res_config_sqlite.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2006, Proformatique
 *
 * Written by Richard Braun <[email protected]>
 *
 * Based on res_sqlite3 by Anthony Minessale II,
 * and res_config_mysql by Matthew Boehm
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*!
 * \page res_config_sqlite
 *
 * \section intro_sec Presentation
 *
 * res_config_sqlite is a module for the Asterisk Open Source PBX to
 * support SQLite 2 databases. It can be used to fetch configuration
 * from a database (static configuration files and/or using the Asterisk
 * RealTime Architecture - ARA).  It can also be used to log CDR entries.
 * Note that Asterisk already comes with a module named cdr_sqlite.
 * There are two reasons for including it in res_config_sqlite:
 * the first is that rewriting it was a training to learn how to write a
 * simple module for Asterisk, the other is to have the same database open for
 * all kinds of operations, which improves reliability and performance.
 *
 * \section conf_sec Configuration
 *
 * The main configuration file is res_config_sqlite.conf.sample It must be readable or
 * res_config_sqlite will fail to start. It is suggested to use the sample file
 * in this package as a starting point. The file has only one section
 * named <code>general</code>. Here are the supported parameters :
 *
 * <dl>
 * <dt><code>dbfile</code></dt>
 * <dd>The absolute path to the SQLite database (the file can be non existent,
 *       res_config_sqlite will create it if it has the appropriate rights)</dd>
 * <dt><code>config_table</code></dt>
 * <dd>The table used for static configuration</dd>
 * <dt><code>cdr_table</code></dt>
 * <dd>The table used to store CDR entries (if ommitted, CDR support is
 *       disabled)</dd>
 * </dl>
 *
 * To use res_config_sqlite for static and/or RealTime configuration, refer to the
 * Asterisk documentation. The file tables.sql can be used to create the
 * needed tables.
 *
 * \section status_sec Driver status
 *
 * The CLI command <code>show sqlite status</code> returns status information
 * about the running driver.
 *
 * \section credits_sec Credits
 *
 * res_config_sqlite was developed by Richard Braun at the Proformatique company.
 */

/*!
 * \file
 * \brief res_config_sqlite module.
 */

/*! \li \ref res_config_sqlite.c uses the configuration file \ref res_config_sqlite.conf
 * \addtogroup configuration_file Configuration Files
 */

/*!
 * \page res_config_sqlite.conf res_config_sqlite.conf
 * \verbinclude res_config_sqlite.conf.sample
 */

/*** MODULEINFO
   <depend>sqlite</depend>
   <support_level>deprecated</support_level>
 ***/

#include "asterisk.h"

#include <sqlite.h>

#include "asterisk/logger.h"
#include "asterisk/app.h"
#include "asterisk/pbx.h"
#include "asterisk/cdr.h"
#include "asterisk/cli.h"
#include "asterisk/lock.h"
#include "asterisk/config.h"
#include "asterisk/module.h"
#include "asterisk/linkedlists.h"

#define MACRO_BEGIN  do {
#define MACRO_END } while (0)

#define RES_CONFIG_SQLITE_NAME "res_config_sqlite"
#define RES_CONFIG_SQLITE_DRIVER "sqlite"
#define RES_CONFIG_SQLITE_DESCRIPTION "Resource Module for SQLite 2"
#define RES_CONFIG_SQLITE_CONF_FILE "res_config_sqlite.conf"

enum {
   RES_CONFIG_SQLITE_CONFIG_ID,
   RES_CONFIG_SQLITE_CONFIG_CAT_METRIC,
   RES_CONFIG_SQLITE_CONFIG_VAR_METRIC,
   RES_CONFIG_SQLITE_CONFIG_COMMENTED,
   RES_CONFIG_SQLITE_CONFIG_FILENAME,
   RES_CONFIG_SQLITE_CONFIG_CATEGORY,
   RES_CONFIG_SQLITE_CONFIG_VAR_NAME,
   RES_CONFIG_SQLITE_CONFIG_VAR_VAL,
   RES_CONFIG_SQLITE_CONFIG_COLUMNS,
};

#define SET_VAR(config, to, from)         \
MACRO_BEGIN                \
   int __error;               \
                     \
   __error = set_var(&to, #to, from->value); \
                     \
   if (__error) {             \
      ast_config_destroy(config);      \
      unload_config();        \
      return 1;            \
   }                 \
MACRO_END

AST_THREADSTORAGE(sql_buf);
AST_THREADSTORAGE(where_buf);

/*!
 * Maximum number of loops before giving up executing a query. Calls to
 * sqlite_xxx() functions which can return SQLITE_BUSY
 * are enclosed by RES_CONFIG_SQLITE_BEGIN and RES_CONFIG_SQLITE_END, e.g.
 * <pre>
 * char *errormsg;
 * int error;
 *
 * RES_CONFIG_SQLITE_BEGIN
 *  error = sqlite_exec(db, query, NULL, NULL, &errormsg);
 * RES_CONFIG_SQLITE_END(error)
 *
 * if (error)
 *  ...;
 * </pre>
 */
#define RES_CONFIG_SQLITE_MAX_LOOPS 10

/*!
 * Macro used before executing a query.
 *
 * \see RES_CONFIG_SQLITE_MAX_LOOPS.
 */
#define RES_CONFIG_SQLITE_BEGIN                 \
MACRO_BEGIN                      \
   int __i;                   \
                           \
   for (__i = 0; __i < RES_CONFIG_SQLITE_MAX_LOOPS; __i++)  {

/*!
 * Macro used after executing a query.
 *
 * \see RES_CONFIG_SQLITE_MAX_LOOPS.
 */
#define RES_CONFIG_SQLITE_END(error)               \
      if (error != SQLITE_BUSY)  \
         break;                  \
      usleep(1000);                 \
   }                       \
MACRO_END;

/*!
 * Structure sent to the SQLite callback function for static configuration.
 *
 * \see add_cfg_entry()
 */
struct cfg_entry_args {
   struct ast_config *cfg;
   struct ast_category *cat;
   char *cat_name;
   struct ast_flags flags;
   const char *who_asked;
};

/*!
 * Structure sent to the SQLite callback function for RealTime configuration.
 *
 * \see add_rt_cfg_entry()
 */
struct rt_cfg_entry_args {
   struct ast_variable *var;
   struct ast_variable *last;
};

/*!
 * Structure sent to the SQLite callback function for RealTime configuration
 * (realtime_multi_handler()).
 *
 * \see add_rt_multi_cfg_entry()
 */
struct rt_multi_cfg_entry_args {
   struct ast_config *cfg;
   char *initfield;
};

/*!
 * \brief Allocate a variable.
 * \param var the address of the variable to set (it will be allocated)
 * \param name the name of the variable (for error handling)
 * \param value the value to store in var
 * \retval 0 on success
 * \retval 1 if an allocation error occurred
 */
static int set_var(char **var, const char *name, const char *value);

/*!
 * \brief Load the configuration file.
 * \see unload_config()
 *
 * This function sets dbfile, config_table, and cdr_table. It calls
 * check_vars() before returning, and unload_config() if an error occurred.
 *
 * \retval 0 on success
 * \retval 1 if an error occurred
 */
static int load_config(void);

