/* Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

/* Overview of what this is and does:

 * http://www.apache.org/~niq/dbd.html

 * or

 * http://apache.webthing.com/database/

 */

#include "apr_reslist.h"

#include "apr_strings.h"

#include "apr_hash.h"

#include "apr_tables.h"

#include "apr_lib.h"

#include "apr_dbd.h"

#define APR_WANT_MEMFUNC

#define APR_WANT_STRFUNC

#include "apr_want.h"

#include "http_protocol.h"

#include "http_config.h"

#include "http_log.h"

#include "http_request.h"

#include "mod_dbd.h"

extern module AP_MODULE_DECLARE_DATA dbd_module;

APR_IMPLEMENT_OPTIONAL_HOOK_RUN_ALL(dbd, DBD, apr_status_t, post_connect,

                                    (apr_pool_t *pool, dbd_cfg_t *cfg,

                                    ap_dbd_t *dbd),

                                    (pool, cfg, dbd), OK, DECLINED)

/************ svr cfg: manage db connection pool ****************/

#define NMIN_SET     0x1

#define NKEEP_SET    0x2

#define NMAX_SET     0x4

#define EXPTIME_SET  0x8

typedef struct dbd_group_t dbd_group_t;

struct dbd_group_t {

    dbd_cfg_t *cfg;

    dbd_group_t *next;

    apr_pool_t *pool;

#if APR_HAS_THREADS

    apr_thread_mutex_t *mutex;

    apr_reslist_t *reslist;

    int destroyed;

#else

    ap_dbd_t *rec;

#endif

};

typedef struct {

    dbd_cfg_t *cfg;

    dbd_group_t *group;

} svr_cfg;

typedef enum { cmd_name, cmd_params, cmd_persist,

               cmd_min, cmd_keep, cmd_max, cmd_exp

} cmd_parts;

static apr_pool_t *config_pool;

static dbd_group_t *group_list;

/* a default DBDriver value that'll generate meaningful error messages */

static const char *const no_dbdriver = "[DBDriver unset]";

/* A default nmin of >0 will help with generating meaningful

 * startup error messages if the database is down.

 */

#define DEFAULT_NMIN 1

#define DEFAULT_NKEEP 2

#define DEFAULT_NMAX 10

#define DEFAULT_EXPTIME 300

#define DEFAULT_SQL_INIT_ARRAY_SIZE 5

static void *create_dbd_config(apr_pool_t *pool, server_rec *s)

{

    svr_cfg *svr = apr_pcalloc(pool, sizeof(svr_cfg));

    dbd_cfg_t *cfg = svr->cfg = apr_pcalloc(pool, sizeof(dbd_cfg_t));

    cfg->server = s;

    cfg->name = no_dbdriver; /* to generate meaningful error messages */

    cfg->params = ""; /* don't risk segfault on misconfiguration */

    cfg->persist = -1;

#if APR_HAS_THREADS

    cfg->nmin = DEFAULT_NMIN;

    cfg->nkeep = DEFAULT_NKEEP;

    cfg->nmax = DEFAULT_NMAX;

    cfg->exptime = DEFAULT_EXPTIME;

#endif

    cfg->queries = apr_hash_make(pool);

    cfg->init_queries = apr_array_make(pool, DEFAULT_SQL_INIT_ARRAY_SIZE,

                                       sizeof(const char *));

    return svr;

}

static void *merge_dbd_config(apr_pool_t *pool, void *basev, void *addv)

{

    dbd_cfg_t *base = ((svr_cfg*) basev)->cfg;

    dbd_cfg_t *add = ((svr_cfg*) addv)->cfg;

    svr_cfg *svr = apr_pcalloc(pool, sizeof(svr_cfg));

    dbd_cfg_t *new = svr->cfg = apr_pcalloc(pool, sizeof(dbd_cfg_t));

    new->server = add->server;

    new->name = (add->name != no_dbdriver) ? add->name : base->name;

    new->params = strcmp(add->params, "") ? add->params : base->params;

    new->persist = (add->persist != -1) ? add->persist : base->persist;

