIX_OPEN : 0,
                .name_hash = fsp->name_hash,
        };

        if (op_type == LEASE_OPLOCK) {
                const struct GUID *client_guid = fsp_client_guid(fsp);
                e.client_guid = *client_guid;
                e.lease_key = *lease_key;
        }

        ok = share_mode_entry_put(&e, &e_buf);
        if (!ok) {
                DBG_DEBUG("share_mode_entry_put failed\n");
                status = NT_STATUS_INTERNAL_ERROR;
                goto done;
        }

        DBG_DEBUG("idx=%zu, found=%d\n", idx, (int)found);

        if (idx > 0) {
                dbufs[num_dbufs] = (TDB_DATA) {
                        .dptr = discard_const_p(uint8_t, ltdb->share_entries),
                        .dsize = idx * SHARE_MODE_ENTRY_SIZE,
                };
                num_dbufs += 1;
        }

        dbufs[num_dbufs] = (TDB_DATA) {
                .dptr = e_buf.buf, .dsize = SHARE_MODE_ENTRY_SIZE,
        };
        num_dbufs += 1;

        if (idx < ltdb->num_share_entries) {
                size_t num_after_idx = (ltdb->num_share_entries-idx);
                dbufs[num_dbufs] = (TDB_DATA) {
                        .dptr = discard_const_p(uint8_t, ltdb->share_entries) +
                                idx * SHARE_MODE_ENTRY_SIZE,
                        .dsize = num_after_idx * SHARE_MODE_ENTRY_SIZE,
                };
                num_dbufs += 1;
        }

        {
                size_t i;
                for (i=0; i<num_dbufs; i++) {
                        DBG_DEBUG("dbufs[%zu]=(%p, %zu)\n",
                                  i,
                                  dbufs[i].dptr,
                                  dbufs[i].dsize);
                }
        }

        if (num_dbufs == 1) {
                /*
                 * Storing a fresh record with just one share entry
                 */
                d->modified = true;
        }

        /*
         * If there was any existing data in
         * ltdb->share_entries, it's now been
         * moved and we've split it into:
         *
         * num_dbufs = 3
         * dbufs[0] -> old sorted data less than new_entry
         * dbufs[1] -> new_share_mode_entry
         * dbufs[2] -> old sorted_data greater than new entry.
         *
         * So the old data inside ltdb->share_entries is
         * no longer valid.
         *
         * If we're storing a brand new entry the
         * dbufs look like:
         *
         * num_dbufs = 1
         * dbufs[0] -> new_share_mode_entry
         *
         * Either way we must set ltdb->share_entries = NULL
         * and ltdb->num_share_entries = 0 so that
         * locking_tdb_data_store() doesn't use it to
         * store any data. It's no longer there.
         */

        ltdb->share_entries = NULL;
        ltdb->num_share_entries = 0;

        status = share_mode_data_ltdb_store(d, key, ltdb, dbufs, num_dbufs);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("share_mode_data_ltdb_store failed: %s\n",
                        nt_errstr(status));
        }
done:
        TALLOC_FREE(ltdb);
        return NT_STATUS_IS_OK(status);
}

static bool share_mode_for_one_entry(
        bool (*fn)(struct share_mode_entry *e,
                   bool *modified,
                   void *private_data),
        void *private_data,
        size_t *i,
        uint8_t *data,
        size_t *num_share_modes,
        bool *writeback)
{
        DATA_BLOB blob = {
                .data = data + (*i) * SHARE_MODE_ENTRY_SIZE,
                .length = SHARE_MODE_ENTRY_SIZE,
        };
        struct share_mode_entry e = {.pid.pid=0};
        enum ndr_err_code ndr_err = NDR_ERR_SUCCESS;
        bool modified = false;
        bool stop = false;
        struct server_id e_pid;
        uint64_t e_share_file_id;

        ndr_err = ndr_pull_struct_blob_all_noalloc(
                &blob,
                &e,
                (ndr_pull_flags_fn_t)ndr_pull_share_mode_entry);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                DBG_WARNING("ndr_pull_share_mode_entry failed\n");
                *i += 1;
                return false;
        }
        if (DEBUGLEVEL >= 10) {
                DBG_DEBUG("entry[%zu]:\n", *i);
                NDR_PRINT_DEBUG(share_mode_entry, &e);
        }

        e_pid = e.pid;
        e_share_file_id = e.share_file_id;

        stop = fn(&e, &modified, private_data);

