Common: Add DynamicLibrary helper class

Source/Core/Common/CMakeLists.txt

@@ -11,6 +11,7 @@ add_library(common
   Crypto/ec.cpp
   Debug/MemoryPatches.cpp
   Debug/Watches.cpp
+  DynamicLibrary.cpp
   ENetUtil.cpp
   File.cpp
   FileSearch.cpp

Source/Core/Common/Common.vcxproj

@@ -63,6 +63,7 @@
     <ClInclude Include="DebugInterface.h" />
     <ClInclude Include="Debug\MemoryPatches.h" />
     <ClInclude Include="Debug\Watches.h" />
+    <ClInclude Include="DynamicLibrary.h" />
     <ClInclude Include="ENetUtil.h" />
     <ClInclude Include="Event.h" />
     <ClInclude Include="File.h" />
@@ -184,6 +185,7 @@
     <ClCompile Include="Config\Layer.cpp" />
     <ClCompile Include="Debug\MemoryPatches.cpp" />
     <ClCompile Include="Debug\Watches.cpp" />
+    <ClCompile Include="DynamicLibrary.cpp" />
     <ClCompile Include="ENetUtil.cpp" />
     <ClCompile Include="File.cpp" />
     <ClCompile Include="FileSearch.cpp" />
@@ -258,4 +260,4 @@
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
-</Project>
+</Project>

Source/Core/Common/Common.vcxproj.filters

@@ -276,6 +276,8 @@
     <ClInclude Include="GL\GLContext.h">
       <Filter>GL\GLInterface</Filter>
     </ClInclude>
+    <ClInclude Include="VariantUtil.h" />
+    <ClInclude Include="DynamicLibrary.h" />
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="CDUtils.cpp" />
@@ -357,6 +359,7 @@
     <ClCompile Include="GL\GLContext.cpp">
       <Filter>GL\GLInterface</Filter>
     </ClCompile>
+    <ClCompile Include="DynamicLibrary.cpp" />
   </ItemGroup>
   <ItemGroup>
     <Text Include="CMakeLists.txt" />
@@ -364,4 +367,4 @@
   <ItemGroup>
     <Natvis Include="BitField.natvis" />
   </ItemGroup>
-</Project>
+</Project>

Source/Core/Common/DynamicLibrary.cpp

@@ -0,0 +1,100 @@
+// Copyright 2019 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include "Common/DynamicLibrary.h"
+#include <cstring>
+#include "Common/Assert.h"
+#include "Common/StringUtil.h"
+
+#ifdef _WIN32
+#include <Windows.h>
+#else
+#include <dlfcn.h>
+#endif
+
+namespace Common
+{
+DynamicLibrary::DynamicLibrary() = default;
+
+DynamicLibrary::DynamicLibrary(const char* filename)
+{
+  Open(filename);
+}
+
+DynamicLibrary::~DynamicLibrary()
+{
+  Close();
+}
+
+std::string DynamicLibrary::GetUnprefixedFilename(const char* filename)
+{
+#if defined(_WIN32)
+  return std::string(filename) + ".dll";
+#elif defined(__APPLE__)
+  return std::string(filename) + ".dylib";
+#else
+  return std::string(filename) + ".so";
+#endif
+}
+
+std::string DynamicLibrary::GetVersionedFilename(const char* libname, int major, int minor)
+{
+#if defined(_WIN32)
+  if (major >= 0 && minor >= 0)
+    return StringFromFormat("%s-%d-%d.dll", libname, major, minor);
+  else if (major >= 0)
+    return StringFromFormat("%s-%d.dll", libname, major);
+  else
+    return StringFromFormat("%s.dll", libname);
+#elif defined(__APPLE__)
+  const char* prefix = std::strncmp(libname, "lib", 3) ? "lib" : "";
+  if (major >= 0 && minor >= 0)
+    return StringFromFormat("%s%s.%d.%d.dylib", prefix, libname, major, minor);
+  else if (major >= 0)
+    return StringFromFormat("%s%s.%d.dylib", prefix, libname, major);
+  else
+    return StringFromFormat("%s%s.dylib", prefix, libname);
+#else
+  const char* prefix = std::strncmp(libname, "lib", 3) ? "lib" : "";
+  if (major >= 0 && minor >= 0)
+    return StringFromFormat("%s%s.so.%d.%d", prefix, libname, major, minor);
+  else if (major >= 0)
+    return StringFromFormat("%s%s.so.%d", prefix, libname, major);
+  else
+    return StringFromFormat("%s%s.so", prefix, libname);
+#endif
+}
+
+bool DynamicLibrary::Open(const char* filename)
+{
+#ifdef _WIN32
+  m_handle = reinterpret_cast<void*>(LoadLibraryA(filename));
+#else
+  m_handle = dlopen(filename, RTLD_NOW);
+#endif
+  return m_handle != nullptr;
+}
+
+void DynamicLibrary::Close()
+{
+  if (!IsOpen())
+    return;
+
+#ifdef _WIN32
+  FreeLibrary(reinterpret_cast<HMODULE>(m_handle));
+#else
+  dlclose(m_handle);
+#endif
+  m_handle = nullptr;
+}
+
+void* DynamicLibrary::GetSymbolAddress(const char* name) const
+{
+#ifdef _WIN32
+  return reinterpret_cast<void*>(GetProcAddress(reinterpret_cast<HMODULE>(m_handle), name));
+#else
+  return reinterpret_cast<void*>(dlsym(m_handle, name));
+#endif
+}
+}  // namespace Common

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