diff options
Diffstat (limited to 'src/serialbus/qmodbuspdu.cpp')
-rw-r--r-- | src/serialbus/qmodbuspdu.cpp | 107 |
1 files changed, 61 insertions, 46 deletions
diff --git a/src/serialbus/qmodbuspdu.cpp b/src/serialbus/qmodbuspdu.cpp index 9ca9027..d97d614 100644 --- a/src/serialbus/qmodbuspdu.cpp +++ b/src/serialbus/qmodbuspdu.cpp @@ -48,13 +48,23 @@ Q_GLOBAL_STATIC(ReqSizeCalc, requestSizeCalculators); using ResSizeCalc = QHash<quint8, QModbusResponse::CalcFuncPtr>; Q_GLOBAL_STATIC(ResSizeCalc, responseSizeCalculators); -namespace Private { +struct QModbusPduPrivate +{ + QModbusPduPrivate() = delete; + Q_DISABLE_COPY_MOVE(QModbusPduPrivate) enum struct Type { Request, Response }; +/*! + \internal + + Returns the minimum data size in bytes for the given \a pdu and the + Modbus PDU \a type. If the PDU's function code is invalid, undefined + or unknown, the return value will be \c {-1}. +*/ static int minimumDataSize(const QModbusPdu &pdu, Type type) { if (pdu.isException()) @@ -103,44 +113,53 @@ static int minimumDataSize(const QModbusPdu &pdu, Type type) return -1; } -static QDataStream &pduFromStream(QDataStream &stream, QModbusPdu &pdu, Type type) +/*! + \internal + + Extracts a Modbus PDU from a \a stream into the given \a pdu based on \a type. +*/ +static QDataStream &pduFromStream(QDataStream &stream, Type type, QModbusPdu *pdu) { - quint8 codeByte = 0; - if (stream.readRawData(reinterpret_cast<char *>(&codeByte), sizeof(quint8)) != sizeof(quint8)) + struct RAII { + RAII(QModbusPdu *ptr = nullptr) + : tmp(ptr) {} + QModbusPdu *tmp{ nullptr }; + ~RAII() { if (tmp) *tmp = {}; } + } raii = { pdu }; + + QModbusPdu::FunctionCode code = QModbusPdu::FunctionCode::Invalid; + if (stream.readRawData(reinterpret_cast<char *>(&code), sizeof(quint8)) != sizeof(quint8)) return stream; - QModbusPdu::FunctionCode code = QModbusPdu::FunctionCode(codeByte); - pdu.setFunctionCode(code); + pdu->setFunctionCode(code); - auto needsAdditionalRead = [](QModbusPdu &pdu, int size) -> bool { - if (size < 0) - pdu.setFunctionCode(QModbusResponse::Invalid); - if (size <= 0) - return false; - return true; - }; - - const bool isResponse = (type == Type::Response); - int size = isResponse ? QModbusResponse::minimumDataSize(pdu) - : QModbusRequest::minimumDataSize(pdu); - if (!needsAdditionalRead(pdu, size)) + if (code == QModbusPdu::Invalid || code == QModbusPdu::UndefinedFunctionCode) // shortcut return stream; - QByteArray data(size, Qt::Uninitialized); - if (stream.device()->peek(data.data(), data.size()) != size) - return stream; + constexpr const int MaxPduDataSize = 252; // in bytes - pdu.setData(data); - size = isResponse ? QModbusResponse::calculateDataSize(pdu) - : QModbusRequest::calculateDataSize(pdu); - if (!needsAdditionalRead(pdu, size)) + // The calculateDataSize(...) function might need some data inside the + // given PDU argument to be able to figure out the right data size (e.g. + // WriteMultipleCoils contains some kind of "header"). So fake fill the PDU + // with the maximum available data but no more than the allowed max PDU + // data size. + QByteArray data(MaxPduDataSize, Qt::Uninitialized); + int read = stream.device()->peek(data.data(), MaxPduDataSize); + if (read < 0) return stream; + data.resize(read); + pdu->setData(data); + + const bool isResponse = (type == Type::Response); + int size = isResponse ? QModbusResponse::calculateDataSize(*pdu) + : QModbusRequest::calculateDataSize(*pdu); + if (isResponse && (code == QModbusPdu::EncapsulatedInterfaceTransport)) { quint8 meiType; - pdu.decodeData(&meiType); + pdu->decodeData(&meiType); if (meiType == EncapsulatedInterfaceTransport::ReadDeviceIdentification) { int