        DBG_DEBUG("entry[%zu]: modified=%d, e.stale=%d\n",
                  *i,
                  (int)modified,
                  (int)e.stale);

        if (e.stale) {
                if (DEBUGLEVEL>=10) {
                        DBG_DEBUG("share_mode_entry:\n");
                        NDR_PRINT_DEBUG(share_mode_entry, &e);
                }

                if (*i < *num_share_modes) {
                        memmove(blob.data,
                                blob.data + SHARE_MODE_ENTRY_SIZE,
                                (*num_share_modes - *i - 1) *
                                SHARE_MODE_ENTRY_SIZE);
                }
                *num_share_modes -= 1;
                *writeback = true;
                return stop;
        }

        if (modified) {
                if (DEBUGLEVEL>=10) {
                        DBG_DEBUG("share_mode_entry:\n");
                        NDR_PRINT_DEBUG(share_mode_entry, &e);
                }

                /*
                 * Make sure sorting order is kept intact
                 */
                SMB_ASSERT(server_id_equal(&e_pid, &e.pid));
                SMB_ASSERT(e_share_file_id == e.share_file_id);

                ndr_err = ndr_push_struct_into_fixed_blob(
                        &blob,
                        &e,
                        (ndr_push_flags_fn_t)
                        ndr_push_share_mode_entry);
                if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                        DBG_WARNING("ndr_push_share_mode_entry "
                                    "failed: %s\n",
                                    ndr_errstr(ndr_err));
                        /*
                         * Not much we can do, just ignore it
                         */
                }
                *i += 1;
                *writeback = true;
                return stop;
        }

        if (stop) {
                return true;
        }

        *i += 1;
        return false;
}

bool share_mode_forall_entries(
        struct share_mode_lock *lck,
        bool (*fn)(struct share_mode_entry *e,
                   bool *modified,
                   void *private_data),
        void *private_data)
{
        struct file_id id = share_mode_lock_file_id(lck);
        struct share_mode_data *d = NULL;
        TDB_DATA key = locking_key(&id);
        struct locking_tdb_data *ltdb = NULL;
        uint8_t *share_entries = NULL;
        size_t num_share_entries;
        bool writeback = false;
        NTSTATUS status;
        bool stop = false;
        size_t i;

        status = share_mode_lock_access_private_data(lck, &d);
        if (!NT_STATUS_IS_OK(status)) {
                struct file_id_buf id_buf;
                /* Any error recovery possible here ? */
                DBG_ERR("share_mode_lock_access_private_data() failed for "
                        "%s - %s\n",
                        file_id_str_buf(id, &id_buf),
                        nt_errstr(status));
                return false;
        }

        status = locking_tdb_data_fetch(key, talloc_tos(), &ltdb);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("locking_tdb_data_fetch failed: %s\n",
                        nt_errstr(status));
                return false;
        }
        DBG_DEBUG("num_share_modes=%zu\n", ltdb->num_share_entries);

        num_share_entries = ltdb->num_share_entries;
        share_entries = discard_const_p(uint8_t, ltdb->share_entries);

        i = 0;
        while (i<num_share_entries) {
                stop = share_mode_for_one_entry(
                        fn,
                        private_data,
                        &i,
                        share_entries,
                        &num_share_entries,
                        &writeback);
                if (stop) {
                        break;
                }
        }

        DBG_DEBUG("num_share_entries=%zu, writeback=%d\n",
                  num_share_entries,
                  (int)writeback);

        if (!writeback) {
                TALLOC_FREE(ltdb);
                return true;
        }

        if ((ltdb->num_share_entries != 0 ) && (num_share_entries == 0)) {
                /*
                 * This routine wiped all share entries, let
                 * share_mode_data_store() delete the record
                 */
                d->modified = true;
        }

        ltdb->num_share_entries = num_share_entries;
        ltdb->share_entries = share_entries;

        status = share_mode_data_ltdb_store(d, key, ltdb, NULL, 0);
        TALLOC_FREE(ltdb);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("share_mode_data_ltdb_store failed: %s\n",
                        nt_errstr(status));
                return false;
        }

        return true;
}

struct share_mode_count_entries_state {
        size_t num_share_modes;
        NTSTATUS status;
};

static void share_mode_count_entries_fn(
        struct server_id exclusive,
        size_t num_shared,
        const struct server_id *shared,
        const uint8_t *data,
        size_t datalen,
        void *private_data)
{
        struct share_mode_count_entries_state *state = private_data;
        struct locking_tdb_data ltdb = { 0 };
        bool ok;

        ok = locking_tdb_data_get(&ltdb, data, datalen);
        if (!ok) {
                DBG_WARNING("locking_tdb_data_get failed for %zu\n", datalen);
                state->status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                return;
        }
        state->num_share_modes = ltdb.num_share_entries;
        state->status = NT_STATUS_OK;
}