/*!
 * \brief Free resources related to configuration.
 * \see load_config()
 */
static void unload_config(void);

/*!
 * \brief Asterisk callback function for CDR support.
 * \param cdr the CDR entry Asterisk sends us.
 *
 * Asterisk will call this function each time a CDR entry must be logged if
 * CDR support is enabled.
 *
 * \retval 0 on success
 * \retval 1 if an error occurred
 */
static int cdr_handler(struct ast_cdr *cdr);

/*!
 * \brief SQLite callback function for static configuration.
 *
 * This function is passed to the SQLite engine as a callback function to
 * parse a row and store it in a struct ast_config object. It relies on
 * resulting rows being sorted by category.
 *
 * \param arg a pointer to a struct cfg_entry_args object
 * \param argc number of columns
 * \param argv values in the row
 * \param columnNames names and types of the columns
 * \retval 0 on success
 * \retval 1 if an error occurred
 * \see cfg_entry_args
 * \see sql_get_config_table
 * \see config_handler()
 */
static int add_cfg_entry(void *arg, int argc, char **argv, char **columnNames);

/*!
 * \brief Asterisk callback function for static configuration.
 *
 * Asterisk will call this function when it loads its static configuration,
 * which usually happens at startup and reload.
 *
 * \param database the database to use (ignored)
 * \param table the table to use
 * \param file the file to load from the database
 * \param cfg the struct ast_config object to use when storing variables
 * \param flags Optional flags.  Not used.
 * \param suggested_incl suggest include.
 * \param who_asked
 * \retval cfg object
 * \retval NULL if an error occurred
 * \see add_cfg_entry()
 */
static struct ast_config * config_handler(const char *database, const char *table, const char *file,
   struct ast_config *cfg, struct ast_flags flags, const char *suggested_incl, const char *who_asked);

/*!
 * \brief SQLite callback function for RealTime configuration.
 *
 * This function is passed to the SQLite engine as a callback function to
 * parse a row and store it in a linked list of struct ast_variable objects.
 *
 * \param arg a pointer to a struct rt_cfg_entry_args object
 * \param argc number of columns
 * \param argv values in the row
 * \param columnNames names and types of the columns
 * \retval 0 on success.
 * \retval 1 if an error occurred.
 * \see rt_cfg_entry_args
 * \see realtime_handler()
 */
static int add_rt_cfg_entry(void *arg, int argc, char **argv,
   char **columnNames);

/*!
 * \brief Asterisk callback function for RealTime configuration.
 *
 * Asterisk will call this function each time it requires a variable
 * through the RealTime architecture. ap is a list of parameters and
 * values used to find a specific row, e.g one parameter "name" and
 * one value "123" so that the SQL query becomes <code>SELECT * FROM
 * table WHERE name = '123';</code>.
 *
 * \param database the database to use (ignored)
 * \param table the table to use
 * \param fields list of parameters and values to match
 *
 * \retval a linked list of struct ast_variable objects
 * \retval NULL if an error occurred
 * \see add_rt_cfg_entry()
 */
static struct ast_variable * realtime_handler(const char *database,
   const char *table, const struct ast_variable *fields);

/*!
 * \brief SQLite callback function for RealTime configuration.
 *
 * This function performs the same actions as add_rt_cfg_entry() except
 * that the rt_multi_cfg_entry_args structure is designed to store
 * categories in addition to variables.
 *
 * \param arg a pointer to a struct rt_multi_cfg_entry_args object
 * \param argc number of columns
 * \param argv values in the row
 * \param columnNames names and types of the columns
 * \retval 0 on success.
 * \retval 1 if an error occurred.
 * \see rt_multi_cfg_entry_args
 * \see realtime_multi_handler()
 */
static int add_rt_multi_cfg_entry(void *arg, int argc, char **argv,
   char **columnNames);

/*!
 * \brief Asterisk callback function for RealTime configuration.
 *
 * This function performs the same actions as realtime_handler() except
 * that it can store variables per category, and can return several
 * categories.
 *
 * \param database the database to use (ignored)
 * \param table the table to use
 * \param fields list of parameters and values to match
 * \retval a struct ast_config object storing categories and variables.
 * \retval NULL if an error occurred.
 *
 * \see add_rt_multi_cfg_entry()
 */
static struct ast_config * realtime_multi_handler(const char *database,
   const char *table, const struct ast_variable *fields);

/*!
 * \brief Asterisk callback function for RealTime configuration (variable
 * update).
 *
 * Asterisk will call this function each time a variable has been modified
 * internally and must be updated in the backend engine. keyfield and entity
 * are used to find the row to update, e.g. <code>UPDATE table SET ... WHERE
 * keyfield = 'entity';</code>. ap is a list of parameters and values with the
 * same format as the other realtime functions.
 *
 * \param database the database to use (ignored)
 * \param table the table to use
 * \param keyfield the column of the matching cell
 * \param entity the value of the matching cell
 * \param fields list of parameters and new values to update in the database
 * \retval the number of affected rows.
 * \retval -1 if an error occurred.
 */
static int realtime_update_handler(const char *database, const char *table,
   const char *keyfield, const char *entity, const struct ast_variable *fields);
static int realtime_update2_handler(const char *database, const char *table,
   const struct ast_variable *lookup_fields, const struct ast_variable *update_fields);

/*!
 * \brief Asterisk callback function for RealTime configuration (variable
 * create/store).
 *
 * Asterisk will call this function each time a variable has been created
 * internally and must be stored in the backend engine.
 * are used to find the row to update, e.g. ap is a list of parameters and
 * values with the same format as the other realtime functions.
 *
 * \param database the database to use (ignored)
 * \param table the table to use
 * \param fields list of parameters and new values to insert into the database
 * \retval the rowid of inserted row.
 * \retval -1 if an error occurred.
 */
static int realtime_store_handler(const char *database, const char *table,
   const struct ast_variable *fields);

/*!
 * \brief Asterisk callback function for RealTime configuration (destroys
 * variable).
 *
 * Asterisk will call this function each time a variable has been destroyed
 * internally and must be removed from the backend engine. keyfield and entity
 * are used to find the row to delete, e.g. <code>DELETE FROM table WHERE
 * keyfield = 'entity';</code>. ap is a list of parameters and values with the
 * same format as the other realtime functions.
 *
 * \param database the database to use (ignored)
 * \param table the table to use
 * \param keyfield the column of the matching cell
 * \param entity the value of the matching cell
 * \param fields list of additional parameters for cell matching
 * \retval the number of affected rows.
 * \retval -1 if an error occurred.
 */
static int realtime_destroy_handler(const char *database, const char *table,
   const char *keyfield, const char *entity, const struct ast_variable *fields);

/*!
 * \brief Asterisk callback function for the CLI status command.
 *
 * \param e CLI command
 * \param cmd
 * \param a CLI argument list
 * \return RESULT_SUCCESS
 */
static char *handle_cli_show_sqlite_status(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);
static char *handle_cli_sqlite_show_tables(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a);

static int realtime_require_handler(const char *database, const char *table, va_list ap);
static int realtime_unload_handler(const char *unused, const char *tablename);

/*! The SQLite database object. */
static sqlite *db;

/*! Set to 1 if CDR support is enabled. */
static int use_cdr;

