** zDbName is NULL. Returns NULL if globalDb is not opened.
*/
const char * fiddle_db_filename(const char * zDbName){
    return globalDb
      ? sqlite3_db_filename(globalDb, zDbName ? zDbName : "main")
      : NULL;
}

/*
** Closes, unlinks, and reopens the db using its current filename (or
** the default if the db is currently closed). It is assumed, for
** purposes of the fiddle build, that the file is in a transient
** virtual filesystem within the browser.
*/
void fiddle_reset_db(void){
  char *zFilename = 0;
  if(0==globalDb){
    shellState.pAuxDb->zDbFilename = "/fiddle.sqlite3";
  }else{
    zFilename =
      sqlite3_mprintf("%s", sqlite3_db_filename(globalDb, "main"));
    shell_check_oom(zFilename);
    close_db(globalDb);
    shellDeleteFile(zFilename);
    shellState.db = 0;
    shellState.pAuxDb->zDbFilename = zFilename;
  }
  open_db(&shellState, 0);
  sqlite3_free(zFilename);
}

/*
** Trivial exportable function for emscripten. Needs to be exported using:
**
** emcc ..flags... -sEXPORTED_FUNCTIONS=_fiddle_exec -sEXPORTED_RUNTIME_METHODS=ccall,cwrap
**
** (Note the underscore before the function name.) It processes zSql

    printf(
        "SQLite version %s %.19s\n" /*extra-version-info*/,
        sqlite3_libversion(), sqlite3_sourceid()
    );
    puts("WASM shell");
    puts("Enter \".help\" for usage hints.");
    if(once>0){

      fiddle_reset_db();
    }
    if(shellState.db){
      printf("Connected to %s.\n", fiddle_db_filename(NULL));
    }else{
      fprintf(stderr,"ERROR initializing db!\n");
      return;
    }