NTSTATUS share_mode_count_entries(struct file_id fid, size_t *num_share_modes)
{
        struct share_mode_count_entries_state state = {
                .status = NT_STATUS_NOT_FOUND,
        };
        NTSTATUS status;

        status = g_lock_dump(
                lock_ctx,
                locking_key(&fid),
                share_mode_count_entries_fn,
                &state);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_DEBUG("g_lock_dump failed: %s\n",
                          nt_errstr(status));
                return status;
        }
        if (!NT_STATUS_IS_OK(state.status)) {
                DBG_DEBUG("share_mode_count_entries_fn failed: %s\n",
                          nt_errstr(state.status));
                return state.status;
        }

        *num_share_modes = state.num_share_modes;
        return NT_STATUS_OK;
}

static bool share_mode_entry_do(
        struct share_mode_data *d,
        struct server_id pid,
        uint64_t share_file_id,
        void (*fn)(struct share_mode_entry *e,
                   size_t num_share_modes,
                   bool *modified,
                   void *private_data),
        void *private_data)
{
        TDB_DATA key = locking_key(&d->id);
        struct locking_tdb_data *ltdb = NULL;
        size_t idx;
        bool found = false;
        bool modified = false;
        struct share_mode_entry e;
        uint8_t *e_ptr = NULL;
        NTSTATUS status;
        bool ret = false;

        status = locking_tdb_data_fetch(key, talloc_tos(), &ltdb);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("locking_tdb_data_fetch failed: %s\n",
                        nt_errstr(status));
                return false;
        }
        DBG_DEBUG("num_share_modes=%zu\n", ltdb->num_share_entries);

        idx = share_mode_entry_find(
                ltdb->share_entries,
                ltdb->num_share_entries,
                pid,
                share_file_id,
                &e,
                &found);
        if (!found) {
                DBG_WARNING("Did not find share mode entry for %"PRIu64"\n",
                            share_file_id);
                goto done;
        }

        if (DEBUGLEVEL>=10) {
                DBG_DEBUG("entry[%zu]:\n", idx);
                NDR_PRINT_DEBUG(share_mode_entry, &e);
        }

        fn(&e, ltdb->num_share_entries, &modified, private_data);

        DBG_DEBUG("entry[%zu]: modified=%d, e.stale=%d\n",
                  idx,
                  (int)modified,
                  (int)e.stale);

        if (!e.stale && !modified) {
                ret = true;
                goto done;
        }

        e_ptr = discard_const_p(uint8_t, ltdb->share_entries) +
                idx * SHARE_MODE_ENTRY_SIZE;

        if (e.stale) {
                /*
                 * Move the rest down one entry
                 */
                size_t behind = ltdb->num_share_entries - idx - 1;
                if (behind != 0) {
                        memmove(e_ptr,
                                e_ptr + SHARE_MODE_ENTRY_SIZE,
                                behind * SHARE_MODE_ENTRY_SIZE);
                }
                ltdb->num_share_entries -= 1;

                if (ltdb->num_share_entries == 0) {
                        /*
                         * Tell share_mode_lock_destructor() to delete
                         * the whole record
                         */
                        d->modified = true;
                }

                if (DEBUGLEVEL>=10) {
                        DBG_DEBUG("share_mode_entry:\n");
                        NDR_PRINT_DEBUG(share_mode_entry, &e);
                }
        } else {
                struct share_mode_entry_buf buf;
                bool ok;

                if (ltdb->num_share_entries != 1) {
                        /*
                         * Make sure the sorting order stays intact
                         */
                        SMB_ASSERT(server_id_equal(&e.pid, &pid));
                        SMB_ASSERT(e.share_file_id == share_file_id);
                }

                ok = share_mode_entry_put(&e, &buf);
                if (!ok) {
                        DBG_DEBUG("share_mode_entry_put failed\n");
                        goto done;
                }
                memcpy(e_ptr, buf.buf, SHARE_MODE_ENTRY_SIZE);
        }