#if APR_HAS_THREADS

    new->nmin = (add->set&NMIN_SET) ? add->nmin : base->nmin;

    new->nkeep = (add->set&NKEEP_SET) ? add->nkeep : base->nkeep;

    new->nmax = (add->set&NMAX_SET) ? add->nmax : base->nmax;

    new->exptime = (add->set&EXPTIME_SET) ? add->exptime : base->exptime;

#endif

    new->queries = apr_hash_overlay(pool, add->queries, base->queries);

    new->init_queries = apr_array_append(pool, add->init_queries,

                                         base->init_queries);

    return svr;

}

static void ap_dbd_sql_init(server_rec *s, const char *query)

{

    svr_cfg *svr;

    const char **arr_item;

    svr = ap_get_module_config(s->module_config, &dbd_module);

    if (!svr) {

         /* some modules may call from within config directive handlers, and

          * if these are called in a server context that contains no mod_dbd

          * config directives, then we have to create our own server config

          */

         svr = create_dbd_config(config_pool, s);

         ap_set_module_config(s->module_config, &dbd_module, svr);

    }

    if (query) {

        arr_item = apr_array_push(svr->cfg->init_queries);

        *arr_item = query;

    }

}

static const char *dbd_param(cmd_parms *cmd, void *dconf, const char *val)

{

    apr_status_t rv;

    const apr_dbd_driver_t *driver = NULL;

    svr_cfg *svr = ap_get_module_config(cmd->server->module_config,

                                        &dbd_module);

    dbd_cfg_t *cfg = svr->cfg;

    switch ((long) cmd->info) {

    case cmd_name:

        cfg->name = val;

        /* loading the driver involves once-only dlloading that is

         * best done at server startup.  This also guarantees that

         * we won't return an error later.

         */

        rv = apr_dbd_get_driver(cmd->pool, cfg->name, &driver);

        if (APR_STATUS_IS_ENOTIMPL(rv)) {

            return apr_psprintf(cmd->pool, "No driver for %s", cfg->name);

        }

        else if (APR_STATUS_IS_EDSOOPEN(rv)) {

            return apr_psprintf(cmd->pool,

#ifdef NETWARE

                                "Can't load driver file dbd%s.nlm",

#else

                                "Can't load driver file apr_dbd_%s.so",

#endif

                                cfg->name);

        }

        else if (APR_STATUS_IS_ESYMNOTFOUND(rv)) {

            return apr_psprintf(cmd->pool,

                                "Failed to load driver apr_dbd_%s_driver",

                                cfg->name);

        }

        break;

    case cmd_params:

        cfg->params = val;

        break;

    }

    return NULL;

}

#if APR_HAS_THREADS

static const char *dbd_param_int(cmd_parms *cmd, void *dconf, const char *val)

{

    svr_cfg *svr = ap_get_module_config(cmd->server->module_config,

                                        &dbd_module);

    dbd_cfg_t *cfg = svr->cfg;

    const char *p;

    for (p = val; *p; ++p) {

        if (!apr_isdigit(*p)) {

            return "Argument must be numeric!";

        }

    }

    switch ((long) cmd->info) {

    case cmd_min:

        cfg->nmin = atoi(val);

        cfg->set |= NMIN_SET;

        break;

    case cmd_keep:

        cfg->nkeep = atoi(val);

        cfg->set |= NKEEP_SET;

        break;

    case cmd_max:

        cfg->nmax = atoi(val);

        cfg->set |= NMAX_SET;

        break;

    case cmd_exp:

        cfg->exptime = atoi(val);

        cfg->set |= EXPTIME_SET;

        break;

    }

    return NULL;

}

#endif

static const char *dbd_param_flag(cmd_parms *cmd, void *dconf, int flag)

{

    svr_cfg *svr = ap_get_module_config(cmd->server->module_config,

                                        &dbd_module);

    switch ((long) cmd->info) {

    case cmd_persist:

        svr->cfg->persist = flag;

        break;

    }

    return NULL;

}

static const char *dbd_prepare(cmd_parms *cmd, void *dconf, const char *query,

                               const char *label)

{

    if (!label) {

        label = query;

        query = "";

    }

    ap_dbd_prepare(cmd->server, query, label);

    return NULL;

