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[Samba.git] / lib / dbwrap / dbwrap.c

/*
   Unix SMB/CIFS implementation.
   Database interface wrapper
   Copyright (C) Jim McDonough <jmcd@us.ibm.com> 2006

   Major code contributions from Aleksey Fedoseev (fedoseev@ru.ibm.com)

   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/>.
*/

#include "replace.h"
#include "lib/util/debug.h"
#include "lib/util/fault.h"
#include "lib/util/talloc_stack.h"
#include "dbwrap/dbwrap.h"
#include "dbwrap/dbwrap_private.h"
#include "lib/util/util_tdb.h"
#include "lib/util/tevent_ntstatus.h"

/*
 * Fall back using fetch if no genuine exists operation is provided
 */

static int dbwrap_fallback_exists(struct db_context *db, TDB_DATA key)
{
        NTSTATUS status = dbwrap_parse_record(db, key, NULL, NULL);
        return NT_STATUS_IS_OK(status) ? 1 : 0;
}

static int delete_record(struct db_record *rec, void *data)
{
        NTSTATUS status = dbwrap_record_delete(rec);
        return NT_STATUS_IS_OK(status) ? 0 : -1;
}

/*
 * Fallback wipe implementation using traverse and delete if no genuine
 * wipe operation is provided
 */
static int dbwrap_fallback_wipe(struct db_context *db)
{
        NTSTATUS status = dbwrap_trans_traverse(db, delete_record, NULL);
        return NT_STATUS_IS_OK(status) ? 0 : -1;
}

static int do_nothing(struct db_record *rec, void *unused)
{
        return 0;
}

/*
 * Fallback check operation: just traverse.
 */
static int dbwrap_fallback_check(struct db_context *db)
{
        NTSTATUS status = dbwrap_traverse_read(db, do_nothing, NULL, NULL);
        return NT_STATUS_IS_OK(status) ? 0 : -1;
}

/*
 * Wrapper functions for the backend methods
 */

TDB_DATA dbwrap_record_get_key(const struct db_record *rec)
{
        return rec->key;
}

TDB_DATA dbwrap_record_get_value(const struct db_record *rec)
{
        return rec->value;
}

NTSTATUS dbwrap_record_storev(struct db_record *rec,
                              const TDB_DATA *dbufs, int num_dbufs, int flags)
{
        NTSTATUS status;

        status = rec->storev(rec, dbufs, num_dbufs, flags);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }
        return NT_STATUS_OK;
}

NTSTATUS dbwrap_record_store(struct db_record *rec, TDB_DATA data, int flags)
{
        return dbwrap_record_storev(rec, &data, 1, flags);
}

NTSTATUS dbwrap_record_delete(struct db_record *rec)
{
        NTSTATUS status;

        status = rec->delete_rec(rec);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }
        return NT_STATUS_OK;
}

static void debug_lock_order(int level, struct db_context *dbs[])
{
        int i;
        DEBUG(level, ("lock order: "));
        for (i=0; i<DBWRAP_LOCK_ORDER_MAX; i++) {
                DEBUGADD(level, (" %d:%s", i + 1, dbs[i] ? dbs[i]->name : "<none>"));
        }
        DEBUGADD(level, ("\n"));
}

static void dbwrap_lock_order_lock(struct db_context *db,
                                   struct db_context ***lockptr)
{
        static struct db_context *locked_dbs[DBWRAP_LOCK_ORDER_MAX];
        int idx;

        DBG_INFO("check lock order %d for %s\n", (int)db->lock_order,
                 db->name);

        if (!DBWRAP_LOCK_ORDER_VALID(db->lock_order)) {
                DBG_ERR("Invalid lock order %d of %s\n",
                        (int)db->lock_order, db->name);
                smb_panic("lock order violation");
        }

        for (idx=db->lock_order-1; idx<DBWRAP_LOCK_ORDER_MAX; idx++) {
                if (locked_dbs[idx] != NULL) {
                        DBG_ERR("Lock order violation: Trying %s at %d while "
                                "%s at %d is locked\n",
                                db->name, (int)db->lock_order,
                                locked_dbs[idx]->name, idx + 1);
                        debug_lock_order(0, locked_dbs);
                        smb_panic("lock order violation");
                }
        }

        locked_dbs[db->lock_order-1] = db;
        *lockptr = &locked_dbs[db->lock_order-1];

        debug_lock_order(10, locked_dbs);
}

static void dbwrap_lock_order_unlock(struct db_context *db,
                                     struct db_context **lockptr)
{
        DBG_INFO("release lock order %d for %s\n",
                 (int)db->lock_order, db->name);

        if (*lockptr == NULL) {
                DBG_ERR("db %s at order %d unlocked\n", db->name,
                        (int)db->lock_order);
                smb_panic("lock order violation");
        }

        if (*lockptr != db) {
                DBG_ERR("locked db at lock order %d is %s, expected %s\n",
                        (int)(*lockptr)->lock_order, (*lockptr)->name,
                        db->name);
                smb_panic("lock order violation");
        }

