util/library: Cross-platform handler for library loading

Adds a utility class and functions to load libraries and symbols from libraries somewhat safely. Libraries are immediately unloaded when the last reference to them is lost, so the shared_ptr should be stored if the library is actually needed.

CMakeLists.txt

@@ -506,6 +506,8 @@ list(APPEND PROJECT_PRIVATE_SOURCE
 	"source/util/utility.hpp"
 	"source/util/utility.cpp"
 	"source/util/util-event.hpp"
+	"source/util/util-library.cpp"
+	"source/util/util-library.hpp"
 	"source/util/util-profiler.cpp"
 	"source/util/util-profiler.hpp"
 	"source/util/util-threadpool.cpp"

source/common.hpp

@@ -47,6 +47,7 @@
 #include "config.hpp"
 #include "strings.hpp"
 #include "version.hpp"
+#include "util/util-library.hpp"
 #include "util/util-math.hpp"
 #include "util/util-profiler.hpp"
 #include "util/util-threadpool.hpp"

source/util/util-library.cpp

@@ -0,0 +1,107 @@
+// Copyright (c) 2020 Michael Fabian Dirks <info@xaymar.com>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#include "util-library.hpp"
+#include <unordered_map>
+
+#if defined(_WIN32) || defined(_WIN64) || defined(__CYGWIN__) // Windows
+#define ST_WINDOWS
+#else
+#define ST_UNIX
+#endif
+
+#if defined(ST_WINDOWS)
+#include <Windows.h>
+#elif defined(ST_UNIX)
+#include <dlfcn.h>
+#endif
+
+util::library::library(std::filesystem::path file) : _library(nullptr)
+{
+#if defined(ST_WINDOWS)
+	SetLastError(ERROR_SUCCESS);
+	_library = reinterpret_cast<void*>(LoadLibraryW(file.wstring().c_str()));
+	if (!_library) {
+		DWORD error = GetLastError();
+		if (error != ERROR_PROC_NOT_FOUND) {
+			PSTR        message = NULL;
+			std::string ex      = "Failed to load library.";
+			FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_ALLOCATE_BUFFER,
+						   NULL, error, MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US), (LPSTR)&message, 0, NULL);
+			if (message) {
+				ex = message;
+				LocalFree(message);
+				throw std::runtime_error(ex);
+			}
+		}
+		throw std::runtime_error("Failed to load library.");
+	}
+#elif defined(ST_UNIX)
+	_library = dlopen(file.string().c_str(), RTLD_LAZY);
+	if (!_library) {
+		if (char* error = dlerror(); error)
+			throw std::runtime_error(error);
+		else
+			throw std::runtime_error("Failed to load library.");
+	}
+#endif
+}
+
+util::library::~library()
+{
+#if defined(ST_WINDOWS)
+	FreeLibrary(reinterpret_cast<HMODULE>(_library));
+#elif defined(ST_UNIX)
+	dlclose(_library);
+#endif
+}
+
+void* util::library::load_symbol(std::string name)
+{
+#if defined(ST_WINDOWS)
+	return reinterpret_cast<void*>(GetProcAddress(reinterpret_cast<HMODULE>(_library), name.c_str()));
+#elif defined(ST_UNIX)
+	return reinterpret_cast<void*>(dlsym(_library, name.c_str()));
+#endif
+}
+
+static std::unordered_map<std::string, std::weak_ptr<::util::library>> libraries;
+
+std::shared_ptr<::util::library> util::library::load(std::filesystem::path file)
+{
+	std::string utf8_name = file.string();
+
+	auto kv = libraries.find(utf8_name);
+	if (kv != libraries.end()) {
+		if (auto ptr = kv->second.lock(); ptr)
+			return ptr;
+		libraries.erase(kv);
+	}
+
+	auto ptr = std::make_shared<::util::library>(file);
+	libraries.emplace(utf8_name, ptr);
+
+	return ptr;
+}
+
+std::shared_ptr<::util::library> util::library::load(std::string name)
+{
+	return load(std::filesystem::path(name));
+}

source/util/util-library.hpp

@@ -0,0 +1,40 @@
+// Copyright (c) 2020 Michael Fabian Dirks <info@xaymar.com>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#pragma once
+#include <filesystem>
+#include <memory>
+#include <string>
+
+namespace util {
+	class library {
+		void* _library;
+
+		public:
+		library(std::filesystem::path file);
+		~library();
+
+		void* load_symbol(std::string name);
+
+		static std::shared_ptr<::util::library> load(std::filesystem::path file);
+
+		static std::shared_ptr<::util::library> load(std::string name);
+	};
+} // namespace util