/*! Set to 1 if the CDR callback function was registered. */
static int cdr_registered;

/*! Set to 1 if the CLI status command callback function was registered. */
static int cli_status_registered;

/*! The path of the database file. */
static char *dbfile;

/*! The name of the static configuration table. */
static char *config_table;

/*! The name of the table used to store CDR entries. */
static char *cdr_table;

/*!
 * The structure specifying all callback functions used by Asterisk for static
 * and RealTime configuration.
 */
static struct ast_config_engine sqlite_engine =
{
   .name = RES_CONFIG_SQLITE_DRIVER,
   .load_func = config_handler,
   .realtime_func = realtime_handler,
   .realtime_multi_func = realtime_multi_handler,
   .store_func = realtime_store_handler,
   .destroy_func = realtime_destroy_handler,
   .update_func = realtime_update_handler,
   .update2_func = realtime_update2_handler,
   .require_func = realtime_require_handler,
   .unload_func = realtime_unload_handler,
};

/*!
 * The mutex used to prevent simultaneous access to the SQLite database.
 */
AST_MUTEX_DEFINE_STATIC(mutex);

/*!
 * Structure containing details and callback functions for the CLI status
 * command.
 */
static struct ast_cli_entry cli_status[] = {
   AST_CLI_DEFINE(handle_cli_show_sqlite_status, "Show status information about the SQLite 2 driver"),
   AST_CLI_DEFINE(handle_cli_sqlite_show_tables, "Cached table information about the SQLite 2 driver"),
};

struct sqlite_cache_columns {
   char *name;
   char *type;
   unsigned char isint;    /*!< By definition, only INTEGER PRIMARY KEY is an integer; everything else is a string. */
   AST_RWLIST_ENTRY(sqlite_cache_columns) list;
};

struct sqlite_cache_tables {
   char *name;
   AST_RWLIST_HEAD(_columns, sqlite_cache_columns) columns;
   AST_RWLIST_ENTRY(sqlite_cache_tables) list;
};

static AST_RWLIST_HEAD_STATIC(sqlite_tables, sqlite_cache_tables);

/*
 * Taken from Asterisk 1.2 cdr_sqlite.so.
 */

/*! SQL query format to create the CDR table if non existent. */
static char *sql_create_cdr_table =
"CREATE TABLE '%q' (\n"
"  id    INTEGER,\n"
"  clid     VARCHAR(80) NOT NULL DEFAULT '',\n"
"  src      VARCHAR(80) NOT NULL DEFAULT '',\n"
"  dst      VARCHAR(80) NOT NULL DEFAULT '',\n"
"  dcontext VARCHAR(80) NOT NULL DEFAULT '',\n"
"  channel     VARCHAR(80) NOT NULL DEFAULT '',\n"
"  dstchannel  VARCHAR(80) NOT NULL DEFAULT '',\n"
"  lastapp     VARCHAR(80) NOT NULL DEFAULT '',\n"
"  lastdata VARCHAR(80) NOT NULL DEFAULT '',\n"
"  start    DATETIME NOT NULL DEFAULT '0000-00-00 00:00:00',\n"
"  answer      DATETIME NOT NULL DEFAULT '0000-00-00 00:00:00',\n"
"  end      DATETIME NOT NULL DEFAULT '0000-00-00 00:00:00',\n"
"  duration INT(11)     NOT NULL DEFAULT 0,\n"
"  billsec     INT(11)     NOT NULL DEFAULT 0,\n"
"  disposition VARCHAR(45) NOT NULL DEFAULT '',\n"
"  amaflags INT(11)     NOT NULL DEFAULT 0,\n"
"  accountcode VARCHAR(20) NOT NULL DEFAULT '',\n"
"  uniqueid VARCHAR(32) NOT NULL DEFAULT '',\n"
"  userfield   VARCHAR(255)   NOT NULL DEFAULT '',\n"
"  PRIMARY KEY (id)\n"
");";

/*!
 * SQL query format to describe the table structure
 */
#define sql_table_structure "SELECT sql FROM sqlite_master WHERE type='table' AND tbl_name='%s'"

/*!
 * SQL query format to fetch the static configuration of a file.
 * Rows must be sorted by category.
 *
 * \see add_cfg_entry()
 */
#define sql_get_config_table \
   "SELECT *" \
   "  FROM '%q'" \
   "  WHERE filename = '%q' AND commented = 0" \
   "  ORDER BY cat_metric ASC, var_metric ASC;"

static void free_table(struct sqlite_cache_tables *tblptr)
{
   struct sqlite_cache_columns *col;

   /* Obtain a write lock to ensure there are no read locks outstanding */
   AST_RWLIST_WRLOCK(&(tblptr->columns));
   while ((col = AST_RWLIST_REMOVE_HEAD(&(tblptr->columns), list))) {
      ast_free(col);
   }
   AST_RWLIST_UNLOCK(&(tblptr->columns));
   AST_RWLIST_HEAD_DESTROY(&(tblptr->columns));
   ast_free(tblptr);
}

static int find_table_cb(void *vtblptr, int argc, char **argv, char **columnNames)
{
   struct sqlite_cache_tables *tblptr = vtblptr;
   char *sql = ast_strdupa(argv[0]), *start, *end, *type, *remainder;
   int i;
   AST_DECLARE_APP_ARGS(fie,
      AST_APP_ARG(ld)[100]; /* This means we support up to 100 columns per table */
   );
   struct sqlite_cache_columns *col;

   /* This is really fun.  We get to parse an SQL statement to figure out
    * what columns are in the table.
    */
   if ((start = strchr(sql, '(')) && (end = strrchr(sql, ')'))) {
      start++;
      *end = '\0';
   } else {
      /* Abort */
      return -1;
   }

   AST_STANDARD_APP_ARGS(fie, start);
   for (i = 0; i < fie.argc; i++) {
      fie.ld[i] = ast_skip_blanks(fie.ld[i]);
      ast_debug(5, "Found field: %s\n", fie.ld[i]);
      if (strncasecmp(fie.ld[i], "PRIMARY KEY", 11) == 0 && (start = strchr(fie.ld[i], '(')) && (end = strchr(fie.ld[i], ')'))) {
         *end = '\0';
         AST_RWLIST_TRAVERSE(&(tblptr->columns), col, list) {
            if (strcasecmp(start + 1, col->name) == 0 && strcasestr(col->type, "INTEGER")) {
               col->isint = 1;
            }
         }
         continue;
      }
      /* type delimiter could be any space character */
      for (type = fie.ld[i]; *type > 32; type++);
      *type++ = '\0';
      type = ast_skip_blanks(type);
      for (remainder = type; *remainder > 32; remainder++);
      *remainder = '\0';
      if (!(col = ast_calloc(1, sizeof(*col) + strlen(fie.ld[i]) + strlen(type) + 2))) {
         return -1;
      }
      col->name = (char *)col + sizeof(*col);
      col->type = (char *)col + sizeof(*col) + strlen(fie.ld[i]) + 1;
      strcpy(col->name, fie.ld[i]); /* SAFE */
      strcpy(col->type, type); /* SAFE */
      if (strcasestr(col->type, "INTEGER") && strcasestr(col->type, "PRIMARY KEY")) {
         col->isint = 1;
      }
      AST_LIST_INSERT_TAIL(&(tblptr->columns), col, list);
   }
   return 0;
}

static struct sqlite_cache_tables *find_table(const char *tablename)
{
   struct sqlite_cache_tables *tblptr;
   int i, err;
   char *sql, *errstr = NULL;

