3 files changed, 183 insertions, 0 deletions

diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index fbebed715..eeceaa655 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -106,6 +106,8 @@ add_library(common STATIC
     common_funcs.h
     common_paths.h
     common_types.h
+    dynamic_library.cpp
+    dynamic_library.h
     file_util.cpp
     file_util.h
     hash.h
diff --git a/src/common/dynamic_library.cpp b/src/common/dynamic_library.cpp
new file mode 100644
index 000000000..7ab54e9e4
--- /dev/null
+++ b/src/common/dynamic_library.cpp
@@ -0,0 +1,106 @@
+// Copyright 2019 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include <cstring>
+#include <string>
+#include <utility>
+
+#include <fmt/format.h>
+
+#include "common/dynamic_library.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(DynamicLibrary&& rhs) noexcept
+    : handle{std::exchange(rhs.handle, nullptr)} {}
+
+DynamicLibrary& DynamicLibrary::operator=(DynamicLibrary&& rhs) noexcept {
+    Close();
+    handle = std::exchange(rhs.handle, nullptr);
+    return *this;
+}
+
+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 fmt::format("{}-{}-{}.dll", libname, major, minor);
+    else if (major >= 0)
+        return fmt::format("{}-{}.dll", libname, major);
+    else
+        return fmt::format("{}.dll", libname);
+#elif defined(__APPLE__)
+    const char* prefix = std::strncmp(libname, "lib", 3) ? "lib" : "";
+    if (major >= 0 && minor >= 0)
+        return fmt::format("{}{}.{}.{}.dylib", prefix, libname, major, minor);
+    else if (major >= 0)
+        return fmt::format("{}{}.{}.dylib", prefix, libname, major);
+    else
+        return fmt::format("{}{}.dylib", prefix, libname);
+#else
+    const char* prefix = std::strncmp(libname, "lib", 3) ? "lib" : "";
+    if (major >= 0 && minor >= 0)
+        return fmt::format("{}{}.so.{}.{}", prefix, libname, major, minor);
+    else if (major >= 0)
+        return fmt::format("{}{}.so.{}", prefix, libname, major);
+    else
+        return fmt::format("{}{}.so", prefix, libname);
+#endif
+}
+
+bool DynamicLibrary::Open(const char* filename) {
+#ifdef _WIN32
+    handle = reinterpret_cast<void*>(LoadLibraryA(filename));
+#else
+    handle = dlopen(filename, RTLD_NOW);
+#endif
+    return handle != nullptr;
+}
+
+void DynamicLibrary::Close() {
+    if (!IsOpen())
+        return;
+
+#ifdef _WIN32
+    FreeLibrary(reinterpret_cast<HMODULE>(handle));
+#else
+    dlclose(handle);
+#endif
+    handle = nullptr;
+}
+
+void* DynamicLibrary::GetSymbolAddress(const char* name) const {
+#ifdef _WIN32
+    return reinterpret_cast<void*>(GetProcAddress(reinterpret_cast<HMODULE>(handle), name));
+#else
+    return reinterpret_cast<void*>(dlsym(handle, name));
+#endif
+}
+
+} // namespace Common
diff --git a/src/common/dynamic_library.h b/src/common/dynamic_library.h
new file mode 100644
index 000000000..2a06372fd
--- /dev/null
+++ b/src/common/dynamic_library.h
@@ -0,0 +1,75 @@
+// Copyright 2019 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#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.
+    explicit DynamicLibrary();
+
+    /// Automatically loads the specified library. Call IsOpen() to check validity before use.
+    explicit DynamicLibrary(const char* filename);
+
+    /// Moves the library.
+    DynamicLibrary(DynamicLibrary&&) noexcept;
+    DynamicLibrary& operator=(DynamicLibrary&&) noexcept;
+
+    /// Delete copies, we can't copy a dynamic library.
+    DynamicLibrary(const DynamicLibrary&) = delete;
+    DynamicLibrary& operator=(const DynamicLibrary&) = delete;
+
+    /// 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 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* handle = nullptr;
+};
+
+} // namespace Common