        *lockptr = NULL;
}

struct dbwrap_lock_order_state {
        struct db_context *db;
        struct db_context **lockptr;
};

static int dbwrap_lock_order_state_destructor(
        struct dbwrap_lock_order_state *s)
{
        dbwrap_lock_order_unlock(s->db, s->lockptr);
        return 0;
}

static struct dbwrap_lock_order_state *dbwrap_check_lock_order(
        struct db_context *db, TALLOC_CTX *mem_ctx)
{
        struct dbwrap_lock_order_state *state;

        state = talloc(mem_ctx, struct dbwrap_lock_order_state);
        if (state == NULL) {
                DBG_WARNING("talloc failed\n");
                return NULL;
        }
        state->db = db;

        dbwrap_lock_order_lock(db, &state->lockptr);
        talloc_set_destructor(state, dbwrap_lock_order_state_destructor);

        return state;
}

static struct db_record *dbwrap_fetch_locked_internal(
        struct db_context *db, TALLOC_CTX *mem_ctx, TDB_DATA key,
        struct db_record *(*db_fn)(struct db_context *db, TALLOC_CTX *mem_ctx,
                                   TDB_DATA key))
{
        struct db_record *rec;
        struct dbwrap_lock_order_state *lock_order = NULL;

        if (db->lock_order != DBWRAP_LOCK_ORDER_NONE) {
                lock_order = dbwrap_check_lock_order(db, mem_ctx);
                if (lock_order == NULL) {
                        return NULL;
                }
        }
        rec = db_fn(db, mem_ctx, key);
        if (rec == NULL) {
                TALLOC_FREE(lock_order);
                return NULL;
        }
        (void)talloc_steal(rec, lock_order);
        rec->db = db;
        return rec;
}

struct db_record *dbwrap_fetch_locked(struct db_context *db,
                                      TALLOC_CTX *mem_ctx,
                                      TDB_DATA key)
{
        return dbwrap_fetch_locked_internal(db, mem_ctx, key,
                                            db->fetch_locked);
}

struct db_record *dbwrap_try_fetch_locked(struct db_context *db,
                                      TALLOC_CTX *mem_ctx,
                                      TDB_DATA key)
{
        return dbwrap_fetch_locked_internal(
                db, mem_ctx, key,
                db->try_fetch_locked
                ? db->try_fetch_locked : db->fetch_locked);
}

struct db_context *dbwrap_record_get_db(struct db_record *rec)
{
        return rec->db;
}

struct dbwrap_fetch_state {
        TALLOC_CTX *mem_ctx;
        TDB_DATA data;
};

static void dbwrap_fetch_parser(TDB_DATA key, TDB_DATA data,
                                void *private_data)
{
        struct dbwrap_fetch_state *state =
                (struct dbwrap_fetch_state *)private_data;

        state->data.dsize = data.dsize;
        state->data.dptr = (uint8_t *)talloc_memdup(state->mem_ctx, data.dptr,
                                                    data.dsize);
}

NTSTATUS dbwrap_fetch(struct db_context *db, TALLOC_CTX *mem_ctx,
                      TDB_DATA key, TDB_DATA *value)
{
        struct dbwrap_fetch_state state;
        NTSTATUS status;

        if (value == NULL) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        state.mem_ctx = mem_ctx;

        status = dbwrap_parse_record(db, key, dbwrap_fetch_parser, &state);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }
        if ((state.data.dsize != 0) && (state.data.dptr == NULL)) {
                return NT_STATUS_NO_MEMORY;
        }
        *value = state.data;
        return NT_STATUS_OK;
}

bool dbwrap_exists(struct db_context *db, TDB_DATA key)
{
        int result;
        if (db->exists != NULL) {
                result = db->exists(db, key);
        } else {
                result = dbwrap_fallback_exists(db,key);
        }
        return (result == 1);
}

struct dbwrap_store_state {
        TDB_DATA data;
        int flags;
        NTSTATUS status;
};

static void dbwrap_store_fn(struct db_record *rec, void *private_data)
{
        struct dbwrap_store_state *state = private_data;
        state->status = dbwrap_record_store(rec, state->data, state->flags);
}