}

static const char *dbd_init_sql(cmd_parms *cmd, void *dconf, const char *query)

{

    if (!query || *query == '\n') {

        return "You should specify SQL statement";

    }

    ap_dbd_sql_init(cmd->server, query);

    return NULL;

}

static const command_rec dbd_cmds[] = {

    AP_INIT_TAKE1("DBDriver", dbd_param, (void*)cmd_name, RSRC_CONF,

                  "SQL Driver"),

    AP_INIT_TAKE1("DBDParams", dbd_param, (void*)cmd_params, RSRC_CONF,

                  "SQL Driver Params"),

    AP_INIT_FLAG("DBDPersist", dbd_param_flag, (void*)cmd_persist, RSRC_CONF,

                 "Use persistent connection/pool"),

    AP_INIT_TAKE12("DBDPrepareSQL", dbd_prepare, NULL, RSRC_CONF,

                   "SQL statement to prepare (or nothing, to override "

                   "statement inherited from main server) and label"),

    AP_INIT_TAKE1("DBDInitSQL", dbd_init_sql, NULL, RSRC_CONF,

                   "SQL statement to be executed after connection is created"),

#if APR_HAS_THREADS

    AP_INIT_TAKE1("DBDMin", dbd_param_int, (void*)cmd_min, RSRC_CONF,

                  "Minimum number of connections"),

    /* XXX: note that mod_proxy calls this "smax" */

    AP_INIT_TAKE1("DBDKeep", dbd_param_int, (void*)cmd_keep, RSRC_CONF,

                  "Maximum number of sustained connections"),

    AP_INIT_TAKE1("DBDMax", dbd_param_int, (void*)cmd_max, RSRC_CONF,

                  "Maximum number of connections"),

    /* XXX: note that mod_proxy calls this "ttl" (time to live) */

    AP_INIT_TAKE1("DBDExptime", dbd_param_int, (void*)cmd_exp, RSRC_CONF,

                  "Keepalive time for idle connections"),

#endif

    {NULL}

};

static int dbd_pre_config(apr_pool_t *pconf, apr_pool_t *plog,

                          apr_pool_t *ptemp)

{

   config_pool = pconf;

   group_list = NULL;

   return OK;

}

DBD_DECLARE_NONSTD(void) ap_dbd_prepare(server_rec *s, const char *query,

                                        const char *label)

{

    svr_cfg *svr;

    svr = ap_get_module_config(s->module_config, &dbd_module);

    if (!svr) {

         /* some modules may call from within config directive handlers, and

          * if these are called in a server context that contains no mod_dbd

          * config directives, then we have to create our own server config

          */

         svr = create_dbd_config(config_pool, s);

         ap_set_module_config(s->module_config, &dbd_module, svr);

    }

    if (apr_hash_get(svr->cfg->queries, label, APR_HASH_KEY_STRING)

        && strcmp(query, "")) {

        ap_log_error(APLOG_MARK, APLOG_WARNING, 0, s, APLOGNO(02653)

                     "conflicting SQL statements with label %s", label);

    }

    apr_hash_set(svr->cfg->queries, label, APR_HASH_KEY_STRING, query);

}

typedef struct {

    const char *label, *query;

} dbd_query_t;

static int dbd_post_config(apr_pool_t *pconf, apr_pool_t *plog,

                           apr_pool_t *ptemp, server_rec *s)

{

    server_rec *sp;

    apr_array_header_t *add_queries = apr_array_make(ptemp, 10,

                                                     sizeof(dbd_query_t));

    for (sp = s; sp; sp = sp->next) {

        svr_cfg *svr = ap_get_module_config(sp->module_config, &dbd_module);

        dbd_cfg_t *cfg = svr->cfg;

        apr_hash_index_t *hi_first = apr_hash_first(ptemp, cfg->queries);

        dbd_group_t *group;

        /* dbd_setup in 2.2.3 and under was causing spurious error messages

         * when dbd isn't configured.  We can stop that with a quick check here

         * together with a similar check in ap_dbd_open (where being

         * unconfigured is a genuine error that must be reported).

