new

static VALUE
fsdbm_initialize(int argc, VALUE *argv, VALUE obj)
{
    volatile VALUE file;
    VALUE vmode;
    DBM *dbm;
    struct dbmdata *dbmp;
    int mode;

    if (rb_scan_args(argc, argv, "11", &file, &vmode) == 1) {
        mode = 0666;           /* default value */
    }
    else if (NIL_P(vmode)) {
        mode = -1;             /* return nil if DB not exist */
    }
    else {
        mode = NUM2INT(vmode);
    }
    FilePathValue(file);

    dbm = 0;
    if (mode >= 0)
        dbm = sdbm_open(RSTRING_PTR(file), O_RDWR|O_CREAT, mode);
    if (!dbm)
        dbm = sdbm_open(RSTRING_PTR(file), O_RDWR, 0);
    if (!dbm)
        dbm = sdbm_open(RSTRING_PTR(file), O_RDONLY, 0);

    if (!dbm) {
        if (mode == -1) return Qnil;
        rb_sys_fail(RSTRING_PTR(file));
    }

    dbmp = ALLOC(struct dbmdata);
    DATA_PTR(obj) = dbmp;
    dbmp->di_dbm = dbm;
    dbmp->di_size = -1;

    return obj;
}