NTSTATUS dbwrap_store(struct db_context *db, TDB_DATA key,
                      TDB_DATA data, int flags)
{
        struct dbwrap_store_state state = { .data = data, .flags = flags };
        NTSTATUS status;

        status = dbwrap_do_locked(db, key, dbwrap_store_fn, &state);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        return state.status;
}

struct dbwrap_delete_state {
        NTSTATUS status;
};

static void dbwrap_delete_fn(struct db_record *rec, void *private_data)
{
        struct dbwrap_delete_state *state = private_data;
        state->status = dbwrap_record_delete(rec);
}

NTSTATUS dbwrap_delete(struct db_context *db, TDB_DATA key)
{
        struct dbwrap_delete_state state;
        NTSTATUS status;

        status = dbwrap_do_locked(db, key, dbwrap_delete_fn, &state);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        return state.status;
}

NTSTATUS dbwrap_traverse(struct db_context *db,
                         int (*f)(struct db_record*, void*),
                         void *private_data,
                         int *count)
{
        int ret = db->traverse(db, f, private_data);

        if (ret < 0) {
                return NT_STATUS_INTERNAL_DB_CORRUPTION;
        }

        if (count != NULL) {
                *count = ret;
        }

        return NT_STATUS_OK;
}

NTSTATUS dbwrap_traverse_read(struct db_context *db,
                              int (*f)(struct db_record*, void*),
                              void *private_data,
                              int *count)
{
        int ret = db->traverse_read(db, f, private_data);

        if (ret < 0) {
                return NT_STATUS_INTERNAL_DB_CORRUPTION;
        }

        if (count != NULL) {
                *count = ret;
        }

        return NT_STATUS_OK;
}

static void dbwrap_null_parser(TDB_DATA key, TDB_DATA val, void* data)
{
        return;
}

NTSTATUS dbwrap_parse_record(struct db_context *db, TDB_DATA key,
                             void (*parser)(TDB_DATA key, TDB_DATA data,
                                            void *private_data),
                             void *private_data)
{
        if (parser == NULL) {
                parser = dbwrap_null_parser;
        }
        return db->parse_record(db, key, parser, private_data);
}

struct dbwrap_parse_record_state {
        struct db_context *db;
        TDB_DATA key;
        uint8_t _keybuf[64];
};

static void dbwrap_parse_record_done(struct tevent_req *subreq);

struct tevent_req *dbwrap_parse_record_send(
        TALLOC_CTX *mem_ctx,
        struct tevent_context *ev,
        struct db_context *db,
        TDB_DATA key,
        void (*parser)(TDB_DATA key, TDB_DATA data, void *private_data),
        void *private_data,
        enum dbwrap_req_state *req_state)
{
        struct tevent_req *req = NULL;
        struct tevent_req *subreq = NULL;
        struct dbwrap_parse_record_state *state = NULL;
        NTSTATUS status;

        req = tevent_req_create(mem_ctx, &state, struct dbwrap_parse_record_state);
        if (req == NULL) {
                *req_state = DBWRAP_REQ_ERROR;
                return NULL;
        }

        *state = (struct dbwrap_parse_record_state) {
                .db = db,
        };

        if (parser == NULL) {
                parser = dbwrap_null_parser;
        }

        *req_state = DBWRAP_REQ_INIT;

        if (db->parse_record_send == NULL) {
                /*
                 * Backend doesn't implement async version, call sync one
                 */
                status = db->parse_record(db, key, parser, private_data);
                if (tevent_req_nterror(req, status)) {
                        *req_state = DBWRAP_REQ_DONE;
                        return tevent_req_post(req, ev);
                }

                *req_state = DBWRAP_REQ_DONE;
                tevent_req_done(req);
                return tevent_req_post(req, ev);
        }

        /*
         * Copy the key into our state ensuring the key data buffer is always
         * available to the all dbwrap backend over the entire lifetime of the
         * async request. Otherwise the caller might have free'd the key buffer.
         */
        if (key.dsize > sizeof(state->_keybuf)) {
                state->key.dptr = talloc_memdup(state, key.dptr, key.dsize);
                if (tevent_req_nomem(state->key.dptr, req)) {
                        return tevent_req_post(req, ev);
                }
        } else {
                memcpy(state->_keybuf, key.dptr, key.dsize);
                state->key.dptr = state->_keybuf;
        }
        state->key.dsize = key.dsize;

        subreq = db->parse_record_send(state,
                                       ev,
                                       db,
                                       state->key,
                                       parser,
                                       private_data,
                                       req_state);
        if (tevent_req_nomem(subreq, req)) {
                *req_state = DBWRAP_REQ_ERROR;
                return tevent_req_post(req, ev);
        }

        tevent_req_set_callback(subreq,
                                dbwrap_parse_record_done,
                                req);
        return req;
}