   AST_RWLIST_RDLOCK(&sqlite_tables);

   for (i = 0; i < 2; i++) {
      AST_RWLIST_TRAVERSE(&sqlite_tables, tblptr, list) {
         if (strcmp(tblptr->name, tablename) == 0) {
            break;
         }
      }
      if (tblptr) {
         AST_RWLIST_RDLOCK(&(tblptr->columns));
         AST_RWLIST_UNLOCK(&sqlite_tables);
         return tblptr;
      }

      if (i == 0) {
         AST_RWLIST_UNLOCK(&sqlite_tables);
         AST_RWLIST_WRLOCK(&sqlite_tables);
      }
   }

   /* Table structure not cached; build the structure now */
   if (ast_asprintf(&sql, sql_table_structure, tablename) < 0) {
      sql = NULL;
   }
   if (!(tblptr = ast_calloc(1, sizeof(*tblptr) + strlen(tablename) + 1))) {
      AST_RWLIST_UNLOCK(&sqlite_tables);
      ast_log(LOG_ERROR, "Memory error.  Cannot cache table '%s'\n", tablename);
      ast_free(sql);
      return NULL;
   }
   tblptr->name = (char *)tblptr + sizeof(*tblptr);
   strcpy(tblptr->name, tablename); /* SAFE */
   AST_RWLIST_HEAD_INIT(&(tblptr->columns));

   ast_debug(1, "About to query table structure: %s\n", sql);

   ast_mutex_lock(&mutex);
   if ((err = sqlite_exec(db, sql, find_table_cb, tblptr, &errstr))) {
      ast_mutex_unlock(&mutex);
      ast_log(LOG_WARNING, "SQLite error %d: %s\n", err, errstr);
      ast_free(errstr);
      free_table(tblptr);
      AST_RWLIST_UNLOCK(&sqlite_tables);
      ast_free(sql);
      return NULL;
   }
   ast_mutex_unlock(&mutex);
   ast_free(sql);

   if (AST_LIST_EMPTY(&(tblptr->columns))) {
      free_table(tblptr);
      AST_RWLIST_UNLOCK(&sqlite_tables);
      return NULL;
   }

   AST_RWLIST_INSERT_TAIL(&sqlite_tables, tblptr, list);
   AST_RWLIST_RDLOCK(&(tblptr->columns));
   AST_RWLIST_UNLOCK(&sqlite_tables);
   return tblptr;
}

#define release_table(a)   AST_RWLIST_UNLOCK(&((a)->columns))

static int set_var(char **var, const char *name, const char *value)
{
   if (*var)
      ast_free(*var);

   *var = ast_strdup(value);

   if (!*var) {
      ast_log(LOG_WARNING, "Unable to allocate variable %s\n", name);
      return 1;
   }

   return 0;
}

static int check_vars(void)
{
   if (!dbfile) {
      ast_log(LOG_ERROR, "Required parameter undefined: dbfile\n");
      return 1;
   }

   use_cdr = (cdr_table != NULL);

   return 0;
}

static int load_config(void)
{
   struct ast_config *config;
   struct ast_variable *var;
   int error;
   struct ast_flags config_flags = { 0 };

   config = ast_config_load(RES_CONFIG_SQLITE_CONF_FILE, config_flags);

   if (config == CONFIG_STATUS_FILEMISSING || config == CONFIG_STATUS_FILEINVALID) {
      ast_log(LOG_ERROR, "Unable to load " RES_CONFIG_SQLITE_CONF_FILE "\n");
      return 1;
   }

   for (var = ast_variable_browse(config, "general"); var; var = var->next) {
      if (!strcasecmp(var->name, "dbfile"))
         SET_VAR(config, dbfile, var);
      else if (!strcasecmp(var->name, "config_table"))
         SET_VAR(config, config_table, var);
      else if (!strcasecmp(var->name, "cdr_table")) {
         SET_VAR(config, cdr_table, var);
      } else
         ast_log(LOG_WARNING, "Unknown parameter : %s\n", var->name);
   }

   ast_config_destroy(config);
   error = check_vars();

   if (error) {
      unload_config();
      return 1;
   }

   return 0;
}

static void unload_config(void)
{
   struct sqlite_cache_tables *tbl;
   ast_free(dbfile);
   dbfile = NULL;
   ast_free(config_table);
   config_table = NULL;
   ast_free(cdr_table);
   cdr_table = NULL;
   AST_RWLIST_WRLOCK(&sqlite_tables);
   while ((tbl = AST_RWLIST_REMOVE_HEAD(&sqlite_tables, list))) {
      free_table(tbl);
   }
   AST_RWLIST_UNLOCK(&sqlite_tables);
}

static int cdr_handler(struct ast_cdr *cdr)
{
   char *errormsg = NULL, *tmp, workspace[500];
   int error, scannum;
   struct sqlite_cache_tables *tbl = find_table(cdr_table);
   struct sqlite_cache_columns *col;
   struct ast_str *sql1 = ast_str_create(160), *sql2 = ast_str_create(16);
   int first = 1;

   if (!sql1 || !sql2) {
      ast_free(sql1);
      ast_free(sql2);
      return -1;
   }

   if (!tbl) {
      ast_log(LOG_WARNING, "No such table: %s\n", cdr_table);
      ast_free(sql1);
      ast_free(sql2);
      return -1;
   }

   ast_str_set(&sql1, 0, "INSERT INTO %s (", cdr_table);
   ast_str_set(&sql2, 0, ") VALUES (");

   AST_RWLIST_TRAVERSE(&(tbl->columns), col, list) {
      if (col->isint) {
         ast_cdr_format_var(cdr, col->name, &tmp, workspace, sizeof(workspace), 1);
         if (!tmp) {
            continue;
         }
         if (sscanf(tmp, "%30d", &scannum) == 1) {
            ast_str_append(&sql1, 0, "%s%s", first ? "" : ",", col->name);
            ast_str_append(&sql2, 0, "%s%d", first ? "" : ",", scannum);
         }
      } else {
         ast_cdr_format_var(cdr, col->name, &tmp, workspace, sizeof(workspace), 0);
         if (!tmp) {
            continue;
         }
         ast_str_append(&sql1, 0, "%s%s", first ? "" : ",", col->name);
         tmp = sqlite_mprintf("%Q", tmp);
         ast_str_append(&sql2, 0, "%s%s", first ? "" : ",", tmp);
         sqlite_freemem(tmp);
      }
      first = 0;
   }
   release_table(tbl);

   ast_str_append(&sql1, 0, "%s)", ast_str_buffer(sql2));
   ast_free(sql2);

   ast_debug(1, "SQL query: %s\n", ast_str_buffer(sql1));

   ast_mutex_lock(&mutex);

