Common: Add DynamicLibrary helper class

Source/Core/Common/DynamicLibrary.h

@@ -0,0 +1,67 @@
+// Copyright 2019 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+#include <atomic>
+#include <string>
+
+namespace Common
+{
+/**
+ * Provides a platform-independent interface for loading a dynamic library and retrieving symbols.
+ * The interface maintains an internal reference count to allow one handle to be shared between
+ * multiple users.
+ */
+class DynamicLibrary final
+{
+public:
+  // Default constructor, does not load a library.
+  DynamicLibrary();
+
+  // Automatically loads the specified library. Call IsOpen() to check validity before use.
+  DynamicLibrary(const char* filename);
+
+  // Closes the library.
+  ~DynamicLibrary();
+
+  // Returns the specified library name with the platform-specific suffix added.
+  static std::string GetUnprefixedFilename(const char* filename);
+
+  // Returns the specified library name in platform-specific format.
+  // Major/minor versions will not be included if set to -1.
+  // If libname already contains the "lib" prefix, it will not be added again.
+  // Windows: LIBNAME-MAJOR-MINOR.dll
+  // Linux: libLIBNAME.so.MAJOR.MINOR
+  // Mac: libLIBNAME.MAJOR.MINOR.dylib
+  static std::string GetVersionedFilename(const char* libname, int major = -1, int minor = -1);
+
+  // Returns true if a module is loaded, otherwise false.
+  bool IsOpen() const { return m_handle != nullptr; }
+
+  // Loads (or replaces) the handle with the specified library file name.
+  // Returns true if the library was loaded and can be used.
+  bool Open(const char* filename);
+
+  // Unloads the library, any function pointers from this library are no longer valid.
+  void Close();
+
+  // Returns the address of the specified symbol (function or variable) as an untyped pointer.
+  // If the specified symbol does not exist in this library, nullptr is returned.
+  void* GetSymbolAddress(const char* name) const;
+
+  // Obtains the address of the specified symbol, automatically casting to the correct type.
+  // Returns true if the symbol was found and assigned, otherwise false.
+  template <typename T>
+  bool GetSymbol(const char* name, T* ptr) const
+  {
+    *ptr = reinterpret_cast<T>(GetSymbolAddress(name));
+    return *ptr != nullptr;
+  }
+
+private:
+  // Platform-dependent data type representing a dynamic library handle.
+  void* m_handle = nullptr;
+};
+
+}  // namespace Common