Swift_Signers_SMimeSigner::streamToMime PHP Method

    protected function streamToMime(Swift_OutputByteStream $fromStream, Swift_Message $message)
    {
        $bufferLength = 78;
        $headerData = '';
        $fromStream->setReadPointer(0);
        while (($buffer = $fromStream->read($bufferLength)) !== false) {
            $headerData .= $buffer;
            if (false !== strpos($buffer, "\r\n\r\n")) {
                break;
            }
        }
        $headersPosEnd = strpos($headerData, "\r\n\r\n");
        $headerData = trim($headerData);
        $headerData = substr($headerData, 0, $headersPosEnd);
        $headerLines = explode("\r\n", $headerData);
        unset($headerData);
        $headers = array();
        $currentHeaderName = '';
        foreach ($headerLines as $headerLine) {
            // Line separated
            if (ctype_space($headerLines[0]) || false === strpos($headerLine, ':')) {
                $headers[$currentHeaderName] .= ' ' . trim($headerLine);
                continue;
            }
            $header = explode(':', $headerLine, 2);
            $currentHeaderName = strtolower($header[0]);
            $headers[$currentHeaderName] = trim($header[1]);
        }
        $messageStream = new Swift_ByteStream_TemporaryFileByteStream();
        $messageStream->addFilter($this->replacementFactory->createFilter("\r\n", "\n"), 'CRLF to LF');
        $messageStream->addFilter($this->replacementFactory->createFilter("\n", "\r\n"), 'LF to CRLF');
        $messageHeaders = $message->getHeaders();
        // No need to check for 'application/pkcs7-mime', as this is always base64
        if ('multipart/signed;' === substr($headers['content-type'], 0, 17)) {
            if (!preg_match('/boundary=("[^"]+"|(?:[^\\s]+|$))/is', $headers['content-type'], $contentTypeData)) {
                throw new Swift_SwiftException('Failed to find Boundary parameter');
            }
            $boundary = trim($contentTypeData['1'], '"');
            // Skip the header and CRLF CRLF
            $fromStream->setReadPointer($headersPosEnd + 4);
            while (false !== ($buffer = $fromStream->read($bufferLength))) {
                $messageStream->write($buffer);
            }
            $messageStream->commit();
            $messageHeaders->remove('Content-Transfer-Encoding');
            $message->setContentType($headers['content-type']);
            $message->setBoundary($boundary);
            $message->setBody($messageStream);
        } else {
            $fromStream->setReadPointer($headersPosEnd + 4);
            if (null === $this->headerFactory) {
                $this->headerFactory = Swift_DependencyContainer::getInstance()->lookup('mime.headerfactory');
            }
            $message->setContentType($headers['content-type']);
            $messageHeaders->set($this->headerFactory->createTextHeader('Content-Transfer-Encoding', $headers['content-transfer-encoding']));
            $messageHeaders->set($this->headerFactory->createTextHeader('Content-Disposition', $headers['content-disposition']));
            while (false !== ($buffer = $fromStream->read($bufferLength))) {
                $messageStream->write($buffer);
            }
            $messageStream->commit();
            $message->setBody($messageStream);
        }
    }