Fix tryToReadMeta(), introduce AbstractStreamReader::readCount()

Bytes read count cannot be taken from stream::tellg() because data might be read ahead from stream to read buffer
silicon-heaven · Dec 11, 2024 · 9ff4c60 · 9ff4c60
1 parent b798c44
commit 9ff4c60
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Showing 5 changed files with 45 additions and 54 deletions.
diff --git a/libshvchainpack/include/shv/chainpack/abstractstreamreader.h b/libshvchainpack/include/shv/chainpack/abstractstreamreader.h
@@ -32,6 +32,8 @@ class SHVCHAINPACK_DECL_EXPORT AbstractStreamReader
 
 	virtual void read(RpcValue::MetaData &meta_data) = 0;
 	virtual void read(RpcValue &val) = 0;
+
+	ssize_t readCount() const;
 protected:
 	// NOLINTNEXTLINE(cppcoreguidelines-avoid-const-or-ref-data-members)
 	std::istream &m_in;

diff --git a/libshvchainpack/src/abstractstreamreader.cpp b/libshvchainpack/src/abstractstreamreader.cpp
@@ -70,4 +70,13 @@ RpcValue AbstractStreamReader::read(std::string *error)
 	return ret;
 }
 
+ssize_t AbstractStreamReader::readCount() const
+{
+	ssize_t count = m_in.tellg();
+	if (count >= 0) {
+		count -= m_inCtx.end - m_inCtx.current;
+	}
+	return count;
+}
+
 } // namespace shv
diff --git a/libshvchainpack/src/chainpackreader.cpp b/libshvchainpack/src/chainpackreader.cpp
@@ -15,7 +15,7 @@ ChainPackReader::ChainPackReader(std::istream &in)
 void ChainPackReader::throwParseException(const std::string &msg)
 {
 	std::array<char, 64> buff;
-	auto err_pos = m_in.tellg();
+	auto err_pos = readCount();
 	auto l = m_in.readsome(buff.data(), buff.size() - 1);
 	buff[l] = 0;
 	auto dump = shv::chainpack::utils::hexDump(buff.data(), l);
@@ -256,8 +256,7 @@ void ChainPackReader::parseIMap(RpcValue &out_val)
 
 void ChainPackReader::read(RpcValue::MetaData &meta_data)
 {
-	auto b = reinterpret_cast<const uint8_t*>(ccpcp_unpack_take_byte(&m_inCtx));
-	m_inCtx.current--;
+	auto b = reinterpret_cast<const uint8_t*>(ccpcp_unpack_peek_byte(&m_inCtx));
 	if(b && *b == CP_MetaMap) {
 		cchainpack_unpack_next(&m_inCtx);
 		parseMetaData(meta_data);

diff --git a/libshvchainpack/src/cponreader.cpp b/libshvchainpack/src/cponreader.cpp
@@ -16,7 +16,7 @@ CponReader::CponReader(std::istream &in)
 void CponReader::throwParseException(const std::string &msg)
 {
 	std::array<char, 64> buff;
-	auto err_pos = m_in.tellg();
+	auto err_pos = readCount();
 	auto l = m_in.readsome(buff.data(), buff.size() - 1);
 	buff[l] = 0;
 	std::string msg2 = m_inCtx.err_msg? m_inCtx.err_msg: "";

diff --git a/libshvchainpack/src/rpcmessage.cpp b/libshvchainpack/src/rpcmessage.cpp
@@ -98,32 +98,23 @@ RpcMessage RpcFrame::toRpcMessage(std::string *errmsg) const
 
 std::string RpcFrame::toFrameHead() const
 {
+	std::ostringstream out;
+	std::unique_ptr<AbstractStreamWriter> wr;
 	switch (protocol) {
-	case Rpc::ProtocolType::ChainPack: {
-		std::ostringstream out;
-		{
-			ChainPackWriter wr(out);
-			wr << meta;
-		}
-		auto ret = out.str();
-		ret = static_cast<char>(protocol) + ret;
-		ret += data;
-		return ret;
-	}
-	case Rpc::ProtocolType::Cpon: {
-		std::ostringstream out;
-		{
-			CponWriter wr(out);
-			wr << meta;
-		}
-		auto ret = out.str();
-		ret = static_cast<char>(protocol) + ret;
-		return ret;
-	}
-	default: {
+	case Rpc::ProtocolType::ChainPack:
+		wr = std::make_unique<ChainPackWriter>(out);
+		break;
+	case Rpc::ProtocolType::Cpon:
+		wr = std::make_unique<CponWriter>(out);
+		break;
+	default:
 		throw std::runtime_error("Invalid protocol type");
 	}
-	}
+	wr->write(meta);
+	wr->flush();
+	auto ret = out.str();
+	ret = static_cast<char>(protocol) + ret;
+	return ret;
 }
 
 std::string RpcFrame::toFrameData() const
@@ -136,38 +127,28 @@ std::string RpcFrame::toFrameData() const
 RpcFrame RpcFrame::fromFrameData(const std::string &frame_data)
 {
 	std::istringstream in(frame_data);
+	std::unique_ptr<AbstractStreamReader> rd;
 	auto protocol = static_cast<Rpc::ProtocolType>(in.get());
 	switch (protocol) {
-	case Rpc::ProtocolType::ChainPack: {
-		ChainPackReader rd(in);
-		RpcValue::MetaData meta;
-		rd.read(meta);
-		if(meta.isEmpty())
-			throw ParseException(CCPCP_RC_MALFORMED_INPUT, "Metadata missing", -1, {});
-		auto pos = in.tellg();
-		if(pos < 0)
-			throw ParseException(CCPCP_RC_MALFORMED_INPUT, "Metadata missing", -1, {});
-		auto data = std::string(frame_data, static_cast<size_t>(pos));
-		RpcFrame frame(protocol, std::move(meta), std::move(data));
-		return frame;
-	}
-	case Rpc::ProtocolType::Cpon: {
-		CponReader rd(in);
-		RpcValue::MetaData meta;
-		rd.read(meta);
-		if(meta.isEmpty())
-			throw ParseException(CCPCP_RC_MALFORMED_INPUT, "Metadata missing", -1, {});
-		auto pos = in.tellg();
-		if(pos < 0)
-			throw ParseException(CCPCP_RC_MALFORMED_INPUT, "Metadata missing", -1, {});
-		auto data = std::string(frame_data, static_cast<size_t>(pos));
-		RpcFrame frame(protocol, std::move(meta), std::move(data));
-		return frame;
-	}
+	case Rpc::ProtocolType::ChainPack:
+		rd = std::make_unique<ChainPackReader>(in);
+		break;
+	case Rpc::ProtocolType::Cpon:
+		rd = std::make_unique<CponReader>(in);
+		break;
 	default:
 		throw std::runtime_error("Invalid protocol type");
 	}
-	return {};
+	RpcValue::MetaData meta;
+	rd->read(meta);
+	if(meta.isEmpty())
+		throw ParseException(CCPCP_RC_MALFORMED_INPUT, "Metadata missing", -1, {});
+	auto pos = rd->readCount();
+	if(pos < 0)
+		throw ParseException(CCPCP_RC_MALFORMED_INPUT, "Metadata missing", -1, {});
+	auto data = std::string(frame_data, static_cast<size_t>(pos));
+	RpcFrame frame(protocol, std::move(meta), std::move(data));
+	return frame;
 }
 
 //==================================================================