   RES_CONFIG_SQLITE_BEGIN
      error = sqlite_exec(db, ast_str_buffer(sql1), NULL, NULL, &errormsg);
   RES_CONFIG_SQLITE_END(error)

   ast_mutex_unlock(&mutex);

   ast_free(sql1);

   if (error) {
      ast_log(LOG_ERROR, "%s\n", S_OR(errormsg, sqlite_error_string(error)));
      sqlite_freemem(errormsg);
      return 1;
   }
   sqlite_freemem(errormsg);

   return 0;
}

static int add_cfg_entry(void *arg, int argc, char **argv, char **columnNames)
{
   struct cfg_entry_args *args;
   struct ast_variable *var;

   if (argc != RES_CONFIG_SQLITE_CONFIG_COLUMNS) {
      ast_log(LOG_WARNING, "Corrupt table\n");
      return 1;
   }

   args = arg;

   if (!strcmp(argv[RES_CONFIG_SQLITE_CONFIG_VAR_NAME], "#include")) {
      struct ast_config *cfg;
      char *val;

      val = argv[RES_CONFIG_SQLITE_CONFIG_VAR_VAL];
      cfg = ast_config_internal_load(val, args->cfg, args->flags, "", args->who_asked);

      if (!cfg) {
         ast_log(LOG_WARNING, "Unable to include %s\n", val);
         return 1;
      } else {
         args->cfg = cfg;
         return 0;
      }
   }

   if (!args->cat_name || strcmp(args->cat_name, argv[RES_CONFIG_SQLITE_CONFIG_CATEGORY])) {
      args->cat = ast_category_new_dynamic(argv[RES_CONFIG_SQLITE_CONFIG_CATEGORY]);
      if (!args->cat) {
         return 1;
      }

      ast_free(args->cat_name);
      args->cat_name = ast_strdup(argv[RES_CONFIG_SQLITE_CONFIG_CATEGORY]);

      if (!args->cat_name) {
         ast_category_destroy(args->cat);
         return 1;
      }

      ast_category_append(args->cfg, args->cat);
   }

   var = ast_variable_new(argv[RES_CONFIG_SQLITE_CONFIG_VAR_NAME], argv[RES_CONFIG_SQLITE_CONFIG_VAR_VAL], "");

   if (!var) {
      ast_log(LOG_WARNING, "Unable to allocate variable\n");
      return 1;
   }

   ast_variable_append(args->cat, var);

   return 0;
}

static struct ast_config *config_handler(const char *database, const char *table, const char *file,
   struct ast_config *cfg, struct ast_flags flags, const char *suggested_incl, const char *who_asked)
{
   struct cfg_entry_args args;
   char *query, *errormsg = NULL;
   int error;

   if (!config_table) {
      if (!table) {
         ast_log(LOG_ERROR, "Table name unspecified\n");
         return NULL;
      }
   } else
      table = config_table;

   query = sqlite_mprintf(sql_get_config_table, table, file);

   if (!query) {
      ast_log(LOG_WARNING, "Unable to allocate SQL query\n");
      return NULL;
   }

   ast_debug(1, "SQL query: %s\n", query);
   args.cfg = cfg;
   args.cat = NULL;
   args.cat_name = NULL;
   args.flags = flags;
   args.who_asked = who_asked;

   ast_mutex_lock(&mutex);

   RES_CONFIG_SQLITE_BEGIN
      error = sqlite_exec(db, query, add_cfg_entry, &args, &errormsg);
   RES_CONFIG_SQLITE_END(error)

   ast_mutex_unlock(&mutex);

   ast_free(args.cat_name);
   sqlite_freemem(query);

   if (error) {
      ast_log(LOG_ERROR, "%s\n", S_OR(errormsg, sqlite_error_string(error)));
      sqlite_freemem(errormsg);
      return NULL;
   }
   sqlite_freemem(errormsg);

   return cfg;
}

static int add_rt_cfg_entry(void *arg, int argc, char **argv, char **columnNames)
{
   struct rt_cfg_entry_args *args;
   struct ast_variable *var;
   int i;

   args = arg;

   for (i = 0; i < argc; i++) {
      if (!argv[i])
         continue;

      if (!(var = ast_variable_new(columnNames[i], argv[i], "")))
         return 1;

      if (!args->var)
         args->var = var;

      if (!args->last)
         args->last = var;
      else {
         args->last->next = var;
         args->last = var;
      }
   }

   return 0;
}

static struct ast_variable * realtime_handler(const char *database, const char *table, const struct ast_variable *fields)
{
   char *query, *errormsg = NULL, *op, *tmp_str;
   struct rt_cfg_entry_args args;
   const struct ast_variable *field = fields;
   int error;

   if (!table) {
      ast_log(LOG_WARNING, "Table name unspecified\n");
      return NULL;
   }

   if (!fields) {
      return NULL;
   }

   op = (strchr(field->name, ' ') == NULL) ? " =" : "";

/* \cond DOXYGEN_CAN_PARSE_THIS */
#undef QUERY
#define QUERY "SELECT * FROM '%q' WHERE%s %q%s '%q'"
/* \endcond */

   query = sqlite_mprintf(QUERY, table, (config_table && !strcmp(config_table, table)) ? " commented = 0 AND" : "", field->name, op, field->value);

   if (!query) {
      ast_log(LOG_WARNING, "Unable to allocate SQL query\n");
      return NULL;
   }

   while ((field = field->next)) {
      op = (strchr(field->name, ' ') == NULL) ? " =" : "";
      tmp_str = sqlite_mprintf("%s AND %q%s '%q'", query, field->name, op, field->value);
      sqlite_freemem(query);

      if (!tmp_str) {
         ast_log(LOG_WARNING, "Unable to reallocate SQL query\n");
         return NULL;
      }

      query = tmp_str;
   }

   tmp_str = sqlite_mprintf("%s LIMIT 1;", query);
   sqlite_freemem(query);

   if (!tmp_str) {
      ast_log(LOG_WARNING, "Unable to reallocate SQL query\n");
      return NULL;
   }

   query = tmp_str;
   ast_debug(1, "SQL query: %s\n", query);
   args.var = NULL;
   args.last = NULL;

   ast_mutex_lock(&mutex);

   RES_CONFIG_SQLITE_BEGIN
      error = sqlite_exec(db, query, add_rt_cfg_entry, &args, &errormsg);
   RES_CONFIG_SQLITE_END(error)

   ast_mutex_unlock(&mutex);

   sqlite_freemem(query);

   if (error) {
      ast_log(LOG_WARNING, "%s\n", S_OR(errormsg, sqlite_error_string(error)));
      sqlite_freemem(errormsg);
      ast_variables_destroy(args.var);
      return NULL;
   }
   sqlite_freemem(errormsg);

   return args.var;
}

static int add_rt_multi_cfg_entry(void *arg, int argc, char **argv, char **columnNames)
{
   struct rt_multi_cfg_entry_args *args;
   struct ast_category *cat;
   struct ast_variable *var;
   char *cat_name;
   size_t i;

   args = arg;
   cat_name = NULL;