         */

        if (cfg->name == no_dbdriver || !cfg->persist) {

            continue;

        }

        for (group = group_list; group; group = group->next) {

            dbd_cfg_t *group_cfg = group->cfg;

            apr_hash_index_t *hi;

            int group_ok = 1;

            if (strcmp(cfg->name, group_cfg->name)

                || strcmp(cfg->params, group_cfg->params)) {

                continue;

            }

#if APR_HAS_THREADS

            if (cfg->nmin != group_cfg->nmin

                || cfg->nkeep != group_cfg->nkeep

                || cfg->nmax != group_cfg->nmax

                || cfg->exptime != group_cfg->exptime) {

                continue;

            }

#endif

            add_queries->nelts = 0;

            for (hi = hi_first; hi; hi = apr_hash_next(hi)) {

                const char *label, *query;

                const char *group_query;

                apr_hash_this(hi, (void*) &label, NULL, (void*) &query);

                group_query = apr_hash_get(group_cfg->queries, label,

                                           APR_HASH_KEY_STRING);

                if (!group_query) {

                    dbd_query_t *add_query = apr_array_push(add_queries);

                    add_query->label = label;

                    add_query->query = query;

                }

                else if (strcmp(query, group_query)) {

                    group_ok = 0;

                    break;

                }

            }

            if (group_ok) {

                int i;

                for (i = 0; i < add_queries->nelts; ++i) {

                    dbd_query_t *add_query = ((dbd_query_t*) add_queries->elts)

                                             + i;

                    apr_hash_set(group_cfg->queries, add_query->label,

                                 APR_HASH_KEY_STRING, add_query->query);

                }

                svr->group = group;

                break;

            }

        }

        if (!svr->group) {

            svr->group = group = apr_pcalloc(pconf, sizeof(dbd_group_t));

            group->cfg = cfg;

            group->next = group_list;

            group_list = group;

        }

    }

    return OK;

}

static apr_status_t dbd_prepared_init(apr_pool_t *pool, dbd_cfg_t *cfg,

                                      ap_dbd_t *rec)

{

    apr_hash_index_t *hi;

    rec->prepared = apr_hash_make(pool);

    for (hi = apr_hash_first(pool, cfg->queries); hi;

         hi = apr_hash_next(hi)) {

        const char *label, *query;

        apr_dbd_prepared_t *stmt;

        apr_hash_this(hi, (void*) &label, NULL, (void*) &query);

        if (!strcmp(query, "")) {

            continue;

        }

        stmt = NULL;

        if (apr_dbd_prepare(rec->driver, pool, rec->handle, query,

                            label, &stmt)) {

            return APR_EGENERAL;

        }

        else {

            apr_hash_set(rec->prepared, label, APR_HASH_KEY_STRING, stmt);

        }

    }

    return APR_SUCCESS;

}

static apr_status_t dbd_init_sql_init(apr_pool_t *pool, dbd_cfg_t *cfg,

                                      ap_dbd_t *rec)

{

    int i;

    apr_status_t rv = APR_SUCCESS;

    for (i = 0; i < cfg->init_queries->nelts; i++) {

        int nrows;

        char **query_p;

        query_p = (char **)cfg->init_queries->elts + i;

        if (apr_dbd_query(rec->driver, rec->handle, &nrows, *query_p)) {

            rv = APR_EGENERAL;

            break;

        }

    }

    return rv;

}

static apr_status_t dbd_close(void *data)

{

    ap_dbd_t *rec = data;

    return apr_dbd_close(rec->driver, rec->handle);

}

#if APR_HAS_THREADS

static apr_status_t dbd_destruct(void *data, void *params, apr_pool_t *pool)

{

    dbd_group_t *group = params;

    if (!group->destroyed) {

        ap_dbd_t *rec = data;

        apr_pool_destroy(rec->pool);

    }

    return APR_SUCCESS;

}

#endif

/* an apr_reslist_constructor for SQL connections

 * Also use this for opening in non-reslist modes, since it gives

 * us all the error-handling in one place.