        status = share_mode_data_ltdb_store(d, key, ltdb, NULL, 0);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("share_mode_data_ltdb_store failed: %s\n",
                        nt_errstr(status));
                goto done;
        }

        ret = true;
done:
        TALLOC_FREE(ltdb);
        return ret;
}

struct del_share_mode_state {
        bool ok;
};

static void del_share_mode_fn(
        struct share_mode_entry *e,
        size_t num_share_modes,
        bool *modified,
        void *private_data)
{
        struct del_share_mode_state *state = private_data;
        e->stale = true;
        state->ok = true;
}

bool del_share_mode(struct share_mode_lock *lck, files_struct *fsp)
{
        struct del_share_mode_state state = { .ok = false };
        struct share_mode_data *d = NULL;
        NTSTATUS status;
        bool ok;

        status = share_mode_lock_access_private_data(lck, &d);
        if (!NT_STATUS_IS_OK(status)) {
                struct file_id id = share_mode_lock_file_id(lck);
                struct file_id_buf id_buf;
                /* Any error recovery possible here ? */
                DBG_ERR("share_mode_lock_access_private_data() failed for "
                        "%s %s - %s\n",
                        file_id_str_buf(id, &id_buf),
                        fsp_str_dbg(fsp),
                        nt_errstr(status));
                return false;
        }

        ok = share_mode_entry_do(
                d,
                messaging_server_id(fsp->conn->sconn->msg_ctx),
                fh_get_gen_id(fsp->fh),
                del_share_mode_fn,
                &state);
        if (!ok) {
                DBG_DEBUG("share_mode_entry_do failed\n");
                return false;
        }
        if (!state.ok) {
                DBG_DEBUG("del_share_mode_fn failed\n");
                return false;
        }
        return true;
}

struct remove_share_oplock_state {
        bool ok;
};

static void remove_share_oplock_fn(
        struct share_mode_entry *e,
        size_t num_share_modes,
        bool *modified,
        void *private_data)
{
        struct remove_share_oplock_state *state = private_data;

        e->op_type = NO_OPLOCK;
        *modified = true;
        state->ok = true;
}

bool remove_share_oplock(struct share_mode_lock *lck, files_struct *fsp)
{
        struct remove_share_oplock_state state = { .ok = false };
        struct share_mode_data *d = NULL;
        NTSTATUS status;
        bool ok;

        status = share_mode_lock_access_private_data(lck, &d);
        if (!NT_STATUS_IS_OK(status)) {
                struct file_id id = share_mode_lock_file_id(lck);
                struct file_id_buf id_buf;
                /* Any error recovery possible here ? */
                DBG_ERR("share_mode_lock_access_private_data() failed for "
                        "%s %s - %s\n",
                        file_id_str_buf(id, &id_buf),
                        fsp_str_dbg(fsp),
                        nt_errstr(status));
                return false;
        }

        ok = share_mode_entry_do(
                d,
                messaging_server_id(fsp->conn->sconn->msg_ctx),
                fh_get_gen_id(fsp->fh),
                remove_share_oplock_fn,
                &state);
        if (!ok) {
                DBG_DEBUG("share_mode_entry_do failed\n");
                return false;
        }
        if (!state.ok) {
                DBG_DEBUG("remove_share_oplock_fn failed\n");
                return false;
        }

        if (fsp->oplock_type == LEASE_OPLOCK) {
                remove_lease_if_stale(
                        lck,
                        fsp_client_guid(fsp),
                        &fsp->lease->lease.lease_key);
        }

        share_mode_wakeup_waiters(fsp->file_id);

        return true;
}

struct downgrade_share_oplock_state {
        bool ok;
};

static void downgrade_share_oplock_fn(
        struct share_mode_entry *e,
        size_t num_share_modes,
        bool *modified,
        void *private_data)
{
        struct downgrade_share_oplock_state *state = private_data;

        e->op_type = LEVEL_II_OPLOCK;
        *modified = true;
        state->ok = true;
}

bool downgrade_share_oplock(struct share_mode_lock *lck, files_struct *fsp)
{
        struct downgrade_share_oplock_state state = { .ok = false };
        struct share_mode_data *d = NULL;
        NTSTATUS status;
        bool ok;