   /*
    * cat_name should always be set here, since initfield is forged from
    * params[0] in realtime_multi_handler(), which is a search parameter
    * of the SQL query.
    */
   for (i = 0; i < argc; i++) {
      if (!strcmp(args->initfield, columnNames[i]))
         cat_name = argv[i];
   }

   if (!cat_name) {
      ast_log(LOG_ERROR, "Bogus SQL results, cat_name is NULL !\n");
      return 1;
   }

   cat = ast_category_new_dynamic(cat_name);
   if (!cat) {
      return 1;
   }

   ast_category_append(args->cfg, cat);

   for (i = 0; i < argc; i++) {
      if (!argv[i]) {
         continue;
      }

      if (!(var = ast_variable_new(columnNames[i], argv[i], ""))) {
         ast_log(LOG_WARNING, "Unable to allocate variable\n");
         return 1;
      }

      ast_variable_append(cat, var);
   }

   return 0;
}

static struct ast_config *realtime_multi_handler(const char *database,
   const char *table, const struct ast_variable *fields)
{
   char *query, *errormsg = NULL, *op, *tmp_str, *initfield;
   struct rt_multi_cfg_entry_args args;
   const struct ast_variable *field = fields;
   struct ast_config *cfg;
   int error;

   if (!table) {
      ast_log(LOG_WARNING, "Table name unspecified\n");
      return NULL;
   }

   if (!fields) {
      return NULL;
   }

   if (!(cfg = ast_config_new())) {
      ast_log(LOG_WARNING, "Unable to allocate configuration structure\n");
      return NULL;
   }

   if (!(initfield = ast_strdup(field->name))) {
      ast_config_destroy(cfg);
      return NULL;
   }

   tmp_str = strchr(initfield, ' ');

   if (tmp_str)
      *tmp_str = '\0';

   op = (!strchr(field->name, ' ')) ? " =" : "";

   /*
    * Asterisk sends us an already escaped string when searching for
    * "exten LIKE" (uh!). Handle it separately.
    */
   tmp_str = (!strcmp(field->value, "\\_%")) ? "_%" : (char *)field->value;

/* \cond DOXYGEN_CAN_PARSE_THIS */
#undef QUERY
#define QUERY "SELECT * FROM '%q' WHERE%s %q%s '%q'"
/* \endcond */

   if (!(query = sqlite_mprintf(QUERY, table, (config_table && !strcmp(config_table, table)) ? " commented = 0 AND" : "", field->name, op, tmp_str))) {
      ast_log(LOG_WARNING, "Unable to allocate SQL query\n");
      ast_config_destroy(cfg);
      ast_free(initfield);
      return NULL;
   }

   while ((field = field->next)) {
      op = (!strchr(field->name, ' ')) ? " =" : "";
      tmp_str = sqlite_mprintf("%s AND %q%s '%q'", query, field->name, op, field->value);
      sqlite_freemem(query);

      if (!tmp_str) {
         ast_log(LOG_WARNING, "Unable to reallocate SQL query\n");
         ast_config_destroy(cfg);
         ast_free(initfield);
         return NULL;
      }

      query = tmp_str;
   }

   if (!(tmp_str = sqlite_mprintf("%s ORDER BY %q;", query, initfield))) {
      ast_log(LOG_WARNING, "Unable to reallocate SQL query\n");
      sqlite_freemem(query);
      ast_config_destroy(cfg);
      ast_free(initfield);
      return NULL;
   }

   sqlite_freemem(query);
   query = tmp_str;
   ast_debug(1, "SQL query: %s\n", query);
   args.cfg = cfg;
   args.initfield = initfield;

   ast_mutex_lock(&mutex);

   RES_CONFIG_SQLITE_BEGIN
      error = sqlite_exec(db, query, add_rt_multi_cfg_entry, &args, &errormsg);
   RES_CONFIG_SQLITE_END(error)

   ast_mutex_unlock(&mutex);

   sqlite_freemem(query);
   ast_free(initfield);

   if (error) {
      ast_log(LOG_WARNING, "%s\n", S_OR(errormsg, sqlite_error_string(error)));
      sqlite_freemem(errormsg);
      ast_config_destroy(cfg);
      return NULL;
   }
   sqlite_freemem(errormsg);

   return cfg;
}

static int realtime_update_handler(const char *database, const char *table,
   const char *keyfield, const char *entity, const struct ast_variable *fields)
{
   char *query, *errormsg = NULL, *tmp_str;
   const struct ast_variable *field = fields;
   int error, rows_num;

   if (!table) {
      ast_log(LOG_WARNING, "Table name unspecified\n");
      return -1;
   }

   if (!field) {
      return -1;
   }

/* \cond DOXYGEN_CAN_PARSE_THIS */
#undef QUERY
#define QUERY "UPDATE '%q' SET %q = '%q'"
/* \endcond */

   if (!(query = sqlite_mprintf(QUERY, table, field->name, field->value))) {
      ast_log(LOG_WARNING, "Unable to allocate SQL query\n");
      return -1;
   }

   while ((field = field->next)) {
      tmp_str = sqlite_mprintf("%s, %q = '%q'", query, field->name, field->value);
      sqlite_freemem(query);

      if (!tmp_str) {
         ast_log(LOG_WARNING, "Unable to reallocate SQL query\n");
         return -1;
      }

      query = tmp_str;
   }

   if (!(tmp_str = sqlite_mprintf("%s WHERE %q = '%q';", query, keyfield, entity))) {
      ast_log(LOG_WARNING, "Unable to reallocate SQL query\n");
      sqlite_freemem(query);
      return -1;
   }

   sqlite_freemem(query);
   query = tmp_str;
   ast_debug(1, "SQL query: %s\n", query);

   ast_mutex_lock(&mutex);

   RES_CONFIG_SQLITE_BEGIN
      error = sqlite_exec(db, query, NULL, NULL, &errormsg);
   RES_CONFIG_SQLITE_END(error)

   if (!error)
      rows_num = sqlite_changes(db);
   else
      rows_num = -1;

   ast_mutex_unlock(&mutex);

   sqlite_freemem(query);

   if (error) {
      ast_log(LOG_WARNING, "%s\n", S_OR(errormsg, sqlite_error_string(error)));
   }
   sqlite_freemem(errormsg);

   return rows_num;
}

static int realtime_update2_handler(const char *database, const char *table,
   const struct ast_variable *lookup_fields, const struct ast_variable *update_fields)
{
   char *errormsg = NULL, *tmp1, *tmp2;
   int error, rows_num, first = 1;
   struct ast_str *sql = ast_str_thread_get(&sql_buf, 100);
   struct ast_str *where = ast_str_thread_get(&where_buf, 100);
   const struct ast_variable *field;

   if (!table) {
      ast_log(LOG_WARNING, "Table name unspecified\n");
      return -1;
   }

   if (!sql) {
      return -1;
   }

   ast_str_set(&sql, 0, "UPDATE %s SET", table);
   ast_str_set(&where, 0, " WHERE");

   for (field = lookup_fields; field; field = field->next) {
      ast_str_append(&where, 0, "%s %s = %s",
         first ? "" : " AND",
         tmp1 = sqlite_mprintf("%q", field->name),
         tmp2 = sqlite_mprintf("%Q", field->value));
      sqlite_freemem(tmp1);
      sqlite_freemem(tmp2);
      first = 0;
   }

   if (first) {
      ast_log(LOG_ERROR, "No criteria specified on update to '%s@%s'!\n", table, database);
      return -1;
   }

   first = 1;
   for (field = update_fields; field; field = field->next) {
      ast_str_append(&sql, 0, "%s %s = %s",
         first ? "" : ",",
         tmp1 = sqlite_mprintf("%q", field->name),
         tmp2 = sqlite_mprintf("%Q", field->value));
      sqlite_freemem(tmp1);
      sqlite_freemem(tmp2);
      first = 0;
   }

   ast_str_append(&sql, 0, " %s", ast_str_buffer(where));
   ast_debug(1, "SQL query: %s\n", ast_str_buffer(sql));

   ast_mutex_lock(&mutex);