 */

static apr_status_t dbd_construct(void **data_ptr,

                                  void *params, apr_pool_t *pool)

{

    dbd_group_t *group = params;

    dbd_cfg_t *cfg = group->cfg;

    apr_pool_t *rec_pool, *prepared_pool;

    ap_dbd_t *rec;

    apr_status_t rv;

    const char *err = "";

    rv = apr_pool_create(&rec_pool, pool);

    if (rv != APR_SUCCESS) {

        ap_log_error(APLOG_MARK, APLOG_CRIT, rv, cfg->server, APLOGNO(00624)

                     "Failed to create memory pool");

        return rv;

    }

    rec = apr_pcalloc(rec_pool, sizeof(ap_dbd_t));

    rec->pool = rec_pool;

    /* The driver is loaded at config time now, so this just checks a hash.

     * If that changes, the driver DSO could be registered to unload against

     * our pool, which is probably not what we want.  Error checking isn't

     * necessary now, but in case that changes in the future ...

     */

    rv = apr_dbd_get_driver(rec->pool, cfg->name, &rec->driver);

    if (rv != APR_SUCCESS) {

        if (APR_STATUS_IS_ENOTIMPL(rv)) {

            ap_log_error(APLOG_MARK, APLOG_ERR, rv, cfg->server, APLOGNO(00625)

                         "driver for %s not available", cfg->name);

        }

        else if (APR_STATUS_IS_EDSOOPEN(rv)) {

            ap_log_error(APLOG_MARK, APLOG_ERR, rv, cfg->server, APLOGNO(00626)

                         "can't find driver for %s", cfg->name);

        }

        else if (APR_STATUS_IS_ESYMNOTFOUND(rv)) {

            ap_log_error(APLOG_MARK, APLOG_ERR, rv, cfg->server, APLOGNO(00627)

                         "driver for %s is invalid or corrupted",

                         cfg->name);

        }

        else {

            ap_log_error(APLOG_MARK, APLOG_ERR, rv, cfg->server, APLOGNO(00628)

                         "mod_dbd not compatible with APR in get_driver");

        }

        apr_pool_destroy(rec->pool);

        return rv;

    }

    rv = apr_dbd_open_ex(rec->driver, rec->pool, cfg->params, &rec->handle, &err;;

    if (rv != APR_SUCCESS) {

        switch (rv) {

        case APR_EGENERAL:

            ap_log_error(APLOG_MARK, APLOG_ERR, rv, cfg->server, APLOGNO(00629)

                         "Can't connect to %s: %s", cfg->name, err);

            break;

        default:

            ap_log_error(APLOG_MARK, APLOG_ERR, rv, cfg->server, APLOGNO(00630)

                         "mod_dbd not compatible with APR in open");

            break;

        }

        apr_pool_destroy(rec->pool);

        return rv;

    }

    apr_pool_cleanup_register(rec->pool, rec, dbd_close,

                              apr_pool_cleanup_null);

    /* we use a sub-pool for the prepared statements for each connection so

     * that they will be cleaned up first, before the connection is closed

     */

    rv = apr_pool_create(&prepared_pool, rec->pool);

    if (rv != APR_SUCCESS) {

        ap_log_error(APLOG_MARK, APLOG_CRIT, rv, cfg->server, APLOGNO(00631)

                     "Failed to create memory pool");

        apr_pool_destroy(rec->pool);

        return rv;

    }

    rv = dbd_prepared_init(prepared_pool, cfg, rec);

    if (rv != APR_SUCCESS) {

        const char *errmsg = apr_dbd_error(rec->driver, rec->handle, rv);

        ap_log_error(APLOG_MARK, APLOG_ERR, rv, cfg->server, APLOGNO(00632)

                     "failed to prepare SQL statements: %s",

                     (errmsg ? errmsg : "[???]"));

        apr_pool_destroy(rec->pool);

        return rv;

    }

    dbd_run_post_connect(prepared_pool, cfg, rec);

    *data_ptr = rec;

    return APR_SUCCESS;

}

#if APR_HAS_THREADS

static apr_status_t dbd_destroy(void *data)

{

    dbd_group_t *group = data;

    group->destroyed = 1;

    return APR_SUCCESS;

}

static apr_status_t dbd_setup(server_rec *s, dbd_group_t *group)

{

    dbd_cfg_t *cfg = group->cfg;

    apr_status_t rv;

    /* We create the reslist using a sub-pool of the pool passed to our

     * child_init hook.  No other threads can be here because we're

     * either in the child_init phase or dbd_setup_lock() acquired our mutex.

