** A function that loads a shared-library extension then returns NULL.
*/
static void loadExt(sqlite3_context *context, int argc, sqlite3_value **argv){
  const char *zFile = (const char *)sqlite3_value_text(argv[0]);
  const char *zProc;
  sqlite3 *db = sqlite3_context_db_handle(context);
  char *zErrMsg = 0;

  /* Disallow the load_extension() SQL function unless the SQLITE_LoadExtFunc
  ** flag is set.  See the sqlite3_enable_load_extension() API.
  */
  if( (db->flags & SQLITE_LoadExtFunc)==0 ){
    sqlite3_result_error(context, "not authorized", -1);
    return;
  }

  if( argc==2 ){
    zProc = (const char *)sqlite3_value_text(argv[1]);
  }else{
    zProc = 0;
  }
  if( zFile && sqlite3_load_extension(db, zFile, zProc, &zErrMsg) ){

  if( pzErrMsg ) *pzErrMsg = 0;

  /* Ticket #1863.  To avoid a creating security problems for older
  ** applications that relink against newer versions of SQLite, the
  ** ability to run load_extension is turned off by default.  One
  ** must call either sqlite3_enable_load_extension(db) or
  ** sqlite3_db_config(db, SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION, 1, 0)
  ** to turn on extension loading.
  */
  if( (db->flags & SQLITE_LoadExtension)==0 ){
    if( pzErrMsg ){
      *pzErrMsg = sqlite3_mprintf("not authorized");
    }
    return SQLITE_ERROR;
  }

/*
** Enable or disable extension loading.  Extension loading is disabled by
** default so as not to open security holes in older applications.
*/
int sqlite3_enable_load_extension(sqlite3 *db, int onoff){
  sqlite3_mutex_enter(db->mutex);
  if( onoff ){
    db->flags |= SQLITE_LoadExtension|SQLITE_LoadExtFunc;
  }else{
    db->flags &= ~(SQLITE_LoadExtension|SQLITE_LoadExtFunc);
  }
  sqlite3_mutex_leave(db->mutex);
  return SQLITE_OK;
}

#endif /* SQLITE_OMIT_LOAD_EXTENSION */

      static const struct {
        int op;      /* The opcode */
        u32 mask;    /* Mask of the bit in sqlite3.flags to set/clear */
      } aFlagOp[] = {
        { SQLITE_DBCONFIG_ENABLE_FKEY,           SQLITE_ForeignKeys    },
        { SQLITE_DBCONFIG_ENABLE_TRIGGER,        SQLITE_EnableTrigger  },
        { SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER, SQLITE_Fts3Tokenizer  },
        { SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION, SQLITE_LoadExtension  },
      };
      unsigned int i;
      rc = SQLITE_ERROR; /* IMP: R-42790-23372 */
      for(i=0; i<ArraySize(aFlagOp); i++){
        if( aFlagOp[i].op==op ){
          int onoff = va_arg(ap, int);
          int *pRes = va_arg(ap, int*);

** positive to enable fts3_tokenizer() or negative to leave the setting
** unchanged.
** The second parameter is a pointer to an integer into which
** is written 0 or 1 to indicate whether fts3_tokenizer is disabled or enabled
** following this call.  The second parameter may be a NULL pointer, in
** which case the new setting is not reported back. </dd>
**
** <dt>SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION</dt>
** <dd> ^This option is used to enable or disable the [sqlite3_load_extension()]
** interface independently of the [load_extension()] SQL function.
** The [sqlite3_enable_load_extension()] API enables or disables both the
** C-API [sqlite3_load_extension()] and the SQL function [load_extension()].
** There should be two additional arguments.
** When the first argument to this interface is 1, then only the C-API is
** enabled and the SQL function remains disabled.  If the first argment to
** this interface is 0, then both the C-API and the SQL function are disabled.
** If the first argument is -1, then no changes are made to state of either the
** C-API or the SQL function.
** The second parameter is a pointer to an integer into which
** is written 0 or 1 to indicate whether [sqlite3_load_extension()] interface
** is disabled or enabled following this call.  The second parameter may
** be a NULL pointer, in which case the new setting is not reported back.
** </dd>
**
** </dl>
*/
#define SQLITE_DBCONFIG_LOOKASIDE             1001 /* void* int int */
#define SQLITE_DBCONFIG_ENABLE_FKEY           1002 /* int int* */
#define SQLITE_DBCONFIG_ENABLE_TRIGGER        1003 /* int int* */
#define SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER 1004 /* int int* */
#define SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION 1005 /* int int* */


/*
** CAPI3REF: Enable Or Disable Extended Result Codes
** METHOD: sqlite3
**
** ^The sqlite3_extended_result_codes() routine enables or disables the

