Isolate Audio file resource request handler to ease reuse. ref #36

src/libs/utils/impl/FileResourceHandler.cpp

@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2020 Emeric Poupon
+ *
+ * This file is part of LMS.
+ *
+ * LMS is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * LMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "utils/FileResourceHandler.hpp"
+
+#include <fstream>
+
+#include "utils/Logger.hpp"
+
+namespace FileResourceHandler
+{
+
+static constexpr std::size_t _chunkSize {262144};
+
+static
+std::optional<ContinuationData>
+handleRequestPiecewise(const Wt::Http::Request& request,
+				Wt::Http::Response& response,
+				ContinuationData continuationData)
+{
+	::uint64_t startByte {continuationData.offset};
+	std::ifstream ifs {continuationData.path.string().c_str(), std::ios::in | std::ios::binary};
+
+	LMS_LOG(UTILS, DEBUG) << "startByte = " << startByte;
+
+	if (startByte == 0)
+	{
+		if (!ifs)
+		{
+			LMS_LOG(UTILS, ERROR) << "Cannot open file stream for '" << continuationData.path.string() << "'";
+			response.setStatus(404);
+			return std::nullopt;
+		}
+		else
+		{
+			response.setStatus(200);
+		}
+
+		ifs.seekg(0, std::ios::end);
+		const ::uint64_t fileSize {static_cast<::uint64_t>(ifs.tellg())};
+		ifs.seekg(0, std::ios::beg);
+
+		LMS_LOG(UTILS, DEBUG) << "fileSize = " << fileSize;
+
+		const Wt::Http::Request::ByteRangeSpecifier ranges {request.getRanges(fileSize)};
+		if (!ranges.isSatisfiable())
+		{
+			std::ostringstream contentRange;
+			contentRange << "bytes */" << fileSize;
+			response.setStatus(416); // Requested range not satisfiable
+			response.addHeader("Content-Range", contentRange.str());
+
+			LMS_LOG(UTILS, DEBUG) << "Range not satisfiable";
+			return std::nullopt;
+		}
+
+		if (ranges.size() == 1)
+		{
+			LMS_LOG(UTILS, DEBUG) << "Range requested = " << ranges[0].firstByte() << "/" << ranges[0].lastByte();
+
+			response.setStatus(206);
+			startByte = ranges[0].firstByte();
+			continuationData.beyondLastByte = ranges[0].lastByte() + 1;
+
+			std::ostringstream contentRange;
+			contentRange << "bytes " << startByte << "-"
+				<< continuationData.beyondLastByte - 1 << "/" << fileSize;
+
+			response.addHeader("Content-Range", contentRange.str());
+			response.setContentLength(continuationData.beyondLastByte - startByte);
+		}
+		else
+		{
+			LMS_LOG(UTILS, DEBUG) << "No range requested";
+
+			continuationData.beyondLastByte = fileSize;
+			response.setContentLength(continuationData.beyondLastByte);
+		}
+	}
+
+	ifs.seekg(static_cast<std::istream::pos_type>(startByte));
+
+	std::vector<char> buf;
+	buf.resize(_chunkSize);
+
+	::uint64_t restSize = continuationData.beyondLastByte - startByte;
+	::uint64_t pieceSize = buf.size() > restSize ? restSize : buf.size();
+
+	ifs.read(&buf[0], pieceSize);
+	const ::uint64_t actualPieceSize {static_cast<::uint64_t>(ifs.gcount())};
+	response.out().write(&buf[0], actualPieceSize);
+
+	LMS_LOG(UTILS, DEBUG) << "Written " << actualPieceSize << " bytes";
+
+	LMS_LOG(UTILS, DEBUG) << "Progress: " << actualPieceSize << "/" << restSize;
+	if (ifs.good() && actualPieceSize < restSize)
+	{
+		ContinuationData newContinuationData {continuationData};
+		newContinuationData.offset = startByte + actualPieceSize;
+
+		LMS_LOG(UTILS, DEBUG) << "Job not complete! Next chunk offset = " << newContinuationData.offset;
+
+		return newContinuationData;
+	}
+	else
+	{
+		LMS_LOG(UTILS, DEBUG) << "Job complete!";
+	}
+
+	return std::nullopt;
+}
+
+
+std::optional<ContinuationData>
+handleInitialRequest(const Wt::Http::Request& request,
+			Wt::Http::Response& response,
+			const std::filesystem::path& path)
+{
+	ContinuationData continuationData;
+	continuationData.path = path;
+	continuationData.offset = 0;
+	continuationData.beyondLastByte = 0;
+
+	LMS_LOG(UTILS, DEBUG) << "Initial request for file '" << path << "'";
+
+	return handleRequestPiecewise(request, response, continuationData);
+}
+
+std::optional<ContinuationData>
+handleContinuationRequest(const Wt::Http::Request& request,
+			Wt::Http::Response& response,
+			const ContinuationData& continuationData)
+{
+	LMS_LOG(UTILS, DEBUG) << "Continuation request for file '" << continuationData.path << "', offset = " << continuationData.offset;
+	return handleRequestPiecewise(request, response, continuationData);
+}
+
+} // ns FileResourceHandler
+
+
+

src/libs/utils/impl/Logger.cpp

@@ -37,6 +37,7 @@ const char* getModuleName(Module mod)
 		case Module::RECOMMENDATION:	return "RECOMMENDATION";
 		case Module::TRANSCODE:		return "TRANSCODE";
 		case Module::UI:		return "UI";
+		case Module::UTILS:		return "UTILS";
 	}
 	return "";
 }