5 files changed, 199 insertions, 15 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
diff --git a/src/common/file_util.cpp b/src/common/file_util.cpp
index 41167f57a..35eee0096 100644
--- a/src/common/file_util.cpp
+++ b/src/common/file_util.cpp
@@ -3,6 +3,7 @@
 // Refer to the license.txt file included.
 
 #include <array>
+#include <limits>
 #include <memory>
 #include <sstream>
 #include <unordered_map>
@@ -530,11 +531,11 @@ void CopyDir(const std::string& source_path, const std::string& dest_path) {
 std::optional<std::string> GetCurrentDir() {
 // Get the current working directory (getcwd uses malloc)
 #ifdef _WIN32
-    wchar_t* dir;
-    if (!(dir = _wgetcwd(nullptr, 0))) {
+    wchar_t* dir = _wgetcwd(nullptr, 0);
+    if (!dir) {
 #else
-    char* dir;
-    if (!(dir = getcwd(nullptr, 0))) {
+    char* dir = getcwd(nullptr, 0);
+    if (!dir) {
 #endif
         LOG_ERROR(Common_Filesystem, "GetCurrentDirectory failed: {}", GetLastErrorMsg());
         return {};
@@ -918,19 +919,22 @@ void IOFile::Swap(IOFile& other) noexcept {
 
 bool IOFile::Open(const std::string& filename, const char openmode[], int flags) {
     Close();
+    bool m_good;
 #ifdef _WIN32
     if (flags != 0) {
         m_file = _wfsopen(Common::UTF8ToUTF16W(filename).c_str(),
                           Common::UTF8ToUTF16W(openmode).c_str(), flags);
+        m_good = m_file != nullptr;
     } else {
-        _wfopen_s(&m_file, Common::UTF8ToUTF16W(filename).c_str(),
-                  Common::UTF8ToUTF16W(openmode).c_str());
+        m_good = _wfopen_s(&m_file, Common::UTF8ToUTF16W(filename).c_str(),
+                           Common::UTF8ToUTF16W(openmode).c_str()) == 0;
     }
 #else
-    m_file = fopen(filename.c_str(), openmode);
+    m_file = std::fopen(filename.c_str(), openmode);
+    m_good = m_file != nullptr;
 #endif
 
-    return IsOpen();
+    return m_good;
 }
 
 bool IOFile::Close() {
@@ -956,7 +960,7 @@ u64 IOFile::Tell() const {
     if (IsOpen())
         return ftello(m_file);
 
-    return -1;
+    return std::numeric_limits<u64>::max();
 }
 
 bool IOFile::Flush() {
diff --git a/src/common/thread.cpp b/src/common/thread.cpp
index fe7a420cc..0cd2d10bf 100644
--- a/src/common/thread.cpp
+++ b/src/common/thread.cpp
@@ -28,11 +28,8 @@ namespace Common {
 #ifdef _MSC_VER
 
 // Sets the debugger-visible name of the current thread.
-// Uses undocumented (actually, it is now documented) trick.
-// http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vsdebug/html/vxtsksettingthreadname.asp
-
-// This is implemented much nicer in upcoming msvc++, see:
-// http://msdn.microsoft.com/en-us/library/xcb2z8hs(VS.100).aspx
+// Uses trick documented in:
+// https://docs.microsoft.com/en-us/visualstudio/debugger/how-to-set-a-thread-name-in-native-code
 void SetCurrentThreadName(const char* name) {
     static const DWORD MS_VC_EXCEPTION = 0x406D1388;
 
@@ -47,7 +44,7 @@ void SetCurrentThreadName(const char* name) {
 
     info.dwType = 0x1000;
     info.szName = name;
-    info.dwThreadID = -1; // dwThreadID;
+    info.dwThreadID = std::numeric_limits<DWORD>::max();
     info.dwFlags = 0;
 
     __try {