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

        status = state->db->parse_record_recv(subreq);
        TALLOC_FREE(subreq);
        if (!NT_STATUS_IS_OK(status)) {
                tevent_req_nterror(req, status);
                return;
        }

        tevent_req_done(req);
        return;
}

NTSTATUS dbwrap_parse_record_recv(struct tevent_req *req)
{
        return tevent_req_simple_recv_ntstatus(req);
}

NTSTATUS dbwrap_do_locked(struct db_context *db, TDB_DATA key,
                          void (*fn)(struct db_record *rec,
                                     void *private_data),
                          void *private_data)
{
        struct db_record *rec;

        if (db->do_locked != NULL) {
                struct db_context **lockptr;
                NTSTATUS status;

                if (db->lock_order != DBWRAP_LOCK_ORDER_NONE) {
                        dbwrap_lock_order_lock(db, &lockptr);
                }

                status = db->do_locked(db, key, fn, private_data);

                if (db->lock_order != DBWRAP_LOCK_ORDER_NONE) {
                        dbwrap_lock_order_unlock(db, lockptr);
                }

                return status;
        }

        rec = dbwrap_fetch_locked(db, db, key);
        if (rec == NULL) {
                return NT_STATUS_NO_MEMORY;
        }

        fn(rec, private_data);

        TALLOC_FREE(rec);

        return NT_STATUS_OK;
}

int dbwrap_wipe(struct db_context *db)
{
        if (db->wipe == NULL) {
                return dbwrap_fallback_wipe(db);
        }
        return db->wipe(db);
}

int dbwrap_check(struct db_context *db)
{
        if (db->check == NULL) {
                return dbwrap_fallback_check(db);
        }
        return db->check(db);
}

int dbwrap_get_seqnum(struct db_context *db)
{
        return db->get_seqnum(db);
}

int dbwrap_transaction_start(struct db_context *db)
{
        if (!db->persistent) {
                /*
                 * dbwrap_ctdb has two different data models for persistent
                 * and non-persistent databases. Transactions are supported
                 * only for the persistent databases. This check is here to
                 * prevent breakages of the cluster case, autobuild at this
                 * point only tests non-clustered Samba. Before removing this
                 * check, please make sure that this facility has also been
                 * added to dbwrap_ctdb.
                 *
                 * Thanks, vl
                 */
                DEBUG(1, ("transactions not supported on non-persistent "
                          "database %s\n", db->name));
                return -1;
        }
        return db->transaction_start(db);
}

NTSTATUS dbwrap_transaction_start_nonblock(struct db_context *db)
{
        if (db->transaction_start_nonblock) {
                return db->transaction_start_nonblock(db);
        } else {
                return dbwrap_transaction_start(db) == 0 ? NT_STATUS_OK
                        : NT_STATUS_UNSUCCESSFUL;
        }
}

int dbwrap_transaction_commit(struct db_context *db)
{
        return db->transaction_commit(db);
}

int dbwrap_transaction_cancel(struct db_context *db)
{
        return db->transaction_cancel(db);
}

size_t dbwrap_db_id(struct db_context *db, uint8_t *id, size_t idlen)
{
        return db->id(db, id, idlen);
}

bool dbwrap_is_persistent(struct db_context *db)
{
        return db->persistent;
}

const char *dbwrap_name(struct db_context *db)
{
        return db->name;
}

static ssize_t tdb_data_buf(const TDB_DATA *dbufs, int num_dbufs,
                            uint8_t *buf, size_t buflen)
{
        size_t needed = 0;
        uint8_t *p = buf;
        int i;

        for (i=0; i<num_dbufs; i++) {
                size_t thislen = dbufs[i].dsize;
                size_t tmp;

                tmp = needed + thislen;
                if (tmp < needed) {
                        /* wrap */
                        return -1;
                }
                needed = tmp;

                if (needed <= buflen) {
                        memcpy(p, dbufs[i].dptr, thislen);
                        p += thislen;
                }
        }

        return needed;
}


TDB_DATA dbwrap_merge_dbufs(TALLOC_CTX *mem_ctx,
                            const TDB_DATA *dbufs, int num_dbufs)
{
        ssize_t len = tdb_data_buf(dbufs, num_dbufs, NULL, 0);
        uint8_t *buf;

        if (len == -1) {
                return (TDB_DATA) {0};
        }

        buf = talloc_array(mem_ctx, uint8_t, len);
        if (buf == NULL) {
                return (TDB_DATA) {0};
        }

        tdb_data_buf(dbufs, num_dbufs, buf, len);

        return (TDB_DATA) { .dptr = buf, .dsize = len };
}