        status = share_mode_lock_access_private_data(lck, &d);
        if (!NT_STATUS_IS_OK(status)) {
                struct file_id id = share_mode_lock_file_id(lck);
                struct file_id_buf id_buf;
                /* Any error recovery possible here ? */
                DBG_ERR("share_mode_lock_access_private_data() failed for "
                        "%s %s - %s\n",
                        file_id_str_buf(id, &id_buf),
                        fsp_str_dbg(fsp),
                        nt_errstr(status));
                return false;
        }

        ok = share_mode_entry_do(
                d,
                messaging_server_id(fsp->conn->sconn->msg_ctx),
                fh_get_gen_id(fsp->fh),
                downgrade_share_oplock_fn,
                &state);
        if (!ok) {
                DBG_DEBUG("share_mode_entry_do failed\n");
                return false;
        }
        if (!state.ok) {
                DBG_DEBUG("downgrade_share_oplock_fn failed\n");
                return false;
        }

        d->flags |= SHARE_MODE_LEASE_READ;
        d->modified = true;

        return true;
}

bool mark_share_mode_disconnected(struct share_mode_lock *lck,
                                  struct files_struct *fsp)
{
        struct server_id disconnected_pid = { .pid = 0 };
        bool ok;

        if (fsp->op == NULL) {
                return false;
        }
        if (!fsp->op->global->durable) {
                return false;
        }

        server_id_set_disconnected(&disconnected_pid);

        ok = reset_share_mode_entry(
                lck,
                messaging_server_id(fsp->conn->sconn->msg_ctx),
                fh_get_gen_id(fsp->fh),
                disconnected_pid,
                UINT64_MAX,
                fsp->op->global->open_persistent_id);

        return ok;
}

bool reset_share_mode_entry(
        struct share_mode_lock *lck,
        struct server_id old_pid,
        uint64_t old_share_file_id,
        struct server_id new_pid,
        uint64_t new_mid,
        uint64_t new_share_file_id)
{
        struct file_id id = share_mode_lock_file_id(lck);
        struct share_mode_data *d = NULL;
        TDB_DATA key = locking_key(&id);
        struct locking_tdb_data *ltdb = NULL;
        struct share_mode_entry e;
        struct share_mode_entry_buf e_buf;
        NTSTATUS status;
        int cmp;
        bool ret = false;
        bool ok;

        status = share_mode_lock_access_private_data(lck, &d);
        if (!NT_STATUS_IS_OK(status)) {
                struct file_id_buf id_buf;
                /* Any error recovery possible here ? */
                DBG_ERR("share_mode_lock_access_private_data() failed for "
                        "%s - %s\n",
                        file_id_str_buf(id, &id_buf),
                        nt_errstr(status));
                return false;
        }

        status = locking_tdb_data_fetch(key, talloc_tos(), &ltdb);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("locking_tdb_data_fetch failed: %s\n",
                        nt_errstr(status));
                return false;
        }

        if (ltdb->num_share_entries != 1) {
                DBG_DEBUG("num_share_modes=%zu\n", ltdb->num_share_entries);
                goto done;
        }

        ok = share_mode_entry_get(ltdb->share_entries, &e);
        if (!ok) {
                DBG_WARNING("share_mode_entry_get failed\n");
                goto done;
        }

        cmp = share_mode_entry_cmp(
                old_pid, old_share_file_id, e.pid, e.share_file_id);
        if (cmp != 0) {
                struct server_id_buf tmp1, tmp2;
                DBG_WARNING("Expected pid=%s, file_id=%"PRIu64", "
                            "got pid=%s, file_id=%"PRIu64"\n",
                            server_id_str_buf(old_pid, &tmp1),
                            old_share_file_id,
                            server_id_str_buf(e.pid, &tmp2),
                            e.share_file_id);
                goto done;
        }

        e.pid = new_pid;
        if (new_mid != UINT64_MAX) {
                e.op_mid = new_mid;
        }
        e.share_file_id = new_share_file_id;

        ok = share_mode_entry_put(&e, &e_buf);
        if (!ok) {
                DBG_WARNING("share_mode_entry_put failed\n");
                goto done;
        }

        ltdb->share_entries = e_buf.buf;

        d->modified = true;

        status = share_mode_data_ltdb_store(d, key, ltdb, NULL, 0);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("share_mode_data_ltdb_store failed: %s\n",
                        nt_errstr(status));
                goto done;
        }