     * No other threads will use this sub-pool after this, except via

     * reslist calls, which have an internal mutex.

     *

     * We need to short-circuit the cleanup registered internally by

     * apr_reslist_create().  We do this by registering dbd_destroy()

     * as a cleanup afterwards, so that it will run before the reslist's

     * internal cleanup.

     *

     * If we didn't do this, then we could free memory twice when the pool

     * was destroyed.  When apr_pool_destroy() runs, it first destroys all

     * all the per-connection sub-pools created in dbd_construct(), and

     * then it runs the reslist's cleanup.  The cleanup calls dbd_destruct()

     * on each resource, which would then attempt to destroy the sub-pools

     * a second time.

     */

    rv = apr_reslist_create(&group->reslist,

                            cfg->nmin, cfg->nkeep, cfg->nmax,

                            apr_time_from_sec(cfg->exptime),

                            dbd_construct, dbd_destruct, group,

                            group->pool);

    if (rv != APR_SUCCESS) {

        ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(00633)

                     "failed to initialise");

        return rv;

    }

    apr_pool_cleanup_register(group->pool, group, dbd_destroy,

                              apr_pool_cleanup_null);

    return APR_SUCCESS;

}

#endif

static apr_status_t dbd_setup_init(apr_pool_t *pool, server_rec *s)

{

    dbd_group_t *group;

    apr_status_t rv = APR_SUCCESS;

    for (group = group_list; group; group = group->next) {

        apr_status_t rv2;

        rv2 = apr_pool_create(&group->pool, pool);

        if (rv2 != APR_SUCCESS) {

            ap_log_error(APLOG_MARK, APLOG_CRIT, rv2, s, APLOGNO(00634)

                         "Failed to create reslist cleanup memory pool");

            return rv2;

        }

#if APR_HAS_THREADS

        rv2 = dbd_setup(s, group);

        if (rv2 == APR_SUCCESS) {

            continue;

        }

        else if (rv == APR_SUCCESS) {

            rv = rv2;

        }

        /* we failed, so create a mutex so that subsequent competing callers

         * to ap_dbd_open can serialize themselves while they retry

         */

        rv2 = apr_thread_mutex_create(&group->mutex,

                                      APR_THREAD_MUTEX_DEFAULT, pool);

        if (rv2 != APR_SUCCESS) {

             ap_log_error(APLOG_MARK, APLOG_CRIT, rv2, s, APLOGNO(00635)

                          "Failed to create thread mutex");

             return rv2;

        }

#endif

    }

    return rv;

}

static void dbd_child_init(apr_pool_t *p, server_rec *s)

{

  apr_status_t rv = dbd_setup_init(p, s);

  if (rv) {

    ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s, APLOGNO(00636)

                 "child init failed!");

  }

}

#if APR_HAS_THREADS

static apr_status_t dbd_setup_lock(server_rec *s, dbd_group_t *group)

{

    apr_status_t rv = APR_SUCCESS, rv2;

    /* several threads could be here at the same time, all trying to

     * initialize the reslist because dbd_setup_init failed to do so

     */

    if (!group->mutex) {

        /* we already logged an error when the mutex couldn't be created */

        return APR_EGENERAL;

    }

    rv2 = apr_thread_mutex_lock(group->mutex);

    if (rv2 != APR_SUCCESS) {

        ap_log_error(APLOG_MARK, APLOG_ERR, rv2, s, APLOGNO(00637)

                     "Failed to acquire thread mutex");

        return rv2;

    }

    if (!group->reslist) {

        rv = dbd_setup(s, group);

    }

    rv2 = apr_thread_mutex_unlock(group->mutex);

    if (rv2 != APR_SUCCESS) {

        ap_log_error(APLOG_MARK, APLOG_ERR, rv2, s, APLOGNO(00638)

