php - 如何为非常大的文件替换流中的字符串

Question

如何替换无法完全加载到内存中的文件中的字符串
我可以一次读取几个字节，但我如何确定我没有读到我的短语中间？
我想我应该保存最后strlen(phrase)的字节长度并尝试替换 last+current
这是我的 WIP

function stream_str_replace(string $search, string $replace, $handle, int $length, &$count = null)
{
    // assure $handle is a resource
    if (!is_resource($handle)) {
        throw new UnexpectedValueException('handle must be a valid stream resource');
    }

    // assure $handle is a stream resource
    if ($resourceType = get_resource_type($handle) !== 'stream') {
        throw new UnexpectedValueException('handle must be a valid stream resource, but is a "' . $resourceType . '"');
    }

    $sLength = strlen($search);

    $lastInSLength = '';
    while (!feof($handle)) {
        $str = fread($handle, $length - $sLength - 1);

        $batchCount = 0;
        $res = str_replace($search, $replace, $lastInSLength . $str, $batchCount);

        if ($batchCount) {
            $count += $batchCount;
            fseek($handle, -($length - 1));
            fwrite($handle, $res); // this does not seem to work as I intend it to
        }

        $lastInSLength = substr($str, -$sLength);
    }
}

$fh = fopen('sample.txt', 'r+');

stream_str_replace('consectetur', 'foo', $fh, 50, $count);

fclose($fh);