[WIP] Zipper to download artists/releases, ref #37

src/libs/utils/include/utils/Path.hpp

@@ -26,7 +26,7 @@
 
 #include <Wt/WDateTime.h>
 
-void computeCrc(const std::filesystem::path& p, std::vector<unsigned char>& checksum);
+std::uint32_t computeCrc32(const std::filesystem::path& p);
 
 // Make sure the given path is a directory
 // Create it if needed

src/libs/utils/include/utils/String.hpp

@@ -71,6 +71,7 @@ template<>
 std::optional<std::string>
 readAs(const std::string& str);
 
+[[nodiscard]]
 std::string
 replaceInString(const std::string& str, const std::string& from, const std::string& to);
 

src/libs/utils/include/utils/Zipper.hpp

@@ -0,0 +1,94 @@
+/*
+ * 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/>.
+ */
+
+#pragma once
+
+#include <map>
+#include <set>
+#include <filesystem>
+
+#include "Exception.hpp"
+
+namespace Zip
+{
+
+	class ZipperException : public LmsException
+	{
+		using LmsException::LmsException;
+	};
+
+	// Very simple on-the-fly zip creator
+	class Zipper
+	{
+		public:
+
+			enum class CompressionMethod
+			{
+				NoCompression,
+			};
+
+			Zipper(const std::map<std::string, std::filesystem::path>& files, CompressionMethod comp = CompressionMethod::NoCompression);
+
+			static constexpr std::size_t minOutputBufferSize = 64;
+			std::size_t writeSome(std::byte* buffer, std::size_t bufferSize);
+			bool isComplete() const;
+
+		private:
+			void setComplete();
+
+			std::size_t writeLocalFileHeader(std::byte* buffer, std::size_t bufferSize);
+			std::size_t writeLocalFileHeaderFileName(std::byte* buffer, std::size_t bufferSize);
+			std::size_t writeFileData(std::byte* buffer, std::size_t bufferSize);
+			std::size_t writeCentralDirectoryHeader(std::byte* buffer, std::size_t bufferSize);
+			std::size_t writeCentralDirectoryHeaderFileName(std::byte* buffer, std::size_t bufferSize);
+			std::size_t writeEndOfCentralDirectoryRecord(std::byte* buffer, std::size_t bufferSize);
+
+			struct FileContext
+			{
+				std::filesystem::path filePath;
+				std::size_t fileSize;
+				std::uint32_t fileCrc32;
+				std::size_t localFileHeaderOffset {};
+			};
+
+			using FileContainer = std::map<std::string, FileContext>;
+			FileContainer _files;
+
+			enum class WriteState
+			{
+				LocalFileHeader,
+				LocalFileHeaderFileName,
+				FileData,
+				CentralDirectoryHeader,
+				CentralDirectoryHeaderFileName,
+				EndOfCentralDirectoryRecord,
+				Complete,
+			};
+
+			CompressionMethod _compMethod {CompressionMethod::NoCompression};
+			WriteState _writeState {WriteState::LocalFileHeader};
+			FileContainer::iterator _currentFile;
+			std::size_t _currentOffset {};
+			std::size_t _currentZipOffset {};
+			std::size_t _centralDirectoryOffset {};
+			std::size_t _centralDirectorySize {};
+	};
+
+} // namespace Zip
+