left = size, offset = 0; - while ((left > 0) && (size <= 252)) { // The maximum PDU data size is 252 bytes. + while ((left > 0) && (size <= MaxPduDataSize)) { data.resize(size); const int read = stream.readRawData(data.data() + offset, size - offset); if ((read < 0) || (read != (size - offset))) { @@ -152,35 +171,31 @@ static QDataStream &pduFromStream(QDataStream &stream, QModbusPdu &pdu, Type typ left = QModbusResponse::calculateDataSize(QModbusResponse(code, data)) - offset; size += left; } - if ((stream.status() == QDataStream::Ok) && (size <= 252)) { - pdu.setData(data); + if ((stream.status() == QDataStream::Ok) && (size <= MaxPduDataSize)) { + raii = {}; + pdu->setData(data); return stream; // early return to avoid second read } } else { data.resize(int(stream.device()->size() - 1)); // One byte for the function code. } - } else if (pdu.functionCode() == QModbusPdu::Diagnostics) { + } else if (pdu->functionCode() == QModbusPdu::Diagnostics) { quint16 subCode; - pdu.decodeData(&subCode); + pdu->decodeData(&subCode); if (subCode == Diagnostics::ReturnQueryData) data.resize(int(stream.device()->size() - 1)); // One byte for the function code. } - // reset what we have so far, next read might fail as well - pdu.setData(QByteArray()); - pdu.setFunctionCode(QModbusPdu::Invalid); - - if (data.size() <= 252) { // The maximum PDU data size is 252 bytes. + if (data.size() <= MaxPduDataSize) { data.resize(size); if (stream.readRawData(data.data(), data.size()) == size) { - pdu.setData(data); - pdu.setFunctionCode(code); + raii = {}; + pdu->setData(data); } } return stream; } - -} // namespace Private +}; /*! \class QModbusPdu @@ -533,7 +548,7 @@ QDataStream &operator<<(QDataStream &stream, const QModbusPdu &pdu) */ int QModbusRequest::minimumDataSize(const QModbusRequest &request) { - return Private::minimumDataSize(request, Private::Type::Request); + return QModbusPduPrivate::minimumDataSize(request, QModbusPduPrivate::Type::Request); } /*! @@ -555,7 +570,7 @@ int QModbusRequest::calculateDataSize(const QModbusRequest &request) return 1; int size = -1; - int minimum = Private::minimumDataSize(request, Private::Type::Request); + int minimum = QModbusPduPrivate::minimumDataSize(request, QModbusPduPrivate::Type::Request); if (minimum < 0) return size; @@ -620,7 +635,7 @@ void QModbusRequest::registerDataSizeCalculator(FunctionCode fc, CalcFuncPtr cal */ QDataStream &operator>>(QDataStream &stream, QModbusRequest &pdu) { - return Private::pduFromStream(stream, pdu, Private::Type::Request); + return QModbusPduPrivate::pduFromStream(stream, QModbusPduPrivate::Type::Request, &pdu); } /*! @@ -689,7 +704,7 @@ QDataStream &operator>>(QDataStream &stream, QModbusRequest &pdu) */ int QModbusResponse::minimumDataSize(const QModbusResponse &response) { - return Private::minimumDataSize(response, Private::Type::Response); + return QModbusPduPrivate::minimumDataSize(response, QModbusPduPrivate::Type::Response); } /*! @@ -711,7 +726,7 @@ int QModbusResponse::calculateDataSize(const QModbusResponse &response) return 1; int size = -1; - int minimum = Private::minimumDataSize(response, Private::Type::Response); + int minimum = QModbusPduPrivate::minimumDataSize(response, QModbusPduPrivate::Type::Response); if (minimum < 0) return size; @@ -806,7 +821,7 @@ void QModbusResponse::registerDataSizeCalculator(FunctionCode fc, CalcFuncPtr ca */ QDataStream &operator>>(QDataStream &stream, QModbusResponse &pdu) { - return Private::pduFromStream(stream, pdu, Private::Type::Response); + return QModbusPduPrivate::pduFromStream(stream, QModbusPduPrivate::Type::Response, &pdu); } /*! |