   RES_CONFIG_SQLITE_BEGIN
      error = sqlite_exec(db, ast_str_buffer(sql), NULL, NULL, &errormsg);
   RES_CONFIG_SQLITE_END(error)

   if (!error) {
      rows_num = sqlite_changes(db);
   } else {
      rows_num = -1;
   }

   ast_mutex_unlock(&mutex);

   if (error) {
      ast_log(LOG_WARNING, "%s\n", S_OR(errormsg, sqlite_error_string(error)));
   }
   sqlite_freemem(errormsg);

   return rows_num;
}

static int realtime_store_handler(const char *database, const char *table, const struct ast_variable *fields)
{
   char *errormsg = NULL, *tmp_str, *tmp_keys = NULL, *tmp_keys2 = NULL, *tmp_vals = NULL, *tmp_vals2 = NULL;
   const struct ast_variable *field = fields;
   int error, rows_id;

   if (!table) {
      ast_log(LOG_WARNING, "Table name unspecified\n");
      return -1;
   }

   if (!fields) {
      return -1;
   }

/* \cond DOXYGEN_CAN_PARSE_THIS */
#undef QUERY
#define QUERY "INSERT into '%q' (%s) VALUES (%s);"
/* \endcond */

   do {
      if ( tmp_keys2 ) {
         tmp_keys = sqlite_mprintf("%s, %q", tmp_keys2, field->name);
         sqlite_freemem(tmp_keys2);
      } else {
         tmp_keys = sqlite_mprintf("%q", field->name);
      }
      if (!tmp_keys) {
         ast_log(LOG_WARNING, "Unable to reallocate SQL query\n");
         sqlite_freemem(tmp_vals);
         return -1;
      }

      if ( tmp_vals2 ) {
         tmp_vals = sqlite_mprintf("%s, '%q'", tmp_vals2, field->value);
         sqlite_freemem(tmp_vals2);
      } else {
         tmp_vals = sqlite_mprintf("'%q'", field->value);
      }
      if (!tmp_vals) {
         ast_log(LOG_WARNING, "Unable to reallocate SQL query\n");
         sqlite_freemem(tmp_keys);
         return -1;
      }


      tmp_keys2 = tmp_keys;
      tmp_vals2 = tmp_vals;
   } while ((field = field->next));

   if (!(tmp_str = sqlite_mprintf(QUERY, table, tmp_keys, tmp_vals))) {
      ast_log(LOG_WARNING, "Unable to reallocate SQL query\n");
      sqlite_freemem(tmp_keys);
      sqlite_freemem(tmp_vals);
      return -1;
   }

   sqlite_freemem(tmp_keys);
   sqlite_freemem(tmp_vals);

   ast_debug(1, "SQL query: %s\n", tmp_str);

   ast_mutex_lock(&mutex);

   RES_CONFIG_SQLITE_BEGIN
      error = sqlite_exec(db, tmp_str, NULL, NULL, &errormsg);
   RES_CONFIG_SQLITE_END(error)

   if (!error) {
      rows_id = sqlite_last_insert_rowid(db);
   } else {
      rows_id = -1;
   }

   ast_mutex_unlock(&mutex);

   sqlite_freemem(tmp_str);

   if (error) {
      ast_log(LOG_WARNING, "%s\n", S_OR(errormsg, sqlite_error_string(error)));
   }
   sqlite_freemem(errormsg);

   return rows_id;
}

static int realtime_destroy_handler(const char *database, const char *table,
   const char *keyfield, const char *entity, const struct ast_variable *fields)
{
   char *query, *errormsg = NULL, *tmp_str;
   const struct ast_variable *field;
   int error, rows_num;

   if (!table) {
      ast_log(LOG_WARNING, "Table name unspecified\n");
      return -1;
   }

/* \cond DOXYGEN_CAN_PARSE_THIS */
#undef QUERY
#define QUERY "DELETE FROM '%q' WHERE"
/* \endcond */

   if (!(query = sqlite_mprintf(QUERY, table))) {
      ast_log(LOG_WARNING, "Unable to allocate SQL query\n");
      return -1;
   }

   for (field = fields; field; field = field->next) {
      tmp_str = sqlite_mprintf("%s %q = '%q' AND", query, field->name, field->value);
      sqlite_freemem(query);

      if (!tmp_str) {
         ast_log(LOG_WARNING, "Unable to reallocate SQL query\n");
         return -1;
      }

      query = tmp_str;
   }

   if (!(tmp_str = sqlite_mprintf("%s %q = '%q';", query, keyfield, entity))) {
      ast_log(LOG_WARNING, "Unable to reallocate SQL query\n");
      sqlite_freemem(query);
      return -1;
   }
   sqlite_freemem(query);
   query = tmp_str;
   ast_debug(1, "SQL query: %s\n", query);

   ast_mutex_lock(&mutex);

   RES_CONFIG_SQLITE_BEGIN
      error = sqlite_exec(db, query, NULL, NULL, &errormsg);
   RES_CONFIG_SQLITE_END(error)

   if (!error) {
      rows_num = sqlite_changes(db);
   } else {
      rows_num = -1;
   }

   ast_mutex_unlock(&mutex);

   sqlite_freemem(query);

   if (error) {
      ast_log(LOG_WARNING, "%s\n", S_OR(errormsg, sqlite_error_string(error)));
   }
   sqlite_freemem(errormsg);

   return rows_num;
}

static int realtime_require_handler(const char *unused, const char *tablename, va_list ap)
{
   struct sqlite_cache_tables *tbl = find_table(tablename);
   struct sqlite_cache_columns *col;
   char *elm;
   int type, res = 0;

   if (!tbl) {
      return -1;
   }

   while ((elm = va_arg(ap, char *))) {
      type = va_arg(ap, require_type);
      va_arg(ap, int);
      /* Check if the field matches the criteria */
      AST_RWLIST_TRAVERSE(&tbl->columns, col, list) {
         if (strcmp(col->name, elm) == 0) {
            /* SQLite only has two types - the 32-bit integer field that
             * is the key column, and everything else (everything else
             * being a string).
             */
            if (col->isint && !ast_rq_is_int(type)) {
               ast_log(LOG_WARNING, "Realtime table %s: column '%s' is an integer field, but Asterisk requires that it not be!\n", tablename, col->name);
               res = -1;
            }
            break;
         }
      }
      if (!col) {
         ast_log(LOG_WARNING, "Realtime table %s requires column '%s', but that column does not exist!\n", tablename, elm);
      }
   }
   AST_RWLIST_UNLOCK(&(tbl->columns));
   return res;
}