        ret = true;
done:
        TALLOC_FREE(ltdb);
        return ret;
}

struct share_mode_do_locked_vfs_denied_state {
        struct file_id id;
        share_mode_do_locked_vfs_fn_t fn;
        void *private_data;
        const char *location;
        NTSTATUS status;
};

static void share_mode_do_locked_vfs_denied_fn(struct g_lock_lock_cb_state *glck,
                                               void *cb_private)
{
        struct share_mode_do_locked_vfs_denied_state *state =
                (struct share_mode_do_locked_vfs_denied_state *)cb_private;
        struct smb_vfs_deny_state vfs_deny = {};
        struct share_mode_lock lck;

        if (glck != NULL) {
                current_share_mode_glck = glck;
        }

        state->status = get_share_mode_lock_internal(state->id,
                                                     NULL,  /* servicepath */
                                                     NULL,  /* smb_fname */
                                                     NULL,  /* old_write_time */
                                                     &lck);
        if (!NT_STATUS_IS_OK(state->status)) {
                DBG_GET_SHARE_MODE_LOCK(state->status,
                        "get_share_mode_lock_internal failed: %s\n",
                        nt_errstr(state->status));
                if (glck != NULL) {
                        g_lock_lock_cb_unlock(glck);
                        current_share_mode_glck = NULL;
                }
                return;
        }

        _smb_vfs_deny_push(&vfs_deny, state->location);
        state->fn(&lck, state->private_data);
        _smb_vfs_deny_pop(&vfs_deny, state->location);

        state->status = put_share_mode_lock_internal(&lck);
        if (!NT_STATUS_IS_OK(state->status)) {
                DBG_ERR("put_share_mode_lock_internal failed: %s\n",
                        nt_errstr(state->status));
                smb_panic("put_share_mode_lock_internal failed\n");
                return;
        }

        if (glck != NULL) {
                g_lock_lock_cb_unlock(glck);
                current_share_mode_glck = NULL;
        }
        return;
}

/**
 * @brief Run @fn protected with G_LOCK_WRITE in the given file_id
 *
 * @fn is NOT allowed to call SMB_VFS_* or similar functions,
 * which may block for some time in the kernel.
 *
 * There must be at least one share_mode_entry, otherwise
 * NT_STATUS_NOT_FOUND is returned.
 *
 * @param[in]  id           The key for the share_mode record.
 * @param[in]  fn           The function to run under the g_lock.
 * @param[in]  private_date A private pointer passed to @fn.
 */
NTSTATUS _share_mode_do_locked_vfs_denied(
        struct file_id id,
        share_mode_do_locked_vfs_fn_t fn,
        void *private_data,
        const char *location)
{
        struct share_mode_do_locked_vfs_denied_state state = {
                .id = id,
                .fn = fn,
                .private_data = private_data,
                .location = location,
        };

        if (share_mode_lock_key_refcount == 0) {
                TDB_DATA key = locking_key(&id);
                NTSTATUS status;

                share_mode_lock_skip_g_lock = true;
                status = g_lock_lock(
                        lock_ctx,
                        key,
                        G_LOCK_WRITE,
                        (struct timeval) { .tv_sec = 3600 },
                        share_mode_do_locked_vfs_denied_fn,
                        &state);
                share_mode_lock_skip_g_lock = false;
                if (!NT_STATUS_IS_OK(status)) {
                        DBG_DEBUG("g_lock_lock failed: %s\n",
                                  nt_errstr(status));
                        return status;
                }
                return state.status;
        }

        share_mode_do_locked_vfs_denied_fn(NULL, &state);

        return state.status;
}

/**
 * @brief Run @fn protected with G_LOCK_WRITE in the given file_id
 *
 * @fn is allowed to call SMB_VFS_* or similar functions,
 * which may block for some time in the kernel.
 *
 * There must be at least one share_mode_entry, otherwise
 * NT_STATUS_NOT_FOUND is returned.
 *
 * @param[in]  id           The key for the share_mode record.
 * @param[in]  fn           The function to run under the g_lock.
 * @param[in]  private_date A private pointer passed to @fn.
 */
NTSTATUS _share_mode_do_locked_vfs_allowed(
        struct file_id id,
        share_mode_do_locked_vfs_fn_t fn,
        void *private_data,
        const char *location)
{
        struct share_mode_lock lck;
        NTSTATUS status;

        smb_vfs_assert_allowed();