                     "Failed to release thread mutex");

        if (rv == APR_SUCCESS) {

            rv = rv2;

        }

    }

    return rv;

}

#endif

/* Functions we export for modules to use:

        - open acquires a connection from the pool (opens one if necessary)

        - close releases it back in to the pool

*/

DBD_DECLARE_NONSTD(void) ap_dbd_close(server_rec *s, ap_dbd_t *rec)

{

    svr_cfg *svr = ap_get_module_config(s->module_config, &dbd_module);

    if (!svr->cfg->persist) {

        apr_pool_destroy(rec->pool);

    }

#if APR_HAS_THREADS

    else {

        apr_reslist_release(svr->group->reslist, rec);

    }

#endif

}

static apr_status_t dbd_check(apr_pool_t *pool, server_rec *s, ap_dbd_t *rec)

{

    svr_cfg *svr;

    apr_status_t rv = apr_dbd_check_conn(rec->driver, pool, rec->handle);

    const char *errmsg;

    if ((rv == APR_SUCCESS) || (rv == APR_ENOTIMPL)) {

        return APR_SUCCESS;

    }

    /* we don't have a driver-specific error code, so we'll just pass

     * a "success" value and rely on the driver to ignore it

     */

    errmsg = apr_dbd_error(rec->driver, rec->handle, 0);

    if (!errmsg) {

        errmsg = "(unknown)";

    }

    svr = ap_get_module_config(s->module_config, &dbd_module);

    ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(00639)

                 "DBD [%s] Error: %s", svr->cfg->name, errmsg);

    return rv;

}

DBD_DECLARE_NONSTD(ap_dbd_t*) ap_dbd_open(apr_pool_t *pool, server_rec *s)

{

    svr_cfg *svr = ap_get_module_config(s->module_config, &dbd_module);

    dbd_group_t *group = svr->group;

    dbd_cfg_t *cfg = svr->cfg;

    ap_dbd_t *rec = NULL;

#if APR_HAS_THREADS

    apr_status_t rv;

#endif

    /* If nothing is configured, we shouldn't be here */

    if (cfg->name == no_dbdriver) {

        ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(02654)

                     "not configured");

        return NULL;

    }

    if (!cfg->persist) {

        /* Return a once-only connection */

        group = apr_pcalloc(pool, sizeof(dbd_group_t));

        group->cfg = cfg;

        dbd_construct((void*) &rec, group, pool);

        return rec;

    }

#if APR_HAS_THREADS

    if (!group->reslist) {

        if (dbd_setup_lock(s, group) != APR_SUCCESS) {

            return NULL;

        }

    }

    rv = apr_reslist_acquire(group->reslist, (void*) &rec);

    if (rv != APR_SUCCESS) {

        ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(02655)

                     "Failed to acquire DBD connection from pool!");

        return NULL;

    }

    if (dbd_check(pool, s, rec) != APR_SUCCESS) {

        apr_reslist_invalidate(group->reslist, rec);

        return NULL;

    }

#else

    /* If we have a persistent connection and it's good, we'll use it;

     * since this is non-threaded, we can update without a mutex

     */

    rec = group->rec;

    if (rec) {

        if (dbd_check(pool, s, rec) != APR_SUCCESS) {

            apr_pool_destroy(rec->pool);

            rec = NULL;

        }

    }

    /* We don't have a connection right now, so we'll open one */

    if (!rec) {

        dbd_construct((void*) &rec, group, group->pool);

        group->rec = rec;

    }

#endif

    return rec;

}

#if APR_HAS_THREADS

typedef struct {

    ap_dbd_t *rec;

    apr_reslist_t *reslist;

} dbd_acquire_t;

static apr_status_t dbd_release(void *data)

{

    dbd_acquire_t *acq = data;

    apr_reslist_release(acq->reslist, acq->rec);

    return APR_SUCCESS;

}

DBD_DECLARE_NONSTD(ap_dbd_t *) ap_dbd_acquire(request_rec *r)

{

    dbd_acquire_t *acq;

    while (!ap_is_initial_req(r)) {

        if (r->prev) {

            r = r->prev;

        }

        else if (r->main) {

            r = r->main;

        }