** ^If an error occurs and pzErrMsg is not 0, then the
** [sqlite3_load_extension()] interface shall attempt to
** fill *pzErrMsg with error message text stored in memory
** obtained from [sqlite3_malloc()]. The calling function
** should free this memory by calling [sqlite3_free()].
**
** ^Extension loading must be enabled using
** [sqlite3_enable_load_extension()] or
** [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],1,NULL)
** prior to calling this API,
** otherwise an error will be returned.
**
** <b>Security warning:</b> It is recommended that the 
** [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method be used to enable only this
** interface.  The use of the [sqlite3_enable_load_extension()] interface
** should be avoided.  This will keep the SQL function [load_extension()]
** disabled and prevent SQL injections from giving attackers
** access to extension loading capabilities.
**
** See also the [load_extension() SQL function].
*/
int sqlite3_load_extension(
  sqlite3 *db,          /* Load the extension into this database connection */
  const char *zFile,    /* Name of the shared library containing extension */
  const char *zProc,    /* Entry point.  Derived from zFile if 0 */

** [extension loading] while evaluating user-entered SQL, the following API
** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
**
** ^Extension loading is off by default.
** ^Call the sqlite3_enable_load_extension() routine with onoff==1
** to turn extension loading on and call it with onoff==0 to turn
** it back off again.
**
** ^This interface enables or disables both the C-API
** [sqlite3_load_extension()] and the SQL function [load_extension()].
** Use [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],..)
** to enable or disable only the C-API.
**
** <b>Security warning:</b> It is recommended that extension loading
** be disabled using the [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method
** rather than this interface, so the [load_extension()] SQL function
** remains disabled. This will prevent SQL injections from giving attackers
** access to extension loading capabilities.
*/
int sqlite3_enable_load_extension(sqlite3 *db, int onoff);

/*
** CAPI3REF: Automatically Load Statically Linked Extensions
**
** ^This interface causes the xEntryPoint() function to be invoked for

#define SQLITE_RecoveryMode   0x00010000  /* Ignore schema errors */
#define SQLITE_ReverseOrder   0x00020000  /* Reverse unordered SELECTs */
#define SQLITE_RecTriggers    0x00040000  /* Enable recursive triggers */
#define SQLITE_ForeignKeys    0x00080000  /* Enforce foreign key constraints  */
#define SQLITE_AutoIndex      0x00100000  /* Enable automatic indexes */
#define SQLITE_PreferBuiltin  0x00200000  /* Preference to built-in funcs */
#define SQLITE_LoadExtension  0x00400000  /* Enable load_extension */
#define SQLITE_LoadExtFunc    0x00800000  /* Enable load_extension() SQL func */
#define SQLITE_EnableTrigger  0x01000000  /* True to enable triggers */
#define SQLITE_DeferFKs       0x02000000  /* Defer all FK constraints */
#define SQLITE_QueryOnly      0x04000000  /* Disable database changes */
#define SQLITE_VdbeEQP        0x08000000  /* Debug EXPLAIN QUERY PLAN */
#define SQLITE_Vacuum         0x10000000  /* Currently in a VACUUM */
#define SQLITE_CellSizeCk     0x20000000  /* Check btree cell sizes on load */
#define SQLITE_Fts3Tokenizer  0x40000000  /* Enable fts3_tokenizer(2) */


/*
** Bits of the sqlite3.dbOptFlags field that are used by the
** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface to
** selectively disable various optimizations.
*/

  static const struct {
    const char *zName;
    int eVal;
  } aSetting[] = {
    { "FKEY",            SQLITE_DBCONFIG_ENABLE_FKEY },
    { "TRIGGER",         SQLITE_DBCONFIG_ENABLE_TRIGGER },
    { "FTS3_TOKENIZER",  SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER },
    { "LOAD_EXTENSION",  SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION },
  };
  int i;
  int v;
  const char *zSetting;
  sqlite3 *db;

  if( objc!=4 ){

  }
} {0 0.5}

# Test that a second database connection (db2) can load the extension also.
#
do_test loadext-1.3 {
  sqlite3 db2 test.db
  sqlite3_db_config db2 SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION 1
  catchsql {
    SELECT half(1.0);
  } db2
} {1 {no such function: half}}
do_test loadext-1.4 {
  sqlite3_load_extension db2 $testextension testloadext_init
  catchsql {

do_test loadext-4.2 {
  sqlite3_enable_load_extension db 1
  catchsql {
    SELECT load_extension($::testextension,'testloadext_init')
  }
} {0 {{}}}

# disable all extension loading
do_test loadext-4.3 {
  sqlite3_enable_load_extension db 0
  catchsql {
    SELECT load_extension($::testextension,'testloadext_init')
  }
} {1 {not authorized}}

# enable C-api extension loading only.  Show that the SQL function
# still does not work.
do_test loadext-4.4 {
  sqlite3_db_config db SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION 1
  catchsql {
    SELECT load_extension($::testextension,'testloadext_init')
  }
} {1 {not authorized}}

source $testdir/malloc_common.tcl