        status = get_share_mode_lock_internal(id,
                                              NULL,  /* servicepath */
                                              NULL,  /* smb_fname */
                                              NULL,  /* old_write_time */
                                              &lck);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_GET_SHARE_MODE_LOCK(status,
                        "get_share_mode_lock_internal failed: %s\n",
                        nt_errstr(status));
                return status;
        }

        fn(&lck, private_data);

        status = put_share_mode_lock_internal(&lck);
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("put_share_mode_lock_internal failed: %s\n",
                        nt_errstr(status));
                smb_panic("put_share_mode_lock_internal failed\n");
                return status;
        }

        return NT_STATUS_OK;
}

struct share_mode_entry_prepare_lock_state {
        struct file_id id;
        const char *servicepath;
        const struct smb_filename *smb_fname;
        const struct timespec *old_write_time;
        share_mode_entry_prepare_lock_fn_t fn;
        void *private_data;
        const char *location;
        bool keep_locked;
        struct share_mode_lock *lck;
        NTSTATUS status;
};

static void share_mode_entry_prepare_lock_fn(struct g_lock_lock_cb_state *glck,
                                             void *cb_private)
{
        struct share_mode_entry_prepare_lock_state *state =
                (struct share_mode_entry_prepare_lock_state *)cb_private;
        struct smb_vfs_deny_state vfs_deny = {};

        SMB_ASSERT(glck != NULL);
        current_share_mode_glck = glck;

        state->status = get_share_mode_lock_internal(state->id,
                                                     state->servicepath,
                                                     state->smb_fname,
                                                     state->old_write_time,
                                                     state->lck);
        if (!NT_STATUS_IS_OK(state->status)) {
                /* no DBG_GET_SHARE_MODE_LOCK here! */
                DBG_ERR("get_share_mode_lock_internal failed: %s\n",
                        nt_errstr(state->status));
                g_lock_lock_cb_unlock(glck);
                current_share_mode_glck = NULL;
                return;
        }

        _smb_vfs_deny_push(&vfs_deny, state->location);
        state->fn(state->lck, &state->keep_locked, state->private_data);
        _smb_vfs_deny_pop(&vfs_deny, state->location);

        if (state->keep_locked) {
                current_share_mode_glck = NULL;
                return;
        }

        state->status = put_share_mode_lock_internal(state->lck);
        if (!NT_STATUS_IS_OK(state->status)) {
                DBG_ERR("put_share_mode_lock_internal failed: %s\n",
                        nt_errstr(state->status));
                smb_panic("put_share_mode_lock_internal failed\n");
                return;
        }

        g_lock_lock_cb_unlock(glck);
        current_share_mode_glck = NULL;
        return;
}

NTSTATUS _share_mode_entry_prepare_lock(
        struct share_mode_entry_prepare_state *prepare_state,
        struct file_id id,
        const char *servicepath,
        const struct smb_filename *smb_fname,
        const struct timespec *old_write_time,
        share_mode_entry_prepare_lock_fn_t fn,
        void *private_data,
        const char *location)
{
        struct share_mode_entry_prepare_lock_state state = {
                .id = id,
                .servicepath = servicepath,
                .smb_fname = smb_fname,
                .old_write_time = old_write_time,
                .fn = fn,
                .private_data = private_data,
                .location = location,
        };
        TDB_DATA key = locking_key(&id);
        NTSTATUS status;

        SMB_ASSERT(share_mode_lock_key_refcount == 0);

        SMB_ASSERT(__SHARE_MODE_LOCK_SPACE == sizeof(struct share_mode_lock));

        *prepare_state = (struct share_mode_entry_prepare_state) {
                .__fid = id,
                .__lck_ptr = &prepare_state->__lck_space,
        };

        state.lck = prepare_state->__lck_ptr;

        share_mode_lock_skip_g_lock = true;
        status = g_lock_lock(
                lock_ctx,
                key,
                G_LOCK_WRITE,
                (struct timeval) { .tv_sec = 3600 },
                share_mode_entry_prepare_lock_fn,
                &state);
        share_mode_lock_skip_g_lock = false;
        if (!state.keep_locked) {
                prepare_state->__lck_ptr = NULL;
        }
        if (!NT_STATUS_IS_OK(status)) {
                DBG_DEBUG("g_lock_lock failed: %s\n",
                          nt_errstr(status));
                return status;
        }

        return state.status;
}

struct share_mode_entry_prepare_unlock_state {
        struct file_id id;
        share_mode_entry_prepare_unlock_fn_t fn;
        void *private_data;
        const char *location;
        struct share_mode_lock *lck;
        NTSTATUS status;
};

static void share_mode_entry_prepare_unlock_existing_fn(
        struct share_mode_entry_prepare_unlock_state *state)
{
        if (state->fn != NULL) {
                struct smb_vfs_deny_state vfs_deny = {};