static int realtime_unload_handler(const char *unused, const char *tablename)
{
   struct sqlite_cache_tables *tbl;
   AST_RWLIST_WRLOCK(&sqlite_tables);
   AST_RWLIST_TRAVERSE_SAFE_BEGIN(&sqlite_tables, tbl, list) {
      if (!strcasecmp(tbl->name, tablename)) {
         AST_RWLIST_REMOVE_CURRENT(list);
         free_table(tbl);
      }
   }
   AST_RWLIST_TRAVERSE_SAFE_END
   AST_RWLIST_UNLOCK(&sqlite_tables);
   return 0;
}

static char *handle_cli_show_sqlite_status(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   switch (cmd) {
   case CLI_INIT:
      e->command = "sqlite show status";
      e->usage =
         "Usage: sqlite show status\n"
         "       Show status information about the SQLite 2 driver\n";
      return NULL;
   case CLI_GENERATE:
      return NULL;
   }

   if (a->argc != 3)
      return CLI_SHOWUSAGE;

   ast_cli(a->fd, "SQLite database path: %s\n", dbfile);
   ast_cli(a->fd, "config_table: ");

   if (!config_table)
      ast_cli(a->fd, "unspecified, must be present in extconfig.conf\n");
   else
      ast_cli(a->fd, "%s\n", config_table);

   ast_cli(a->fd, "cdr_table: ");

   if (!cdr_table)
      ast_cli(a->fd, "unspecified, CDR support disabled\n");
   else
      ast_cli(a->fd, "%s\n", cdr_table);

   return CLI_SUCCESS;
}

static char *handle_cli_sqlite_show_tables(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   struct sqlite_cache_tables *tbl;
   struct sqlite_cache_columns *col;
   int found = 0;

   switch (cmd) {
   case CLI_INIT:
      e->command = "sqlite show tables";
      e->usage =
         "Usage: sqlite show tables\n"
         "       Show table information about the SQLite 2 driver\n";
      return NULL;
   case CLI_GENERATE:
      return NULL;
   }

   if (a->argc != 3)
      return CLI_SHOWUSAGE;

   AST_RWLIST_RDLOCK(&sqlite_tables);
   AST_RWLIST_TRAVERSE(&sqlite_tables, tbl, list) {
      found++;
      ast_cli(a->fd, "Table %s:\n", tbl->name);
      AST_RWLIST_TRAVERSE(&(tbl->columns), col, list) {
         fprintf(stderr, "%s\n", col->name);
         ast_cli(a->fd, "  %20.20s  %-30.30s\n", col->name, col->type);
      }
   }
   AST_RWLIST_UNLOCK(&sqlite_tables);

   if (!found) {
      ast_cli(a->fd, "No tables currently in cache\n");
   }

   return CLI_SUCCESS;
}

static int unload_module(void)
{
   if (cdr_registered && ast_cdr_unregister(RES_CONFIG_SQLITE_NAME)) {
      return -1;
   }

   if (cli_status_registered) {
      ast_cli_unregister_multiple(cli_status, ARRAY_LEN(cli_status));
   }

   ast_config_engine_deregister(&sqlite_engine);

   if (db)
      sqlite_close(db);

   unload_config();

   return 0;
}

/*!
 * \brief Load the module
 *
 * Module loading including tests for configuration or dependencies.
 * This function can return AST_MODULE_LOAD_FAILURE, AST_MODULE_LOAD_DECLINE,
 * or AST_MODULE_LOAD_SUCCESS. If a dependency or environment variable fails
 * tests return AST_MODULE_LOAD_FAILURE. If the module can not load the
 * configuration file or other non-critical problem return
 * AST_MODULE_LOAD_DECLINE. On success return AST_MODULE_LOAD_SUCCESS.
 */
static int load_module(void)
{
   char *errormsg = NULL;
   int error;

   db = NULL;
   cdr_registered = 0;
   cli_status_registered = 0;
   dbfile = NULL;
   config_table = NULL;
   cdr_table = NULL;
   error = load_config();

   if (error)
      return AST_MODULE_LOAD_DECLINE;

   if (!(db = sqlite_open(dbfile, 0660, &errormsg))) {
      ast_log(LOG_ERROR, "%s\n", S_OR(errormsg, sqlite_error_string(error)));
      sqlite_freemem(errormsg);
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   sqlite_freemem(errormsg);
   errormsg = NULL;
   ast_config_engine_register(&sqlite_engine);

   if (use_cdr) {
      char *query;

/* \cond DOXYGEN_CAN_PARSE_THIS */
#undef QUERY
#define QUERY "SELECT COUNT(id) FROM %Q;"
/* \endcond */

      query = sqlite_mprintf(QUERY, cdr_table);

      if (!query) {
         ast_log(LOG_ERROR, "Unable to allocate SQL query\n");
         unload_module();
         return AST_MODULE_LOAD_DECLINE;
      }

      ast_debug(1, "SQL query: %s\n", query);

      RES_CONFIG_SQLITE_BEGIN
         error = sqlite_exec(db, query, NULL, NULL, &errormsg);
      RES_CONFIG_SQLITE_END(error)

      sqlite_freemem(query);

      if (error) {
         /*
          * Unexpected error.
          */
         if (error != SQLITE_ERROR) {
            ast_log(LOG_ERROR, "%s\n", S_OR(errormsg, sqlite_error_string(error)));
            sqlite_freemem(errormsg);
            unload_module();
            return AST_MODULE_LOAD_DECLINE;
         }

         sqlite_freemem(errormsg);
         errormsg = NULL;
         query = sqlite_mprintf(sql_create_cdr_table, cdr_table);

         if (!query) {
            ast_log(LOG_ERROR, "Unable to allocate SQL query\n");
            unload_module();
            return AST_MODULE_LOAD_DECLINE;
         }

         ast_debug(1, "SQL query: %s\n", query);

         RES_CONFIG_SQLITE_BEGIN
            error = sqlite_exec(db, query, NULL, NULL, &errormsg);
         RES_CONFIG_SQLITE_END(error)

         sqlite_freemem(query);

         if (error) {
            ast_log(LOG_ERROR, "%s\n", S_OR(errormsg, sqlite_error_string(error)));
            sqlite_freemem(errormsg);
            unload_module();
            return AST_MODULE_LOAD_DECLINE;
         }
      }
      sqlite_freemem(errormsg);
      errormsg = NULL;

      error = ast_cdr_register(RES_CONFIG_SQLITE_NAME, RES_CONFIG_SQLITE_DESCRIPTION, cdr_handler);

      if (error) {
         unload_module();
         return AST_MODULE_LOAD_DECLINE;
      }

      cdr_registered = 1;
   }

   error = ast_cli_register_multiple(cli_status, ARRAY_LEN(cli_status));

   if (error) {
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   cli_status_registered = 1;

   return AST_MODULE_LOAD_SUCCESS;
}

/*
 * This module should require "cdr" to enforce startup/shutdown ordering but it
 * loads at REALTIME_DRIVER priority which would cause "cdr" to load too early.
 *
 * ast_cdr_register / ast_cdr_unregister is safe for use while "cdr" is not running.
 */
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Realtime SQLite configuration",
   .support_level = AST_MODULE_SUPPORT_DEPRECATED,
   .load = load_module,
   .unload = unload_module,
   .load_pri = AST_MODPRI_REALTIME_DRIVER,
   .requires = "extconfig",
);