new

static VALUE
fdbm_initialize(int argc, VALUE *argv, VALUE obj)
{
    volatile VALUE file;
    VALUE vmode, vflags;
    DBM *dbm;
    struct dbmdata *dbmp;
    int mode, flags = 0;

    if (rb_scan_args(argc, argv, "12", &file, &vmode, &vflags) == 1) {
        mode = 0666;           /* default value */
    }
    else if (NIL_P(vmode)) {
        mode = -1;             /* return nil if DB not exist */
    }
    else {
        mode = NUM2INT(vmode);
    }

    if (!NIL_P(vflags))
        flags = NUM2INT(vflags);

    FilePathValue(file);

    if (flags & RUBY_DBM_RW_BIT) {
        flags &= ~RUBY_DBM_RW_BIT;
        dbm = dbm_open(RSTRING_PTR(file), flags, mode);
    }
    else {
        dbm = 0;
        if (mode >= 0) {
            dbm = dbm_open(RSTRING_PTR(file), O_RDWR|O_CREAT, mode);
        }
        if (!dbm) {
            dbm = dbm_open(RSTRING_PTR(file), O_RDWR, 0);
        }
        if (!dbm) {
            dbm = dbm_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;
}