                _smb_vfs_deny_push(&vfs_deny, state->location);
                state->fn(state->lck, state->private_data);
                _smb_vfs_deny_pop(&vfs_deny, state->location);
        }

        state->status = put_share_mode_lock_internal(state->lck);
        if (!NT_STATUS_IS_OK(state->status)) {
                DBG_ERR("put_share_mode_lock_internal failed: %s\n",
                        nt_errstr(state->status));
                smb_panic("put_share_mode_lock_internal failed\n");
                return;
        }

        return;
}

static void share_mode_entry_prepare_unlock_relock_fn(struct g_lock_lock_cb_state *glck,
                                                      void *cb_private)
{
        struct share_mode_entry_prepare_unlock_state *state =
                (struct share_mode_entry_prepare_unlock_state *)cb_private;
        struct smb_vfs_deny_state vfs_deny = {};

        SMB_ASSERT(glck != NULL);
        current_share_mode_glck = glck;

        state->status = get_share_mode_lock_internal(state->id,
                                                     NULL,  /* servicepath */
                                                     NULL,  /* smb_fname */
                                                     NULL,  /* old_write_time */
                                                     state->lck);
        if (!NT_STATUS_IS_OK(state->status)) {
                /* no DBG_GET_SHARE_MODE_LOCK here! */
                DBG_ERR("get_share_mode_lock_internal failed: %s\n",
                        nt_errstr(state->status));
                g_lock_lock_cb_unlock(glck);
                current_share_mode_glck = NULL;
                return;
        }

        _smb_vfs_deny_push(&vfs_deny, state->location);
        state->fn(state->lck, state->private_data);
        _smb_vfs_deny_pop(&vfs_deny, state->location);

        state->status = put_share_mode_lock_internal(state->lck);
        if (!NT_STATUS_IS_OK(state->status)) {
                DBG_ERR("put_share_mode_lock_internal failed: %s\n",
                        nt_errstr(state->status));
                smb_panic("put_share_mode_lock_internal failed\n");
                return;
        }

        g_lock_lock_cb_unlock(glck);
        current_share_mode_glck = NULL;
        return;
}

NTSTATUS _share_mode_entry_prepare_unlock(
        struct share_mode_entry_prepare_state *prepare_state,
        share_mode_entry_prepare_unlock_fn_t fn,
        void *private_data,
        const char *location)
{
        struct share_mode_entry_prepare_unlock_state state = {
                .id = prepare_state->__fid,
                .fn = fn,
                .private_data = private_data,
                .location = location,
        };
        TDB_DATA key = locking_key(&prepare_state->__fid);
        NTSTATUS status;

        if (prepare_state->__lck_ptr != NULL) {
                /*
                 * With an existing lock, we just run the unlock prepare
                 * function following by the unlock.
                 */

                SMB_ASSERT(share_mode_lock_key_refcount == 1);

                state.lck = prepare_state->__lck_ptr;
                prepare_state->__lck_ptr = NULL;

                share_mode_entry_prepare_unlock_existing_fn(&state);
                return state.status;
        }

        /*
         * No existing lock, which means
         * _share_mode_entry_prepare_lock() didn't steal
         * the lock...
         */
        SMB_ASSERT(share_mode_lock_key_refcount == 0);

        if (fn == NULL) {
                /*
                 * Without an existing lock and without
                 * a prepare function there's nothing to
                 * do...
                 */
                return NT_STATUS_OK;
        }

        /*
         * In order to run the unlock prepare function
         * we need to relock the entry.
         */
        state.lck = &prepare_state->__lck_space;

        share_mode_lock_skip_g_lock = true;
        status = g_lock_lock(
                lock_ctx,
                key,
                G_LOCK_WRITE,
                (struct timeval) { .tv_sec = 3600 },
                share_mode_entry_prepare_unlock_relock_fn,
                &state);
        share_mode_lock_skip_g_lock = false;
        if (!NT_STATUS_IS_OK(status)) {
                DBG_ERR("g_lock_lock failed: %s\n",
                        nt_errstr(status));
                return status;
        }

        return state.status;
}