Common: Add DynamicLibrary

src/common/dynamic_library.h

@@ -0,0 +1,73 @@
+// SPDX-FileCopyrightText: 2019-2024 Connor McLaughlin <stenzek@gmail.com>
+// SPDX-License-Identifier: (GPL-3.0 OR CC-BY-NC-ND-4.0)
+
+#pragma once
+
+#include <string>
+
+class Error;
+
+/**
+ * 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);
+
+  /// Move constructor, transfers ownership.
+  DynamicLibrary(DynamicLibrary&& move);
+
+  /// 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, Error* error);
+
+  /// Unloads the library, any function pointers from this library are no longer valid.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;
+  }
+
+  /// Move assignment, transfer ownership.
+  DynamicLibrary& operator=(DynamicLibrary&& move);
+
+private:
+  DynamicLibrary(const DynamicLibrary&) = delete;
+  DynamicLibrary& operator=(const DynamicLibrary&) = delete;
+
+  /// Platform-dependent data type representing a dynamic library handle.
+  void* m_handle = nullptr;
+};